Science.gov

Sample records for additional radial velocity

  1. Photoelectric Radial Velocities, Paper XIX Additional Spectroscopic Binaries among the Redman K Stars

    NASA Astrophysics Data System (ADS)

    Griffin, R. F.

    2012-06-01

    The `Redman K stars' project, described more particularly in the paper immediately following this one, involved the repeated measurement on a quasi-annual basis of the radial velocities of a group of 86 seventh-magnitude late-type stars over an interval of 45 years. Certain of the stars proved to vary in velocity and were then transferred to a different observing programme, in which they were measured more frequently with a view to determining their orbits. Orbits have already been published for 18 of the stars. Presented here (and summarized in Table 9) are the results on six more; all are single-lined. One of them (HD 191046, a star which has a literature coverage about ten times as rich as that of any of the others, probably on account of its high space velocity which includes a γ-velocity of nearly -100 km s - 1) has a good orbit with a period of about 8000 days (22 years). Five others (HD 3345, 15728, 20509, 188058 and 191084) have orbits that are perfectly secure in principle, but their periods range between 40 and perhaps 70 years, and (particularly in some cases) their radial velocities have not been observed well enough for long enough to establish either the periods or the orbits very accurately. One star, HD 9354, has exhibited a monotonic variation of velocity throughout the duration of the observing programme; it is possible to draw a Keplerian velocity curve that does justice to the measurements, but it cannot be expected to have much predictive power.

  2. Radial velocity confirmation of Kepler-91 b. Additional evidence of its planetary nature using the Calar Alto/CAFE instrument

    NASA Astrophysics Data System (ADS)

    Lillo-Box, J.; Barrado, D.; Henning, Th.; Mancini, L.; Ciceri, S.; Figueira, P.; Santos, N. C.; Aceituno, J.; Sánchez, S. F.

    2014-08-01

    The object transiting the star Kepler-91 was recently assessed as being of planetary nature. The confirmation was achieved by analysing the light-curve modulations observed in the Kepler data. However, quasi-simultaneous studies claimed a self-luminous nature for this object, thus rejecting it as a planet. In this work, we apply anindependent approach to confirm the planetary mass of Kepler-91b by using multi-epoch high-resolution spectroscopy obtained with the Calar Alto Fiber-fed Echelle spectrograph (CAFE). We obtain the physical and orbital parameters with the radial velocity technique. In particular, we derive a value of 1.09 ± 0.20 MJup for the mass of Kepler-91b, in excellent agreement with our previous estimate that was based on the orbital brightness modulation.

  3. PRECISION RADIAL VELOCITIES WITH CSHELL

    SciTech Connect

    Crockett, Christopher J.; Prato, L.; Mahmud, Naved I.; Johns-Krull, Christopher M.; Jaffe, Daniel T.; Beichman, Charles A. E-mail: lprato@lowell.edu E-mail: cmj@rice.edu

    2011-07-10

    Radial velocity (RV) identification of extrasolar planets has historically been dominated by optical surveys. Interest in expanding exoplanet searches to M dwarfs and young stars, however, has motivated a push to improve the precision of near-infrared RV techniques. We present our methodology for achieving 58 m s{sup -1} precision in the K band on the M0 dwarf GJ 281 using the CSHELL spectrograph at the 3 m NASA Infrared Telescope Facility. We also demonstrate our ability to recover the known 4 M{sub JUP} exoplanet Gl 86 b and discuss the implications for success in detecting planets around 1-3 Myr old T Tauri stars.

  4. RADIAL VELOCITY ECLIPSE MAPPING OF EXOPLANETS

    SciTech Connect

    Nikolov, Nikolay; Sainsbury-Martinez, Felix

    2015-07-20

    Planetary rotation rates and obliquities provide information regarding the history of planet formation, but have not yet been measured for evolved extrasolar planets. Here we investigate the theoretical and observational perspective of the Rossiter–McLaughlin effect during secondary eclipse (RMse) ingress and egress for transiting exoplanets. Near secondary eclipse, when the planet passes behind the parent star, the star sequentially obscures light from the approaching and receding parts of the rotating planetary surface. The temporal block of light emerging from the approaching (blueshifted) or receding (redshifted) parts of the planet causes a temporal distortion in the planet’s spectral line profiles resulting in an anomaly in the planet’s radial velocity curve. We demonstrate that the shape and the ratio of the ingress-to-egress radial velocity amplitudes depends on the planetary rotational rate, axial tilt, and impact factor (i.e., sky-projected planet spin–orbital alignment). In addition, line asymmetries originating from different layers in the atmosphere of the planet could provide information regarding zonal atmospheric winds and constraints on the hot spot shape for giant irradiated exoplanets. The effect is expected to be most-pronounced at near-infrared wavelengths, where the planet-to-star contrasts are large. We create synthetic near-infrared, high-dispersion spectroscopic data and demonstrate how the sky-projected spin axis orientation and equatorial velocity of the planet can be estimated. We conclude that the RMse effect could be a powerful method to measure exoplanet spins.

  5. Radial Velocity Fluctuations of RZ Psc

    NASA Astrophysics Data System (ADS)

    Potravnov, I. S.; Gorynya, N. A.; Grinin, V. P.; Minikulov, N. Kh.

    2014-12-01

    The behavior of the radial velocity of the UX Ori type star RZ Psc is studied. The existence of an inner cavity with a radius of about 0.7 a.u. in the circumstellar disk of this star allows to suggest the presence of a companion. A study of the radial velocity of RZ Psc based on our own measurements and published data yields no periodic component in its variability. The two most accurate measurements of V r , based on high resolution spectra obtained over a period of three months, show that the radial velocity is constant over this time interval to within 0.5 km/s. This imposes a limit of M p ≤10 M Jup on the mass of the hypothetical companion. Possible reasons for the observed strong fluctuations in the radial velocity of this star are discussed.

  6. The radial velocity search for extrasolar planets

    NASA Technical Reports Server (NTRS)

    Mcmillan, Robert S.

    1991-01-01

    Radial velocity measurements are being made to search for planets orbiting stars other than the Sun. The reflex acceleration induced on stars by planets can be sensed by measuring the small, slow changes in the line-of-site velocities of stars. To detect these planetary perturbations, the data series must be made on a uniform instrumental scale for as long as it takes a planet to orbit its star. A spectrometer of extreme stability and unprecedented sensitivity to changes in stellar radial velocities was operated.

  7. Radial velocity studies of cool stars.

    PubMed

    Jones, Hugh R A; Barnes, John; Tuomi, Mikko; Jenkins, James S; Anglada-Escude, Guillem

    2014-04-28

    Our current view of exoplanets is one derived primarily from solar-like stars with a strong focus on understanding our Solar System. Our knowledge about the properties of exoplanets around the dominant stellar population by number, the so-called low-mass stars or M dwarfs, is much more cursory. Based on radial velocity discoveries, we find that the semi-major axis distribution of M dwarf planets appears to be broadly similar to those around more massive stars and thus formation and migration processes might be similar to heavier stars. However, we find that the mass of M dwarf planets is relatively much lower than the expected mass dependency based on stellar mass and thus infer that planet formation efficiency around low-mass stars is relatively impaired. We consider techniques to overcome the practical issue of obtaining good quality radial velocity data for M dwarfs despite their faintness and sustained activity and emphasize (i) the wavelength sensitivity of radial velocity signals, (ii) the combination of radial velocity data from different experiments for robust detection of small amplitude signals, and (iii) the selection of targets and radial velocity interpretation of late-type M dwarfs should consider Hα behaviour.

  8. Radial velocity studies of cool stars.

    PubMed

    Jones, Hugh R A; Barnes, John; Tuomi, Mikko; Jenkins, James S; Anglada-Escude, Guillem

    2014-04-28

    Our current view of exoplanets is one derived primarily from solar-like stars with a strong focus on understanding our Solar System. Our knowledge about the properties of exoplanets around the dominant stellar population by number, the so-called low-mass stars or M dwarfs, is much more cursory. Based on radial velocity discoveries, we find that the semi-major axis distribution of M dwarf planets appears to be broadly similar to those around more massive stars and thus formation and migration processes might be similar to heavier stars. However, we find that the mass of M dwarf planets is relatively much lower than the expected mass dependency based on stellar mass and thus infer that planet formation efficiency around low-mass stars is relatively impaired. We consider techniques to overcome the practical issue of obtaining good quality radial velocity data for M dwarfs despite their faintness and sustained activity and emphasize (i) the wavelength sensitivity of radial velocity signals, (ii) the combination of radial velocity data from different experiments for robust detection of small amplitude signals, and (iii) the selection of targets and radial velocity interpretation of late-type M dwarfs should consider Hα behaviour. PMID:24664922

  9. Precise Near-Infrared Radial Velocities

    NASA Astrophysics Data System (ADS)

    Plavchan, Peter; Gao, P.; Bottom, M.; Davison, C.; Mills, S.; Ciardi, D. R.; Brinkworth, C.; Tanner, A. M.; Beichman, C. A.; Catanzarite, J.; Crawford, S.; Wallace, J.; Mennesson, B.; Johnson, J. A.; White, R. J.; Anglada-Escudé, G.; von Braun, K.; Walp, B.; Vasisht, G.; Kane, S. R.; Prato, L. A.; NIRRVs

    2014-01-01

    We present precise radial velocity time-series from a 2.3 micron pilot survey to detect exoplanets around red, low mass, and young stars. We use the CSHELL spectrograph with an isotopic methane absorption gas cell for common optical path relative wavelength calibration at the NASA InfraRed Telescope Facility. We present an overview of our Nelder-Mead simplex optimization pipeline for extracting radial velocities. We will also present first light data at 1.6 microns from a near-infrared fiber scrambler used in tandem with our gas cell and CSHELL at IRTF. The fiber scrambler makes use of non-circular core fibers to stabilize the illumination of the slit and echelle grating against changes in seeing, focus, guiding and other sources of systematic radial velocity noise, complementing the wavelength calibration of a gas cell.

  10. Radial velocities of Planetary Nebulae revisited

    NASA Astrophysics Data System (ADS)

    Vázquez, Roberto; Ayala, Sandra A.; Wendolyn Blanco Cárdenas, Mónica; Contreras, María E.; Gómez-Muñoz, Marco Antonio; Guillén, Pedro F.; Olguín, Lorenzo; Ramos-Larios, Gerardo; Sabin, Laurence; Zavala, Saúl A.

    2015-08-01

    We present a new determination of radial velocities of a sample of Galactic Planetary Nebulae (PNe) using a systematic method and the same instrumental setting: the long-slit high-dispersion Manchester Echelle Spectrograph (MES) on the 2.1-m telescope at the San Pedro Mártir Observatory (OAN-SPM; Mexico). This project was inspired by the work of Schneider et al. (1983, A&AS, 52, 399), which has been an important reference during the last decades. Radial velocities of gaseous nebulae can be obtained using the central wavelength of a Gaussian fit, even when there is an expansion velocity, as expected in PNe, but with not enough resolution to see a spectral line splitting. We have used the software SHAPE, a morpho-kinematic modeling and reconstruction tool for astrophysical objects (Steffen et al. 2011, IEEE Trans. Vis. Comput. Graphics, 17, 454), to prove that non-uniform density or brightness, on an expanding shell, can lead to mistaken conclusions about the radial velocity. To determine radial velocities, we only use the spectral data in which a spectral line-splitting is seen, avoiding thus the problem of the possible biased one-Gaussian fit. Cases when this method is not recommended are discussed.This project has been supported by grant PAPIIT-DGAPA-UNAM IN107914. MWB is in grateful receipt of a DGAPA-UNAM postdoctoral scholarship. MAG acknowledges CONACYT for his graduate scholarship.

  11. First results from the Radial Velocity Spectrometer

    NASA Astrophysics Data System (ADS)

    Seabroke, George; Cropper, Mark; Katz, David; Sartoretti, Paola; Panuzzo, Pasquale; Marchal, Olivier; Gueguen, Alain; Benson, Kevin; Dolding, Chris; Huckle, Howard; Smith, Mike; Baker, Steve

    2015-08-01

    Gaia's Radial Velocity Spectrometer (RVS) has been operating in routine phase for nearly one year since initial commissioning. RVS continues to work well but the higher than expected levels of stray light reduce the limiting magnitude. The end-of-mission radial velocity performance requirements are 15 km/s for G2V stars at V = 16.5 mag. 15 km/s accuracy is achieved at V ~ 15 mag, in agreement with simulations that predict a loss of 1.4 mag. RVS spectra are read out from the Gaia CCDs using windows, currently with a fixed Across Scan (AC) width of 10 pixels. Simulations suggest that adapting the AC window size and limiting magnitude to the observing conditions could recover ~0.1 mag of the faint-end performance loss. Consequently Gaia's onboard software will be upgraded in spring/summer 2015 (TBC) to include two new configurable functionalities: an adaptive RVS AC window size scheme and an adaptive RVS limiting magnitude scheme. The status of this new commissioning period will be presented, as well as the latest scientific performance of the on-ground processing of RVS spectra.

  12. Precise radial velocities in the near infrared

    NASA Astrophysics Data System (ADS)

    Redman, Stephen L.

    Since the first detection of a planet outside our Solar System byWolszczan & Frail (1992), over 500 exoplanets have been found to date2, none of which resemble the Earth. Most of these planets were discovered by measuring the radial velocity (hereafter, RV) of the host star, which wobbles under the gravitational influence of any existing planetary companions. However, this method has yet to achieve the sub-m/s precision necessary to detect an Earth-mass planet in the Habitable Zone (the region around a star that can support liquid water; hereafter, HZ) (Kasting et al. 1993) around a Solar-type star. Even though Kepler (Borucki et al. 2010) has announced several Earth-sized HZ candidates, these targets will be exceptionally difficult to confirm with current astrophysical spectrographs (Borucki et al. 2011). The fastest way to discover and confirm potentiallyhabitable Earth-mass planets is to observe stars with lower masses - in particular, late M dwarfs. While M dwarfs are readily abundant, comprising some 70% of the local stellar population, their low optical luminosity presents a formidable challenge to current optical RV instruments. By observing in the near-infrared (hereafter, NIR), where the flux from M dwarfs peaks, we can potentially reach low RV precisions with significantly less telescope time than would be required by a comparable optical instrument. However, NIR precision RV measurements are a relatively new idea and replete with challenges: IR arrays, unlike CCDs, are sensitive to the thermal background; modal noise is a bigger issue in the NIR than in the optical; and the NIR currently lacks the calibration sources like the very successful thorium-argon (hereafter, ThAr) hollow-cathode lamp and Iodine gas cell of the optical. The PSU Pathfinder (hereafter, Pathfinder) was designed to explore these technical issues with the intention of mitigating these problems for future NIR high-resolution spectrographs, such as the Habitable-Zone Planet Finder (HZPF

  13. Carbon star radial velocities and dark matter in the universe

    NASA Technical Reports Server (NTRS)

    Jura, M.

    1986-01-01

    Optical radial velocities of carbon stars in the Milky Way are compared to center-of-mass velocities derived from CO radio emission produced in their circumstellar envelopes. It seems that there is an intrinsic velocity dispersion in the optically measured radial velocities. If the carbon stars in the dwarf spheroidals behave in a fashion similar to those in the Milky Way, then the use of their optical radial velocities to infer the mass-to-light ratio of dwarf spheroidal galaxies and the nature of the dark matter in the universe is suspect. Measurement of the radial velocities of K giants may possibly avoid these uncertainties associated with atmospheric motions.

  14. The radial velocity search for extrasolar planets

    NASA Technical Reports Server (NTRS)

    Mcmillen, R. S.; Smith, P. H.

    1986-01-01

    Stars are observed with a ground-based instrument designed to measure small changes in the line-of-sight velocities. The purpose of the observations is to detect large planets by the oscillatory reflex motion they induce on the stars they are orbiting. The instrument is an optical spectrometer for which wavelengths are first calibrated by transmission through a tunable Fabry-Perot etalon interferometer. Changes in the line-of-sight velocities are revealed by changes in the Doppler shift of the absorption-line spectra of stars. The scrambling of incident light by an optical fiber and the stability of wavelength calibration by a tilt-tunable Fabry-Perot etalon provide immunity to systematic errors that historically have effected more conventional radial velocity spectrographs. A cross-dispersed echelle spectrograph spatially separates the orders of constructive interference transmitted through the etalon. Selecting several echelle diffraction orders in the vicinity of 4250 to 4750 A, which are imaged on a CCD, about 350 points on the profile of the stellar spectrum are sampled by successive orders of interferometric transmission through the etalon.

  15. Radial velocities of southern visual multiple stars

    SciTech Connect

    Tokovinin, Andrei; Pribulla, Theodor; Fischer, Debra E-mail: pribulla@ta3.sk

    2015-01-01

    High-resolution spectra of visual multiple stars were taken in 2008–2009 to detect or confirm spectroscopic subsystems and to determine their orbits. Radial velocities of 93 late-type stars belonging to visual multiple systems were measured by numerical cross-correlation. We provide the individual velocities, the width, and the amplitude of the Gaussians that approximate the correlations. The new information on the multiple systems resulting from these data is discussed. We discovered double-lined binaries in HD 41742B, HD 56593C, and HD 122613AB, confirmed several other known subsystems, and constrained the existence of subsystems in some visual binaries where both components turned out to have similar velocities. The orbits of double-lined subsystems with periods of 148 and 13 days are computed for HD 104471 Aa,Ab and HD 210349 Aa,Ab, respectively. We estimate individual magnitudes and masses of the components in these triple systems and update the outer orbit of HD 104471 AB.

  16. Bayesian planet searches in radial velocity data

    NASA Astrophysics Data System (ADS)

    Gregory, Phil

    2015-08-01

    Intrinsic stellar variability caused by magnetic activity and convection has become the main limiting factor for planet searches in both transit and radial velocity (RV) data. New spectrographs are under development like ESPRESSO and EXPRES that aim to improve RV precision by a factor of approximately 100 over the current best spectrographs, HARPS and HARPS-N. This will greatly exacerbate the challenge of distinguishing planetary signals from stellar activity induced RV signals. At the same time good progress has been made in simulating stellar activity signals. At the Porto 2014 meeting, “Towards Other Earths II,” Xavier Dumusque challenged the community to a large scale blind test using the simulated RV data to understand the limitations of present solutions to deal with stellar signals and to select the best approach. My talk will focus on some of the statistical lesson learned from this challenge with an emphasis on Bayesian methodology.

  17. Precision Radial Velocities in the Infrared

    NASA Astrophysics Data System (ADS)

    Jones, Hugh

    2007-08-01

    The Precision Radial Velocity Spectrometer (PRVS) is designed to provide high throughput Doppler reflex measurements. PRVS is designed to always be available and provide 1.0 to 1.8 micron high-resolution spectroscopy with very high stability over several years. We have constructed models simulating likely candidates and demonstrated the ability to recover exoplanetary RV signals in the infrared. We have conducted limited experiments with a brass-board instrument to explore real-world issues yielding precisions of better than 10 m/s. We are thus confident that PRVS can provide for the detection of terrestrial-mass extra-solar planets in the habitable zones of low-mass stars. PRVS is scheduled to be the next ASPEN-process instrument for the Gemini telescopes and if funded in 2007 first light is expected by 2011.

  18. Spectrographs for the Measurement of Radial Velocities

    NASA Astrophysics Data System (ADS)

    Baranne, A.

    A radial-velocity measurement derives from a shift in position of spectral features at the focus of a spectrographic instrument. We do not often think about how small these shifts are. It is not generally appreciated that the accuracy to which this shift must be measured is a tiny fraction of a pixel. Or, if we prefer to calculate in microns a surprising minuteness. What precautions should we be taking for the measurement of such small shifts? It is true that, thanks to computers, modern reduction methods allows us to correct for a wide variety of pertubations, provided that these are foreseen and understood; but such reduction procedures will give the best results if such pertubations are kept very small. We must therefore analyse these pertubations and think about how we can control them. The correlation method initiated in its modern form by Roger Griffin, and which we developed further with an optical mask in CORAVEL twenty-five years ago and more recently with a numerical mask in ELODIE, has demonstrated its power. In terms of these methods, the problem of high precision is to improve the correlation peak. Can this be done? Does the correlation method allow us to distinguish the overall radial velocity of the object from possible distortions of the lines? This is certainly a major problem which must be solved. The luminous efficiency of high-precision spectrographs is low. If the use of an optical fibre with scrambling for feeding the spectrograph seems inevitable to us today, it seems to me that the transmission of this system can be considerably improved by a better choice of the F-ratio of the image beam of the telescope which is to be matched with that of the spectrograph. This problem, common to all spectrographs, could be resolved with a specialised focal-plane instrument, giving a much greater than usual F-ratio, resulting in a simplification of the spectrograph optics, and hence an improvement in transmission and a serious decrease in size (which is

  19. Analysis of radial velocities in the Antlia cluster

    NASA Astrophysics Data System (ADS)

    Faifer, F. R.; Smith Castelli, A. V.; Calderón, J. P.; Caso, J. P.; Bassino, L. P.; Cellone, S. A.; Richtler, T.

    We present preliminary results of a radial velocity survey in the central re- gion of the Antlia cluster. These velocities have been measured on spec- tra obtained, in the 2008A and 2009A semesters, with GMOS (GEMINI South). In this way, several dwarf galaxies that had no previous radial ve- locities, have been confirmed as cluster members. Our work is based on the Ferguson & Sandage (1990) catalogue, in which originally only 6% of the catalogued galaxies (375) had radial velocities. Thanks to the newly determined radial velocities we are able to begin to disentangle the cluster internal structure. FULL TEXT IN SPANISH

  20. High precision radial velocities with GIANO spectra

    NASA Astrophysics Data System (ADS)

    Carleo, I.; Sanna, N.; Gratton, R.; Benatti, S.; Bonavita, M.; Oliva, E.; Origlia, L.; Desidera, S.; Claudi, R.; Sissa, E.

    2016-06-01

    Radial velocities (RV) measured from near-infrared (NIR) spectra are a potentially excellent tool to search for extrasolar planets around cool or active stars. High resolution infrared (IR) spectrographs now available are reaching the high precision of visible instruments, with a constant improvement over time. GIANO is an infrared echelle spectrograph at the Telescopio Nazionale Galileo (TNG) and it is a powerful tool to provide high resolution spectra for accurate RV measurements of exoplanets and for chemical and dynamical studies of stellar or extragalactic objects. No other high spectral resolution IR instrument has GIANO's capability to cover the entire NIR wavelength range (0.95-2.45 μm) in a single exposure. In this paper we describe the ensemble of procedures that we have developed to measure high precision RVs on GIANO spectra acquired during the Science Verification (SV) run, using the telluric lines as wavelength reference. We used the Cross Correlation Function (CCF) method to determine the velocity for both the star and the telluric lines. For this purpose, we constructed two suitable digital masks that include about 2000 stellar lines, and a similar number of telluric lines. The method is applied to various targets with different spectral type, from K2V to M8 stars. We reached different precisions mainly depending on the H-magnitudes: for H ˜ 5 we obtain an rms scatter of ˜ 10 m s-1, while for H ˜ 9 the standard deviation increases to ˜ 50 ÷ 80 m s-1. The corresponding theoretical error expectations are ˜ 4 m s-1 and 30 m s-1, respectively. Finally we provide the RVs measured with our procedure for the targets observed during GIANO Science Verification.

  1. RADIAL VELOCITY VARIABILITY OF FIELD BROWN DWARFS

    SciTech Connect

    Prato, L.; Mace, G. N.; Rice, E. L.; McLean, I. S.; Kirkpatrick, J. Davy; Burgasser, A. J.; Kim, Sungsoo S.

    2015-07-20

    We present paper six of the NIRSPEC Brown Dwarf Spectroscopic Survey, an analysis of multi-epoch, high-resolution (R ∼ 20,000) spectra of 25 field dwarf systems (3 late-type M dwarfs, 16 L dwarfs, and 6 T dwarfs) taken with the NIRSPEC infrared spectrograph at the W. M. Keck Observatory. With a radial velocity (RV) precision of ∼2 km s{sup −1}, we are sensitive to brown dwarf companions in orbits with periods of a few years or less given a mass ratio of 0.5 or greater. We do not detect any spectroscopic binary brown dwarfs in the sample. Given our target properties, and the frequency and cadence of observations, we use a Monte Carlo simulation to determine the detection probability of our sample. Even with a null detection result, our 1σ upper limit for very low mass binary frequency is 18%. Our targets included seven known, wide brown dwarf binary systems. No significant RV variability was measured in our multi-epoch observations of these systems, even for those pairs for which our data spanned a significant fraction of the orbital period. Specialized techniques are required to reach the high precisions sensitive to motion in orbits of very low-mass systems. For eight objects, including six T dwarfs, we present the first published high-resolution spectra, many with high signal to noise, that will provide valuable comparison data for models of brown dwarf atmospheres.

  2. Radial Velocity Monitoring of Kepler Heartbeat Stars

    NASA Astrophysics Data System (ADS)

    Shporer, Avi; Fuller, Jim; Isaacson, Howard; Hambleton, Kelly; Thompson, Susan E.; Prša, Andrej; Kurtz, Donald W.; Howard, Andrew W.; O'Leary, Ryan M.

    2016-09-01

    Heartbeat stars (HB stars) are a class of eccentric binary stars with close periastron passages. The characteristic photometric HB signal evident in their light curves is produced by a combination of tidal distortion, heating, and Doppler boosting near orbital periastron. Many HB stars continue to oscillate after periastron and along the entire orbit, indicative of the tidal excitation of oscillation modes within one or both stars. These systems are among the most eccentric binaries known, and they constitute astrophysical laboratories for the study of tidal effects. We have undertaken a radial velocity (RV) monitoring campaign of Kepler HB stars in order to measure their orbits. We present our first results here, including a sample of 22 Kepler HB systems, where for 19 of them we obtained the Keplerian orbit and for 3 other systems we did not detect a statistically significant RV variability. Results presented here are based on 218 spectra obtained with the Keck/HIRES spectrograph during the 2015 Kepler observing season, and they have allowed us to obtain the largest sample of HB stars with orbits measured using a single instrument, which roughly doubles the number of HB stars with an RV measured orbit. The 19 systems measured here have orbital periods from 7 to 90 days and eccentricities from 0.2 to 0.9. We show that HB stars draw the upper envelope of the eccentricity-period distribution. Therefore, HB stars likely represent a population of stars currently undergoing high eccentricity migration via tidal orbital circularization, and they will allow for new tests of high eccentricity migration theories. The data presented herein were obtained at the W.M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W.M. Keck Foundation.

  3. TRUE MASSES OF RADIAL-VELOCITY EXOPLANETS

    SciTech Connect

    Brown, Robert A.

    2015-06-01

    We study the task of estimating the true masses of known radial-velocity (RV) exoplanets by means of direct astrometry on coronagraphic images to measure the apparent separation between exoplanet and host star. Initially, we assume perfect knowledge of the RV orbital parameters and that all errors are due to photon statistics. We construct design reference missions for four missions currently under study at NASA: EXO-S and WFIRST-S, with external star shades for starlight suppression, EXO-C and WFIRST-C, with internal coronagraphs. These DRMs reveal extreme scheduling constraints due to the combination of solar and anti-solar pointing restrictions, photometric and obscurational completeness, image blurring due to orbital motion, and the “nodal effect,” which is the independence of apparent separation and inclination when the planet crosses the plane of the sky through the host star. Next, we address the issue of nonzero uncertainties in RV orbital parameters by investigating their impact on the observations of 21 single-planet systems. Except for two—GJ 676 A b and 16 Cyg B b, which are observable only by the star-shade missions—we find that current uncertainties in orbital parameters generally prevent accurate, unbiased estimation of true planetary mass. For the coronagraphs, WFIRST-C and EXO-C, the most likely number of good estimators of true mass is currently zero. For the star shades, EXO-S and WFIRST-S, the most likely numbers of good estimators are three and four, respectively, including GJ 676 A b and 16 Cyg B b. We expect that uncertain orbital elements currently undermine all potential programs of direct imaging and spectroscopy of RV exoplanets.

  4. Radial velocity fitting challenge. I. Simulating the data set including realistic stellar radial-velocity signals

    NASA Astrophysics Data System (ADS)

    Dumusque, X.

    2016-08-01

    Context. Stellar signals are the main limitation for precise radial-velocity (RV) measurements. These signals arise from the photosphere of the stars. The m s-1 perturbation created by these signals prevents the detection and mass characterization of small-mass planetary candidates such as Earth-twins. Several methods have been proposed to mitigate stellar signals in RV measurements. However, without precisely knowing the stellar and planetary signals in real observations, it is extremely difficult to test the efficiency of these methods. Aims: The goal of the RV fitting challenge is to generate simulated RV data including stellar and planetary signals and to perform a blind test within the community to test the efficiency of the different methods proposed to recover planetary signals despite stellar signals. Methods: In this first paper, we describe the simulation used to model the measurements of the RV fitting challenge. Each simulated planetary system includes the signals from instrumental noise, stellar oscillations, granulation, supergranulation, stellar activity, and observed and simulated planetary systems. In addition to RV variations, this simulation also models the effects of instrumental noise and stellar signals on activity observables obtained by HARPS-type high-resolution spectrographs, that is, the calcium activity index log (R'HK) and the bisector span and full width at half maximum of the cross-correlation function. Results: We publish the 15 systems used for the RV fitting challenge including the details about the planetary systems that were injected into each of them. Based on observations collected at the La Silla Parana Observatory, ESO (Chile), with the HARPS spectrograph at the 3.6-m telescope.The simulated data sets are available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/593/A5 and at the wiki of the RV fitting challenge http://https://rv-challenge.wikispaces.com.

  5. The Carina Project. IV. Radial Velocity Distribution

    NASA Astrophysics Data System (ADS)

    Fabrizio, M.; Nonino, M.; Bono, G.; Ferraro, I.; François, P.; Iannicola, G.; Monelli, M.; Thévenin, F.; Stetson, P. B.; Walker, A. R.; Buonanno, R.; Caputo, F.; Corsi, C. E.; Dall'Ora, M.; Gilmozzi, R.; James, C. R.; Merle, T.; Pulone, L.; Romaniello, M.

    2011-04-01

    We present new and accurate radial velocity (RV) measurements of luminous stars of all ages (old horizontal branch, intermediate-age red clump, and young blue plume, as well as red giants of a range of ages: 20.6 <= V <= 22) in the Carina dwarf spheroidal galaxy, based on low-resolution spectra collected with the FORS2 multiobject slit spectrograph at the VLT. This data set was complemented by RV measurements based on medium- and high-resolution archive spectra of brighter (V lsim 20.6) Carina targets collected with the GIRAFFE multiobject fiber spectrograph at the VLT. The combined sample includes more than 21,340 individual spectra of ≈2000 stars covering the entire body of the galaxy. The mean (langRVrang = 220.4 ± 0.1 km s-1) and the dispersion (σ = 11.7 ± 0.1 km s-1) of the RV distribution of candidate Carina stars (~1210 objects, 180 <= RV <= 260 km s-1, 4σ) agree quite well with similar measurements available in the literature. To further improve the statistics, the accurate RV measurements recently provided by Walker et al. were also added to the current data set. We ended up with a sample of ~1370 RV measurements of candidate Carina stars that is ≈75% larger than any previous Carina RV sample. We found that the hypothesis that the Carina RV distribution is Gaussian can be discarded at 99% confidence level. The mean RV across the body of the galaxy varies from ~220 km s-1 at a distance of 7' (~200 pc) from the center to ~223 km s-1 at 13' (~400 pc, 6σ level) and flattens out to a constant value of ~221 km s-1 at larger distances (600 pc, 4σ level). Moreover, and even more importantly, we found that in the Carina regions where the mean RV is smaller, the dispersion is also smaller, and the RV distribution is more centrally peaked (i.e., the kurtosis attains larger values). The difference in mean RV is more than 4 km s-1 (9σ level) when moving from east to west and more than 3 km s-1 (~7σ level) when moving from north to south. The RV gradient

  6. Radar Wind Profiler Radial Velocity: A Comparison with Doppler Lidar.

    NASA Astrophysics Data System (ADS)

    Cohn, Stephen A.; Goodrich, R. Kent

    2002-12-01

    The accuracy of the radial wind velocity measured with a radar wind profiler will depend on turbulent variability and instrumental noise. Radial velocity estimates of a boundary layer wind profiler are compared with those estimated by a Doppler lidar over 2.3 h. The lidar resolution volume was much narrower than the profiler volume, but the samples were well matched in range and time. The wind profiler radial velocity was computed using two common algorithms [profiler online program (POP) and National Center for Atmospheric Research improved moments algorithm (NIMA)]. The squared correlation between radial velocities measured with the two instruments was R2 = 0.99, and the standard deviation of the difference was about r = 0.20-0.23 m s1 for radial velocities of greater than 1 m s1 and r = 0.16-0.35 m s1 for radial velocities of less than 1 m s1. Small radial velocities may be treated differently in radar wind profiler processing because of ground-clutter mitigation strategies. A standard deviation of r = 0.23 m s1 implies an error in horizontal winds from turbulence and noise of less than 1 m s1 for a single cycle through the profiler beam directions and of less than 0.11-0.27 m s1 for a 30-min average measurement, depending on the beam pointing sequence. The accuracy of a wind profiler horizontal wind measurement will also depend on assumptions of spatial and temporal inhomogeneity of the atmosphere, which are not considered in this comparison. The wind profiler radial velocities from the POP and NIMA are in good agreement. However, the analysis does show the need for improvements in wind profiler processing when radial velocity is close to zero.

  7. ANALYSIS OF RADIAL VELOCITY DATA BY A NOVEL ADAPTIVE APPROACH

    SciTech Connect

    Babu, P.; Stoica, P.; Li, J.; Chen, Z.; Ge, J.

    2010-02-15

    In this paper, we introduce an estimation technique for analyzing radial velocity data commonly encountered in extrasolar planet detection. We discuss the Keplerian model for radial velocity data measurements and introduce a technique named the iterative adaptive approach (IAA) to estimate the three-dimensional spectrum (power versus eccentricity, orbital period and periastron passage time) of the radial velocity data. We then discuss different ways to regularize the IAA algorithm in the presence of noise and measurement errors. We also discuss briefly the computational aspects of the method and introduce a computationally efficient version of IAA. Finally, we establish the significance of the spectral peaks by using a relaxation maximum likelihood algorithm and a generalized likelihood ratio test. Numerical experiments are carried out on both simulated and real life data sets to evaluate the performance of our method. The real life data sets discussed are radial velocity measurements of the stars HD 63454, HD 208487, and GJ 876.

  8. Yellow giants - A new class of radial velocity variable

    SciTech Connect

    Walker, G.A.H.; Yang, S.; Campbell, B.; Irwin, A.W.; Victoria Univ. )

    1989-08-01

    The five K giants and one K supergiant included in a precise (HF) radial velocity program all show significant long-term (about 1 yr), low-amplitude (30-300 m/s rms) radial velocity variations which make them unsuitable as precise radial velocity standars. Arcturus has been discussed in detail elsewhere, and the supergiant Epsilon Peg is probably a semiregular variable. The sampling in the five years of data is inadequate to say whether the giants are related to the Cepheid or Mira variables or form an independent class. The amplitudes of the long-term radial velocity variations of the giants and supergiant are correlated with the level of chromospheric activity shown by K line emission intensity and its fluctuation as seen in He I 10830-A. 19 refs.

  9. The Radial Velocity Method for the Detection of Exoplanets

    NASA Astrophysics Data System (ADS)

    Hatzes, Artie P.

    The radial velocity (RV) method has provided the foundation for the research field of exoplanets. It created the field by discovering the first exoplanets and then blazed a trail by detecting over 1000 exoplanets in orbit around other stars. The method also plays a vital role in transit searches by providing the planetary mass needed to calculate the bulk density of the exoplanet. The RV method requires a wide range of techniques: novel instrumentation for making precise RV measurements, clever techniques for extracting the periodic signals due to planets from the RV data, tools for assessing their statistical significance, and programs for calculating the Keplerian orbital parameters. Finally, RV measurements have become so precise that the measurement error is now dominated by the intrinsic stellar noise. New tools have to be developed to extract planetary signals from RV variability originating from the star. In these series of lectures I will cover (1) basic instrumentation for stellar radial velocity methods, (2) methods for achieving high radial velocity precision, (3) finding periodic signals in radial velocity data, (4) Keplerian orbits, (5) sources of errors for radial velocity measurements, and (6) dealing with the contribution of stellar noise to the radial velocity measurement.

  10. Precise radial velocities of giant stars. VIII. Testing for the presence of planets with CRIRES infrared radial velocities

    NASA Astrophysics Data System (ADS)

    Trifonov, Trifon; Reffert, Sabine; Zechmeister, Mathias; Reiners, Ansgar; Quirrenbach, Andreas

    2015-10-01

    Context. We have been monitoring 373 very bright (V ≤ 6 mag) G and K giants with high precision optical Doppler spectroscopy for more than a decade at Lick Observatory. Our goal was to discover planetary companions around those stars and to better understand planet formation and evolution around intermediate-mass stars. However, in principle, long-term, g-mode nonradial stellar pulsations or rotating stellar features, such as spots, could effectively mimic a planetary signal in the radial velocity data. Aims: Our goal is to compare optical and infrared radial velocities for those stars with periodic radial velocity patterns and to test for consistency of their fitted radial velocity semiamplitudes. Thereby, we distinguish processes intrinsic to the star from orbiting companions as reason for the radial velocity periodicity observed in the optical. Methods: Stellar spectra with high spectral resolution have been taken in the H-band with the CRIRES near-infrared spectrograph at ESO's VLT for 20 stars of our Lick survey. Radial velocities are derived using many deep and stable telluric CO2 lines for precise wavelength calibration. Results: We find that the optical and near-infrared radial velocities of the giant stars in our sample are consistent. We present detailed results for eight stars in our sample previously reported to have planets or brown dwarf companions. All eight stars passed the infrared test. Conclusions: We conclude that the planet hypothesis provides the best explanation for the periodic radial velocity patterns observed for these giant stars. Based on observations collected at the European Southern Observatory, Chile, under program IDs 088.D-0132, 089.D-0186, 090.D-0155 and 091.D-0365.Appendix A is available in electronic form at http://www.aanda.org

  11. Radial velocities of remote globular clusters - stalking the missing mass

    SciTech Connect

    Peterson, R.C.

    1985-10-01

    Measurements good to 25 km/s are presented of radial velocities of five remote galactic globular clusters, based on aperture-plate spectra of individual stars at 3.0 A resolution. Velocities with respect to the galactic rest-frame of two individual systems, Eridanus and Palomar 14, are large enough to suggest a total mass for the Galaxy of 1 trillion solar masses. A similar mass is inferred from the average of the galactocentric distance times velocity squared. 36 references.

  12. The radial velocity search for extrasolar planets

    NASA Technical Reports Server (NTRS)

    Mcmillen, Robert S.

    1988-01-01

    Researchers are measuring small changes in the line-of-sight velocities of stars to detect the oscillating reflex acceleration induced by large planets. The intention is to observe enough stars for a long enough time to be able to make a statement of the probability of planets in a certain range of masses even if no planetary perturbations are detected. To make these measurements of Doppler shift with the required sensitivity, a new instrument was specifically designed, built and tested for this campaign of ground-based planet detection. The instrument is an optical spectrometer for which wavelengths are first calibrated by transmission through a tunable Fabry-Perot etalon interferometer. The intrinsic stability of the etalon and an image-scrambling fiber optic light feed provide great sensitivity to line-of-sight accelerations and immunity to systematic errors.

  13. Errors in radial velocity variance from Doppler wind lidar

    NASA Astrophysics Data System (ADS)

    Wang, H.; Barthelmie, R. J.; Doubrawa, P.; Pryor, S. C.

    2016-08-01

    A high-fidelity lidar turbulence measurement technique relies on accurate estimates of radial velocity variance that are subject to both systematic and random errors determined by the autocorrelation function of radial velocity, the sampling rate, and the sampling duration. Using both statistically simulated and observed data, this paper quantifies the effect of the volumetric averaging in lidar radial velocity measurements on the autocorrelation function and the dependence of the systematic and random errors on the sampling duration. For current-generation scanning lidars and sampling durations of about 30 min and longer, during which the stationarity assumption is valid for atmospheric flows, the systematic error is negligible but the random error exceeds about 10 %.

  14. RADIAL VELOCITY STUDIES OF CLOSE BINARY STARS. XV

    SciTech Connect

    Pribulla, Theodor; Rucinski, Slavek M.; Blake, R. M.; Lu, Wenxian; Thomson, J. R.; DeBond, Heide; Karmo, Toomas; De Ridder, Archie; Ogloza, Waldemar; Stachowski, Greg; Siwak, Michal E-mail: rucinski@astro.utoronto.ca E-mail: karmo@astro.utoronto.ca E-mail: ogloza@ap.krakow.pl E-mail: siwak@oa.uj.edu.pl

    2009-03-15

    Radial velocity (RV) measurements and sine curve fits to the orbital RV variations are presented for the last eight close binary systems analyzed in the same way as in the previous papers of this series: QX And, DY Cet, MR Del, HI Dra, DD Mon, V868 Mon, ER Ori, and Y Sex. For another seven systems (TT Cet, AA Cet, CW Lyn, V563 Lyr, CW Sge, LV Vir, and MW Vir), phase coverage is insufficient to provide reliable orbits but RVs of individual components were measured. Observations of a few complicated systems observed throughout the David Dunlap Observatory (DDO) close binary program are also presented; among them is an especially interesting multiple system V857 Her which-in addition to the contact binary-very probably contains one or more subdwarf components of much earlier spectral type. All suspected binaries which were found to be most probably pulsating stars are briefly discussed in terms of mean RVs and projected rotation velocities (vsin i) as well as spectral-type estimates. In two of them, CU CVn and V752 Mon, the broadening functions show a clear presence of nonradial pulsations. The previously missing spectral types for Paper I are given here in addition to such estimates for most of the program stars of this paper.

  15. ESPRESSO: the radial velocity machine for the VLT

    NASA Astrophysics Data System (ADS)

    Mégevand, Denis; Zerbi, Filippo M.; Di Marcantonio, Paolo; Cabral, Alexandre; Riva, Marco; Abreu, Manuel; Pepe, Francesco; Cristiani, Stefano; Rebolo Lopez, Rafael; Santos, Nuno C.; Dekker, Hans; Aliverti, Matteo; Allende, Carlos; Amate, Manuel; Avila, Gerardo; Baldini, Veronica; Bandy, Timothy; Bristow, Paul; Broeg, Christopher; Cirami, Roberto; Coelho, João.; Conconi, Paolo; Coretti, Igor; Cupani, Guido; D'Odorico, Valentina; De Caprio, Vincenzo; Delabre, Bernard; Dorn, Reinhold; Figueira, Pedro; Fragoso, Ana; Galeotta, Samuele; Genolet, Ludovic; Gomes, Ricardo; González Hernández, Jonay; Hughes, Ian; Iwert, Olaf; Kerber, Florian; Landoni, Marco; Lizon, Jean-Louis; Lovis, Christophe; Maire, Charles; Mannetta, Marco; Martins, Carlos C. J. A. P.; Molaro, Paolo; Monteiro, Manuel A. S.; Moschetti, Manuele; Oliveira, Antonio; Zapatero Osorio, Maria Rosa; Poretti, Ennio; Rasilla, José L.; Santana Tschudi, Samuel; Santos, Pedro; Sosnowska, Danuta; Sousa, Sérgio; Tenegi, Fabio; Toso, Giorgio; Vanzella, Eros; Viel, Matteo

    2014-07-01

    ESPRESSO is the next generation ground based European exoplanets hunter. It will combine the efficiency of modern echelle spectrograph with extreme radial-velocity and spectroscopic precision. It will be installed at Paranal's VLT in order to achieve two magnitudes gain with respect to its predecessor HARPS, and the instrumental radial-velocity precision will be improved to reach 10 cm/s level. We have constituted a Consortium of astronomical research institutes to fund, design and build ESPRESSO on behalf of and in collaboration with ESO, the European Southern Observatory. The spectrograph will be installed at the Combined Coudé Laboratory (CCL) of the VLT, it will be linked to the four 8.2 meters Unit Telescopes through four optical "Coudé trains" and will be operated either with a single telescope or with up to four UTs, enabling an additional 1.5 magnitude gain. Thanks to its characteristics and ability of combining incoherently the light of 4 large telescopes, ESPRESSO will offer new possibilities in many fields of astronomy. Our main scientific objectives are, however, the search and characterization of rocky exoplanets in the habitable zone of quiet, near-by G to M-dwarfs, and the analysis of the variability of fundamental physical constants. The project is, for most of its workpackages, in the procurement or development phases, and the CCL infrastructure is presently under adaptation work. In this paper, we present the scientific objectives, the capabilities of ESPRESSO, the technical solutions for the system and its subsystems. The project aspects of this facility are also described, from the consortium and partnership structure to the planning phases and milestones.

  16. New systemic radial velocities of suspected RR Lyrae binary stars

    NASA Astrophysics Data System (ADS)

    Guggenberger, E.; Barnes, T. G.; Kolenberg, K.

    2016-05-01

    Among the tens of thousands of known RR Lyrae stars there are only a handful that show indications of possible binarity. The question why this is the case is still unsolved, and has recently sparked several studies dedicated to the search for additional RR Lyraes in binary systems. Such systems are particularly valuable because they might allow to constrain the stellar mass. Most of the recent studies, however, are based on photometry by finding a light time effect in the timings of maximum light. This approach is a very promising and successful one, but it has a major drawback: by itself, it cannot serve as a definite proof of binarity, because other phenomena such as the Blazhko effect or intrinsic period changes could lead to similar results. Spectroscopic radial velocity measurements, on the other hand, can serve as definite proof of binarity. We have therefore started a project to study spectroscopically RR Lyrae stars that are suspected to be binaries. We have obtained radial velocity (RV) curves with the 2.1m telescope at McDonald observatory. From these we derive systemic RVs which we will compare to previous measurements in order to find changes induced by orbital motions. We also construct templates of the RV curves that can facilitate future studies. We also observed the most promising RR Lyrae binary candidate, TU UMa, as no recent spectroscopic measurements were available. We present a densely covered pulsational RV curve, which will be used to test the predictions of the orbit models that are based on the O - C variations.

  17. A catalog of isolated galaxy pairs with accurate radial velocities

    NASA Astrophysics Data System (ADS)

    Chamaraux, P.; Nottale, L.

    2016-07-01

    The present paper is devoted to the construction of a catalog of isolated galaxy pairs from the Uppsala Galaxy Catalog (UGC), using accurate radial velocities. The UGC lists 12 921 galaxies to δ > -2°30' and is complete to an apparent diameter of 1'. The criteria used to define the isolated galaxy pairs are based on velocity, interdistance, reciprocity and isolation information. A peculiar investigation has allowed to gather very accurate radial velocities for pair members, from high quality HI and optical measurements (median uncertainty on velocity differences 10 kms-1). Our final catalog contains 1005 galaxy pairs with ρ > 2.5, of which 509 have ρ > 5 (50% of the pairs, i.e. 8%of the UGC galaxies) and 273 are highly isolated with ρ > 10 (27% of the pairs, i.e. 4% of the UGC galaxies). Some global properties of the pair catalog are given.

  18. Radial velocity information in solar-type spectra

    NASA Technical Reports Server (NTRS)

    Merline, W. J.

    1985-01-01

    A criterion is developed for determining the amount of radial velocity information theoretically available at the earth's surface from a star as a function of wavelength and spectral resolution. A description of the study is provided. The wavelength dependence is examined as well as the dependence on resolution, frequency information, and the problem of time-dependent astrophysical phenomena.

  19. RADIAL VELOCITIES OF GALACTIC HALO STARS IN VIRGO

    SciTech Connect

    Brink, Thomas G.; Mateo, Mario; Martinez-Delgado, David E-mail: mmateo@umich.ed

    2010-11-15

    We present multi-slit radial velocity measurements for 111 stars in the direction of the Virgo Stellar Stream (VSS). The stars were photometrically selected to be probable main-sequence stars in the Galactic halo. When compared with the radial velocity distribution expected for the halo of the Milky Way, as well as the distribution seen in a control field, we observe a significant excess of negative velocity stars in the field, which can likely be attributed to the presence of a stellar stream. This kinematic excess peaks at a Galactic standard of rest radial velocity of -75 km s{sup -1}. A rough distance estimate suggests that this feature extends from {approx}15 kpc out to, and possibly beyond, the {approx}30 kpc limit of the study. The mean velocity of these stars is incompatible with those of the VSS itself (V{sub gsr} {approx} 130 km s{sup -1}), which we weakly detect, but it is consistent with radial velocity measurements of nearby 2MASS M-giants and SDSS+SEGUE K/M-giants and blue horizontal branch stars that constitute the leading tidal tail of the Sagittarius dwarf spheroidal galaxy. Some oblate models for the shape of the Milky Way's dark matter halo predict that the leading arm of the Sagittarius Stream should pass through this volume, and have highly negative (V{sub gsr} {approx}< -200 km s{sup -1}) radial velocities, as it descends down from the northern Galactic hemisphere toward the Galactic plane. The kinematic feature observed in this study, if it is in fact Sagittarius debris, is not consistent with these predictions, and instead, like other leading stream radial velocity measurements, is consistent with a recently published triaxial halo model, or, if axisymmetry is imposed, favors a prolate shape for the Galactic halo potential. However, a rough distance estimate to the observed kinematic feature places it somewhat closer (D {approx} 15-30 kpc) than the Sagittarius models predict (D {approx} 35-45 kpc).

  20. A catalog of rotational and radial velocities for evolved stars

    NASA Astrophysics Data System (ADS)

    de Medeiros, J. R.; Mayor, M.

    1999-11-01

    Rotational and radial velocities have been measured for about 2000 evolved stars of luminosity classes IV, III, II and Ib covering the spectral region F, G and K. The survey was carried out with the CORAVEL spectrometer. The precision for the radial velocities is better than 0.30 km s-1, whereas for the rotational velocity measurements the uncertainties are typically 1.0 km s-1 for subgiants and giants and 2.0 km s-1 for class II giants and Ib supergiants. These data will add constraints to studies of the rotational behaviour of evolved stars as well as solid informations concerning the presence of external rotational brakes, tidal interactions in evolved binary systems and on the link between rotation, chemical abundance and stellar activity. In this paper we present the rotational velocity v sin i and the mean radial velocity for the stars of luminosity classes IV, III and II. Based on observations collected at the Haute--Provence Observatory, Saint--Michel, France and at the European Southern Observatory, La Silla, Chile. Table \\ref{tab5} also available in electronic form at CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/Abstract.html

  1. State of the Field: Extreme Precision Radial Velocities

    NASA Astrophysics Data System (ADS)

    Fischer, Debra A.; Anglada-Escude, Guillem; Arriagada, Pamela; Baluev, Roman V.; Bean, Jacob L.; Bouchy, Francois; Buchhave, Lars A.; Carroll, Thorsten; Chakraborty, Abhijit; Crepp, Justin R.; Dawson, Rebekah I.; Diddams, Scott A.; Dumusque, Xavier; Eastman, Jason D.; Endl, Michael; Figueira, Pedro; Ford, Eric B.; Foreman-Mackey, Daniel; Fournier, Paul; Fűrész, Gabor; Gaudi, B. Scott; Gregory, Philip C.; Grundahl, Frank; Hatzes, Artie P.; Hébrard, Guillaume; Herrero, Enrique; Hogg, David W.; Howard, Andrew W.; Johnson, John A.; Jorden, Paul; Jurgenson, Colby A.; Latham, David W.; Laughlin, Greg; Loredo, Thomas J.; Lovis, Christophe; Mahadevan, Suvrath; McCracken, Tyler M.; Pepe, Francesco; Perez, Mario; Phillips, David F.; Plavchan, Peter P.; Prato, Lisa; Quirrenbach, Andreas; Reiners, Ansgar; Robertson, Paul; Santos, Nuno C.; Sawyer, David; Segransan, Damien; Sozzetti, Alessandro; Steinmetz, Tilo; Szentgyorgyi, Andrew; Udry, Stéphane; Valenti, Jeff A.; Wang, Sharon X.; Wittenmyer, Robert A.; Wright, Jason T.

    2016-06-01

    The Second Workshop on Extreme Precision Radial Velocities defined circa 2015 the state of the art Doppler precision and identified the critical path challenges for reaching 10 cm s-1 measurement precision. The presentations and discussion of key issues for instrumentation and data analysis and the workshop recommendations for achieving this bold precision are summarized here. Beginning with the High Accuracy Radial Velocity Planet Searcher spectrograph, technological advances for precision radial velocity (RV) measurements have focused on building extremely stable instruments. To reach still higher precision, future spectrometers will need to improve upon the state of the art, producing even higher fidelity spectra. This should be possible with improved environmental control, greater stability in the illumination of the spectrometer optics, better detectors, more precise wavelength calibration, and broader bandwidth spectra. Key data analysis challenges for the precision RV community include distinguishing center of mass (COM) Keplerian motion from photospheric velocities (time correlated noise) and the proper treatment of telluric contamination. Success here is coupled to the instrument design, but also requires the implementation of robust statistical and modeling techniques. COM velocities produce Doppler shifts that affect every line identically, while photospheric velocities produce line profile asymmetries with wavelength and temporal dependencies that are different from Keplerian signals. Exoplanets are an important subfield of astronomy and there has been an impressive rate of discovery over the past two decades. However, higher precision RV measurements are required to serve as a discovery technique for potentially habitable worlds, to confirm and characterize detections from transit missions, and to provide mass measurements for other space-based missions. The future of exoplanet science has very different trajectories depending on the precision that can

  2. State of the Field: Extreme Precision Radial Velocities

    NASA Astrophysics Data System (ADS)

    Fischer, Debra A.; Anglada-Escude, Guillem; Arriagada, Pamela; Baluev, Roman V.; Bean, Jacob L.; Bouchy, Francois; Buchhave, Lars A.; Carroll, Thorsten; Chakraborty, Abhijit; Crepp, Justin R.; Dawson, Rebekah I.; Diddams, Scott A.; Dumusque, Xavier; Eastman, Jason D.; Endl, Michael; Figueira, Pedro; Ford, Eric B.; Foreman-Mackey, Daniel; Fournier, Paul; Fűrész, Gabor; Gaudi, B. Scott; Gregory, Philip C.; Grundahl, Frank; Hatzes, Artie P.; Hébrard, Guillaume; Herrero, Enrique; Hogg, David W.; Howard, Andrew W.; Johnson, John A.; Jorden, Paul; Jurgenson, Colby A.; Latham, David W.; Laughlin, Greg; Loredo, Thomas J.; Lovis, Christophe; Mahadevan, Suvrath; McCracken, Tyler M.; Pepe, Francesco; Perez, Mario; Phillips, David F.; Plavchan, Peter P.; Prato, Lisa; Quirrenbach, Andreas; Reiners, Ansgar; Robertson, Paul; Santos, Nuno C.; Sawyer, David; Segransan, Damien; Sozzetti, Alessandro; Steinmetz, Tilo; Szentgyorgyi, Andrew; Udry, Stéphane; Valenti, Jeff A.; Wang, Sharon X.; Wittenmyer, Robert A.; Wright, Jason T.

    2016-06-01

    The Second Workshop on Extreme Precision Radial Velocities defined circa 2015 the state of the art Doppler precision and identified the critical path challenges for reaching 10 cm s‑1 measurement precision. The presentations and discussion of key issues for instrumentation and data analysis and the workshop recommendations for achieving this bold precision are summarized here. Beginning with the High Accuracy Radial Velocity Planet Searcher spectrograph, technological advances for precision radial velocity (RV) measurements have focused on building extremely stable instruments. To reach still higher precision, future spectrometers will need to improve upon the state of the art, producing even higher fidelity spectra. This should be possible with improved environmental control, greater stability in the illumination of the spectrometer optics, better detectors, more precise wavelength calibration, and broader bandwidth spectra. Key data analysis challenges for the precision RV community include distinguishing center of mass (COM) Keplerian motion from photospheric velocities (time correlated noise) and the proper treatment of telluric contamination. Success here is coupled to the instrument design, but also requires the implementation of robust statistical and modeling techniques. COM velocities produce Doppler shifts that affect every line identically, while photospheric velocities produce line profile asymmetries with wavelength and temporal dependencies that are different from Keplerian signals. Exoplanets are an important subfield of astronomy and there has been an impressive rate of discovery over the past two decades. However, higher precision RV measurements are required to serve as a discovery technique for potentially habitable worlds, to confirm and characterize detections from transit missions, and to provide mass measurements for other space-based missions. The future of exoplanet science has very different trajectories depending on the precision that

  3. Radial Velocity Data Analysis with Compressed Sensing Techniques

    NASA Astrophysics Data System (ADS)

    Hara, Nathan C.; Boué, G.; Laskar, J.; Correia, A. C. M.

    2016-09-01

    We present a novel approach for analysing radial velocity data that combines two features: all the planets are searched at once and the algorithm is fast. This is achieved by utilizing compressed sensing techniques, which are modified to be compatible with the Gaussian processes framework. The resulting tool can be used like a Lomb-Scargle periodogram and has the same aspect but with much fewer peaks due to aliasing. The method is applied to five systems with published radial velocity data sets: HD 69830, HD 10180, 55 Cnc, GJ 876 and a simulated very active star. The results are fully compatible with previous analysis, though obtained more straightforwardly. We further show that 55 Cnc e and f could have been respectively detected and suspected in early measurements from the Lick observatory and Hobby-Eberly Telescope available in 2004, and that frequencies due to dynamical interactions in GJ 876 can be seen.

  4. THE RADIAL VELOCITY EXPERIMENT (RAVE): FOURTH DATA RELEASE

    SciTech Connect

    Kordopatis, G.; Gilmore, G.; Steinmetz, M.; Williams, M. E. K.; Piffl, T.; Enke, H.; Carrillo, I.; Boeche, C.; Roeser, S.; Seabroke, G. M.; Siebert, A.; Zwitter, T.; Binney, J.; De Laverny, P.; Recio-Blanco, A.; Bijaoui, A.; Wyse, R. F. G.; Freeman, K.; Munari, U.; Anguiano, B.; and others

    2013-11-01

    We present the stellar atmospheric parameters (effective temperature, surface gravity, overall metallicity), radial velocities, individual abundances, and distances determined for 425,561 stars, which constitute the fourth public data release of the RAdial Velocity Experiment (RAVE). The stellar atmospheric parameters are computed using a new pipeline, based on the algorithms of MATISSE and DEGAS. The spectral degeneracies and the Two Micron All Sky Survey photometric information are now better taken into consideration, improving the parameter determination compared to the previous RAVE data releases. The individual abundances for six elements (magnesium, aluminum, silicon, titanium, iron, and nickel) are also given, based on a special-purpose pipeline that is also improved compared to that available for the RAVE DR3 and Chemical DR1 data releases. Together with photometric information and proper motions, these data can be retrieved from the RAVE collaboration Web site and the Vizier database.

  5. STARSPOT JITTER IN PHOTOMETRY, ASTROMETRY, AND RADIAL VELOCITY MEASUREMENTS

    SciTech Connect

    Makarov, V. V.; Beichman, C. A.; Lebreton, J.; Malbet, F.; Catanzarite, J. H.; Shao, M.; Fischer, D. A.

    2009-12-10

    Analytical relations are derived for the amplitude of astrometric, photometric, and radial velocity (RV) perturbations caused by a single rotating spot. The relative power of the starspot jitter is estimated and compared with the available data for kappa{sup 1} Ceti and HD 166435, as well as with numerical simulations for kappa{sup 1} Ceti and the Sun. A Sun-like star inclined at i = 90 deg. at 10 pc is predicted to have an rms jitter of 0.087 muas in its astrometric position along the equator, and 0.38 m s{sup -1} in radial velocities. If the presence of spots due to stellar activity is the ultimate limiting factor for planet detection, the sensitivity of SIM Lite to Earth-like planets in habitable zones is about an order of magnitude higher than the sensitivity of prospective ultra-precise RV observations of nearby stars.

  6. Short-period terrestrial planets and radial velocity stellar jitter.

    NASA Astrophysics Data System (ADS)

    Dumusque, Xavier

    2015-01-01

    Stellar jitter is the main limitation to ultra-precise radial velocity (RV) measurements. It currently precludes our ability to detect a planet like the Earth. Short-period terrestrial planets present first the advantage of inducing a stronger RV signal. In addition, the signal produced by these planets have a period completely different than stellar activity. This allows us, when the observational strategy is adequate, to decorrelate the planetary signal from the jitter induced by the star using filtering techniques. I will show the examples of Kepler-78b and Corot-7b, where the amplitude of the planetary signal can be detected, despite the stellar activity jitter that is 5 and 3 times larger, respectively. The cases of Alpha Cen Bb will also be reviewed, with a new reduction of the published data that increases the significance of the planetary signal.This project is funded by ETAEARTH, a transnational collaboration between European countries and the US (the Swiss Space Office, the Harvard Origin of Life Initiative, the Scottish Universities Physics Alliance, the University of Geneva, the Smithsonian Astrophysical Observatory, the Italian National Astrophysical Institute, the University of St. Andrews, Queens University Belfast, and the University of Edinburgh) setup to optimize the synergy between space-and ground-based data whose scientific potential for the characterization of extrasolar planets can only be fully exploited when analyzed together.

  7. Modelling nonstationary Doppler noise in exoplanetary radial velocity data

    NASA Astrophysics Data System (ADS)

    Baluev, Roman V.

    2015-08-01

    We construct a new class of analytic nonstationary noise models for exoplanetary Doppler data. The observable correlated noise is represented as a convolution of a parent activity process with a given memory function. The model honours the casuality principle, meaning that only past values of the activity may affect the observable value. This model does not approximate detailedly any real stellar activity phenomena, but it becomes mathematically simple, simultaneously satisfying the basic natural principles of physical sensibility and self-consistency.Additionally, we develop a new type of periodograms that can be used to detect periodic modulations in the Doppler noise characteristics, rather than in the observed radial velocity curve itself. We present first results of applying this technique to public Doppler time series available for a set of planet-hosting stars.This work was supported by the Russian Foundation for Basic Research (project No. 14-02-92615 KO_a), the UK Royal Society International Exchange grant IE140055, by the President of Russia grant for young scientists (No. MK-733.2014.2), by the programme of the Presidium of Russian Academy of Sciences P21, and by the Saint Petersburg State University research grant 6.37.341.2015.

  8. New measurements of radial velocities in clusters of galaxies. II

    NASA Astrophysics Data System (ADS)

    Proust, D.; Mazure, A.; Sodre, L.; Capelato, H.; Lund, G.

    1988-03-01

    Heliocentric radial velocities are determined for 100 galaxies in five clusters, on the basis of 380-518-nm observations obtained using a CCD detector coupled by optical fibers to the OCTOPUS multiobject spectrograph at the Cassegrain focus of the 3.6-m telescope at ESO La Silla. The data-reduction procedures and error estimates are discussed, and the results are presented in tables and graphs and briefly characterized.

  9. An extensive radial velocity survey towards NGC 6253

    NASA Astrophysics Data System (ADS)

    Montalto, M.; Melo, C. H. F.; Santos, N. C.; Queloz, D.; Piotto, G.; Desidera, S.; Bedin, L. R.; Momany, Y.; Saviane, I.

    2016-04-01

    The old and metal-rich open cluster NGC 6253 was observed with the Fibre Large Array Multi Element Spectrograph (FLAMES) multi-object spectrograph during an extensive radial velocity campaign monitoring 317 stars with a median of 15 epochs per object. All the targeted stars are located along the upper main sequence of the cluster between 14.8 < V < 16.5. Fifty nine stars are confirmed cluster members both by radial velocities and proper motions and do not show evidence of variability. We detected 45 variable stars among which 25 belong to NGC 6253. We were able to derive an orbital solution for four cluster members (and for two field stars) yielding minimum masses in between ˜90 MJ and ˜460 MJ and periods between 3 and 220 d. Simulations demonstrated that this survey was sensitive to objects down to 30 MJ at 10 days orbital periods with a detection efficiency equal to 50 per cent. On the basis of these results we concluded that the observed frequency of binaries down to the hydrogen burning limit and up to 20 d orbital period is around (1.5 ± 1.3) per cent in NGC 6253. The overall observed frequency of binaries around the sample of cluster stars is (13 ± 3) per cent. The median radial velocity precision achieved by the GIRAFFE spectrograph in this magnitude range was around ˜240 m s- 1 (˜180 m s- 1 for UVES). Based on a limited follow-up analysis of seven stars in our sample with the High Accuracy Radial velocity Planet Searcher (HARPS) spectrograph we determined that a precision of 35 m s- 1 can be reached in this magnitude range, offering the possibility to further extend the variability analysis into the substellar domain. Prospects are even more favourable once considering the upcoming ESPRESSO spectrograph at VLT.

  10. Radial Velocity Detection of Extra-Solar Planetary Systems

    NASA Technical Reports Server (NTRS)

    Cochran, William D.

    1998-01-01

    The McDonald Observatory Planetary Search (MOPS) was designed to search for Jovian-mass planets in orbit around solar-type stars by making high-precision measurements of the Radial Velocity (RV) of a star, to attempt to detect the reflex orbital motion of the star around the star-planet barycenter. In our solar system, the velocity of the Sun around the Sun-Jupiter barycenter averages 12.3 m/ s. The MOPS survey started operation in September 1987, and searches 36 bright, nearby, solar-type dwarfs to 10 m/s precision. The survey was started using telluric O2 absorption lines as the velocity reference metric. Observations use the McDonald Observatory 2.7-m Harlan Smith Telescope coude spectrograph with the six-foot camera. This spectrograph configuration isolates a single order of the echelle grating on a Texas Instruments 800 x 800 CCD. The telluric line method gave us a routine radial velocity precision of about 15 m/s for stars down to about 5-th magnitude. However, the data obtained with this technique suffered from some source of long-term systematic errors, which was probably the intrinsic velocity variability of the terrestrial atmosphere, i.e. winds. In order to eliminate this systematic error and to improve our overall measurement precision, we installed a stabilized I2 gas absorption cell as the velocity metric for the MOPS in October 1990. In use at the telescope, the cell is placed directly in front of the spectrograph entrance slit, with starlight passing through the cell. The use of this sealed stabilized I2 cell removes potential problems with possible long-term drifts in the velocity metric. The survey now includes a sample of 36 nearby F, G, and K type stars of luminosity class V or IV-V.

  11. RADIAL VELOCITY CONFIRMATION OF A BINARY DETECTED FROM PULSE TIMINGS

    SciTech Connect

    Barlow, B. N.; Dunlap, B. H.; Clemens, J. C.

    2011-08-10

    A periodic variation in the pulse timings of the pulsating hot subdwarf B (sdB) star CS 1246 was recently discovered via the observed minus calculated (O-C) diagram and suggests the presence of a binary companion with an orbital period of two weeks. Fits to this phase variation, when interpreted as orbital reflex motion, imply CS 1246 orbits a barycenter 11 lt-s away with a velocity of 16.6 km s{sup -1}. Using the Goodman spectrograph on the SOAR telescope, we decided to confirm this hypothesis by obtaining radial velocity measurements of the system over several months. Our spectra reveal a velocity variation with amplitude, period, and phase in accordance with the O-C diagram predictions. This corroboration demonstrates that the rapid pulsations of hot sdB stars can be adequate clocks for the discovery of binary companions via the pulse timing method.

  12. VizieR Online Data Catalog: Solar like stars radial velocities (Zechmeister+, 2013)

    NASA Astrophysics Data System (ADS)

    Zechmeister, M.; Kuerster, M.; Endl, M.; Lo Curto, G.; Hartman, H.; Nilsson, H.; Henning, T.; Hatzes, A. P.; Cochran, W. D.

    2012-11-01

    The catalogue is composed of radial velocity timeseries for 31 stars obtained with three instruments (CES+LC,CES+VLC,HARPS). Additionally the HARPS timeseries include activity indicators (logR'HK and Bisector span, FWHM, and Contrast of the cross correlation function). (4 data files).

  13. Bok Prize Lecture (shared) The Brown Dwarf Radial Velocity Survey

    NASA Astrophysics Data System (ADS)

    Charbonneau, Dave

    2004-03-01

    The swarm of nearby brown dwarfs and very low mass stars is an attractive sample for radial velocity monitoring. Such work is best conducted with an echelle spectrograph operating at infrared wavelengths where these objects(i) are most luminous, (ii) have a forest of molecular features, providing an excellent velocity metric, and {iii) are superimposed on the telluric spectrum, which yields the requisite wavelength calibration. I will present first results from such a survey, with a precision sufficient to detect Jupiter-mass planets with orbital periods of less than a year. Should such systems be uncovered, the planets would be amenable to direct study, due to system proximity, and the favorable contrast ratio between the planet and parent object.

  14. A Goldilocks principle for modelling radial velocity noise

    NASA Astrophysics Data System (ADS)

    Feng, F.; Tuomi, M.; Jones, H. R. A.; Butler, R. P.; Vogt, S.

    2016-09-01

    The Doppler measurements of stars are diluted and distorted by stellar activity noise. Different choices of noise models and statistical methods have led to much controversy in the confirmation of exoplanet candidates obtained through analysing radial velocity data. To quantify the limitation of various models and methods, we compare different noise models and signal detection criteria for various simulated and real data sets in the Bayesian framework. According to our analyses, the white noise model tend to interpret noise as signal, leading to false positives. On the other hand, the red noise models are likely to interpret signal as noise, resulting in false negatives. We find that the Bayesian information criterion combined with a Bayes factor threshold of 150 can efficiently rule out false positives and confirm true detections. We further propose a Goldilocks principle aimed at modelling radial velocity noise to avoid too many false positives and too many false negatives. We propose that the noise model with RHK-dependent jitter is used in combination with the moving average model to detect planetary signals for M dwarfs. Our work may also shed light on the noise modelling for hotter stars, and provide a valid approach for finding similar principles in other disciplines.

  15. Improve Radial Velocity Precision with Better Data Analysis Tools

    NASA Astrophysics Data System (ADS)

    Xuesong Wang, Sharon; Wright, Jason; Zhao, Ming

    2015-12-01

    The synergy between Kepler and the ground-based radial velocity (RV) surveys have made numerous discoveries of low-mass exoplanets, opening the age of Earth analogs. However, Earth analogs such as Kepler 452-b require a much higher RV precision ( ~ 10 cm/s) than the achievable with current instruments (~ 1 m/s) and understanding of stellar photosphere. This presentation will cover some of the instrumental and data issues that are currently hindering us from achieving the sub 1 m/s precision, as well as remedies and ways forward with future RV instruments. Highlights of our work include: (1) how telluric contamination affects RV precision and how to "telluric-proof" a Doppler pipeline; (2) how errors in the deconvolved stellar reference spectrum can mimic the signal of a super-Earth on a ~1 year orbit; (3) the battle with imperfections in the iodine reference spectra and how an ultra-high resolution (R ~ 500,000) echelle spectrum can help; (4) and a new RV extraction code in Python which incorporates MCMC and Gaussian Processes. This research is based on radial velocity data taken with iodine cell calibrators using Keck/HIRES and HET/HRS.

  16. Radial velocity planet detection biases at the stellar rotational period

    NASA Astrophysics Data System (ADS)

    Vanderburg, Andrew; Plavchan, Peter; Johnson, John Asher; Ciardi, David R.; Swift, Jonathan; Kane, Stephen R.

    2016-07-01

    Future generations of precise radial velocity (RV) surveys aim to achieve sensitivity sufficient to detect Earth mass planets orbiting in their stars' habitable zones. A major obstacle to this goal is astrophysical RV noise caused by active areas moving across the stellar limb as a star rotates. In this paper, we quantify how stellar activity impacts exoplanet detection with radial velocities as a function of orbital and stellar rotational periods. We perform data-driven simulations of how stellar rotation affects planet detectability and compile and present relations for the typical time-scale and amplitude of stellar RV noise as a function of stellar mass. We show that the characteristic time-scales of quasi-periodic RV jitter from stellar rotational modulations coincides with the orbital period of habitable-zone exoplanets around early M-dwarfs. These coincident periods underscore the importance of monitoring the targets of RV habitable-zone planet surveys through simultaneous photometric measurements for determining rotation periods and activity signals, and mitigating activity signals using spectroscopic indicators and/or RV measurements at different wavelengths.

  17. Binary Properties from Cepheid Radial Velocities (CRaV)

    NASA Astrophysics Data System (ADS)

    Evans, Nancy Remage; Berdnikov, Leonid; Lauer, Jennifer; Morgan, Douglas; Nichols, Joy; Günther, H. Moritz; Gorynya, Natalya; Rastorguev, Alexey; Moskalik, Pawel

    2015-07-01

    We have examined high accuracy radial velocities of Cepheids to determine the binary frequency. The data are largely from the CORAVEL spectrophotometer and the Moscow version, with a typical uncertainty of ≤slant 1 km s-1, and a time span from 1 to 20 years. A systemic velocity was obtained by removing the pulsation component using a high order Fourier series. From this data we have developed a list of stars showing no orbital velocity larger than ±1 km s-1. The binary fraction was analyzed as a function of magnitude, and yields an apparent decrease in this fraction for fainter stars. We interpret this as incompleteness at fainter magnitudes, and derive the preferred binary fraction of 29% ± 8% (20% ± 6% per decade of orbital period) from the brightest 40 stars. A comparison of this fraction in this period range (1-20 years) implies a large fraction for the full period range. This is reasonable in that the high accuracy velocities are sensitive to the longer periods and smaller orbital velocity amplitudes in the period range sampled here. Thus the Cepheid velocity sample provides a sensitive detection in the period range between short period spectroscopic binaries and resolved companions. The recent identification of δ Cep as a binary with very low amplitude and high eccentricity underscores the fact that the binary fractions we derive are lower limits, to which other low amplitude systems will probably be added. The mass ratio (q) distribution derived from ultraviolet observations of the secondary is consistent with a flat distribution for the applicable period range (1-20 years).

  18. Precise Radial Velocity Measurements for Kepler Giants Hosting Planetary Candidates: Kepler-91 and KOI-1894

    NASA Astrophysics Data System (ADS)

    Sato, Bun'ei; Hirano, Teruyuki; Omiya, Masashi; Harakawa, Hiroki; Kobayashi, Atsushi; Hasegawa, Ryo; Takarada, Takuya; Kawauchi, Kiyoe; Masuda, Kento

    2015-03-01

    We present results of radial-velocity follow-up observations for the two Kepler evolved stars Kepler-91 (KOI-2133) and KOI-1894, which had been announced as candidates to host transiting giant planets, with the Subaru 8.2 m telescope and the High Dispersion Spectrograph (HDS). By global modeling of the high-precision radial-velocity data taken with Subaru/HDS and photometric data taken by the Kepler mission accounting for orbital brightness modulations (ellipsoidal variations, reflected/emitted light, etc.) of the host stars, we independently confirmed that Kepler-91 hosts a transiting planet with a mass of 0.66 {{M}Jup}(Kepler-91b), and newly detected an offset of ˜20 m s-1 between the radial velocities taken at ˜1 yr interval, suggesting the existence of an additional companion in the system. As for KOI-1894, we detected possible phased variations in the radial velocities and light curves with 2-3σ confidence level, which could be explained as a reflex motion and ellipsoidal variation of the star caused by a transiting sub-Saturn-mass (˜0.18 {{M}Jup}) planet.

  19. RUNAWAY STARS, HYPERVELOCITY STARS, AND RADIAL VELOCITY SURVEYS

    SciTech Connect

    Bromley, Benjamin C.; Kenyon, Scott J.; Brown, Warren R.; Geller, Margaret J. E-mail: skenyon@cfa.harvard.ed E-mail: mgeller@cfa.harvard.ed

    2009-12-01

    Runaway stars ejected from the Galactic disk populate the halo of the Milky Way. To predict the spatial and kinematic properties of runaways, we inject stars into a Galactic potential, compute their trajectories through the Galaxy, and derive simulated catalogs for comparison with observations. Runaways have a flattened spatial distribution, with higher velocity stars at Galactic latitudes less than 30{sup 0}. Due to their shorter stellar lifetimes, massive runaway stars are more concentrated toward the disk than low mass runaways. Bound (unbound) runaways that reach the halo probably originate from distances of 6-12 kpc (10-15 kpc) from the Galactic center, close to the estimated origin of the unbound runaway star HD 271791. Because runaways are brighter and have smaller velocities than hypervelocity stars (HVSs), radial velocity surveys are unlikely to confuse runaway stars with HVSs. We estimate that at most one runaway star contaminates the current sample. We place an upper limit of 2% on the fraction of A-type main-sequence stars ejected as runaways.

  20. Comparison of CME radial velocities from a flux rope model and an ice cream cone model

    NASA Astrophysics Data System (ADS)

    Kim, T.; Moon, Y.; Na, H.

    2011-12-01

    Coronal Mass Ejections (CMEs) on the Sun are the largest energy release process in the solar system and act as the primary driver of geomagnetic storms and other space weather phenomena on the Earth. So it is very important to infer their directions, velocities and three-dimensional structures. In this study, we choose two different models to infer radial velocities of halo CMEs since 2008 : (1) an ice cream cone model by Xue et al (2005) using SOHO/LASCO data, (2) a flux rope model by Thernisien et al. (2009) using the STEREO/SECCHI data. In addition, we use another flux rope model in which the separation angle of flux rope is zero, which is morphologically similar to the ice cream cone model. The comparison shows that the CME radial velocities from among each model have very good correlations (R>0.9). We will extending this comparison to other partial CMEs observed by STEREO and SOHO.

  1. A radial velocity study of the dwarf nova TZ Persei

    NASA Astrophysics Data System (ADS)

    Ringwald, F. A.

    1995-05-01

    A radial velocity study of the Hα emission line of the dwarf nova TZ Per is presented. TZ Per has a spectroscopic period of 6.2520+/-0.0096h. With this period and published JHK photometry, a distance of >~380 pc is inferred. This Z Cam star has both slow outbursts and a short outburst cycle, and time-resolved spectra were obtained on both the rise and the decline of a dwarf nova outburst. TZ Per does not obey the relation between orbital period and outburst decline time found by Bailey and calibrated by Szkody & Mattei. This is probably because the disc is hot all the time, relative to dwarf novae such as U Gem or SS Cyg.

  2. Lyman-Alpha Observations of High Radial Velocity Stars

    NASA Astrophysics Data System (ADS)

    Bookbinder, Jay

    1990-12-01

    H I LYMAN -ALPHA (LY-A) IS ONE OF THE MOST IMPORTANT LINES EMITTED BY PLASMA IN THE TEMPERATURE RANGE OF 7000 TO 10 TO THE FIFTH POWER K IN LATE-TYPE STARS. IT IS A MAJOR COMPONENT OF THE TOTAL RADIATIVE LOSS RATE, AND IT PLAYS A CRUCIAL ROLE IN DETERMINING THE ATMOSPHERIC STRUCTURE AND IN FLUORESCING OTHER UV LINES. YET IT IS ALSO THE LEAST STUDIED MAJOR LINE IN THE FAR UV, BECAUSE MOST OF THE LINE FLUX IS ABSORBED BY THE ISM ALONG THE LINE OF SIGHT AND BECAUSE IT IS STRONGLY COMTAMINATED BY THE GEOCORONAL BACKGROUND. A KNOWLEDGE OF THE Ly-A PROFILE IS ALSO IMPORTANT FOR STUDIES OF DEUTERIUM IN THE INTERSTELLAR MEDIUM. BY OBSERVING HIGH RADIAL VELOCITY STARS WE WILL OBTAIN FOR THE FIRST TIME HIGH RESOLUTION SPECTRA OF THE CORE OF A STELLAR H I LYMAN-A EMISSION LINE PROFILE.

  3. Correcting Radial Velocities for Long-Term Magnetic Activity Variations.

    PubMed

    Saar; Fischer

    2000-05-01

    We study stars in the Lick planetary survey for correlations between simultaneous measurements of high-precision radial velocities vr and magnetic activity (as measured in an SIR emission index from Ca ii lambda8662). We find significant correlations in approximately 30% of the stars. After removing linear trends between SIR and vr, we find that the dispersion in vr in these stars is decreased by an average of 17%, or approximately 45% of the dispersion above the measurement noise. F stars and less active stars with variable Ca ii H and K lines are the most successfully corrected. The magnitude of the slope of the SIR versus vr relations increases proportional to vsini and (excepting M dwarfs) tends to decrease with decreasing Teff. We argue that the main cause of these effects is modification of the mean line bisector shape brought on by long-term, magnetic activity-induced changes in the surface brightness and convective patterns. The correlations can be used to partially correct vr data for the effects of long-term activity variations, potentially permitting study of planets around some (higher mass) younger stars and planets producing smaller stellar reflex velocities. PMID:10790082

  4. KECK NIRSPEC RADIAL VELOCITY OBSERVATIONS OF LATE-M DWARFS

    SciTech Connect

    Tanner, Angelle; White, Russel; Bailey, John; Blake, Cullen; Blake, Geoffrey; Cruz, Kelle; Burgasser, Adam J.; Kraus, Adam

    2012-11-15

    We present the results of an infrared spectroscopic survey of 23 late-M dwarfs with the NIRSPEC echelle spectrometer on the Keck II telescope. Using telluric lines for wavelength calibration, we are able to achieve measurement precisions of down to 45 m s{sup -1} for our late-M dwarfs over a one- to four-year long baseline. Our sample contains two stars with radial velocity (RV) variations of >1000 m s{sup -1}. While we require more measurements to determine whether these RV variations are due to unseen planetary or stellar companions or are the result of starspots known to plague the surface of M dwarfs, we can place upper limits of <40 M{sub J} sin i on the masses of any companions around those two M dwarfs with RV variations of <160 m s{sup -1} at orbital periods of 10-100 days. We have also measured the rotational velocities for all the stars in our late-M dwarf sample and offer our multi-order, high-resolution spectra over 2.0-2.4 {mu}m to the atmospheric modeling community to better understand the atmospheres of late-M dwarfs.

  5. Correcting Radial Velocities for Long-Term Magnetic Activity Variations.

    PubMed

    Saar; Fischer

    2000-05-01

    We study stars in the Lick planetary survey for correlations between simultaneous measurements of high-precision radial velocities vr and magnetic activity (as measured in an SIR emission index from Ca ii lambda8662). We find significant correlations in approximately 30% of the stars. After removing linear trends between SIR and vr, we find that the dispersion in vr in these stars is decreased by an average of 17%, or approximately 45% of the dispersion above the measurement noise. F stars and less active stars with variable Ca ii H and K lines are the most successfully corrected. The magnitude of the slope of the SIR versus vr relations increases proportional to vsini and (excepting M dwarfs) tends to decrease with decreasing Teff. We argue that the main cause of these effects is modification of the mean line bisector shape brought on by long-term, magnetic activity-induced changes in the surface brightness and convective patterns. The correlations can be used to partially correct vr data for the effects of long-term activity variations, potentially permitting study of planets around some (higher mass) younger stars and planets producing smaller stellar reflex velocities.

  6. A radial velocity study of the intermediate polar EX Hydrae

    NASA Astrophysics Data System (ADS)

    Echevarría, J.; Ramírez-Torres, A.; Michel, R.; Hernández Santisteban, J. V.

    2016-09-01

    A study on the intermediate polar EX Hya is presented, based on simultaneous photometry and high-dispersion spectroscopic observations, during four consecutive nights. The strong photometric modulation related to the 67-min spin period of the primary star is clearly present, as well as the narrow eclipses associated with the orbital modulation. Since our eclipse timings have been obtained almost 91 000 cycles since the last reported observations, we present new linear ephemeris, although we cannot rule out a sinusoidal variation suggested by previous authors. The system shows double-peaked H α, H β and He I λ5876 Å emission lines, with almost no other lines present. As H α is the only line with enough S/N ratio in our observations, we have concentrated our efforts in its study, in order to obtain a reliable radial velocity semi-amplitude. From the profile of this line, we find two important components; one with a steep rise and velocities not larger than ˜1000 km s-1 and another broader component extending up to ˜2000 km s-1, which we interpret as coming mainly from the inner disc. A strong and variable hotspot is found and a stream-like structure is seen at times. We show that the best solution correspond to K1 = 58 ± 5 km s-1 from H α, from the two emission components, which are both in phase with the orbital modulation. We remark on a peculiar effect in the radial velocity curve around phase zero, which could be interpreted as a Rositter-MacLaughlin-like effect, which has been taken into account before deriving K1. This value is compatible with the values found in high resolution both in the ultraviolet and X-ray. Using the published inclination angle of i =78° ± 1° and semi-amplitude K2 = 432 ± 5 km s-1, we find: M1 = 0.78 ± 0.03 M⊙, M2 = 0.10 ± 0.02 M⊙ and a = 0.67 ± 0.01 R⊙. Doppler Tomography has been applied, to construct six Doppler tomograms for single orbital cycles spanning the four days of observations to support our conclusions

  7. VizieR Online Data Catalog: Abell 3733 radial velocities (Solanes+ 1998)

    NASA Astrophysics Data System (ADS)

    Solanes, J. M.; Stein, P.

    1998-03-01

    Cross-correlation and emission-line heliocentric radial velocities for 112 galaxies observed with the MEFOS and OPTOPUS spectrographs in the field of the galaxy cluster A3733. The last column lists the final radial velocities which result form a weighted average of the velocity data in the previous columns. (1 data file).

  8. Searching for Radial Velocity Variations in eta Carinae

    NASA Technical Reports Server (NTRS)

    Iping, R. C.; Sonneborn, G.; Gull, T. R.; Ivarsson, S.; Nielsen, K.

    2006-01-01

    A hot companion of eta Carinae has been detected using high resolution spectra (905 - 1180 A) obtained with the Far Ultraviolet Spectroscopic Explorer (FUSE) satellite (see poster by Sonneborn et al.). Analysis of the far-UV spectrum shows that eta Car B is a luminous hot star. The N II 1084-86 emission feature indicates that the star may be nitrogen rich. The FUV continuum and the S IV 1073 P-Cygni wind line suggest that the effective temperature of eta Car B is at least 25,000 K. FUV spectra of eta Carinae were obtained with the FUSE satellite at 9 epochs between 2000 February and 2005 July. The data consists of 12 observations taken with the LWRS aperture (30x30 arcsec), three with the HIRS aperture (1.25x20 arcsec), and one MRDS aperture (4x20 arcsec). In this paper we discuss the analysis of these spectra to search for radial velocity variations associated with the 5.54-year binary orbit of Eta Car AB.

  9. Photonic systems for high precision radial velocity measurements

    NASA Astrophysics Data System (ADS)

    Halverson, Samuel

    2016-01-01

    I will discuss new instrumentation and techniques designed to maximize the Doppler radial velocity (RV) measurement precision of next generation exoplanet discovery instruments. These systems include a novel wavelength calibration device based on an all-fiber fabry-perot interferometer, a compact and efficient optical fiber image scrambler based on a single high-index ball lens, and a unique optical fiber mode mixer. These systems have been developed specifically to overcome three technological hurdles that have classically hindered high precision RV measurements in both the optical and near-infrared (NIR), namely: lack of available wavelength calibration sources, inadequate decoupling of the spectrograph from variable telescope illumination, and speckle-induced noise due to mode interference in optical fibers. The instrumentation presented here will be applied to the Habitable-zone Planet Finder, a NIR RV instrument designed to detect rocky planets orbiting in the habitable zones of nearby M-dwarfs, and represents a critical technological step towards the detection of potentially habitable Earth-like planets. While primarily focused in the NIR, many of these systems will be adapted to future optical RV instruments as well, such as NASA's new Extreme Precision Doppler Spectrometer for the WIYN telescope.

  10. Estimating stellar radial velocity variability from Kepler and GALEX: Implications for the radial velocity confirmation of exoplanets

    SciTech Connect

    Cegla, H. M.; Watson, C. A.; Stassun, K. G.; Bastien, F. A.; Pepper, J.

    2014-01-01

    We cross match the GALEX and Kepler surveys to create a unique dataset with both ultraviolet (UV) measurements and highly precise photometric variability measurements in the visible light spectrum. As stellar activity is driven by magnetic field modulations, we have used UV emission from the magnetically heated gas in the stellar atmosphere to serve as our proxy for the more well-known stellar activity indicator, R' {sub HK}. The R' {sub HK} approximations were in turn used to estimate the level of astrophysical noise expected in radial velocity (RV) measurements and these were then searched for correlations with photometric variability. We find significant scatter in our attempts to estimate RV noise for magnetically active stars, which we attribute to variations in the phase and strength of the stellar magnetic cycle that drives the activity of these targets. However, for stars we deem to be magnetically quiet, we do find a clear correlation between photometric variability and estimated levels of RV noise (with variability up to ∼10 m s{sup –1}). We conclude that for these quiet stars, we can use photometric measurements as a proxy to estimate the RV noise expected. As a result, the procedure outlined in this paper may help select targets best-suited for RV follow-up necessary for planet confirmation.

  11. On the Voyager 1 Zero Radial Velocity Measurements in the Inner Heliosheath

    NASA Astrophysics Data System (ADS)

    Pogorelov, N. V.; Borovikov, S. N.; Kryukov, I.; Zank, G. P.

    2011-12-01

    Theoretical analysis of the Voyager 1 data revealed a very small, or even negative, value of the solar wind (SW) radial velocity component. This should not be surprising if we take into account time-dependent processes that take place in the inner heliosheath (IHS). We analyze solar cycle modeling of the SW interaction with the local interstellar medium (LISM) and demonstrate the existence of small and negative values of the SW radial velocity. It shown that, in reality, a similar picture can be observed in the outer heliosheath (OHS), where on the contrary, extended regions of the positive radial velocity are observed. Another scenario discussed in this talk is related to effects of transients, such as global merged interaction regions and corotating interacting regions. Numerical results are obtained with the SW-LISM interaction model developed in the UAHuntsville and implemented in the Multi-Scale Fluid-Kinetic Simulation Suite. This model treats ions magnetohydrodynamically while the transport of neutral atoms is performed kinetically by solving the Boltzmann equation with a Monte Carlo approach or using a multi-fluid approach developed in mid-90's by G. P. Zank. Pickup ions (PUIs) can be treated as a separate fluid. The evolution of the PUI-generated turbulence is addressed on the differential level by adding three additional equations, which are solved self-consistently with the MHD-kinetic system of equations.

  12. Uncovering the planets and stellar activity of CoRoT-7 using only radial velocities

    NASA Astrophysics Data System (ADS)

    Faria, J. P.; Haywood, R. D.; Brewer, B. J.; Figueira, P.; Oshagh, M.; Santerne, A.; Santos, N. C.

    2016-04-01

    Stellar activity can induce signals in the radial velocities of stars, complicating the detection of orbiting low-mass planets. We present a method to determine the number of planetary signals present in radial-velocity datasets of active stars, using only radial-velocity observations. Instead of considering separate fits with different number of planets, we use a birth-death Markov chain Monte Carlo algorithm to infer the posterior distribution for the number of planets in a single run. In a natural way, the marginal distributions for the orbital parameters of all planets are also inferred. This method is applied to HARPS data of CoRoT-7. We confidently recover the orbits of both CoRoT-7b and CoRoT-7c although the data show evidence for the presence of additional signals. All data and software presented in this article are available online at http://https://github.com/j-faria/exoBD-CoRoT7

  13. WHICH RADIAL VELOCITY EXOPLANETS HAVE UNDETECTED OUTER COMPANIONS?

    SciTech Connect

    Rodigas, Timothy J.; Hinz, Philip M.

    2009-09-01

    The observed radial velocity (RV) eccentricity distribution for extrasolar planets in single-planet systems shows that a significant fraction of planets are eccentric (e > 0.1). However, an RV planet's eccentricity, which comes from the Keplerian fitting, can be biased by low signal-to-noise ratio and poor sampling. Here, we investigate the effects on eccentricity produced by undetected outer companions. We have carried out Monte Carlo simulations of mock RV data to understand this effect and predict its impact on the observed distribution. We first quantify the statistical bias of known RV planets' eccentricities produced by undetected zero-eccentricity wide-separation companions and show that this effect alone cannot explain the observed distribution. We then modify the simulations to consist of two populations, one of zero-eccentricity planets in double-planet systems and the other of single planets drawn from an eccentric distribution. Our simulations show that a good fit to the observed distribution is obtained with 45% zero-eccentricity double planets and 55% single eccentric planets. Assuming that our two simulated populations of planets are a good approximation for the true RV population, matching the observed distribution allows us to determine the probability that a known RV planet's orbital eccentricity has been biased by an undetected wide-separation companion. Averaged over eccentricity we calculate this probability to be {approx}4%, suggesting that a small fraction of systems may have a yet to be discovered outer companion. Our simulations show that moderately eccentric planets, with 0.1 < e < 0.3 and 0.1 < e < 0.2, have a {approx}13% and {approx}19% probability, respectively, of having an undetected outer companion. We encourage both high-contrast direct imaging and RV follow-up surveys of known RV planets with moderate eccentricities to test our predictions and look for previously undetected outer companions.

  14. Extreme Precision Environmental Control for Next Generation Radial Velocity Spectrographs

    NASA Astrophysics Data System (ADS)

    Stefansson, Gudmundur K.; Hearty, Fred; Levi, Eric; Robertson, Paul; Mahadevan, Suvrath; Bender, Chad; Nelson, Matt; Halverson, Samuel

    2015-12-01

    Extreme radial velocity precisions of order 10cm/s will enable the discoveries of Earth-like planets around solar-type stars. Temperature and pressure variations inside a spectrograph can lead to thermomechanical instabilities in the optics and mounts, and refractive index variations in both the optical elements as well as the surrounding air. Together, these variations can easily induce instrumental drifts of several tens to hundreds of meters per second. Enclosing the full optical train in thermally stabilized high-vacuum environments minimizes such errors. In this talk, I will discuss the Environmental Control System (ECS) for the Habitable Zone Planet Finder (HPF) spectrograph: a near infrared (NIR) facility class instrument we will commission at the Hobby Eberly Telescope in 2016. The ECS will maintain the HPF optical bench stable at 180K at the sub milli-Kelvin level on the timescale of days, and at the few milli-Kelvin level over months to years. The entire spectrograph is kept under high-quality vacuum (<10-6 Torr), and environmental temperature fluctuations are compensated for with an actively controlled radiation shield outfitted with custom feedback electronics. High efficiency Multi-Layer Insulation (MLI) blankets, and a passive external thermal enclosure further isolate the optics from ambient perturbations. This environmental control scheme is versatile, suitable to stabilize both next generation NIR, and optical spectrographs. I will show how we are currently testing this control system for use with our design concept of the Extreme Precision Doppler Spectrograph (EPDS), the next generation optical spectrograph for the WIYN 3.5m telescope. Our most recent results from full-scale stability tests will be presented.

  15. Long-lived, long-period radial velocity variations in Aldebaran: A planetary companion and stellar activity

    NASA Astrophysics Data System (ADS)

    Hatzes, A. P.; Cochran, W. D.; Endl, M.; Guenther, E. W.; MacQueen, P.; Hartmann, M.; Zechmeister, M.; Han, I.; Lee, B.-C.; Walker, G. A. H.; Yang, S.; Larson, A. M.; Kim, K.-M.; Mkrtichian, , D. E.; Döllinger, M.; Simon, , A. E.; Girardi, L.

    2015-08-01

    Aims: We investigate the nature of the long-period radial velocity variations in α Tau first reported over 20 yr ago. Methods: We analyzed precise stellar radial velocity measurements for α Tau spanning over 30 yr. An examination of the Hα and Ca II λ8662 spectral lines, and Hipparcos photometry was also done to help discern the nature of the long-period radial velocity variations. Results: Our radial velocity data show that the long-period, low amplitude radial velocity variations are long-lived and coherent. Furthermore, Hα equivalent width measurements and Hipparcos photometry show no significant variations with this period. Another investigation of this star established that there was no variability in the spectral line shapes with the radial velocity period. An orbital solution results in a period of P = 628.96 ± 0.90 d, eccentricity, e = 0.10 ± 0.05, and a radial velocity amplitude, K = 142.1 ± 7.2 m s-1. Evolutionary tracks yield a stellar mass of 1.13 ± 0.11 M⊙, which corresponds to a minimum companion mass of 6.47 ± 0.53 MJup with an orbital semi-major axis of a = 1.46 ± 0.27 AU. After removing the orbital motion of the companion, an additional period of ≈520 d is found in the radial velocity data, but only in some time spans. A similar period is found in the variations in the equivalent width of Hα and Ca II. Variations at one-third of this period are also found in the spectral line bisector measurements. The ~520 d period is interpreted as the rotation modulation by stellar surface structure. Its presence, however, may not be long-lived, and it only appears in epochs of the radial velocity data separated by ~10 yr. This might be due to an activity cycle. Conclusions: The data presented here provide further evidence of a planetary companion to α Tau, as well as activity-related radial velocity variations. Based in part on observations obtained at the 2-m-Alfred Jensch Telescope at the Thüringer Landessternwarte Tautenburg and the

  16. STARSPOT-INDUCED OPTICAL AND INFRARED RADIAL VELOCITY VARIABILITY IN T TAURI STAR HUBBLE I 4

    SciTech Connect

    Mahmud, Naved I.; Johns-Krull, Christopher M.; Hartigan, Patrick M.; Crockett, Christopher J.; Prato, L.; Jaffe, Daniel T.; Beichman, Charles A. E-mail: cmj@rice.edu E-mail: crockett@lowell.edu E-mail: dtj@astro.as.utexas.edu

    2011-08-01

    We report optical ({approx}6150 A) and K-band (2.3 {mu}m) radial velocities obtained over two years for the pre-main-sequence weak-lined T Tauri star Hubble I 4. We detect periodic and near-sinusoidal radial velocity variations at both wavelengths, with a semi-amplitude of 1395 {+-} 94 m s{sup -1} in the optical and 365 {+-} 80 m s{sup -1} in the infrared. The lower velocity amplitude at the longer wavelength, combined with bisector analysis and spot modeling, indicates that there are large, cool spots on the stellar surface that are causing the radial velocity modulation. The radial velocities maintain phase coherence over hundreds of days suggesting that the starspots are long-lived. This is one of the first active stars where the spot-induced velocity modulation has been resolved in the infrared.

  17. Kepler beaming binaries radial velocity follow-up with WIYN/Hydra

    NASA Astrophysics Data System (ADS)

    Shporer, Avi; Stassun, Keivan; Faigler, Simchon; Boyajian, Tabetha; Mazeh, Tsevi; Tal-Or, Lev; Prsa, Andrej

    2015-12-01

    High-quality space-based time series photometry reveals the minute photometric modulations induced by orbital motion in short-period binary systems with stellar and substellar secondaries. Those modulations are induced by both gravitational and atmospheric processes. Gravitational processes include the beaming effect (aka Doppler boosting) and tidal ellipsoidal distortion, and the atmospheric processes include reflected light and thermal emission by the secondary atmosphere. Therefore, non-eclipsing (non-transiting) systems are detectable using photometry alone. The availability of Kepler data for a large sample of stars combined with the sensitivity to non-eclipsing systems (which are at least an order of magnitude more common than eclipsing systems) has the potential of transforming the Kepler survey into the equivalent of a radial velocity survey of a large sample of stars. This allows detecting intrinsically rare systems, where traditional approaches, e.g., radial velocity and transit surveys, are highly inefficient. Those include systems where the companion is a brown-dwarf or a massive planet, or even a white dwarf. As this approach is still in its infancy, we are carrying out radial velocity follow-up of Kepler photometric detections, to confirm the nature of the system and accurately measure the orbit and the companion’s mass. Here we present our results from an radial velocity campaign with the WIYN/Hydra multi-fiber spectrograph, where we used 26 nights during the 2014 and 2015 Kepler observing seasons to observe five Hydra one-degree diameter fields within the Kepler field. Our list of targets includes 131 Kepler beaming binaries, and we used additional fibers to observe 85 Kepler eclipsing binaries and 31 Kepler Objects of Interest (KOIs). A detailed comparison between the photometrically predicted companion’s mass and the mass measured through radial velocities will improve our understanding of this young approach, and will support similar projects

  18. Developing gradient metal alloys through radial deposition additive manufacturing.

    PubMed

    Hofmann, Douglas C; Roberts, Scott; Otis, Richard; Kolodziejska, Joanna; Dillon, R Peter; Suh, Jong-ook; Shapiro, Andrew A; Liu, Zi-Kui; Borgonia, John-Paul

    2014-01-01

    Interest in additive manufacturing (AM) has dramatically expanded in the last several years, owing to the paradigm shift that the process provides over conventional manufacturing. Although the vast majority of recent work in AM has focused on three-dimensional printing in polymers, AM techniques for fabricating metal alloys have been available for more than a decade. Here, laser deposition (LD) is used to fabricate multifunctional metal alloys that have a strategically graded composition to alter their mechanical and physical properties. Using the technique in combination with rotational deposition enables fabrication of compositional gradients radially from the center of a sample. A roadmap for developing gradient alloys is presented that uses multi-component phase diagrams as maps for composition selection so as to avoid unwanted phases. Practical applications for the new technology are demonstrated in low-coefficient of thermal expansion radially graded metal inserts for carbon-fiber spacecraft panels.

  19. Developing Gradient Metal Alloys through Radial Deposition Additive Manufacturing

    PubMed Central

    Hofmann, Douglas C.; Roberts, Scott; Otis, Richard; Kolodziejska, Joanna; Dillon, R. Peter; Suh, Jong-ook; Shapiro, Andrew A.; Liu, Zi-Kui; Borgonia, John-Paul

    2014-01-01

    Interest in additive manufacturing (AM) has dramatically expanded in the last several years, owing to the paradigm shift that the process provides over conventional manufacturing. Although the vast majority of recent work in AM has focused on three-dimensional printing in polymers, AM techniques for fabricating metal alloys have been available for more than a decade. Here, laser deposition (LD) is used to fabricate multifunctional metal alloys that have a strategically graded composition to alter their mechanical and physical properties. Using the technique in combination with rotational deposition enables fabrication of compositional gradients radially from the center of a sample. A roadmap for developing gradient alloys is presented that uses multi-component phase diagrams as maps for composition selection so as to avoid unwanted phases. Practical applications for the new technology are demonstrated in low-coefficient of thermal expansion radially graded metal inserts for carbon-fiber spacecraft panels. PMID:24942329

  20. The effect of non-zero radial velocity on the impulse and circulation of starting jets

    NASA Astrophysics Data System (ADS)

    Krieg, Michael; Mohseni, Kamran

    2011-11-01

    Vortex ring formation dynamics are generally studied using two basic types of vortex generators. Piston cylinder vortex generators eject fluid through a long tube which ensures a purely axial jet; whereas, vortex ring generators which expel fluid through a flat plate with a circular orifice produce 2-D jets (non-zero radial velocity). At the nozzle exit plane of the orifice type vortex generator the radial component of velocity is linearly proportional to the radial distance from the axis of symmetry, reaching a maximum at the edge of the orifice with a magnitude around 10 % of the piston velocity (the ratio of the volume flux and the nozzle area). As the jet advances downstream the radial velocity quickly dissipates, and becomes purely axial less than a diameter away from the nozzle exit plane. The radial velocity gradient in the axial direction plays a key role in the rate at which circulation and impulse are ejected from the vortex generator. Though the radial component of velocity is small compared to the axial velocity, it has a significant effect on both the circulation and impulse of the starting jet because of this gradient. The extent of circulation and impulse enhancement is investigated through experimental DPIV data showing that the orifice device produces nearly double both circulation and energy (with identical piston velocity and stroke ratios).

  1. VizieR Online Data Catalog: Radial velocities of GJ 674 (Bonfils+, 2007)

    NASA Astrophysics Data System (ADS)

    Bonfils, X.; Mayor, M.; Delfosse, X.; Forveille, T.; Gillon, M.; Perrier, C.; Udry, S.; Bouchy, F.; Lovis, C.; Pepe, F.; Queloz, D.; Santos, N. C.; Bertaux, J.-L.

    2007-10-01

    The paper reports the discovery of a 11M{earth} planet orbiti nearby M dwarf GJ 674. The paper also shows the star has a spot on its surface. The spot modulates the radial-velocity, the photometric measurements as well as the spectroscopic indices. Here we list the radial-velocity data measured with HARPS (a high-resolution spectrograph providing high precision radial velocities), the spectroscopic indices measured on the same spectra gathered with HARPS and the photometric measurements gathered with the C2 Camera of the EULER Telescope. (3 data files).

  2. Radial velocity variations in the young eruptive star EX Lupi

    NASA Astrophysics Data System (ADS)

    Kóspál, Á.; Mohler-Fischer, M.; Sicilia-Aguilar, A.; Ábrahám, P.; Curé, M.; Henning, Th.; Kiss, Cs.; Launhardt, R.; Moór, A.; Müller, A.

    2014-01-01

    Context. EX Lup-type objects (EXors) are low-mass pre-main sequence objects characterized by optical and near-infrared outbursts attributed to highly enhanced accretion from the circumstellar disk onto the star. Aims: The trigger mechanism of EXor outbursts is still debated. One type of theory requires a close (sub)stellar companion that perturbs the inner part of the disk and triggers the onset of the enhanced accretion. Here, we study the radial velocity (RV) variations of EX Lup, the prototype of the EXor class, and test whether they can be related to a close companion. Methods: We conducted a five-year RV survey, collecting 54 observations with HARPS and FEROS. We analyzed the activity of EX Lup by checking the bisector, the equivalent width of the Ca 8662 Å line, the asymmetry of the Ca II K line, the activity indicator SFEROS, the asymmetry of the cross-correlation function, the line depth ratio of the VI/FeI lines, and the TiO, CaH 2, CaH 3, CaOH, and Hα indices. We complemented the RV measurements with a 14-day optical/infrared photometric monitoring to look for signatures of activity or varying accretion. Results: We found that the RV of EX Lup is periodic (P = 7.417 d), with stable period, semi-amplitude (2.2 km s-1), and phase over at least four years of observations. This period is not present in any of the above-mentioned activity indicators. However, the RVs of narrow metallic emission lines suggest the same period, but with an anti-correlating phase. The observed absorption line RVs can be fitted with a Keplerian solution around a 0.6 M⊙ central star with msini = (14.7 ± 0.7) MJup and eccentricity of e = 0.24. Alternatively, we attempted to model the observations with a cold or hot stellar spot as well. We found that in our simple model, the spot parameters needed to reproduce the RV semi-amplitude are in contradiction with the photometric variability, making the spot scenario unlikely. Conclusions: We qualitatively discuss two possibilities to

  3. Quasilinear model for energetic particle diffusion in radial and velocity space

    NASA Astrophysics Data System (ADS)

    Waltz, R. E.; Bass, E. M.; Staebler, G. M.

    2013-04-01

    A quasilinear model for passive energetic particle (EP) turbulent diffusion in radial and velocity space is fitted and tested against nonlinear gyrokinetic tokamak simulations with the GYRO code [J. Candy and R. E. Waltz, Phys. Rev. Lett. 91, 045001 (2003)]. Off diagonal elements of a symmetric positive definite 2×2 EP diffusion matrix account for fluxes up radial (energy) gradients driven by energy (radial) gradients of the EP velocity space distribution function. The quasilinear ratio kernel of the model is provided by a simple analytic formula for the EP radial and velocity space EP diffusivity relative to radial thermal ion energy diffusivity at each linear mode of the turbulence driven by the thermal plasma. The TGLF [G. M. Staebler, J. E. Kinsey, and R. E. Waltz, Phys. Plasmas 14, 0055909 (2007); ibid. 15, 0055908 (2008)] tokamak transport model provides the linear mode frequency and growth rates to the kernel as well as the nonlinear spectral weight for each mode.

  4. Quasilinear model for energetic particle diffusion in radial and velocity space

    SciTech Connect

    Waltz, R. E.; Staebler, G. M.; Bass, E. M.

    2013-04-15

    A quasilinear model for passive energetic particle (EP) turbulent diffusion in radial and velocity space is fitted and tested against nonlinear gyrokinetic tokamak simulations with the GYRO code [J. Candy and R. E. Waltz, Phys. Rev. Lett. 91, 045001 (2003)]. Off diagonal elements of a symmetric positive definite 2 Multiplication-Sign 2 EP diffusion matrix account for fluxes up radial (energy) gradients driven by energy (radial) gradients of the EP velocity space distribution function. The quasilinear ratio kernel of the model is provided by a simple analytic formula for the EP radial and velocity space EP diffusivity relative to radial thermal ion energy diffusivity at each linear mode of the turbulence driven by the thermal plasma. The TGLF [G. M. Staebler, J. E. Kinsey, and R. E. Waltz, Phys. Plasmas 14, 0055909 (2007); ibid. 15, 0055908 (2008)] tokamak transport model provides the linear mode frequency and growth rates to the kernel as well as the nonlinear spectral weight for each mode.

  5. Impact of micro-telluric lines on precise radial velocities and its correction

    NASA Astrophysics Data System (ADS)

    Cunha, D.; Santos, N. C.; Figueira, P.; Santerne, A.; Bertaux, J. L.; Lovis, C.

    2014-08-01

    Context. In the near future, new instruments such as ESPRESSO will arrive, allowing us to reach a precision in radial velocity measurements on the order of 10 cm s-1. At this level of precision, several noise sources that until now have been outweighed by photon noise will start to contribute significantly to the error budget. The telluric lines that are not neglected by the masks for the radial velocity computation, here called micro-telluric lines, are one such noise source. Aims: In this work we investigate the impact of micro-telluric lines in the radial velocities calculations. We also investigate how to correct the effect of these atmospheric lines on radial velocities. Methods: The work presented here follows two parallel lines. First, we calculated the impact of the micro-telluric lines by multiplying a synthetic solar-like stellar spectrum by synthetic atmospheric spectra and evaluated the effect created by the presence of the telluric lines. Then, we divided HARPS spectra by synthetic atmospheric spectra to correct for its presence on real data and calculated the radial velocity on the corrected spectra. When doing so, one considers two atmospheric models for the synthetic atmospheric spectra: the LBLRTM and TAPAS. Results: We find that the micro-telluric lines can induce an impact on the radial velocity calculation that can already be close to the current precision achieved with HARPS, and so its effect should not be neglected, especially for future instruments such as ESPRESSO. Moreover, we find that the micro-telluric lines' impact depends on factors, such as the radial velocity of the star, airmass, relative humidity, and the barycentric Earth radial velocity projected along the line of sight at the time of the observation. Appendix A is available in electronic form at http://www.aanda.org

  6. The M 4 Core Project with HST - IV. Internal kinematics from accurate radial velocities of 2771 cluster members★

    NASA Astrophysics Data System (ADS)

    Malavolta, L.; Piotto, G.; Bedin, L. R.; Sneden, C.; Nascimbeni, V.; Sommariva, V.

    2015-12-01

    We present a detailed study of the internal kinematics of the Galactic globular cluster M 4 (NGC 6121), by deriving the radial velocities from 7250 spectra for 2771 stars distributed from the upper part of the red giant branch down to the main sequence. We describe new approaches to determine the wavelength solution from day-time calibrations and to determine the radial velocity drifts that can occur between calibration and science observations when observing with the GIRAFFE spectrograph at Very Large Telescope. Two techniques to determine the radial velocity are compared, after a qualitative description of their advantages with respect to other commonly used algorithm, and a new approach to remove the sky contribution from the spectra obtained with fibre-fed spectrograph and further improve the radial velocity precision is presented. The average radial velocity of the cluster is = 71.08 ± 0.08 km s-1 with an average dispersion of μ _{v_c} = 3.97 km s-1. Using the same data set and the same statistical approach of previous analyses, 20 additional binary candidates are found, for a total of 87 candidates. A new determination of the internal radial velocity dispersion as a function of cluster distance is presented, resulting in a dispersion of 4.5 km s-1 within 2 arcmin from the centre of cluster and steadily decreasing outward. We statistically confirm the small amplitude of the cluster rotation, as suggested in the past by several authors. This new analysis represents a significant improvement with respect to previous results in literature and provides a fundamental observational input for the modelling of the cluster dynamics.

  7. Shear-velocity structure, radial anisotropy and dynamics of the Tibetan crust

    NASA Astrophysics Data System (ADS)

    Agius, Matthew R.; Lebedev, Sergei

    2014-12-01

    of radial anisotropy in the crust does not correlate with isotropic-average shear speed (and, by inference, with crustal rock viscosity) or with surface elevation. Instead, radial anisotropy is related to the deformation pattern and is the strongest in regions experiencing extension (crustal flattening), as noted previously. The growth of Tibet by the addition of Indian crustal rocks into its crust from the south is reflected in the higher crustal seismic velocities (and, thus, lower temperatures) in the southern compared to northern parts of the plateau (more recently added rocks having had less time to undergo radioactive heating within the thickened Tibetan crust). Gravity-driven flattening-the basic cause of extension and normal faulting in the southern, western and central Tibet-is evidenced by pervasive radial anisotropy in the middle crust beneath the regions undergoing extension; the overall eastward flow of the crust is directed by the boundaries and motions of the lithospheric blocks that surround Tibet.

  8. Origins of Solar Systems: Removing Activity-Related Radial Velocity Noise to Improve Extrasolar Planet Searches

    NASA Technical Reports Server (NTRS)

    Saar, Steven; Lindstrom, David (Technical Monitor)

    2003-01-01

    We have continued the super high resolution (R is approximately 200,000), high S/N (> 300) echelle study of joint line bisector and radial velocity variations using the McDonald 2-D coude. A long observing run in October 2002 was quite successful (8 clear nights). We now have close to three years of data, which begins to sample a good fraction of the magnetic cycle timescales for some of our targets (e.g., K Ceti; P(sub cyc)=5.6 yrs). This will be very helpful in unraveling the complex relationships between plage and v(sub r), changes which we have uncovered. A preliminary analysis of the limited data in hand, and find some tantalizing evidence for correlations between median line bisector displacement and radial velocity v(sub r). The correlation appears to be specific to the particular star being considered, probably since it is a function of both spectral type and rotation rate. Additional information regarding progress on the grant is included.

  9. Precise radial velocities of giant stars. IV. A correlation between surface gravity and radial velocity variation and a statistical investigation of companion properties

    NASA Astrophysics Data System (ADS)

    Hekker, S.; Snellen, I. A. G.; Aerts, C.; Quirrenbach, A.; Reffert, S.; Mitchell, D. S.

    2008-03-01

    Context: Since 1999, we have been conducting a radial velocity survey of 179 K giants using the Coudé Auxiliary Telescope at UCO/Lick observatory. At present ~20-100 measurements have been collected per star with a precision of 5 to 8 m s-1. Of the stars monitored, 145 (80%) show radial velocity (RV) variations at a level >20 m s-1, of which 43 exhibit significant periodicities. Aims: Our aim is to investigate possible mechanism(s) that cause these observed RV variations. We intend to test whether these variations are intrinsic in nature, or possibly induced by companions, or both. In addition, we aim to characterise the parameters of these companions. Methods: A relation between log g and the amplitude of the RV variations is investigated for all stars in the sample. Furthermore, the hypothesis that all periodic RV variations are caused by companions is investigated by comparing their inferred orbital statistics with the statistics of companions around main sequence F, G, and K dwarfs. Results: A strong relation is found between the amplitude of the RV variations and log g in K giant stars, as suggested earlier by Hatzes & Cochran (1998). However, most of the stars exhibiting periodic variations are located above this relation. These RV variations can be split in a periodic component which is not correlated with log g and a random residual part which does correlate with log g. Compared to main-sequence dwarf stars, K giants frequently exhibit periodic RV variations. Interpreting these RV variations as being caused by companions, the orbital parameters are different from the companions orbiting dwarfs. Conclusions: Intrinsic mechanisms play an important role in producing RV variations in K giants stars, as suggested by their dependence on log g. However, it appears that periodic RV variations are additional to these intrinsic variations, consistent with them being caused by companions. If indeed the majority of the periodic RV variations in K giants is interpreted

  10. VizieR Online Data Catalog: WOCS. LXVI. Radial velocity survey in M35 (Leiner+, 2015)

    NASA Astrophysics Data System (ADS)

    Leiner, E. M.; Mathieu, R. D.; Gosnell, N. M.; Geller, A. M.

    2015-09-01

    In this second paper (see also Geller et al. 2010, cat. J/AJ/139/1383) in a series studying the dynamical state of the young (150Myr) open cluster M35 we present an updated version of our complete radial velocity database for the cluster. Our sample is selected to cover the range of the M35 main sequence from 0.8 to 1.6Mȯ out to 30' from cluster center. In the 17 years that we have observed M35, we have gathered ~8000 moderate-precision (σi=0.5km/s) spectra of ~1300 stars. We find 418 of these to be confirmed radial velocity cluster members or likely members. Within our sample of 418 cluster members or likely members, we detect 64 velocity-variable stars. We present orbital solutions for 52 (see Tables 5 and 7) of these 64 systems, in addition to 28 (see Tables 6 and 8) completed orbital solutions for non-member binaries in our field of view. The binaries are drawn from a sample initially derived from the photometry of T. von Hippel taken at KPNO on the Burrell Schmidt telescope. Observations were taken on 1993 November 18-19, and include B and V photometry down to a magnitude of V=17 lying within a 70'*70' field of view. Subsequently, we updated this photometry for 74% of our sources with more precise BV photometry from C. P. Deliyannis (2006, private communication; Sarrazine et al., 2000AAS...197.4107S). This new photometry was taken on the WIYN 0.9m telescope with the S2KB imager and covers a 40'*40' field of view. See Geller et al. 2010 (cat. J/AJ/139/1383) for more information on these two sets of photometry. Beginning in 1997 September, we have obtained spectra for the stars in our sample at the WIYN 3.5m telescope at KPNO using the Hydra Multi-Object Spectrograph (MOS). For a detailed description of our observing and data reduction procedure see Geller et al. 2008 (cat. J/AJ/135/2264). In short, we typically use Hydra's blue sensitive fibers and an echelle grating providing a resolution of R~20000. These spectra are centered on 512.5nm, and span a ~25nm

  11. VizieR Online Data Catalog: WOCS. LXVI. Radial velocity survey in M35 (Leiner+, 2015)

    NASA Astrophysics Data System (ADS)

    Leiner, E. M.; Mathieu, R. D.; Gosnell, N. M.; Geller, A. M.

    2015-09-01

    In this second paper (see also Geller et al. 2010, cat. J/AJ/139/1383) in a series studying the dynamical state of the young (150Myr) open cluster M35 we present an updated version of our complete radial velocity database for the cluster. Our sample is selected to cover the range of the M35 main sequence from 0.8 to 1.6M⊙ out to 30' from cluster center. In the 17 years that we have observed M35, we have gathered ~8000 moderate-precision (σi=0.5km/s) spectra of ~1300 stars. We find 418 of these to be confirmed radial velocity cluster members or likely members. Within our sample of 418 cluster members or likely members, we detect 64 velocity-variable stars. We present orbital solutions for 52 (see Tables 5 and 7) of these 64 systems, in addition to 28 (see Tables 6 and 8) completed orbital solutions for non-member binaries in our field of view. The binaries are drawn from a sample initially derived from the photometry of T. von Hippel taken at KPNO on the Burrell Schmidt telescope. Observations were taken on 1993 November 18-19, and include B and V photometry down to a magnitude of V=17 lying within a 70'*70' field of view. Subsequently, we updated this photometry for 74% of our sources with more precise BV photometry from C. P. Deliyannis (2006, private communication; Sarrazine et al., 2000AAS...197.4107S). This new photometry was taken on the WIYN 0.9m telescope with the S2KB imager and covers a 40'*40' field of view. See Geller et al. 2010 (cat. J/AJ/139/1383) for more information on these two sets of photometry. Beginning in 1997 September, we have obtained spectra for the stars in our sample at the WIYN 3.5m telescope at KPNO using the Hydra Multi-Object Spectrograph (MOS). For a detailed description of our observing and data reduction procedure see Geller et al. 2008 (cat. J/AJ/135/2264). In short, we typically use Hydra's blue sensitive fibers and an echelle grating providing a resolution of R~20000. These spectra are centered on 512.5nm, and span a ~25nm

  12. Radial velocities of three poorly studied clusters and the kinematics of open clusters

    SciTech Connect

    Hayes, Christian R.; Friel, Eileen D. E-mail: efriel@indiana.edu

    2014-04-01

    We present radial velocities for stars in the field of the open star clusters Berkeley 44, Berkeley 81, and NGC 6802 from spectra obtained using the Wisconsin-Indiana-Yale-NOAO (WIYN) 3.5 m telescope. These clusters are of intermediate age (1-3 Gyr), located within the solar Galactocentric radius, and have no previous radial velocity measurements. We find mean radial velocities of –9.6 ± 3.0 km s{sup –1}, 48.1 ± 2.0 km s{sup –1}, and 12.4 ± 2.8 km s{sup –1} for Be 44, Be 81, and NGC 6802, respectively. We present an analysis of radial velocities of 134 open clusters of a wide range of ages using data obtained in this study and the literature. Assuming the system of clusters rotates about the Galactic center with a constant velocity, we find older clusters exhibit a slower rotation and larger line-of-sight (LOS) velocity dispersion than younger clusters. The gradual decrease in rotational velocity of the cluster system with age is accompanied by a smooth increase in LOS velocity dispersion, which we interpret as the effect of heating on the open cluster system over time.

  13. Transit and radial velocity survey efficiency comparison for a habitable zone Earth

    SciTech Connect

    Burke, Christopher J.

    2014-09-01

    Transit and radial velocity searches are two techniques for identifying nearby extrasolar planets to Earth that transit bright stars. Identifying a robust sample of these exoplanets around bright stars for detailed atmospheric characterization is a major observational undertaking. In this study we describe a framework that answers the question of whether a transit or radial velocity survey is more efficient at finding transiting exoplanets given the same amount of observing time. Within the framework we show that a transit survey's window function can be approximated using the hypergeometric probability distribution. We estimate the observing time required for a transit survey to find a transiting Earth-sized exoplanet in the habitable zone (HZ) with an emphasis on late-type stars. We also estimate the radial velocity precision necessary to detect the equivalent HZ Earth-mass exoplanet that also transits when using an equal amount of observing time as the transit survey. We find that a radial velocity survey with σ{sub rv} ∼ 0.6 m s{sup –1} precision has comparable efficiency in terms of observing time to a transit survey with the requisite photometric precision σ{sub phot} ∼ 300 ppm to find a transiting Earth-sized exoplanet in the HZ of late M dwarfs. For super-Earths, a σ{sub rv} ∼ 2.0 m s{sup –1} precision radial velocity survey has comparable efficiency to a transit survey with σ{sub phot} ∼ 2300 ppm.

  14. Radial velocity curves of ellipsoidal red giant binaries in the Large Magellanic Cloud

    SciTech Connect

    Nie, J. D.; Wood, P. R. E-mail: peter.wood@anu.edu.au

    2014-12-01

    Ellipsoidal red giant binaries are close binary systems where an unseen, relatively close companion distorts the red giant, leading to light variations as the red giant moves around its orbit. These binaries are likely to be the immediate evolutionary precursors of close binary planetary nebula and post-asymptotic giant branch and post-red giant branch stars. Due to the MACHO and OGLE photometric monitoring projects, the light variability nature of these ellipsoidal variables has been well studied. However, due to the lack of radial velocity curves, the nature of their masses, separations, and other orbital details has so far remained largely unknown. In order to improve this situation, we have carried out spectral monitoring observations of a large sample of 80 ellipsoidal variables in the Large Magellanic Cloud and we have derived radial velocity curves. At least 12 radial velocity points with good quality were obtained for most of the ellipsoidal variables. The radial velocity data are provided with this paper. Combining the photometric and radial velocity data, we present some statistical results related to the binary properties of these ellipsoidal variables.

  15. Orbital eccentricity of WASP-12 and WASP-14 from new radial velocity monitoring with SOPHIE

    NASA Astrophysics Data System (ADS)

    Husnoo, Nawal; Pont, Frédéric; Hébrard, Guillaume; Simpson, Elaine; Mazeh, Tsevi; Bouchy, François; Moutou, Claire; Arnold, Luc; Boisse, Isabelle; Díaz, Rodrigo F.; Eggenberger, Anne; Shporer, Avi

    2011-06-01

    As part of the long-term radial velocity monitoring of known transiting planets, we have acquired new radial velocity data for the two transiting systems WASP-12 and WASP-14, each harbouring a gas giant on a close orbit (orbital period of 1.09 and 2.24 d, respectively). In both cases, the initial orbital solution suggested a significant orbital eccentricity, 0.049 ± 0.015 for WASP-12b and 0.091 ± 0.003 for WASP-14b. Since then, measurements of the occultation of WASP-12 in the infrared have indicated that one projection of the eccentricity (e cos ω) was close to zero, casting doubt on the eccentricity from the initial radial velocity orbit. Our measurements show that the radial velocity data are compatible with a circular orbit. A MCMC analysis taking into account the presence of correlated systematic noise in both the radial velocity and photometric data gives e= 0.017+0.015-0.010. In contrast, we confirm the orbital eccentricity of WASP-14b, and refine its value to e= 0.0877 ± 0.0030, a 10σ detection. WASP-14b is thus the closest presently known planet with a confirmed eccentric orbit. Based on observations made at the 1.93-m telescopes at Observatoire de Haute-Provence (CNRS), France with the SOPHIE spectrograph.

  16. Long-term radial-velocity variations of the Sun as a star: The HARPS view

    NASA Astrophysics Data System (ADS)

    Lanza, A. F.; Molaro, P.; Monaco, L.; Haywood, R. D.

    2016-03-01

    Context. Stellar radial velocities play a fundamental role in the discovery of extrasolar planets and the measurement of their physical parameters as well as in the study of stellar physical properties. Aims: We investigate the impact of the solar activity on the radial velocity of the Sun using the HARPS spectrograph to obtain measurements that can be directly compared with those acquired in the extrasolar planet search programmes. Methods: We used the Moon, the Galilean satellites, and several asteroids as reflectors to measure the radial velocity of the Sun as a star and correlated this velocity with disc-integrated chromospheric and magnetic indexes of solar activity that are similar to stellar activity indexes. We discuss in detail the systematic effects that affect our measurements and the methods to account for them. Results: We find that the radial velocity of the Sun as a star is positively correlated with the level of its chromospheric activity at ~95 percent significance level. The amplitude of the long-term variation measured in the 2006-2014 period is 4.98 ± 1.44 m/s, which is in good agreement with model predictions. The standard deviation of the residuals obtained by subtracting a linear best fit is 2.82 m/s and is due to the rotation of the reflecting bodies and the intrinsic variability of the Sun on timescales shorter than the activity cycle. A correlation with a lower significance is detected between the radial velocity and the mean absolute value of the line-of-sight photospheric magnetic field flux density. Conclusions: Our results confirm similar correlations found in other late-type main-sequence stars and provide support to the predictions of radial velocity variations induced by stellar activity based on current models.

  17. RADIAL VELOCITIES FROM VLT-KMOS SPECTRA OF GIANT STARS IN THE GLOBULAR CLUSTER NGC 6388

    SciTech Connect

    Lapenna, E.; Mucciarelli, A.; Lanzoni, B.; Ferraro, F. R.; Dalessandro, E.; Valenti, E.; Cirasuolo, M.

    2015-01-01

    We present new radial velocity measurements for 82 stars, members of the Galactic globular cluster (GC) NGC 6388, obtained from ESO-VLT K-band Multi Object Spectrograph (KMOS) spectra acquired during the instrument Science Verification. The accuracy of the wavelength calibration is discussed and a number of tests of the KMOS response are presented. The cluster systemic velocity obtained (81.3 ± 1.5 km s{sup –1}) is in very good agreement with previous determinations. While a hint of ordered rotation is found between 9'' and 20'' from the cluster center, where the distribution of radial velocities is clearly bimodal, more data are needed before drawing any firm conclusions. The acquired sample of radial velocities has also been used to determine the cluster velocity dispersion (VD) profile between ∼9'' and 70'', supplementing previous measurements at r < 2'' and r > 60'' obtained with ESO-SINFONI and ESO-FLAMES spectroscopy, respectively. The new portion of the VD profile nicely matches the previous ones, better defining the knee of the distribution. The present work clearly shows the effectiveness of a deployable integral field unit in measuring the radial velocities of individual stars for determining the VD profile of Galactic GCs. It represents the pilot project for an ongoing large program with KMOS and FLAMES at the ESO-VLT, aimed at determining the next generation of VD and rotation profiles for a representative sample of GCs.

  18. Open Cluster Radial Velocity determination from observations at Observatório Pico Dos Dias

    NASA Astrophysics Data System (ADS)

    Faria, M. A. F.; Monteiro, H.; Dias, W. S.; Lépine, J. R. D.

    2014-10-01

    In studies of the dynamics of the Galactic disk, such as the determination of the speed of the spiral pattern and the permanence of stars in the spiral arms, it is crucial to know orbits obtained from proper motions, radial velocities and the potential of the Galaxy. Aiming to improve the statistics of our catalog of open clusters, maintained by our research group, we determined the radial velocity of stars belonging to a group of open clusters using spectra with a resolution of 4000, obtained at the Pico dos Dias Observatory (LNA) with the 1.60 m telescope and the Coudé spectrograph. We observed the open cluster's member stars and calculated their radial speeds using standard techniques. The stars were selected from our own database based on relevant information concerning the clusters, obtained by statistical analysis of their proper motions and/or their position in the HR's diagram. In this work, we present the detailed analysis of the data reduction and radial velocity determination using synthetic spectra from different libraries. Finally we present the open cluster's radial (and spacial) velocities.

  19. The OCCASO survey: presentation and radial velocities of 12 Milky Way open clusters

    NASA Astrophysics Data System (ADS)

    Casamiquela, L.; Carrera, R.; Jordi, C.; Balaguer-Núñez, L.; Pancino, E.; Hidalgo, S. L.; Martínez-Vázquez, C. E.; Murabito, S.; del Pino, A.; Aparicio, A.; Blanco-Cuaresma, S.; Gallart, C.

    2016-05-01

    Open clusters (OCs) are crucial for studying the formation and evolution of the Galactic disc. However, the lack of a large number of OCs analysed homogeneously hampers the investigations about chemical patterns and the existence of Galactocentric radial and vertical gradients, or an age-metallicity relation. To overcome this, we have designed the Open Cluster Chemical Abundances from Spanish Observatories (OCCASO) survey. We aim to provide homogeneous radial velocities, physical parameters and individual chemical abundances of six or more red clump stars for a sample of 25 old and intermediate-age OCs visible from the Northern hemisphere. To do so, we use high-resolution spectroscopic facilities (R ≥ 62 000) available at Spanish observatories. We present the motivation, design and current status of the survey, together with the first data release of radial velocities for 77 stars in 12 OCs, which represents about 50 per cent of the survey. We include clusters never studied with high-resolution spectroscopy before (NGC 1907, NGC 6991, NGC 7762), and clusters in common with other large spectroscopic surveys like the Gaia-ESO Survey (NGC 6705) and Apache Point Observatory Galactic Evolution Experiment (NGC 2682 and NGC 6819). We perform internal comparisons between instruments to evaluate and correct internal systematics of the results, and compare our radial velocities with previous determinations in the literature, when available. Finally, radial velocities for each cluster are used to perform a preliminary kinematic study in relation with the Galactic disc.

  20. Frequentist and Bayesian Orbital Parameter Estimaton from Radial Velocity Data Using RVLIN, BOOTTRAN, and RUN DMC

    NASA Astrophysics Data System (ADS)

    Nelson, Benjamin Earl; Wright, Jason Thomas; Wang, Sharon

    2015-08-01

    For this hack session, we will present three tools used in analyses of radial velocity exoplanet systems. RVLIN is a set of IDL routines used to quickly fit an arbitrary number of Keplerian curves to radial velocity data to find adequate parameter point estimates. BOOTTRAN is an IDL-based extension of RVLIN to provide orbital parameter uncertainties using bootstrap based on a Keplerian model. RUN DMC is a highly parallelized Markov chain Monte Carlo algorithm that employs an n-body model, primarily used for dynamically complex or poorly constrained exoplanet systems. We will compare the performance of these tools and their applications to various exoplanet systems.

  1. A demonstration device to simulate the radial velocity method for exoplanet detection

    NASA Astrophysics Data System (ADS)

    Choopan, W.; Liewrian, W.; Ketpichainarong, W.; Panijpan, B.

    2016-07-01

    A device for simulating exoplanet detection by the radial method based on the Doppler principle has been constructed. The spectral shift of light from a distant star, mutually revolving with the exoplanet, is simulated by the spectral shift of the sound wave emitted by the device’s star approaching and receding relative to the static frequency detector. The detected sound frequency shift reflects the relative velocity of the ‘star’ very well. Both teachers and students benefit from the radial velocity method and the transit method (published by us previously) provided by this device.

  2. VizieR Online Data Catalog: Coralie radial velocities for l Car (Anderson+, 2016)

    NASA Astrophysics Data System (ADS)

    Anderson, R. I.; Merand, A.; Kervella, P.; Breitfelder, J.; Lebouquin, J.-B.; Eyer, L.; Gallenne, A.; Palaversa, L.; Semaan, T.; Saesen, S.; Mowlavi, N.

    2016-07-01

    360 radial velocity measurements (RVs) of {ell} Carinae are made publicly available. These RVs were measured using optical spectra observed with the Coralie spectrograph mounted to the 1.2m Swiss Euler telescope situated at La Silla Observatory, Chile. (1 data file).

  3. VizieR Online Data Catalog: Radial velocity monitoring of 5 FGK stars (Endl+, 2016)

    NASA Astrophysics Data System (ADS)

    Endl, M.; Brugamyer, E. J.; Cochran, W. D.; MacQueen, P. J.; Robertson, P.; Meschiari, S.; Ramirez, I.; Shetrone, M.; Gullikson, K.; Johnson, M. C.; Wittenmyer, R.; Horner, J.; Ciardi, D. R.; Horch, E.; Simon, A. E.; Howell, S. B.; Everett, M.; Caldwell, C.; Castanheira, B. G.

    2016-04-01

    Our radial velocity (RV) measurements were obtained using the 2.7m Harlan J. Smith Telescope (HJST; R=60000, 3750-10200Å). For HD 95872, we also obtained 10 precise RV measurements using the 10m Keck I and its HIRES spectrograph (R=50000). (6 data files).

  4. VizieR Online Data Catalog: Bibliographic Catalogue of Radial Velocities (Barbier+ 1986)

    NASA Astrophysics Data System (ADS)

    Barbier-Brossat, M.; Petit, M.

    2015-09-01

    This compilation of stellar radial velocities is a continuation of Abt & Biggs (III/4). It includes 11000 references for galactic, large and small Magellanic stars published between 1970 and 1980. A description (in French) is available is the file "intro.txt". (2 data files).

  5. PlanetPack: Radial-velocity time-series analysis tool

    NASA Astrophysics Data System (ADS)

    Baluev, Roman V.

    2013-11-01

    PlanetPack facilitates and standardizes the advanced analysis of radial velocity (RV) data for the goal of exoplanets detection, characterization, and basic dynamical N-body simulations. PlanetPack is a command-line interpreter that can run either in an interactive mode or in a batch mode of automatic script interpretation.

  6. Daily variability of Ceres' albedo detected by means of radial velocities changes of the reflected sunlight

    NASA Astrophysics Data System (ADS)

    Molaro, P.; Lanza, A. F.; Monaco, L.; Tosi, F.; Lo Curto, G.; Fulle, M.; Pasquini, L.

    2016-05-01

    Bright features have been recently discovered by Dawn on Ceres, which extend previous photometric and Space Telescope observations. These features should produce distortions of the line profiles of the reflected solar spectrum and therefore an apparent radial velocity variation modulated by the rotation of the dwarf planet. Here we report on two sequences of observations of Ceres performed in the nights of 2015 July 31, August 26 and 27 by means of the high-precision High Accuracy Radial Velocity Planet Searcher (HARPS) spectrograph at the 3.6 m La Silla European Southern Observatory (ESO) telescope. The observations revealed a quite complex behaviour which likely combines a radial velocity modulation due to the rotation with an amplitude of ≈±6 m s-1 and an unexpected diurnal effect. The latter changes imply changes in the albedo of Occator's bright features due to the blaze produced by the exposure to solar radiation. The short-term variability of Ceres' albedo is on time-scales ranging from hours to months and can both be confirmed and followed by means of dedicated radial velocity observations.

  7. The first radial velocity measurements of a microlensing event: no evidence for the predicted binary⋆

    NASA Astrophysics Data System (ADS)

    Boisse, I.; Santerne, A.; Beaulieu, J.-P.; Fakhardji, W.; Santos, N. C.; Figueira, P.; Sousa, S. G.; Ranc, C.

    2015-10-01

    The gravitational microlensing technique allows the discovery of exoplanets around stars distributed in the disk of the galaxy towards the bulge. The alignment of two stars that led to the discovery is unique over the timescale of a human life, however, and cannot be re-observed. Moreover, the target host is often very faint and located in a crowded region. These difficulties hamper and often make impossible the follow up of the target and study of its possible companions. A radial-velocity curve was predicted for the binary system, OGLE-2011-BLG-0417, discovered and characterised from a microlensing event. We used the UVES spectrograph mounted at the VLT, ESO to derive precise radial-velocity measurements of OGLE-2011-BLG-0417. To gather high-precision radial velocities on faint targets of microlensing events, we proposed to use the source star as a reference to measure the lens radial velocities. We obtained ten radial velocities on the putative V = 18 lens with a dispersion of ~100 m s-1, spread over one year. Our measurements do not confirm the microlensing prediction for this binary system. The most likely scenario is that the putative V = 18 mag lens is actually a blend and not the primary lens which is 2 mag fainter. Further observations and analyses are needed to understand the microlensing observation and infer on the nature and characteristics of the lens itself. Based on observations made with ESO Telescope at the Paranal Observatory under program ID 092.C-0763(A) and 093.C-0532(A).Appendix A is available in electronic form at http://www.aanda.org

  8. Eclipsing binaries and fast rotators in the Kepler sample. Characterization via radial velocity analysis from Calar Alto

    NASA Astrophysics Data System (ADS)

    Lillo-Box, J.; Barrado, D.; Mancini, L.; Henning, Th.; Figueira, P.; Ciceri, S.; Santos, N.

    2015-04-01

    Context. The Kepler mission has searched for planetary transits in more than two hundred thousand stars by obtaining very accurate photometric data over a long period of time. Among the thousands of detected candidates, the planetary nature of around 15% has been established or validated by different techniques. But additional data are needed to characterize the rest of the candidates and reject other possible configurations. Aims: We started a follow-up program to validate, confirm, and characterize some of the planet candidates. In this paper we present the radial velocity analysis of those that present large variations, which are compatible with being eclipsing binaries. We also study those showing high rotational velocities, which prevents us from reaching the necessary precision to detect planetary-like objects. Methods: We present new radial velocity results for 13 Kepler objects of interest (KOIs) obtained with the CAFE spectrograph at the Calar Alto Observatory and analyze their high-spatial resolution (lucky) images obtained with AstraLux and the Kepler light curves of some interesting cases. Results: We have found five spectroscopic and eclipsing binaries (group A). Among them, the case of KOI-3853 is of particular interest. This system is a new example of the so-called heartbeat stars, showing dynamic tidal distortions in the Kepler light curve. We have also detected duration and depth variations of the eclipse. We suggest possible scenarios to explain such an effect, including the presence of a third substellar body possibly detected in our radial velocity analysis. We also provide upper mass limits to the transiting companions of six other KOIs with high rotational velocities (group B). This property prevents the radial velocity method from achieving the necessary precision to detect planetary-like masses. Finally, we analyze the large radial velocity variations of two other KOIs, which are incompatible with the presence of planetary-mass objects

  9. Radial velocities for the HIPPARCOS-Gaia Hundred-Thousand-Proper-Motion project

    NASA Astrophysics Data System (ADS)

    de Bruijne, J. H. J.; Eilers, A.-C.

    2012-10-01

    Context. The Hundred-Thousand-Proper-Motion (HTPM) project will determine the proper motions of ~113 500 stars using a ~23-year baseline. The proper motions will be based on space-based measurements exclusively, with the Hipparcos data, with epoch 1991.25, as first epoch and with the first intermediate-release Gaia astrometry, with epoch ~2014.5, as second epoch. The expected HTPM proper-motion standard errors are 30-190 μas yr-1, depending on stellar magnitude. Aims: Depending on the astrometric characteristics of an object, in particular its distance and velocity, its radial velocity can have a significant impact on the determination of its proper motion. The impact of this perspective acceleration is largest for fast-moving, nearby stars. Our goal is to determine, for each star in the Hipparcos catalogue, the radial-velocity standard error that is required to guarantee a negligible contribution of perspective acceleration to the HTPM proper-motion precision. Methods: We employ two evaluation criteria, both based on Monte-Carlo simulations, with which we determine which stars need to be spectroscopically (re-)measured. Both criteria take the Hipparcos measurement errors into account. The first criterion, the Gaussian criterion, is applicable to nearby stars. For distant stars, this criterion works but returns overly pessimistic results. We therefore use a second criterion, the robust criterion, which is equivalent to the Gaussian criterion for nearby stars but avoids biases for distant stars and/or objects without literature radial velocity. The robust criterion is hence our prefered choice for all stars, regardless of distance. Results: For each star in the Hipparcos catalogue, we determine the confidence level with which the available radial velocity and its standard error, taken from the XHIP compilation catalogue, are acceptable. We find that for 97 stars, the radial velocities available in the literature are insufficiently precise for a 68.27% confidence

  10. RADIAL VELOCITY ALONG THE VOYAGER 1 TRAJECTORY: THE EFFECT OF SOLAR CYCLE

    SciTech Connect

    Pogorelov, N. V.; Zank, G. P.; Borovikov, S. N.; Burlaga, L. F.; Decker, R. A.; Stone, E. C.

    2012-05-01

    As Voyager 1 and Voyager 2 are approaching the heliopause (HP)-the boundary between the solar wind (SW) and the local interstellar medium (LISM)-we expect new, unknown features of the heliospheric interface to be revealed. A seeming puzzle reported recently by Krimigis et al. concerns the unusually low, even negative, radial velocity components derived from the energetic ion distribution. Steady-state plasma models of the inner heliosheath (IHS) show that the radial velocity should not be equal to zero even at the surface of the HP. Here we demonstrate that the velocity distributions observed by Voyager 1 are consistent with time-dependent simulations of the SW-LISM interaction. In this Letter, we analyze the results from a numerical model of the large-scale heliosphere that includes solar cycle effects. Our simulations show that prolonged periods of low to negative radial velocity can exist in the IHS at substantial distances from the HP. It is also shown that Voyager 1 was more likely to observe such regions than Voyager 2.

  11. Origins of Solar Systems: Removing Activity-Related Radial Velocity Noise To Improve Extrasolar Planet Searches

    NASA Technical Reports Server (NTRS)

    Saar, Steven

    2002-01-01

    We have continued the super high resolution (R is approximately 200,000), high S/N ((greater than) 300) echelle study of joint line bisector and radial velocity variations using the McDonald 2-D (two dimensional) coude. Observing runs in October 2000 and March 2001 were plagued by poor weather, but runs in June and October 2001 were good. We have made a preliminary analysis of the limited data in hand, and find some tantalizing evidence for correlations between median line bisector displacement and radial velocity v (sub r). The correlation appears to be specific to the particular star being considered, probably since it is a function of both spectral type and rotation rate.

  12. A velocity-dependent anomalous radial transport model for (2-D, 2-V) kinetic transport codes

    NASA Astrophysics Data System (ADS)

    Bodi, Kowsik; Krasheninnikov, Sergei; Cohen, Ron; Rognlien, Tom

    2008-11-01

    Plasma turbulence constitutes a significant part of radial plasma transport in magnetically confined plasmas. This turbulent transport is modeled in the form of anomalous convection and diffusion coefficients in fluid transport codes. There is a need to model the same in continuum kinetic edge codes [such as the (2-D, 2-V) transport version of TEMPEST, NEO, and the code being developed by the Edge Simulation Laboratory] with non-Maxwellian distributions. We present an anomalous transport model with velocity-dependent convection and diffusion coefficients leading to a diagonal transport matrix similar to that used in contemporary fluid transport models (e.g., UEDGE). Also presented are results of simulations corresponding to radial transport due to long-wavelength ExB turbulence using a velocity-independent diffusion coefficient. A BGK collision model is used to enable comparison with fluid transport codes.

  13. VizieR Online Data Catalog: Radial velocity curves of LMC ellipsoidal variables (Nie+, 2014)

    NASA Astrophysics Data System (ADS)

    Nie, J. D.; Wood, P. R.

    2014-11-01

    We initially selected 86 sequence E candidates from those given in Soszynski et al. 2004 (cat. J/AcA/54/347). The radial velocity observations were taken using the Wide Field Spectrograph (WiFeS) mounted on the Australian National University 2.3m telescope at Siding Spring Observatory. WiFes has six gratings. For our observations, the gratings B7000 (wavelength coverage of 4184-5580Å) and I7000 (wavelength coverage of 6832-9120Å) were chosen for the blue and red CCD, respectively. These two gratings give a two-pixel resolution R=7000. We carried out 18 weeks of radial velocity monitoring, from 2010 September to 2012 March. (2 data files).

  14. VizieR Online Data Catalog: Radial velocity and photometry in NGC 4372 (Kacharov+, 2014)

    NASA Astrophysics Data System (ADS)

    Kacharov, N.; Bianchini, P.; Koch, A.; Frank, M. J.; Martin, N. F.; van de Ven, G.; Puzia, T. H.; McDonald, I.; Johnson, C. I.; Zijlstra, A. A.

    2014-06-01

    We present the radial velocities of 220 stars in the field of the globular cluster NGC 4372 measured from high resolution FLAMES/GIRAFFE spectra. We have confirm 131 cluster member stars from radial velocity and metallicity constraints. The rest are foreground contaminants. We also present a BVI photometric catalogue in a field of view covering 30x30arcmin, centred on NGC 4372. We used archival imaging obtained with the Wide Field Imager (WFI) at the 2.2m MPG/ESO telescope at La Silla. We used the 2MASS point source catalog as astrometric reference. Photometric zero points were fixed to standard stars in the same field from the standard star database of Stetson (2000PASP..112..925S, 2005PASP..117..563S). We have estimated individual reddening for each star in the catalogue. (2 data files).

  15. CARMENES: A New Visible/Near-IR Radial-Velocity Spectrograph

    NASA Astrophysics Data System (ADS)

    Quirrenbach, Andreas; Carmenes Consortium

    2016-07-01

    CARMENES is a next-generation radial-velocity instrument that has been constructed for the 3.5m telescope at the Calar Alto Observatory by a consortium of eleven Spanish and German institutions. It consists of two separate échelle spectrographs covering the wavelength range from 0.55 to 1.7μm at a spectral resolution of R = 82,000, fed by fibers from the Cassegrain focus of the telescope. CARMENES saw "First Light" on Nov 9, 2015. We report on results from the commissioning and the first months of operation, and discuss the plans for the large M dwarf survey that is the core science program of CARMENES. With a bit of luck, CARMENES may find a few planets that are very well suited for characterization by JWST. In the longer run, CARMENES will be an excellent instrument for radial-velocity follow-up of transit survey missions such as TESS and PLATO.

  16. VizieR Online Data Catalog: Radial velocities of HD 6434 (Hinkel+, 2015)

    NASA Astrophysics Data System (ADS)

    Hinkel, N. R.; Kane, S. R.; Pilyavsky, G.; Boyajian, T. S.; James, D. J.; Naef, D.; Fischer, D. A.; Udry, S.

    2016-04-01

    Previous radial velocity observations of HD6434 (Mayor et al. 2004, cat. J/A+A/415/391) were undertaken with the CORALIE spectrometer mounted on the 1.2m Euler Swiss telescope at La Silla. Those observations were conducted as part of the CORALIE exoplanet search program (Udry et al. 2000, cat. J/A+A/356/590). We continued to monitor HD6434 using CORALIE to improve the Keplerian orbital solution and provide an accurate transit ephemeris. The complete data set of 137 measurements is shown in Table2 including previously acquired measurements and 59 new measurements. These new measurements extend the overall time baseline for the radial velocity observations by a factor of ~3.6, for a total baseline of ~15 years. (1 data file).

  17. TOWARD UNDERSTANDING STELLAR RADIAL VELOCITY JITTER AS A FUNCTION OF WAVELENGTH: THE SUN AS A PROXY

    SciTech Connect

    Marchwinski, Robert C.; Mahadevan, Suvrath; Robertson, Paul; Ramsey, Lawrence; Harder, Jerald E-mail: suvrath@astro.psu.edu E-mail: lwr@psu.edu

    2015-01-01

    Using solar spectral irradiance measurements from the SORCE spacecraft and the F/F' technique, we have estimated the radial velocity (RV) scatter induced on the Sun by stellar activity as a function of wavelength. Our goal was to evaluate the potential advantages of using new near-infrared (NIR) spectrographs to search for low-mass planets around bright F, G, and K stars by beating down activity effects. Unlike M dwarfs, which have higher fluxes and therefore greater RV information content in the NIR, solar-type stars are brightest at visible wavelengths, and, based solely on information content, are better suited to traditional optical RV surveys. However, we find that the F/F' estimated RV noise induced by stellar activity is diminished by up to a factor of four in the NIR versus the visible. Observations with the upcoming future generation of NIR instruments can be a valuable addition to the search for low-mass planets around bright FGK stars in reducing the amount of stellar noise affecting RV measurements.

  18. Radial-velocity measures and the existence of astrophysical binaries in late-type dwarf stars

    NASA Technical Reports Server (NTRS)

    Bopp, B. W.; Meredith, R.

    1986-01-01

    Radial velocities with errors of 1-2 km/s are presented based on CCD scans obtained with the Kitt Peak National Observatory coude feed telescope between 1982 and 1985 of 48 dK-M stars that lack Balmer emission. Comparison with Gliese's (1969) values shows only two stars to be spectroscopic binary candidates with small velocity amplitudes. No evidence for any short period (less than 10 days) binaries is found, supporting the conclusions of Young et al. (1986) that there are no astrophysical binaries among these chromosherically inactive dM stars.

  19. VizieR Online Data Catalog: HU Vir radial velocities and VI light curves (Harutyunyan+, 2016)

    NASA Astrophysics Data System (ADS)

    Harutyunyan, G.; Strassmeier, K. G.; Kuenstler, A.; Carroll, T. A.; Weber, M.

    2016-07-01

    We present two tables with the new STELLA radial velocity data set and the APT Johnson-Cousins V and I photometric data set for HU Virginis. RVs from STELLA-SES spectra were derived from an order-by-order cross correlation with a synthetic template spectrum and then averaged. The photometric measurements were always made differentially with respect to HD 106270 and HD 106332 as a comparison and check star, respectively. (2 data files).

  20. Line-profile variations in radial-velocity measurements. Two alternative indicators for planetary searches

    NASA Astrophysics Data System (ADS)

    Figueira, P.; Santos, N. C.; Pepe, F.; Lovis, C.; Nardetto, N.

    2013-09-01

    Aims: We introduce two methods to identify false-positive planetary signals in the context of radial-velocity exoplanet searches. The first is the bi-Gaussian cross-correlation function fitting (and monitoring of the parameters derived from it), and the second is the measurement of asymmetry in radial-velocity spectral line information content, Vasy. We assess the usefulness of each of these methods by comparing their results with those delivered by current indicators. Methods: We make a systematic analysis of the most used common line profile diagnosis, Bisector Inverse Slope and Velocity Span, along with the two proposed ones. We evaluate all these diagnosis methods following a set of well-defined common criteria and using both simulated and real data. We apply them to simulated cross-correlation functions that are created with the program SOAP and which are affected by the presence of stellar spots. We consider different spot properties on stars with different rotation profiles and simulate observations as obtained with high-resolution spectrographs. We then apply our methodology to real cross-correlation functions, which are computed from HARPS spectra, for stars with a signal originating in activity (thus spots) and for those with a signal rooted on a planet. Results: We demonstrate that the bi-Gaussian method allows a more precise characterization of the deformation of line profiles than the standard bisector inverse slope. The calculation of the deformation indicator is simpler and its interpretation more straightforward. More importantly, its amplitude can be up to 30% larger than that of the bisector span, allowing the detection of smaller-amplitude correlations with radial-velocity variations. However, a particular parametrization of the bisector inverse slope is shown to be more efficient on high-signal-to-noise data than both the standard bisector and the bi-Gaussian. The results of the Vasy method show that this indicator is more effective than any of

  1. AN AFFINE-INVARIANT SAMPLER FOR EXOPLANET FITTING AND DISCOVERY IN RADIAL VELOCITY DATA

    SciTech Connect

    Hou Fengji; Hogg, David W.; Goodman, Jonathan; Weare, Jonathan; Schwab, Christian

    2012-02-01

    Markov chain Monte Carlo (MCMC) proves to be powerful for Bayesian inference and in particular for exoplanet radial velocity fitting because MCMC provides more statistical information and makes better use of data than common approaches like chi-square fitting. However, the nonlinear density functions encountered in these problems can make MCMC time-consuming. In this paper, we apply an ensemble sampler respecting affine invariance to orbital parameter extraction from radial velocity data. This new sampler has only one free parameter, and does not require much tuning for good performance, which is important for automatization. The autocorrelation time of this sampler is approximately the same for all parameters and far smaller than Metropolis-Hastings, which means it requires many fewer function calls to produce the same number of independent samples. The affine-invariant sampler speeds up MCMC by hundreds of times compared with Metropolis-Hastings in the same computing situation. This novel sampler would be ideal for projects involving large data sets such as statistical investigations of planet distribution. The biggest obstacle to ensemble samplers is the existence of multiple local optima; we present a clustering technique to deal with local optima by clustering based on the likelihood of the walkers in the ensemble. We demonstrate the effectiveness of the sampler on real radial velocity data.

  2. An Affine-invariant Sampler for Exoplanet Fitting and Discovery in Radial Velocity Data

    NASA Astrophysics Data System (ADS)

    Hou, Fengji; Goodman, Jonathan; Hogg, David W.; Weare, Jonathan; Schwab, Christian

    2012-02-01

    Markov chain Monte Carlo (MCMC) proves to be powerful for Bayesian inference and in particular for exoplanet radial velocity fitting because MCMC provides more statistical information and makes better use of data than common approaches like chi-square fitting. However, the nonlinear density functions encountered in these problems can make MCMC time-consuming. In this paper, we apply an ensemble sampler respecting affine invariance to orbital parameter extraction from radial velocity data. This new sampler has only one free parameter, and does not require much tuning for good performance, which is important for automatization. The autocorrelation time of this sampler is approximately the same for all parameters and far smaller than Metropolis-Hastings, which means it requires many fewer function calls to produce the same number of independent samples. The affine-invariant sampler speeds up MCMC by hundreds of times compared with Metropolis-Hastings in the same computing situation. This novel sampler would be ideal for projects involving large data sets such as statistical investigations of planet distribution. The biggest obstacle to ensemble samplers is the existence of multiple local optima; we present a clustering technique to deal with local optima by clustering based on the likelihood of the walkers in the ensemble. We demonstrate the effectiveness of the sampler on real radial velocity data.

  3. Removing Activity-Related Radial Velocity Noise to Improve Extrasolar Planet Searches

    NASA Technical Reports Server (NTRS)

    Saar, Steven; Lindstrom, David M. (Technical Monitor)

    2004-01-01

    We have made significant progress towards the proposal goals of understanding the causes and effects of magnetic activity-induced radial velocity (v_r) jitter and developing methods for correcting it. In the process, we have also made some significant discoveries in the fields of planet-induced stellar activity, planet detection methods, M dwarf convection, starspot properties, and magnetic dynamo cycles. We have obtained super high resolution (R approximately 200,000), high S / N (greater than 300) echelle study of joint line bisector and radial velocity variations using the McDonald 2-D coude. A long observing run in October 2002 in particular was quite successful (8 clear nights). We now have close to three years of data, which begins to sample a good fraction of the magnetic cycle timescales for some of our targets (e.g., kappa Ceti; P_cyc = 5.6 yrs). This will be very helpful in unraveling the complex relationships between plage and radial velocity (v-r) changes which we have uncovered. Preliminary analysis (Saar et al. 2003) of the data in hand, reveals correlations between median line bisector displacement and v_r. The correlation appears to be specific the the particular star being considered, probably since it is a function of both spectral type and rotation rate. Further analysis and interpretation will be in the context of evolving plage models and is in progress.

  4. The rotation of the halo of NGC 6822 from the radial velocities of carbon stars

    NASA Astrophysics Data System (ADS)

    Thompson, Graham P.; Ryan, Sean G.; Sibbons, Lisette F.

    2016-11-01

    Using spectra taken with the AAOmega spectrograph, we measure the radial velocities of over 100 stars, many of which are intermediate age carbon stars, in the direction of the dwarf irregular galaxy NGC 6822. Kinematic analysis suggests that the carbon stars in the sample are associated with NGC 6822, and estimates of its radial velocity and galactic rotation are made from a star-by-star analysis of its carbon star population. We calculate a heliocentric radial velocity for NGC 6822 of -51 ± 3 km s-1 and show that the population rotates with a mean rotation speed of 11.2 ± 2.1 km s-1 at a mean distance of 1.1 kpc from the galactic centre, about a rotation axis with a position angle of 26° ± 13°, as projected on the sky. This is close to the rotation axis of the H I gas disc and suggests that NGC 6822 is not a polar ring galaxy, but is dynamically closer to a late-type galaxy. However, the rotation axis is not aligned with the minor axis of the AGB isodensity profiles and this remains a mystery.

  5. Miniature Exoplanet Radial Velocity Array (MINERVA) I. Design, Commissioning, and First Science Results

    NASA Astrophysics Data System (ADS)

    Swift, Jonathan J.; Bottom, Michael; Johnson, John A.; Wright, Jason T.; McCrady, Nate; Wittenmyer, Robert A.; Plavchan, Peter; Riddle, Reed; Muirhead, Philip S.; Herzig, Erich; Myles, Justin; Blake, Cullen H.; Eastman, Jason; Beatty, Thomas G.; Barnes, Stuart I.; Gibson, Steven R.; Lin, Brian; Zhao, Ming; Gardner, Paul; Falco, Emilio; Criswell, Stephen; Nava, Chantanelle; Robinson, Connor; Sliski, David H.; Hedrick, Richard; Ivarsen, Kevin; Hjelstrom, Annie; de Vera, Jon; Szentgyorgyi, Andrew

    2015-04-01

    The Miniature Exoplanet Radial Velocity Array (MINERVA) is a U.S.-based observational facility dedicated to the discovery and characterization of exoplanets around a nearby sample of bright stars. MINERVA employs a robotic array of four 0.7-m telescopes outfitted for both high-resolution spectroscopy and photometry, and is designed for completely autonomous operation. The primary science program is a dedicated radial velocity survey and the secondary science objective is to obtain high-precision transit light curves. The modular design of the facility and the flexibility of our hardware allows for both science programs to be pursued simultaneously, while the robotic control software provides a robust and efficient means to carry out nightly observations. We describe the design of MINERVA, including major hardware components, software, and science goals. The telescopes and photometry cameras are characterized at our test facility on the Caltech campus in Pasadena, California, and their on-sky performance is validated. The design and simulated performance of the spectrograph is briefly discussed as we await its completion. New observations from our test facility demonstrate sub-mmag photometric precision of one of our radial velocity survey targets, and we present new transit observations and fits of WASP-52b-a known hot-Jupiter with an inflated radius and misaligned orbit. The process of relocating the MINERVA hardware to its final destination at the Fred Lawrence Whipple Observatory in southern Arizona has begun, and science operations are expected to commence in 2015.

  6. Radial Velocities, Binarity, and Kinematic Membership in the Open Cluster NGC 2516

    NASA Astrophysics Data System (ADS)

    González, Jorge Federico; Lapasset, Emilio

    2000-05-01

    We present echelle spectroscopic observations for 36 bright (V<9.6) stars in the open cluster NGC 2516, including several blue straggler candidates and four red giants. Radial velocities are derived by cross-correlations using high signal-to-noise ratio standard spectra as templates. From 22 cluster members a mean cluster velocity of +22.0+/-0.2 km s-1 was derived. Membership probabilities of the observed stars are computed on the basis of their distance to the cluster center and kinematic criteria. We report the discovery of three double-lined spectroscopic binaries and several probable binaries among main-sequence stars. A binary frequency of more than 26% is found among the high-mass main-sequence stars. The blue straggler HD 66341 is a slowly rotating cluster member with constant velocity, while HD 66194 is a fast-rotating Be star with probable variations in radial velocity. Other blue straggler candidates, such as HD 65663, 65950, 66066, and 65987, must be considered turnoff stars. The observations presented here were obtained at the Complejo Astronómico El Leoncito (CASLEO), which is operated under agreement between the Consejo Nacional de Investigaciones Científicas y Técnicas de la República Argentina (CONICET) and the national universities of La Plata, Córdoba, and San Juan.

  7. Radial velocities of stars in the globular cluster M4 and the cluster distance

    NASA Technical Reports Server (NTRS)

    Peterson, R. C.; Rees, Richard F.; Cudworth, Kyle M.

    1995-01-01

    The internal stellar velocity distribution of the globular cluster M4 is evaluated from nearly 200 new radial velocity measurements good to 1 km/s and a rederivation of existing proper motions. The mean radial velocity of the cluster is 70.9 +/- 0.6 km/s. The velocity dispersion is 3.5 +/- 0.3 km/s at the core, dropping marginally towards the outskirts. Such a low internal dispersion is somewhat at odds with the cluster's orbit, for which the perigalacticon is sufficiently close to the galactic center that the probability of cluster disruption is high; a tidal radius two-thirds the currently accepted value would eliminate the discrepancy. The cluster mass-to-light ratio is also small, M/L(sub V) = 1.0 +/- 0.4 in solar units. M4 thus joins M22 as a cluster of moderate and concentration with a mass-to-light ratio among the lowest known. The astrometric distance to the cluster is also smaller than expected, 1.72 +/- 0.14 kpc. This is only consistent with conventional estimates of the luminosity of horizontal branch stars provided an extinction law R = A(sub V)/E(B-V) approximately 4 is adopted, as has been suggested recently by several authors.

  8. The first high-precision radial velocity search for extra-solar planets

    NASA Astrophysics Data System (ADS)

    Walker, Gordon A. H.

    2012-01-01

    The reflex motion of a star induced by a planetary companion is too small to detect by photographic astrometry. The apparent discovery in the 1960s of planetary systems around certain nearby stars, in particular Barnard's star, turned out to be spurious. Conventional stellar radial velocities determined from photographic spectra at that time were also too inaccurate to detect the expected reflex velocity changes. In the late 1970s and early 1980s, the introduction of solid-state, signal-generating detectors and absorption cells to impose wavelength fiducials directly on the starlight, reduced radial velocity errors to the point where such a search became feasible. Beginning in 1980, our team from UBC introduced an absorption cell of hydrogen fluoride gas in front of the CFHT coudé spectrograph and, for 12 years, monitored the radial velocities of some 29 solar-type stars. Since it was assumed that extra-solar planets would most likely resemble Jupiter in mass and orbit, we were awarded only three or four two-night observing runs each year. Our survey highlighted three potential planet hosting stars, γ Cep (K1 IV), β Gem (K0 III), and ɛ Eri (K2 V). The putative planets all resembled Jovian systems with periods and masses of: 2.5 years and 1.4 MJ, 1.6 years and 2.6 MJ, and 6.9 years and 0.9 MJ, respectively. All three were subsequently confirmed from more extensive data by the Texas group led by Cochran and Hatzes who also derived the currently accepted orbital elements. None of these three systems is simple. All five giant stars and the supergiant in our survey proved to be intrinsic velocity variables. When we first drew attention to a possible planetary companion to γ Cep in 1988 it was classified as a giant, and there was the possibility that its radial velocity variations and those of β Gem (K0 III) were intrinsic to the stars. A further complication for γ Cep was the presence of an unseen secondary star in an orbit with a period initially estimated at

  9. Radial velocity studies and absolute parameters of contact binaries. I - AB Andromedae

    NASA Technical Reports Server (NTRS)

    Hrivnak, Bruce J.

    1988-01-01

    New radial velocity curves have been obtained for the contact binary AB And, using the cross-correlation technique. A mass ratio of 0.479 is determined, which is revised to 0.491 when the velocities are corrected for proximity effects using a light curve model. These values differ by less than ten percent from the photometric mass ratio. An analysis of the symmetric B and V light curves reported by Rigterink in 1973 using the spectroscopic mass ratio yields a consistent set of light and velocity curve elements. These also produce a reasonably good fit to the infrared J and K light curves reported by Jameson and Akinci in 1979. Absolute elements are determined, and these indicate that both components have a main-sequence internal structure. These absolute parameters, together with the Galactic kinematics, suggest an age for the system similar to or greater than that of the Sun.

  10. VizieR Online Data Catalog: Radial velocities of 7 cataclysmic binaries (Halpern+, 2015)

    NASA Astrophysics Data System (ADS)

    Halpern, J. P.; Thorstensen, J. R.

    2016-04-01

    Our instrumentation, and reduction and analysis procedures are essentially identical to those described in Paper I (Thorstensen et al. 2013, cat. J/AJ/146/107). All of our optical data are from the MDM Observatory (http://mdm.kpno.noao.edu/index/Instrumentation.html), which comprises the 1.3m McGraw-Hill telescope and the 2.4m Hiltner telescope, both on the southwest ridge of Kitt Peak, Arizona. With a single exception, the radial velocity studies to search for the orbital periods were done on the 2.4m, while high-cadence photometry sensitive to spin periods was carried out on the 1.3m. All of our radial velocity studies used the modular spectrograph, as described in Paper I (Thorstensen et al. 2013, cat. J/AJ/146/107). Most of our velocities are from the the 2.4m telescope. Some spectra of Swift J2124.6+0500, and all the data we used for Swift J0939.7-3224, are from the McGraw-Hill 1.3m telescope, again with the modular spectrograph. For four newly identified objects we have only single spectra that were obtained on two observing runs on the 2.4m. These used the Boller and Chivens CCD spectrograph (CCDS) and the Ohio State Multi-Object Spectrograph (OSMOS). Descriptions of these instruments can be found on the MDM Observatory web page (http://mdm.kpno.noao.edu/index/Instrumentation.html). The objects observed are listed in Table1. Table2 lists the radial velocity data, and Table3 gives parameters of the best-fit sinusoids. (3 data files).

  11. [The radial velocity measurement accuracy of different spectral type low resolution stellar spectra at different signal-to-noise ratio].

    PubMed

    Wang, Feng-Fei; Luo, A-Li; Zhao, Yong-Heng

    2014-02-01

    The radial velocity of the star is very important for the study of the dynamics structure and chemistry evolution of the Milky Way, is also an useful tool for looking for variable or special objects. In the present work, we focus on calculating the radial velocity of different spectral types of low-resolution stellar spectra by adopting a template matching method, so as to provide effective and reliable reference to the different aspects of scientific research We choose high signal-to-noise ratio (SNR) spectra of different spectral type stellar from the Sloan Digital Sky Survey (SDSS), and add different noise to simulate the stellar spectra with different SNR. Then we obtain theradial velocity measurement accuracy of different spectral type stellar spectra at different SNR by employing a template matching method. Meanwhile, the radial velocity measurement accuracy of white dwarf stars is analyzed as well. We concluded that the accuracy of radial velocity measurements of early-type stars is much higher than late-type ones. For example, the 1-sigma standard error of radial velocity measurements of A-type stars is 5-8 times as large as K-type and M-type stars. We discuss the reason and suggest that the very narrow lines of late-type stars ensure the accuracy of measurement of radial velocities, while the early-type stars with very wide Balmer lines, such as A-type stars, become sensitive to noise and obtain low accuracy of radial velocities. For the spectra of white dwarfs stars, the standard error of radial velocity measurement could be over 50 km x s(-1) because of their extremely wide Balmer lines. The above conclusion will provide a good reference for stellar scientific study. PMID:24822441

  12. [The radial velocity measurement accuracy of different spectral type low resolution stellar spectra at different signal-to-noise ratio].

    PubMed

    Wang, Feng-Fei; Luo, A-Li; Zhao, Yong-Heng

    2014-02-01

    The radial velocity of the star is very important for the study of the dynamics structure and chemistry evolution of the Milky Way, is also an useful tool for looking for variable or special objects. In the present work, we focus on calculating the radial velocity of different spectral types of low-resolution stellar spectra by adopting a template matching method, so as to provide effective and reliable reference to the different aspects of scientific research We choose high signal-to-noise ratio (SNR) spectra of different spectral type stellar from the Sloan Digital Sky Survey (SDSS), and add different noise to simulate the stellar spectra with different SNR. Then we obtain theradial velocity measurement accuracy of different spectral type stellar spectra at different SNR by employing a template matching method. Meanwhile, the radial velocity measurement accuracy of white dwarf stars is analyzed as well. We concluded that the accuracy of radial velocity measurements of early-type stars is much higher than late-type ones. For example, the 1-sigma standard error of radial velocity measurements of A-type stars is 5-8 times as large as K-type and M-type stars. We discuss the reason and suggest that the very narrow lines of late-type stars ensure the accuracy of measurement of radial velocities, while the early-type stars with very wide Balmer lines, such as A-type stars, become sensitive to noise and obtain low accuracy of radial velocities. For the spectra of white dwarfs stars, the standard error of radial velocity measurement could be over 50 km x s(-1) because of their extremely wide Balmer lines. The above conclusion will provide a good reference for stellar scientific study.

  13. VizieR Online Data Catalog: Aldebaran radial velocity variations (Hatzes+, 2015)

    NASA Astrophysics Data System (ADS)

    Hatzes, A. P.; Cochran, W. D.; Endl, M.; Guenther, E. W.; MacQueen, P.; Hartmann, M.; Zechmeister, M.; Han, I.; Lee, B.-C.; Walker, G. A. H.; Yang, S.; Larson, A. M.; Kim, K.-M.; Mkrtichian, D. E.; Dollinger, M.; Simon, A. E.; Girardi, L.

    2015-07-01

    Seven independent data sets of high precision radial velocity data were used for our analysis. Precise RV measurements were also made with a Hydrogen-Fluoride (H-F) cell as part of the CFHT survey (hereafter the "CFHT" data set) of Walker et al. (1989ApJ...343L..21W) as well as additional measurements from the Dominion Astrophysical Observatory (hereafter "DAO" data set) using the same technique. See Campbell & Walker (1979PASP...91..540C) and Larson et al. (1993PASP..105..825L) for a description of the H-F measurements. For the remaining five RV data sets an iodine (I2) cell provided the wave- length reference. These include the original measurements using the McDonald Observatory 2.1m telescope (here-after "McD-2.1m" data set) and the coude spectrograph in the so-called "cs11" focus (hereafter "McD-CS11" data set) of the 2.7m telescope at McDonald Observatory. We should note that the we did not include the McDonald data that were used for the bisector measurements of Hatzes & Cochran (1998MNRAS.293..469H). These were taken using telluric lines as a wavelength reference which had a lower precision than the iodine wavelength calibration or H-F methods. The latest McDonald measurements were taken using the Tull Spectrograph at the so-called "cs23" focus (here-after the "McD-Tull" data set) as part of a long-term planet search program (e.g. Cochran et al., 1997ApJ...483..457C; Endl et al., 2004ApJ...611.1121E; Robertson et al., 2012ApJ...749...39R). (7 data files).

  14. Hide and Seek: Radial-Velocity Searches for Planets around Active Stars

    NASA Astrophysics Data System (ADS)

    Haywood, Raphaëlle Dawn

    2015-11-01

    The detection of low-mass extra-solar planets through radial-velocity searches is currently limited by the intrinsic magnetic activity of the host stars. The correlated noise that arises from their natural radial-velocity variability can easily mimic or conceal the orbital signals of super-Earth and Earth-mass extra-solar planets. I developed an intuitive and robust data analysis framework in which the activity-induced variations are modelled with a Gaussian process that has the frequency structure of the photometric variations of the star, thus allowing me to determine precise and reliable planetary masses. I applied this technique to three recently discovered planetary systems: CoRoT-7, Kepler-78 and Kepler-10. I determined the masses of the transiting super-Earth CoRoT-7b and the small Neptune CoRoT-7c to be 4.73 ± 0.95 M⊕ and 13.56 ± 1.08 M⊕, respectively. The density of CoRoT-7b is 6.61 ± 1.72 g.cm-3, which is compatible with a rocky composition. I carried out Bayesian model selection to assess the nature of a previously identified signal at 9 days, and found that it is best interpreted as stellar activity. Despite the high levels of activity of its host star, I determined the mass of the Earth-sized planet Kepler-78b to be 1.76 ± 0.18 M⊕. With a density of 6.2(+1.8:-1.4) g.cm-3, it is also a rocky planet. I found the masses of Kepler-10b and Kepler-10c to be 3.31 ± 0.32 M⊕ and 16.25 ± 3.66 M⊕, respectively. Their densities, of 6.4(+1.1:-0.7) g.cm-3 and 8.1 ± 1.8 g.cm-3, imply that they are both of rocky composition - even the 2 Earth-radius planet Kepler-10c! In parallel, I deepened our understanding of the physical origin of stellar radial-velocity variability through the study of the Sun, which is the only star whose surface can be imaged at high resolution. I found that the full-disc magnetic flux is an excellent proxy for activity-induced radial-velocity variations; this result may become key to breaking the activity barrier in coming

  15. Study on a multi-delay spectral interferometry for stellar radial velocity measurement

    NASA Astrophysics Data System (ADS)

    Zhang, Kai; Jiang, Haijiao; Tang, Jin; Ji, Hangxin; Zhu, Yongtian; Wang, Liang

    2014-08-01

    High accuracy radial velocity measurement isn't only one of the most important methods for detecting earth-like Exoplanets, but also one of the main developing fields of astronomical observation technologies in future. Externally dispersed interferometry (EDI) generates a kind of particular interference spectrum through combining a fixed-delay interferometer with a medium-resolution spectrograph. It effectively enhances radial velocity measuring accuracy by several times. Another further study on multi-delay interferometry was gradually developed after observation success with only a fixed-delay, and its relative instrumentation makes more impressive performance in near Infrared band. Multi-delay is capable of giving wider coverage from low to high frequency in Fourier field so that gives a higher accuracy in radial velocity measurement. To study on this new technology and verify its feasibility at Guo Shoujing telescope (LAMOST), an experimental instrumentation with single fixed-delay named MESSI has been built and tested at our lab. Another experimental study on multi-delay spectral interferometry given here is being done as well. Basically, this multi-delay experimental system is designed in according to the similar instrument named TEDI at Palomar observatory and the preliminary test result of MESSI. Due to existence of LAMOST spectrograph at lab, a multi-delay interferometer design actually dominates our work. It's generally composed of three parts, respectively science optics, phase-stabilizing optics and delay-calibrating optics. To switch different fixed delays smoothly during observation, the delay-calibrating optics is possibly useful to get high repeatability during switching motion through polychromatic interferometry. Although this metrology is based on white light interferometry in theory, it's different that integrates all of interference signals independently obtained by different monochromatic light in order to avoid dispersion error caused by

  16. Toward accurate radial velocities with the fiber-fed GIRAFFE multi-object VLT spectrograph

    NASA Astrophysics Data System (ADS)

    Royer, Frederic; Blecha, Andre; North, Pierre; Simond, Gilles; Baratchart, Sebastien; Cayatte, Veronique; Chemin, Laurent; Palsa, Ralf

    2002-12-01

    We describe briefly the Data-Reduction of the VLT fiber-fed multi-object GIRAFFE spectrograph - part of the VLT FLAMES facility. We focus on specific features of GIRAFFE - the simultaneous wavelength calibration - and their impact on the data-reduction strategy. We describe the implementation of the global physical model and we compare the results obtained with the simulated, laboratory and preliminary data. We discuss the influence of critical parameters, the overall accuracy of the wavelength solution, and the stability and the robustness of the global model approach. We address the accuracy of radial velocity measurements illustrated by solar spectra obtained during the Preliminary Acceptance in Europe.

  17. Near-infrared metallicities, radial velocities, and spectral types for 447 nearby M dwarfs

    SciTech Connect

    Newton, Elisabeth R.; Charbonneau, David; Irwin, Jonathan; Berta-Thompson, Zachory K.; Rojas-Ayala, Barbara; Covey, Kevin; Lloyd, James P.

    2014-01-01

    We present metallicities, radial velocities, and near-infrared (NIR) spectral types for 447 M dwarfs determined from moderate resolution (R ≈ 2000) NIR spectra obtained with the NASA Infrared Telescope Facility (IRTF)/SpeX. These M dwarfs are primarily targets of the MEarth Survey, a transiting planet survey searching for super Earths around mid-to-late M dwarfs within 33 pc. We present NIR spectral types for each star and new spectral templates for the IRTF in the Y, J, H, and K-bands, created using M dwarfs with near-solar metallicities. We developed two spectroscopic distance calibrations that use NIR spectral type or an index based on the curvature of the K-band continuum. Our distance calibration has a scatter of 14%. We searched 27 NIR spectral lines and 10 spectral indices for metallicity sensitive features, taking into account correlated noise in our estimates of the errors on these parameters. We calibrated our relation using 36 M dwarfs in common proper pairs with an F-, G-, or K-type star of known metallicity. We validated the physical association of these pairs using proper motions, radial velocities, and spectroscopic distance estimates. Our resulting metallicity calibration uses the sodium doublet at 2.2 μm as the sole indicator for metallicity. It has an accuracy of 0.12 dex inferred from the scatter between the metallicities of the primaries and the estimated metallicities of the secondaries. Our relation is valid for NIR spectral types from M1V to M5V and for –1.0 dex < [Fe/H] < +0.35 dex. We present a new color-color metallicity relation using J – H and J – K colors that directly relates two observables: the distance from the M dwarf main sequence and equivalent width of the sodium line at 2.2 μm. We used radial velocities of M dwarf binaries, observations at different epochs, and comparison between our measurements and precisely measured radial velocities to demonstrate a 4 km s{sup –1} accuracy.

  18. Activity induced detection limits for Earth-sized planets from radial velocity studies

    NASA Astrophysics Data System (ADS)

    Korhonen, Heidi; Gråe Jørgensen, Uffe; Andersen, Jan Marie

    2015-08-01

    The detection of exoplanets using any method is prone to confusion due to the intrinsic variability of the host star. We have recently investigated the effect of cool starspots on the detectability of exoplanets around solar-like stars and M dwarfs using the radial velocity method. Our methods use full radiative transfer, known stellar atomic and molecular lines, different surface spot configurations, and an added planetary signal. In this talk we present our methods, and apply them to studying the detectability of small planets, and especially the case of alpha Centauri B planet.

  19. Telluric Line Effect on High Precision Radial Velocity Survey of K and M Dwarfs

    NASA Astrophysics Data System (ADS)

    Sithajan, Sirinrat; Ge, Jian; Wang, Ji

    2016-01-01

    The red and NIR region, where K and M dwarfs emit most of light, is the desirable region for radial velocity (RV) measurements for detecting low mass planets, but this wavelength region is heavily contaminated with telluric absorption lines. Variation in the telluric line depths and centroids can result in large RV measurement uncertainties, limiting the sensitivity to detect low mass planets. Here we use simulations to study effect of telluric removal and the residuals on RV measurements and determine the level of correction needed to minimize the effect. Simulated spectra from three representative spectrographs with spectral resolutions, R=60K, 80K, 100K and 120K for wavelength coverage at 0.38-0.62 μm (called the optical spectrograph), 0.38-0.90 μm (called the broad optical spectrograph) and 0.90-2.4 μm (called the NIR spectrograph), have been studied. Two methods are used to study the RV effect by the telluric lines. The first one is a 'Masking' method, in which the telluric lines are identified and removed from RV calculation. The other method is a 'Removal' method, in which all heavily saturated lines are masked out and the remaining lines are subtracted by synthetic atmospheric spectra to a desired level. Our results show that, in case of late M dwarfs, the broad optical spectrograph can gain additional RV sensitivity over the optical spectrograph if telluric lines can be modeled and subtracted to better than 10%, or all lines deeper than 5% are masked out from RV calculation. For the earlier type stars, it requires better than 2% modeling and subtracting precision with the broad optical spectrograph to gain additional Doppler sensitivity over the optical spectrograph. Besides the photon gain with the NIR spectrograph over the optical spectrograph for late M dwarf observations, the NIR can gain additional advantage of Doppler sensitivity over the optical tool for late M dwarfs when telluric residuals can be subtracted to below 1%. However, it is never

  20. Searching for IMBHs in Galactic globular clusters through radial velocities of individual stars

    NASA Astrophysics Data System (ADS)

    Lanzoni, Barbara

    2016-02-01

    I present an overview of our ongoing project aimed at building a new generation of velocity dispersion profiles ad rotation curves for a representative sample of Galactic globular clusters, from the the radial velocity of hundreds of individual stars distributed at different distances from the cluster center. The innermost portion of the profiles will be used to constrain the possible presence of intermediate-mass black holes. The adopted methodology consists of combining spectroscopic observations acquired with three different instruments at the ESO-VLT: the adaptive-optics assisted, integral field unit (IFU) spectrograph SINFONI for the innermost and highly crowded cluster cores, the multi-IFU spectrograph KMOS for the intermediate regions, and the multi-fiber instrument FLAMES/GIRAFFE-MEDUSA for the outskirts. The case of NGC 6388, representing the pilot project that motivated the entire program, is described in some details.

  1. The Radial Velocity Signature and Line Diagnostics Arising from Realistic, Rotating Stellar Plage Models

    NASA Astrophysics Data System (ADS)

    Saar, Steven; Dumusque, Xavier

    2015-08-01

    The radial velocity (RV) signature of starspots has been well-studied and methods to mitigate for them have been developed. The RV signature of magnetic plage is smaller, but more complex (since plage differs from its surroundings more by velocity than intensity) and less well understood. There are reasons however to expect that RV jitter from plage may be important, especially in low to moderate activity stars. We explore the RV effects of stellar plage by taking spatially resolved solar line bisectors in and out of plage at various limb angles to construct semi-empirical stellar intensity profiles profiles of different strengths. These lines are placed on model stars with various plage configurations, rotated, and disk-integrated. The resulting spectra are analyzed to yield the RV and various line and cross-correlation profile diagnostics as a function of rotational phase. We discuss the results and some ideas for mitigating the inferred RV signatures.

  2. Astrophysical Sources of Statistical Uncertainty in Precision Radial Velocities and Their Approximations

    NASA Astrophysics Data System (ADS)

    Beatty, Thomas G.; Gaudi, B. Scott

    2015-12-01

    We investigate various astrophysical contributions to the statistical uncertainty of precision radial velocity measurements of stellar spectra. We first analytically determine the intrinsic uncertainty in centroiding isolated spectral lines broadened by Gaussian, Lorentzian, Voigt, and rotational profiles, finding that for all cases and assuming weak lines, the uncertainty in the line centroid is σV ≈ C\\Theta3/2/(WI1/20), where Θ is the full-width at half-maximum of the line, W is the equivalent width, and I0 is the continuum signal-to-noise ratio, with C a constant of order unity that depends on the specific line profile. We use this result to motivate approximate analytic expressions to the total radial velocity uncertainty for a stellar spectrum with a given photon noise, resolution, wavelength, effective temperature, surface gravity, metallicity, macroturbulence, and stellar rotation. We use these relations to determine the dominant contributions to the statistical uncertainties in precision radial velocity measurements as a function of effective temperature and mass for main-sequence stars. For stars more massive than ~1.1 Msolar we find that stellar rotation dominates the velocity uncertainties for moderate and high-resolution spectra (R gsim 30,000). For less-massive stars, a variety of sources contribute depending on the spectral resolution and wavelength, with photon noise due to decreasing bolometric luminosity generally becoming increasingly important for low-mass stars at fixed exposure time and distance. In most cases, resolutions greater than 60,000 provide little benefit in terms of statistical precision, although higher resolutions would likely allow for better control of systematic uncertainties. We find that the spectra of cooler stars and stars with higher metallicity are intrinsically richer in velocity information, as expected. We determine the optimal wavelength range for stars of various spectral types, finding that the optimal region

  3. Relativistic Velocity Addition Law from Machine Gun Analogy

    ERIC Educational Resources Information Center

    Rothenstein, Bernhard; Popescu, Stefan

    2009-01-01

    Many derivations of the relativistic addition law of parallel velocities without use of the Lorentz transformations (LT) are known. Some of them are based on thought experiments that require knowledge of the time dilation and the length contraction effects. Other derivations involve the Doppler effect in the optic domain considered from three…

  4. A More Intuitive Version of the Lorentz Velocity Addition Formula

    ERIC Educational Resources Information Center

    Devlin, John F.

    2009-01-01

    The Lorentz velocity addition formula for one-dimensional motion presents a number of problems for beginning students of special relativity. In this paper we suggest a simple rewrite of the formula that is easier for students to memorize and manipulate, and furthermore is more intuitive in understanding the correction necessary when adding…

  5. The Milky Way's halo in 6D: Gaia's Radial Velocity Spectrometer performance

    NASA Astrophysics Data System (ADS)

    Seabroke, George; Cropper, Mark; Katz, David; Sartoretti, Paola; Panuzzo, Pasquale; Marchal, Olivier; Gueguen, Alain; Benson, Kevin; Dolding, Chris; Huckle, Howard; Smith, Mike; Baker, Steve

    2016-08-01

    Gaia's Radial Velocity Spectrometer (RVS) has been operating in routine phase for over one year since initial commissioning. RVS continues to work well but the higher than expected levels of straylight reduce the limiting magnitude. The end-of-mission radial-velocity (RV) performance requirement for G2V stars was 15 km s-1 at V = 16.5 mag. Instead, 15 km s-1 precision is achieved at 15 < V < 16 mag, consistent with simulations that predict a loss of 1.4 mag. Simulations also suggest that changes to Gaia's onboard software could recover ~0.14 mag of this loss. Consequently Gaia's onboard software was upgraded in April 2015. The status of this new commissioning period is presented, as well as the latest scientific performance of the on-ground processing of RVS spectra. We illustrate the implications of the RVS limiting magnitude on Gaia's view of the Milky Way's halo in 6D using the Gaia Universe Model Snapshot (GUMS).

  6. Precision radial-velocity measurements on bright Sun-like stars

    NASA Astrophysics Data System (ADS)

    Dixit, Vaibhav; Chaturvedi, Priyanka; Chakraborty, Abhijit; Mahadevan, Suvrath; Roy, Arpita; Dongre, Varun

    We at PRL have initiated for the first time in India an Exoplanet search program using the precision Radial Velocity (RV) technique. The program is called PARAS (PRL Advanced Radial-velocity All-sky Search) and consists of a high resolution, optical fiber-fed, cross-dispersed, Echelle spectrograph. The spectrograph works at a resolution (R) of 67000, in the wavelength range of 3700 Å -- 8400 Å and is coupled with the PRL Mt. Abu 1.2~m telescope. We present here time series RV measurements on RV standard stars like sigma Draconics, 47 UMa and tau Ceti at 2 to sub-2m/s precision. Thus, in principle PARAS can detect exoplanets of masses down to 10 Earth mass at 0.1AU distances or less around 1 to 0.5 Solar Mass stars. Since many of the bright G and K dwarfs are yet to be surveyed at sub-2m/s RV precision at high cadence, this opens up new science opportunities for highly stabilized high resolution spectrographs like PARAS attached to 1m-class telescopes. The PARAS echelle spectrograph is installed in a temperature controlled chamber (0.03C rms at 25C) and inside a vacuum vessel for both temperature and pressure stability.

  7. The Milky Way’s halo in 6D: Gaia's Radial Velocity Spectrometer performance

    NASA Astrophysics Data System (ADS)

    Seabroke, George; Cropper, Mark; Katz, David; Sartoretti, Paola; Panuzzo, Pasquale; Marchal, Olivier; Gueguen, Alain; Benson, Kevin; Dolding, Chris; Huckle, Howard; Smith, Mike; Baker, Steve

    2015-08-01

    Gaia's Radial Velocity Spectrometer (RVS) has been operating in routine phase for nearly one year since initial commissioning. RVS continues to work well but the higher than expected levels of stray light reduce the limiting magnitude. The end-of-mission radial velocity performance requirements are 15 km/s for G2V stars at V = 16.5 mag. 15 km/s accuracy is achieved at V ~ 15 mag, in agreement with simulations that predict a loss of 1.4 mag. Simulations also suggest that changes to Gaia’s onboard software could recover ~0.1 mag of this loss. Consequently Gaia's onboard software will be upgraded in spring/summer 2015 (TBC). The status of this new commissioning period will be presented, as well as the latest scientific performance of the on-ground processing of RVS spectra. The implications of the RVS limiting magnitude on Gaia’s view of the Milky Way’s halo in 6D will be illustrated using the Gaia Universe Model Snapshot (GUMS).

  8. PlanetPack3: a software tool for exoplanets characterization from radial velocity and transit data

    NASA Astrophysics Data System (ADS)

    Baluev, Roman V.

    2015-08-01

    We describe the forthcoming third major release of the PlanetPack software tool for exoplanets detection and characterization from Doppler and/or transit data. Among other things, this major update will bring routines for the joint fitting of radial velocities and transits, optionally taking into account various subtle effects: the Rossiter-McLaughlin effect, the light arrival time delay between the radial velocity and transit curves, new experimental models of the Doppler or photometry noise, including non-stationary models with variable noise magnitude (due to e.g. the stellar activity variations).This work was supported by the Russian Foundation for Basic Research (project No. 14-02-92615 KO_a), the UK Royal Society International Exchange grant IE140055, by the President of Russia grant for young scientists (No. MK-733.2014.2), by the programme of the Presidium of Russian Academy of Sciences P21, and by the Saint Petersburg State University research grant 6.37.341.2015.

  9. No Evidence for Activity Correlations in the Radial Velocities of Kapteyn’s Star

    NASA Astrophysics Data System (ADS)

    Anglada-Escudé, G.; Tuomi, M.; Arriagada, P.; Zechmeister, M.; Jenkins, J. S.; Ofir, A.; Dreizler, S.; Gerlach, E.; Marvin, C. J.; Reiners, A.; Jeffers, S. V.; Butler, R. Paul; Vogt, S. S.; Amado, P. J.; Rodríguez-López, C.; Berdiñas, Z. M.; Morin, J.; Crane, J. D.; Shectman, S. A.; Díaz, M. R.; Sarmiento, L. F.; Jones, H. R. A.

    2016-10-01

    Stellar activity may induce Doppler variability at the level of a few m s‑1 which can then be confused by the Doppler signal of an exoplanet orbiting the star. To first order, linear correlations between radial velocity measurements and activity indices have been proposed to account for any such correlation. The likely presence of two super-Earths orbiting Kapteyn’s star was reported in Anglada-Escudé et al., but this claim was recently challenged by Robertson et al., who argued for evidence of a rotation period (143 days) at three times the orbital period of one of the proposed planets (Kapteyn’s b, P = 48.6 days) and the existence of strong linear correlations between its Doppler signal and activity data. By re-analyzing the data using global statistics and model comparison, we show that such a claim is incorrect given that (1) the choice of a rotation period at 143 days is unjustified, and (2) the presence of linear correlations is not supported by the data. We conclude that the radial velocity signals of Kapteyn’s star remain more simply explained by the presence of two super-Earth candidates orbiting it. We note that analysis of time series of activity indices must be executed with the same care as Doppler time series. We also advocate for the use of global optimization procedures and objective arguments, instead of claims based on residual analyses which are prone to biases and incorrect interpretations.

  10. Twenty Years of Precise Radial Velocities at Keck and Lick Observatories

    NASA Astrophysics Data System (ADS)

    Wright, J. T.

    2015-10-01

    The precise radial velocity survey at Keck Observatory began over 20 years ago. Its survey of thousands of stars now has the time baseline to be sensitive to planets with decade-long orbits, including Jupiter analogs. I present several newly-finished orbital solutions for long-period giant planets. Although hot Jupiters are generally ``lonely'' (i.e. they are not part of multiplanet systems), those that are not appear to often have giant companions at 5 AU or beyond. I present two of the highest period-ratios among planets in a two-planet system, and some of the longest orbital periods ever measured for exoplanets. In many cases, combining Keck radial velocities from those from other long-term surveys at Lick Observatory, McDonald Observatory, HARPS, and, of course, OHP spectrographs, produces superior orbital fits, constraining both period and eccentricity better than could be possible with any single set alone. Stellar magnetic activity cycles can masquerade as long-period planets. In most cases this effect is very small, but a loud minority of stars, including, apparently, HD 154345, show very strong RV-activity correlations.

  11. SOAP. A tool for the fast computation of photometry and radial velocity induced by stellar spots

    NASA Astrophysics Data System (ADS)

    Boisse, I.; Bonfils, X.; Santos, N. C.

    2012-09-01

    We define and put at the disposal of the community SOAP, Spot Oscillation And Planet, a software tool that simulates the effect of stellar spots and plages on radial velocimetry and photometry. This paper describes the tool release and provides instructions for its use. We present detailed tests with previous computations and real data to assess the code's performance and to validate its suitability. We characterize the variations of the radial velocity, line bisector, and photometric amplitude as a function of the main variables: projected stellar rotational velocity, filling factor of the spot, resolution of the spectrograph, linear limb-darkening coefficient, latitude of the spot, and inclination of the star. Finally, we model the spot distributions on the active stars HD 166435, TW Hya and HD 189733, which reproduce the observations. We show that the software is remarkably fast, allowing several evolutions in its capabilities that could be performed to study the next challenges in the exoplanetary field connected with the stellar variability. The tool is available at http://www.astro.up.pt/soap

  12. VizieR Online Data Catalog: Radial velocities of 1 Gem (Lane+, 2014)

    NASA Astrophysics Data System (ADS)

    Lane, B. F.; Muterspaugh, M. W.; Griffin, R. F.; Scarfe, C. D.; Fekel, F. C.; Williamson, M. H.; Eaton, J. A.; Shao, M.; Colavita, M. M.; Konacki, M.

    2016-05-01

    Extensive radial-velocity measurements of the 1 Gem system have been obtained in four separate campaigns spanning 40yr, including data from eight different instruments. Between 1969 and 2009 R.F.G. acquired a total of 128 observations of 1 Gem using the original radial-velocity spectrometer at Cambridge; a second-generation, computerized instrument at Palomar; the CORAVEL spectrometer at Haute Provence Observatory (OHP), and most recently, the Cambridge CORAVEL. The "Cambridge CORAVEL" operates at the Coude focus of the 36inch reflector on the home site of the Cambridge Observatories, Madingley Road, Cambridge, England. The Cambridge and Palomar data are referred to as data set A, while the OHP data are labeled set B. The data for components A and Ba are provided in Table1. A series of observations of 1 Gem has been obtained by C.D.S. with the Dominion Astrophysical Observatory (DAO) radial-velocity spectrometer. Observations were begun early in 1980 and continued until the end of 2003. The DAO velocities of components A and Ba are listed in Table2. The total number of acceptable velocities from DAO radial-velocity scanner observations is 123 of the primary star and 107 of the brighter component of the close pair. The third component was not detectable in the DAO traces. We identify the DAO observations as data set C. >From 1983 through 2009 F.C.F. obtained observations at the Kitt Peak National Observatory (KPNO) with the 0.9m coude feed telescope, coude spectrograph, and several different CCD detectors. All of the spectrograms were acquired with a Texas Instruments (TI) CCD except for five that were obtained in 1983 with an RCA CCD and a single observation in 2008 September with a Tektronix CCD. All those observations were centered near 6430Å and had typical signal-to-noise ratios of about 250. The numerous TI CCD spectra have a wavelength range of just 84Å and a resolution of 0.21Å. The 86 velocities of component A and 80 of component Ba are listed in Table3

  13. Fast retrospectively triggered local pulse-wave velocity measurements in mice with CMR-microscopy using a radial trajectory

    PubMed Central

    2013-01-01

    Background The aortic pulse-wave velocity (PWV) is an important indicator of cardiovascular risk. In recent studies MRI methods have been developed to measure this parameter noninvasively in mice. Present techniques require additional hardware for cardiac and respiratory gating. In this work a robust self-gated measurement of the local PWV in mice without the need of triggering probes is proposed. Methods The local PWV of 6-months-old wild-type C57BL/6J mice (n=6) was measured in the abdominal aorta with a retrospectively triggered radial Phase Contrast (PC) MR sequence using the flow-area (QA) method. A navigator signal was extracted from the CMR data of highly asymmetric radial projections with short repetition time (TR=3 ms) and post-processed with high-pass and low-pass filters for retrospective cardiac and respiratory gating. The self-gating signal was used for a reconstruction of high-resolution Cine frames of the aortic motion. To assess the local PWV the volume flow Q and the cross-sectional area A of the aorta were determined. The results were compared with the values measured with a triggered Cartesian and an undersampled triggered radial PC-Cine sequence. Results In all examined animals a self-gating signal could be extracted and used for retrospective breath-gating and PC-Cine reconstruction. With the non-triggered measurement PWV values of 2.3±0.2 m/s were determined. These values are in agreement with those measured with the triggered Cartesian (2.4±0.2 m/s) and the triggered radial (2.3±0.2 m/s) measurement. Due to the strong robustness of the radial trajectory against undersampling an acceleration of more than two relative to the prospectively triggered Cartesian sampling could be achieved with the retrospective method. Conclusion With the radial flow-encoding sequence the extraction of a self-gating signal is feasible. The retrospective method enables a robust and fast measurement of the local PWV without the need of additional trigger hardware

  14. CHARACTERIZING THE GALACTIC WHITE DWARF BINARY POPULATION WITH SPARSELY SAMPLED RADIAL VELOCITY DATA

    SciTech Connect

    Maoz, Dan; Badenes, Carles; Bickerton, Steven J. E-mail: badenes@pitt.edu

    2012-06-01

    We present a method to characterize statistically the parameters of a detached binary sample-binary fraction, separation distribution, and mass-ratio distribution-using noisy radial velocity data with as few as two, randomly spaced, epochs per object. To do this, we analyze the distribution of {Delta}RV{sub max}, the maximum radial velocity difference between any two epochs for the same object. At low values, the core of this distribution is dominated by measurement errors, but for large enough samples there is a high-velocity tail that can effectively constrain the parameters of the binary population. We discuss our approach for the case of a population of detached white dwarf (WD) binaries with separations that are decaying via gravitational wave emission. We derive analytic expressions for the present-day distribution of separations, integrated over the star formation history of the Galaxy, for parameterized initial WD separation distributions at the end of the common-envelope phase. We use Monte Carlo techniques to produce grids of simulated {Delta}RV{sub max} distributions with specific binary population parameters, and the same sampling cadences and radial velocity errors as the observations, and we compare them to the real {Delta}RV{sub max} distribution to constrain the properties of the binary population. We illustrate the sensitivity of the method to both the model and observational parameters. In the particular case of binary WDs, every model population predicts a merger rate per star which can easily be compared to specific Type Ia supernova rates. In a companion paper, we apply the method to a sample of {approx}4000 WDs from the Sloan Digital Sky Survey. The binary fractions and separation distribution parameters allowed by the data indicate a rate of WD-WD mergers per unit stellar mass in the Galactic disk, {approx}1 Multiplication-Sign 10{sup -13} mergers yr{sup -1} M{sup -1}{sub Sun }, remarkably similar to the rate per unit mass of Type Ia

  15. Theoretical and Experimental Study of Radial Velocity Generation for Extending Bandwidth of Magnetohydrodynamic Angular Rate Sensor at Low Frequency.

    PubMed

    Ji, Yue; Li, Xingfei; Wu, Tengfei; Chen, Cheng

    2015-12-15

    The magnetohydrodynamics angular rate sensor (MHD ARS) has received much attention for its ultra-low noise in ultra-broad bandwidth and its impact resistance in harsh environments; however, its poor performance at low frequency hinders its work in long time duration. The paper presents a modified MHD ARS combining Coriolis with MHD effect to extend the measurement scope throughout the whole bandwidth, in which an appropriate radial flow velocity should be provided to satisfy simplified model of the modified MHD ARS. A method that can generate radial velocity by an MHD pump in MHD ARS is proposed. A device is designed to study the radial flow velocity generated by the MHD pump. The influence of structure and physical parameters are studied by numerical simulation and experiment of the device. The analytic expression of the velocity generated by the energized current drawn from simulation and experiment are consistent, which demonstrates the effectiveness of the method generating radial velocity. The study can be applied to generate and control radial velocity in modified MHD ARS, which is essential for the two effects combination throughout the whole bandwidth.

  16. Theoretical and Experimental Study of Radial Velocity Generation for Extending Bandwidth of Magnetohydrodynamic Angular Rate Sensor at Low Frequency

    PubMed Central

    Ji, Yue; Li, Xingfei; Wu, Tengfei; Chen, Cheng

    2015-01-01

    The magnetohydrodynamics angular rate sensor (MHD ARS) has received much attention for its ultra-low noise in ultra-broad bandwidth and its impact resistance in harsh environments; however, its poor performance at low frequency hinders its work in long time duration. The paper presents a modified MHD ARS combining Coriolis with MHD effect to extend the measurement scope throughout the whole bandwidth, in which an appropriate radial flow velocity should be provided to satisfy simplified model of the modified MHD ARS. A method that can generate radial velocity by an MHD pump in MHD ARS is proposed. A device is designed to study the radial flow velocity generated by the MHD pump. The influence of structure and physical parameters are studied by numerical simulation and experiment of the device. The analytic expression of the velocity generated by the energized current drawn from simulation and experiment are consistent, which demonstrates the effectiveness of the method generating radial velocity. The study can be applied to generate and control radial velocity in modified MHD ARS, which is essential for the two effects combination throughout the whole bandwidth. PMID:26694393

  17. Theoretical and Experimental Study of Radial Velocity Generation for Extending Bandwidth of Magnetohydrodynamic Angular Rate Sensor at Low Frequency.

    PubMed

    Ji, Yue; Li, Xingfei; Wu, Tengfei; Chen, Cheng

    2015-01-01

    The magnetohydrodynamics angular rate sensor (MHD ARS) has received much attention for its ultra-low noise in ultra-broad bandwidth and its impact resistance in harsh environments; however, its poor performance at low frequency hinders its work in long time duration. The paper presents a modified MHD ARS combining Coriolis with MHD effect to extend the measurement scope throughout the whole bandwidth, in which an appropriate radial flow velocity should be provided to satisfy simplified model of the modified MHD ARS. A method that can generate radial velocity by an MHD pump in MHD ARS is proposed. A device is designed to study the radial flow velocity generated by the MHD pump. The influence of structure and physical parameters are studied by numerical simulation and experiment of the device. The analytic expression of the velocity generated by the energized current drawn from simulation and experiment are consistent, which demonstrates the effectiveness of the method generating radial velocity. The study can be applied to generate and control radial velocity in modified MHD ARS, which is essential for the two effects combination throughout the whole bandwidth. PMID:26694393

  18. Kepler beaming binaries radial velocity follow-up with WIYN/Hydra

    NASA Astrophysics Data System (ADS)

    Shporer, Avi; Stassun, Keivan; Faigler, Simchon; Mazeh, Tsevi; Boyajian, Tabetha S.; Tal-Or, Lev; Prsa, Andrej

    2016-01-01

    High-quality space-based time series photometry reveals the minute photometric modulations induced by orbital motion in short-period binary systems with stellar and substellar secondaries. Those modulations are induced by both gravitational and atmospheric processes. Gravitational processes include the beaming effect (aka Doppler boosting) and tidal ellipsoidal distortion, and the atmospheric processes include reflected light and thermal emission by the secondary atmosphere. Therefore, non-eclipsing systems are detectable using photometry alone. The availability of Kepler data for a large sample of stars combined with the sensitivity to non-eclipsing systems has the potential of transforming the Kepler survey into the equivalent of a radial velocity (RV) survey of a large sample of stars with a wide range of spectral type. This allows detecting intrinsically rare systems, where traditional approaches, e.g., RV and transit surveys, are highly inefficient. Those include systems where the companion is a brown-dwarf or a massive planet, or even a white dwarf. As this approach is still in its infancy, we are carrying out RV follow-up of Kepler photometric detections, to confirm the nature of the system and measure the orbit and the companion's mass. Here we present our results from an RV campaign with the WIYN/Hydra multi-fiber spectrograph, where we used 26 nights so far during the 2014 and 2015 Kepler observing seasons to observe 5 Hydra one-degree diameter fields within the Kepler field. Our list of targets includes 131 Kepler beaming binary candidates, and we used additional fibers to observe 85 Kepler eclipsing binaries and 31 KOIs. A detailed comparison between the photometrically predicted companion's mass and the mass measured through RVs will improve our understanding of this young approach, and will support similar projects using data from current and future space-based time series photometry missions including K2, TESS, and PLATO. Our primary long term goal

  19. Radial Velocities and Kinematic Membership in the Open Cluster NGC 3114

    NASA Astrophysics Data System (ADS)

    González, Jorge Federico; Lapasset, Emilio

    2001-05-01

    Echelle spectroscopic observations for 30 bright stars in the field of the sparse open cluster NGC 3114 are presented. The sample includes main-sequence stars, yellow and red giants, and blue straggler candidates. Radial velocities are derived by cross-correlations using high signal-to-noise ratio standard spectra as templates. The cluster mean velocity is well defined from eight giants and several main-sequence stars whose average is =-3.52+/-0.25 km s-1. The membership probabilities of the observed stars are computed on the basis of the velocity distributions of the cluster and field stars, and the expected percentage of contamination at each position. We classified 19 cluster members and 10 nonmembers; the remaining star is a known spectroscopic binary for which no membership probability was assigned. Among the members, there is a bright yellow giant, seven red giants, and four blue straggler candidates, although they should be considered as turn-off stars. The location of two of them in the color-magnitude diagram (slightly blueward of the turn-off) can be explained by their low rotational velocities. No velocity variations were detected in the 16 stars measured more than once, which indicates that NGC 3114 possess an abnormally low binary frequency. From spectral types of cluster members, a distance modulus (V-Mv)=9.8+/-0.2 mag and a reddening E(B-V)=0.07+/-0.01 mag are derived. The cluster age is estimated to be 1.6×108 yr. The observations presented here were obtained at the Complejo Astronómico El Leoncito (CASLEO), which is operated under agreement between the Consejo Nacional de Investigaciones Científicas y Técnicas de la República Argentina (CONICET) and the National Universities of La Plata, Córdoba and San Juan.

  20. The Gaia-ESO Survey: Empirical determination of the precision of stellar radial velocities and projected rotation velocities

    NASA Astrophysics Data System (ADS)

    Jackson, R. J.; Jeffries, R. D.; Lewis, J.; Koposov, S. E.; Sacco, G. G.; Randich, S.; Gilmore, G.; Asplund, M.; Binney, J.; Bonifacio, P.; Drew, J. E.; Feltzing, S.; Ferguson, A. M. N.; Micela, G.; Neguerela, I.; Prusti, T.; Rix, H.-W.; Vallenari, A.; Alfaro, E. J.; Allende Prieto, C.; Babusiaux, C.; Bensby, T.; Blomme, R.; Bragaglia, A.; Flaccomio, E.; Francois, P.; Hambly, N.; Irwin, M.; Korn, A. J.; Lanzafame, A. C.; Pancino, E.; Recio-Blanco, A.; Smiljanic, R.; Van Eck, S.; Walton, N.; Bayo, A.; Bergemann, M.; Carraro, G.; Costado, M. T.; Damiani, F.; Edvardsson, B.; Franciosini, E.; Frasca, A.; Heiter, U.; Hill, V.; Hourihane, A.; Jofré, P.; Lardo, C.; de Laverny, P.; Lind, K.; Magrini, L.; Marconi, G.; Martayan, C.; Masseron, T.; Monaco, L.; Morbidelli, L.; Prisinzano, L.; Sbordone, L.; Sousa, S. G.; Worley, C. C.; Zaggia, S.

    2015-08-01

    Context. The Gaia-ESO Survey (GES) is a large public spectroscopic survey at the European Southern Observatory Very Large Telescope. Aims: A key aim is to provide precise radial velocities (RVs) and projected equatorial velocities (vsini) for representative samples of Galactic stars, which will complement information obtained by the Gaia astrometry satellite. Methods: We present an analysis to empirically quantify the size and distribution of uncertainties in RV and vsini using spectra from repeated exposures of the same stars. Results: We show that the uncertainties vary as simple scaling functions of signal-to-noise ratio (S/N) and vsini, that the uncertainties become larger with increasing photospheric temperature, but that the dependence on stellar gravity, metallicity and age is weak. The underlying uncertainty distributions have extended tails that are better represented by Student's t-distributions than by normal distributions. Conclusions: Parametrised results are provided, which enable estimates of the RV precision for almost all GES measurements, and estimates of the vsini precision for stars in young clusters, as a function of S/N, vsini and stellar temperature. The precision of individual high S/N GES RV measurements is 0.22-0.26 km s-1, dependent on instrumental configuration. Based on observations collected with the FLAMES spectrograph at VLT/UT2 telescope (Paranal Observatory, ESO, Chile), for the Gaia- ESO Large Public Survey (188.B-3002).Full Table 2 is only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/580/A75

  1. RADIAL VELOCITY OFFSETS DUE TO MASS OUTFLOWS AND EXTINCTION IN ACTIVE GALACTIC NUCLEI

    SciTech Connect

    Crenshaw, D. M.; Schmitt, H. R.; Kraemer, S. B.; Mushotzky, R. F.

    2010-01-01

    We present a study of the radial velocity offsets between narrow emission lines and host galaxy lines (stellar absorption and H I 21 cm emission) in Seyfert galaxies with observed redshifts less than 0.043. We find that 35% of the Seyferts in the sample show [O III] emission lines with blueshifts with respect to their host galaxies exceeding 50 km s{sup -1}, whereas only 6% show redshifts this large, in qualitative agreement with most previous studies. We also find that a greater percentage of Seyfert 1 galaxies show blueshifts than Seyfert 2 galaxies. Using Hubble Spce Talescope/Space Telescope Imaging Spectrograph spatially resolved spectra of the Seyfert 2 galaxy NGC 1068 and the Seyfert 1 galaxy NGC 4151, we generate geometric models of their narrow-line regions (NLRs) and inner galactic disks, and show how these models can explain the blueshifted [O III] emission lines in collapsed STIS spectra of these two Seyferts. We conclude that the combination of mass outflow of ionized gas in the NLR and extinction by dust in the inner disk (primarily in the form of dust spirals) is primarily responsible for the velocity offsets in Seyfert galaxies. More exotic explanations are not needed. We discuss the implications of this result for the velocity offsets found in higher redshift active galactic nuclei.

  2. Radial velocities of very low mass stars and candidate brown dwarf members of the Hyades and Pleiades

    NASA Technical Reports Server (NTRS)

    Stauffer, John R.; Liebert, James; Giampapa, Mark; Macintosh, Bruce; Reid, Neill; Hamilton, Donald

    1994-01-01

    We have determined H alpha equivalent widths and radial velocities with 1 sigma accuracies of approximately 5 km s(exp -1) for approximately 20 candidate very low mass members of the Hyades and Pleiades clusters. The radial velocities for the Hyades sample suggest that nearly all of these stars are indeed highly probable members of the Hyades. The faintest stars in the Hyades sample have masses of order 0.1 solar mass. We also obtained radial velocities for four candidate very low mass members of the Pleiades and two objects that are candidate BD Pleiads. All of these stars have apparent V magnitudes fainter than the Hyades stars we observed, and the resultant radial velocity accuracy is worse. We believe that the three brighter stars are indeed likely very low mass stellar members of the Pleiades, whereas the status of the two brown dwarf candidates is uncertain. The Hyades stars we have observed and the three Pleiades very low mass stars are the lowest mass members of any open cluster whose membership has been confirmed by radial velocities and whose chromospheric activity has been measured. We see no change in chromospheric activity at the boundary where stars are expected to become fully convective (M approximately equals 0.3 solar mass) in either cluster. In the Pleiades, however, there may be a decrease in chromospheric activity for stars with (V-I)(sub K) greater than 3.5 (M less than or equal to 0.1 solar mass).

  3. Solar radial velocity variations and the search for Venus enabled by a laser frequency comb

    NASA Astrophysics Data System (ADS)

    Phillips, David F.; Dumusque, Xavier; Li, Chih-Hao; Glenday, Alexander; Sasselov, Dimitar; Szentgyorgyi, Andrew; Walsworth, Ronald L.

    2016-05-01

    We have recently demonstrated 50 cm/s sensitivity in measuring the radial velocity (RV) between the Earth and Sun using a simple, compact solar telescope feeding the HARPS-N spectrograph at the Italian National Telescope calibrated with our green astro-comb. The green astro-comb is a laser frequency comb optimized for calibrating astrophysical spectrographs. We have been operating the solar telescope to detect the RV signal of the Sun as a star for the past year both to study RV jitter associated with stellar (solar) fluctuations and to demonstrate sensitivity of these instruments to detect terrestrial exoplanets. In this talk I will present results from calibrating the HARPS-N exoplanet searcher spectrograph, solar RV stability, and the current status of our search for the signature of Venus.

  4. Radial velocity measurements of the chromospherically-active stars (2): HD 28591 = V492 Per

    NASA Technical Reports Server (NTRS)

    Dadonas, V.; Sperauskas, J.; Fekel, F. C.; Morton, M. D.

    1994-01-01

    From two sets of the spectroscopic observations covering a ten year period we have obtained 59 radial velocities of the chromospherically-active star HD 28591 = V492 Per. It is a G9III single-lined spectroscopic binary with a period of 21.2910 days and a circular orbit. The upsilon sin i of 24.6 km/sec, results in a minimum radius 10.3 solar radii. We estimate a distance of 165 +/- 40 pc and an orbital inclination of 65 +/- 25 degrees. The secondary is probably a mid to late-type K dwarf. The star is brighter than the limiting magnitude of the Bright Star Catalogue. The mean photometric and the orbital periods are identical within their uncertainties. Since the star fills a significant fraction of its Roche lobe, about 62%, the photometric light curve may be the result of starspots and a modest ellipticity effect.

  5. A WEAVE Radial Velocity Survey to Unravel the Nature of the Milky Way's Spiral Arms

    NASA Astrophysics Data System (ADS)

    Monguió, M.; Figueras, F.; Grosbøl, P.

    2016-10-01

    The nature of the spiral arms of our Milky Way Galaxy is still a matter of debate. Different theories have been suggested (density waves, swing amplification, invariant manifolds...) which impose several constraints on the observables. For the first time it will be possible to disentangle these theories by combining Gaia and WEAVE data. Great advantage comes from the fact that WEAVE is in the Northern Hemisphere, that is with good coverage towards the galactic anticenter. We plan to quantify the kinematic perturbation induced by the Perseus spiral arm through radial velocity measurements. We show how, for the first time, we have detected the stellar overdensity associated with the Perseus arm using a Strömgren photometric survey with the Wide Field Camera on the Isaac Newton Telescope. This survey has allowed us to perform first tests on WEAVE capabilities.

  6. SKARPS: The Search for Kuiper Belts around Radial-Velocity Planet Stars

    NASA Technical Reports Server (NTRS)

    Bryden, Geoffrey; Marshall, Jonathan; Stapelfeldt, Karl; Su, Kate; Wyatt, Mark

    2011-01-01

    The Search for Kuiper belts Around Radial-velocity Planet Stars - SKARPS -is a Herschel survey of solar-type stars known to have orbiting planets. When complete, the 100-star SKARPS sample will be large enough for a meaningful statistical comparison against stars not known to have planets. (This control sample has already been observed by Herschel's DUst around NEarby Stars - DUNES - key program). Initial results include previously known disks that are resolved for the first time and newly discovered disks that are fainter and colder than those typically detected by Spitzer. So far, with only half of the sample in hand, there is no measured correlation between inner RV planets and cold outer debris. While this is consistent with the results from Spitzer, it is in contrast with the relationship suggested by the prominent debris disks in imaged-planet systems.

  7. Analytical determination of orbital elements using Fourier analysis. I. The radial velocity case

    NASA Astrophysics Data System (ADS)

    Delisle, J.-B.; Ségransan, D.; Buchschacher, N.; Alesina, F.

    2016-05-01

    We describe an analytical method for computing the orbital parameters of a planet from the periodogram of a radial velocity signal. The method is very efficient and provides a good approximation of the orbital parameters. The accuracy is mainly limited by the accuracy of the computation of the Fourier decomposition of the signal which is sensitive to sampling and noise. Our method is complementary with more accurate (and more expensive in computer time) numerical algorithms (e.g. Levenberg-Marquardt, Markov chain Monte Carlo, genetic algorithms). Indeed, the analytical approximation can be used as an initial condition to accelerate the convergence of these numerical methods. Our method can be applied iteratively to search for multiple planets in the same system.

  8. Radial Velocity Searches for Extra Solar Planets from Keck and McDonald Observatories

    NASA Astrophysics Data System (ADS)

    Hatzes, Artie P.; Cochran, William D.

    We review several programs using precise stellar radial velocity measurements to search for extra solar planets. Two programs that are conducted from the Keck Observatory using the HIRES spectrograph are discussed. The Cochran & Hatzes Hyades program is searching for extra-solar planets among members of the Hyades cluster. These stars represent a homogeneous population that allows us to probe the characteristics of planetary systems primarily as a function of stellar mass. The Marcy et al. Keck program is searching for planets among 400 of the brightest G-M dwarfs. The McDonald Observatory Planet Search Program is a multi-faceted program that not only searches for planets around a sample of bright F-M dwarfs, but also uses high resolution spectral data to place constraints on companion masses as well as confirm extra-solar planet discoveries.

  9. VizieR Online Data Catalog: HARPS radial velocities of GJ 163 (Bonfils+, 2013)

    NASA Astrophysics Data System (ADS)

    Bonfils, X.; Lo Curto, G.; Correia, A. C. M.; Laskar, J.; Udry, S.; Delfosse, X.; Forveille, T.; Astudillo-Defru, N.; Benz, W.; Bouchy, F.; Gillon, M.; Hebrard, G.; Lovis, C.; Mayor, M.; Moutou, C.; Naef, D.; Neves, V.; Pepe, F.; Perrier, C.; Queloz, D.; Santos, N. C.; Segransan, D.

    2013-08-01

    We observed GJ 163 with HARPS, a spectrograph fiber-fed by the ESO/3.6m telescope of La Silla Observatory. Our settings and computation of radial velocities (RV) remained the same as for our GTO program and we refer the reader to Bonfils et al. (2013A&A...549A.109B) for a detailed description. We gathered RVs for 154 epochs spread over 2988 days (8.2 years) between UT 30 October 2003 and 04 January 2012. Table 6 (available in electronic form) lists all RVs in the barycentric reference frame of the Solar System. Four measurements have significantly higher uncertainties (the RVs taken at epochs BJD=2454804.7, 2455056.9, 2455057.9 and, 2455136.8 have uncertainties greater than twice the median uncertainty). We removed them and perform our analysis with the remaining 150 RVs. (1 data file).

  10. Reanalysis of radial velocity data from the resonant planetary system HD128311

    NASA Astrophysics Data System (ADS)

    Rein, Hanno

    2015-03-01

    The multiplanetary system HD128311 hosts at least two planets. Its dynamical formation history has been studied extensively in the literature. We reanalyse the latest radial velocity data for this system with the affine-invariant Markov chain Monte Carlo sampler EMCEE. Using the high-order integrator IAS15, we perform a fully dynamical fit, allowing the planets to interact during the sampling process. A stability analysis using the Mean Exponential Growth of Nearby Orbits indicator reveals that the system is located in a stable island of the parameter space. In contrast to a previous study, we find that the system is locked in a 2:1 mean motion resonance. The resonant angle ϕ1 is librating with a libration amplitude of approximately 37°. The existence of mean motion resonances has important implication for planet formation theories. Our results confirm predictions of models involving planet migration and stochastic forces.

  11. Study of Optical Mode Scrambling of Fiber Optics for High Precision Radial Velocity Measurements

    NASA Astrophysics Data System (ADS)

    Cassette, Anthony; Ge, Jian; Jeram, Sarik; Klanot, Khaya; Ma, Bo; Varosi, Frank

    2016-01-01

    Optical Fibers have been used throughout Astronomy for spectroscopy with spectrographs located some distance away from the telescope. This fiber-fed design has greatly increased precision for radial velocity (RV) measurements. However, due to the incomplete fiber illumination mode scrambling in the radial direction, high resolution spectrographs with regular circular fibers have suffered RV uncertainties on the order of a few to tens of m/s with stellar observations, which largely limited their sensitivity in detecting and characterizing low mass planets around stars. At the University of Florida, we studied mode scrambling gain of a few different optical devices, such as three-lens optical double scramblers, octagonal fibers and low numerical aperture fibers with a goal to find an optimal mode scrambling solution for the TOU optical very high resolution spectrograph (R=100,000, 0.38-0.9 microns) and FIRST near infrared high resolution spectrograph (R=60,000, 0.9-1.8 microns) for the on-going Dharma Planet Survey. This presentation will report our lab measurement results and also stellar RV measurements at the observatories.

  12. The VLT-FLAMES Tarantula Survey. XVIII. Classifications and radial velocities of the B-type stars

    NASA Astrophysics Data System (ADS)

    Evans, C. J.; Kennedy, M. B.; Dufton, P. L.; Howarth, I. D.; Walborn, N. R.; Markova, N.; Clark, J. S.; de Mink, S. E.; de Koter, A.; Dunstall, P. R.; Hénault-Brunet, V.; Maíz Apellániz, J.; McEvoy, C. M.; Sana, H.; Simón-Díaz, S.; Taylor, W. D.; Vink, J. S.

    2015-02-01

    We present spectral classifications for 438 B-type stars observed as part of the VLT-FLAMES Tarantula Survey (VFTS) in the 30 Doradus region of the Large Magellanic Cloud. Radial velocities are provided for 307 apparently single stars, and for 99 targets with radial-velocity variations which are consistent with them being spectroscopic binaries. We investigate the spatial distribution of the radial velocities across the 30 Dor region, and use the results to identify candidate runaway stars. Excluding potential runaways and members of two older clusters in the survey region (SL 639 and Hodge 301), we determine a systemic velocity for 30 Dor of 271.6 ± 12.2 kms-1 from 273 presumed single stars. Employing a 3σ criterion we identify nine candidate runaway stars (2.9% of the single stars with radial-velocity estimates). The projected rotational velocities of the candidate runaways appear to be significantly different to those of the full B-type sample, with a strong preference for either large (≥345 kms-1) or small (≤65 kms-1) rotational velocities. Of the candidate runaways, VFTS 358 (classified B0.5: V) has the largest differential radial velocity (-106.9 ± 16.2 kms-1), and a preliminary atmospheric analysis finds a significantly enriched nitrogen abundance of 12 + log (N/H) ≳ 8.5. Combined with a large rotational velocity (vesini = 345 ± 22 kms-1), this is suggestive of past binary interaction for this star. Table 7 and Appendix A are available in electronic form at http://www.aanda.org

  13. A multi-method approach to radial-velocity measurement for single-object spectra

    NASA Astrophysics Data System (ADS)

    David, M.; Blomme, R.; Frémat, Y.; Damerdji, Y.; Delle Luche, C.; Gosset, E.; Katz, D.; Viala, Y.

    2014-02-01

    Context. The derivation of radial velocities from large numbers of spectra that typically result from survey work, requires automation. However, except for the classical cases of slowly rotating late-type spectra, existing methods of measuring Doppler shifts require fine-tuning to avoid a loss of accuracy due to the idiosyncrasies of individual spectra. The radial velocity spectrometer (RVS) on the Gaia mission, which will start operating very soon, prompted a new attempt at creating a measurement pipeline to handle a wide variety of spectral types. Aims: The present paper describes the theoretical background on which this software is based. However, apart from the assumption that only synthetic templates are used, we do not rely on any of the characteristics of this instrument, so our results should be relevant for most telescope-detector combinations. Methods: We propose an approach based on the simultaneous use of several alternative measurement methods, each having its own merits and drawbacks, and conveying the spectral information in a different way, leading to different values for the measurement. A comparison or a combination of the various results either leads to a "best estimate" or indicates to the user that the observed spectrum is problematic and should be analysed manually. Results: We selected three methods and analysed the relationships and differences between them from a unified point of view; with each method an appropriate estimator for the individual random error is chosen. We also develop a procedure for tackling the problem of template mismatch in a systematic way. Furthermore, we propose several tests for studying and comparing the performance of the various methods as a function of the atmospheric parameters of the observed objects. Finally, we describe a procedure for obtaining a knowledge-based combination of the various Doppler-shift measurements.

  14. Technology for radial velocity search and characterisation of exoplanets in the 2020s and beyond

    NASA Astrophysics Data System (ADS)

    Ireland, Michael; Feger, Tobias; Bento, Joao; Rains, Adam

    2015-12-01

    In the past 20 years, radial velocity exoplanet instrumentation has been focussed on a small number of moderate sized (or moderate efficiency) telescopes. I will argue that there are two very different uses for radial velocity in the near future: transit follow-up and low-mass exoplanet detection around relatively nearby stars. For the first of these science goals, targets are relatively distant, and a high eficiency spectrograph on a large telescope is needed, for example the Gemini High-resolution Optical SpecTrograph (GHOST): a stabilised spectrograph fed by an array of multi-mode fibers at the final design stage. For the second of these goals, stellar noise due to pulsations, convective cells and activity provide a lower limit to the noise floor achievable for any given temporal sampling. I will argue through simple simulations that an array of small telescopes with precise spectrographs making a very large number of measurements is a much more effective way to detect the smallest exoplanets than instrumentation on large telescopes. I will describe the first results from the Replicable High-Resoluition Exoplanet and Asteroseismology (RHEA) spectrograph designed for 0.25 to 0.5m telescopes, which has single-epoch measurement uncertainties at the 1 m/s level and a total whole cost for detecting the smallest exoplanets that is significantly lower than medium to large telescope concepts. RHEA has an eyepiece-sized fast tip/tilt and mode reformatting system that efficiently injects a small array of single-mode fibers, feeding a <0.5m sized stabilised inexpensive spectrograph. I will show preliminary performance results from both stars and laboratory tests that verify the precision, and will discuss pathways to turn this into a broader community project.

  15. Chromospherically Active Stars in the RAdial Velocity Experiment (RAVE) Survey. I. The Catalog

    NASA Astrophysics Data System (ADS)

    Žerjal, M.; Zwitter, T.; Matijevič, G.; Strassmeier, K. G.; Bienaymé, O.; Bland-Hawthorn, J.; Boeche, C.; Freeman, K. C.; Grebel, E. K.; Kordopatis, G.; Munari, U.; Navarro, J. F.; Parker, Q. A.; Reid, W.; Seabroke, G.; Siviero, A.; Steinmetz, M.; Wyse, R. F. G.

    2013-10-01

    RAVE, the unbiased magnitude limited survey of southern sky stars, contained 456,676 medium-resolution spectra at the time of our analysis. Spectra cover the Ca II infrared triplet (IRT) range, which is a known indicator of chromospheric activity. Our previous work classified all spectra using locally linear embedding. It identified 53,347 cases with a suggested emission component in calcium lines. Here, we use a spectral subtraction technique to measure the properties of this emission. Synthetic templates are replaced by the observed spectra of non-active stars to bypass the difficult computations of non-local thermal equilibrium profiles of the line cores and stellar parameter dependence. We derive both the equivalent width of the excess emission for each calcium line on a 5 Å wide interval and their sum EWIRT for ~44,000 candidate active dwarf stars with signal-to-noise ratio >20, with no cuts on the basis of the source of their emission flux. From these, ~14,000 show a detectable chromospheric flux with at least a 2σ confidence level. Our set of active stars vastly enlarges previously known samples. Atmospheric parameters and, in some cases, radial velocities of active stars derived from automatic pipelines suffer from systematic shifts due to their shallower calcium lines. We re-estimate the effective temperature, metallicity, and radial velocities for candidate active stars. The overall distribution of activity levels shows a bimodal shape, with the first peak coinciding with non-active stars and the second with the pre-main-sequence cases. The catalog will be made publicly available with the next RAVE public data releases.

  16. Radial-Velocity Analysis of the Post-AGB Star, HD101584

    NASA Astrophysics Data System (ADS)

    Díaz, F.; Hearnshaw, J.; Rosenzweig, P.; Guzman, E.; Sivarani, T.; Parthasarathy, M.

    2007-08-01

    This project concerns the analysis of the periodicity of the radial velocity of the peculiar emission-line supergiant star HD 101584 (F0 Ia), and also we propose a physical model to account for the observations. From its peculiarities, HD 101584 is a star that is in the post-AGB phase. This study is considered as a key to clarify the multiple aspects related with the evolution of the circum-stellar layer associated with this star's last phase. The star shows many lines with P Cygni profiles, including H-alpha, Na D lines in the IR Ca triplet, indicating a mass outflow. For HD 101584 we have performed a detailed study of its radial-velocity variations, using both emission and absorption lines over a wide range of wavelength. We have analyzed the variability and found a periodicity for all types of lines of 144 days, which must arise from the star's membership in a binary system. The data span a period of five consecutive years and were obtained using the 1-m telescope of Mt John Observatory, in New Zealand., with the echelle and Hercules high resolution spectrographs and CCD camera. HD101584 is known to be an IRAS source, and our model suggests it is a proto-planetary nebula, probably with a bipolar outflow and surrounded by a dusty disk as part of a binary system. We have found no evidence for HD101584 to contain a B9 star as found by Bakker et al (1996). A low resolution IUE spectrum shows the absence of any strong UV continuum that would be expected for a B star to be in this system.

  17. The SDSS-III APOGEE radial velocity survey of M dwarfs. I. Description of the survey and science goals

    SciTech Connect

    Deshpande, R.; Bender, C. F.; Mahadevan, S.; Terrien, R. C.; Schneider, D. P.; Fleming, S. W.; Blake, C. H.; Carlberg, J. K.; Zasowski, G.; Hearty, F.; Crepp, J.; Rajpurohit, A. S.; Reylé, C.; Nidever, D. L.; Prieto, C. Allende; Hernández, J.; Bizyaev, D.; Ebelke, G.; Frinchaboy, P. M.; Ge, J.; and others

    2013-12-01

    We are carrying out a large ancillary program with the Sloan Digital Sky Survey, SDSS-III, using the fiber-fed multi-object near-infrared APOGEE spectrograph, to obtain high-resolution H-band spectra of more than 1200 M dwarfs. These observations will be used to measure spectroscopic rotational velocities, radial velocities, physical stellar parameters, and variability of the target stars. Here, we describe the target selection for this survey, as well as results from the first year of scientific observations based on spectra that will be publicly available in the SDSS-III DR10 data release. As part of this paper we present radial velocities and rotational velocities of over 200 M dwarfs, with a vsin i precision of ∼2 km s{sup –1} and a measurement floor at vsin i = 4 km s{sup –1}. This survey significantly increases the number of M dwarfs studied for rotational velocities and radial velocity variability (at ∼100-200 m s{sup –1}), and will inform and advance the target selection for planned radial velocity and photometric searches for low-mass exoplanets around M dwarfs, such as the Habitable Zone Planet Finder, CARMENES, and TESS. Multiple epochs of radial velocity observations enable us to identify short period binaries, and adaptive optics imaging of a subset of stars enables the detection of possible stellar companions at larger separations. The high-resolution APOGEE spectra, covering the entire H band, provide the opportunity to measure physical stellar parameters such as effective temperatures and metallicities for many of these stars. At the culmination of this survey, we will have obtained multi-epoch spectra and radial velocities for over 1400 stars spanning the spectral range M0-L0, providing the largest set of near-infrared M dwarf spectra at high resolution, and more than doubling the number of known spectroscopic vsin i values for M dwarfs. Furthermore, by modeling telluric lines to correct for small instrumental radial velocity shifts, we

  18. Binaries at Birth: Stellar multiplicity in embedded clusters from radial velocity variations in the IN-SYNC survey

    NASA Astrophysics Data System (ADS)

    Oskar Jaehnig, Karl; Stassun, Keivan; Tan, Jonathan C.; Covey, Kevin R.; Da Rio, Nicola

    2016-01-01

    We study the nature of stellar multiplicity in young stellar systems using the INfrared Spectroscopy of Young Nebulous Clusters (IN-SYNC) survey, carried out in SDSS III with the APOGEE spectrograph. Multi-epoch observations of thousands of low-mass stars in Orion A, NGC2264, NGC1333 and IC348 have been carried out, yielding H-band spectra with R=22,500 for sources with H<12 mag. Radial velocity sensitivities ~0.3 km/s can be achieved, depending on the spectral type of the star. We search the IN-SYNC radial velocity catalog to identify sources with radial velocity variations indicative of spectroscopically undetected companions, analyze their spectral properties and discuss the implications for the overall multiplicity of stellar populations in young, embedded star clusters.

  19. Eigenmodes of Ducted Flows With Radially-Dependent Axial and Swirl Velocity Components

    NASA Technical Reports Server (NTRS)

    Kousen, Kenneth A.

    1999-01-01

    This report characterizes the sets of small disturbances possible in cylindrical and annular ducts with mean flow whose axial and tangential components vary arbitrarily with radius. The linearized equations of motion are presented and discussed, and then exponential forms for the axial, circumferential, and time dependencies of any unsteady disturbances are assumed. The resultant equations form a generalized eigenvalue problem, the solution of which yields the axial wavenumbers and radial mode shapes of the unsteady disturbances. Two numerical discretizations are applied to the system of equations: (1) a spectral collocation technique based on Chebyshev polynomial expansions on the Gauss-Lobatto points, and (2) second and fourth order finite differences on uniform grids. The discretized equations are solved using a standard eigensystem package employing the QR algorithm. The eigenvalues fall into two primary categories: a discrete set (analogous to the acoustic modes found in uniform mean flows) and a continuous band (analogous to convected disturbances in uniform mean flows) where the phase velocities of the disturbances correspond to the local mean flow velocities. Sample mode shapes and eigensystem distributions are presented for both sheared axial and swirling flows. The physics of swirling flows is examined with reference to hydrodynamic stability and completeness of the eigensystem expansions. The effect of assuming exponential dependence in the axial direction is discussed.

  20. Suppression of fiber modal noise induced radial velocity errors for bright emission-line calibration sources

    SciTech Connect

    Mahadevan, Suvrath; Halverson, Samuel; Ramsey, Lawrence; Venditti, Nick

    2014-05-01

    Modal noise in optical fibers imposes limits on the signal-to-noise ratio (S/N) and velocity precision achievable with the next generation of astronomical spectrographs. This is an increasingly pressing problem for precision radial velocity spectrographs in the near-infrared (NIR) and optical that require both high stability of the observed line profiles and high S/N. Many of these spectrographs plan to use highly coherent emission-line calibration sources like laser frequency combs and Fabry-Perot etalons to achieve precision sufficient to detect terrestrial-mass planets. These high-precision calibration sources often use single-mode fibers or highly coherent sources. Coupling light from single-mode fibers to multi-mode fibers leads to only a very low number of modes being excited, thereby exacerbating the modal noise measured by the spectrograph. We present a commercial off-the-shelf solution that significantly mitigates modal noise at all optical and NIR wavelengths, and which can be applied to spectrograph calibration systems. Our solution uses an integrating sphere in conjunction with a diffuser that is moved rapidly using electrostrictive polymers, and is generally superior to most tested forms of mechanical fiber agitation. We demonstrate a high level of modal noise reduction with a narrow bandwidth 1550 nm laser. Our relatively inexpensive solution immediately enables spectrographs to take advantage of the innate precision of bright state-of-the art calibration sources by removing a major source of systematic noise.

  1. Radial Velocity and Metallicity Determinations for Remote Globular Clusters in M31 and M33

    NASA Astrophysics Data System (ADS)

    Ferguson, Annette; Barmby, Pauline; Cote, Pat; Harris, Bill; Huxor, Avon; Mackey, Dougal; Puzia, Thomas

    2009-08-01

    We propose to determine radial velocities and metallicities for a sample of ~ 20 remote globular clusters (GCs) which we have discovered in the outer halos of the Local Group galaxies M31 and M33. Most of these objects have been uncovered in the course of the PAndAs survey, an international collaboration which is using CFHT/MegaPrime to map more than 300 square degrees in the g and i bands around M31 and M33. The target clusters, all of which have been identified from high- quality imaging (typically ≲ 0.8'' seeing), lie at projected radii of up to 130 kpc from M31 and 30 kpc from M33 and thus lie significantly beyond all previously-known GCs in these systems. Rather intriguingly, many of the new discoveries exhibit either possible associations with halo tidal streams, or show unusual spatial anisotropies with respect to their host galaxy. Velocity and metallicity data for these objects will provide a detailed characterization of the ensemble properties of the outer halo GC populations, and, through the search for kinematic and metallicity correlations within groups of GCs, help determine what fraction of these objects can be attributed to either late or ongoing accretion events. Ultimately, these data will also provide a basis for improved dynamical mass estimates of both galaxies.

  2. VizieR Online Data Catalog: IN-SYNC. III. Radial velocities of IC348 stars (Cottaar+, 2015)

    NASA Astrophysics Data System (ADS)

    Cottaar, M.; Covey, K. R.; Foster, J. B.; Meyer, M. R.; Tan, J. C.; Nidever, D. L.; Drew Chojnowski, S.; da Rio, N.; Flaherty, K. M.; Frinchaboy, P. M.; Majewski, S.; Skrutskie, M. F.; Wilson, J. C.; Zasowski, G.

    2015-11-01

    Cottaar et al. (Paper I, 2014, J/ApJ/794/125) describes the analysis of the high-resolution near-infrared spectra obtained by the APOGEE multi-object spectrograph from stars in IC 348, NGC 1333, NGC 2264, and Orion A as part of the INfrared Spectroscopy of Young Nebulous Clusters (IN-SYNC) ancillary program. Using radial velocities determined from APOGEE spectra of 380 likely cluster members, we have measured the radial velocity distribution of the young (2-6Myr) cluster IC 348. (2 data files).

  3. Astrometry, radial velocity, and photometry: the HD 128311 system remixed with data from HST, HET, and APT

    SciTech Connect

    McArthur, Barbara E.; Benedict, G. Fritz.; Cochran, William D.; Henry, Gregory W.; Hatzes, Artie; Harrison, Tom E.; Johns-Krull, Chris; Nelan, Ed

    2014-11-01

    We have used high-cadence radial velocity measurements from the Hobby-Eberly Telescope with published velocities from the Lick 3 m Shane Telescope, combined with astrometric data from the Hubble Space Telescope (HST) Fine Guidance Sensors to refine the orbital parameters of the HD 128311 system, and determine an inclination of 55.°95 ± 14.°55 and true mass of 3.789 {sub −0.432}{sup +0.924} M {sub JUP} for HD 128311 c. The combined radial velocity data also reveal a short period signal which could indicate a third planet in the system with an Msin i of 0.133 ± 0.005 M {sub JUP} or stellar phenomena. Photometry from the T12 0.8 m automatic photometric telescope at the Fairborn Observatory and HST are used to determine a photometric period close to, but not within the errors of the radial velocity signal. We performed a cross-correlation bisector analysis of the radial velocity data to look for correlations with the photometric period and found none. Dynamical integrations of the proposed system show long-term stability with the new orbital parameters of over 10 million years. Our new orbital elements do not support the claims of HD 128311 b and c being in mean motion resonance.

  4. Proper-motion binaries in the Hipparcos catalogue. Comparison with radial velocity data

    NASA Astrophysics Data System (ADS)

    Frankowski, A.; Jancart, S.; Jorissen, A.

    2007-03-01

    Context: This paper is the last in a series devoted to the analysis of the binary content of the Hipparcos Catalogue. Aims: The comparison of the proper motions constructed from positions spanning a short (Hipparcos) or long time (Tycho-2) makes it possible to uncover binaries with periods of the order of or somewhat larger than the short time span (in this case, the 3 yr duration of the Hipparcos mission), since the unrecognised orbital motion will then add to the proper motion. Methods: A list of candidate proper motion binaries is constructed from a carefully designed χ2 test evaluating the statistical significance of the difference between the Tycho-2 and Hipparcos proper motions for 103 134 stars in common between the two catalogues (excluding components of visual systems). Since similar lists of proper-motion binaries have already been constructed, the present paper focuses on the evaluation of the detection efficiency of proper-motion binaries, using different kinds of control data (mostly radial velocities). The detection rate for entries from the Ninth Catalogue of Spectroscopic Binary Orbits (S_B^9) is evaluated, as well as for stars like barium stars, which are known to be all binaries, and finally for spectroscopic binaries identified from radial velocity data in the Geneva-Copenhagen survey of F and G dwarfs in the solar neighbourhood. Results: Proper motion binaries are efficiently detected for systems with parallaxes in excess of ~20 mas, and periods in the range 1000-30 000 d. The shortest periods in this range (1000-2000 d, i.e., once to twice the duration of the Hipparcos mission) may appear only as DMSA/G binaries (accelerated proper motion in the Hipparcos Double and Multiple System Annex). Proper motion binaries detected among S_B9 systems having periods shorter than about 400 d hint at triple systems, the proper-motion binary involving a component with a longer orbital period. A list of 19 candidate triple systems is provided. Binaries

  5. VizieR Online Data Catalog: HIP binaries with radial velocities (Frankowski+, 2007)

    NASA Astrophysics Data System (ADS)

    Frankowski, A.; Jancart, S.; Jorissen, A.

    2006-11-01

    The comparison of the proper motions constructed from positions spanning a short (Hipparcos) or long time (Tycho-2) makes it possible to uncover binaries with periods of the order of or somewhat larger than the short time span (in this case, the 3 yr duration of the Hipparcos mission), since the unrecognised orbital motion will then add to the proper motion. A list of candidate proper motion binaries is constructed from a chi-square test evaluating the statistical significance of the difference between the Tycho-2 and Hipparcos proper motions for 103134 stars in common between the two catalogues (excluding components of visual systems). The present paper focuses on the evaluation of the detection efficiency of proper-motion binaries, using different kinds of control data (mostly radial velocities). The detection rate for entries from the Ninth Catalogue of Spectroscopic Binary Orbits (SB9) is evaluated, as well as for stars like barium stars, which are known to be all binaries, and finally for spectroscopic binaries identified from radial velocity data in the Geneva-Copenhagen survey of F and G dwarfs in the solar neighbourhood. Proper motion binaries are efficiently detected for systems with parallaxes in excess of 20mas, and periods in the range 1000-30000d. The shortest periods in this range (1000-2000d, i.e., once to twice the duration of the Hipparcos mission) may appear only as DMSA/G binaries (accelerated proper motion in the Hipparcos Double and Multiple System Annex). Proper motion binaries detected among SB9 systems having periods shorter than about 400d hint at triple systems, the proper-motion binary involving a component with a longer orbital period. A list of 19 candidate triple systems is provided. Binaries suspected of having low-mass (brown-dwarf-like) companions are listed as well. Among the 37 barium stars with parallaxes larger than 5mas, only 7 exhibit no evidence for duplicity whatsoever (be it spectroscopic or astrometric). Finally, the

  6. A Search for Transits of Radial Velocity Detected Super-Earths

    NASA Astrophysics Data System (ADS)

    Kammer, Joshua A.; Knutson, H. A.; Howard, A. W.; Laughlin, G. P.

    2013-10-01

    Unlike hot Jupiters or other gas giants, super-Earths (planets with masses between 1-10 times that of Earth) are expected to have a wide variety of compositions, ranging from terrestrial bodies like our own to more gaseous planets like Neptune. Observations of transiting systems, which allow us to directly measure planet masses and radii and constrain atmospheric properties, are key to understanding the compositional diversity of the planets in this mass range. Although Kepler has discovered hundreds of transiting super-Earths over the past four years, the majority of these planets orbit stars that are too far away and too faint to allow for detailed atmospheric characterization and reliable mass estimates. Ground-based transit surveys focus on much brighter stars, but most lack the sensitivity to detect planets in this size range. One way to get around the difficulty of finding these smaller planets in transit is to start by choosing targets that are already known to contain super-Earth sized bodies detected using radial velocity techniques. Two of the three currently known transiting super-Earths around bright stars were discovered first by RV and then subsequently found to transit their host stars (55 Cnc e and HD 97658 b). Radial velocity measurements can be used to forecast expected transit times to within a ten to twenty hour window for many of the published super-Earth systems. Spitzer is an ideal platform for observing these targets, as it can observe the entire transit window in a single continuous span with enough sensitivity to detect transits for the full range of plausible planet sizes and compositions, many of which would be challenging to detect with typical ground-based facilities. We present results from a Spitzer program to observe six of the most favorable RV detected super-Earth systems: HD 1461, HD 7924, HD 97658, HD 156668, HIP 57274, and GJ 876. We find no evidence for transits in any of their 4.5 μm flux light curves, but place limits on

  7. WIYN open cluster study. LIX. Radial velocity membership of the evolved population of the old open cluster NGC 6791

    SciTech Connect

    Tofflemire, Benjamin M.; Gosnell, Natalie M.; Mathieu, Robert D.; Platais, Imants E-mail: imants@pha.jhu.edu

    2014-10-01

    The open cluster NGC 6791 has been the focus of much recent study due to its intriguing combination of old age and high metallicity (∼8 Gyr, [Fe/H] = +0.30), as well as its location within the Kepler field. As part of the WIYN Open Cluster Study, we present precise (σ = 0.38 km s{sup –1}) radial velocities for proper motion candidate members of NGC 6791 from Platais et al. Our survey, extending down to g' ∼ 16.8, is comprised of the evolved cluster population, including blue stragglers, giants, and horizontal branch stars. Of the 280 proper-motion-selected stars above our magnitude limit, 93% have at least one radial velocity measurement and 79% have three measurements over the course of at least 200 days, sufficient for secure radial-velocity-determined membership of non-velocity-variable stars. The Platais et al. proper motion catalog includes 12 anomalous horizontal branch candidates blueward of the red clump, of which we find only 4 to be cluster members. Three fall slightly blueward of the red clump and the fourth is consistent with being a blue straggler. The cleaned color-magnitude diagram shows a richly populated red giant branch and a blue straggler population. Half of the blue stragglers are in binaries. From our radial velocity measurement distribution, we find the cluster's radial velocity dispersion to be σ {sub c} = 0.62 ± 0.10 km s{sup –1}. This corresponds to a dynamical mass of ∼4600 M {sub ☉}.

  8. Rotational and Radial Velocities of 1.3-2.2 M ⊙ Red Giants in Open Clusters

    NASA Astrophysics Data System (ADS)

    Carlberg, Joleen K.

    2014-06-01

    This study presents the rotational distribution of red giant (RG) stars in 11 old to intermediate age open clusters. The masses of these stars are all above the Kraft break, so they lose negligible amounts of their birth angular momentum (AM) during the main-sequence (MS) evolution. However, they do span a mass range with quite different AM distributions imparted during formation, with the stars less massive than ~1.6M ⊙ arriving on the MS with lower rotation rates than the more massive stars. The majority of RGs in this study are slow rotators across the entire red giant branch regardless of mass, supporting the picture that intermediate-mass stars rapidly spin down when they evolve off the MS and develop convection zones capable of driving a magnetic dynamo. Nevertheless, a small fraction of RGs in open clusters show some level of enhanced rotation, and faster rotators are as common in these clusters as in the field RG population. Most of these enhanced rotators appear to be red clump stars, which is also true of the underlying stellar sample, while others are clearly RGs that are above or below the clump. In addition to rotational velocities, the radial velocities (RVs) and membership probabilities of individual stars are also presented. Cluster heliocentric RVs for NGC 6005 and Pismis 18 are reported for the first time.

  9. Rotational and radial velocities of 1.3-2.2 M {sub ☉} red giants in open clusters

    SciTech Connect

    Carlberg, Joleen K.

    2014-06-01

    This study presents the rotational distribution of red giant (RG) stars in 11 old to intermediate age open clusters. The masses of these stars are all above the Kraft break, so they lose negligible amounts of their birth angular momentum (AM) during the main-sequence (MS) evolution. However, they do span a mass range with quite different AM distributions imparted during formation, with the stars less massive than ∼1.6M {sub ☉} arriving on the MS with lower rotation rates than the more massive stars. The majority of RGs in this study are slow rotators across the entire red giant branch regardless of mass, supporting the picture that intermediate-mass stars rapidly spin down when they evolve off the MS and develop convection zones capable of driving a magnetic dynamo. Nevertheless, a small fraction of RGs in open clusters show some level of enhanced rotation, and faster rotators are as common in these clusters as in the field RG population. Most of these enhanced rotators appear to be red clump stars, which is also true of the underlying stellar sample, while others are clearly RGs that are above or below the clump. In addition to rotational velocities, the radial velocities (RVs) and membership probabilities of individual stars are also presented. Cluster heliocentric RVs for NGC 6005 and Pismis 18 are reported for the first time.

  10. VizieR Online Data Catalog: 2nd Cat. of Radial Velocities with Astrometric Data (Kharchenko+, 2007)

    NASA Astrophysics Data System (ADS)

    Kharchenko, N. V.; Scholz, R.-D.; Piskunov, A. E.; Roeser, S.; Schilbach, E.

    2007-06-01

    The catalogue of radial velocities of Galactic stars with high precision astrometric data, 2nd version (CRVAD-2), is the result of a merging of star lists from the All-Sky Compiled Catalogue of 2.5 Million Stars (ASCC-2.5, Cat. I/280) with the General Catalogue of Radial Velocities (GCRV, Cat. III/213) and with other recently published radial velocity lists and catalogues. Cross identification of objects was carried out with help of coordinate, magnitude, colour and/or spectral type criteria. Data from the Catalogue of Components of Double and Multiple Stars (CCDM, Cat. I/274) were taken into account for the identification of multiple system components. Altogether 54907 stars from the ASCC-2.5 were identified with 51762 stars from the RV source catalogues, 3085 stars have secondary components and 30 stars have 3rd components in multiple systems. The CRVAD-2 includes accurate J2000 equatorial coordinates, proper motions and trigonometric parallaxes in the Hipparcos system, Johnson's BV photometric data, spectral types, radial velocities, multiplicity and variability flags. Stars are sorted in the order of increasing right ascension J2000. This catalogue supersedes the previous version numbered . (1 data file).

  11. Joint Bayesian inversion of free oscillations and body waves for Earth's radial velocity and density structure

    NASA Astrophysics Data System (ADS)

    De Wit, R. W.; Valentine, A. P.; Trampert, J.

    2013-12-01

    Existing 1-D seismic models are the basis for 3-D seismic tomography and most earthquake location algorithms. It is therefore important to evaluate the quality of such 1-D reference models, yet quantifying uncertainties in seismological models is challenging. Ideally, quality assessment is an integral part of the inverse method. Our aim in this study is two-fold: (i) we show one approach to solving a Bayesian non-linear inverse problem and quantifying model uncertainties, and (ii) we analyse the constraint on radial P and S-wave velocity and density structure provided by normal mode and travel time data. We jointly invert body-wave travel times from the EHB bulletin (phases Pn, P, PP, PKP, Sn and S) and centre frequencies of recently measured splitting functions for the Earth's free oscillations up to 10 mHz. We adopt a machine learning approach to extract all information on the 1-D model that is available in the seismic data. We use artificial neural networks, which are very common in pattern recognition problems and can be used to approximate an arbitrary function. We obtain probability density functions (pdfs), which provide a quantitative description of our knowledge of the individual earth model parameters.

  12. The Latest Results from Project NIRRVS: Precise Near Infrared Radial Velocity Surveys

    NASA Astrophysics Data System (ADS)

    Plavchan, Peter; NIRRVS Collaboration

    2016-06-01

    We will present the latest results from a prototype PRV survey with CSHELL. With CSHELL at the NASA Infrared Telescope Facility atop Mauna Kea (R~46,000), we have completed a PRV 2.3 micron survey to detect exoplanets around ~30 red, low mass, and young stars. We are able to reach long-term radial velocity dispersions of ~30 m/s on our survey targets. We are following up candidate RV variables, and have confirmed other previously known RV variables. With a spectral grasp of only 5 nm at 2.3 microns, this performance with CSHELL is limited by detector artifacts, and fringing in the data and flatfields. iSHELL will replace CSHELL at IRTF, with first light expected in May 2016. iSHELL is a 1.15-5.4 micron high spectral resolution (R~70,000) immersion grating, cross-dispersed, white pupil spectrograph. With iSHELL we should be able to obtain a precision of less than 5 m/s in the NIR with iSHELL from the improvements in spectral grasp alone.

  13. Near-infrared calibration systems for precise radial-velocity measurements

    NASA Astrophysics Data System (ADS)

    Redman, Stephen L.; Kerber, Florian; Nave, Gillian; Mahadevan, Suvrath; Ramsey, Lawrence W.; Smoker, Jonathan; Käufl, Hans-Ulrich; Figueira, P. R. L.

    2012-09-01

    We present work done to prepare two new near-infrared calibration sources for use on high-precision astrophysical spectrographs. Uranium-neon is an atomic calibration source, commercially available as a hollow-cathode lamp, with over 10 000 known emission lines between 0.85 and 4 μm. Four gas cells — containing C2H2, H13CN, 12CO, and 13CO, respectively—are available as National Institute of Standards and Technology (nist) Standard Reference Materials (SRMs), and provide narrow absorption lines between 1.5 and 1.65 μm. These calibration sources may prove useful for wavelength-calibrating the future near-infrared high-precision radial-velocity spectrometers, including the Calar Alto high-Resolution search for M dwarfs with Exo-earths with a Near-infrared Echelle Spectrograph (CARMENES),1 the SpectroPolarimetre InfraROUge (SPIRou)∗, and the Habitable-Zone Planet Finder (HPF).2

  14. Radial velocity studies and absolute parameters of contact binaries. II - OO Aquilae

    NASA Technical Reports Server (NTRS)

    Hrivnak, Bruce J.

    1989-01-01

    New high-precision radial velocities of the contact binary OO Aql have been obtained using the cross-correlation technique. The orbital elements have been corrected for proximity effects, using an analysis of published light curves of the system. The spectroscopically determined mass ratio of 0.843 is in excellent agreement with the photometrically determined value. OO Aql thus has one of the largest mass ratios observed for a contact binary. In contrast to almost all other contact binaries of G spectral type, the primary minimum is due to a transit by the less massive component, and thus the system is classified as an A-type contact binary. Absolute parameters are determined for OO Aql, which indicate that the primary component, although similar to the Sun in mass, is significantly more evolved. An age of about 8 Gyr and a metal abundance of one-half that of the Sun are determined. It seems that the system may have only recently evolved into contact, as suggested by Mochnacki, and that it is an important object for studies of the structure and evolution of contact binaries.

  15. The Latest Results from Project NIRRVS: Precise Near Infrared Radial Velocity Surveys

    NASA Astrophysics Data System (ADS)

    Plavchan, Peter; NIRRVS Collaboration

    2016-01-01

    We will present the latest results from a prototype PRV survey with CSHELL. With CSHELL at the NASA Infrared Telescope Facility atop Mauna Kea (R~46,000), we have completed a PRV 2.3 micron survey to detect exoplanets around ~30 red, low mass, and young stars. We are able to reach long-term radial velocity dispersions of ~30 m/s on our survey targets. We are following up candidate RV variables, and have confirmed other previously known RV variables. With a spectral grasp of only 5 nm at 2.3 microns, this performance with CSHELL is limited by detector artifacts, and fringing in the data and flatfields. iSHELL will replace CSHELL at IRTF, with first light expected in April 2016. iSHELL is a 1.15-5.4 micron high spectral resolution (R~70,000) immersion grating, cross-dispersed, white pupil spectrograph. With iSHELL we should be able to obtain a precision of less than 5 m/s in the NIR with iSHELL from the improvements in spectral grasp alone.

  16. Retrieval of Precise Radial Velocities from High Resolution Near-Infrared Spectra of M Dwarfs

    NASA Astrophysics Data System (ADS)

    Gao, Peter; Plavchan, Peter; Gagne, Jonathan; Furlan, Elise; Bottom, Michael; Anglada-Escudé, Guillem; White, Russel J.; Davison, Cassy; Mills, Sean; Beichman, Charles A.; Brinkworth, Carolyn; Johnson, John; Ciardi, David R.; Wallace, J. Kent; Mennesson, Bertrand; von Braun, Kaspar; Vasisht, Gautam; Prato, Lisa A.; Kane, Stephen R.; Tanner, Angelle M.; Walp, Bernie; Crawford, Sam; Lin, Sean

    2015-01-01

    We present a data analysis pipeline focused on obtaining precision radial velocities (RV) of M Dwarfs from spectra taken between 2.309 and 2.316 microns by the CSHELL spectrograph (R~46,000) at NASA's Infrared Telescope Facility with the aid of a methane isotopologue gas cell (see poster by Plavchan et al. at this meeting). The pipeline compares the observed spectra with a forward model defined by parameters that are optimized using a simplex amoeba algorithm. The stellar template is optimized simultaneously with the fit parameters in an iterative process. The pipeline accounts for temporal variations in the spectral wavelength solution, line spread function, and interference fringes due to instrumental effects. We apply our pipeline to the M Dwarfs GJ 15 A and GJ 876 and the M Giant SV Peg. For GJ 15 A, we are able to obtain 30 m/s RV precision. For the planet host GJ 876, the two most massive planets are easily retrievable from our RV curve. For SV Peg, the single night RV precision can be as low as 15 m/s, with < 5 m/s obtainable through data stacking.

  17. Radial velocity studies of HeII and Hβ emission from cataclysmic variables

    NASA Astrophysics Data System (ADS)

    Schwarz, C.; Montgomery, M. M.

    2014-02-01

    Radial velocity (RV) plots of HeII and Hβ emission lines from non-magnetic Cataclysmic Variable (CV) systems are frequently fit with a sin curve but sometimes contain outlying data points around phase ϕ∼1.0. A lack of consensus exists on the origin of these outlying points. In this work, we develop an analytical model that is based upon our 3D Smoothed Particle Hydrodynamic (SPH) numerical model to simulate these RV curves. Our chosen targets are CV SW Sextanis-like systems UX Uma and RW Tri as well as SU UMa dwarf novae systems Hα0242-28 and 1RXSJ1808+10, which have secondary-to-primary mass ratios of q = (0.43, 0.86, 0.27, 0.18), respectively. In our model, we include disk eccentricity, inclination angle, degree of disk-tilt, bright spot (s), and/or gas stream overflow. Our model provides good non-sinusoidal fits to the observed RV data, including outlying data points near ϕ∼1.0, suggesting these excess points may be caused by gas-stream overflow.

  18. Identification of field dwarfs and giants in the second Radial Velocity Experiment Data Release

    NASA Astrophysics Data System (ADS)

    Bilir, S.; Karaali, S.; Ak, S.; Önal, Ö.; CoşkunoǧLu, B.; Seabroke, G. M.

    2011-11-01

    The second Radial Velocity Experiment (RAVE) Data Release (DR2) derives log g values. However, we present a simpler and cleaner method of identifying dwarfs and giants by using only magnitudes, which does not require spectroscopic analysis. We confirm the method presented in an earlier paper, with which we estimate the number of dwarfs and giants using their positions in the J-V two-magnitude diagram, by applying it to RAVE DR2. It is effective in estimating the number of dwarfs and giants at J-H > 0.4 compared to RAVE's log g values. For J-H≤ 0.4, where dwarfs and subgiants show a continuous transition in the J magnitude histogram, we used the Besançon Galaxy model predictions to statistically isolate giants. The percentages of giants for red stars and for the whole sample are 85 and 34 per cent, respectively. If we add the subgiants, the percentage of evolved stars for the whole sample increases to 59 per cent. For the first time in the literature, we have analysed the effect of CHISQ on RAVE's log g values (CHISQ is the penalized χ2 from RAVE's technique of finding an optimal match between the observed spectrum and synthetic spectra to derive stellar parameters). Neither the CHISQ values nor the signal-to-noise ratio bias the RAVE log g values. Therefore, the method of identifying dwarfs and giants using the two-magnitude diagram has been verified against an unbiased data set.

  19. Determination of U, V, and W from single station Doppler radar radial velocities

    NASA Technical Reports Server (NTRS)

    Clark, W. L.; Green, J. L.; Warnock, J. M.

    1986-01-01

    The ST/MST (stratosphere troposphere/mesosphere stratosphere troposphere) clear air Doppler radar, or wind profiler, is an important tool in observational meteorology because of its capability to remote observe dynamic parameters of the atmosphere. There are difficulties in transforming the observed radial velocities into meteorological wind components. How this problem has been treated in the past is reviewed, and some of the analysis is recast to a form more suited to the high diagnostic abilities of a number of fixed beam configurations with reference to a linear wind field. The results, in conjunction with other works which treats problems such as the effects of finite sample volumes in the presence of nonhomogeneous atmospheric reflectivity, have implications important to the design of both individual MST/ST radars and MST/ST radar networks. The key parameters to uncoupling terms in the scaling equations are w sub x and w sub y. Whenever the stratiform condition, which states that these two parameters are negligible, is satisfied, a five beam ST radar may determine unbiased values of u, v, and w for sample volumes directly above the radar. The divergence and partial deformation of the flow may also be determined. Three beam systems can determine w and w sub z, but are unable to obtain u and v wind components uncontaminated by vertical sheer terms, even when the stratiform condition is satisfied.

  20. High-contrast Imaging of Intermediate-mass Giants with Long-term Radial Velocity Trends

    NASA Astrophysics Data System (ADS)

    Ryu, Tsuguru; Sato, Bun'ei; Kuzuhara, Masayuki; Narita, Norio; Takahashi, Yasuhiro H.; Uyama, Taichi; Kudo, Tomoyuki; Kusakabe, Nobuhiko; Hashimoto, Jun; Omiya, Masashi; Harakawa, Hiroki; Abe, Lyu; Ando, Hiroyasu; Brandner, Wolfgang; Brandt, Timothy D.; Carson, Joseph C.; Currie, Thayne; Egner, Sebastian; Feldt, Markus; Goto, Miwa; Grady, Carol A.; Guyon, Olivier; Hayano, Yutaka; Hayashi, Masahiko; Hayashi, Saeko S.; Hełminiak, Krzysztof G.; Henning, Thomas; Hodapp, Klaus W.; Ida, Shigeru; Ishii, Miki; Itoh, Yoichi; Iye, Masanori; Izumiura, Hideyuki; Janson, Markus; Kambe, Eiji; Kandori, Ryo; Knapp, Gillian R.; Kokubo, Eiichiro; Kwon, Jungmi; Matsuo, Taro; Mayama, Satoshi; McElwain, Michael W.; Mede, Kyle; Miyama, Shoken; Morino, Jun-Ichi; Moro-Martin, Amaya; Nishimura, Tetsuo; Pyo, Tae-Soo; Serabyn, Eugene; Suenaga, Takuya; Suto, Hiroshi; Suzuki, Ryuji; Takami, Michihiro; Takato, Naruhisa; Takeda, Yoichi; Terada, Hiroshi; Thalmann, Christian; Turner, Edwin L.; Watanabe, Makoto; Wisniewski, John; Yamada, Toru; Yoshida, Michitoshi; Takami, Hideki; Usuda, Tomonori; Tamura, Motohide

    2016-07-01

    A radial velocity (RV) survey for intermediate-mass giants has been in operation for over a decade at Okayama Astrophysical Observatory (OAO). The OAO survey has revealed that some giants show long-term linear RV accelerations (RV trends), indicating the presence of outer companions. Direct-imaging observations can help clarify what objects generate these RV trends. We present the results of high-contrast imaging observations of six intermediate-mass giants with long-term RV trends using the Subaru Telescope and HiCIAO camera. We detected co-moving companions to γ Hya B ({0.61}-0.14+0.12{M}⊙ ), HD 5608 B (0.10+/- 0.01{M}⊙ ), and HD 109272 B (0.28+/- 0.06{M}⊙ ). For the remaining targets (ι Dra, 18 Del, and HD 14067), we exclude companions more massive than 30-60 M Jup at projected separations of 1″-7″. We examine whether these directly imaged companions or unidentified long-period companions can account for the RV trends observed around the six giants. We find that the Kozai mechanism can explain the high eccentricity of the inner planets ι Dra b, HD 5608 b, and HD 14067 b.

  1. Radial velocity curve of the spectroscopic binary HD 25639 (ADS 2984A)

    NASA Astrophysics Data System (ADS)

    Gorda, S. Yu.

    2016-10-01

    We present the results of the reduction of our observations for the spectroscopic binary ADS 2984A (B0 II-B0 III), which along with its visual component ADS 2984B (SZ Cam) are the brightest members of the open star cluster NGC 1502. The spectroscopic data were obtained with a fiber-fed echelle spectrograph ( R = 15 000) at the 1.2-m telescope of the Astronomical Observatory of the Ural Federal University. The period of ADS 2984A ( P orb = 57.24 ± 0.05 days) has been found for the first time. This spectroscopic binary is shown to belong to the SB1 type. We have determined the parameters of the radial velocity curve for the visible spectroscopic component, V 0 = -5.5 ± 1.2 km s-1 and K = 41.5 ± 1.7 km s-1. The lower mass limit for the invisible spectroscopic component has been estimated to be 5M_⊙. Evidence for the presence of a stellar wind outflowing from the surface of this blue giant is presented.

  2. SOAP: A Tool for the Fast Computation of Photometry and Radial Velocity Induced by Stellar Spots

    NASA Astrophysics Data System (ADS)

    Boisse, I.; Bonfils, X.; Santos, N. C.; Figueira, P.

    2013-04-01

    Dark spots and bright plages are present on the surface of dwarf stars from spectral types F to M, even in their low-active phase (like the Sun). Their appearance and disappearance on the stellar photosphere, combined with the stellar rotation, may lead to errors and uncertainties in the characterization of planets both in radial velocity (RV) and photometry. Spot Oscillation and Planet (SOAP) is a tool offered to the community that enables to simulate spots and plages on rotating stars and computes their impact on RV and photometric measurements. This tool will help to understand the challenges related to the knowledge of stellar activity for the next decade: detect telluric planets in the habitable zone of their stars (from G to M dwarfs), understand the activity in the low-mass end of M dwarf (on which future projects, like SPIRou or CARMENES, will focus), limitation to the characterization of the exoplanetary atmosphere (from the ground or with Spitzer, JWST), search for planets around young stars. These can be simulated with SOAP in order to search for indices and corrections to the effect of activity.

  3. Sensitivity bias in the mass-radius distribution from transit timing variations and radial velocity measurements

    NASA Astrophysics Data System (ADS)

    Steffen, Jason H.

    2016-04-01

    Motivated by recent discussions, both in private and in the literature, we use a Monte Carlo simulation of planetary systems to investigate sources of bias in determining the mass-radius distribution of exoplanets for the two primary techniques used to measure planetary masses - radial velocities (RVs) and transit timing variations (TTVs). We assert that mass measurements derived from these two methods are comparably reliable - as the physics underlying their respective signals is well understood. Nevertheless, their sensitivity to planet mass varies with the properties of the planets themselves. We find that for a given planet size, the RV method tends to find planets with higher mass while the sensitivity of TTVs is more uniform. This `sensitivity bias' implies that a complete census of TTV systems is likely to yield a more robust estimate of the mass-radius distribution provided there are not important physical differences between planets near and far from mean-motion resonance. We discuss differences in the sensitivity of the two methods with orbital period and system architecture, which may compound the discrepancies between them (e.g. short-period planets detectable by RVs may be more dense due to atmospheric loss). We advocate for continued mass measurements using both approaches as a means both to measure the masses of more planets and to identify potential differences in planet structure that may result from their dynamical and environmental histories.

  4. Asymmetric orbital distribution near mean motion resonance: Application to planets observed by Kepler and radial velocities

    SciTech Connect

    Xie, Ji-Wei E-mail: jwxie@astro.utoronto.ca

    2014-05-10

    Many multiple-planet systems have been found by the Kepler transit survey and various radial velocity (RV) surveys. Kepler planets show an asymmetric feature, namely, there are small but significant deficits/excesses of planet pairs with orbital period spacing slightly narrow/wide of the exact resonance, particularly near the first order mean motion resonance (MMR), such as 2:1 and 3:2 MMR. Similarly, if not exactly the same, an asymmetric feature (pileup wide of 2:1 MMR) is also seen in RV planets, but only for massive ones. We analytically and numerically study planets' orbital evolutions near and in the MMR. We find that their orbital period ratios could be asymmetrically distributed around the MMR center regardless of dissipation. In the case of no dissipation, Kepler planets' asymmetric orbital distribution could be partly reproduced for 3:2 MMR but not for 2:1 MMR, implying that dissipation might be more important to the latter. The pileup of massive RV planets just wide of 2:1 MMR is found to be consistent with the scenario that planets formed separately then migrated toward the MMR. The location of the pileup infers a K value of 1-100 on the order of magnitude for massive planets, where K is the damping rate ratio between orbital eccentricity and semimajor axis during planet migration.

  5. High-contrast Imaging of Intermediate-mass Giants with Long-term Radial Velocity Trends

    NASA Astrophysics Data System (ADS)

    Ryu, Tsuguru; Sato, Bun’ei; Kuzuhara, Masayuki; Narita, Norio; Takahashi, Yasuhiro H.; Uyama, Taichi; Kudo, Tomoyuki; Kusakabe, Nobuhiko; Hashimoto, Jun; Omiya, Masashi; Harakawa, Hiroki; Abe, Lyu; Ando, Hiroyasu; Brandner, Wolfgang; Brandt, Timothy D.; Carson, Joseph C.; Currie, Thayne; Egner, Sebastian; Feldt, Markus; Goto, Miwa; Grady, Carol A.; Guyon, Olivier; Hayano, Yutaka; Hayashi, Masahiko; Hayashi, Saeko S.; Hełminiak, Krzysztof G.; Henning, Thomas; Hodapp, Klaus W.; Ida, Shigeru; Ishii, Miki; Itoh, Yoichi; Iye, Masanori; Izumiura, Hideyuki; Janson, Markus; Kambe, Eiji; Kandori, Ryo; Knapp, Gillian R.; Kokubo, Eiichiro; Kwon, Jungmi; Matsuo, Taro; Mayama, Satoshi; McElwain, Michael W.; Mede, Kyle; Miyama, Shoken; Morino, Jun-Ichi; Moro-Martin, Amaya; Nishimura, Tetsuo; Pyo, Tae-Soo; Serabyn, Eugene; Suenaga, Takuya; Suto, Hiroshi; Suzuki, Ryuji; Takami, Michihiro; Takato, Naruhisa; Takeda, Yoichi; Terada, Hiroshi; Thalmann, Christian; Turner, Edwin L.; Watanabe, Makoto; Wisniewski, John; Yamada, Toru; Yoshida, Michitoshi; Takami, Hideki; Usuda, Tomonori; Tamura, Motohide

    2016-07-01

    A radial velocity (RV) survey for intermediate-mass giants has been in operation for over a decade at Okayama Astrophysical Observatory (OAO). The OAO survey has revealed that some giants show long-term linear RV accelerations (RV trends), indicating the presence of outer companions. Direct-imaging observations can help clarify what objects generate these RV trends. We present the results of high-contrast imaging observations of six intermediate-mass giants with long-term RV trends using the Subaru Telescope and HiCIAO camera. We detected co-moving companions to γ Hya B ({0.61}-0.14+0.12{M}ȯ ), HD 5608 B (0.10+/- 0.01{M}ȯ ), and HD 109272 B (0.28+/- 0.06{M}ȯ ). For the remaining targets (ι Dra, 18 Del, and HD 14067), we exclude companions more massive than 30–60 M Jup at projected separations of 1″–7″. We examine whether these directly imaged companions or unidentified long-period companions can account for the RV trends observed around the six giants. We find that the Kozai mechanism can explain the high eccentricity of the inner planets ι Dra b, HD 5608 b, and HD 14067 b.

  6. THEORY OF DISPERSED FIXED-DELAY INTERFEROMETRY FOR RADIAL VELOCITY EXOPLANET SEARCHES

    SciTech Connect

    Van Eyken, Julian C.; Ge Jian; Mahadevan, Suvrath E-mail: jge@astro.ufl.ed

    2010-07-15

    The dispersed fixed-delay interferometer (DFDI) represents a new instrument concept for high-precision radial velocity (RV) surveys for extrasolar planets. A combination of a Michelson interferometer and a medium-resolution spectrograph, it has the potential for performing multi-object surveys, where most previous RV techniques have been limited to observing only one target at a time. Because of the large sample of extrasolar planets needed to better understand planetary formation, evolution, and prevalence, this new technique represents a logical next step in instrumentation for RV extrasolar planet searches, and has been proven with the single-object Exoplanet Tracker (ET) at Kitt Peak National Observatory, and the multi-object W. M. Keck/MARVELS Exoplanet Tracker at Apache Point Observatory. The development of the ET instruments has necessitated fleshing out a detailed understanding of the physical principles of the DFDI technique. Here we summarize the fundamental theoretical material needed to understand the technique and provide an overview of the physics underlying the instrument's working. We also derive some useful analytical formulae that can be used to estimate the level of various sources of error generic to the technique, such as photon shot noise when using a fiducial reference spectrum, contamination by secondary spectra (e.g., crowded sources, spectroscopic binaries, or moonlight contamination), residual interferometer comb, and reference cross-talk error. Following this, we show that the use of a traditional gas absorption fiducial reference with a DFDI can incur significant systematic errors that must be taken into account at the precision levels required to detect extrasolar planets.

  7. A Spitzer search for transits of radial velocity detected super-Earths

    SciTech Connect

    Kammer, J. A.; Knutson, H. A.; Desert, J.-M.; Howard, A. W.; Laughlin, G. P.; Fortney, J. J.; Deming, D.; Todorov, K. O.; Agol, E.; Burrows, A.; Showman, A. P.; Lewis, N. K.

    2014-02-01

    Unlike hot Jupiters or other gas giants, super-Earths are expected to have a wide variety of compositions, ranging from terrestrial bodies like our own to more gaseous planets like Neptune. Observations of transiting systems, which allow us to directly measure planet masses and radii and constrain atmospheric properties, are key to understanding the compositional diversity of the planets in this mass range. Although Kepler has discovered hundreds of transiting super-Earth candidates over the past 4 yr, the majority of these planets orbit stars that are too far away and too faint to allow for detailed atmospheric characterization and reliable mass estimates. Ground-based transit surveys focus on much brighter stars, but most lack the sensitivity to detect planets in this size range. One way to get around the difficulty of finding these smaller planets in transit is to start by choosing targets that are already known to host super-Earth sized bodies detected using the radial velocity (RV) technique. Here we present results from a Spitzer program to observe six of the most favorable RV-detected super-Earth systems, including HD 1461, HD 7924, HD 156668, HIP 57274, and GJ 876. We find no evidence for transits in any of their 4.5 μm flux light curves, and place limits on the allowed transit depths and corresponding planet radii that rule out even the most dense and iron-rich compositions for these objects. We also observed HD 97658, but the observation window was based on a possible ground-based transit detection that was later ruled out; thus the window did not include the predicted time for the transit detection recently made by the Microvariability and Oscillations of Stars space telescope.

  8. METAL-POOR LITHIUM-RICH GIANTS IN THE RADIAL VELOCITY EXPERIMENT SURVEY

    SciTech Connect

    Ruchti, Gregory R.; Fulbright, Jon P.; Wyse, Rosemary F. G.; Gilmore, Gerard F.; Grebel, Eva K.; Bienayme, Olivier; Siebert, Arnaud; Bland-Hawthorn, Joss; Freeman, Ken C.; Gibson, Brad K.; Munari, Ulisse; Navarro, Julio F.; Parker, Quentin A.; Watson, Fred G.; Reid, Warren; Seabroke, George M.; Siviero, Alessandro; Steinmetz, Matthias; Williams, Mary; Zwitter, Tomaz

    2011-12-20

    We report the discovery of eight lithium-rich field giants found in a high-resolution spectroscopic sample of over 700 metal-poor stars ([Fe/H] < -0.5) selected from the Radial Velocity Experiment survey. The majority of the Li-rich giants in our sample are very metal-poor ([Fe/H] {approx}< -1.9), and have a Li abundance (in the form of {sup 7}Li), A(Li) = log (n(Li)/n(H)) + 12, between 2.30 and 3.63, well above the typical upper red giant branch (RGB) limit, A(Li) < 0.5, while two stars, with A(Li) {approx} 1.7-1.8, show similar lithium abundances to normal giants at the same gravity. We further included two metal-poor, Li-rich globular cluster giants in our sample, namely the previously discovered M3-IV101 and newly discovered (in this work) M68-A96. This comprises the largest sample of metal-poor Li-rich giants to date. We performed a detailed abundance analysis of all stars, finding that the majority of our sample stars have elemental abundances similar to that of Li-normal halo giants. Although the evolutionary phase of each Li-rich giant cannot be definitively determined, the Li-rich phase is likely connected to extra mixing at the RGB bump or early asymptotic giant branch that triggers cool bottom processing in which the bottom of the outer convective envelope is connected to the H-burning shell in the star. The surface of a star becomes Li-enhanced as {sup 7}Be (which burns to {sup 7}Li) is transported to the stellar surface via the Cameron-Fowler mechanism. We discuss and discriminate among several models for the extra mixing that can cause Li production, given the detailed abundances of the Li-rich giants in our sample.

  9. Synthesizing exoplanet demographics from radial velocity and microlensing surveys. I. Methodology

    SciTech Connect

    Clanton, Christian; Gaudi, B. Scott

    2014-08-20

    Motivated by the order of magnitude difference in the frequency of giant planets orbiting M dwarfs inferred by microlensing and radial velocity (RV) surveys, we present a method for comparing the statistical constraints on exoplanet demographics inferred from these methods. We first derive the mapping from the observable parameters of a microlensing-detected planet to those of an analogous planet orbiting an RV-monitored star. Using this mapping, we predict the distribution of RV observables for the planet population inferred from microlensing surveys, taking care to adopt reasonable priors for, and properly marginalize over, the unknown physical parameters of microlensing-detected systems. Finally, we use simple estimates of the detection limits for a fiducial RV survey to predict the number and properties of analogs of the microlensing planet population such an RV survey should detect. We find that RV and microlensing surveys have some overlap, specifically for super-Jupiter mass planets (m{sub p} ≳ 1 M {sub Jup}) with periods between ∼3-10 yr. However, the steeply falling planetary mass function inferred from microlensing implies that, in this region of overlap, RV surveys should infer a much smaller frequency than the overall giant planet frequency (m{sub p} ≳ 0.1 M {sub Jup}) inferred by microlensing. Our analysis demonstrates that it is possible to statistically compare and synthesize data sets from multiple exoplanet detection techniques in order to infer exoplanet demographics over wider regions of parameter space than are accessible to individual methods. In a companion paper, we apply our methodology to several representative microlensing and RV surveys to derive the frequency of planets around M dwarfs with orbits of ≲ 30 yr.

  10. A Spitzer Search for Transits of Radial Velocity Detected Super-Earths

    NASA Astrophysics Data System (ADS)

    Kammer, J. A.; Knutson, H. A.; Howard, A. W.; Laughlin, G. P.; Deming, D.; Todorov, K. O.; Desert, J.-M.; Agol, E.; Burrows, A.; Fortney, J. J.; Showman, A. P.; Lewis, N. K.

    2014-02-01

    Unlike hot Jupiters or other gas giants, super-Earths are expected to have a wide variety of compositions, ranging from terrestrial bodies like our own to more gaseous planets like Neptune. Observations of transiting systems, which allow us to directly measure planet masses and radii and constrain atmospheric properties, are key to understanding the compositional diversity of the planets in this mass range. Although Kepler has discovered hundreds of transiting super-Earth candidates over the past 4 yr, the majority of these planets orbit stars that are too far away and too faint to allow for detailed atmospheric characterization and reliable mass estimates. Ground-based transit surveys focus on much brighter stars, but most lack the sensitivity to detect planets in this size range. One way to get around the difficulty of finding these smaller planets in transit is to start by choosing targets that are already known to host super-Earth sized bodies detected using the radial velocity (RV) technique. Here we present results from a Spitzer program to observe six of the most favorable RV-detected super-Earth systems, including HD 1461, HD 7924, HD 156668, HIP 57274, and GJ 876. We find no evidence for transits in any of their 4.5 μm flux light curves, and place limits on the allowed transit depths and corresponding planet radii that rule out even the most dense and iron-rich compositions for these objects. We also observed HD 97658, but the observation window was based on a possible ground-based transit detection that was later ruled out; thus the window did not include the predicted time for the transit detection recently made by the Microvariability and Oscillations of Stars space telescope.

  11. A NEW MULTI-BAND RADIAL VELOCITY TECHNIQUE FOR DETECTING EXOPLANETS AROUND ACTIVE STARS

    SciTech Connect

    Ma Bo; Ge Jian E-mail: jge@astrto.ufl.edu

    2012-05-10

    The radial velocity (RV) technique is one of the most efficient ways of detecting exoplanets. However, large RV jitters induced by starspots on an active star can inhibit detection of any exoplanet present or even lead to a false positive detection. This paper presents a new multi-band RV technique capable of substantially reducing starspot-induced RV jitters from stellar RV measurements to allow efficient and accurate extraction of RV signals caused by exoplanets. It takes full advantage of the correlation of RV jitters at different spectral bands and the independence of exoplanet signals at the corresponding bands. Simulations with a single-spot model and a multi-spot model have been conducted to investigate the RV jitter reduction capability of this method. The results show that this method can reduce the RV jitter amplitude by at least an order of magnitude, allowing detection of weaker exoplanet signals without significantly increasing RV observation time and cadence. This method can greatly reduce the observation time required to detect Earth-like planets around solar type stars with {approx}0.1 m s{sup -1} long term Doppler precision if spot-induced jitter is the dominant astrophysical noise source for RV measurements. This method can work efficiently for RV jitter removal if: (1) all the spots on a target star have approximately the same temperature during RV observations; (2) the RV jitter amplitude changes with wavelength, i.e., the RV jitter amplitude ratio, {alpha}, between two different spectral bands is not close to one; (3) the spot-induced RV jitter dominates the RV measurement error.

  12. Astrometry, Radial Velocity, and Photometry: The HD 128311 System Remixed with Data from HST, HET, and APT

    NASA Astrophysics Data System (ADS)

    McArthur, Barbara. E.; Benedict, G. Fritz; Henry, Gregory W.; Hatzes, Artie; Cochran, William D.; Harrison, Tom E.; Johns-Krull, Chris; Nelan, Ed

    2014-11-01

    We have used high-cadence radial velocity measurements from the Hobby-Eberly Telescope with published velocities from the Lick 3 m Shane Telescope, combined with astrometric data from the Hubble Space Telescope (HST) Fine Guidance Sensors to refine the orbital parameters of the HD 128311 system, and determine an inclination of 55.°95 ± 14.°55 and true mass of 3.789 +0.924 -0.432 M JUP for HD 128311 c. The combined radial velocity data also reveal a short period signal which could indicate a third planet in the system with an Msin i of 0.133 ± 0.005 M JUP or stellar phenomena. Photometry from the T12 0.8 m automatic photometric telescope at the Fairborn Observatory and HST are used to determine a photometric period close to, but not within the errors of the radial velocity signal. We performed a cross-correlation bisector analysis of the radial velocity data to look for correlations with the photometric period and found none. Dynamical integrations of the proposed system show long-term stability with the new orbital parameters of over 10 million years. Our new orbital elements do not support the claims of HD 128311 b and c being in mean motion resonance. Based on observations made with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555. Based on observations obtained with the Hobby-Eberly Telescope, which is a joint project of the University of Texas at Austin, the Pennsylvania State University, Stanford University, Ludwig-Maximilians-Universität München, and Georg-August-Universität Göttingen, and observations with T12 0.8 m automatic photoelectric telescope (APT) at Fairborn Observatory.

  13. Precise radial velocities of giant stars. VII. Occurrence rate of giant extrasolar planets as a function of mass and metallicity

    NASA Astrophysics Data System (ADS)

    Reffert, Sabine; Bergmann, Christoph; Quirrenbach, Andreas; Trifonov, Trifon; Künstler, Andreas

    2015-02-01

    Context. We have obtained precise radial velocities for a sample of 373 G and K type giants at Lick Observatory regularly over more than 12 years. Planets have been identified around 15 of these giant stars, and an additional 20 giant stars host planet candidates. Aims: We are interested in the occurrence rate of substellar companions around giant stars as a function of stellar mass and metallicity. We probe the stellar mass range from approximately 1 to beyond 3 M⊙, which is not being explored by main-sequence samples. Methods: We fit the giant planet occurrence rate as a function of stellar mass and metallicity with a Gaussian and an exponential distribution, respectively. Results: We find strong evidence for a planet-metallicity correlation among the secure planet hosts of our giant star sample, in agreement with the one for main-sequence stars. However, the planet-metallicity correlation is absent for our sample of planet candidates, raising the suspicion that a good fraction of them might indeed not be planets despite clear periodicities in the radial velocities. Consistent with the literature results for subgiants, the giant planet occurrence rate increases in the stellar mass interval from 1 to 1.9 M⊙. However, there is a maximum at a stellar mass of 1.9+ 0.1-0.5 M⊙, and the occurrence rate drops rapidly for masses larger than 2.5-3.0 M⊙. We do not find any planets around stars more massive than 2.7 M⊙, although there are 113 stars with masses between 2.7 and 5 M⊙ in our sample (corresponding to a giant planet occurrence rate smaller than 1.6% at 68.3% confidence in that stellar mass bin). We also show that this result is not a selection effect related to the planet detectability being a function of the stellar mass. Conclusions: We conclude that giant planet formation or inward migration is suppressed around higher mass stars, possibly because of faster disk depletion coupled with a longer migration timescale. Based on observations collected at

  14. VizieR Online Data Catalog: Radial velocities in 2006-2014 for HD 89758 (Lee+, 2016)

    NASA Astrophysics Data System (ADS)

    Lee, B.-C.; Han, I.; Park, M.-G.; Mkrtichian, D. E.; Hatzes, A. P.; Jeong, G.; Kim, K.-M.

    2016-07-01

    Observations were carried out using the fiber-fed high-resolution Bohyunsan Observatory Echelle Spectrograph (BOES) attached to the 1.8m telescope at Bohyunsan Optical Astronomy Observatory (BOAO) in Korea. One exposure with the BOES has a wavelength coverage 3500-10500Å distributed over ~80 spectral orders. In order to provide precise radial velocity measurements, we used the 80μm diameter fiber which yields a resolving power R=90000. Over the eight-year period from 2006 November to 2014 November (56 nights in total), 112 spectra for μ UMa were collected. The estimated signal-to-noise ratio (S/N) in the I2 region was about 250 with a typical exposure time ranging from 60 to 480s. We report our radial velocity data for μ UMa in Table2. (1 data file).

  15. ARE PROTO-PLANETARY NEBULAE SHAPED BY A BINARY? RESULTS OF A LONG-TERM RADIAL VELOCITY STUDY

    SciTech Connect

    Hrivnak, Bruce J.; Lu Wenxian; Bohlender, David; Morris, S. C.; Woodsworth, Andrew W.; Scarfe, C. D. E-mail: wen.lu@valpo.edu E-mail: David.Bohlender@nrc-cnrc.gc.ca

    2011-06-10

    The shaping of the nebula is currently one of the outstanding unsolved problems in planetary nebula (PN) research. Several mechanisms have been proposed, most of which require a binary companion. However, direct evidence for a binary companion is lacking in most PNs. We have addressed this problem by obtaining precise radial velocities of seven bright proto-planetary nebulae (PPNs), objects in transition from the asymptotic giant branch to the PN phases of stellar evolution. These have F-G spectral types and have the advantage over PNs of having more and sharper spectral lines, leading to better precision. Our observations were made in two observing intervals, 1991-1995 and 2007-2010, and we have included in our analysis some additional published and unpublished data. Only one of the PPNs, IRAS 22272+5435, shows a long-term variation that might tentatively be attributed to a binary companion, with P > 22 yr, and from this, limiting binary parameters are calculated. Selection effects are also discussed. These results set significant restrictions on the range of possible physical and orbital properties of any binary companions: they have periods greater than 25 yr or masses of brown dwarfs or super-Jupiters. While not ruling out the binary hypothesis, it seems fair to say that these results do not support it.

  16. Radial velocities of galaxies in the cluster Klemola 22 from observations with OPTOPUS, the ESO multiple object spectroscopy facility

    NASA Astrophysics Data System (ADS)

    Cristiani, S.; D'Odorico, S.; de Souza, R.; Lund, G.; Quintana, H.

    1987-06-01

    This paper presents the first results obtained with the ESO multiple fiber spectroscopic facility (OPTOPUS). Radial velocities and magnitudes are given for 44 galaxies in the cluster Klemola 22. The average redshift is 16160 km s-1 and the velocity dispersion 742 km s-1. The galaxy Kle 22/17 shows strong emission lines of [O III], with a FWHM of 850 km s-1, and is classified as a type 2 Seyfert. From these observations, the average efficiency of OPTOPUS, including telescope, spectrograph and detector, is computed as 1 detected photoelectron Å-1s-1 for an object of 15 B magnitude.

  17. The disk-halo interface of the Milky Way as observed with the Radial Velocity Experiment (RAVE)

    NASA Astrophysics Data System (ADS)

    Steinmetz, Matthias

    2015-08-01

    The Radial Velocity Experiment (RAVE) is the largest wide-field spectroscopic stellar survey of the Milky Way in the pre-Gaia era. Over the period of 2003-2013, 574,630 spectra for 483,330 stars have been amassed in the Ca triplet region at 8410-8795 Å with resolving power R ~ 7500. Spectral range and resolution are comparable to the RVS unit of the Gaia Satellite. Radial velocities at 2km/s accuracy have been derived as well as stellar parameters and chemical abundances for Mg, Al, Si, Ca, Ti, Fe, and Ni. Furthermore, distances have been derived by combining RAVE data with 2MASS and APASS photometry.RAVE data have been applied to a multitude of questions regarding the dynamical and chemical evolution of the Milky Way. In this presentation I will focus on the interface between the thin and thick disk(s) and the Galactic halo, respectively, presenting data on systematic changes in abundence and alpha enrichment of the respectice stellar population with their kinematical properties (rotation velocity, velocity dispersion) out to distances of several kpc from the Sun. Furthermore, systematic changes in the chemical gradients will be presented. An analysis of high velocity stars reveals that while most have abundance properties typical for halo stars, a few stars have more disk-like chemical abundance pattern indicative of that these stars were formed in the disk but later on ejected into the stellar halo.

  18. PRECISE INFRARED RADIAL VELOCITIES FROM KECK/NIRSPEC AND THE SEARCH FOR YOUNG PLANETS

    SciTech Connect

    Bailey, John I. III; White, Russel J.; Tanner, Angelle M.; Blake, Cullen H.; Charbonneau, Dave; Torres, Guillermo; Barman, Travis S. E-mail: white@chara.gsu.edu

    2012-04-10

    We present a high-precision infrared radial velocity (RV) study of late-type stars using spectra obtained with NIRSPEC at the W. M. Keck Observatory. RV precisions of 50 m s{sup -1} are achieved for old field mid-M dwarfs using telluric features for wavelength calibration. Using this technique, 20 young stars in the {beta} Pic (age {approx} 12 Myr) and TW Hya (age {approx} 8 Myr) Associations were monitored over several years to search for low-mass companions; we also included the chromospherically active field star GJ 873 (EV Lac) in this survey. Based on comparisons with previous optical observations of these young active stars, RV measurements at infrared wavelengths mitigate the RV noise caused by star spots by a factor of {approx}3. Nevertheless, star spot noise is still the dominant source of measurement error for young stars at 2.3 {mu}m, and limits the precision to {approx}77 m s{sup -1} for the slowest rotating stars (v sin i < 6 km s{sup -1}), increasing to {approx}168 m s{sup -1} for rapidly rotating stars (v sin i > 12 km s{sup -1}). The observations reveal both GJ 3305 and TWA 23 to be single-lined spectroscopic binaries; in the case of GJ 3305, the motion is likely caused by its 0.''09 companion, identified after this survey began. The large amplitude, short-timescale variations of TWA 13A are indicative of a hot Jupiter-like companion, but the available data are insufficient to confirm this. We label it as a candidate RV variable. For the remainder of the sample, these observations exclude the presence of any 'hot' (P < 3 days) companions more massive than 8 M{sub Jup} and any 'warm' (P < 30 days) companions more massive than 17 M{sub Jup}, on average. Assuming an edge-on orbit for the edge-on disk system AU Mic, these observations exclude the presence of any hot Jupiters more massive than 1.8 M{sub Jup} or warm Jupiters more massive than 3.9 M{sub Jup}.

  19. Radial velocity information content of M dwarf spectra in the near-infrared

    NASA Astrophysics Data System (ADS)

    Figueira, P.; Adibekyan, V. Zh.; Oshagh, M.; Neal, J. J.; Rojas-Ayala, B.; Lovis, C.; Melo, C.; Pepe, F.; Santos, N. C.; Tsantaki, M.

    2016-02-01

    Aims: We evaluate the radial velocity (RV) information content and achievable precision on M0-M9 spectra covering the ZYJHK bands. We do so while considering both a perfect atmospheric transmission correction and discarding areas polluted by deep telluric features, as done in previous works. Methods: To simulate the M-dwarf spectra, PHOENIX-ACES model spectra were employed; they were convolved with rotational kernels and instrumental profiles to reproduce stars with a v sin i of 1.0, 5.0, and 10.0 km s-1 when observed at resolutions of 60 000, 80 000, and 100 000. We considered the RV precision as calculated on the whole spectra, after discarding strongly polluted areas, and after applying a perfect telluric correction. In the latter option, we took into account the reduction in the number of recorded photons due to a transmittance lower than unity and considered its effect on the noise of the recorded spectra. In our simulations we paid particular attention to the details of the convolution and sampling of the spectra, and we discuss their impact on the final spectra. Results: Our simulations show that the most important parameter ruling the difference in attainable precision between the considered bands is the spectral type. For M0-M3 stars, the bands that deliver the most precise RV measurements are the Z, Y, and H band, with relative merits depending on the parameters of the simulation. For M6-M9 stars, the bands show a difference in precision that is within a factor of ~2 and does not clearly depend on the band; this difference is reduced to a factor smaller than ~1.5 if we consider a non-rotating star seen at high resolution. We also show that an M6-M9 spectrum will deliver a precision about two times better as an M0-M3 spectra with the same signal-to-noise ratio. Finally, we note that the details of modeling the Earth atmosphere and interpreting the results have a significant impact on which wavelength regions are discarded when setting a limit threshold at

  20. Multiplexed High-Precision Radial Velocities: Searching for Hot Jupiters in Southern Open Star Clusters

    NASA Astrophysics Data System (ADS)

    Bailey, John Ira, III

    The Michigan/Magellan Fiber System enables a multiplexed, precision radial velocity (pRV) survey of open star clusters for warm- and hot-Jupiter exoplanetary companions while simultaneously allowing detailed study of stellar properties. To accomplish this, I created an automated control system that enables users to rapidly reconfigure M2FS for different scientific programs and developed a novel mechanism to improve its maximum resolving power from ˜20,000 to ˜60,000. I report the results of a survey of 126 photometric members of the young (141 Myr), nearby (346 pc) open star cluster NGC 2516 and 100 photometric members plus 25 candidate members of the young (72 Myr), nearby (491 pc) open cluster NGC 2422 (M 47). I developed a prescription to spectroscopically measure Teff (+/-30 K), [Fe/H] and [alpha/Fe] (+/-0.02 dex), and vr sin(i) (+/-0.3 km/s). Observations of a reference star show my approach with M2FS can achieve RV precisions of 20¨C60 m/s for up to 128 stars simultaneously. RV measurements enabled memberships lists to be confirmed; 41 claimed members were rejected in NGC 2516 and 52 in NGC 2422. Twelve new members of NGC 2422 are identified, as is a separate RV clustering of 11 giant-like stars in the field of NGC 2422. I propose these giant-like stars are members of a background Milky Way halo stream. I report the discovery of 8 double-lined spectroscopic binaries (SBs) and used pRV measurements spanning 386 days to identify 54 single-lined SBs, 44 of which are new discoveries (16 and 9 as members in NGC 2516 or NGC 2422). I also identify 53 stars which exhibit significant low-amplitude variability after accounting for average levels of stellar jitter. Finally, I identify 8 low-amplitude RV variable stars as candidate hot-Jupiter hosts worth follow-up investigation.

  1. Pulsation in the atmosphere of the roAp star HD 24712. I. Spectroscopic observations and radial velocity measurements

    NASA Astrophysics Data System (ADS)

    Ryabchikova, T.; Sachkov, M.; Weiss, W. W.; Kallinger, T.; Kochukhov, O.; Bagnulo, S.; Ilyin, I.; Landstreet, J. D.; Leone, F.; Lo Curto, G.; Lüftinger, T.; Lyashko, D.; Magazzù, A.

    2007-02-01

    Aims:We have investigated the structure of the pulsating atmosphere of one of the best studied rapidly oscillating Ap stars, HD 24712. Methods: For this purpose we analyzed spectra collected during 2001-2004. An extensive data set was obtained in 2004 simultaneously with the photometry of the Canadian MOST mini-satellite. This allows us to connect directly atmospheric dynamics observed as radial velocity variations with light variations seen in photometry. Results: We directly derived for the first time and for different chemical elements, respectively ions, phase shifts between photometric and radial velocity pulsation maxima indicating, as we suggest, different line formation depths in the atmosphere. This allowed us to estimate for the first time the propagation velocity of a pulsation wave in the outer stellar atmosphere of a roAp star to be slightly lower than the sound speed. We confirm large pulsation amplitudes (150-400 m s-1) for REE lines and the Hα core, while spectral lines of the other elements (Mg, Si, Ca, and Fe-peak elements) have nearly constant velocities. We did not find different pulsation amplitudes and phases for the lines of rare-earth elements before and after the Balmer jump, which supports the hypothesis of REE concentration in the upper atmosphere above the hydrogen line-forming layers. We also discuss radial velocity amplitudes and phases measured for individual spectral lines as tools for a 3D tomography of the atmosphere of HD 24712. Based on observations collected at the Canada-France-Hawaii Telescope (CFHT), at the Nordic Optical Telescope (NOT), at the European Southern Observatory, Paranal, Chile, (DDT-274.D-5011), at the Telescopio Nazionale Galileo (TNG), and from MOST, a Canadian Space Agency mission operated jointly by Dynacon, Inc., the University of Toronto Institute of Aerospace Studies, and the University of British Columbia, with assistance from the University of Vienna. Tables 4, 5 and Fig. 9 are only available in

  2. Catalogues of radial and rotational velocities of 1253 F-K dwarfs in 13 nearby open clusters

    NASA Astrophysics Data System (ADS)

    Mermilliod, J.-C.; Mayor, M.; Udry, S.

    2009-05-01

    Context: We conducted a long-term monitoring of solar-type dwarfs in 13 nearby open clusters, d < 500 pc, over 19 years, but most individual radial velocities were never published, apart from a small number of spectroscopic binaries. Aims: Our program was designed to study membership and duplicity, and to search for new cluster members. Methods: We obtained 6070 radial velocities during 19 years of observations at the Haute-Provence Observatory (France) and 1130 during 13 years at ESO La Silla (Chile) for 1253 stars in the field of 13 open clusters. The zeropoint of the CORAVEL radial velocity system was improved and the new values supersede those published previously. Results: The membership and binarity of solar-type stars in NGC 1976 (Orion), IC 2602, NGC 7092, and NGC 2682 are briefly discussed. For the entire sample, we confirmed the membership of 894 stars and discovered 150 new spectroscopic binaries among them. Added to those already known in the Hyades and Coma Berenices, the number of member spectroscopic binaries is 188. The overall binary frequency is 30% (188/618) for stars with at least 2 measurements. Since no spectroscopic binaries were found among its 26 members, IC 2602 may however represent an exception. New orbital elements were computed with the updated values of the radial velocities for 66 systems, representing 55 members and 11 non-members. Conclusions: This paper is the final report from our team of CORAVEL radial velocities of solar-type dwarfs in nearby open clusters. All CORAVEL observations for dwarfs and red giants in open clusters are now available in electronic form. Based on observations collected at the Haute-Provence Observatory (France) and with the Danish 1.54-m at the European Southern Observatory, La Silla, Chile. This reaserch has made use of the WEBDA database, operated at the Institute for Astronomy of the University of Vienna, and of the SIMBAD database, operated at CDS, Strasbourg, France This publication makes use of

  3. SOAP 2.0: A Tool to Estimate the Photometric and Radial Velocity Variations Induced by Stellar Spots and Plages

    NASA Astrophysics Data System (ADS)

    Dumusque, X.; Boisse, I.; Santos, N. C.

    2014-12-01

    This paper presents SOAP 2.0, a new version of the Spot Oscillation And Planet (SOAP) code that estimates in a simple way the photometric and radial velocity (RV) variations induced by active regions. The inhibition of the convective blueshift (CB) inside active regions is considered, as well as the limb brightening effect of plages, a quadratic limb darkening law, and a realistic spot and plage contrast ratio. SOAP 2.0 shows that the activity-induced variation of plages is dominated by the inhibition of the CB effect. For spots, this effect becomes significant only for slow rotators. In addition, in the case of a major active region dominating the activity-induced signal, the ratio between the FWHM and the RV peak-to-peak amplitudes of the cross correlation function can be used to infer the type of active region responsible for the signal for stars with v sin i <=8 km s-1. A ratio smaller than three implies a spot, while a larger ratio implies a plage. Using the observation of HD 189733, we show that SOAP 2.0 manages to reproduce the activity variation as well as previous simulations when a spot is dominating the activity-induced variation. In addition, SOAP 2.0 also reproduces the activity variation induced by a plage on the slowly rotating star α Cen B, which is not possible using previous simulations. Following these results, SOAP 2.0 can be used to estimate the signal induced by spots and plages, but also to correct for it when a major active region is dominating the RV variation. . The work in this paper is based on observations made with the MOST satellite, the HARPS instrument on the ESO 3.6 m telescope at La Silla Observatory (Chile), and the SOPHIE instrument at the Observatoire de Haute Provence (France).

  4. SOAP 2.0: a tool to estimate the photometric and radial velocity variations induced by stellar spots and plages

    SciTech Connect

    Dumusque, X.; Boisse, I.; Santos, N. C.

    2014-12-01

    This paper presents SOAP 2.0, a new version of the Spot Oscillation And Planet (SOAP) code that estimates in a simple way the photometric and radial velocity (RV) variations induced by active regions. The inhibition of the convective blueshift (CB) inside active regions is considered, as well as the limb brightening effect of plages, a quadratic limb darkening law, and a realistic spot and plage contrast ratio. SOAP 2.0 shows that the activity-induced variation of plages is dominated by the inhibition of the CB effect. For spots, this effect becomes significant only for slow rotators. In addition, in the case of a major active region dominating the activity-induced signal, the ratio between the FWHM and the RV peak-to-peak amplitudes of the cross correlation function can be used to infer the type of active region responsible for the signal for stars with v sin i ≤8 km s{sup –1}. A ratio smaller than three implies a spot, while a larger ratio implies a plage. Using the observation of HD 189733, we show that SOAP 2.0 manages to reproduce the activity variation as well as previous simulations when a spot is dominating the activity-induced variation. In addition, SOAP 2.0 also reproduces the activity variation induced by a plage on the slowly rotating star α Cen B, which is not possible using previous simulations. Following these results, SOAP 2.0 can be used to estimate the signal induced by spots and plages, but also to correct for it when a major active region is dominating the RV variation.

  5. ON THE COMPETITION BETWEEN RADIAL EXPANSION AND COULOMB COLLISIONS IN SHAPING THE ELECTRON VELOCITY DISTRIBUTION FUNCTION: KINETIC SIMULATIONS

    SciTech Connect

    Landi, S.; Matteini, L.; Pantellini, F.

    2012-12-01

    We present numerical simulations of the solar wind using a fully kinetic model which takes into account the effects of particle's binary collisions in a quasi-neutral plasma in spherical expansion. Starting from an isotropic Maxwellian velocity distribution function for the electrons, we show that the combined effect of expansion and Coulomb collisions leads to the formation of two populations: a collision-dominated cold and dense population almost isotropic in velocity space and a weakly collisional, tenuous field-aligned and antisunward drifting population generated by mirror force focusing in the radially decreasing magnetic field. The relative weights and drift velocities for the two populations observed in our simulations are in excellent agreement with the relative weights and drift velocities for both core and strahl populations observed in the real solar wind. The radial evolution of the main moments of the electron velocity distribution function is in the range observed in the solar wind. The electron temperature anisotropy with respect to the magnetic field direction is found to be related to the ratio between the collisional time and the solar wind expansion time. Even though collisions are found to shape the electron velocity distributions and regulate the properties of the strahl, it is found that the heat flux is conveniently described by a collisionless model where a fraction of the electron thermal energy is advected at the solar wind speed. This reinforces the currently largely admitted fact that collisions in the solar wind are clearly insufficient to force the electron heat flux obey the classical Spitzer-Haerm expression where heat flux and temperature gradient are proportional to each other. The presented results show that the electron dynamics in the solar wind cannot be understood without considering the role of collisions.

  6. Characterization of azimuthal and radial velocity fields induced by rotors in flows with a low Reynolds number.

    PubMed

    Köhler, J; Friedrich, J; Ostendorf, A; Gurevich, E L

    2016-02-01

    We theoretically and experimentally investigate the flow field that emerges from a rodlike microrotor rotating about its center in a nonaxisymmetric manner. A simple theoretical model is proposed that uses a superposition of two rotlets as a fundamental solution to the Stokes equation. The predictions of this model are compared to measurements of the azimuthal and radial microfluidic velocity field components that are induced by a rotor composed of fused microscopic spheres. The rotor is driven magnetically and the fluid flow is measured with the help of a probe particle fixed by an optical tweezer. We find considerable deviations of the mere azimuthal flow pattern induced by a single rotating sphere as it has been reported by Di Leonardo et al. [Phys. Rev. Lett. 96, 134502 (2006)]. Notably, the presence of a radial velocity component that manifests itself by an oscillation of the probe particle with twice the rotor frequency is observed. These findings open up a way to discuss possible radial transport in microfluidic devices.

  7. Characterization of azimuthal and radial velocity fields induced by rotors in flows with a low Reynolds number

    NASA Astrophysics Data System (ADS)

    Köhler, J.; Friedrich, J.; Ostendorf, A.; Gurevich, E. L.

    2016-02-01

    We theoretically and experimentally investigate the flow field that emerges from a rodlike microrotor rotating about its center in a nonaxisymmetric manner. A simple theoretical model is proposed that uses a superposition of two rotlets as a fundamental solution to the Stokes equation. The predictions of this model are compared to measurements of the azimuthal and radial microfluidic velocity field components that are induced by a rotor composed of fused microscopic spheres. The rotor is driven magnetically and the fluid flow is measured with the help of a probe particle fixed by an optical tweezer. We find considerable deviations of the mere azimuthal flow pattern induced by a single rotating sphere as it has been reported by Di Leonardo et al. [Phys. Rev. Lett. 96, 134502 (2006), 10.1103/PhysRevLett.96.134502]. Notably, the presence of a radial velocity component that manifests itself by an oscillation of the probe particle with twice the rotor frequency is observed. These findings open up a way to discuss possible radial transport in microfluidic devices.

  8. Flow mechanism of Forchheimer's cubic equation in high-velocity radial gas flow through porous media

    SciTech Connect

    Ezeudembah, A.S.; Dranchuk, P.M.

    1982-01-01

    Formal derivation of Forchheimer's cubic equation is made by considering the kinetic energy equation of mean flow and dimensional relations for one-dimensional, linear, incompressible fluid flow. By the addition of the cubic term, this equation is regarded as a modified Forchheimer's quadratic equation which accounts for the flow rates obtained beyond the laminar flow condition. The cubic equation spans a wide range of flow rates and regimes. For suitable use in gas flow studies, this equation has been adapted, modified, and corrected for the gas slippage effect. The physical basis of the cubic term has been established by using boundary layer theory to explain the high-velocity, high-pressure flow behavior through a porous path. Gamma, the main parameter in the cubic term, is related directly to a characteristic, dimensionless shape factor which is significant at higher flow rates. It is inversely related to viscosity, but has no dependence on the gas slippage coefficient in the higher flow regime. 25 references.

  9. Long-period Variations in the Radial Velocity of Spectroscopic Binary M Giant μ Ursae Majoris

    NASA Astrophysics Data System (ADS)

    Lee, Byeong-Cheol; Han, Inwoo; Park, Myeong-Gu; Mkrtichian, David E.; Hatzes, Artie P.; Jeong, Gwanghui; Kim, Kang-Min

    2016-04-01

    We report that the spectroscopic binary μ Ursae Majoris (μ UMa) has secondary RV variations of 471.2 days in addition to those of 230.0 days already known. Keplerian orbit analysis yields stellar mass companions of 1.6 M⊙ for the 230 day period and 0.14 M⊙ for the 471 day period. However, the HIPPARCOS photometries show a period similar to the stellar rotational period, which is one-quarter of the RV period. Variations in the bisector velocity curvature show a period of 463.6 days. We also find ∼473 day variations in the equivalent width (EW) measurements of the {{{H}}}α and {{{H}}}β lines, whose origin is probably stellar activity. We note that the nature of 471 day variations is similar to one observed in “Sequence D” of Asymptotic Giant Branch pulsating stars. We therefore conclude that the RV and the EW variations in the spectroscopic binary M giant μ UMa A originate from the complex pulsations and the chromospheric activity.

  10. VizieR Online Data Catalog: Radial velocities in seven globular clusters (Lardo+, 2015)

    NASA Astrophysics Data System (ADS)

    Lardo, C.; Pancino, E.; Bellazzini, M.; Bragaglia, A.; Donati, P.; Gilmore, G.; Randich, S.; Feltzing, S.; Jeffries, R. D.; Vallenari, A.; Alfaro, E. J.; Allende Prieto, C.; Flaccomio, E.; Koposov, S. E.; Recio-Blanco, A.; Bergemann, M.; Carraro, G.; Costado, M. T.; Damiani, F.; Hourihane, A.; Jofree, P.; de Laverny, P.; Marconi, G.; Masseron, T.; Morbidelli, L.; Sacco, G. G.; Worley, C. C.

    2014-11-01

    Velocities are given for 1826 stars in the field of the globular clusters NGC 1851, NGC 2808, NGC 4372, NGC 4833, NGC 5927, NGC 6752, and NGC 7078 observed with FLAMES/GIRAFFE@VLT. The table provides the individual identifications, coordinates, V magnitudes, velocities and their associated uncertainties for each star. (2 data files).

  11. METAL ABUNDANCES, RADIAL VELOCITIES, AND OTHER PHYSICAL CHARACTERISTICS FOR THE RR LYRAE STARS IN THE KEPLER FIELD

    SciTech Connect

    Nemec, James M.; Cohen, Judith G.; Sesar, Branimir; Ripepi, Vincenzo; Derekas, Aliz; Moskalik, Pawel; Chadid, Merieme; Bruntt, Hans E-mail: jmn@isr.bc.ca E-mail: bsesar@astro.caltech.edu E-mail: derekas@konkoly.hu E-mail: chadid@marseille.fr

    2013-08-20

    Spectroscopic iron-to-hydrogen ratios, radial velocities, atmospheric parameters, and new photometric analyses are presented for 41 RR Lyrae stars (and one probable high-amplitude {delta} Sct star) located in the field-of-view of the Kepler space telescope. Thirty-seven of the RR Lyrae stars are fundamental-mode pulsators (i.e., RRab stars) of which sixteen exhibit the Blazhko effect. Four of the stars are multiperiodic RRc pulsators oscillating primarily in the first-overtone mode. Spectroscopic [Fe/H] values for the 34 stars for which we were able to derive estimates range from -2.54 {+-} 0.13 (NR Lyr) to -0.05 {+-} 0.13 dex (V784 Cyg), and for the 19 Kepler-field non-Blazhko stars studied by Nemec et al. the abundances agree will with their photometric [Fe/H] values. Four non-Blazhko RR Lyrae stars that they identified as metal-rich (KIC 6100702, V2470 Cyg, V782 Cyg and V784 Cyg) are confirmed as such, and four additional stars (V839 Cyg, KIC 5520878, KIC 8832417, KIC 3868420) are also shown here to be metal-rich. Five of the non-Blazhko RRab stars are found to be more metal-rich than [Fe/H] {approx}-0.9 dex while all of the 16 Blazhko stars are more metal-poor than this value. New P-{phi}{sub 31}{sup s}-[Fe/H] relationships are derived based on {approx}970 days of quasi-continuous high-precision Q0-Q11 long- and short-cadence Kepler photometry. With the exception of some Blazhko stars, the spectroscopic and photometric [Fe/H] values are in good agreement. Several stars with unique photometric characteristics are identified, including a Blazhko variable with the smallest known amplitude and frequency modulations (V838 Cyg)

  12. Metallicities and radial velocities of two stellar clusters located in the outer regions of the Small Magellanic Cloud

    NASA Astrophysics Data System (ADS)

    Gramajo, L. V.; Parisi, M. C.; Clariá, J. J.; Geisler, D.; Vásquez, S.; Da Costa, G.; Grebel, E. K.

    2016-08-01

    We studied near-infrared spectra of red giant stars in two Small Magellanic Cloud (SMC) clusters. We used the Caii lines to measure radial velocities as well as the equivalent widths of these lines to determine metallicity. The two studied clusters (L32 and L38) are projected on the outer regions of the SMC so they are particularly interesting to examine the possible existence of a change of sign in the metallicity gradient in the outer regions, as suggested by a recent study.

  13. Absence of radial velocity variations in MWC 148 during the recent activity of HESS J0632+057

    NASA Astrophysics Data System (ADS)

    Casares, Jorge; Ribo, Marc; Paredes, Josep M.; Herrero, Artemio; Negueruela, Ignacio; Vilardell, Francesc

    2011-03-01

    MWC 148 is a B0pe-type star suspected to be the counterpart of the variable TeV gamma-ray source HESS J0632+057, which also shows variable radio and X-ray emission (Aharonian et al. 2007, A&A, 469, L1; Acciari et al. 2009, ApJ, 698, L94; Hinton et al. 2009, ApJ, 690, L101; Skilton et al. 2009, MNRAS, 399, 317; Falcone et al. 2009, ApJ, 708, L52). MWC 148 is thought to be a gamma-ray binary, although evidence of binarity from radial velocity measurements is still lacking (Aragona et al.

  14. The Göttingen Solar Radial Velocity Project: Sub-m s-1 Doppler Precision from FTS Observations of the Sun as a Star

    NASA Astrophysics Data System (ADS)

    Lemke, U.; Reiners, A.

    2016-09-01

    Radial velocity observations of stars are entering the sub-m s-1 domain revealing fundamental barriers for Doppler precision experiments. Observations of the Sun as a star can easily overcome the m s-1 photon limit but face other obstacles. We introduce the Göttingen Solar Radial Velocity Project with the goal of obtaining high-precision (cm s-1) radial velocity measurements of the Sun as a star with a Fourier Transform Spectrograph. In this first paper, we present the project and first results. The photon limit of our 2 minute observations is at the 2 cm s-1 level but is currently limited by strong instrumental systematics. A drift of a few m s-1 hr-1 is visible in all observing days, probably caused by vignetting of the solar disk in our fiber-coupled setup, and imperfections of our guiding system add further offsets in our data. Binning the data into 30 minute groups shows m s-1 stability after correcting for a daily and linear instrumental trend. Our results show the potential of Sun-as-a-star radial velocity measurements that can possibly be achieved after a substantial upgrade of our spectrograph coupling strategy. Sun-as-a-star observations can provide crucial empirical information about the radial velocity signal of convective motion and stellar activity and on the wavelength dependence of radial velocity signals caused by stellar line profile variations.

  15. The Göttingen Solar Radial Velocity Project: Sub-m s‑1 Doppler Precision from FTS Observations of the Sun as a Star

    NASA Astrophysics Data System (ADS)

    Lemke, U.; Reiners, A.

    2016-09-01

    Radial velocity observations of stars are entering the sub-m s‑1 domain revealing fundamental barriers for Doppler precision experiments. Observations of the Sun as a star can easily overcome the m s‑1 photon limit but face other obstacles. We introduce the Göttingen Solar Radial Velocity Project with the goal of obtaining high-precision (cm s‑1) radial velocity measurements of the Sun as a star with a Fourier Transform Spectrograph. In this first paper, we present the project and first results. The photon limit of our 2 minute observations is at the 2 cm s‑1 level but is currently limited by strong instrumental systematics. A drift of a few m s‑1 hr‑1 is visible in all observing days, probably caused by vignetting of the solar disk in our fiber-coupled setup, and imperfections of our guiding system add further offsets in our data. Binning the data into 30 minute groups shows m s‑1 stability after correcting for a daily and linear instrumental trend. Our results show the potential of Sun-as-a-star radial velocity measurements that can possibly be achieved after a substantial upgrade of our spectrograph coupling strategy. Sun-as-a-star observations can provide crucial empirical information about the radial velocity signal of convective motion and stellar activity and on the wavelength dependence of radial velocity signals caused by stellar line profile variations.

  16. THE M31 VELOCITY VECTOR. II. RADIAL ORBIT TOWARD THE MILKY WAY AND IMPLIED LOCAL GROUP MASS

    SciTech Connect

    Van der Marel, Roeland P.; Sohn, Sangmo Tony; Anderson, Jay; Brown, Tom; Fardal, Mark; Besla, Gurtina; Beaton, Rachael L.; Guhathakurta, Puragra

    2012-07-01

    We determine the velocity vector of M31 with respect to the Milky Way and use this to constrain the mass of the Local Group, based on Hubble Space Telescope proper-motion measurements of three fields presented in Paper I. We construct N-body models for M31 to correct the measurements for the contributions from stellar motions internal to M31. This yields an unbiased estimate for the M31 center-of-mass motion. We also estimate the center-of-mass motion independently, using the kinematics of satellite galaxies of M31 and the Local Group, following previous work but with an expanded satellite sample. All estimates are mutually consistent, and imply a weighted average M31 heliocentric transverse velocity of (v{sub W} , v{sub N} ) = (- 125.2 {+-} 30.8, -73.8 {+-} 28.4) km s{sup -1}. We correct for the reflex motion of the Sun using the most recent insights into the solar motion within the Milky Way, which imply a larger azimuthal velocity than previously believed. This implies a radial velocity of M31 with respect to the Milky Way of V{sub rad,M31} = -109.3 {+-} 4.4 km s{sup -1}, and a tangential velocity of V{sub tan,M31} = 17.0 km s{sup -1}, with a 1{sigma} confidence region of V{sub tan,M31} {<=} 34.3 km s{sup -1}. Hence, the velocity vector of M31 is statistically consistent with a radial (head-on collision) orbit toward the Milky Way. We revise prior estimates for the Local Group timing mass, including corrections for cosmic bias and scatter, and obtain M{sub LG} {identical_to} M{sub MW,vir} + M{sub M31,vir} = (4.93 {+-} 1.63) Multiplication-Sign 10{sup 12} M{sub Sun }. Summing known estimates for the individual masses of M31 and the Milky Way obtained from other dynamical methods yields smaller uncertainties. Bayesian combination of the different estimates demonstrates that the timing argument has too much (cosmic) scatter to help much in reducing uncertainties on the Local Group mass, but its inclusion does tend to increase other estimates by {approx}10%. We

  17. Bayesian analysis of exoplanet and binary orbits. Demonstrated using astrometric and radial-velocity data of Mizar A

    NASA Astrophysics Data System (ADS)

    Schulze-Hartung, T.; Launhardt, R.; Henning, T.

    2012-09-01

    Aims: We introduce BASE (Bayesian astrometric and spectroscopic exoplanet detection and characterisation tool), a novel program for the combined or separate Bayesian analysis of astrometric and radial-velocity measurements of potential exoplanet hosts and binary stars. The capabilities of BASE are demonstrated using all publicly available data of the binary Mizar A. Methods: With the Bayesian approach to data analysis we can incorporate prior knowledge and draw extensive posterior inferences about model parameters and derived quantities. This was implemented in BASE by Markov chain Monte Carlo (MCMC) sampling, using a combination of the Metropolis-Hastings, hit-and-run, and parallel-tempering algorithms to explore the whole parameter space. Nonconvergence to the posterior was tested by means of the Gelman-Rubin statistic (potential scale reduction). The samples were used directly and transformed into marginal densities by means of kernel density estimation, a "smooth" alternative to histograms. We derived the relevant observable models from Newton's law of gravitation, showing that the motion of Earth and the target can be neglected. Results: With our methods we can provide more detailed information about the parameters than a frequentist analysis does. Still, a comparison with the Mizar A literature shows that both approaches are compatible within the uncertainties. Conclusions: We show that the Bayesian approach to inference has been implemented successfully in BASE, a flexible tool for analysing astrometric and radial-velocity data. BASE, the computer program introduced in this article, can be downloaded at http://www.mpia.de/homes/schulze/base.html.

  18. Asteroseismology of the nearby SN-II Progenitor: Rigel. I. The MOST High-precision Photometry and Radial Velocity Monitoring

    NASA Astrophysics Data System (ADS)

    Moravveji, Ehsan; Guinan, Edward F.; Shultz, Matt; Williamson, Michael H.; Moya, Andres

    2012-03-01

    Rigel (β Ori, B8 Ia) is a nearby blue supergiant displaying α Cyg type variability, and is one of the nearest Type II supernova progenitors. As such it is an excellent test bed to study the internal structure of pre-core-collapse stars. In this study, for the first time, we present 28 days of high-precision MOST photometry and over six years of spectroscopic monitoring. We report 19 significant pulsation modes of signal-to-noise ratio, S/N >~ 4.6 from radial velocities, with variability timescales ranging from 1.21 to 74.7 days, which are associated with high-order low-degree gravity modes. While the radial velocity variations show a degree of correlation with the flux changes, there is no clear interplay between the equivalent widths of different metallic and Hα lines. Based on data from the MOST satellite, a Canadian Space Agency mission, operated jointly by Dynacon, Inc., the University of Toronto Institute of Aerospace Studies, and the University of British Columbia, with the assistance of the University of Vienna.

  19. VizieR Online Data Catalog: Radial velocities in M67. I. 1278 candidate members (Geller+, 2015)

    NASA Astrophysics Data System (ADS)

    Geller, A. M.; Latham, D. W.; Mathieu, R. D.

    2015-10-01

    This is the first in a series of papers studying the dynamical state of the old open cluster M67 through precise radial velocities. This is also the paper LXVII of the WIYN Open Cluster Study. Our radial velocity survey of M67 began as part of the dissertation work of Mathieu (1983PhDT.........8M), taking advantage of the CfA Digital Speedometers (DS). Three nearly identical instruments were used, initially on the MMT (from HJD2445337 to HJD2450830) and 1.5m Tillinghast Reflector (from HJD2444184 to HJD2454958) at the Fred Lawrence Whipple Observatory on Mount Hopins, Arizona, and then later on the 1.5m Wyeth Reflector (from HJD2445722 to HJD2453433) at the Oak Ridge Observatory in the Town of Harvard, Massachusetts. Subsequently the M67 target samples were expanded several times. Radial velocities measurements from other programs were integrated into the database, and our observational facilities were extended to include Hydra Multi-Object Spectrograph (MOS) at the WIYN Observatory (from HJD2453386 to HJD2456709) and the new Tillinghast Reflector Echelle Spectrograph (TRES) on the Tillinghast Reflector (from HJD2455143 to HJD2456801). Details about the telescopes, observing procedures, and data reductions of spectra obtained with the CfA DS can be found in Latham (1985srv..conf...21L, 1992ASPC...32..110L). The corresponding information for spectra obtained with Hydra at the WIYN Observatory can be found in Geller et al. 2008 (cat. J/AJ/135/2264), Geller et al. 2010 (cat. J/AJ/139/1383) and Hole et al. (2009). TRES is a stabilized fiber-fed echelle spectrograph with a CCD detector and resolution of 44000. The initial CfA sample was defined in 1982. The last surviving CfA Digital Speedometer, on the 1.5m Tillinghast Reflector, was retired in the summer of 2009. Over the following five observing seasons, TRES was used to continue the radial velocity observations of targets (mostly binaries) from both the CfA and the WIYN samples. Importantly, Roger Griffin and James

  20. Data reduction, radial velocities and stellar parameters from spectra in the very low signal-to-noise domain

    NASA Astrophysics Data System (ADS)

    Malavolta, Luca

    2013-10-01

    Large astronomical facilities usually provide data reduction pipeline designed to deliver ready-to-use scientific data, and too often as- tronomers are relying on this to avoid the most difficult part of an astronomer job Standard data reduction pipelines however are usu- ally designed and tested to have good performance on data with av- erage Signal to Noise Ratio (SNR) data, and the issues that are related with the reduction of data in the very low SNR domain are not taken int account properly. As a result, informations in data with low SNR are not optimally exploited. During the last decade our group has collected thousands of spec- tra using the GIRAFFE spectrograph at Very Large Telescope (Chile) of the European Southern Observatory (ESO) to determine the ge- ometrical distance and dynamical state of several Galactic Globular Clusters but ultimately the analysis has been hampered by system- atics in data reduction, calibration and radial velocity measurements. Moreover these data has never been exploited to get other informa- tions like temperature and metallicity of stars, because considered too noisy for these kind of analyses. In this thesis we focus our attention on data reduction and analysis of spectra with very low SNR. The dataset we analyze in this thesis comprises 7250 spectra for 2771 stars of the Globular Cluster M 4 (NGC 6121) in the wavelength region 5145-5360Å obtained with GIRAFFE. Stars from the upper Red Giant Branch down to the Main Sequence have been observed in very different conditions, including nights close to full moon, and reaching SNR - 10 for many spectra in the dataset. We will first review the basic steps of data reduction and spec- tral extraction, adapting techniques well tested in other field (like photometry) but still under-developed in spectroscopy. We improve the wavelength dispersion solution and the correction of radial veloc- ity shift between day-time calibrations and science observations by following a completely

  1. VizieR Online Data Catalog: M4 Core Project with HST. Radial velocities (Malavolta+, 2015)

    NASA Astrophysics Data System (ADS)

    Malavolta, L.; Piotto, G.; Bedin, L. R.; Sneden, C.; Nascimbeni, V.; Sommariva, V.

    2016-07-01

    The spectra for our project were originally used by Sommariva et al. (2009A&A...493..947S) to study the internal velocity dispersion of M4 and to search for spectroscopic binaries. A total of 2771 stars covering colour-magnitude diagram (CMD) positions from the upper RGB to about 1mag fainter than the main-sequence turnoff (TO) luminosity were observed between 2003 and 2009, including 306 new spectra obtained in 2009 and targeting MS stars already observed in the previous epochs. Determination of the M 4 velocity dispersion and binary star fraction were the prime motivators for obtaining these data. Therefore nearly all stars were observed at least twice, and three or more spectra were obtained for nearly 40 per cent of the sample. (2 data files).

  2. Effects of radial and circumferential inlet velocity profile distortions on performance of a short-length double-annular ram induction combustor

    NASA Technical Reports Server (NTRS)

    Schultz, D. F.; Perkins, P. J.

    1972-01-01

    Inlet air velocity profile tests were conducted on a full-scale short-length 102-centimeter-diameter annual combustor designed for advanced gas turbine engine applications. The inlet profiles studied include radial distortions that were center peaked, and tip peaked, as well as a circumferential distortion which was center peaked for one-third of the circumference and flat for the other two-thirds. An increase in combustor pressure loss was the most significant effect of the radial air velocity distortions. With the circumferential distortion, exit temperature pattern factor doubled when compared to a flat velocity profile.

  3. BANYAN. III. Radial velocity, rotation, and X-ray emission of low-mass star candidates in nearby young kinematic groups

    SciTech Connect

    Malo, Lison; Artigau, Étienne; Doyon, René; Lafrenière, David; Albert, Loïc; Gagné, Jonathan E-mail: doyon@astro.umontreal.ca

    2014-06-10

    Based on high-resolution spectra obtained with PHOENIX at Gemini-South, CRIRES at VLT-UT1, and ESPaDOnS at the Canada-France-Hawaii Telescope, we present new measurements of the radial and projected rotational velocities of 219 low-mass stars. The target likely membership was initially established using the Bayesian analysis tool recently presented in Malo et al., taking into account only the position, proper motion, and photometry of the stars to assess their membership probability. In the present study, we include radial velocity as an additional input to our analysis, and in doing so we confirm the high membership probability for 130 candidates: 27 in β Pictoris, 22 in Tucana-Horologium, 25 in Columba, 7 in Carina, 18 in Argus and 18 in AB Doradus, and 13 with an ambiguous membership. Our analysis also confirms the membership of 57 stars proposed in the literature. A subsample of 16 candidates was observed at 3 or more epochs, allowing us to discover 6 new spectroscopic binaries. The fraction of binaries in our sample is 25%, consistent with values in the literature. Of the stars in our sample, 20% show projected rotational velocities (vsin i) higher than 30 km s{sup –1} and therefore are considered as fast rotators. A parallax and other youth indicators are still needed to fully confirm the 130 highly probable candidates identified here as new bona fide members. Finally, based on the X-ray emission of bona fide and highly probable group members, we show that for low-mass stars in the 12-120 Myr age range, the X-ray luminosity is an excellent indicator of youth and better than the more traditionally used R {sub X} parameter, the ratio of X-ray to bolometric luminosity.

  4. Predicted space motions for hypervelocity and runaway stars: proper motions and radial velocities for the Gaia Era

    SciTech Connect

    Kenyon, Scott J.; Brown, Warren R.; Geller, Margaret J.; Bromley, Benjamin C. E-mail: wbrown@cfa.harvard.edu E-mail: bromley@physics.utah.edu

    2014-10-01

    We predict the distinctive three-dimensional space motions of hypervelocity stars (HVSs) and runaway stars moving in a realistic Galactic potential. For nearby stars with distances less than 10 kpc, unbound stars are rare; proper motions alone rarely isolate bound HVSs and runaways from indigenous halo stars. At large distances of 20-100 kpc, unbound HVSs are much more common than runaways; radial velocities easily distinguish both from indigenous halo stars. Comparisons of the predictions with existing observations are encouraging. Although the models fail to match observations of solar-type HVS candidates from SEGUE, they agree well with data for B-type HVS and runaways from other surveys. Complete samples of g ≲ 20 stars with Gaia should provide clear tests of formation models for HVSs and runaways and will enable accurate probes of the shape of the Galactic potential.

  5. “MODAL NOISE” IN SINGLE-MODE FIBERS: A CAUTIONARY NOTE FOR HIGH PRECISION RADIAL VELOCITY INSTRUMENTS

    SciTech Connect

    Halverson, Samuel; Roy, Arpita; Mahadevan, Suvrath; Schwab, Christian

    2015-12-01

    Exploring the use of single-mode fibers (SMFs) in high precision Doppler spectrometers has become increasingly attractive since the advent of diffraction-limited adaptive optics systems on large-aperture telescopes. Spectrometers fed with these fibers can be made significantly smaller than typical “seeing-limited” instruments, greatly reducing cost and overall complexity. Importantly, classical mode interference and speckle issues associated with multi-mode fibers, also known as “modal noise,” are mitigated when using SMFs, which also provide perfect radial and azimuthal image scrambling. However, SMFs do support multiple polarization modes, an issue that is generally ignored for larger-core fibers given the large number of propagation modes. Since diffraction gratings used in most high resolution astronomical instruments have dispersive properties that are sensitive to incident polarization changes, any birefringence variations in the fiber can cause variations in the efficiency profile, degrading illumination stability. Here we present a cautionary note outlining how the polarization properties of SMFs can affect the radial velocity (RV) measurement precision of high resolution spectrographs. This work is immediately relevant to the rapidly expanding field of diffraction-limited, extreme precision RV spectrographs that are currently being designed and built by a number of groups.

  6. Radial velocities with CRIRES. Pushing precision down to 5-10 m/s

    NASA Astrophysics Data System (ADS)

    Figueira, P.; Pepe, F.; Melo, C. H. F.; Santos, N. C.; Lovis, C.; Mayor, M.; Queloz, D.; Smette, A.; Udry, S.

    2010-02-01

    With the advent of high-resolution infrared spectrographs, radial relocity (RV) searches enter into a new domain. As of today, the most important technical question to address is which wavelength reference is the most suitable for high-precision RV measurements. In this work we use atmospheric absorption features as wavelength reference on CRIRES data obtained on two programs and three different targets. We analyzed the data from the TW Hya campaign again, reaching a dispersion of about 6 m/s on the RV standard on a time scale of roughly 1 week. We confirm that there is a low-amplitude RV signal on TW Hya itself, with an amplitude roughly 3 times smaller than the one reported at visible wavelengths. We present RV measurements of Gl 86 as well, showing that our approach is capable of detecting the signal induced by a planet and correctly quantifying it. Our data show that CRIRES is capable of reaching an RV precision of less than 10 m/s on a time scale of one week. The limitations of this particular approach are discussed, along with the limiting factors on RV precision in the IR in a general way. The implications of this work on the design of future dedicated IR spectrographs are addressed as well. Based on observations taken at the VLT (Paranal), under programs 280.C-5064(A) and 60.A-9051(A), and with the CORALIE spectrograph at the Euler Swiss telescope (La Silla). Tables 2 and 3 are only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/511/A55

  7. RADIAL VELOCITY PLANETS DE-ALIASED: A NEW, SHORT PERIOD FOR SUPER-EARTH 55 Cnc e

    SciTech Connect

    Dawson, Rebekah I.; Fabrycky, Daniel C. E-mail: daniel.fabrycky@gmail.co

    2010-10-10

    Radial velocity measurements of stellar reflex motion have revealed many extrasolar planets, but gaps in the observations produce aliases, spurious frequencies that are frequently confused with the planets' orbital frequencies. In the case of Gl 581 d, the distinction between an alias and the true frequency was the distinction between a frozen, dead planet and a planet possibly hospitable to life. To improve the characterization of planetary systems, we describe how aliases originate and present a new approach for distinguishing between orbital frequencies and their aliases. Our approach harnesses features in the spectral window function to compare the amplitude and phase of predicted aliases with peaks present in the data. We apply it to confirm prior alias distinctions for the planets GJ 876 d and HD 75898 b. We find that the true periods of Gl 581 d and HD 73526 b/c remain ambiguous. We revise the periods of HD 156668 b and 55 Cnc e, which were afflicted by daily aliases. For HD 156668 b, the correct period is 1.2699 days and the minimum mass is (3.1 {+-} 0.4) M{sub +}. For 55 Cnc e, the correct period is 0.7365 days-the shortest of any known planet-and the minimum mass is (8.3 {+-} 0.3) M{sub +}. This revision produces a significantly improved five-planet Keplerian fit for 55 Cnc, and a self-consistent dynamical fit describes the data just as well. As radial velocity techniques push to ever-smaller planets, often found in systems of multiple planets, distinguishing true periods from aliases will become increasingly important.

  8. An Economical High Resolution Spectrograph Optimized for Radial Velocity Measurements at 5000 Angstroms.

    NASA Astrophysics Data System (ADS)

    Lyons, D.; Arion, D. N.

    2004-12-01

    A high resolution spectrometer was built and calibrated on an optical bench. The target resolution of the instrument was designed to allow accurate measurement of the Doppler shifts of the 5007 Angstrom O III line in planetary nebulae due to their expansion. The optical components of the instrument include two Meade ETX 90 Maksutov-Cassegrain telescopes, a Richardson Grating Laboratory reflection diffraction grating, nickel-plated glass slides used as slit apertures, and an SBIG ST-8E CCD imaging camera. The mounts for each of the optical components were machined out of aluminum bar and plate stock. The instrument was calibrated using He and Hg gas discharge tubes generating spectra of known wavelengths. A total of four sets of lines were imaged and analyzed to calibrate the instrument. The line shapes in the images were manually fit with functions approximating the pressure and Doppler broadening of the lines, as expected for the behavior of the lines emitted by the spectrum tubes. These fits were used to identify the line peak positions, which were then compared to standard line wavelengths to determine the instrument calibration. The He I line at 5015.678 Angstrom line was carefully analyzed to determine the system wavelength uncertainty, which determines the smallest resolvable difference in wavelength that the instrument can determine. The resulting operating resolution at 5007 Angstroms was found to be 206474, making the instrument capable of resolving Doppler shifts at 5007 Angstroms corresponding to +/- 1.4 kilometers per second. The program was thus successful in developing an instrument suitable for a variety of relatively low velocity Doppler measurements, especially those associated with planetary nebula expansions. Future work entails developing a mounting system to rigidly hold the instrument on a suitable telescope, while maintaining the necessary precision to retain the instrumental resolution. This work was supported in part by Carthage College

  9. Radial velocity observations of the 2015 Mar. 20 eclipse. A benchmark Rossiter-McLaughlin curve with zero free parameters

    NASA Astrophysics Data System (ADS)

    Reiners, A.; Lemke, U.; Bauer, F.; Beeck, B.; Huke, P.

    2016-10-01

    Spectroscopic observations of a solar eclipse can provide unique information for solar and exoplanet research; the huge amplitude of the Rossiter-McLaughlin (RM) effect during solar eclipse and the high precision of solar radial velocities (RVs) allow detailed comparison between observations and RV models, and they provide information about the solar surface and about spectral line formation that are otherwise difficult to obtain. On March 20, 2015, we obtained 159 spectra of the Sun as a star with the solar telescope and the Fourier Transform Spectrograph at the Institut für Astrophysik Göttingen, 76 spectra were taken during partial solar eclipse. We obtained RVs using I2 as wavelength reference and determined the RM curve with a peak-to-peak amplitude of almost 1.4 km s-1 at typical RV precision better than 1 m s-1. We modeled the disk-integrated solar RVs using well-determined parameterizations of solar surface velocities, limb darkening, and information about convective blueshift from 3D magnetohydrodynamic simulations. We confirm that convective blueshift is crucial to understand solar RVs during eclipse. Our best model reproduced the observations to within a relative precision of 10% with residuals lower than 30 m s-1. We cross-checked parameterizations of velocity fields using a Dopplergram from the Solar Dynamics Observatory and conclude that disk-integration of the Dopplergram does not provide correct information about convective blueshift necessary for m s-1 RV work. As main limitation for modeling RVs during eclipses, we identified limited knowledge about convective blueshift and line shape as functions of solar limb angle. We suspect that our model line profiles are too shallow at limb angles larger than μ = 0.6, resulting in incorrect weighting of the velocities across the solar disk. Alternative explanations cannot be excluded, such as suppression of convection in magnetic areas and undiscovered systematics during eclipse observations. To make

  10. Distribution of Peculiar Radial Velocities in Galactic Clusters in a Model with Dissipative Redshift

    NASA Astrophysics Data System (ADS)

    Orlov, V. V.; Raikov, A. A.

    2016-09-01

    A cosmological model with dissipative redshift is analyzed. In this model the observed redshifts of galaxies in groups and clusters consist of a Doppler part and an additional (dissipative) term associated with differences in photon path lengths. The contribution to the redshifts from dissipation is estimated for models of galactic clusters with parameters similar to the observed characteristics of the Virgo and Coma clusters. It is shown that for these models the dissipative contribution is several times smaller than the contribution from the Doppler effect. Nevertheless, the effect is detectable when reliable, redshift independent estimates of the distances to probable members of galactic clusters are available and may serve as an independent test of the nature of the redshift of lines in the spectra of extragalactic objects.

  11. The Sun as a planet-host star: proxies from SDO images for HARPS radial-velocity variations

    NASA Astrophysics Data System (ADS)

    Haywood, R. D.; Collier Cameron, A.; Unruh, Y. C.; Lovis, C.; Lanza, A. F.; Llama, J.; Deleuil, M.; Fares, R.; Gillon, M.; Moutou, C.; Pepe, F.; Pollacco, D.; Queloz, D.; Ségransan, D.

    2016-04-01

    The Sun is the only star whose surface can be directly resolved at high resolution, and therefore constitutes an excellent test case to explore the physical origin of stellar radial-velocity (RV) variability. We present HARPS observations of sunlight scattered off the bright asteroid 4/Vesta, from which we deduced the Sun's activity-driven RV variations. In parallel, the Helioseismic and Magnetic Imager instrument on board the Solar Dynamics Observatory provided us with simultaneous high spatial resolution magnetograms, Dopplergrams and continuum images of the Sun in the Fe I 6173 Å line. We determine the RV modulation arising from the suppression of granular blueshift in magnetized regions and the flux imbalance induced by dark spots and bright faculae. The rms velocity amplitudes of these contributions are 2.40 and 0.41 m s-1, respectively, which confirms that the inhibition of convection is the dominant source of activity-induced RV variations at play, in accordance with previous studies. We find the Doppler imbalances of spot and plage regions to be only weakly anticorrelated. Light curves can thus only give incomplete predictions of convective blueshift suppression. We must instead seek proxies that track the plage coverage on the visible stellar hemisphere directly. The chromospheric flux index R^' }_{HK} derived from the HARPS spectra performs poorly in this respect, possibly because of the differences in limb brightening/darkening in the chromosphere and photosphere. We also find that the activity-driven RV variations of the Sun are strongly correlated with its full-disc magnetic flux density, which may become a useful proxy for activity-related RV noise.

  12. Finding binaries from phase modulation of pulsating stars with Kepler - IV. Detection limits and radial velocity verification

    NASA Astrophysics Data System (ADS)

    Murphy, Simon J.; Shibahashi, Hiromoto; Bedding, Timothy R.

    2016-10-01

    We explore the detection limits of the phase modulation (PM) method of finding binary systems among multiperiodic pulsating stars. The method is an attractive way of finding non-transiting planets in the habitable zones of intermediate-mass stars, whose rapid rotation inhibits detections via the radial velocity (RV) method. While oscillation amplitudes of a few mmag are required to find planets, many δ Scuti stars have these amplitudes. In suboptimal cases where the signal to noise of the oscillations is lower, low-mass brown dwarfs (˜13MJup) are detectable at orbital periods longer than about 1 yr, and the lowest mass main-sequence stars (0.1-0.2 M⊙) are detectable at all orbital periods where the PM method can be applied. We use purpose-written Markov chain Monte Carlo (MCMC) software for the calculation of the PM orbits, which offers robust uncertainties for comparison with RV solutions. Using Kepler data and ground-based RVs, we verify that these two methods are in agreement, even at short orbital periods where the PM method undersamples the orbit. We develop new theory to account for the undersampling of the time delays, which is also necessary for the inclusion of RVs as observational data in the MCMC software. We show that combining RVs with time delays substantially refines the orbits because of the complementarity of working in both the spatial (PM) and velocity (RV) domains simultaneously. Software outputs were tested through an extensive hare-and-hounds exercise, covering a wide range of orbital configurations including binaries containing two pulsators.

  13. SEVEN NEW BINARIES DISCOVERED IN THE KEPLER LIGHT CURVES THROUGH THE BEER METHOD CONFIRMED BY RADIAL-VELOCITY OBSERVATIONS

    SciTech Connect

    Faigler, S.; Mazeh, T.; Tal-Or, L.; Quinn, S. N.; Latham, D. W.

    2012-02-20

    We present seven newly discovered non-eclipsing short-period binary systems with low-mass companions, identified by the recently introduced BEER algorithm, applied to the publicly available 138-day photometric light curves obtained by the Kepler mission. The detection is based on the beaming effect (sometimes called Doppler boosting), which increases (decreases) the brightness of any light source approaching (receding from) the observer, enabling a prediction of the stellar Doppler radial-velocity (RV) modulation from its precise photometry. The BEER algorithm identifies the BEaming periodic modulation, with a combination of the well-known Ellipsoidal and Reflection/heating periodic effects, induced by short-period companions. The seven detections were confirmed by spectroscopic RV follow-up observations, indicating minimum secondary masses in the range 0.07-0.4 M{sub Sun }. The binaries discovered establish for the first time the feasibility of the BEER algorithm as a new detection method for short-period non-eclipsing binaries, with the potential to detect in the near future non-transiting brown-dwarf secondaries, or even massive planets.

  14. The Habitable-zone Planet Finder (HPF): Achieving high precision radial velocities and mitigating stellar activity noise

    NASA Astrophysics Data System (ADS)

    Mahadevan, Suvrath; Ramsey, Lawrence W.; Terrien, Ryan; Robertson, Paul; Marchwinski, Robert C.; Hearty, Fred; Levi, Eric; Kári Stefánsson, Gudmundur; Bender, Chad F.; Halverson, Samuel; Roy, Arpita; Nelson, Matt; Schwab, Christian

    2015-01-01

    HPF is a stabilized, fiber-fed, near infrared (NIR) spectrograph currently being built at Penn State for the 10m Hobby-Eberly Telescope (HET). HPF will be capable of discovering low mass planets in the Habitable Zones of mid-late M dwarfs via radial velocity (RV). We discuss the development of critical sub-systems like our high-stability temperature control system, vacuum cryostat, and implementation of new wavelength calibration techniques. The design of the HET enables queue-scheduled operation, but its variable pupil requires attention to both near- and far-field fiber scrambling, which we accomplish with double scramblers and octagonal fibers.HPF will provide partial bandwith coverage of the information-rich z, Y and J NIR bands at a spectral resolving power of R˜50,000. While stellar activity induced RV noise is lower in the NIR than at visible wavelengths, we have carefully included NIR activity indicators in our spectral bandpass to help discriminate stellar activity from real planet signals, as has been recently demonstrated for Gliese 581 and Gliese 667C systems.

  15. A laser frequency comb that enables radial velocity measurements with a precision of 1 cm s(-1).

    PubMed

    Li, Chih-Hao; Benedick, Andrew J; Fendel, Peter; Glenday, Alexander G; Kärtner, Franz X; Phillips, David F; Sasselov, Dimitar; Szentgyorgyi, Andrew; Walsworth, Ronald L

    2008-04-01

    Searches for extrasolar planets using the periodic Doppler shift of stellar spectral lines have recently achieved a precision of 60 cm s(-1) (ref. 1), which is sufficient to find a 5-Earth-mass planet in a Mercury-like orbit around a Sun-like star. To find a 1-Earth-mass planet in an Earth-like orbit, a precision of approximately 5 cm s(-1) is necessary. The combination of a laser frequency comb with a Fabry-Pérot filtering cavity has been suggested as a promising approach to achieve such Doppler shift resolution via improved spectrograph wavelength calibration, with recent encouraging results. Here we report the fabrication of such a filtered laser comb with up to 40-GHz (approximately 1-A) line spacing, generated from a 1-GHz repetition-rate source, without compromising long-term stability, reproducibility or spectral resolution. This wide-line-spacing comb, or 'astro-comb', is well matched to the resolving power of high-resolution astrophysical spectrographs. The astro-comb should allow a precision as high as 1 cm s(-1) in astronomical radial velocity measurements. PMID:18385734

  16. On the potential of transit surveys in star clusters: impact of correlated noise and radial velocity follow-up

    NASA Astrophysics Data System (ADS)

    Aigrain, Suzanne; Pont, Frédéric

    2007-06-01

    We present an extension of the formalism recently proposed by Pepper and Gaudi to evaluate the yield of transit surveys in homogeneous stellar systems, incorporating the impact of correlated noise on transit time-scales on the detectability of transits, and simultaneously incorporating the magnitude limits imposed by the need for radial velocity (RV) follow-up of transit candidates. New expressions are derived for the different contributions to the noise budget on transit time-scales and the least-squares detection statistic for box-shaped transits, and their behaviour as a function of stellar mass is re-examined. Correlated noise that is constant with apparent stellar magnitude implies a steep decrease in detection probability at the high-mass end which, when considered jointly with the RV requirements, can severely limit the potential of otherwise promising surveys in star clusters. However, we find that small-aperture, wide-field surveys may detect hot Neptunes whose RV signal can be measured with present-day instrumentation in very nearby (<100pc) clusters.

  17. Seven New Binaries Discovered in the Kepler Light Curves through the BEER Method Confirmed by Radial-velocity Observations

    NASA Astrophysics Data System (ADS)

    Faigler, S.; Mazeh, T.; Quinn, S. N.; Latham, D. W.; Tal-Or, L.

    2012-02-01

    We present seven newly discovered non-eclipsing short-period binary systems with low-mass companions, identified by the recently introduced BEER algorithm, applied to the publicly available 138-day photometric light curves obtained by the Kepler mission. The detection is based on the beaming effect (sometimes called Doppler boosting), which increases (decreases) the brightness of any light source approaching (receding from) the observer, enabling a prediction of the stellar Doppler radial-velocity (RV) modulation from its precise photometry. The BEER algorithm identifies the BEaming periodic modulation, with a combination of the well-known Ellipsoidal and Reflection/heating periodic effects, induced by short-period companions. The seven detections were confirmed by spectroscopic RV follow-up observations, indicating minimum secondary masses in the range 0.07-0.4 M ⊙. The binaries discovered establish for the first time the feasibility of the BEER algorithm as a new detection method for short-period non-eclipsing binaries, with the potential to detect in the near future non-transiting brown-dwarf secondaries, or even massive planets.

  18. WIYN OPEN CLUSTER STUDY. XXXVIII. STELLAR RADIAL VELOCITIES IN THE YOUNG OPEN CLUSTER M35 (NGC 2168)

    SciTech Connect

    Geller, Aaron M.; Mathieu, Robert D.; Braden, Ella K.; Meibom, Soeren; Dolan, Christopher J.; Platais, Imants E-mail: mathieu@astro.wisc.edu E-mail: smeibom@cfa.harvard.edu E-mail: imants@pha.jhu.edu

    2010-04-15

    We present 5201 radial-velocity (RV) measurements of 1144 stars as part of an ongoing study of the young (150 Myr) open cluster M35 (NGC 2168). We have observed M35 since 1997, using the Hydra Multi-Object Spectrograph on the WIYN 3.5 m telescope. Our stellar sample covers main-sequence stars over a magnitude range of 13.0 {<=} V {<=} 16.5 (1.6-0.8 M {sub sun}) and extends spatially to a radius of 30 arcmin (7 pc in projection at a distance of 805 pc or {approx}4 core radii). Due to its youth, M35 provides a sample of late-type stars with a range of rotation periods. Therefore, we analyze the RV measurement precision as a function of the projected rotational velocity. For narrow-lined stars (vsin i{<=} 10 km s{sup -1}), the RVs have a precision of 0.5 km s{sup -1}, which degrades to 1.0 km s{sup -1} for stars with vsin i = 50 km s{sup -1}. The RV distribution shows a well-defined cluster peak with a central velocity of -8.16 {+-} 0.05 km s{sup -1}, permitting a clean separation of the cluster and field stars. For stars with {>=}3 measurements, we derive RV membership probabilities and identify RV variables, finding 360 cluster members, 55 of which show significant RV variability. Using these cluster members, we construct a color-magnitude diagram for our stellar sample cleaned of field star contamination. We also compare the spatial distribution of the single and binary cluster members, finding no evidence for mass segregation in our stellar sample. Accounting for measurement precision, we place an upper limit on the RV dispersion of the cluster of 0.81 {+-} 0.08 km s{sup -1}. After correction for undetected binaries, we derive a true RV dispersion of 0.65 {+-} 0.10 km s{sup -1}.

  19. Stellar Radial Velocities in the Old Open Cluster M67 (NGC 2682). I. Memberships, Binaries, and Kinematics

    NASA Astrophysics Data System (ADS)

    Geller, Aaron M.; Latham, David W.; Mathieu, Robert D.

    2015-09-01

    We present results from 13776 radial-velocity (RV) measurements of 1278 candidate members of the old (4 Gyr) open cluster M67 (NGC 2682). The measurements are the results of a long-term survey that includes data from seven telescopes with observations for some stars spanning over 40 years. For narrow-lined stars, RVs are measured with precisions ranging from about 0.1 to 0.8 km s-1. The combined stellar sample reaches from the brightest giants in the cluster down to about 4 mag below the main-sequence turnoff (V=16.5), covering a mass range of about 1.34 {M}⊙ to 0.76 {M}⊙ . Spatially, the sample extends to a radus of 30 arcmin (7.4 pc in projection at a distance of 850 pc or 6-7 core radii). We find M67 to have a mean RV of +33.64 km s-1 (with an internal precision of ±0.03 km s-1) well separated from the mean velocity of the field. For stars with ≥slant 3 measurements, we derive RV membership probabilities and identify RV variables, finding 562 cluster members, 142 of which show significant RV variability. We use these cluster members to construct a color-magnitude diagram and identify a rich sample of stars that lie far from the standard single star isochrone, including the well-known blue stragglers, sub-subgiants and yellow giants. These exotic stars have a binary frequency of (at least) 80%, more than three times that detected for stars in the remainder of the sample. We confirm that the cluster is mass segregated, finding the binaries to be more centrally concentrated than the single stars in our sample at the 99.8% confidence level (and at the 98.7% confidence level when only considering main-sequence stars). The blue stragglers are centrally concentrated as compared to the solar-type main-sequence single stars in the cluster at the 99.7% confidence level. Accounting for measurement precision, we derive an RV dispersion in M67 of 0.80 ± 0.04 km s-1 for our sample of single main-sequence stars, subgiants and giants with V≤slant 15.5. When corrected

  20. Retrieval of Precise Radial Velocities from Near-infrared High-resolution Spectra of Low-mass Stars

    NASA Astrophysics Data System (ADS)

    Gao, Peter; Plavchan, P.; Gagné, J.; Furlan, E.; Bottom, M.; Anglada-Escudé, G.; White, R.; Davison, C. L.; Beichman, C.; Brinkworth, C.; Johnson, J.; Ciardi, D.; Wallace, K.; Mennesson, B.; von Braun, K.; Vasisht, G.; Prato, L.; Kane, S. R.; Tanner, A.; Crawford, T. J.; Latham, D.; Rougeot, R.; Geneser, C. S.; Catanzarite, J.

    2016-10-01

    Given that low-mass stars have intrinsically low luminosities at optical wavelengths and a propensity for stellar activity, it is advantageous for radial velocity (RV) surveys of these objects to use near-infrared (NIR) wavelengths. In this work, we describe and test a novel RV extraction pipeline dedicated to retrieving RVs from low-mass stars using NIR spectra taken by the CSHELL spectrograph at the NASA Infrared Telescope Facility, where a methane isotopologue gas cell is used for wavelength calibration. The pipeline minimizes the residuals between the observations and a spectral model composed of templates for the target star, the gas cell, and atmospheric telluric absorption; models of the line-spread function, continuum curvature, and sinusoidal fringing; and a parameterization of the wavelength solution. The stellar template is derived iteratively from the science observations themselves without a need for separate observations dedicated to retrieving it. Despite limitations from CSHELL’s narrow wavelength range and instrumental systematics, we are able to (1) obtain an RV precision of 35 m s-1 for the RV standard star GJ 15 A over a time baseline of 817 days, reaching the photon noise limit for our attained signal-to-noise ratio; (2) achieve ˜3 m s-1 RV precision for the M giant SV Peg over a baseline of several days and confirm its long-term RV trend due to stellar pulsations, as well as obtain nightly noise floors of ˜2-6 m s-1 and (3) show that our data are consistent with the known masses, periods, and orbital eccentricities of the two most massive planets orbiting GJ 876. Future applications of our pipeline to RV surveys using the next generation of NIR spectrographs, such as iSHELL, will enable the potential detection of super-Earths and mini-Neptunes in the habitable zones of M dwarfs.

  1. Radial velocity variations of photometrically quiet, chromospherically inactive Kepler stars: A link between RV jitter and photometric flicker

    SciTech Connect

    Bastien, Fabienne A.; Stassun, Keivan G.; Pepper, Joshua; Wright, Jason T.; Aigrain, Suzanne; Basri, Gibor; Johnson, John A.; Howard, Andrew W.; Walkowicz, Lucianne M.

    2014-02-01

    We compare stellar photometric variability, as measured from Kepler light curves by Basri et al., with measurements of radial velocity (RV) rms variations of all California Planet Search overlap stars. We newly derive rotation periods from the Kepler light curves for all of the stars in our study sample. The RV variations reported herein range from less than 4 to 135 m s{sup –1}, yet the stars all have amplitudes of photometric variability less than 3 mmag, reflecting the preference of the RV program for chromospherically 'quiet' stars. Despite the small size of our sample, we find with high statistical significance that the RV rms manifests strongly in the Fourier power spectrum of the light curve: stars that are noisier in RV have a greater number of frequency components in the light curve. We also find that spot models of the observed light curves systematically underpredict the observed RV variations by factors of ∼2-1000, likely because the low-level photometric variations in our sample are driven by processes not included in simple spot models. The stars best fit by these models tend to have simpler light curves, dominated by a single relatively high-amplitude component of variability. Finally, we demonstrate that the RV rms behavior of our sample can be explained in the context of the photometric variability evolutionary diagram introduced by Bastien et al. We use this diagram to derive the surface gravities of the stars in our sample, revealing many of them to have moved off the main sequence. More generally, we find that the stars with the largest RV rms are those that have evolved onto the 'flicker floor' sequence in that diagram, characterized by relatively low amplitude but highly complex photometric variations which grow as the stars evolve to become subgiants.

  2. Development of a Data Reduction Pipeline to Measure Stellar Radial Velocities Using Kutztown University's On-Campus Research Observatory

    NASA Astrophysics Data System (ADS)

    Fox, Odysseus; Reed, Phillip A.

    2016-01-01

    The Kutztown University Observatory (KUO) houses a 0.6m Ritchey-Chrétien telescope with a focal ratio of f/8. It is a dedicated observatory collecting data every clear night using the eShel model (Shelyak Instruments) echelle spectrograph. The spectral resolution is R = 11,000 and the final dispersion is 0.050 Å/pixel over the range of 4300 Å to 8100 Å.It is paramount to ensure accurate radial velocity (RV) measurements when conducting projects for research and education. RV measurements at KUO are used to determine the masses of spectroscopic binary stars, study pulsations of stellar photospheres (Cepheid variables), and to perform reconnaissance RV measurements of exoplanet candidates (reflex motion of host star).We present a data reduction pipeline program that produces RV measurements from observed spectra. After using the eShel's built in ThAr lamp for wavelength calibration, the program continuum normalizes the spectrum, creates a non-moving template (synthetic and/or observed spectrum), and corrects for barycentric motion. Finally, the program performs a cross correlation of the data and template to produce accurate RV measurements.Examples of completed and on-going projects at KUO are presented. We also demonstrate our ability to observe stellar RV's with uncertainties as good as 0.13 km/s. The eShel spectrograph is commercially available and is becoming popular among users of smaller telescopes. This data reduction pipeline will be useful to the increasing number of researchers utilizing the eShel spectrograph.

  3. Radial velocities of very low mass stars and candidate brown dwarf members of the Hyades and Pleiades, 2

    NASA Technical Reports Server (NTRS)

    Stauffer, John R.; Liebert, James; Giampapa, Mark

    1995-01-01

    We have determined H alpha equivalent widths and radial velocities with 1 sigma accuracies of approximately 5 km/s for approximately 20 candidate very low mass members of the Pleiades cluster and for a few proposed very low mass members of the Hyades. Most of the Pleiades targets were selected from the recent Hambly, Hawkins, and Jameson proper motion survey, where they were identified as probable Pleiades brown dwarfs with an age spread from 3 to 70 Myr. Our spectroscopic data and a reinterpretation of the photometric data confirm that these objects are indeed likely Pleiades members; however, we believe that they more likely have masses slightly above the hydrogen burning mass limit and that there is no firm evidence for an age spread amongst these stars. All of the very low mass Pleiades and Hyades members show H alpha in emission. However, the ratio of H alpha flux to biometric flux in the Pleiades shows a maximum near M(sub Bol) approximately equal to 9.5 (M approximately equal to 0.3 solar mass) and a sharp decrease to lower masses. This break occurs at the approximate mass where low mass stars are expected to become fully convective, and it is tempting to assume that the decrease in H alpha flux is caused by some change in the behavior of stellar dynamos at this mass. We do not see a similar break in activity at this mass in the Hyades. We discuss possible evolutionary explanations for this difference in the H alpha activity between the two clusters.

  4. PRL advanced radial-velocity all-sky search (PARAS): an efficient fiber-fed spectrograph for planet searches

    NASA Astrophysics Data System (ADS)

    Chakraborty, Abhijit; Richardson, Eric Harvey; Mahadevan, Suvrath

    2008-07-01

    We present here the optical design of an efficient Fiber-fed, Prism Cross-dispersed, Echelle Spectrograph (Resolution ~70,000 @seeing limited ~2arcsecs conditions) which will operate in the wavelength region of 3700A to 8100A. It will be used for extra-solar planets searches down to the precision of 3m/s and as well as for follow-up observations for new transit discoveries. The spectrograph design is such that with a beam size of 100mm (4inch) it should suit the existing 1 to 2m class of telescopes available in India. The fiber-fed spectrograph will be installed with a 1.2m telescope, which is situated at Mt. Abu (5800feet), Rajasthan, India. We estimate the spectrograph to be >30% efficient from the slit to the CCD detector, and up to 15% efficient including sky, telescope, fiber-fed optics etc. We expect to reach the S/N ratio of 70 on a 10mag star for an integration time of 40mins. We aim to achieve 5m/s to 3m/s Radial Velocity accuracies on such a star using the simultaneous ThAr referencing method. Since thermal stability is absolutely necessary to achieve <5m/s RV accuracies, the whole spectrograph is planned to be kept inside a vibration free isolated tank under low vacuum (0.001 mbar) in a thermally isolated room at 28C +/- 0.01C. It should see the first light by the summer of 2009. We are guaranteed at least 120 nights per year for the planet search program, more nights are possible.

  5. Search for Close-in Planets around Evoloved Stars with Phase-curve variations and Radial Velocity Measurements

    NASA Astrophysics Data System (ADS)

    Hirano, Teruyuki; Sato, Bun'ei; Masuda, Kento; Benomar, Othman Michel; Takeda, Yoichi; Omiya, Masashi; Harakawa, Hiroki

    2015-08-01

    Tidal interactions are a key process to understand the evolution history of close-in exoplanets. But tidal interactions still have a large uncertainty in their prediction for the damping timescales of stellar obliquity and semi-major axis (e.g., Winn et al. 2010). In the past year, we have worked on a search for (transiting) giant planets around evolved stars, for which few close-in planets were discovered. It has been reported that evolved stars lack close-in planets, which is often attributed to the tidal evolution and/or engulfment of close-in planets by the hosts. Meanwhile, Kepler spacecraft has detected a significant fraction of transiting planet candidates around evolved stars. Confirming the planetary nature for these candidates is especially important in the sense that the comparion between the occurence rates of close-in planets around main sequence stars and evolved stars provides a unique opportunity to discuss the final stage of close-in planets, including tidal evolutions.In this presentation, we review our effort to search for close-in planets around evolved stars. With the aim of confirming KOI planet candidates around evolved stars, we measured precision radial velocities (RVs) for evoloved stars with transiting planet candidates using Subaru/HDS. We also developed a new code which simultaneously models and fits the observed RVs and phase-curve variations in the Kepler light curve data (e.g., transits, stellar ellipsoidal variations, and planet emission/reflected light). As a result of applying the global fit to KOI giants/subgiants, we confirmed a few giant planets around evolved stars (Kepler-91 and KOI-1894), as well as revealed that KOI-977 is more likely a false positive.

  6. The effects of ischemia with and without remote conditioning on hyperemia induced decline in carotid-radial pulse wave velocity.

    PubMed

    Onegbu, Nwamaka; Kamran, Haroon; Sharma, Bhawna; Bapat, Manasi; Littman, Stephen; Warrier, Nikhil; Patel, Rinkesh; Khalid, Muhammad Tanweer; Salciccioli, Louis; Lazar, Jason M

    2012-01-01

    Ischemic conditioning has long held promise for preventing ischemic-reperfusion (I-R) injury. Although a number of studies have evaluated the effects of brief repeated episodes of ischemia before a prolonged ischemic episode on the cardiovascular system using clinical endpoints, more sensitive techniques by which to measure its effects are lacking. Since endothelial function is sensitive to I-R injury, flow mediated dilation of the brachial artery has been proposed for this purpose, but has significant limitations. Hyperemia normally decreases carotid to radial pulse wave velocity (PWV). Accordingly, we sought to determine the effects of I-R injury and ischemic conditioning on the hyperemic change (Δ) in PWV. We induced hyperemia by release of arterial cuff occlusion before and after ipsilateral arm I-R injury (7.5min occlusion) in 25 healthy males, age 29±6 years. The protocol was repeated on 2 occasions in combination with either pre- or post- conditioning stimuli (3× 30s contralateral arm occlusions). Hyperemia resulted in a significant decrease (-13.7%, p<.001) before but not after prolonged ischemia (-0.88%, p=0.40). I-R along with either pre- or post-ischemic conditioning restored the PWV decline (pre: -11.0%, p<0.001; post: -9.9%, p<0.001). In conclusion, 7.5min ischemia blunts the normal PWV decline produced by hyperemia. Remote pre- and post-conditioning restores this response. This technique may be useful for the assessment of novel treatment strategies and mechanisms underlying remote pre- and post-ischemic conditioning in protecting the cardiovascular system.

  7. Radial velocity variable, hot post-AGB stars from the MUCHFUSS project. Classification, atmospheric parameters, formation scenarios

    NASA Astrophysics Data System (ADS)

    Reindl, N.; Geier, S.; Kupfer, T.; Bloemen, S.; Schaffenroth, V.; Heber, U.; Barlow, B. N.; Østensen, R. H.

    2016-03-01

    In the course of the MUCHFUSS project we recently discovered four radial velocity (RV) variable, hot (Teff≈ 80 000-110 000 K) post-asymptotic giant branch (AGB) stars. Among them, we found the first known RV variable O(He) star, the only second known RV variable PG 1159 close binary candidate, as well as the first two naked (i.e., without planetary nebula (PN)) H-rich post-AGB stars of spectral type O(H) that show significant RV variations. We present a non-LTE spectral analysis of these stars along with one further O(H)-type star whose RV variations were found to be not significant. We also report the discovery of a far-infrared excess in the case of the PG 1159 star. None of the stars in our sample displays nebular emission lines, which can be explained well in terms of a very late thermal pulse evolution in the case of the PG 1159 star. The "missing" PNe around the O(H)-type stars seems strange, since we find that several central stars of PNe have much longer post-AGB times. Besides the non-ejection of a PN, the occurrence of a late thermal pulse, or the re-accretion of the PN in the previous post-AGB evolution offer possible explanations for those stars not harbouring a PN (anymore). In the case of the O(He) star J0757, we speculate that it might have been previously part of a compact He transferring binary system. In this scenario, the mass transfer must have stopped after a certain time, leaving behind a low-mass close companion that may be responsible for the extreme RV shift of 107.0 ± 22.0 km s-1 that was measured within only 31 min.

  8. CHARACTERIZING THE ORBITAL AND DYNAMICAL STATE OF THE HD 82943 PLANETARY SYSTEM WITH KECK RADIAL VELOCITY DATA

    SciTech Connect

    Tan, Xianyu; Lee, Man Hoi; Payne, Matthew J.; Ford, Eric B.; Howard, Andrew W.; Johnson, John A.; Marcy, Geoff W.; Wright, Jason T.

    2013-11-10

    We present an updated analysis of radial velocity data of the HD 82943 planetary system based on 10 yr of measurements obtained with the Keck telescope. Previous studies have shown that the HD 82943 system has two planets that are likely in 2:1 mean-motion resonance (MMR), with orbital periods about 220 and 440 days. However, alternative fits that are qualitatively different have also been suggested, with two planets in a 1:1 resonance or three planets in a Laplace 4:2:1 resonance. Here we use χ{sup 2} minimization combined with a parameter grid search to investigate the orbital parameters and dynamical states of the qualitatively different types of fits, and we compare the results to those obtained with the differential evolution Markov chain Monte Carlo method. Our results support the coplanar 2:1 MMR configuration for the HD 82943 system, and show no evidence for either the 1:1 or three-planet Laplace resonance fits. The inclination of the system with respect to the sky plane is well constrained at 20{sup +4.9}{sub -5.5} degrees, and the system contains two planets with masses of about 4.78 M{sub J} and 4.80 M{sub J} (where M{sub J} is the mass of Jupiter) and orbital periods of about 219 and 442 days for the inner and outer planet, respectively. The best fit is dynamically stable with both eccentricity-type resonant angles θ{sub 1} and θ{sub 2} librating around 0°.

  9. PlanetPack: A radial-velocity time-series analysis tool facilitating exoplanets detection, characterization, and dynamical simulations

    NASA Astrophysics Data System (ADS)

    Baluev, Roman V.

    2013-08-01

    We present PlanetPack, a new software tool that we developed to facilitate and standardize the advanced analysis of radial velocity (RV) data for the goal of exoplanets detection, characterization, and basic dynamical N-body simulations. PlanetPack is a command-line interpreter, that can run either in an interactive mode or in a batch mode of automatic script interpretation. Its major abilities include: (i) advanced RV curve fitting with the proper maximum-likelihood treatment of unknown RV jitter; (ii) user-friendly multi-Keplerian as well as Newtonian N-body RV fits; (iii) use of more efficient maximum-likelihood periodograms that involve the full multi-planet fitting (sometimes called as “residual” or “recursive” periodograms); (iv) easily calculatable parametric 2D likelihood function level contours, reflecting the asymptotic confidence regions; (v) fitting under some useful functional constraints is user-friendly; (vi) basic tasks of short- and long-term planetary dynamical simulation using a fast Everhart-type integrator based on Gauss-Legendre spacings; (vii) fitting the data with red noise (auto-correlated errors); (viii) various analytical and numerical methods for the tasks of determining the statistical significance. It is planned that further functionality may be added to PlanetPack in the future. During the development of this software, a lot of effort was made to improve the calculational speed, especially for CPU-demanding tasks. PlanetPack was written in pure C++ (standard of 1998/2003), and is expected to be compilable and useable on a wide range of platforms.

  10. Radial velocities and metallicities from infrared Ca ii triplet spectroscopy of open clusters. II. Berkeley 23, King 1, NGC 559, NGC 6603, and NGC 7245

    NASA Astrophysics Data System (ADS)

    Carrera, R.; Casamiquela, L.; Ospina, N.; Balaguer-Núñez, L.; Jordi, C.; Monteagudo, L.

    2015-06-01

    Context. Open clusters are key to studying the formation and evolution of the Galactic disc. However, there is a deficiency of radial velocity and chemical abundance determinations for open clusters in the literature. Aims: We intend to increase the number of determinations of radial velocities and metallicities from spectroscopy for open clusters. Methods: We acquired medium-resolution spectra (R ~ 8000) in the infrared region Ca ii triplet lines (~8500 Å) for several stars in five open clusters with the long-slit IDS spectrograph on the 2.5 m Isaac Newton Telescope (Roque de los Muchachos Observatory, Spain). Radial velocities were obtained by cross-correlation fitting techniques. The relationships available in the literature between the strength of infrared Ca ii lines and metallicity were also used to derive the metallicity for each cluster. Results: We obtain ⟨Vr⟩ = 48.6 ± 3.4, -58.4 ± 6.8, 26.0 ± 4.3, and -65.3 ± 3.2 km s-1 for Berkeley 23, NGC 559, NGC 6603, and NGC 7245, respectively. We found [ Fe/H ] = -0.25 ± 0.14 and -0.15 ± 0.18 for NGC 559 and NGC 7245, respectively. Berkeley 23 has low metallicity, [ Fe/H ] = -0.42 ± 0.13, which is similar to other open clusters in the outskirts of the Galactic disc. In contrast, we derived high metallicity ([ Fe/H ] = +0.43 ± 0.15) for NGC 6603, which places this system among the most metal-rich known open clusters. To our knowledge, this is the first determination of radial velocities and metallicities from spectroscopy for these clusters, except NGC 6603, for which radial velocities had been previously determined. We have also analysed ten stars in the line of sight to King 1. Because of the large dispersion obtained in both radial velocity and metallicity, we cannot be sure that we have sampled true cluster members. Based on observations made with the 2.5 m Isaac Newton Telescope operated on the island of La Palma by the Isaac Newton Group in the Spanish Observatorio del Roque de los Muchachos of the

  11. Effect of ion orbit loss on the structure in the H-mode tokamak edge pedestal profiles of rotation velocity, radial electric field, density, and temperature

    SciTech Connect

    Stacey, Weston M.

    2013-09-15

    An investigation of the effect of ion orbit loss of thermal ions and the compensating return ion current directly on the radial ion flux flowing in the plasma, and thereby indirectly on the toroidal and poloidal rotation velocity profiles, the radial electric field, density, and temperature profiles, and the interpretation of diffusive and non-diffusive transport coefficients in the plasma edge, is described. Illustrative calculations for a high-confinement H-mode DIII-D [J. Luxon, Nucl. Fusion 42, 614 (2002)] plasma are presented and compared with experimental results. Taking into account, ion orbit loss of thermal ions and the compensating return ion current is found to have a significant effect on the structure of the radial profiles of these quantities in the edge plasma, indicating the necessity of taking ion orbit loss effects into account in interpreting or predicting these quantities.

  12. Precise radial velocities of giant stars. VI. A possible 2:1 resonant planet pair around the K giant star η Ceti

    NASA Astrophysics Data System (ADS)

    Trifonov, Trifon; Reffert, Sabine; Tan, Xianyu; Lee, Man Hoi; Quirrenbach, Andreas

    2014-08-01

    We report the discovery of a new planetary system around the K giant η Cet (HIP 5364, HD 6805, HR 334) based on 118 high-precision optical radial velocities taken at Lick Observatory since July 2000. Since October 2011 an additional nine near-infrared Doppler measurements have been taken using the ESO CRIRES spectrograph (VLT, UT1). The visible data set shows two clear periodicities. Although we cannot completely rule out that the shorter period is due to rotational modulation of stellar features, the infrared data show the same variations as in the optical, which strongly supports that the variations are caused by two planets. Assuming the mass of η Cet to be 1.7 M⊙, the best edge-on coplanar dynamical fit to the data is consistent with two massive planets (mb sini = 2.6 ± 0.2 MJup, mc sini = 3.3 ± 0.2 MJup), with periods of Pb = 407 ± 3 days and Pc = 740 ± 5 days and eccentricities of eb = 0.12 ± 0.05 and ec = 0.08 ± 0.04. These mass and period ratios suggest possible strong interactions between the planets, and a dynamical test is mandatory. We tested a wide variety of edge-on coplanar and inclined planetary configurations for stability, which agree with the derived radial velocities. We find that for a coplanar configuration there are several isolated stable solutions and two well defined stability regions. In certain orbital configurations with moderate eb eccentricity, the planets can be effectively trapped in an anti-aligned 2:1 mean motion resonance that stabilizes the system. A much larger non-resonant stable region exists in low-eccentricity parameter space, although it appears to be much farther from the best fit than the 2:1 resonant region. In all other cases, the system is categorized as unstable or chaotic. Another conclusion from the coplanar inclined dynamical test is that the planets can be at most a factor of ~1.4 more massive than their suggested minimum masses. Assuming yet higher inclinations, and thus larger planetary masses, leads

  13. The ejection of shells in the stellar wind of P CYG - The most plausible explanation of the Balmer-line radial velocity variations

    NASA Astrophysics Data System (ADS)

    Markova, N.

    1986-07-01

    Our new data of the Balmer line radial velocities in the P Cygni spectrum are compared to the measurments published by de Groot (1969), Kolka (1983) and Markova (1986). The observed variations are analysed in terms of a model proposed by Kolka (1983) which implies a multiple ejection of shells in the stellar wind of P Cygni. It is shown that all data agree to an ejection time scale of about 200 days. The estimated accelerations for the three data groups are very close which supposes a stability of the ejection mechanism over an interval of about 40 yr. The radial velocities of nalmer and the FeII and FeIII (far UV) lines are compared. The identity of the Balmer and the FeII and FeIII shells is discussed.

  14. THE MASS OF THE CANDIDATE EXOPLANET COMPANION TO HD 136118 FROM HUBBLE SPACE TELESCOPE ASTROMETRY AND HIGH-PRECISION RADIAL VELOCITIES

    SciTech Connect

    Martioli, Eder; McArthur, Barbara E.; Benedict, G. Fritz; Armstrong, Amber; Bean, Jacob L.; Harrison, Thomas E.

    2010-01-01

    We use Hubble Space Telescope fine guidance sensor astrometry and high-cadence radial velocities for HD 136118 from the Hobby-Eberly Telescope with archival data from Lick to determine the complete set of orbital parameters for HD 136118 b. We find an orbital inclination for the candidate exoplanet of i{sub b} = 163.{sup 0}1 +- 3.{sup 0}0. This establishes the actual mass of the object, M{sub b} = 42{sup +11}{sub -18} M{sub J} , in contrast to the minimum mass determined from the radial velocity data only, M{sub b} sin i approx 12 M{sub J} . Therefore, the low-mass companion to HD 136118 is now identified as a likely brown dwarf residing in the 'brown dwarf desert'.

  15. The CORALIE survey for Southern extra-solar planets. IV. Intrinsic stellar limitations to planet searches with radial-velocity techniques

    NASA Astrophysics Data System (ADS)

    Santos, N. C.; Mayor, M.; Naef, D.; Pepe, F.; Queloz, D.; Udry, S.; Blecha, A.

    2000-09-01

    Activity related phenomena can induce radial-velocity variations, which can be very important when dealing with extra-solar planet search programmes requiring high-precision radial-velocity measurements. In this paper we present a new chromospheric activity index, SCOR, based on the Ca Ii H line central reemission, and constructed using CORALIE spectra. After one year of measurements, values of SCOR are available for a sub-sample of stars of the Geneva extra-solar planet search programme. After transforming the SCOR values into the Mount-Wilson ``S'' scale we obtained values of the Ca Ii H and K flux corrected from photospheric emission (R'HK) for the stars. The first results are presented, and in particular we focus on the study of the relation between the observed radial-velocity scatter and the chromospheric activity index R'HK, for F, G and K dwarfs. Based on observations collected at the La Silla Observatory, ESO (Chile), with the echelle spectrograph CORALIE at the 1.2-m Euler Swiss telescope

  16. The α CrB binary system: A new radial velocity curve, apsidal motion, and the alignment of rotation and orbit axes

    NASA Astrophysics Data System (ADS)

    Schmitt, J. H. M. M.; Schröder, K.-P.; Rauw, G.; Hempelmann, A.; Mittag, M.; González-Pérez, J. N.; Czesla, S.; Wolter, U.; Jack, D.

    2016-02-01

    We present a new radial velocity curve for the two components of the eclipsing spectroscopic binary α CrB. This binary consists of two main-sequence stars of types A and G in a 17.3599-day orbit, according to the data from our robotic TIGRE facility that is located in Guanajuato, Mexico. We used a high-resolution solar spectrum to determine the radial velocities of the weak secondary component by cross-correlation and wavelength referencing with telluric lines for the strongly rotationally broadened primary lines (v sin(i) = 138 km s-1) to obtain radial velocities with an accuracy of a few hundred m/s. We combined our new RV data with older measurements, dating back to 1908 in the case of the primary, to search for evidence of apsidal motion. We find an apsidal motion period between 6600 and 10 600 yr. This value is consistent with the available data for both the primary and secondary and is also consistent with the assumption that the system has aligned orbit and rotation axes.

  17. Some features of the radial-velocity variations of lines of different intensity in the spectrum of HD 93521. Variability of the stellar wind

    NASA Astrophysics Data System (ADS)

    Rzaev, A. Kh.

    2007-12-01

    CCD spectra taken with the PFES echelle spectrograph of the 6-m telescope of the Special Astrophysical Observatory of the Russian Academy of Sciences are used to perform a detailed study of the variability of the profiles of Hell, H β, and H α lines in the spectrum of HD 93521. The pattern and nature of the variability of the Hell lines are similar to those of weak HeI lines and are due to nonradial pulsations. The period and amplitude of the radial-velocity variations are the same for the blue and red halves of the absorption profile but their phases are opposite. The behavior of the variations of H β and H α hydrogen lines relative to their mean profiles is the same as that of strong HeI line and is due to nonradial pulsations. The period and phase of the radial-velocity oscillations are the same for the blue and red halves of the absorption profile but their amplitude are different. The behavior of the radial-velocity variations of the absorption and emission components of the H α line indicates that the latter also are caused by nonradial pulsations. All this is indicative of the complex structure of the stellar wind in the region of its origin. The behavior of variability and wind kinematics differ in different directions and for different regions of the atmosphere and/or envelope.

  18. Synthesizing exoplanet demographics from radial velocity and microlensing surveys. II. The frequency of planets orbiting M dwarfs

    SciTech Connect

    Clanton, Christian; Gaudi, B. Scott

    2014-08-20

    In contrast to radial velocity (RV) surveys, results from microlensing surveys indicate that giant planets with masses greater than the critical mass for core accretion (∼0.1 M {sub Jup}) are relatively common around low-mass stars. Using the methodology developed in the first paper, we predict the sensitivity of M-dwarf RV surveys to analogs of the population of planets inferred by microlensing. We find that RV surveys should detect a handful of super-Jovian (>M {sub Jup}) planets at the longest periods being probed. These planets are indeed found by RV surveys, implying that the demographic constraints inferred from these two methods are consistent. Finally, we combine the results from both methods to estimate planet frequencies spanning wide regions of parameter space. We find that the frequency of Jupiters and super-Jupiters (1 ≲ m{sub p} sin i/M {sub Jup} ≲ 13) with periods 1 ≤ P/days ≤ 10{sup 4} is f{sub J}=0.029{sub −0.015}{sup +0.013}, a median factor of 4.3 (1.5-14 at 95% confidence) smaller than the inferred frequency of such planets around FGK stars of 0.11 ± 0.02. However, we find the frequency of all giant planets with 30 ≲ m{sub p} sin i/M {sub ⊕} ≲ 10{sup 4} and 1 ≤ P/days ≤ 10{sup 4} to be f{sub G}=0.15{sub −0.07}{sup +0.06}, only a median factor of 2.2 (0.73-5.9 at 95% confidence) smaller than the inferred frequency of such planets orbiting FGK stars of 0.31 ± 0.07. For a more conservative definition of giant planets (50 ≲ m{sub p} sin i/M {sub ⊕} ≲ 10{sup 4}), we find f{sub G{sup ′}}=0.11±0.05, a median factor of 2.2 (0.73-6.7 at 95% confidence) smaller than that inferred for FGK stars of 0.25 ± 0.05. Finally, we find the frequency of all planets with 1 ≤ m{sub p} sin i/M {sub ⊕} ≤ 10{sup 4} and 1 ≤ P/days ≤ 10{sup 4} to be f{sub p} = 1.9 ± 0.5.

  19. ASTROMETRY AND RADIAL VELOCITIES OF THE PLANET HOST M DWARF GJ 317: NEW TRIGONOMETRIC DISTANCE, METALLICITY, AND UPPER LIMIT TO THE MASS OF GJ 317b

    SciTech Connect

    Anglada-Escude, Guillem; Boss, Alan P.; Weinberger, Alycia J.; Butler, R. Paul; Thompson, Ian B.; Vogt, Steven S.; Rivera, Eugenio J.

    2012-02-10

    We have obtained precision astrometry of the planet host M dwarf GJ 317 in the framework of the Carnegie Astrometric Planet Search project. The new astrometric measurements give a distance determination of 15.3 pc, 65% further than previous estimates. The resulting absolute magnitudes suggest that it is metal-rich and more massive than previously assumed. This result strengthens the correlation between high metallicity and the presence of gas giants around low-mass stars. At 15.3 pc, the minimal astrometric amplitude for planet candidate GJ 317b is 0.3 mas (edge-on orbit), just below our astrometric sensitivity. However, given the relatively large number of observations and good astrometric precision, a Bayesian Monte Carlo Markov Chain analysis indicates that the mass of planet b has to be smaller than twice the minimum mass with a 99% confidence level, with a most likely value of 2.5 M{sub Jup}. Additional radial velocity (RV) measurements obtained with Keck by the Lick-Carnegie Planet search program confirm the presence of an additional very long period planet candidate, with a period of 20 years or more. Even though such an object will imprint a large astrometric wobble on the star, its curvature is yet not evident in the astrometry. Given high metallicity, and the trend indicating that multiple systems are rich in low-mass companions, this system is likely to host additional low-mass planets in its habitable zone that can be readily detected with state-of-the-art optical and near-infrared RV measurements.

  20. Precise radial velocities of giant stars. IX. HD 59686 Ab: a massive circumstellar planet orbiting a giant star in a 13.6 au eccentric binary system

    NASA Astrophysics Data System (ADS)

    Ortiz, Mauricio; Reffert, Sabine; Trifonov, Trifon; Quirrenbach, Andreas; Mitchell, David S.; Nowak, Grzegorz; Buenzli, Esther; Zimmerman, Neil; Bonnefoy, Mickaël; Skemer, Andy; Defrère, Denis; Lee, Man Hoi; Fischer, Debra A.; Hinz, Philip M.

    2016-10-01

    Context. For over 12 yr, we have carried out a precise radial velocity (RV) survey of a sample of 373 G- and K-giant stars using the Hamilton Échelle Spectrograph at the Lick Observatory. There are, among others, a number of multiple planetary systems in our sample as well as several planetary candidates in stellar binaries. Aims: We aim at detecting and characterizing substellar and stellar companions to the giant star HD 59686 A (HR 2877, HIP 36616). Methods: We obtained high-precision RV measurements of the star HD 59686 A. By fitting a Keplerian model to the periodic changes in the RVs, we can assess the nature of companions in the system. To distinguish between RV variations that are due to non-radial pulsation or stellar spots, we used infrared RVs taken with the CRIRES spectrograph at the Very Large Telescope. Additionally, to characterize the system in more detail, we obtained high-resolution images with LMIRCam at the Large Binocular Telescope. Results: We report the probable discovery of a giant planet with a mass of mp sin i = 6.92-0.24+0.18 MJup orbiting at ap = 1.0860-0.0007+0.0006 au from the giant star HD 59686 A. In addition to the planetary signal, we discovered an eccentric (eB = 0.729-0.003+0.004) binary companion with a mass of mB sin i = 0.5296-0.0008+0.0011 M⊙ orbiting at a close separation from the giant primary with a semi-major axis of aB = 13.56-0.14+0.18 au. Conclusions: The existence of the planet HD 59686 Ab in a tight eccentric binary system severely challenges standard giant planet formation theories and requires substantial improvements to such theories in tight binaries. Otherwise, alternative planet formation scenarios such as second-generation planets or dynamical interactions in an early phase of the system's lifetime need to be seriously considered to better understand the origin of this enigmatic planet. Based on observations collected at the Lick Observatory, University of California.Based on observations collected at the

  1. EnKF OSSE Experiments Assessing the Impact of HIRAD Wind Speed and HIWRAP Radial Velocity Data on Analysis of Hurricane Karl (2010)

    NASA Technical Reports Server (NTRS)

    Albers, Cerese; Sippel, Jason A.; Braun, Scott A.; Miller, Timothy

    2012-01-01

    Previous studies (e.g., Zhang et al. 2009, Weng et al. 2011) have shown that radial velocity data from airborne and ground-based radars can be assimilated into ensemble Kalman filter (EnKF) systems to produce accurate analyses of tropical cyclone vortices, which can reduce forecast intensity error. Recently, wind speed data from SFMR technology has also been assimilated into the same types of systems and has been shown to improve the forecast intensity of mature tropical cyclones. Two instruments that measure these properties were present during the NASA Genesis and Rapid Intensification Processes (GRIP) field experiment in 2010 which sampled Hurricane Karl, and will next be co-located on the same aircraft for the subsequent NASA HS3 experiment. The High Altitude Wind and Rain Profiling Radar (HIWRAP) is a conically scanning Doppler radar mounted upon NASAs Global Hawk unmanned aerial vehicle, and the usefulness of its radial velocity data for assimilation has not been previously examined. Since the radar scans from above with a fairly large fixed elevation angle, it observes a large component of the vertical wind, which could degrade EnKF analyses compared to analyses with data taken from lesser elevation angles. The NASA Hurricane Imaging Radiometer (HIRAD) is a passive microwave radiometer similar to SFMR, and measures emissivity and retrieves hurricane surface wind speeds and rain rates over a much wider swath. Thus, this study examines the impact of assimilating simulated HIWRAP radial velocity data into an EnKF system, simulated HIRAD wind speed, and HIWRAP+HIRAD with the Weather Research and Forecasting (WRF) model and compares the results to no data assimilation and also to the Truth from which the data was simulated for both instruments.

  2. Friends of hot Jupiters. I. A radial velocity search for massive, long-period companions to close-in gas giant planets

    SciTech Connect

    Knutson, Heather A.; Ngo, Henry; Johnson, John Asher; Fulton, Benjamin J.; Howard, Andrew W.; Montet, Benjamin T.; Kao, Melodie; Hinkley, Sasha; Morton, Timothy D.; Muirhead, Philip S.; Crepp, Justin R.; Bakos, Gaspar Á.; Batygin, Konstantin

    2014-04-20

    In this paper we search for distant massive companions to known transiting gas giant planets that may have influenced the dynamical evolution of these systems. We present new radial velocity observations for a sample of 51 planets obtained using the Keck HIRES instrument, and find statistically significant accelerations in fifteen systems. Six of these systems have no previously reported accelerations in the published literature: HAT-P-10, HAT-P-22, HAT-P-29, HAT-P-32, WASP-10, and XO-2. We combine our radial velocity fits with Keck NIRC2 adaptive optics (AO) imaging data to place constraints on the allowed masses and orbital periods of the companions responsible for the detected accelerations. The estimated masses of the companions range between 1-500 M {sub Jup}, with orbital semi-major axes typically between 1-75 AU. A significant majority of the companions detected by our survey are constrained to have minimum masses comparable to or larger than those of the transiting planets in these systems, making them candidates for influencing the orbital evolution of the inner gas giant. We estimate a total occurrence rate of 51% ± 10% for companions with masses between 1-13 M {sub Jup} and orbital semi-major axes between 1-20 AU in our sample. We find no statistically significant difference between the frequency of companions to transiting planets with misaligned or eccentric orbits and those with well-aligned, circular orbits. We combine our expanded sample of radial velocity measurements with constraints from transit and secondary eclipse observations to provide improved measurements of the physical and orbital characteristics of all of the planets included in our survey.

  3. Additional Constraints on the Shallow Seismic Velocity Structure of the Atlantis Massif Oceanic Core Complex

    NASA Astrophysics Data System (ADS)

    Henig, A. S.; Blackman, D. K.; Harding, A. J.; Kent, G. M.; Canales, J. P.

    2008-12-01

    We investigate the detailed structure of the uppermost ~km of Atlantis Massif, an oceanic core complex at 30°N on the Mid Atlantic Ridge, using pre-existing multichannel seismic data. The Synthetic On- Bottom Experiment (SOBE) method that we employ downward continues both the shots and receivers to a depth just above the seafloor. This allows us to pick refracted arrivals recorded on the streamer at very-near offset, providing constraints from rays that are received within the 300-2000 m range that was unavailable to earlier studies where standard shot gathers had been analyzed. Thus, we can better model the upper few hundred meters of the section which, in turn, adds confidence for determining the deeper (400-1500 m) structure. New work on a ridge-parallel line has been added to last year's work on a cross-axis line over the Central Dome of the massif. Tomographic results are similar for these crossing lines: a thin (100-150 m) low velocity (< 3 km/s) layer caps the dome; high horizontal gradients (>1.25 s-1) occur in local (1-2 km wide) regions within these 6-8 km long subsections of the MCS lines analyzed to date; and very high vertical velocity gradients, greater than 3.75 s-1, occur within the km just below the exposed detachment in these areas. We obtain general agreement with Canales et al., 2008, results over the Central Dome but our models suggest a finer scale lateral heterogeneity. We have begun analysis of additional and extended MCS lines over the domal core of the massif and our priority for this presentation is to assess the detailed structure of the Southern Ridge. In at least some areas the thin, low velocity layer contrasts sufficiently with underlying material that a clear refracted arrival is visible in supergathers. We will determine whether the low velocity layer persists over the whole dome or if it is restricted to the Central Dome. An important question is whether its thickness on the Southern Ridge, if it exists there, differs from that

  4. RADIAL VELOCITY OBSERVATIONS AND LIGHT CURVE NOISE MODELING CONFIRM THAT KEPLER-91b IS A GIANT PLANET ORBITING A GIANT STAR

    SciTech Connect

    Barclay, Thomas; Huber, Daniel; Rowe, Jason F.; Quintana, Elisa V.; Foreman-Mackey, Daniel

    2015-02-10

    Kepler-91b is a rare example of a transiting hot Jupiter around a red giant star, providing the possibility to study the formation and composition of hot Jupiters under different conditions compared to main-sequence stars. However, the planetary nature of Kepler-91b, which was confirmed using phase-curve variations by Lillo-Box et al., was recently called into question based on a re-analysis of Kepler data. We have obtained ground-based radial velocity observations from the Hobby-Eberly Telescope and unambiguously confirm the planetary nature of Kepler-91b by simultaneously modeling the Kepler and radial velocity data. The star exhibits temporally correlated noise due to stellar granulation which we model as a Gaussian Process. We hypothesize that it is this noise component that led previous studies to suspect Kepler-91b to be a false positive. Our work confirms the conclusions presented by Lillo-Box et al. that Kepler-91b is a 0.73 ± 0.13 M {sub Jup} planet orbiting a red giant star.

  5. Radial Velocity Observations and Light Curve Noise Modeling Confirm that Kepler-91b is a Giant Planet Orbiting a Giant Star

    NASA Astrophysics Data System (ADS)

    Barclay, Thomas; Endl, Michael; Huber, Daniel; Foreman-Mackey, Daniel; Cochran, William D.; MacQueen, Phillip J.; Rowe, Jason F.; Quintana, Elisa V.

    2015-02-01

    Kepler-91b is a rare example of a transiting hot Jupiter around a red giant star, providing the possibility to study the formation and composition of hot Jupiters under different conditions compared to main-sequence stars. However, the planetary nature of Kepler-91b, which was confirmed using phase-curve variations by Lillo-Box et al., was recently called into question based on a re-analysis of Kepler data. We have obtained ground-based radial velocity observations from the Hobby-Eberly Telescope and unambiguously confirm the planetary nature of Kepler-91b by simultaneously modeling the Kepler and radial velocity data. The star exhibits temporally correlated noise due to stellar granulation which we model as a Gaussian Process. We hypothesize that it is this noise component that led previous studies to suspect Kepler-91b to be a false positive. Our work confirms the conclusions presented by Lillo-Box et al. that Kepler-91b is a 0.73 ± 0.13 M Jup planet orbiting a red giant star. Based partly on observations obtained with the Hobby-Eberly Telescope, which is a joint project of the University of Texas at Austin, the Pennsylvania State University, Stanford University, Ludwig-Maximilians-Universität München, and Georg-August-Universität Göttingen.

  6. THE ECLIPSING BINARY CEPHEID OGLE-LMC-CEP-0227 IN THE LARGE MAGELLANIC CLOUD: PULSATION MODELING OF LIGHT AND RADIAL VELOCITY CURVES

    SciTech Connect

    Marconi, M.; Molinaro, R.; Bono, G. E-mail: molinaro@oacn.inaf.it; and others

    2013-05-01

    We performed a new and accurate fit of light and radial velocity curves of the Large Magellanic Cloud (LMC) Cepheid-OGLE-LMC-CEP-0227-belonging to a detached double-lined eclipsing binary system. We computed several sets of nonlinear, convective models covering a broad range in stellar mass, effective temperature, and chemical composition. The comparison between theory and observations indicates that current theoretical framework accounts for luminosity-V and I band-and radial velocity variations over the entire pulsation cycle. Predicted pulsation mass-M = 4.14 {+-} 0.06 M{sub Sun }-and mean effective temperature-T{sub e} = 6100 {+-} 50 K-do agree with observed estimates with an accuracy better than 1{sigma}. The same outcome applies, on average, to the luminosity amplitudes and to the mean radius. We find that the best-fit solution requires a chemical composition that is more metal-poor than typical LMC Cepheids (Z = 0.004 versus 0.008) and slightly helium enhanced (Y = 0.27 versus 0.25), but the sensitivity to He abundance is quite limited. Finally, the best-fit model reddening-E(V - I) = 0.171 {+-} 0.015 mag-and the true distance modulus corrected for the barycenter of the LMC-{mu}{sub 0,LMC} = 18.50 {+-} 0.02 {+-} 0.10 (syst) mag-agree quite well with similar estimates in the recent literature.

  7. TRADES: A new software to derive orbital parameters from observed transit times and radial velocities. Revisiting Kepler-11 and Kepler-9

    NASA Astrophysics Data System (ADS)

    Borsato, L.; Marzari, F.; Nascimbeni, V.; Piotto, G.; Granata, V.; Bedin, L. R.; Malavolta, L.

    2014-11-01

    Aims: With the purpose of determining the orbital parameters of exoplanetary systems from observational data, we have developed a software, named TRADES (TRAnsits and Dynamics of Exoplanetary Systems), to simultaneously fit observed radial velocities and transit times data. Methods: We implemented a dynamical simulator for N-body systems, which also fits the available data during the orbital integration and determines the best combination of the orbital parameters using grid search, χ2 minimization, genetic algorithms, particle swarm optimization, and bootstrap analysis. Results: To validate TRADES, we tested the code on a synthetic three-body system and on two real systems discovered by the Kepler mission: Kepler-9 and Kepler-11. These systems are good benchmarks to test multiple exoplanet systems showing transit time variations (TTVs) due to the gravitational interaction among planets. We have found that orbital parameters of Kepler-11 planets agree well with the values proposed in the discovery paper and with a a recent work from the same authors. We analyzed the first three quarters of Kepler-9 system and found parameters in partial agreement with discovery paper. Analyzing transit times (T0s), covering 12 quarters of Kepler data, that we have found a new best-fit solution. This solution outputs masses that are about 55% of the values proposed in the discovery paper; this leads to a reduced semi-amplitude of the radial velocities of about 12.80 ms-1.

  8. SOLAR-LIKE OSCILLATIONS AND ACTIVITY IN PROCYON: A COMPARISON OF THE 2007 MOST AND GROUND-BASED RADIAL VELOCITY CAMPAIGNS

    SciTech Connect

    Huber, Daniel; Bedding, Timothy R.; Stello, Dennis; Arentoft, Torben; Kjeldsen, Hans; Gruberbauer, Michael; Guenther, David B.; Houdek, Guenter; Kallinger, Thomas; Weiss, Werner W.; Matthews, Jaymie M.

    2011-04-20

    We compare the simultaneous 2007 space-based MOST photometry and ground-based radial velocity (RV) observations of the F5 star Procyon. We identify slow variations in the MOST data that are similar to those reported in the RV time series and confirm by comparison with the Sun that these variations are likely the signature of stellar activity. The MOST power spectrum yields clear evidence for individual oscillation frequencies that match those found in the RV data by Bedding et al. We identify the same ridges due to modes of different spherical degree in both data sets, but are not able to confirm a definite ridge identification using the MOST data. We measure the luminosity amplitude per radial mode A{sub l=0,phot} = 9.1 {+-} 0.5 ppm. Combined with the estimate for the RV data by Arentoft et al., this gives a mean amplitude ratio of A{sub l=0,phot}/A{sub l=0,RV} = 0.24 {+-} 0.02 ppm cm{sup -1} s, considerably higher than expected from scaling relations but in reasonable agreement with theoretical models by Houdek. We also compare the amplitude ratio as a function of frequency and find that the maximum of the oscillation envelope is shifted to higher frequencies in photometry than in velocity.

  9. The GMT-CfA, Carnegie, Catolica, Chicago Large Earth Finder (G-CLEF): a general purpose optical echelle spectrograph for the GMT with precision radial velocity capability

    NASA Astrophysics Data System (ADS)

    Szentgyorgyi, A.; Frebel, A.; Furesz, G.; Hertz, E.; Norton, T.; Bean, J.; Bergner, H.; Crane, J.; Evans, J.; Evans, I.; Gauron, T.; Jordán, A.; Park, S.; Uomoto, A.; Barnes, S.; Davis, W.; Eisenhower, M.; Epps, H.; Guzman, D.; McCracken, K.; Ordway, M.; Plummer, D.; Podgorski, W.; Weaver, D.

    2012-09-01

    The GMT-CfA, Carnegie, Catolica, Chicago Large Earth Finder (G-CLEF) is a fiber fed, optical echelle spectrograph that has undergone conceptual design for consideration as a first light instrument at the Giant Magellan Telescope. GCLEF has been designed to be a general-purpose echelle spectrograph with precision radial velocity (PRV) capability. We have defined the performance envelope of G-CLEF to address several of the highest science priorities in the Decadal Survey1. The spectrograph optical design is an asymmetric, two-arm, white pupil design. The asymmetric white pupil design is adopted to minimize the size of the refractive camera lenses. The spectrograph beam is nominally 300 mm, reduced to 200 mm after dispersion by the R4 echelle grating. The peak efficiency of the spectrograph is >35% and the passband is 3500-9500Å. The spectrograph is primarily fed with three sets of fibers to enable three observing modes: High-Throughput, Precision-Abundance and PRV. The respective resolving powers of these modes are R~ 25,000, 40,000 and 120,000. We also anticipate having an R~40,000 Multi-object Spectroscopy mode with a multiplex of ~40 fibers. In PRV mode, each of the seven 8.4m GMT primary mirror sub-apertures feeds an individual fiber, which is scrambled after pupil-slicing. The goal radial velocity precision of G-CLEF is ∂V <10 cm/sec radial. In this paper, we provide a flowdown from fiducial science programs to design parameters. We discuss the optomechanical, electrical, structural and thermal design and present a roadmap to first light at the GMT.

  10. A catalog of K giants at the South Galactic Pole - Broadband and DDO photometry and radial velocities

    NASA Astrophysics Data System (ADS)

    Flynn, C.; Freeman, K. C.

    1993-03-01

    We describe a sample of K giants at the South Galactic Pole, selected to examine the chemical and kinematical properties of stars perpendicular to the galactic plane and to measure the local column density of the disk. We report velocities, abundances, absolute magnitudes, and broadband BV photometry for over 500 giants.

  11. Poloidally and radially resolved parallel D(+) velocity measurements in the DIII-D boundary and comparison to neoclassical computations

    SciTech Connect

    Boedo, J.A.; Belli, E. A.; Hollmann, E. M.; Solomon, W. M.; Rudakov, D. L.; Watkins, J. G.; Prater, R.; Candy, J.; Groebner, R. J.; Burrell, K. H.; DeGrassie, J. S.; Lasnier, C. J.; Leonard, A. W.; Moyer, R.A.; Porter, G. D.; Brooks, N. H.; Muller, S.; Tynan, G.; Unterberg, Ezekial A

    2011-01-01

    First measurements of the D(+) parallel velocity, V(parallel to)(D+), in L-mode discharges in the DIII-D [J. L. Luxon, Nucl. Fusion 42, 614 (2002)] tokamak boundary region at two poloidal locations, 0 similar to 0 degrees and 0 similar to 255 degrees, made using Mach probes, feature a peak with velocities of up to 80 km/s at the midplane last closed flux surface (LCFS), as high as ten times the charge exchange recombination C(6+) toroidal velocity, V(phi)(C6+), in the same location. The V(parallel to)(D+) profiles are very asymmetric poloidally, by a factor of 8-10, and feature a local peak at the midplane. This peak, 1-2 cm wide, is located at or just inside the LCFS, and it suggests a large source of momentum in that location. This momentum source is quantified at similar to 0.31 N m by using a simple momentum transport model. This is the most accurate measurement of the effects of so called "intrinsic" edge momentum source to date. The V(parallel to)(D+) measurements are quantitatively consistent with a purely neoclassical computational modeling of V(parallel to)(D+) by the code NEO [E. A. Belli and J. Candy, Plasma Phys. Controlled Fusion 50, 095010 (2008)], using V(phi)(C6+) as input, for rho similar to 0.7-0.95 at the two poloidal locations, where V(parallel to)(D+) measurements exist. The midplane NEO-calculated V(parallel to)(D+) grows larger than V(phi)(C6+) in the steeper edge gradient region and trends to agreement with the probe-measured V(parallel to)(D+) data near rho similar to 1, where the local V(parallel to)(D+) velocity peak exists. The measurements and computations were made in OH and L-mode discharges on an upper single null, with ion del B(T) drift away from the divertor. The rotating layer finding is similar in auxiliary heated discharges with and without external momentum input, except that at higher density the edge velocity weakens.

  12. Poloidally and radially resolved parallel D+ velocity measurements in the DIII-D boundary and comparison to neoclassical computations

    NASA Astrophysics Data System (ADS)

    Boedo, J. A.; Belli, E. A.; Hollmann, E.; Solomon, W. M.; Rudakov, D. L.; Watkins, J. G.; Prater, R.; Candy, J.; Groebner, R. J.; Burrell, K. H.; deGrassie, J. S.; Lasnier, C. J.; Leonard, A. W.; Moyer, R. A.; Porter, G. D.; Brooks, N. H.; Muller, S.; Tynan, G.; Unterberg, E. A.

    2011-03-01

    First measurements of the D+ parallel velocity, V∥D +, in L-mode discharges in the DIII-D [J. L. Luxon, Nucl. Fusion 42, 614 (2002)] tokamak boundary region at two poloidal locations, θ ˜0° and θ ˜255°, made using Mach probes, feature a peak with velocities of up to 80 km/s at the midplane last closed flux surface (LCFS), as high as ten times the charge exchange recombination C6+ toroidal velocity, VϕC6+, in the same location. The V∥D + profiles are very asymmetric poloidally, by a factor of 8-10, and feature a local peak at the midplane. This peak, 1-2 cm wide, is located at or just inside the LCFS, and it suggests a large source of momentum in that location. This momentum source is quantified at ˜0.31 N m by using a simple momentum transport model. This is the most accurate measurement of the effects of so called "intrinsic" edge momentum source to date. The V∥D + measurements are quantitatively consistent with a purely neoclassical computational modeling of V∥D + by the code NEO [E. A. Belli and J. Candy, Plasma Phys. Controlled Fusion 50, 095010 (2008)], using VϕC6+ as input, for ρ ˜0.7-0.95 at the two poloidal locations, where V∥D + measurements exist. The midplane NEO-calculated V∥D + grows larger than V∥C6+ in the steeper edge gradient region and trends to agreement with the probe-measured V∥D + data near ρ ˜1, where the local V∥D + velocity peak exists. The measurements and computations were made in OH and L-mode discharges on an upper single null, with ion ∇BT drift away from the divertor. The rotating layer finding is similar in auxiliary heated discharges with and without external momentum input, except that at higher density the edge velocity weakens.

  13. THE BROWN DWARF KINEMATICS PROJECT (BDKP). IV. RADIAL VELOCITIES OF 85 LATE-M AND L DWARFS WITH MagE

    SciTech Connect

    Burgasser, Adam J.; Logsdon, Sarah E.; Gagné, Jonathan; Bochanski, John J.; Faherty, Jaqueline K.; West, Andrew A.; Mamajek, Eric E.; Schmidt, Sarah J.; Cruz, Kelle L.

    2015-09-15

    Radial velocity measurements are presented for 85 late M- and L-type very low-mass stars and brown dwarfs obtained with the Magellan Echellette spectrograph. Targets primarily have distances within 20 pc of the Sun, with more distant sources selected for their unusual spectral energy distributions. We achieved precisions of 2–3 km s{sup −1}, and combined these with astrometric and spectrophotometric data to calculate UVW velocities. Most are members of the thin disk of the Galaxy, and velocity dispersions indicate a mean age of 5.2 ± 0.2 Gyr for sources within 20 pc. We find signficantly different kinematic ages between late-M dwarfs (4.0 ± 0.2 Gyr) and L dwarfs (6.5 ± 0.4 Gyr) in our sample that are contrary to predictions from prior simulations. This difference appears to be driven by a dispersed population of unusually blue L dwarfs which may be more prevalent in our local volume-limited sample than in deeper magnitude-limited surveys. The L dwarfs exhibit an asymmetric U velocity distribution with a net inward flow, similar to gradients recently detected in local stellar samples. Simulations incorporating brown dwarf evolution and Galactic orbital dynamics are unable to reproduce the velocity asymmetry, suggesting non-axisymmetric perturbations or two distinct L dwarf populations. We also find the L dwarfs to have a kinematic age-activity correlation similar to more massive stars. We identify several sources with low surface gravities, and two new substellar candidate members of nearby young moving groups: the astrometric binary DENIS J08230313–4912012AB, a low-probability member of the β Pictoris Moving Group; and 2MASS J15104786–2818174, a moderate-probability member of the 30–50 Myr Argus Association.

  14. Observations of the radial velocity of the Sun as measured with the novel SONG spectrograph: results from a 1-week campaign

    NASA Astrophysics Data System (ADS)

    Pallé, P. L.; Grundahl, F.; Triviño Hage, A.; Christensen-Dalsgaard, J.; Frandsen, S.; García, R. A.; Uytterhoeven, K.; Andersen, M. F.; Rasmussen, P. K.; Sørensen, A. N.; Kjeldsen, H.; Spano, P.; Nilsson, H.; Hartman, H.; Jørgensen, U. G.; Skottfelt, J.; Harpsøe, K.; Andersen, M. I.

    2013-06-01

    Deployment of the prototype node of the SONG project took place in April 2012 at Observatorio del Teide (Canary Islands). Its key instrument (echelle spectrograph) was installed and operational a few weeks later while its 1 m feeding telescope suffered a considerable delay to meet the required specifications. Using a fibre-feed, solar light could be fed to the spectrograph and we carried out a 1-week observing campaign in June 2012 to evaluate its performance for measuring precision radial velocities. In this work we present the first results of this campaign by comparing the sensitivity of the SONG spectrograph with other helioseismology reference instruments (Mark-I and GOLF) when simultaneous data are considered.

  15. Performance of an asymmetric short annular diffuser with a nondiverging inner wall using suction. [control of radial profiles of diffuser exit velocity

    NASA Technical Reports Server (NTRS)

    Juhasz, A.

    1974-01-01

    The performance of a short highly asymmetric annular diffuser equipped with wall bleed (suction) capability was evaluated at nominal inlet Mach numbers of 0.188, 0.264, and 0.324 with the inlet pressure and temperature at near ambient values. The diffuser had an area ratio of 2.75 and a length- to inlet-height ratio of 1.6. Results show that the radial profiles of diffuser exit velocity could be controlled from a severely hub peaked to a slightly tip biased form by selective use of bleed. At the same time, other performance parameters were also improved. These results indicate the possible application of the diffuser bleed technique to control flow profiles to gas turbine combustors.

  16. SOAP-T: a tool to study the light curve and radial velocity of a system with a transiting planet and a rotating spotted star

    NASA Astrophysics Data System (ADS)

    Oshagh, M.; Boisse, I.; Boué, G.; Montalto, M.; Santos, N. C.; Bonfils, X.; Haghighipour, N.

    2013-01-01

    We present an improved version of SOAP named "SOAP-T", which can generate the radial velocity variations and light curves for systems consisting of a rotating spotted star with a transiting planet. This tool can be used to study the anomalies inside transit light curves and the Rossiter-McLaughlin effect, to better constrain the orbital configuration and properties of planetary systems and the active zones of their host stars. Tests of the code are presented to illustrate its performance and to validate its capability when compared with analytical models and real data. Finally, we apply SOAP-T to the active star, HAT-P-11, observed by the NASA Kepler space telescope and use this system to discuss the capability of this tool in analyzing light curves for the cases where the transiting planet overlaps with the star's spots. The tool's public interface is available at http://www.astro.up.pt/resources/soap-t/

  17. Synthesizing Exoplanet Demographics: A Single Population of Long-period Planetary Companions to M Dwarfs Consistent with Microlensing, Radial Velocity, and Direct Imaging Surveys

    NASA Astrophysics Data System (ADS)

    Clanton, Christian; Gaudi, B. Scott

    2016-03-01

    We present the first study to synthesize results from five different exoplanet surveys using three independent detection methods: microlensing, radial velocity, and direct imaging. The constraints derived herein represent the most comprehensive picture of the demographics of large-separation (≳2 AU) planets orbiting the most common stars in our Galaxy that has been constructed to date. We assume a simple, joint power-law planet distribution function of the form {d}2{N}{{pl}}/(d{log} {m}p d{log} a)={ A }{({m}p/{M}{{Sat}})}α {(a/2.5{{AU}})}β with an outer cutoff radius of the separation distribution function of aout. Generating populations of planets from these models and mapping them into the relevant observables for each survey, we use actual or estimated detection sensitivities to determine the expected observations for each survey. Comparing with the reported results, we derive constraints on the parameters \\{α ,β ,{ A },{a}{{out}}\\} that describe a single population of planets that is simultaneously consistent with the results of microlensing, radial velocity, and direct imaging surveys. We find median and 68% confindence intervals of α =-{0.86}-0.19+0.21 (-{0.85}-0.19+0.21), β ={1.1}-1.4+1.9 ({1.1}-1.3+1.9), { A }={0.21}-0.15+0.20 {{dex}}-2 ({0.21}-0.15+0.20 {{dex}}-2), and {a}{{out}}={10}-4.7+26 AU ({12}-6.2+50 AU) assuming “hot-start” (“cold-start”) planet evolutionary models. These values are consistent with all current knowledge of planets on orbits beyond ∼2 AU around single M dwarfs.

  18. Solar-like Oscillations and Activity in Procyon: A Comparison of the 2007 MOST and Ground-based Radial Velocity Campaigns

    NASA Astrophysics Data System (ADS)

    Huber, Daniel; Bedding, Timothy R.; Arentoft, Torben; Gruberbauer, Michael; Guenther, David B.; Houdek, Günter; Kallinger, Thomas; Kjeldsen, Hans; Matthews, Jaymie M.; Stello, Dennis; Weiss, Werner W.

    2011-04-01

    We compare the simultaneous 2007 space-based MOST photometry and ground-based radial velocity (RV) observations of the F5 star Procyon. We identify slow variations in the MOST data that are similar to those reported in the RV time series and confirm by comparison with the Sun that these variations are likely the signature of stellar activity. The MOST power spectrum yields clear evidence for individual oscillation frequencies that match those found in the RV data by Bedding et al. We identify the same ridges due to modes of different spherical degree in both data sets, but are not able to confirm a definite ridge identification using the MOST data. We measure the luminosity amplitude per radial mode A l=0,phot = 9.1 ± 0.5 ppm. Combined with the estimate for the RV data by Arentoft et al., this gives a mean amplitude ratio of A l=0,phot/A l=0,RV = 0.24 ± 0.02 ppm cm-1 s, considerably higher than expected from scaling relations but in reasonable agreement with theoretical models by Houdek. We also compare the amplitude ratio as a function of frequency and find that the maximum of the oscillation envelope is shifted to higher frequencies in photometry than in velocity. Based on data from the MOST satellite, a Canadian Space Agency mission, jointly operated by Dynacon Inc., the University of Toronto Institute for Aerospace Studies and the University of British Columbia, with the assistance of the University of Vienna.

  19. Vetting Galactic Leavitt Law Calibrators Using Radial Velocities: On the Variability, Binarity, and Possible Parallax Error of 19 Long-period Cepheids

    NASA Astrophysics Data System (ADS)

    Anderson, R. I.; Casertano, S.; Riess, A. G.; Melis, C.; Holl, B.; Semaan, T.; Papics, P. I.; Blanco-Cuaresma, S.; Eyer, L.; Mowlavi, N.; Palaversa, L.; Roelens, M.

    2016-10-01

    We investigate the radial velocity (RV) variability and spectroscopic binarity of 19 Galactic long-period ({P}{puls} ≳ 10 days) classical Cepheid variable stars whose trigonometric parallaxes are being measured using the Hubble Space Telescope and Gaia. Our primary objective is to constrain possible parallax error due to undetected orbital motion. Using over 1600 high-precision RVs measured between 2011 and 2016, we find no indication of orbital motion on ≲5 year timescales for 18 Cepheids and determine upper limits on allowed configurations for a range of input orbital periods. The results constrain the unsigned parallax error due to orbital motion to <2% for 16 stars, and <4% for 18. We improve the orbital solution of the known binary YZ Carinae and show that the astrometric model must take into account orbital motion to avoid significant error (∼±100 μarcsec). We further investigate long-timescale ({P}{orb} > 10 years) variations in pulsation-averaged velocity v γ via a template fitting approach using both new and literature RVs. We discover the spectroscopic binarity of XZ Car and CD Cyg, find first tentative evidence for AQ Car, and reveal KN Cen’s orbital signature. Further (mostly tentative) evidence of time-variable v γ is found for SS CMa, VY Car, SZ Cyg, and X Pup. We briefly discuss considerations regarding a vetting process of Galactic Leavitt law calibrators and show that light contributions by companions are insignificant for most distance scale applications.

  20. Toward Complete Statistics of Massive Binary Stars: Penultimate Results from the Cygnus OB2 Radial Velocity Survey

    NASA Astrophysics Data System (ADS)

    Kobulnicky, Henry A.; Kiminki, Daniel C.; Lundquist, Michael J.; Burke, Jamison; Chapman, James; Keller, Erica; Lester, Kathryn; Rolen, Emily K.; Topel, Eric; Bhattacharjee, Anirban; Smullen, Rachel A.; Vargas Álvarez, Carlos A.; Runnoe, Jessie C.; Dale, Daniel A.; Brotherton, Michael M.

    2014-08-01

    We analyze orbital solutions for 48 massive multiple-star systems in the Cygnus OB2 association, 23 of which are newly presented here, to find that the observed distribution of orbital periods is approximately uniform in log P for P < 45 days, but it is not scale-free. Inflections in the cumulative distribution near 6 days, 14 days, and 45 days suggest key physical scales of sime0.2, sime0.4, and sime1 A.U. where yet-to-be-identified phenomena create distinct features. No single power law provides a statistically compelling prescription, but if features are ignored, a power law with exponent β ~= -0.22 provides a crude approximation over P = 1.4-2000 days, as does a piece-wise linear function with a break near 45 days. The cumulative period distribution flattens at P > 45 days, even after correction for completeness, indicating either a lower binary fraction or a shift toward low-mass companions. A high degree of similarity (91% likelihood) between the Cyg OB2 period distribution and that of other surveys suggests that the binary properties at P <~ 25 days are determined by local physics of disk/clump fragmentation and are relatively insensitive to environmental and evolutionary factors. Fully 30% of the unbiased parent sample is a binary with period P < 45 days. Completeness corrections imply a binary fraction near 55% for P < 5000 days. The observed distribution of mass ratios 0.2 < q < 1 is consistent with uniform, while the observed distribution of eccentricities 0.1 < e < 0.6 is consistent with uniform plus an excess of e ~= 0 systems. We identify six stars, all supergiants, that exhibit aperiodic velocity variations of ~30 km s-1 attributed to atmospheric fluctuations.

  1. Assimilation of radar radial velocity data with the WRF Hybrid ETKF-3DVAR system for the prediction of Hurricane Ike (2008)

    NASA Astrophysics Data System (ADS)

    Shen, Feifei; Min, Jinzhong; Xu, Dongmei

    2016-03-01

    The impacts of assimilation of radar radial velocity (Vr) data for the application of analyses and forecasts for Hurricane Ike (2008) are investigated using hybrid ensemble transform Kalman filter-three-dimensional variational data assimilation method (Hybrid ETKF-3DVAR) in this study. Radar Vr observations are pre-processed with quality control procedures before they are assimilated using Weather Research and Forecasting and Data Assimilation model (WRFDA) with three-dimensional variational data assimilation (3DVAR) and hybrid method respectively. With the hybrid method, the ensemble mean is updated with the variational method, while the ensemble perturbations are updated by the ETKF. It seems that assimilating Radar Vr data with Hybrid ETKF-3DVAR method is able to adjust the hurricane initial position and dynamic structure significantly, yielding better track and intensity forecast in the data assimilation experiments. Positive temperature increments are found in Hybrid ETKF-3DVAR experiment, indicating a more realistic thermal structure of Hurricane Ike, while 3DVAR experiment produces much smoother and weaker increments with cold temperature increments near the hurricane vortex center at lower levels. Hybrid ETKF-3DVAR further improves the track and intensity forecast accuracy compared to 3DVAR. The ability of the hybrid method in providing flow-dependent background error covariance is the primary reason for its superior performance.

  2. Results from the APOGEE IN-SYNC Orion: parameters and radial velocities for thousands of young stars in the Orion Complex.

    NASA Astrophysics Data System (ADS)

    Da Rio, Nicola; SDSS Apogee IN-SYNC ancillary program Team

    2015-01-01

    I will present the results of our characterization of the dynamical status of the young stellar population in the Orion A star forming region. This is based on radial velocity measurements obtained within the SDSS-III Apogee IN-SYNC Orion Survey, which obtained high-resolution spectroscopy of ~3000 objects in the region, from the dense Orion Nebula Cluster - the prototypical nearby region of active massive star formation - to the low-density environments of the L1641 region. We find evidence for kinematic subclustering along the star forming filament, where the stellar component remains kinematically associated to the gas; in the ONC we find that the stellar population is supervirial and currently expanding. We rule out the existence of a controversial candidate foreground cluster to the south of the ONC. These results, complemented with an analysis of the spatial structure of the population, enables critical tests of theories that describe the formation and early evolution of Orion and young clusters in general.

  3. Additional ECR heating of a radially inhomogeneous plasma via the absorption of satellite harmonics of the surface flute modes in a rippled magnetic field

    SciTech Connect

    Girka, V. O.; Girka, I. O.

    2006-12-15

    A theoretical study is made of the possibility of additional heating of a radially inhomogeneous plasma in confinement systems with a rippled magnetic field via the absorption of satellite harmonics of the surface flute modes with frequencies below the electron gyrofrequency in the local resonance region, {epsilon}{sub 1} (r{sub 1}) = [2{pi}c/({omega}L)]{sup 2}, where {epsilon}{sub 1} is the diagonal element of the plasma dielectric tensor in the hydrodynamic approximation, L is the period of a constant external rippled magnetic field, and the radical coordinate r{sub 1} determines the position of the local resonance. It is found that the high-frequency power absorbed near the local resonance is proportional to the square of the ripple amplitude of the external magnetic field. The mechanism proposed is shown to ensure the absorption of the energy of surface flute modes and, thereby, the heating of a radially inhomogeneous plasma.

  4. THE RADIAL VELOCITY DETECTION OF EARTH-MASS PLANETS IN THE PRESENCE OF ACTIVITY NOISE: THE CASE OF {alpha} CENTAURI Bb

    SciTech Connect

    Hatzes, Artie P.

    2013-06-20

    We present an analysis of the publicly available HARPS radial velocity (RV) measurements for {alpha} Cen B, a star hosting an Earth-mass planet candidate in a 3.24 day orbit. The goal is to devise robust ways of extracting low-amplitude RV signals of low-mass planets in the presence of activity noise. Two approaches were used to remove the stellar activity signal which dominates the RV variations: (1) Fourier component analysis (pre-whitening), and (2) local trend filtering (LTF) of the activity using short time windows of the data. The Fourier procedure results in a signal at P = 3.236 days and K = 0.42 m s{sup -1}, which is consistent with the presence of an Earth-mass planet, but the false alarm probability for this signal is rather high at a few percent. The LTF results in no significant detection of the planet signal, although it is possible to detect a marginal planet signal with this method using a different choice of time windows and fitting functions. However, even in this case the significance of the 3.24 day signal depends on the details of how a time window containing only 10% of the data is filtered. Both methods should have detected the presence of {alpha} Cen Bb at a higher significance than is actually seen. We also investigated the influence of random noise with a standard deviation comparable to the HARPS data and sampled in the same way. The distribution of the noise peaks in the period range 2.8-3.3 days has a maximum of Almost-Equal-To 3.2 days and amplitudes approximately one-half of the K-amplitude for the planet. The presence of the activity signal may boost the velocity amplitude of these signals to values comparable to the planet. It may be premature to attribute the 3.24 day RV variations to an Earth-mass planet. A better understanding of the noise characteristics in the RV data as well as more measurements with better sampling will be needed to confirm this exoplanet.

  5. A High-precision Near-infrared Survey for Radial Velocity Variable Low-mass Stars Using CSHELL and a Methane Gas Cell

    NASA Astrophysics Data System (ADS)

    Gagné, Jonathan; Plavchan, Peter; Gao, Peter; Anglada-Escude, Guillem; Furlan, Elise; Davison, Cassy; Tanner, Angelle; Henry, Todd J.; Riedel, Adric R.; Brinkworth, Carolyn; Latham, David; Bottom, Michael; White, Russel; Mills, Sean; Beichman, Chas; Johnson, John A.; Ciardi, David R.; Wallace, Kent; Mennesson, Bertrand; von Braun, Kaspar; Vasisht, Gautam; Prato, Lisa; Kane, Stephen R.; Mamajek, Eric E.; Walp, Bernie; Crawford, Timothy J.; Rougeot, Raphaël; Geneser, Claire S.; Catanzarite, Joseph

    2016-05-01

    We present the results of a precise near-infrared (NIR) radial velocity (RV) survey of 32 low-mass stars with spectral types K2–M4 using CSHELL at the NASA InfraRed Telescope Facility in the K band with an isotopologue methane gas cell to achieve wavelength calibration and a novel, iterative RV extraction method. We surveyed 14 members of young (≈25–150 Myr) moving groups, the young field star ɛ Eridani, and 18 nearby (<25 pc) low-mass stars and achieved typical single-measurement precisions of 8–15 m s‑1with a long-term stability of 15–50 m s‑1 over longer baselines. We obtain the best NIR RV constraints to date on 27 targets in our sample, 19 of which were never followed by high-precision RV surveys. Our results indicate that very active stars can display long-term RV variations as low as ˜25–50 m s‑1 at ≈2.3125 μm, thus constraining the effect of jitter at these wavelengths. We provide the first multiwavelength confirmation of GJ 876 bc and independently retrieve orbital parameters consistent with previous studies. We recovered RV variabilities for HD 160934 AB and GJ 725 AB that are consistent with their known binary orbits, and nine other targets are candidate RV variables with a statistical significance of 3σ–5σ. Our method, combined with the new iSHELL spectrograph, will yield long-term RV precisions of ≲5 m s‑1 in the NIR, which will allow the detection of super-Earths near the habitable zone of mid-M dwarfs.

  6. MARVELS-1: A FACE-ON DOUBLE-LINED BINARY STAR MASQUERADING AS A RESONANT PLANETARY SYSTEM AND CONSIDERATION OF RARE FALSE POSITIVES IN RADIAL VELOCITY PLANET SEARCHES

    SciTech Connect

    Wright, Jason T.; Roy, Arpita; Mahadevan, Suvrath; Wang, Sharon X.; Fleming, Scott W.; Ford, Eric B.; Payne, Matt; Lee, Brian L.; Ge, Jian; Wang, Ji; Crepp, Justin R.; Gaudi, B. Scott; Eastman, Jason; Pepper, Joshua; Cargile, Phillip; Stassun, Keivan G.; Ghezzi, Luan; Gonzalez-Hernandez, Jonay I.; Wisniewski, John; Dutra-Ferreira, Leticia; and others

    2013-06-20

    We have analyzed new and previously published radial velocity (RV) observations of MARVELS-1, known to have an ostensibly substellar companion in a {approx}6 day orbit. We find significant ({approx}100 m s{sup -1}) residuals to the best-fit model for the companion, and these residuals are naievely consistent with an interior giant planet with a P = 1.965 days in a nearly perfect 3:1 period commensurability (|P{sub b} /P{sub c} - 3| < 10{sup -4}). We have performed several tests for the reality of such a companion, including a dynamical analysis, a search for photometric variability, and a hunt for contaminating stellar spectra. We find many reasons to be critical of a planetary interpretation, including the fact that most of the three-body dynamical solutions are unstable. We find no evidence for transits, and no evidence of stellar photometric variability. We have discovered two apparent companions to MARVELS-1 with adaptive optics imaging at Keck; both are M dwarfs, one is likely bound, and the other is likely a foreground object. We explore false-alarm scenarios inspired by various curiosities in the data. Ultimately, a line profile and bisector analysis lead us to conclude that the {approx}100 m s{sup -1} residuals are an artifact of spectral contamination from a stellar companion contributing {approx}15%-30% of the optical light in the system. We conclude that origin of this contamination is the previously detected RV companion to MARVELS-1, which is not, as previously reported, a brown dwarf, but in fact a G dwarf in a face-on orbit.

  7. A High-precision Near-infrared Survey for Radial Velocity Variable Low-mass Stars Using CSHELL and a Methane Gas Cell

    NASA Astrophysics Data System (ADS)

    Gagné, Jonathan; Plavchan, Peter; Gao, Peter; Anglada-Escude, Guillem; Furlan, Elise; Davison, Cassy; Tanner, Angelle; Henry, Todd J.; Riedel, Adric R.; Brinkworth, Carolyn; Latham, David; Bottom, Michael; White, Russel; Mills, Sean; Beichman, Chas; Johnson, John A.; Ciardi, David R.; Wallace, Kent; Mennesson, Bertrand; von Braun, Kaspar; Vasisht, Gautam; Prato, Lisa; Kane, Stephen R.; Mamajek, Eric E.; Walp, Bernie; Crawford, Timothy J.; Rougeot, Raphaël; Geneser, Claire S.; Catanzarite, Joseph

    2016-05-01

    We present the results of a precise near-infrared (NIR) radial velocity (RV) survey of 32 low-mass stars with spectral types K2-M4 using CSHELL at the NASA InfraRed Telescope Facility in the K band with an isotopologue methane gas cell to achieve wavelength calibration and a novel, iterative RV extraction method. We surveyed 14 members of young (≈25-150 Myr) moving groups, the young field star ɛ Eridani, and 18 nearby (<25 pc) low-mass stars and achieved typical single-measurement precisions of 8-15 m s-1with a long-term stability of 15-50 m s-1 over longer baselines. We obtain the best NIR RV constraints to date on 27 targets in our sample, 19 of which were never followed by high-precision RV surveys. Our results indicate that very active stars can display long-term RV variations as low as ˜25-50 m s-1 at ≈2.3125 μm, thus constraining the effect of jitter at these wavelengths. We provide the first multiwavelength confirmation of GJ 876 bc and independently retrieve orbital parameters consistent with previous studies. We recovered RV variabilities for HD 160934 AB and GJ 725 AB that are consistent with their known binary orbits, and nine other targets are candidate RV variables with a statistical significance of 3σ-5σ. Our method, combined with the new iSHELL spectrograph, will yield long-term RV precisions of ≲5 m s-1 in the NIR, which will allow the detection of super-Earths near the habitable zone of mid-M dwarfs.

  8. KEPLER-18b, c, AND d: A SYSTEM OF THREE PLANETS CONFIRMED BY TRANSIT TIMING VARIATIONS, LIGHT CURVE VALIDATION, WARM-SPITZER PHOTOMETRY, AND RADIAL VELOCITY MEASUREMENTS

    SciTech Connect

    Cochran, William D.; Fabrycky, Daniel C.; Fortney, Jonathan J.

    2011-11-01

    We report the detection of three transiting planets around a Sun-like star, which we designate Kepler-18. The transit signals were detected in photometric data from the Kepler satellite, and were confirmed to arise from planets using a combination of large transit-timing variations (TTVs), radial velocity variations, Warm-Spitzer observations, and statistical analysis of false-positive probabilities. The Kepler-18 star has a mass of 0.97 M{sub sun}, a radius of 1.1 R{sub sun}, an effective temperature of 5345 K, and an iron abundance of [Fe/H] = +0.19. The planets have orbital periods of approximately 3.5, 7.6, and 14.9 days. The innermost planet 'b' is a 'super-Earth' with a mass of 6.9 {+-} 3.4 M{sub +}, a radius of 2.00 {+-} 0.10 R{sub +}, and a mean density of 4.9 {+-} 2.4 g cm{sup 3}. The two outer planets 'c' and 'd' are both low-density Neptune-mass planets. Kepler-18c has a mass of 17.3 {+-} 1.9 M{sub +}, a radius of 5.49 {+-} 0.26 R{sub +}, and a mean density of 0.59 {+-} 0.07 g cm{sup 3}, while Kepler-18d has a mass of 16.4 {+-} 1.4 M{sub +}, a radius of 6.98 {+-} 0.33 R{sub +} and a mean density of 0.27 {+-} 0.03 g cm{sup 3}. Kepler-18c and Kepler-18d have orbital periods near a 2:1 mean-motion resonance, leading to large and readily detected TTVs.

  9. The conjectured S-type retrograde planet in ν Octantis: more evidence including four years of iodine-cell radial velocities

    NASA Astrophysics Data System (ADS)

    Ramm, D. J.; Nelson, B. E.; Endl, M.; Hearnshaw, J. B.; Wittenmyer, R. A.; Gunn, F.; Bergmann, C.; Kilmartin, P.; Brogt, E.

    2016-08-01

    We report 1212 radial-velocity (RV) measurements obtained in the years 2009-2013 using an iodine cell for the spectroscopic binary ν Octantis (K1 III/IV). This system (a_{bin} ˜ 2.6 au, P ˜ 1050 d) is conjectured to have a Jovian planet with a semimajor axis half that of the binary host. The extreme geometry only permits long-term stability if the planet is in a retrograde orbit. Whilst the reality of the planet (P ˜ 415 d) remains uncertain, other scenarios (stellar variability or apsidal motion caused by a yet unobserved third star) continue to appear substantially less credible based on cross-correlation function bisectors, line-depth ratios and many other independent details. If this evidence is validated but the planet is disproved, the claims of other planets using RVs will be seriously challenged. We also describe a significant revision to the previously published RVs and the full set of 1437 RVs now encompasses nearly 13 yr. The sensitive orbital dynamics allow us to constrain the 3D architecture with a broad prior probability distribution on the mutual inclination, which with posterior samples obtained from an N-body Markov chain Monte Carlo is found to be 152.5°±^{0.7}_{0.6}. None of these samples are dynamically stable beyond 106 yr. However, a grid search around the best-fitting solution finds a region that has many models stable for 107 yr, and includes one model within 1σ that is stable for at least 108 yr. The planet's exceptional nature demands robust independent verification and makes the theoretical understanding of its formation a worthy challenge.

  10. Exact simulations of the trajectories of electrons accelerated from rest to relativistic velocities by radially polarized optical pulse: Program and results

    NASA Astrophysics Data System (ADS)

    Cho, Hyun Min

    A relativistic electron co-propagating with a slowly diverging focused 1-cycle, 1-Joule, 1-micron half-wave (111) radially-polarized optical pulse gains nearly 0.43 GeV energy while in a half focal region. In this thesis we describe a new computer program that extends this analytic result to compute the exact trajectory, and its consequences, of an electron initially at rest at any position near the focal region of the incident optical pulse. We have limited the "exact simulation" to try four families of pulse solutions (of Maxwell's equations) which we have found to produce the highest final electron energy or highest amount of re-radiated light, varying the pulse parameters. The nature and statistics of the trajectories having different starting points show that (i) Nearly 100% of initially-at-rest non-interacting electrons struck in the focal volume of the (111) pulse mentioned above are accelerated to final energies between 0.10 and 0.27 GeV. (ii) The standard (111) pulse striking a large volume of initially-at-rest non-interacting electrons creates a cylindrical cavity completely empty of electrons. (iii) An electron struck by a standard (111) optical pulse radiates ˜10 atto-joule, depending on its initial position in the focal region. (iv) We examined our simulation of radiated power from 2 electrons in the focal region and found the expected 4 factor from coherent scattering. We have extended our program to calculating the trajectory of initially-moving electrons. For 155 starting positions one micron apart on a line at 80 degrees to the axis of a standard (111) pulse, and having initial velocity 0.5c, the electron increase its energy by a average of 70 MeV.

  11. Revised FORTRAN program for calculating velocities and streamlines on the hub-shroud midchannel stream surface of an axial-, radial-, or mixed-flow turbomachine or annular duct. 2: Programmer's manual

    NASA Technical Reports Server (NTRS)

    Katsanis, T.; Mcnally, W. D.

    1977-01-01

    A FORTRAN IV computer program has been developed that obtains a detailed subsonic or shock free transonic flow solution on the hub-shroud midchannel stream surface of a turbomachine. The blade row may be fixed or rotating, and the blades may be twisted and leaned. Flow may be axial, mixed, or radial. Upstream and downstream flow variables may vary from hub to shroud, and provisions are made to correct for loss of stagnation pressure. The results include velocities, streamlines, and flow angles on the stream surface and approximate blade surface velocities.

  12. THE RADIAL VELOCITY TATOOINE SEARCH FOR CIRCUMBINARY PLANETS: PLANET DETECTION LIMITS FOR A SAMPLE OF DOUBLE-LINED BINARY STARS-INITIAL RESULTS FROM KECK I/HIRES, SHANE/CAT/HAMSPEC, AND TNG/SARG OBSERVATIONS

    SciTech Connect

    Konacki, Maciej; Helminiak, Krzysztof G.; Muterspaugh, Matthew W.; Kulkarni, Shrinivas R.

    2009-10-10

    We present preliminary results of the first and on-going radial velocity survey for circumbinary planets. With a novel radial velocity technique employing an iodine absorption cell, we achieve an unprecedented radial velocity (RV) precision of up to 2 m s{sup -1} for double-lined binary stars. The high-resolution spectra collected with the Keck I/Hires, TNG/Sarg, and Shane/CAT/Hamspec telescopes/spectrographs over the years 2003-2008 allow us to derive RVs and compute planet detection limits for 10 double-lined binary stars. For this initial sample of targets, we can rule out planets on dynamically stable orbits with masses as small as approx0.3 to 3 M {sub Jup} for the orbital periods of up to approx5.3 years. Even though the presented sample of stars is too small to make any strong conclusions, it is clear that the search for circumbinary planets is now technique-wise possible and eventually will provide new constraints for the planet formation theories.

  13. KELT-8b: A Highly Inflated Transiting Hot Jupiter and a New Technique for Extracting High-precision Radial Velocities from Noisy Spectra

    NASA Astrophysics Data System (ADS)

    Fulton, Benjamin J.; Collins, Karen A.; Gaudi, B. Scott; Stassun, Keivan G.; Pepper, Joshua; Beatty, Thomas G.; Siverd, Robert J.; Penev, Kaloyan; Howard, Andrew W.; Baranec, Christoph; Corfini, Giorgio; Eastman, Jason D.; Gregorio, Joao; Law, Nicholas M.; Lund, Michael B.; Oberst, Thomas E.; Penny, Matthew T.; Riddle, Reed; Rodriguez, Joseph E.; Stevens, Daniel J.; Zambelli, Roberto; Ziegler, Carl; Bieryla, Allyson; D'Ago, Giuseppe; DePoy, Darren L.; Jensen, Eric L. N.; Kielkopf, John F.; Latham, David W.; Manner, Mark; Marshall, Jennifer; McLeod, Kim K.; Reed, Phillip A.

    2015-09-01

    We announce the discovery of a highly inflated transiting hot Jupiter by the KELT-North survey. A global analysis including constraints from isochrones indicates that the V = 10.8 host star (HD 343246) is a mildly evolved, G dwarf with {T}{eff}={5754}-55+54 K, {log} g={4.078}-0.054+0.049, [{Fe}/{{H}}]=0.272+/- 0.038, an inferred mass {M}*={1.211}-0.066+0.078 {M}⊙ , and radius {R}*={1.67}-0.12+0.14 {R}⊙ . The planetary companion has a mass {M}{{P}}={0.867}-0.061+0.065 MJ, radius {R}{{P}}={1.86}-0.16+0.18 RJ, surface gravity {log} {g}{{P}}={2.793}-0.075+0.072, and density {ρ }{{P}}={0.167}-0.038+0.047 g cm-3. The planet is on a roughly circular orbit with semimajor axis a={0.04571}-0.00084+0.00096 AU and eccentricity e={0.035}-0.025+0.050. The best-fit linear ephemeris is {T}0=2456883.4803+/- 0.0007 {{BJD}}{TDB} and P=3.24406+/- 0.00016 days. This planet is one of the most inflated of all known transiting exoplanets, making it one of the few members of a class of extremely low density, highly irradiated gas giants. The low stellar {log} g and large implied radius are supported by stellar density constraints from follow-up light curves, as well as an evolutionary and space motion analysis. We also develop a new technique to extract high-precision radial velocities from noisy spectra that reduces the observing time needed to confirm transiting planet candidates. This planet boasts deep transits of a bright star, a large inferred atmospheric scale height, and a high equilibrium temperature of {T}{eq}={1675}-55+61 K, assuming zero albedo and perfect heat redistribution, making it one of the best targets for future atmospheric characterization studies.

  14. Modelling the magnetic activity and filtering radial velocity curves of young Suns : the weak-line T Tauri star LkCa 4

    NASA Astrophysics Data System (ADS)

    Donati, J.-F.; Hébrard, E.; Hussain, G.; Moutou, C.; Grankin, K.; Boisse, I.; Morin, J.; Gregory, S. G.; Vidotto, A. A.; Bouvier, J.; Alencar, S. H. P.; Delfosse, X.; Doyon, R.; Takami, M.; Jardine, M. M.; Fares, R.; Cameron, A. C.; Ménard, F.; Dougados, C.; Herczeg, G.; Matysse Collaboration

    2014-11-01

    We report results of a spectropolarimetric and photometric monitoring of the weak-line T Tauri star LkCa 4 within the Magnetic Topologies of Young Stars and the Survival of close-in giant Exoplanets (MaTYSSE) programme, involving ESPaDOnS at the Canada-France-Hawaii Telescope. Despite an age of only 2 Myr and a similarity with prototypical classical T Tauri stars, LkCa 4 shows no evidence for accretion and probes an interesting transition stage for star and planet formation. Large profile distortions and Zeeman signatures are detected in the unpolarized and circularly polarized lines of LkCa 4 using Least-Squares Deconvolution (LSD), indicating the presence of brightness inhomogeneities and magnetic fields at the surface of LkCa 4. Using tomographic imaging, we reconstruct brightness and magnetic maps of LkCa 4 from sets of unpolarized and circularly polarized LSD profiles. The large-scale field is strong and mainly axisymmetric, featuring a ≃2 kG poloidal component and a ≃1 kG toroidal component encircling the star at equatorial latitudes - the latter making LkCa 4 markedly different from classical T Tauri stars of similar mass and age. The brightness map includes a dark spot overlapping the magnetic pole and a bright region at mid-latitudes - providing a good match to the contemporaneous photometry. We also find that differential rotation at the surface of LkCa 4 is small, typically ≃5.5 times weaker than that of the Sun, and compatible with solid-body rotation. Using our tomographic modelling, we are able to filter out the activity jitter in the radial velocity curve of LkCa 4 (of full amplitude 4.3 km s-1) down to an rms precision of 0.055 km s-1. Looking for hot Jupiters around young Sun-like stars thus appears feasible, even though we find no evidence for such planets around LkCa 4.

  15. Two New Long-period Giant Planets from the McDonald Observatory Planet Search and Two Stars with Long-period Radial Velocity Signals Related to Stellar Activity Cycles

    NASA Astrophysics Data System (ADS)

    Endl, Michael; Brugamyer, Erik J.; Cochran, William D.; MacQueen, Phillip J.; Robertson, Paul; Meschiari, Stefano; Ramirez, Ivan; Shetrone, Matthew; Gullikson, Kevin; Johnson, Marshall C.; Wittenmyer, Robert; Horner, Jonathan; Ciardi, David R.; Horch, Elliott; Simon, Attila E.; Howell, Steve B.; Everett, Mark; Caldwell, Caroline; Castanheira, Barbara G.

    2016-02-01

    We report the detection of two new long-period giant planets orbiting the stars HD 95872 and HD 162004 ({\\psi }1 Dra B) by the McDonald Observatory planet search. The planet HD 95872b has a minimum mass of 4.6 {M}{{Jup}} and an orbital semimajor axis of 5.2 AU. The giant planet {\\psi }1 Dra Bb has a minimum mass of 1.5 {M}{{Jup}} and an orbital semimajor axis of 4.4 AU. Both of these planets qualify as Jupiter analogs. These results are based on over one and a half decades of precise radial velocity (RV) measurements collected by our program using the McDonald Observatory Tull Coude spectrograph at the 2.7 m Harlan J. Smith Telescope. In the case of {\\psi }1 Dra B we also detect a long-term nonlinear trend in our data that indicates the presence of an additional giant planet, similar to the Jupiter-Saturn pair. The primary of the binary star system, {\\psi }1 Dra A, exhibits a very large amplitude RV variation due to another stellar companion. We detect this additional member using speckle imaging. We also report two cases—HD 10086 and HD 102870 (β Virginis)—of significant RV variation consistent with the presence of a planet, but that are probably caused by stellar activity, rather than reflexive Keplerian motion. These two cases stress the importance of monitoring the magnetic activity level of a target star, as long-term activity cycles can mimic the presence of a Jupiter-analog planet.

  16. Additives

    NASA Technical Reports Server (NTRS)

    Smalheer, C. V.

    1973-01-01

    The chemistry of lubricant additives is discussed to show what the additives are chemically and what functions they perform in the lubrication of various kinds of equipment. Current theories regarding the mode of action of lubricant additives are presented. The additive groups discussed include the following: (1) detergents and dispersants, (2) corrosion inhibitors, (3) antioxidants, (4) viscosity index improvers, (5) pour point depressants, and (6) antifouling agents.

  17. Production, Outflow Velocity, and Radial Distribution of H2O and OH in the Coma of Comet C/1995 O1 [Hale-Bopp] from Wide Field Imaging of OH

    NASA Technical Reports Server (NTRS)

    Harris, Walter M.; Scherb, Frank; Mierkiewicz, Edwin; Oliversen, Ronald; Morgenthaler, Jeffrey

    2001-01-01

    Observations of OH are a useful proxy of the water production rate (Q(sub H2O)) and outflow velocity (V(sub out)) in comets. We use wide field images taken on 03/28/1997 and 04/08/1997 that capture the entire scale length of the OH coma of comet C/1995O1 (Hale-Bopp) to obtain Q(sub H2O) from the model-independent method of aperture summation. We also extract the radial brightness profile of OH 3080 angstroms out to cometocentric distances of up to 10(exp 6) km using an adaptive ring summation algorithm. Radial profiles are obtained as azimuthal averages and in quadrants covering different position angles relative to the comet-Sun line. These profiles are fit using both fixed and variable velocity two-component spherical expansion models to determine VOH with increasing distance from the nucleus. The OH coma of Hale-Bopp was more spatially extended than in previous comets, and this extension is best matched by a variable acceleration of H2O and OH that acted across the entire coma, but was strongest within 1-2 x 10(exp 4) km from the nucleus. This acceleration led to VOH at 10(exp 6) km that was 2-3 times greater than that obtained from a 1P/Halleytype comet at 1 AU, a result that is consistent with gas-kinetic models, extrapolation from previous observations of OH in comets with Q(sub H2O) > 10(exp 29)/s, and radio measurements of the outer coma Hale-Bopp OH velocity profile. When the coma is broken down by quadrant, we find an azimuthal asymmetry in the radial distribution that is characterized by an increase in the spatial extent of OH in the region between the orbit-trailing and anti-sunward directions. Model fits to this area and comparison with radio OH measurements suggest greater acceleration in this region, with VOH UP to 1.5 times greater at 10(exp 6) km radial distance than elsewhere in the coma.

  18. Identifying Coronary Artery Disease in Asymptomatic Middle-Aged Sportsmen: The Additional Value of Pulse Wave Velocity

    PubMed Central

    Braber, Thijs L.; Prakken, Niek H. J.; Mosterd, Arend; Mali, Willem P. Th. M.; Doevendans, Pieter A. F. M.; Bots, Michiel L.; Velthuis, Birgitta K.

    2015-01-01

    Background Cardiovascular screening may benefit middle-aged sportsmen, as coronary artery disease (CAD) is the main cause of exercise-related sudden cardiac death. Arterial stiffness, as measured by pulse wave velocity (PWV), may help identify sportsmen with subclinical CAD. We examined the additional value of PWV measurements to traditional CAD risk factors for identifying CAD. Methods From the Measuring Athlete’s Risk of Cardiovascular events (MARC) cohort of asymptomatic, middle-aged sportsmen who underwent low-dose Cardiac CT (CCT) after routine sports medical examination (SME), 193 consecutive sportsmen (aged 55±6.6 years) were included with additional PWV measurements before CCT. Sensitivity, specificity and predictive values of PWV values (>8.3 and >7.5m/s) assessed by Arteriograph were used to identify CAD (coronary artery calcium scoring ≥100 Agatston Units or coronary CT angiography luminal stenosis ≥50%) and to assess the additional diagnostic value of PWV to established cardiovascular risk factors. Results Forty-seven sportsmen (24%) had CAD on CCT. They were older (58.9 vs. 53.8 years, p<0.001), had more hypertension (17 vs. 4%, p=0.003), higher cholesterol levels (5.7 vs. 5.4mmol/l) p=0.048), and more often were (ever) smokers (55 vs. 34%, p=0.008). Mean PWV was higher in those with CAD (8.9 vs. 8.0 m/s, p=0.017). For PWV >8.3m/s respectively >7.5m/s sensitivity to detect CAD on CT was 43% and 74%, specificity 69% and 45%, positive predictive value 31% and 30%, and negative predictive value 79% and 84%. Adding PWV to traditional risk factor models did not change the area under the curve (from 0.78 (95% CI = 0.709-0.848)) to AUC 0.78 (95% CI 0.710-0.848, p = 0.99)) for prediction of CAD on CCT. Conclusions Limited additional value was found for PWV on top of established risk factors to identify CAD. PWV might still have a role to identify CAD in middle-aged sportsmen if risk factors such as cholesterol are unknown. PMID:26147752

  19. Poloidally and radially resolved parallel D{sup +} velocity measurements in the DIII-D boundary and comparison to neoclassical computations

    SciTech Connect

    Boedo, J. A.; Hollmann, E.; Rudakov, D. L.; Groebner, R. J.; Moyer, R. A.; Porter, G. D.; Muller, S.; Tynan, G.; Belli, E. A.; Prater, R.; Candy, J.; Burrell, K. H.; Grassie, J. S. de; Leonard, A. W.; Brooks, N. H.; Solomon, W. M.; Watkins, J. G.; Lasnier, C. J.; Unterberg, E. A.

    2011-03-15

    First measurements of the D{sup +} parallel velocity, V{sub ||}{sup D+}, in L-mode discharges in the DIII-D [J. L. Luxon, Nucl. Fusion 42, 614 (2002)] tokamak boundary region at two poloidal locations, {theta}{approx}0 deg. and {theta}{approx}255 deg., made using Mach probes, feature a peak with velocities of up to 80 km/s at the midplane last closed flux surface (LCFS), as high as ten times the charge exchange recombination C{sup 6+} toroidal velocity, V{sub {phi}}{sup C6+}, in the same location. The V{sub ||}{sup D+} profiles are very asymmetric poloidally, by a factor of 8-10, and feature a local peak at the midplane. This peak, 1-2 cm wide, is located at or just inside the LCFS, and it suggests a large source of momentum in that location. This momentum source is quantified at {approx}0.31 N m by using a simple momentum transport model. This is the most accurate measurement of the effects of so called 'intrinsic' edge momentum source to date. The V{sub ||}{sup D+} measurements are quantitatively consistent with a purely neoclassical computational modeling of V{sub ||}{sup D+} by the code NEO[E. A. Belli and J. Candy, Plasma Phys. Controlled Fusion 50, 095010 (2008)], using V{sub {phi}}{sup C6+} as input, for {rho}{approx}0.7-0.95 at the two poloidal locations, where V{sub ||}{sup D+} measurements exist. The midplane NEO-calculated V{sub ||}{sup D+} grows larger than V{sub ||}{sup C6+} in the steeper edge gradient region and trends to agreement with the probe-measured V{sub ||}{sup D+} data near {rho}{approx}1, where the local V{sub ||}{sup D+} velocity peak exists. The measurements and computations were made in OH and L-mode discharges on an upper single null, with ion {nabla}B{sub T} drift away from the divertor. The rotating layer finding is similar in auxiliary heated discharges with and without external momentum input, except that at higher density the edge velocity weakens.

  20. Radial engine

    SciTech Connect

    Kmicikiewicz, M.A.

    1988-03-01

    A radial engine is described comprising: a housing; equally spaced openings disposed in ring-like arrangement on the periphery of the housing; a piston and cylinder arrangement in each of the opening, a piston rod for each arrangement fixed to and extending radially inwardly from its respective piston and through its respective opening; shoe means pivotally attached at the other end of each of the piston rod; radial guide means extending in the housing in line with each of the piston rods, and the shoe means provided with guide means followers to ensure radial reciprocal movement of the piston rods and shoe means; and a connecting ring journaled on a crankshaft for circular translation motion in the housing, the ring including a circular rim. Each shoe means includes an arcuate follower member being slidably connected to the rim of the connecting ring.

  1. Radial systems of dark globules

    SciTech Connect

    Gyul'budagyn, A.L.

    1986-03-01

    The author gives examples of radial systems consisting of dark globules and ''elephant trunks''. Besides already known systems, which contain hot stars at their center, data are given on three radial systems of a new kind, at the center of which there are stars of spectral types later than B. Data are given on 32 globules of radial systems of the association Cep OB2. On the basis of the observational data, it is concluded that at least some of the isolated Bok globules derive from elephant trunks and dark globules forming radial systems around hot stars. It is also suggested that the two molecular clouds situated near the Rosette nebula and possessing velocities differing by ca 20 km/sec from the velocity of the nebula could have been ejected in opposite directions from the center of the nebula. One of these clouds consists of dark globules forming the radial system of the Rosette nebula.

  2. A globular cluster toward M87 with a radial velocity < – 1000 km s{sup –1}: the first hypervelocity cluster

    SciTech Connect

    Caldwell, Nelson; Strader, Jay; Romanowsky, Aaron J.; Brodie, Jean P.; Moore, Ben; Diemand, Jurg; Martizzi, Davide

    2014-05-20

    We report the discovery of an object near M87 in the Virgo Cluster with an extraordinary blueshift of –1025 km s{sup –1}, offset from the systemic velocity by >2300 km s{sup –1}. Evaluation of photometric and spectroscopic data provides strong evidence that this object is a distant massive globular cluster, which we call HVGC-1 in analogy to Galactic hypervelocity stars. We consider but disfavor more exotic interpretations, such as a system of stars bound to a recoiling black hole. The odds of observing an outlier as extreme as HVGC-1 in a virialized distribution of intracluster objects are small; it appears more likely that the cluster was (or is being) ejected from Virgo following a three-body interaction. The nature of the interaction is unclear, and could involve either a subhalo or a binary supermassive black hole at the center of M87.

  3. Production, Outflow Velocity, and Radial Distribution of H2O and OH in the Coma of Comet C/1995 O1 [Hale-Bopp] from Wide Field Imaging of OH

    NASA Technical Reports Server (NTRS)

    Harris, Walter M.; Scherb, Frank; Mierkiewicz, Edwin; Oliverson, Ronald; Morgenthaler, Jeffrey

    2003-01-01

    Observations of OH are a useful proxy of the water production rate (Q(sub H2O)) and outflow velocity (V(sub out)) in comets. From wide field images taken on 03/28/1997 and 04/08/1997 that capture the entire scale length of the OH coma of comet C/1995 O1 (Hale-Bopp), we obtain Q(sub H2O) from the model-independent method of aperture summation. With an adaptive ring summation algorithm, we extract the radial brightness distribution of OH 0-0 band emission out to cometocentric distances of up to 10(exp 6) km, both as azimuthal averages and in quadrants covering different position angles relative to the comet-Sun line. These profiles are fit using both fixed and variable velocity 2-component spherical expansion models to estimate V(sub OH) with increasing distance from the nucleus. The OH coma of Hale-Bopp was more spatially extended than previous comets, and this extension is best matched by a variable acceleration of H2O and OH that acted across the entire coma, but was strongest within 1-2 x 10(exp 4) km from the nucleus. Our models indicate that V(sub OH) at the edge of our detectable field of view (10(exp 6) km) was approx. 2-3 times greater in Hale-Bopp than for a 1P/Halley-class comet at 1 AU, which is consistent with the results of more sophisticated gas-kinetic models, extrapolation from previous observations of OH in comets with Q(sub H2O) greater than 10(exp 29)/s , and direct radio measurements of the outer coma Hale-Bopp OH velocity. The most probable source of this acceleration is thermalization of the excess energy of dissociation of H2O and OH over an extended collisional coma. When the coma is broken down by quadrants in position angle, we find an azimuthal asymmetry in the radial distribution that is characterized by an increase in the spatial extent of OH in the region between the orbit-trailing and anti-sunward directions. Model fits specific to this area and comparison with radio OH measurements suggest greater acceleration here, with V(sub OH

  4. Improvement of corrosion resistance of high-velocity oxyfuel-sprayed stainless steel coatings by addition of molybdenum

    NASA Astrophysics Data System (ADS)

    Kawakita, Jin; Kuroda, Seiji; Fukushima, Takeshi; Kodama, Toshiaki

    2005-06-01

    To improve the marine corrosion resistance of stainless steel coatings fabricated by high-velocity oxyfuel (HVOF) spraying with a gas shroud attachment, the molybdenum (Mo) content of stainless steel was increased to form coatings with a chemical composition of Fe balance-18mass%Cr-22mass%Ni-2˜8mass%Mo. These coatings were highly dense, with <0.1 vol.% in porosity, and less oxidized, with 0.5 mass% in oxygen content at most. The corrosion mechanism and resistance of the coatings were investigated by electrochemical measurement, chemical analysis, and statistical processing. The general corrosion resistance of the coatings in 0.5 mol/dm3 sulfuric acid was improved with increases in Mo content, and the corrosion rate could be decreased to 8.8 × 10-2 mg/cm2 per hour (˜1 mm/year) at 8 mass% Mo. The pitting corrosion resistance of the coatings in artificial seawater was improved with increases in Mo content and was superior to that of the 316L stainless steel coating. The crevice corrosion resistance of the coatings in artificial seawater was improved and the number of rust spots at 4 mass% Mo was decreased to 38% of that for the 316L coating. Accordingly, Mo is highly effective in improving the corrosion resistance of the stainless steel coatings by HVOF spraying.

  5. Division IX: Commission 30: Radial Velocities

    NASA Astrophysics Data System (ADS)

    Torres, Guillermo; Pourbaix, Dimitri; Udry, Stephane; Marcy, Geoffrey W.; Mathieu, Robert D.; Mazeh, Tsevi; Minniti, Dante; Moutou, Claire; Pepe, Francesco; Turon, Catherine; Zwitter, Tomaz

    2015-08-01

    The meeting was attended by the President and Vice-President of the Commission, along with approximately 15 other members. The President reported on the election of new officers that took place at the end of March 2012, for four new members of the Organizing Committee as well as a new Vice-President, and thanked the outgoing members. Tomaz Zwitter (Slovenia) was elected as the new VP (2012-2015), and the new OC members for the period 2012-2018 are Alceste Bonanos (Greece), Alain Jorissen (Belgium), David Katz (France), and Matthias Steinmetz (Germany). The current VP, Dimitri Pourbaix, became the President through 2015.

  6. Radial Erosion

    NASA Technical Reports Server (NTRS)

    2005-01-01

    [figure removed for brevity, see original site]

    The ejecta surrounding the crater (off image to the left) in this image has undergone significant erosion by the wind. The wind has stripped the surface features from the ejecta and has started to winnow away the ejecta blanket. Near the margin of the ejecta the wind is eroding along a radial pattern -- taking advantage of radial emplacement. Note the steep margin of the ejecta blanket. Most, if not all, of the fine ejecta material has been removed and the wind in now working on the more massive continuous ejecta blanket.

    Image information: VIS instrument. Latitude 12.5, Longitude 197.4 East (162.6 West). 37 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

  7. Radial-radial single rotor turbine

    DOEpatents

    Platts, David A.

    2006-05-16

    A rotor for use in turbine applications has a radial compressor/pump having radially disposed spaced apart fins forming passages and a radial turbine having hollow turbine blades interleaved with the fins and through which fluid from the radial compressor/pump flows. The rotor can, in some applications, be used to produce electrical power.

  8. Radial propagation of geodesic acoustic modes

    SciTech Connect

    Hager, Robert; Hallatschek, Klaus

    2009-07-15

    The GAM group velocity is estimated from the ratio of the radial free energy flux to the total free energy applying gyrokinetic and two-fluid theory. This method is much more robust than approaches that calculate the group velocity directly and can be generalized to include additional physics, e.g., magnetic geometry. The results are verified with the gyrokinetic code GYRO[J. Candy and R. E. Waltz, J. Comput. Phys. 186, 545 (2003)], the two-fluid code NLET[K. Hallatschek and A. Zeiler, Phys. Plasmas 7, 2554 (2000)], and analytical calculations. GAM propagation must be kept in mind when discussing the windows of GAM activity observed experimentally and the match between linear theory and experimental GAM frequencies.

  9. Radial Inflow Turboexpander Redesign

    SciTech Connect

    William G. Price

    2001-09-24

    Steamboat Envirosystems, LLC (SELC) was awarded a grant in accordance with the DOE Enhanced Geothermal Systems Project Development. Atlas-Copco Rotoflow (ACR), a radial expansion turbine manufacturer, was responsible for the manufacturing of the turbine and the creation of the new computer program. SB Geo, Inc. (SBG), the facility operator, monitored and assisted ACR's activities as well as provided installation and startup assistance. The primary scope of the project is the redesign of an axial flow turbine to a radial inflow turboexpander to provide increased efficiency and reliability at an existing facility. In addition to the increased efficiency and reliability, the redesign includes an improved reduction gear design, and improved shaft seal design, and upgraded control system and a greater flexibility of application

  10. Stationary Plasma Thruster Ion Velocity Distribution

    NASA Technical Reports Server (NTRS)

    Manzella, David H.

    1994-01-01

    A nonintrusive velocity diagnostic based on laser induced fluorescence of the 5d4F(5/2)-6p4D(5/2) singly ionized xenon transition was used to interrogate the exhaust of a 1.5 kW Stationary Plasma Thruster (SPT). A detailed map of plume velocity vectors was obtained using a simplified, cost-effective, nonintrusive, semiconductor laser based scheme. Circumferential velocities on the order of 250 m/s were measured which implied induced momentum torques of approximately 5 x 10(exp -2) N-cm. Axial and radial velocities were evaluated one mm downstream of the cathode at several locations across the width of the annular acceleration channel. Radial velocities varied linearly with radial distance. A maximum radial velocity of 7500 m/s was measured 8 mm from the center of the channel. Axial velocities as large as 16,500 m/s were measured.

  11. Fast Radial Flows in Transition Disk Holes

    NASA Astrophysics Data System (ADS)

    Rosenfeld, Katherine A.; Chiang, Eugene; Andrews, Sean M.

    2014-02-01

    Protoplanetary "transition" disks have large, mass-depleted central cavities, yet also deliver gas onto their host stars at rates comparable to disks without holes. The paradox of simultaneous transparency and accretion can be explained if gas flows inward at much higher radial speeds inside the cavity than outside the cavity, since surface density (and by extension optical depth) varies inversely with inflow velocity at fixed accretion rate. Radial speeds within the cavity might even have to approach free-fall values to explain the huge surface density contrasts inferred for transition disks. We identify observational diagnostics of fast radial inflow in channel maps made in optically thick spectral lines. Signatures include (1) twisted isophotes in maps made at low systemic velocities and (2) rotation of structures observed between maps made in high-velocity line wings. As a test case, we apply our new diagnostic tools to archival Atacama Large Millimeter Array data on the transition disk HD 142527 and uncover evidence for free-fall radial velocities inside its cavity. Although the observed kinematics are also consistent with a disk warp, the radial inflow scenario is preferred because it predicts low surface densities that appear consistent with recent observations of optically thin CO isotopologues in this disk. How material in the disk cavity sheds its angular momentum wholesale to fall freely onto the star is an unsolved problem; gravitational torques exerted by giant planets or brown dwarfs are briefly discussed as a candidate mechanism.

  12. Fast radial flows in transition disk holes

    SciTech Connect

    Rosenfeld, Katherine A.; Andrews, Sean M.; Chiang, Eugene

    2014-02-20

    Protoplanetary 'transition' disks have large, mass-depleted central cavities, yet also deliver gas onto their host stars at rates comparable to disks without holes. The paradox of simultaneous transparency and accretion can be explained if gas flows inward at much higher radial speeds inside the cavity than outside the cavity, since surface density (and by extension optical depth) varies inversely with inflow velocity at fixed accretion rate. Radial speeds within the cavity might even have to approach free-fall values to explain the huge surface density contrasts inferred for transition disks. We identify observational diagnostics of fast radial inflow in channel maps made in optically thick spectral lines. Signatures include (1) twisted isophotes in maps made at low systemic velocities and (2) rotation of structures observed between maps made in high-velocity line wings. As a test case, we apply our new diagnostic tools to archival Atacama Large Millimeter Array data on the transition disk HD 142527 and uncover evidence for free-fall radial velocities inside its cavity. Although the observed kinematics are also consistent with a disk warp, the radial inflow scenario is preferred because it predicts low surface densities that appear consistent with recent observations of optically thin CO isotopologues in this disk. How material in the disk cavity sheds its angular momentum wholesale to fall freely onto the star is an unsolved problem; gravitational torques exerted by giant planets or brown dwarfs are briefly discussed as a candidate mechanism.

  13. Generalized transfers and the nonoptimality of purely radial impulses

    NASA Astrophysics Data System (ADS)

    Lashkin, V. I.

    1985-07-01

    A system of variables is proposed that is convenient for the precise formulation of the problem of optimal multiple-impulse transfer between arbitrary nonrectilinear Kepler orbits. The existence of a universal two-impulse transfer with transverse impulses is demonstrated for such orbits. Calculation formulas for these impulses are obtained which generalize the corresponding formulas of two-impulse Hohmann transfer between circular orbits. In addition, a lower-bound estimate is obtained for the characteristic velocity of a one-impulse transfer between orbits having a common point, and the nonoptimality of an arbitrary radial impulse is demonstrated.

  14. GMTI radar minimum detectable velocity.

    SciTech Connect

    Richards, John Alfred

    2011-04-01

    Minimum detectable velocity (MDV) is a fundamental consideration for the design, implementation, and exploitation of ground moving-target indication (GMTI) radar imaging modes. All single-phase-center air-to-ground radars are characterized by an MDV, or a minimum radial velocity below which motion of a discrete nonstationary target is indistinguishable from the relative motion between the platform and the ground. Targets with radial velocities less than MDV are typically overwhelmed by endoclutter ground returns, and are thus not generally detectable. Targets with radial velocities greater than MDV typically produce distinct returns falling outside of the endoclutter ground returns, and are thus generally discernible using straightforward detection algorithms. This document provides a straightforward derivation of MDV for an air-to-ground single-phase-center GMTI radar operating in an arbitrary geometry.

  15. Radial arm strike rail

    DOEpatents

    McKeown, Mark H.; Beason, Steven C.

    1991-01-01

    The radial arm strike rail assembly is a system for measurement of bearings, directions, and stereophotography for geologic mapping, particularly where magnetic compasses are not appropriate. The radial arm, pivoting around a shaft axis, provides a reference direction determination for geologic mapping and bearing or direction determination. The centerable and levelable pedestal provide a base for the radial arm strike rail and the telescoping camera pedestal. The telescoping feature of the radial arm strike rail allows positioning the end of the rail for strike direction or bearing measurement with a goniometer.

  16. Low-Velocity Halo Clouds

    NASA Astrophysics Data System (ADS)

    Peek, J. E. G.; Heiles, Carl; Putman, M. E.; Douglas, Kevin

    2009-02-01

    Models that reproduce the observed high-velocity clouds (HVCs) also predict clouds at lower radial velocities that may easily be confused with Galactic disk (|z|< 1 kpc) gas. We describe the first search for these low-velocity halo clouds (LVHCs) using Infrared Astronomical Satellite (IRAS) data and the initial data from the Galactic Arecibo L-band Feed Array survey in H I. The technique is based upon the expectation that such clouds should, like HVCs, have very limited infrared (IR) thermal dust emission as compared to their H I column density. We describe our "displacement-map" technique for robustly determining the dust-to-gas ratio (DGR) of clouds and the associated errors that take into account the significant scatter in the IR flux from the Galactic disk gas. We find that there exist lower-velocity clouds that have extremely low DGRs, consistent with being in the Galactic halo—candidate LVHCs. We also confirm the lack of dust in many HVCs with the notable exception of complex M, which we consider to be the first detection of dust in HVCs. We do not confirm the previously reported detection of dust in complex C. In addition, we find that most intermediate- and low-velocity clouds that are part of the Galactic disk have a higher 60 μm/100 μm flux ratio than is typically seen in Galactic H I, which is consistent with a previously proposed picture in which fast-moving Galactic clouds have smaller, hotter dust grains.

  17. Radial and azimuthal dynamics of the Io plasma torus

    NASA Astrophysics Data System (ADS)

    Copper, Matthew

    The moon Io orbits Jupiter emitting neutral particles from its volcanic surface. This emission is ionized and forms the Io plasma torus around Jupiter. The variation of conditions at Io and Jupiter lead to variations in the content of the plasma in the torus. Volcanoes on Io's surface erupt and change the rate of neutral input. Hot electrons (30--100 eV), whose abundances vary in azimuth, create highly ionized species. Radial variation in subcorotation velocities, velocities less than that of the motion of the dipole magnetic field, creates shears while maintaining coherent radial structure in the torus. Poorly understood changes in plasma density circulate through the torus creating the anomalous System IV behavior that has a period slightly longer than the rotation of Jupiter's magnetic field. This thesis summarizes the research that has produced a two-dimensional physical chemistry model, tested several existing theories about subcorotation velocities, System IV variation, and hot electrons, and adopted new methods of Io plasma torus analysis. In an attempt to understand important dynamics, the thesis modeled differing scenarios such as an initialized two-peak structure, a subcorotation profile dictated by mass loading and ionospheric conductivity, and a critical combination of two populations of hot electrons that accurately mimics the observed System IV phenomenon. This model was also used to solve the inverse problem of determining the best fit for the model parameters, neutral source input rate and radial transport rate, using observations of density, temperature, and composition. In addition the thesis shows the need for multi-dimensional modeling and the results from its groundbreaking two-dimensional model.

  18. Solutions to bi-Maxwellian transport equations for radial solar wind beyond 28 R(S)

    NASA Technical Reports Server (NTRS)

    Demars, H. G.; Schunk, R. W.

    1991-01-01

    This paper presents solar wind solutions for radial flow between 28 solar radii and 1 AU using the bi-Maxwellian-based 16-moment set of transport equations. In addition to the number density, drift velocity, and parallel and perpendicular temperatures, the 16-moment equations account for the transport of both longitudinal and transverse thermal energies as well as stress. Also, using the 16-moment approximation for the distribution function and assuming plasma parameter values characteristic of the solar wind, contour plots are generated for the proton velocity distribution function. It is shown how the shape of these plots depends on various macroscopic plasma parameters.

  19. Windmill pitcher's radial neuropathy.

    PubMed

    Sinson, G; Zager, E L; Kline, D G

    1994-06-01

    The authors present two cases of severe radial nerve injury with different sites of pathology but a similar mechanism: the "windmill" pitching motion of competitive softball. Both patients required surgical intervention with neurolysis, and both improved postoperatively. The literature on related radial nerve injuries is briefly reviewed and pathophysiological mechanisms are discussed.

  20. Triple acting radial seal

    DOEpatents

    Ebert, Todd A; Carella, John A

    2012-03-13

    A triple acting radial seal used as an interstage seal assembly in a gas turbine engine, where the seal assembly includes an interstage seal support extending from a stationary inner shroud of a vane ring, the interstage seal support includes a larger annular radial inward facing groove in which an outer annular floating seal assembly is secured for radial displacement, and the outer annular floating seal assembly includes a smaller annular radial inward facing groove in which an inner annular floating seal assembly is secured also for radial displacement. A compliant seal is secured to the inner annular floating seal assembly. The outer annular floating seal assembly encapsulates the inner annular floating seal assembly which is made from a very low alpha material in order to reduce thermal stress.

  1. Velocity field measurement of a round jet using quantitative schlieren.

    PubMed

    Iffa, Emishaw D; Aziz, A Rashid A; Malik, Aamir S

    2011-02-10

    This paper utilizes the background oriented schlieren (BOS) technique to measure the velocity field of a variable density round jet. The density field of the jet is computed based on the light deflection created during the passage of light through the understudy jet. The deflection vector estimation was carried out using phase-based optical flow algorithms. The density field is further exploited to extract the axial and radial velocity vectors with the aid of continuity and energy equations. The experiment is conducted at six different jet-exit temperature values. Additional turbulence parameters, such as velocity variance and power spectral density of the vector field, are also computed. Finally, the measured velocity parameters are compared with the hot wire anemometer measurements and their correlation is displayed.

  2. Velocity field measurement of a round jet using quantitative schlieren

    SciTech Connect

    Iffa, Emishaw D.; Aziz, A. Rashid A.; Malik, Aamir S.

    2011-02-10

    This paper utilizes the background oriented schlieren (BOS) technique to measure the velocity field of a variable density round jet. The density field of the jet is computed based on the light deflection created during the passage of light through the understudy jet. The deflection vector estimation was carried out using phase-based optical flow algorithms. The density field is further exploited to extract the axial and radial velocity vectors with the aid of continuity and energy equations. The experiment is conducted at six different jet-exit temperature values. Additional turbulence parameters, such as velocity variance and power spectral density of the vector field, are also computed. Finally, the measured velocity parameters are compared with the hot wire anemometer measurements and their correlation is displayed.

  3. Radial head arthroplasty.

    PubMed

    Kleiner, M T; Ilyas, A M; Jupiter, J B

    2010-02-01

    In conclusion, radial head fractures with 3 or more fragments have a high incidence of complications when treated with ORIF including hardware failure, malunion, nonunion, and the need for re-operation. Radial head arthroplasty has demonstrated good success in the treatment of complex, comminuted radial head fractures which are not amenable to non-opeative treatment or ORIF. Success can be optimized by diligent surgical dissection, avoiding inadvertent nerve injury, placement of an appropriately sized implant, repair of associated injuries, and early protected motion. PMID:20214854

  4. Onset of radial flow in p+p collisions

    DOE PAGESBeta

    Jiang, Kun; Zhu, Yinying; Liu, Weitao; Chen, Hongfang; Li, Cheng; Ruan, Lijuan; Tang, Zebo; Xu, Zhangbu

    2015-02-23

    It has been debated for decades whether hadrons emerging from p+p collisions exhibit collective expansion. The signal of the collective motion in p+p collisions is not as clear as in heavy-ion collisions because of the low multiplicity and large fluctuation in p+p collisions. Tsallis Blast-Wave (TBW) model is a thermodynamic approach, introduced to handle the overwhelming correlation and fluctuation in the hadronic processes. We have systematically studied the identified particle spectra in p+p collisions from RHIC to LHC using TBW and found no appreciable radial flow in p+p collisions below √s = 900 GeV. At LHC higher energy of 7more » TeV in p+p collisions, the radial flow velocity achieves an average of (β) = 0.320 ± 0.005. This flow velocity is comparable to that in peripheral (40-60%) Au+Au collisions at RHIC. In addition, breaking of the identified particle spectra mT scaling was also observed at LHC from a model independent test.« less

  5. Radial head fracture - aftercare

    MedlinePlus

    Elbow fracture - radial head - aftercare ... to 2 weeks. If you have a small fracture and your bones did not move around much, ... to see a bone doctor (orthopedic surgeon). Some fractures require surgery to: Insert pins and plates to ...

  6. Radial turbine cooling

    NASA Astrophysics Data System (ADS)

    Roelke, Richard J.

    The technology of high temperature cooled radial turbines is reviewed. Aerodynamic performance considerations are described. Heat transfer and structural analysis are addressed, and in doing so the following topics are covered: cooling considerations, hot side convection, coolant side convection, and rotor mechanical analysis. Cooled rotor concepts and fabrication are described, and the following are covered in this context: internally cooled rotor, hot isostatic pressure bonded rotor, laminated rotor, split blade rotor, and the NASA radial turbine program.

  7. Radial turbine cooling

    NASA Technical Reports Server (NTRS)

    Roelke, Richard J.

    1992-01-01

    The technology of high temperature cooled radial turbines is reviewed. Aerodynamic performance considerations are described. Heat transfer and structural analysis are addressed, and in doing so the following topics are covered: cooling considerations, hot side convection, coolant side convection, and rotor mechanical analysis. Cooled rotor concepts and fabrication are described, and the following are covered in this context: internally cooled rotor, hot isostatic pressure bonded rotor, laminated rotor, split blade rotor, and the NASA radial turbine program.

  8. [Approaches to radial shaft].

    PubMed

    Bartoníček, J; Naňka, O; Tuček, M

    2015-10-01

    In the clinical practice, radial shaft may be exposed via two approaches, namely the posterolateral Thompson and volar (anterior) Henry approaches. A feared complication of both of them is the injury to the deep branch of the radial nerve. No consensus has been reached, yet, as to which of the two approaches is more beneficial for the proximal half of radius. According to our anatomical studies and clinical experience, Thompson approach is safe only in fractures of the middle and distal thirds of the radial shaft, but highly risky in fractures of its proximal third. Henry approach may be used in any fracture of the radial shaft and provides a safe exposure of the entire lateral and anterior surfaces of the radius.The Henry approach has three phases. In the first phase, incision is made along the line connecting the biceps brachii tendon and the styloid process of radius. Care must be taken not to damage the lateral cutaneous nerve of forearm.In the second phase, fascia is incised and the brachioradialis identified by the typical transition from the muscle belly to tendon and the shape of the tendon. On the lateral side, the brachioradialis lines the space with the radial artery and veins and the superficial branch of the radial nerve running at its bottom. On the medial side, the space is defined by the pronator teres in the proximal part and the flexor carpi radialis in the distal part. The superficial branch of the radial nerve is retracted together with the brachioradialis laterally, and the radial artery medially.In the third phase, the attachment of the pronator teres is identified by its typical tendon in the middle of convexity of the lateral surface of the radial shaft. The proximal half of the radius must be exposed very carefully in order not to damage the deep branch of the radial nerve. Dissection starts at the insertion of the pronator teres and proceeds proximally along its lateral border in interval between this muscle and insertion of the supinator

  9. On radial flow between parallel disks

    NASA Astrophysics Data System (ADS)

    Wee, A. Y. L.; Gorin, A.

    2015-04-01

    Approximate analytical solutions are presented for converging flow in between two parallel non rotating disks. The static pressure distribution and radial component of the velocity are developed by averaging the inertial term across the gap in between parallel disks. The predicted results from the first approximation are favourable to experimental results as well as results presented by other authors. The second approximation shows that as the fluid approaches the center, the velocity at the mid channel slows down which is due to the struggle between the inertial term and the flowrate.

  10. Radial turbine cooling

    NASA Technical Reports Server (NTRS)

    Roelke, Richard J.

    1992-01-01

    Radial turbines have been used extensively in many applications including small ground based electrical power generators, automotive engine turbochargers and aircraft auxiliary power units. In all of these applications the turbine inlet temperature is limited to a value commensurate with the material strength limitations and life requirements of uncooled metal rotors. To take advantage of all the benefits that higher temperatures offer, such as increased turbine specific power output or higher cycle thermal efficiency, requires improved high temperature materials and/or blade cooling. Extensive research is on-going to advance the material properties of high temperature superalloys as well as composite materials including ceramics. The use of ceramics with their high temperature potential and low cost is particularly appealing for radial turbines. However until these programs reach fruition the only way to make significant step increases beyond the present material temperature barriers is to cool the radial blading.

  11. Tangential velocity measurement using interferometric MTI radar

    DOEpatents

    Doerry, Armin W.; Mileshosky, Brian P.; Bickel, Douglas L.

    2006-01-03

    Radar systems use time delay measurements between a transmitted signal and its echo to calculate range to a target. Ranges that change with time cause a Doppler offset in phase and frequency of the echo. Consequently, the closing velocity between target and radar can be measured by measuring the Doppler offset of the echo. The closing velocity is also known as radial velocity, or line-of-sight velocity. Doppler frequency is measured in a pulse-Doppler radar as a linear phase shift over a set of radar pulses during some Coherent Processing Interval (CPI). An Interferometric Moving Target Indicator (MTI) radar can be used to measure the tangential velocity component of a moving target. Multiple baselines, along with the conventional radial velocity measurement, allow estimating the true 3-D velocity of a target.

  12. Radial wedge flange clamp

    DOEpatents

    Smith, Karl H.

    2002-01-01

    A radial wedge flange clamp comprising a pair of flanges each comprising a plurality of peripheral flat wedge facets having flat wedge surfaces and opposed and mating flat surfaces attached to or otherwise engaged with two elements to be joined and including a series of generally U-shaped wedge clamps each having flat wedge interior surfaces and engaging one pair of said peripheral flat wedge facets. Each of said generally U-shaped wedge clamps has in its opposing extremities apertures for the tangential insertion of bolts to apply uniform radial force to said wedge clamps when assembled about said wedge segments.

  13. Radial Nerve Tendon Transfers.

    PubMed

    Cheah, Andre Eu-Jin; Etcheson, Jennifer; Yao, Jeffrey

    2016-08-01

    Radial nerve palsy typically occurs as a result of trauma or iatrogenic injury and leads to the loss of wrist extension, finger extension, thumb extension, and a reduction in grip strength. In the absence of nerve recovery, reconstruction of motor function involves tendon transfer surgery. The most common donor tendons include the pronator teres, wrist flexors, and finger flexors. The type of tendon transfer is classified based on the donor for the extensor digitorum communis. Good outcomes have been reported for most methods of radial nerve tendon transfers as is typical for positional tendon transfers not requiring significant power. PMID:27387076

  14. CN jet velocity in Comet P/Halley

    NASA Technical Reports Server (NTRS)

    Klavetter, James J.; A'Hearn, Michael F.

    1992-01-01

    The projected expansion velocity of Comet Halley's coma is presently determined in CN jet images that were processed with a radial profile subtraction technique. It is established that the flow is approximately radial, and that the velocity can also be determined by measuring specific radial features in jets. The largest projected velocity is 1.7 +/- 0.3 km/sec, at 50,000 km from the nucleus. This is the largest expansion velocity found for this region of the Comet Halley coma. Comparisons are made with other observations and theoretical models.

  15. Radial Halbach Magnetic Bearings

    NASA Technical Reports Server (NTRS)

    Eichenberg, Dennis J.; Gallo, Christopher A.; Thompson, William K.

    2009-01-01

    Radial Halbach magnetic bearings have been investigated as part of an effort to develop increasingly reliable noncontact bearings for future high-speed rotary machines that may be used in such applications as aircraft, industrial, and land-vehicle power systems and in some medical and scientific instrumentation systems. Radial Halbach magnetic bearings are based on the same principle as that of axial Halbach magnetic bearings, differing in geometry as the names of these two types of bearings suggest. Both radial and axial Halbach magnetic bearings are passive in the sense that unlike most other magnetic bearings that have been developed in recent years, they effect stable magnetic levitation without need for complex active control. Axial Halbach magnetic bearings were described in Axial Halbach Magnetic Bearings (LEW-18066-1), NASA Tech Briefs, Vol. 32, No. 7 (July 2008), page 85. In the remainder of this article, the description of the principle of operation from the cited prior article is recapitulated and updated to incorporate the present radial geometry. In simplest terms, the basic principle of levitation in an axial or radial Halbach magnetic bearing is that of the repulsive electromagnetic force between (1) a moving permanent magnet and (2) an electric current induced in a stationary electrical conductor by the motion of the magnetic field. An axial or radial Halbach bearing includes multiple permanent magnets arranged in a Halbach array ("Halbach array" is defined below) in a rotor and multiple conductors in the form of wire coils in a stator, all arranged so the rotary motion produces an axial or radial repulsion that is sufficient to levitate the rotor. A basic Halbach array (see Figure 1) consists of a row of permanent magnets, each oriented so that its magnetic field is at a right angle to that of the adjacent magnet, and the right-angle turns are sequenced so as to maximize the magnitude of the magnetic flux density on one side of the row while

  16. Radial velocity observations of the sun at night

    NASA Technical Reports Server (NTRS)

    Mcmillan, R. S.; Moore, T. L.; Perry, M. L.; Smith, P. H.

    1993-01-01

    The ability to detect planets orbiting stars has been evaluated through solar-spectrum Doppler shift measurements for 5 years, using the sunlit surface of the moon to furnish nighttime access to the solar spectrum integrated over the solar disk as though the sun were being observed at stellar distance. These lunar observations have indicated that the Doppler shift of the integrated solar photosphere disk in violet absorption lines has varied less that +/- 4 m/sec over the 1987-1992 interval studied.

  17. Variable stator radial turbine

    NASA Technical Reports Server (NTRS)

    Rogo, C.; Hajek, T.; Chen, A. G.

    1984-01-01

    A radial turbine stage with a variable area nozzle was investigated. A high work capacity turbine design with a known high performance base was modified to accept a fixed vane stagger angle moveable sidewall nozzle. The nozzle area was varied by moving the forward and rearward sidewalls. Diffusing and accelerating rotor inlet ramps were evaluated in combinations with hub and shroud rotor exit rings. Performance of contoured sidewalls and the location of the sidewall split line with respect to the rotor inlet was compared to the baseline. Performance and rotor exit survey data are presented for 31 different geometries. Detail survey data at the nozzle exit are given in contour plot format for five configurations. A data base is provided for a variable geometry concept that is a viable alternative to the more common pivoted vane variable geometry radial turbine.

  18. Axonemal radial spokes

    PubMed Central

    Pigino, Gaia; Ishikawa, Takashi

    2012-01-01

    The radial spoke (RS) is a complex of at least 23 proteins that works as a mechanochemical transducer between the central‐pair apparatus and the peripheral microtubule doublets in eukaryotic flagella and motile cilia. The RS contributes to the regulation of the activity of dynein motors, and thus to flagellar motility. Despite numerous biochemical, physiological and structural studies, the mechanism of the function of the radial spoke remains unclear. Detailed knowledge of the 3D structure of the RS protein complex is needed in order to understand how RS regulates dynein activity. Here we review the most important findings on the structure of the RS, including results of our recent cryo‐electron tomographic analysis of the RS protein complex. PMID:22754630

  19. Radial pressure flange seal

    DOEpatents

    Batzer, Thomas H.; Call, Wayne R.

    1989-01-01

    This invention provides an all metal seal for vacuum or pressure vessels or systems. This invention does not use gaskets. The invention uses a flange which fits into a matching groove. Fluid pressure is applied in a chamber in the flange causing at least one of the flange walls to radially press against a side of the groove creating the seal between the flange wall and the groove side.

  20. DESIGN ANALYSIS OF RADIAL INFLOW TURBINES

    NASA Technical Reports Server (NTRS)

    Glassman, A. J.

    1994-01-01

    This program performs a velocity-diagram analysis required for determining geometry and estimating performance for radial-inflow turbines. Input design requirements are power, mass flow rate, inlet temperature and pressure, and rotative rate. The design variables include stator-exit angle, rotor-exit-tip to rotor-inlet radius ratio, rotor-exit-hub to tip radius ratio, and the magnitude and radial distribution of rotor-exit tangential velocity. The program output includes diameters, total and static efficiences, all absolute and relative temperatures, pressures, and velocities, and flow angles at stator inlet, stator exit, rotor inlet, and rotor exit. Losses accounted for in this program by the internal loss model are three-dimensional (profile plus end wall) viscous losses in the stator and the rotor, the disk-friction loss on the back side of the rotor, the loss due to the clearance between the rotor tip and the outer casing, and the exit velocity loss. The flow analysis is one-dimensional at the stator inlet, stator exit, and rotor inlet, each of these calculation stations being at a constant radius. At the rotor exit where there is a variation in flow-field radius, an axisymmetric two-dimensional analysis is made using constant height sectors. Simple radial equilibrium is used to establish the static pressure gradient at the rotor exit. This program is written in FORTRAN V and has been implemented on a UNIVAC 1100 series computer with a memory requirement of approximately 22K of 36 bit words.

  1. Radially inhomogeneous bounded plasmas

    NASA Astrophysics Data System (ADS)

    Zakeri-Khatir, H.; Aghamir, F. M.

    2016-07-01

    On the basis of kinetic theory along with self-consistent field equations, the expressions for dielectric tensor of radially inhomogeneous magnetized plasma columns are obtained. The study of dielectric tensor characteristics allows the accurate analysis of the inhomogeneous properties, beyond limitations that exist in the conventional method. Through the Bessel-Fourier transformation, the localized form of material equations in a radially inhomogeneous medium are obtained. In order to verify the integrity of the model and reveal the effect of inhomogeneity, a special case of a cylindrical plasma waveguide completely filled with inhomogeneous magnetized cold plasma was considered. The dispersion relation curves for four families of electromagnetic (EH and HE) and electrostatic (SC and C) modes are obtained and compared with the findings of the conventional model. The numerical analysis indicates that the inhomogeneity effect leads to coupling of electromagnetic and electrostatic modes each having different radial eigen numbers. The study also reveals that the electrostatic modes are more sensitive to inhomogeneous effects than the electromagnetic modes.

  2. Radially inhomogeneous bounded plasmas

    NASA Astrophysics Data System (ADS)

    Zakeri-Khatir, H.; Aghamir, F. M.

    2016-07-01

    On the basis of kinetic theory along with self-consistent field equations, the expressions for dielectric tensor of radially inhomogeneous magnetized plasma columns are obtained. The study of dielectric tensor characteristics allows the accurate analysis of the inhomogeneous properties, beyond limitations that exist in the conventional method. Through the Bessel–Fourier transformation, the localized form of material equations in a radially inhomogeneous medium are obtained. In order to verify the integrity of the model and reveal the effect of inhomogeneity, a special case of a cylindrical plasma waveguide completely filled with inhomogeneous magnetized cold plasma was considered. The dispersion relation curves for four families of electromagnetic (EH and HE) and electrostatic (SC and C) modes are obtained and compared with the findings of the conventional model. The numerical analysis indicates that the inhomogeneity effect leads to coupling of electromagnetic and electrostatic modes each having different radial eigen numbers. The study also reveals that the electrostatic modes are more sensitive to inhomogeneous effects than the electromagnetic modes.

  3. Radial Field Piezoelectric Diaphragms

    NASA Technical Reports Server (NTRS)

    Bryant, R. G.; Effinger, R. T., IV; Copeland, B. M., Jr.

    2002-01-01

    A series of active piezoelectric diaphragms were fabricated and patterned with several geometrically defined Inter-Circulating Electrodes "ICE" and Interdigitated Ring Electrodes "ICE". When a voltage potential is applied to the electrodes, the result is a radially distributed electric field that mechanically strains the piezoceramic along the Z-axis (perpendicular to the applied electric field). Unlike other piezoelectric bender actuators, these Radial Field Diaphragms (RFDs) strain concentrically yet afford high displacements (several times that of the equivalent Unimorph) while maintaining a constant circumference. One of the more intriguing aspects is that the radial strain field reverses itself along the radius of the RFD while the tangential strain remains relatively constant. The result is a Z-deflection that has a conical profile. This paper covers the fabrication and characterization of the 5 cm. (2 in.) diaphragms as a function of poling field strength, ceramic thickness, electrode type and line spacing, as well as the surface topography, the resulting strain field and displacement as a function of applied voltage at low frequencies. The unique features of these RFDs include the ability to be clamped about their perimeter with little or no change in displacement, the environmentally insulated packaging, and a highly repeatable fabrication process that uses commodity materials.

  4. Antiproton compression and radial measurements

    SciTech Connect

    Andresen, G. B.; Bowe, P. D.; Hangst, J. S.; Bertsche, W.; Butler, E.; Charlton, M.; Humphries, A. J.; Jenkins, M. J.; Joergensen, L. V.; Madsen, N.; Werf, D. P. van der; Bray, C. C.; Chapman, S.; Fajans, J.; Povilus, A.; Wurtele, J. S.; Cesar, C. L.; Lambo, R.; Silveira, D. M.; Fujiwara, M. C.

    2008-08-08

    Control of the radial profile of trapped antiproton clouds is critical to trapping antihydrogen. We report detailed measurements of the radial manipulation of antiproton clouds, including areal density compressions by factors as large as ten, achieved by manipulating spatially overlapped electron plasmas. We show detailed measurements of the near-axis antiproton radial profile, and its relation to that of the electron plasma. We also measure the outer radial profile by ejecting antiprotons to the trap wall using an octupole magnet.

  5. Radial spoke proteins of Chlamydomonas flagella

    PubMed Central

    Yang, Pinfen; Diener, Dennis R.; Yang, Chun; Kohno, Takahiro; Pazour, Gregory J.; Dienes, Jennifer M.; Agrin, Nathan S.; King, Stephen M.; Sale, Winfield S.; Kamiya, Ritsu; Rosenbaum, Joel L.; Witman, George B.

    2007-01-01

    Summary The radial spoke is a ubiquitous component of ‘9+2’ cilia and flagella, and plays an essential role in the control of dynein arm activity by relaying signals from the central pair of microtubules to the arms. The Chlamydomonas reinhardtii radial spoke contains at least 23 proteins, only 8 of which have been characterized at the molecular level. Here, we use mass spectrometry to identify 10 additional radial spoke proteins. Many of the newly identified proteins in the spoke stalk are predicted to contain domains associated with signal transduction, including Ca2+-, AKAP- and nucleotide-binding domains. This suggests that the spoke stalk is both a scaffold for signaling molecules and itself a transducer of signals. Moreover, in addition to the recently described HSP40 family member, a second spoke stalk protein is predicted to be a molecular chaperone, implying that there is a sophisticated mechanism for the assembly of this large complex. Among the 18 spoke proteins identified to date, at least 12 have apparent homologs in humans, indicating that the radial spoke has been conserved throughout evolution. The human genes encoding these proteins are candidates for causing primary ciliary dyskinesia, a severe inherited disease involving missing or defective axonemal structures, including the radial spokes. PMID:16507594

  6. Radial polar histogram: obstacle avoidance and path planning for robotic cognition and motion control

    NASA Astrophysics Data System (ADS)

    Wang, Po-Jen; Keyawa, Nicholas R.; Euler, Craig

    2012-01-01

    In order to achieve highly accurate motion control and path planning for a mobile robot, an obstacle avoidance algorithm that provided a desired instantaneous turning radius and velocity was generated. This type of obstacle avoidance algorithm, which has been implemented in California State University Northridge's Intelligent Ground Vehicle (IGV), is known as Radial Polar Histogram (RPH). The RPH algorithm utilizes raw data in the form of a polar histogram that is read from a Laser Range Finder (LRF) and a camera. A desired open block is determined from the raw data utilizing a navigational heading and an elliptical approximation. The left and right most radii are determined from the calculated edges of the open block and provide the range of possible radial paths the IGV can travel through. In addition, the calculated obstacle edge positions allow the IGV to recognize complex obstacle arrangements and to slow down accordingly. A radial path optimization function calculates the best radial path between the left and right most radii and is sent to motion control for speed determination. Overall, the RPH algorithm allows the IGV to autonomously travel at average speeds of 3mph while avoiding all obstacles, with a processing time of approximately 10ms.

  7. Radial inflow turbine study

    NASA Astrophysics Data System (ADS)

    Hamid, S.; Elder, R. L.

    1992-03-01

    The radial inflow turbine is a primary component used both in small gas turbines and turbochargers. Better understanding of the flow processes occurring within the small passages of the machine could well result in the improved design of units. As most of the detailed aerodynamics is still ill-defined, a joint research project with the objective of improving our understanding has been instigated by Cranfield, the US Army and Turbomach (San Diego). This document gives the seventh report on the project and describes progress and measurements taken.

  8. Harvesting the radial artery

    PubMed Central

    Osterday, Robert M.; Brodman, Richard F.

    2013-01-01

    The radial artery (RA) has emerged as an important arterial graft for coronary bypass surgery. With improving five-year patency rates and increasing uptake, great attention has been focused on the optimal conduit harvesting technique. We herein present our approach to RA harvesting. Prerequisites of a successful harvest include adherence to important anatomical landmarks, protection of the sensory innervation to the volar forearm, and meticulous handling of the RA branches. Regardless of the harvesting methodology chosen, adherence to a “no-touch” technique will optimize the patency and durability of the RA conduit. PMID:23977633

  9. Radial cutting torch

    SciTech Connect

    Robertson, M.C.

    1997-01-08

    The project`s aim is to complete development of the Radial Cutting Torch, a pyrotechnic cutter, for use in all downhole tubular cutting operations in the petroleum industry. Project objectives are to redesign and pressure test nozzle seals to increase product quality, reliability, and manufacturability; improve the mechanical anchor to increase its temperature tolerance and its ability to function in a wider variety of wellbore fluids; and redesign and pressure test the RCT nozzle for operation at pressures from 10 to 20 ksi. The proposal work statement is included in the statement of work for the grant via this reference.

  10. Radial Reflection diffraction tomorgraphy

    DOEpatents

    Lehman, Sean K

    2013-11-19

    A wave-based tomographic imaging method and apparatus based upon one or more rotating radially outward oriented transmitting and receiving elements have been developed for non-destructive evaluation. At successive angular locations at a fixed radius, a predetermined transmitting element can launch a primary field and one or more predetermined receiving elements can collect the backscattered field in a "pitch/catch" operation. A Hilbert space inverse wave (HSIW) algorithm can construct images of the received scattered energy waves using operating modes chosen for a particular application. Applications include, improved intravascular imaging, bore hole tomography, and non-destructive evaluation (NDE) of parts having existing access holes.

  11. Radial reflection diffraction tomography

    DOEpatents

    Lehman, Sean K.

    2012-12-18

    A wave-based tomographic imaging method and apparatus based upon one or more rotating radially outward oriented transmitting and receiving elements have been developed for non-destructive evaluation. At successive angular locations at a fixed radius, a predetermined transmitting element can launch a primary field and one or more predetermined receiving elements can collect the backscattered field in a "pitch/catch" operation. A Hilbert space inverse wave (HSIW) algorithm can construct images of the received scattered energy waves using operating modes chosen for a particular application. Applications include, improved intravascular imaging, bore hole tomography, and non-destructive evaluation (NDE) of parts having existing access holes.

  12. Reconstruction for Type IV Radial Polydactyly.

    PubMed

    Wall, Lindley B; Goldfarb, Charles A

    2015-09-01

    Type IV radial polydactyly represents a thumb with an extra proximal and distal phalanx. Assessment of the thumb for surgical reconstruction includes observing thumb function, evaluating thumb size and stability, and assessing the first web space. Reconstruction includes excision of the smaller thumb, typically the radial thumb, and re-creating thumb stability and alignment by addressing tendon insertion and joint orientation. Although surgical results are satisfying and complications are uncommon, additional surgical intervention may be required over time owing to thumb malalignment or instability.

  13. Radial flow pulse jet mixer

    SciTech Connect

    VanOsdol, John G.

    2013-06-25

    The disclosure provides a pulse jet mixing vessel for mixing a plurality of solid particles. The pulse jet mixing vessel is comprised of a sludge basin, a flow surface surrounding the sludge basin, and a downcoming flow annulus between the flow surface and an inner shroud. The pulse jet mixing vessel is additionally comprised of an upper vessel pressurization volume in fluid communication with the downcoming flow annulus, and an inner shroud surge volume separated from the downcoming flow annulus by the inner shroud. When the solid particles are resting on the sludge basin and a fluid such as water is atop the particles and extending into the downcoming flow annulus and the inner shroud surge volume, mixing occurs by pressurization of the upper vessel pressurization volume, generating an inward radial flow over the flow surface and an upwash jet at the center of the sludge basin.

  14. Porcine radial artery decellularization by high hydrostatic pressure.

    PubMed

    Negishi, Jun; Funamoto, Seiichi; Kimura, Tsuyoshi; Nam, Kwangoo; Higami, Tetsuya; Kishida, Akio

    2015-11-01

    Many types of decellularized tissues have been studied and some have been commercially used in clinics. In this study, small-diameter vascular grafts were made using HHP to decellularize porcine radial arteries. One decellularization method, high hydrostatic pressure (HHP), has been used to prepare the decellularized porcine tissues. Low-temperature treatment was effective in preserving collagen and collagen structures in decellularized porcine carotid arteries. The collagen and elastin structures and mechanical properties of HHP-decellularized radial arteries were similar to those of untreated radial arteries. Xenogeneic transplantation (into rats) was performed using HHP-decellularized radial arteries and an untreated porcine radial artery. Two weeks after transplantation into rat carotid arteries, the HHP-decellularized radial arteries were patent and without thrombosis. In addition, the luminal surface of each decellularized artery was covered by recipient endothelial cells and the arterial medium was fully infiltrated with recipient cells.

  15. A STAR IN THE M31 GIANT STREAM: THE HIGHEST NEGATIVE STELLAR VELOCITY KNOWN

    SciTech Connect

    Caldwell, Nelson; Kenyon, Scott J.; Morrison, Heather; Harding, Paul; Schiavon, Ricardo; Rose, James A. E-mail: kenyon@cfa.harvard.edu E-mail: paul.harding@case.edu E-mail: jim@physics.unc.edu

    2010-02-15

    We report on a single star, B030D, observed as part of a large survey of objects in M31, which has the unusual radial velocity of -780 km s{sup -1}. Based on details of its spectrum, we find that the star is an F supergiant, with a circumstellar shell. The evolutionary status of the star could be one of a post-main-sequence close binary, a symbiotic nova, or less likely, a post-asymptotic giant branch star, which additional observations could help sort out. Membership of the star in the Andromeda Giant Stream can explain its highly negative velocity.

  16. Reelin signaling directly affects radial glia morphology and biochemical maturation.

    PubMed

    Hartfuss, Eva; Förster, Eckart; Bock, Hans H; Hack, Michael A; Leprince, Pierre; Luque, Juan M; Herz, Joachim; Frotscher, Michael; Götz, Magdalena

    2003-10-01

    Radial glial cells are characterized, besides their astroglial properties, by long radial processes extending from the ventricular zone to the pial surface, a crucial feature for the radial migration of neurons. The molecular signals that regulate this characteristic morphology, however, are largely unknown. We show an important role of the secreted molecule reelin for the establishment of radial glia processes. We describe a significant reduction in ventricular zone cells with long radial processes in the absence of reelin in the cortex of reeler mutant mice. These defects were correlated to a decrease in the content of brain lipid-binding protein (Blbp) and were detected exclusively in the cerebral cortex, but not in the basal ganglia of reeler mice. Conversely, reelin addition in vitro increased the Blbp content and process extension of radial glia from the cortex, but not the basal ganglia. Isolation of radial glia by fluorescent-activated cell sorting showed that these effects are due to direct signaling of reelin to radial glial cells. We could further demonstrate that this signaling requires Dab1, as the increase in Blbp upon reelin addition failed to occur in Dab1-/- mice. Taken together, these results unravel a novel role of reelin signaling to radial glial cells that is crucial for the regulation of their Blbp content and characteristic morphology in a region-specific manner.

  17. Sodium Velocity Maps on Mercury

    NASA Technical Reports Server (NTRS)

    Potter, A. E.; Killen, R. M.

    2011-01-01

    The objective of the current work was to measure two-dimensional maps of sodium velocities on the Mercury surface and examine the maps for evidence of sources or sinks of sodium on the surface. The McMath-Pierce Solar Telescope and the Stellar Spectrograph were used to measure Mercury spectra that were sampled at 7 milliAngstrom intervals. Observations were made each day during the period October 5-9, 2010. The dawn terminator was in view during that time. The velocity shift of the centroid of the Mercury emission line was measured relative to the solar sodium Fraunhofer line corrected for radial velocity of the Earth. The difference between the observed and calculated velocity shift was taken to be the velocity vector of the sodium relative to Earth. For each position of the spectrograph slit, a line of velocities across the planet was measured. Then, the spectrograph slit was stepped over the surface of Mercury at 1 arc second intervals. The position of Mercury was stabilized by an adaptive optics system. The collection of lines were assembled into an images of surface reflection, sodium emission intensities, and Earthward velocities over the surface of Mercury. The velocity map shows patches of higher velocity in the southern hemisphere, suggesting the existence of sodium sources there. The peak earthward velocity occurs in the equatorial region, and extends to the terminator. Since this was a dawn terminator, this might be an indication of dawn evaporation of sodium. Leblanc et al. (2008) have published a velocity map that is similar.

  18. Radial cold trap

    DOEpatents

    Grundy, B.R.

    1981-09-29

    The radial cold trap comprises a housing having a plurality of mesh bands disposed therein. The mesh bands comprise concentrically arranged bands of mesh with the mesh specific surface area of each band increasing from the outermost mesh band to the innermost mesh band. An inlet nozzle is attached to the outside section of the housing while an outlet nozzle is attached to the inner portion of the housing so as to be concentrically connected to the innermost mesh band. An inlet baffle having orifices therein may be disposed around the outermost mesh band and within the housing for directing the flow of the fluid from the inlet nozzle to the outermost mesh band in a uniform manner. The flow of fluid passes through each consecutive mesh band and into the outlet nozzle. The circular pattern of the symmetrically arranged mesh packing allows for better utilization of the entire cold trap volume. 2 figs.

  19. Radial cold trap

    DOEpatents

    Grundy, Brian R.

    1981-01-01

    The radial cold trap comprises a housing having a plurality of mesh bands disposed therein. The mesh bands comprise concentrically arranged bands of mesh with the mesh specific surface area of each band increasing from the outermost mesh band to the innermost mesh band. An inlet nozzle is attached to the outside section of the housing while an outlet nozzle is attached to the inner portion of the housing so as to be concentrically connected to the innermost mesh band. An inlet baffle having orifices therein may be disposed around the outermost mesh band and within the housing for directing the flow of the fluid from the inlet nozzle to the outermost mesh band in a uniform manner. The flow of fluid passes through each consecutive mesh band and into the outlet nozzle. The circular pattern of the symmetrically arranged mesh packing allows for better utilization of the entire cold trap volume.

  20. Simulation of wave propagation in boreholes and radial profiling of formation elastic parameters

    NASA Astrophysics Data System (ADS)

    Chi, Shihong

    numerical method is stable and efficient for the simulation of wave propagation in boreholes surrounded by complex invasion zones. Additional tests of the inversion algorithm are performed on array waveform data acquired in a low-porosity gas field. Mud-filtrate invasion effects are not measurable on the estimated P- and S-wave velocities for depths of invasion around 2--3 borehole diameters. Acoustic log corrections performed with the Blot-Gassmann fluid substitution model can only be used for the case of deep invasion. The inversion examples indicate that physically consistent radial profiles of formation density and P- and S-wave velocities can be reconstructed from array waveform data.

  1. The Spin Effect on Planetary Radial Velocimetry of Exoplanets

    NASA Astrophysics Data System (ADS)

    Kawahara, Hajime

    2012-11-01

    We consider the effect of planetary spin on the planetary radial velocity (PRV) in dayside spectra of exoplanets. To understand the spin effect qualitatively, we derive an analytic formula of the intensity-weighted radial velocity from the planetary surface on the following assumptions: (1) constant and solid rotation without precession, (2) stable and uniform distribution of molecules/atoms, (3) emission models from the dayside hemisphere, and (4) a circular orbit. On these assumptions, we find that the curve of the PRV is distorted by the planetary spin and this anomaly is characterized by the spin radial velocity at the equator and a projected angle on a celestial plane between the spin axis and the axis of orbital motion λ p in a manner analogous to the Rossiter-McLaughlin effect. The latter can constrain the planetary obliquity. Creating mock PRV data with 3 km s-1 accuracy, we demonstrate how λ p and the spin radial velocity at the equator are estimated. We find that the stringent constraint of eccentricity is crucial to detect the spin effect. Though our formula is still qualitative, we conclude that the PRV in the dayside spectra will be a powerful means for constraining the planetary spin.

  2. THE SPIN EFFECT ON PLANETARY RADIAL VELOCIMETRY OF EXOPLANETS

    SciTech Connect

    Kawahara, Hajime

    2012-11-20

    We consider the effect of planetary spin on the planetary radial velocity (PRV) in dayside spectra of exoplanets. To understand the spin effect qualitatively, we derive an analytic formula of the intensity-weighted radial velocity from the planetary surface on the following assumptions: (1) constant and solid rotation without precession, (2) stable and uniform distribution of molecules/atoms, (3) emission models from the dayside hemisphere, and (4) a circular orbit. On these assumptions, we find that the curve of the PRV is distorted by the planetary spin and this anomaly is characterized by the spin radial velocity at the equator and a projected angle on a celestial plane between the spin axis and the axis of orbital motion {lambda}{sub p} in a manner analogous to the Rossiter-McLaughlin effect. The latter can constrain the planetary obliquity. Creating mock PRV data with 3 km s{sup -1} accuracy, we demonstrate how {lambda}{sub p} and the spin radial velocity at the equator are estimated. We find that the stringent constraint of eccentricity is crucial to detect the spin effect. Though our formula is still qualitative, we conclude that the PRV in the dayside spectra will be a powerful means for constraining the planetary spin.

  3. Sensitivity of tropical cyclone characteristics to the radial distribution of sea surface temperature

    NASA Astrophysics Data System (ADS)

    Rai, Deepika; Pattnaik, S.; Rajesh, P. V.

    2016-06-01

    Sea Surface Temperature (SST) is crucial for the development and maintenance of a tropical cyclone (TC) particularly below the storm core region. However, storm data below the core region is the most difficult to obtain, hence it is not clear yet that how sensitive the radial distribution of the SST impact the storm characteristic features such as its inner-core structures, translational speed, track, rainfall and intensity particularly over the Bay of Bengal. To explore the effects of radial SST distribution on the TC characteristics, a series of numerical experiments were carried out by modifying the SST at different radial extents using two-way interactive, triply-nested, nonhydrostatic Advanced Weather Research and Forecast (WRF-ARW) model. It is found that not only the SST under the eyewall (core region) contribute significantly to modulate storm track, translational speed and intensity, but also those outside the eyewall region (i.e., 2-2.5 times the radius of maximum wind (RMW)) play a vital role in defining the storm's characteristics and structure. Out of all the simulated experiments, storm where the positive radial change of SST inducted within the 75 km of the storm core (i.e., P75) produced the strongest storm. In addition, N300 (negative radial changes at 300 km) produced the weakest storm. Further, it is found that SST, stronger within 2-2.5 times of the RMW for P75 experiment, plays a dominant role in maintaining 10 m wind speed (WS 10), surface entropy flux (SEF) and upward vertical velocity ( w) within the eyewall with warmer air temperature (T) and equivalent potential temperature ( 𝜃 e) within the storm's eye compared to other experiments.

  4. General relativistic effects in galactic rotation velocity profiles

    NASA Astrophysics Data System (ADS)

    Cisneros, Sophia

    2008-10-01

    The anomalously high galactic rotation velocities deduced from spectroscopic observations have motivated the conjecture of additional Dark Matter. Here we investigate to what extent this picture may be impacted by general relativistic effects. Previous work involving General Relativity has used linearized field equations to arrive at estimates of wavelength shifts arising from spin induced curvature. We show here that, using the fully contravariant 3+1 dimensional wave equation (the D'Alembertian for a Kerr Metric), non-trivial results for observed velocities can be obtained. These velocities are much higher than those obtained from the linearized equations. The Kerr rotation curve is derived from first principles. The wavelength shifts are then weighted by an empirical factor which accounts for difference in curvature of the originating galaxy and the Milky Way. The resulting apparent radial dependence of the velocity is much flatter than obtained in the Keplerian case, which opens the possibility that, for our test galaxy(M33), we have correct estimates of (luminous) matter on the exterior edges, but have only underestimated the mass at the center. This result suggests that general relativistic effects mitigate, or may possibly even obviate the need to invoke the presence of Dark Matter in order to explain the observed apparent velocity profiles. All rotation curves presented are computed with data graciously provided by E.Corbelli and R.Walterbos for M33, taken in the wavelength band of H/alpha.

  5. Control of low-frequency plasma instabilities by a nonuniform radial electric field

    SciTech Connect

    Komori, A.; Watanabe, K.; Kawai, Y.

    1988-01-01

    Flute instability of a magnetoplasma is generated and controlled experimentally by a nonuniform weak radial electric field. Six concentric electrodes, biased separately, are used to change the radial electric field. The instability, which is different from the velocity shear flute instability, is observed in a plasma with well-type potential and hill-type density profiles.

  6. Description of secondary flows in radial flow machines

    NASA Astrophysics Data System (ADS)

    van den Braembussche, R.

    Detailed measurements by Moore (1973) have revealed that the jet wake formation in radial flow turbomachines is essentially a three-dimensional phenomenon governed by streamwise vorticity; the boundary layers in question make an important contribution to the behavior of low energy fluid transport to a wake region. Secondary flows also contribute to distorted diffuser inlet conditions, which in turn are responsible for important downstream perturbations. Attention is presently given to blade pressure and suction side boundary layers, secondary flow velocity vectors, meridional velocity variation, secondary flow velocity vectors, and secondary flows in diffusers.

  7. Radial flow heat exchanger

    DOEpatents

    Valenzuela, Javier

    2001-01-01

    A radial flow heat exchanger (20) having a plurality of first passages (24) for transporting a first fluid (25) and a plurality of second passages (26) for transporting a second fluid (27). The first and second passages are arranged in stacked, alternating relationship, are separated from one another by relatively thin plates (30) and (32), and surround a central axis (22). The thickness of the first and second passages are selected so that the first and second fluids, respectively, are transported with laminar flow through the passages. To enhance thermal energy transfer between first and second passages, the latter are arranged so each first passage is in thermal communication with an associated second passage along substantially its entire length, and vice versa with respect to the second passages. The heat exchangers may be stacked to achieve a modular heat exchange assembly (300). Certain heat exchangers in the assembly may be designed slightly differently than other heat exchangers to address changes in fluid properties during transport through the heat exchanger, so as to enhance overall thermal effectiveness of the assembly.

  8. Radial distribution function in polymers

    NASA Astrophysics Data System (ADS)

    Przygocki, Wladyslaw

    1997-02-01

    Radial distribution function is a very useful tool for determination of the polymer structure. The connection between the scattered X-ray intensity and radial distribution function is presented. Some examples of RDF for polyethylene and for poly(ethylene terephtalate).

  9. A technique for generating shear waves in cylindrical shells under radial impact

    NASA Technical Reports Server (NTRS)

    Blum, A.; Mortimer, R. W.; Rose, J. L.

    1974-01-01

    Experimental techniques are developed to study and measure the shear-wave velocity in an aluminum cylindrical shell subjected to a radial impact. The radial impact is obtained by exploding an electrical detonator inserted in plastic plugs mounted on the end of the shell. Strain gages, mounted on the outside surface of the shell at various axial locations, are used to obtain oscilloscope traces from which the shear-wave velocity can be calculated.

  10. The effect of radial migration on galactic disks

    SciTech Connect

    Vera-Ciro, Carlos; D'Onghia, Elena; Navarro, Julio; Abadi, Mario

    2014-10-20

    We study the radial migration of stars driven by recurring multi-arm spiral features in an exponential disk embedded in a dark matter halo. The spiral perturbations redistribute angular momentum within the disk and lead to substantial radial displacements of individual stars, in a manner that largely preserves the circularity of their orbits and that results, after 5 Gyr (∼40 full rotations at the disk scale length), in little radial heating and no appreciable changes to the vertical or radial structure of the disk. Our results clarify a number of issues related to the spatial distribution and kinematics of migrators. In particular, we find that migrators are a heavily biased subset of stars with preferentially low vertical velocity dispersions. This 'provenance bias' for migrators is not surprising in hindsight, for stars with small vertical excursions spend more time near the disk plane, and thus respond more readily to non-axisymmetric perturbations. We also find that the vertical velocity dispersion of outward migrators always decreases, whereas the opposite holds for inward migrators. To first order, newly arrived migrators simply replace stars that have migrated off to other radii, thus inheriting the vertical bias of the latter. Extreme migrators might therefore be recognized, if present, by the unexpectedly small amplitude of their vertical excursions. Our results show that migration, understood as changes in angular momentum that preserve circularity, can strongly affect the thin disk, but cast doubts on models that envision the Galactic thick disk as a relic of radial migration.

  11. Time-and-space resolved comparison of plasma expansion velocities in high-power diodes with velvet cathodes

    NASA Astrophysics Data System (ADS)

    Yang, Jie; Shu, Ting; Fan, Yuwei

    2013-01-01

    Time-and-space resolved comparison of the expansion velocities of plasmas in the planar diode with cathodes made of carbon velvet and polymer velvet has been performed. The diode was powered by a 200 kV, 110 ns pulse, and the peak current density was nearly 477 A/cm2. A four-channel high speed framing camera (HSFC) was used to observe the formation and subsequent movement of the cathode plasmas. More accurate and valuable information about the two-dimensional (radial and axial) velocity components of the cathode plasmas was also acquired by utilizing the digital image processing methods. Additionally, the perveance model based on the Child-Langmuir law was used to calculate the expansion velocities of the diode plasmas from voltage and current profiles. Results from the two diagnostics were compared. Comparing the average values of the radial and axial velocity components indicated that the former was much larger than the latter during the initial period of the current. It was also found that the radial velocity of the carbon velvet cathode (190 cm/μs) was much larger than that (90 cm/μs) of the polymer velvet cathode. Moreover, the average values of both the radial and axial velocity components of the carbon velvet cathode were typically in the range of 2.5 ± 1.5 cm/μs, which were smaller than that of the polymer velvet cathode during the current flattop. These results, together with the comparison of calculated values from the perveance model, indicated that the diode with carbon velvet cathode was more robust as compared with the polymer velvet cathode for the same electron current densities.

  12. Time-and-space resolved comparison of plasma expansion velocities in high-power diodes with velvet cathodes

    SciTech Connect

    Yang Jie; Shu Ting; Fan Yuwei

    2013-01-28

    Time-and-space resolved comparison of the expansion velocities of plasmas in the planar diode with cathodes made of carbon velvet and polymer velvet has been performed. The diode was powered by a 200 kV, 110 ns pulse, and the peak current density was nearly 477 A/cm{sup 2}. A four-channel high speed framing camera (HSFC) was used to observe the formation and subsequent movement of the cathode plasmas. More accurate and valuable information about the two-dimensional (radial and axial) velocity components of the cathode plasmas was also acquired by utilizing the digital image processing methods. Additionally, the perveance model based on the Child-Langmuir law was used to calculate the expansion velocities of the diode plasmas from voltage and current profiles. Results from the two diagnostics were compared. Comparing the average values of the radial and axial velocity components indicated that the former was much larger than the latter during the initial period of the current. It was also found that the radial velocity of the carbon velvet cathode (190 cm/{mu}s) was much larger than that (90 cm/{mu}s) of the polymer velvet cathode. Moreover, the average values of both the radial and axial velocity components of the carbon velvet cathode were typically in the range of 2.5 {+-} 1.5 cm/{mu}s, which were smaller than that of the polymer velvet cathode during the current flattop. These results, together with the comparison of calculated values from the perveance model, indicated that the diode with carbon velvet cathode was more robust as compared with the polymer velvet cathode for the same electron current densities.

  13. Impact of Diabetes Mellitus on Radial and Ulnar Arterial Vasoreactivity after Radial Artery Cannulation: A Randomized Controlled trial

    PubMed Central

    Kim, Eun Jung; Soh, Sarah; Kim, So Yeon; Kil, Hae Keum; Lee, Jae Hoon; Kim, Jeong Min; Kim, Tae Whan; Koo, Bon-Nyeo

    2016-01-01

    Background: Endothelial dysfunction associated with diabetes mellitus (DM) may influence arterial vasoreactivity after arterial stimulus, such as cannulation, and cause changes in diameter and blood flow. Despite the frequent use of arterial cannulation during anesthesia and critical care, little information is available regarding vasoreactivity of the radial and ulnar arteries and its influence on underlying DM. Methods: Forty non-DM and 40 DM patients, who required arterial cannulation during general anesthesia, were enrolled. Using duplex Doppler ultrasonography, we measured the patients' arterial diameter, peak systolic velocity, end-diastolic velocity, resistance index, and mean volume flow of both arteries at five different time points. Results: After radial artery cannulation, ulnar arterial diameter and blood flow did not significantly increase in DM group, as they did in non-DM group. Ulnar arterial resistance index significantly increased in both groups, but the degree of decrease in DM group was significantly less than non-DM. Conclusion: Ulnar artery's ability to increase blood flow for compensating the sudden reduction of radial arterial flow in DM patients was significantly less than that in non-DM patients under general anesthesia. Such attenuated vasoreactivity of ulnar artery to compensate the reduced radial arterial flow may have to be considered in radial arterial cannulation for DM patients. PMID:27648000

  14. Radial Motions in Disk Stars: Ellipticity or Secular Flows?

    NASA Astrophysics Data System (ADS)

    López-Corredoira, M.; González-Fernández, C.

    2016-06-01

    Average stellar orbits of the Galactic disk may have some small intrinsic ellipticity which breaks the exact axisymmetry and there may also be some migration of stars inwards or outwards. Both phenomena can be detected through kinematic analyses. We use the red clump stars selected spectroscopically from the APO Galactic Evolution Experiment, with known distances and radial velocities, to measure the radial component of the Galactocentric velocities within 5 kpc < R < 16 kpc, | b| \\lt 5^\\circ , and within 20° from the Sun–Galactic center line. The average Galactocentric radial velocity is VR = (1.48 ± 0.35)[R(kpc) ‑ (8.8 ± 2.7)] km s‑1 outwards in the explored range, with a higher contribution from stars below the Galactic plane. Two possible explanations can be given for this result: (i) the mean orbit of the disk stars is intrinsically elliptical with a Galactocentric radial gradient of eccentricity around 0.01 kpc‑1 or (ii) there is a net secular expansion of the disk, in which stars within R ≈ 9–11 kpc are migrating to the region R ≳ 11 kpc at the rate of ∼2 M⊙ yr‑1, and stars with R ≲ 9 kpc are falling toward the center of the Galaxy. This migration ratio would be unattainable for a long time and should decelerate, otherwise the Galaxy would fade away in around 1 Gyr. At present, both hypotheses are speculative and one would need data on the Galactocentric radial velocities for other azimuths different to the center or anticenter in order to confirm one of the scenarios.

  15. Radial Motions in Disk Stars: Ellipticity or Secular Flows?

    NASA Astrophysics Data System (ADS)

    López-Corredoira, M.; González-Fernández, C.

    2016-06-01

    Average stellar orbits of the Galactic disk may have some small intrinsic ellipticity which breaks the exact axisymmetry and there may also be some migration of stars inwards or outwards. Both phenomena can be detected through kinematic analyses. We use the red clump stars selected spectroscopically from the APO Galactic Evolution Experiment, with known distances and radial velocities, to measure the radial component of the Galactocentric velocities within 5 kpc < R < 16 kpc, | b| \\lt 5^\\circ , and within 20° from the Sun-Galactic center line. The average Galactocentric radial velocity is VR = (1.48 ± 0.35)[R(kpc) - (8.8 ± 2.7)] km s-1 outwards in the explored range, with a higher contribution from stars below the Galactic plane. Two possible explanations can be given for this result: (i) the mean orbit of the disk stars is intrinsically elliptical with a Galactocentric radial gradient of eccentricity around 0.01 kpc-1 or (ii) there is a net secular expansion of the disk, in which stars within R ≈ 9-11 kpc are migrating to the region R ≳ 11 kpc at the rate of ˜2 M⊙ yr-1, and stars with R ≲ 9 kpc are falling toward the center of the Galaxy. This migration ratio would be unattainable for a long time and should decelerate, otherwise the Galaxy would fade away in around 1 Gyr. At present, both hypotheses are speculative and one would need data on the Galactocentric radial velocities for other azimuths different to the center or anticenter in order to confirm one of the scenarios.

  16. Radial growth of an extended spoke in Saturn's B ring

    SciTech Connect

    Eplee, R.E.,JR.; Smith, B.A.

    1985-08-01

    An analysis is reported of the pattern of radial growth of an extended spoke observed in the Voyager 2 low-resolution Saturn ring movie. The feature is atypical in that it orbits Saturn at the corotational rate for 1-1/2 hours after the onset of its formation and then undergoes a 40-min acceleration to sustained Keplerian velocities. A correlation between the dynamical phases and the radial growth modes of the spoke is observed, one that seems consistent with the plasma cloud model of spoke formation and evolution proposed by Goertz and Morfill (1983), taken in the limit of high charge density. 13 references.

  17. Dynamics of a vortex pair in radial flow

    SciTech Connect

    Bannikova, E. Yu. Kontorovich, V. M. Reznik, G. M.

    2007-10-15

    The problem of vortex pair motion in two-dimensional radial flow is solved. Under certain conditions for flow parameters, the vortex pair can reverse its motion within a bounded region. The vortex-pair translational velocity decreases or increases after passing through the source/sink region, depending on whether the flow is diverging or converging, respectively. The rotational motion of a corotating vortex pair in a quiescent environment transforms into motion along a logarithmic spiral in radial flow. The problem may have applications in astrophysics and geophysics.

  18. Radial growth of an extended spoke in Saturn's B ring

    NASA Technical Reports Server (NTRS)

    Eplee, R. E., Jr.; Smith, B. A.

    1985-01-01

    An analysis is reported of the pattern of radial growth of an extended spoke observed in the Voyager 2 low-resolution Saturn ring 'movie'. The feature is atypical in that it orbits Saturn at the corotational rate for 1-1/2 hours after the onset of its formation and then undergoes a 40-min acceleration to sustained Keplerian velocities. A correlation between the dynamical phases and the radial growth modes of the spoke is observed, one that seems consistent with the plasma cloud model of spoke formation and evolution proposed by Goertz and Morfill (1983), taken in the limit of high charge density.

  19. Causes of Secondary Radial Nerve Palsy and Results of Treatment

    PubMed Central

    Reichert, Paweł; Wnukiewicz, Witold; Witkowski, Jarosław; Bocheńska, Aneta; Mizia, Sylwia; Gosk, Jerzy; Zimmer, Krzysztof

    2016-01-01

    Background The aim of this study was to analyze the causes that lead to secondary damage of the radial nerve and to discuss the results of reconstructive treatment. Material/Methods The study group consisted of 33 patients treated for radial nerve palsy after humeral fractures. Patients were diagnosed based on clinical examinations, ultrasonography, electromyography, or nerve conduction velocity. During each operation, the location and type of nerve damage were analyzed. During the reconstructive treatment, neurolysis, direct neurorrhaphy, or reconstruction with a sural nerve graft was used. The outcomes were evaluated using the Medical Research Council (MRC) scales and the quick DASH score. Results Secondary radial nerve palsy occurs after open reduction and internal fixation (ORIF) by plate, as well as by closed reduction and internal fixation (CRIF) by nail. In the case of ORIF, it most often occurs when the lateral approach is used, as in the case of CRIF with an insertion interlocking screws. The results of the surgical treatment were statistically significant and depended on the time between nerve injury and revision (reconstruction) surgery, type of damage to the radial nerve, surgery treatment, and type of fixation. Treatment results were not statistically significant, depending on the type of fracture or location of the nerve injury. Conclusions The potential risk of radial nerve neurotmesis justifies an operative intervention to treat neurological complications after a humeral fracture. Adequate surgical treatment in many of these cases allows for functional recovery of the radial nerve. PMID:26895570

  20. Radial and vertical flows induced by galactic spiral arms: likely contributors to our `wobbly Galaxy'

    NASA Astrophysics Data System (ADS)

    Faure, Carole; Siebert, Arnaud; Famaey, Benoit

    2014-05-01

    In an equilibrium axisymmetric galactic disc, the mean Galactocentric radial and vertical velocities are expected to be zero everywhere. In recent years, various large spectroscopic surveys have however shown that stars of the Milky Way disc exhibit non-zero mean velocities outside of the Galactic plane in both the Galactocentric radial and vertical velocity components. While radial velocity structures are commonly assumed to be associated with non-axisymmetric components of the potential such as spiral arms or bars, non-zero vertical velocity structures are usually attributed to excitations by external sources such as a passing satellite galaxy or a small dark matter substructure crossing the Galactic disc. Here, we use a three-dimensional test-particle simulation to show that the global stellar response to a spiral perturbation induces both a radial velocity flow and non-zero vertical motions. The resulting structure of the mean velocity field is qualitatively similar to what is observed across the Milky Way disc. We show that such a pattern also naturally emerges from an analytic toy model based on linearized Euler equations. We conclude that an external perturbation of the disc might not be a requirement to explain all of the observed structures in the vertical velocity of stars across the Galactic disc. Non-axisymmetric internal perturbations can also be the source of the observed mean velocity patterns.

  1. IN-SYNC. III. The Dynamical State of IC 348 - A Super-virial Velocity Dispersion and a Puzzling Sign of Convergence

    NASA Astrophysics Data System (ADS)

    Cottaar, Michiel; Covey, Kevin R.; Foster, Jonathan B.; Meyer, Michael R.; Tan, Jonathan C.; Nidever, David L.; Chojnowski, S. Drew; da Rio, Nicola; Flaherty, Kevin M.; Frinchaboy, Peter M.; Majewski, Steve; Skrutskie, Michael F.; Wilson, John C.; Zasowski, Gail

    2015-07-01

    disruption due to gas expulsion or a merger event, or (b) the population we identify as IC 348 results from the chance alignment of two sub-clusters converging along the line of sight. Additional measurements of tangential and radial velocities in IC 348 will be important for clarifying the dynamics of this region and informing models of the formation and evolution of star clusters. The radial velocities analyzed in this paper have been made available online.

  2. IN-SYNC. III. THE DYNAMICAL STATE OF IC 348—A SUPER-VIRIAL VELOCITY DISPERSION AND A PUZZLING SIGN OF CONVERGENCE

    SciTech Connect

    Cottaar, Michiel; Meyer, Michael R.; Covey, Kevin R.; Foster, Jonathan B.; Tan, Jonathan C.; Rio, Nicola da; Nidever, David L.; Chojnowski, S. Drew; Majewski, Steve; Skrutskie, Michael F.; Wilson, John C.; Zasowski, Gail; Flaherty, Kevin M.; Frinchaboy, Peter M.

    2015-07-01

    virial equilibrium after a recent disruption due to gas expulsion or a merger event, or (b) the population we identify as IC 348 results from the chance alignment of two sub-clusters converging along the line of sight. Additional measurements of tangential and radial velocities in IC 348 will be important for clarifying the dynamics of this region and informing models of the formation and evolution of star clusters. The radial velocities analyzed in this paper have been made available online.

  3. Quantitative velocity modulation spectroscopy

    NASA Astrophysics Data System (ADS)

    Hodges, James N.; McCall, Benjamin J.

    2016-05-01

    Velocity Modulation Spectroscopy (VMS) is arguably the most important development in the 20th century for spectroscopic study of molecular ions. For decades, interpretation of VMS lineshapes has presented challenges due to the intrinsic covariance of fit parameters including velocity modulation amplitude, linewidth, and intensity. This limitation has stifled the growth of this technique into the quantitative realm. In this work, we show that subtle changes in the lineshape can be used to help address this complexity. This allows for determination of the linewidth, intensity relative to other transitions, velocity modulation amplitude, and electric field strength in the positive column of a glow discharge. Additionally, we explain the large homogeneous component of the linewidth that has been previously described. Using this component, the ion mobility can be determined.

  4. Myocardial tissue phase mapping reveals impaired myocardial tissue velocities in obesity.

    PubMed

    Rider, Oliver J; Ajufo, Ezimamaka; Ali, Mohammed K; Petersen, Steffen E; Nethononda, Richard; Francis, Jane M; Neubauer, Stefan

    2015-02-01

    Although obesity is linked to heart failure on a population level, not all obese subjects develop cardiac failure. As a result, identifying obese subjects with subclinical changes in myocardial velocities may enable earlier detection of those susceptible to developing overt heart failure. As echocardiography is limited in obesity due to limited acoustic window, we used phase contrast magnetic resonance imaging to assess myocardial velocities in obese and normal weight subjects. Normal weight (BMI 23 ± 3; n = 40) and obese subjects (BMI 37 ± 7; n = 59) without identifiable cardiovascular risk factors underwent MRI (1.5 Tesla) to determine left ventricular myocardial velocities using phase contrast tissue phase mapping. Systolic function was not different between normal and obese subjects (LVEF 67 ± 5 vs 68 ± 4, p = 0.22). However, obesity was associated with significantly impaired peak radial and longitudinal diastolic myocardial velocity (by 13 and 19 % respectively, both p < 0.001). In addition time-to-peak longitudinal diastolic velocity was delayed in obesity (by 39 ms, p < 0.001). In addition, peak longitudinal diastolic strain was 20 % lower in obesity (p = 0.015) and time-to-peak longitudinal diastolic strain rate significantly delayed in obesity (by 92 ms, p < 0.001).Although peak radial systolic velocity was similar between obese and normal weight subjects (p = 0.14) peak longitudinal systolic velocity was 7 % lower in the obese cohort (p = 0.02). In obesity without co-morbidities, tissue phase mapping has shown subclinical changes in systolic and diastolic function. Given the link between obesity and heart failure, early detection of changes may become clinically important to prevent disease progression.

  5. ELECTROSTATIC MODE ASSOCIATED WITH PINCH VELOCITY IN RFPS

    SciTech Connect

    DELZANNO, GIAN LUCA; FINN, JOHN M.; CHACON, LUIS

    2007-02-08

    The existence of a new electrostatic instability is shown for RFP (reversed field pinch) equilibria. This mode arises due to the non-zero equilibrium radial flow (pinch flow). In RFP simulations with no-stress boundary conditions on the tangential velocity at the radial wall, this electrostatic mode is unstable and dominates the nonlinear dynamics, even in the presence of the MHD modes typically responsible for the reversal of the axial magnetic field at edge. Nonlinearly, this mode leads to two beams moving azimuthally towards each other, which eventually collide. The electrostatic mode can be controlled by using Dirichlet (no-slip) boundary conditions on the azimuthal velocity at the radial wall.

  6. Radial spline assembly for antifriction bearings

    NASA Technical Reports Server (NTRS)

    Moore, Jerry H. (Inventor)

    1993-01-01

    An outer race carrier is constructed for receiving an outer race of an antifriction bearing assembly. The carrier in turn is slidably fitted in an opening of a support wall to accommodate slight axial movements of a shaft. A plurality of longitudinal splines on the carrier are disposed to be fitted into matching slots in the opening. A deadband gap is provided between sides of the splines and slots, with a radial gap at ends of the splines and slots and a gap between the splines and slots sized larger than the deadband gap. With this construction, operational distortions (slope) of the support wall are accommodated by the larger radial gaps while the deadband gaps maintain a relatively high springrate of the housing. Additionally, side loads applied to the shaft are distributed between sides of the splines and slots, distributing such loads over a larger surface area than a race carrier of the prior art.

  7. The impact velocity and bone fracture pattern: Forensic perspective.

    PubMed

    Cohen, Haim; Kugel, Chen; May, Hila; Medlej, Bahaa; Stein, Dan; Slon, Viviane; Hershkovitz, Israel; Brosh, Tamar

    2016-09-01

    Studies on bone-energy interaction are meager and revealed only a general correlation between the fracture pattern and the mechanism of the insult. This study has two objectives, to establish a usable fracture analysis method and to reveal the association between the energy of the force and the fracture pattern. Dynatup Model POE 2000 (Instron Co.) low energy pendulum impact machine was utilized to apply impact loading on fresh pig femoral bones (n=30). The bone clamp shaft was adjusted to position the bone for three-point bending with additional bone compression. Three different velocities of the forced applied were carried out. On average, the number, length and the curviness of the fracture lines created under moderate and high-energy impact is significantly higher compared to a low-energy impact. Most fractures lines were located on the impacted aspect in bones subjected to moderate- and high-velocity impact. Four oblique-radial fracture lines running from the point of impact creating a double butterfly pattern were found in bones subjected to moderate and high-velocity impact. Only "false" wedge-shaped (butterfly) fragments were found in the current study. Our results suggest an association between fracture pattern and the velocity of the impact.

  8. Radial evolution of ion distribution functions

    NASA Technical Reports Server (NTRS)

    Marsch, E.

    1983-01-01

    A survey of solar wind ion velocity distributions and derived parameters (temperature, ion differential speed, heat flux, adiabatic invariants) is presented with emphasis on the heliocentric distance range between 0.3 and 1 AU traversed by the Helios solar probe. The radial evolution of nonthermal features are discussed which are observed to be most pronounced at perihelion. Within the framework of quasilinear plasma theory, wave particle interactions that may shape the ion distributions are considered. Some results of a self consistent model calculation are presented accounting for ion acceleration and heating by resonant momentum and energy exchange with ion cyclotron and magnetosonic waves propagating away from the Sun along the interplanetary magnetic field. Another tentative explanation for the occurrence of large perpendicular proton temperatures is offered in terms of heating by Landau damping of lower hybrid waves.

  9. Design and experimental evaluation of compact radial-inflow turbines

    NASA Technical Reports Server (NTRS)

    Fredmonski, A. J.; Huber, F. W.; Roelke, R. J.; Simonyi, S.

    1991-01-01

    The application of a multistage 3D Euler solver to the aerodynamic design of two compact radial-inflow turbines is presented, along with experimental results evaluating and validating the designs. The objectives of the program were to design, fabricate, and rig test compact radial-inflow turbines with equal or better efficiency relative to conventional designs, while having 40 percent less rotor length than current traditionally-sized radial turbines. The approach to achieving these objectives was to apply a calibrated 3D multistage Euler code to accurately predict and control the high rotor flow passage velocities and high aerodynamic loadings resulting from the reduction in rotor length. A comparison of the advanced compact designs to current state-of-the-art configurations is presented.

  10. Linear stability of radially-heated circular Couette flow with simulated radial gravity

    NASA Astrophysics Data System (ADS)

    Tagg, Randy; Weidman, Patrick D.

    2007-05-01

    The stability of circular Couette flow between vertical concentric cylinders in the presence of a radial temperature gradient is considered with an effective “radial gravity.” In addition to terrestrial buoyancy - ρg e z we include the term - ρg m f(r)e r where g m f(r) is the effective gravitational acceleration directed radially inward across the gap. Physically, this body force arises in experiments using ferrofluid in the annular gap of a Taylor Couette cell whose inner cylinder surrounds a vertical stack of equally spaced disk magnets. The radial dependence f(r) of this force is proportional to the modified Bessel function K 1(κr), where 2π/κ is the spatial period of the magnetic stack and r is the radial coordinate. Linear stability calculations made to compare with conditions reported by Ali and Weidman (J. Fluid Mech., 220, 1990) show strong destabilization effects, measured by the onset Rayleigh number R, when the inner wall is warmer, and strong stabilization effects when the outer wall is warmer, with increasing values of the dimensionless radial gravity γ = g m /g. Further calculations presented for the geometry and fluid properties of a terrestrial laboratory experiment reveal a hitherto unappreciated structure of the stability problem for differentially-heated cylinders: multiple wavenumber minima exist in the marginal stability curves. Transitions in global minima among these curves give rise to a competition between differing instabilities of the same spiral mode number, but widely separated axial wavenumbers.

  11. Solar-wind velocity decreases

    NASA Astrophysics Data System (ADS)

    Geranios, A.

    1980-08-01

    A model is developed to account for the solar wind electron and proton temperature decreases observed following the passage of an interplanetary shock wave and during the velocity decrease of a solar wind stream. The equations of mass and energy conservation are solved for a fully ionized, electrically neutral plasma expanding radially and spherically symmetrically, taking into account the heat flux from the solor corona to the plasma along the open magnetic field lines, and the electron thermal conductivity. An analytical relationship between the temperature and the velocity of the solar wind plasma is obtained which is found to be in agreement with experimental measurements made by the Vela 5 and 6 and IMP 6 satellites from August 1969-May 1974. It is thus proposed that the observed low plasma temperatures are due to the fact that the temperature decrease of the expanding plasma exceeds the heat gain due to thermal conduction from the corona.

  12. Propagation of transverse waves in a radially expanding plasma

    NASA Technical Reports Server (NTRS)

    Solodyna, C. V.; Belcher, J. W.

    1974-01-01

    Investigation of the properties of low-frequency transverse waves in an expanding plasma. The wave vector, the background magnetic field, and the streaming velocity of the plasma are all assumed to lie along the radial direction. Expressions are presented for the radial dependence of the amplitude and phase of left and right circularly polarized waves, correct to first order in the wave frequency divided by the proton cyclotron frequency. Differences in the phase velocities of these two circular polarizations result in a Faraday rotation that can be substantial for typical interplanetary conditions near 1 AU. The implications of these results for a realistic solar wind model with the interplanetary magnetic field along the spiral direction are also considered.

  13. Gaussian Velocity Distributions in Avalanches

    NASA Astrophysics Data System (ADS)

    Shattuck, Mark

    2004-03-01

    Imagine a world where gravity is so strong that if an ice cube is tilted the shear forces melt the surface and water avalanches down. Further imagine that the ambient temperature is so low that the water re-freezes almost immediately. This is the world of granular flows. As a granular solid is tilted the surface undergoes a sublimation phase transition and a granular gas avalanches down the surface, but the inelastic collisions rapidly remove energy from the flow lowering the granular temperature (kinetic energy per particle) until the gas solidifies again. It is under these extreme conditions that we attempt to uncover continuum granular flow properties. Typical continuum theories like Navier-Stokes equation for fluids follow the space-time evolution of the first few moments of the velocity distribution. We study continuously avalanching flow in a rotating two-dimensional granular drum using high-speed video imaging and extract the position and velocities of the particles. We find a universal near Gaussian velocity distribution throughout the flowing regions, which are characterized by a liquid-like radial distribution function. In the remaining regions, in which the radial distribution function develops sharp crystalline peaks, the velocity distribution has a Gaussian peak but is much broader in the tails. In a companion experiment on a vibrated two-dimensional granular fluid under constant pressure, we find a clear gas-solid phase transition in which both the temperature and density change discontinuously. This suggests that a low temperature crystal and a high temperature gas can coexist in steady state. This coexistence could result in a narrower, cooler, Gaussian peak and a broader, warmer, Gaussian tail like the non-Gaussian behavior seen in the crystalline portions of the rotating drum.

  14. Radial lean direct injection burner

    DOEpatents

    Khan, Abdul Rafey; Kraemer, Gilbert Otto; Stevenson, Christian Xavier

    2012-09-04

    A burner for use in a gas turbine engine includes a burner tube having an inlet end and an outlet end; a plurality of air passages extending axially in the burner tube configured to convey air flows from the inlet end to the outlet end; a plurality of fuel passages extending axially along the burner tube and spaced around the plurality of air passage configured to convey fuel from the inlet end to the outlet end; and a radial air swirler provided at the outlet end configured to direct the air flows radially toward the outlet end and impart swirl to the air flows. The radial air swirler includes a plurality of vanes to direct and swirl the air flows and an end plate. The end plate includes a plurality of fuel injection holes to inject the fuel radially into the swirling air flows. A method of mixing air and fuel in a burner of a gas turbine is also provided. The burner includes a burner tube including an inlet end, an outlet end, a plurality of axial air passages, and a plurality of axial fuel passages. The method includes introducing an air flow into the air passages at the inlet end; introducing a fuel into fuel passages; swirling the air flow at the outlet end; and radially injecting the fuel into the swirling air flow.

  15. Radial Electromagnetic Press for Ignitor

    NASA Astrophysics Data System (ADS)

    Pizzuto, A.; Capriccioli, A.; Gasparotto, M.; Palmieri, A.; Rita, C.; Roccella, M.; Coppi, B.

    1996-11-01

    The active vertical press included so far in the Ignitor design can be substituted advantageously (e.g. in terms of the machine maintenance procedure) by a radial electromagnetic press, without involving modification of the main machine components. Only the bracing ring of the radial mechanical preloading system that is permanently applied requires some changes. The radial press has to compensate for the reduced ring load (from 200 MN to 120 MN) and the original vertical press load of 35 MN. To get an equivalent preloading system, the radial press load has to be 140 MN, which is 25 MN higher, to account for the lower efficiency of the radial load. The current needed to originate the 140 MN force is about 3.2 MA. The press is active for 2 s starting from the plasma current rise. The temperature increase is about 20 ^oC. The stray field at the plasma border is well within the allowable value and can be easily compensated by varying slightly the current of one couple of poloidal coils. The new machine layout is illustrated and the electromagnetic and mechanical analyses carried out for the new configuration are given. Sponsored by ENEA, CNR and ASP, of Italy, and by the US DoE

  16. Reactive-infiltration instability in radial geometry

    NASA Astrophysics Data System (ADS)

    Grodzki, Piotr; Szymczak, Piotr

    2015-04-01

    A planar dissolution front propagating through a homogeneous porous matrix is unstable with respect to small variations in local permeability; regions of high permeability dissolve faster because of enhanced transport of reactants, which leads to increased rippling of the front. This phenomenon, usually referred to known as reactive-infiltration instability is an important mechanism for pattern development in geology, with a range of morphologies and scales, from cave systems running for hundreds of miles to laboratory acidization on the scale of centimeters. In general, this instability is characterized by two length scales: the diffusive length (D/v) and the reactant penetration length (v/r), where v is the Darcy velocity, D - the diffusion constant and r - the dissolution rate. If the latter scale is much smaller than the former one can adopt the so-called thin front limit, where the interface is treated as a discontinuity in porosity, with a completely dissolved phase on one side and an undissolved phase on the other. Linear stability analysis for this case has been carried out by Chadam et al. [1], and the corresponding dispersion relation shows that long wavelengths are unstable, whereas short wavelengths are stabilized by diffusion. In their derivation, Chadam et al. have considered a linear geometry with a uniform pressure gradient applied along one of the directions. However, in many cases (e.g. in the acidization techniques used in oil industry) the reactive fluids are injected through a well and thus the relevant geometry is radial rather than linear. Motivated by this, we have carried out the linear stability analysis of the reactive-infiltration problem in radial geometry, with the fluid injection at the centre of the system. We stay within the thin-front limit and derive the corresponding dispersion relation, which shows the stable regions for both the long-wavelength and short-wavelength modes, and the unstable region in between. Next, we study how

  17. Fractures of the Radial Head.

    PubMed

    Burkhart, Klaus Josef; Wegmann, Kilian; Müller, Lars P; Gohlke, Frank E

    2015-11-01

    Radial head fractures are the most common fractures around the elbow. Because they are often accompanied by ligamentous injuries, we recommend considering them to be osteoligamentous injuries rather than simple fractures, even in undisplaced or minimally displaced fractures. Surgeons should always suspect and actively exclude concomitant ligament tears. The incidence of these associated injuries increases with greater severity of the radial head fracture. However, the standard Mason classification system does not adequately address this problem, and all attempts to establish a new classification system that provides concise treatment algorithms have failed. This article discusses the current treatment options and the current controversies in nonsurgical therapy, open reduction and internal fixation (ORIF) and radial head replacement. PMID:26498543

  18. P wave azimuthal and radial anisotropy of the Hokkaido subduction zone

    NASA Astrophysics Data System (ADS)

    Niu, Xiongwei; Zhao, Dapeng; Li, Jiabiao; Ruan, Aiguo

    2016-04-01

    We present the first three-dimensional P wave radial anisotropy tomography of the Hokkaido subduction zone, as well as P wave azimuthal anisotropy and S wave tomography, which are determined by inverting 298,430 P wave and 233,934 S wave arrival times from 14,245 local earthquakes recorded by 344 seismic stations. Our results reveal significant velocity heterogeneity, seismic anisotropy, and upwelling flows beneath the study region. In the mantle wedge, prominent low-velocity (low-V) anomalies exhibit trench-normal fast-velocity directions (FVDs) and a negative radial anisotropy (i.e., vertical velocity > horizontal velocity), which may reflect upwelling mantle flows. Fan-shaped FVDs are found at depths of 65-90 km, and a detailed 3-D mantle flow pattern is revealed, which may be caused by a combination of oblique subduction of the Pacific plate and collision of the Kuril arc with the Honshu arc beneath southern Hokkaido. The radial anisotropy changes at ~100 km depth, which may reflect variations in temperature and fluid conditions there. The subducting Pacific slab exhibits a positive radial anisotropy (i.e., horizontal velocity > vertical velocity), which may reflect the original fossil anisotropy when the Pacific plate formed at the mid-ocean ridge.

  19. Parachute drag and radial force

    SciTech Connect

    Purvis, J.W.

    1986-01-01

    This paper presents a combination of old and new wind tunnel data in a format which illustrates the effects of inflated diameter, geometric porosity, reefing line length, suspension line length, number of gores, and number of ribbons on parachute drag. A new definition of radial force coefficient is presented, as well as a universal drag curve for flat circular and conical parachutes.

  20. Outcomes Following Radial Head Arthroplasty.

    PubMed

    Fowler, John R; Henry, Sarah E; Xu, Peter; Goitz, Robert J

    2016-05-01

    Most current series of radial head arthroplasty include small numbers of patients with short- to medium-term follow-up and significant heterogeneity in patients, treatments, and outcome measures. The purpose of this systematic review was to review outcomes for radial head arthroplasty based on injury chronicity, injury pattern, and type of implant used. The authors systematically searched electronic databases for studies containing radial head arthroplasty or radial head replacement and identified 19 studies for inclusion in the analysis. For each included study, a composite mean was obtained for Mayo Elbow Performance Score (MEPS) and range of motion. Outcomes were said to differ significantly if their confidence intervals did not overlap. The MEPS for acute treatment (90) was higher than that for delayed treatment (81). There was no difference in the pooled MEPS between the isolated (89) and complex injury pattern (87) groups or implant material. There was no difference in range of motion between the acute and delayed or isolated and complex groups, but the average degree of pronation was higher in patients treated with titanium implants (76°) compared with cobalt chromium implants (66°). This systematic review suggests that outcomes are improved following acute arthroplasty for treatment of radial head fractures compared with delayed treatment, based on MEPS. The lack of other significant differences detected is likely due to the significant heterogeneity and inadequate power in current studies. Further prospective studies isolating the different variables will be needed to determine their true effect on outcomes. [Orthopedics. 2016; 39(3):153-160.]. PMID:27045484

  1. 9 Aurigae: strong evidence for non-radial pulsations

    NASA Astrophysics Data System (ADS)

    Krisciunas, K.; Griffin, R. F.; Guinan, E. F.; Luedeke, K. D.; McCook, G. P.

    1995-04-01

    We present further photometric observations of the unusual F0 V star 9 Aurigae and present evidence that this star's radial velocity, spectroscopic line widths and line depths are also variable with the same frequencies as the photometric data (f_1~=0.795 and f_2~=0.345 d^-1). The phases of these sinusoids are stable over time-scales of longer than one year, though the amplitudes can vary, making the prediction of photometric behaviour impossible. Given that a variety of other explanations have already been discounted (e.g. interactions with a close companion, the existence of a lumpy, orbiting ring of dust, or star spots) and that these variations occur on time-scales an order of magnitude slower than the fundamental radial pulsation period, we have very strong evidence that 9 Aurigae exhibits non-radial g-mode pulsations. Since the power spectrum of the radial velocity data shows frequency f_2 but does not clearly show f_1, the present data suggest that f_2 is associated with a low-degree spherical harmonic L=1 or 2), while f_1 is associated with a higher degree harmonic. 9 Aurigae, along with such stars as gamma Doradus, HD 224638, HD 224945, and HD 164615, appears to constitute a new class of pulsating variables. These stars are to be found at or beyond the cool edge of the Cepheid instability strip in the HR Diagram. Prior to this, only much hotter stars have been shown to exhibit non-radial g-modes.

  2. The Polarity Protein Pals1 Regulates Radial Sorting of Axons.

    PubMed

    Zollinger, Daniel R; Chang, Kae-Jiun; Baalman, Kelli; Kim, Seonhee; Rasband, Matthew N

    2015-07-22

    Myelin is essential for rapid and efficient action potential propagation in vertebrates. However, the molecular mechanisms regulating myelination remain incompletely characterized. For example, even before myelination begins in the PNS, Schwann cells must radially sort axons to form 1:1 associations. Schwann cells then ensheathe and wrap axons, and establish polarized, subcellular domains, including apical and basolateral domains, paranodes, and Schmidt-Lanterman incisures. Intriguingly, polarity proteins, such as Pals1/Mpp5, are highly enriched in some of these domains, suggesting that they may regulate the polarity of Schwann cells and myelination. To test this, we generated mice with Schwann cells and oligodendrocytes that lack Pals1. During early development of the PNS, Pals1-deficient mice had impaired radial sorting of axons, delayed myelination, and reduced nerve conduction velocities. Although myelination and conduction velocities eventually recovered, polyaxonal myelination remained a prominent feature of adult Pals1-deficient nerves. Despite the enrichment of Pals1 at paranodes and incisures of control mice, nodes of Ranvier and paranodes were unaffected in Pals1-deficient mice, although we measured a significant increase in the number of incisures. As in other polarized cells, we found that Pals1 interacts with Par3 and loss of Pals1 reduced levels of Par3 in Schwann cells. In the CNS, loss of Pals1 affected neither myelination nor the establishment of polarized membrane domains. These results demonstrate that Schwann cells and oligodendrocytes use distinct mechanisms to control their polarity, and that radial sorting in the PNS is a key polarization event that requires Pals1. Significance statement: This paper reveals the role of the canonical polarity protein Pals1 in radial sorting of axons by Schwann cells. Radial sorting is essential for efficient and proper myelination and is disrupted in some types of congenital muscular dystrophy.

  3. Near-Field Characterization of Radial and Axial Blast Waves From a Cylindrical Explosive Charge

    NASA Astrophysics Data System (ADS)

    McNesby, Kevin; Homan, Barrie

    This paper uses experiment (high speed imaging) and simulation (ALE-3D) to investigate radial and axial blast waves produced by uncased, cylindrical charges of TNT (trinitrotoluene). Recently there has been work reported on predicting secondary blast waves in the explosive mid-field (approximately 1 meter from charge center of mass) for cylindrical charges of RDX (trimethylenetrinitramine)/binder formulations. The work we will present seeks to provide complementary information in the explosive near-field, including the approach to chemical ``freeze out'', for end-detonated, right circular cylinders of TNT. Additionally, this work attempts to retrieve state variables (temperature, pressure, velocities) from high-definition images of the explosive event. Keywords: cylindrical charges, blast, shock waves

  4. Measurements of Coronal Proton Velocity Distributions

    NASA Astrophysics Data System (ADS)

    Kohl, J. L.; Panasyuk, A.; Cranmer, S. R.; Gardner, L. D.; Raymond, J. C.

    2007-12-01

    The Ultraviolet Coronagraph Spectrometer (UVCS) on the Solar and Heliospheric Observatory is being used to measure precise coronal H I Ly-alpha spectral line profiles out to several Doppler half widths. Such observations can be used to reveal the proton velocity distribution along the line-of-sight. Departures from a Maxwellian distribution are believed to be needed for the acceleration of solar energetic particles (SEPs) by coronal mass ejection (CME) shocks. Our initial attempt to measure suprathermal proton velocity distributions has been described by Kohl et al. (2006). We have made considerable additional progress on such measurements since then. Improvements include the following: a much more accurate instrument spectral line profile, an increase in the wavelength range used for the observations, an increase in the statistical accuracy of the observations by increasing the observation time, and inclusion of a background measurement as part of every set of observations. We have also investigated the sensitivity to the detector high voltage, investigated the effects of diffraction in the instrument, determined the stray light effects and the Thompson scattering effects, which both turn out to be small except for scattering of Si III 120.6 nm. That scattered light is out of the primary wavelength range of interest. We believe that we have now demonstrated that UVCS has the sensitivity to distinguish between a Gaussian coronal velocity distribution and a kappa = 4 or smaller distribution. It is generally believed that the required seed particle population needed to produce SEPs of interest with a CME shock would have a velocity distribution with 0.001 to 0.01 of the particles with speeds that exceed 1000 km/s. Assuming a kappa distribution that is symmetric in the tangential plane and Maxwellian in the radial direction, this would correspond to a distribution with kappa = 3.5 or smaller. This paper will report the results of examining a fairly large body of new

  5. Velocity anisotropy in tidally limited star clusters

    NASA Astrophysics Data System (ADS)

    Tiongco, Maria A.; Vesperini, Enrico; Varri, Anna Lisa

    2016-02-01

    We explore the long-term evolution of the anisotropy in the velocity space of star clusters starting with different structural and kinematical properties. We show that the evolution of the radial anisotropy strength and its radial variation within a cluster contain distinct imprints of the cluster initial structural properties, dynamical history, and of the external tidal field of its host galaxy. Initially isotropic and compact clusters with small initial values of the ratio of the half-mass to Jacobi radius, rh/rJ, develop a strong radial anisotropy during their long-term dynamical evolution. Many clusters, if formed with small values of rh/rJ, should now be characterized by a significant radial anisotropy increasing with the distance from the cluster centre, reaching its maximum at a distance between 0.2 rJ and 0.4 rJ, and then becoming more isotropic or mildly tangentially anisotropic in the outermost regions. A similar radial variation of the anisotropy can also result from an early violent relaxation phase. In both cases, as a cluster continues its evolution and loses mass, the anisotropy eventually starts to decrease and the system evolves towards an isotropic velocity distribution. However, in order to completely erase the strong anisotropy developed by these compact systems during their evolution, they must be in the advanced stages of their evolution and lose a large fraction of their initial mass. Clusters that are initially isotropic and characterized by larger initial values of rh/rJ, on the other hand, never develop a significant radial anisotropy.

  6. Application of Vectors to Relative Velocity

    ERIC Educational Resources Information Center

    Tin-Lam, Toh

    2004-01-01

    The topic 'relative velocity' has recently been introduced into the Cambridge Ordinary Level Additional Mathematics syllabus under the application of Vectors. In this note, the results of relative velocity and the 'reduction to rest' technique of teaching relative velocity are derived mathematically from vector algebra, in the hope of providing…

  7. Horns as particle velocity amplifiers.

    PubMed

    Donskoy, Dimitri M; Cray, Benjamin A

    2011-11-01

    Preliminary measurements and numerical predictions reveal that simple, and relatively small, horns generate remarkable amplification of acoustic particle velocity. For example, below 2 kHz, a 2.5 cm conical horn has a uniform velocity amplification ratio (throat-to-mouth) factor of approximately 3, or, in terms of a decibel level, 9.5 dB. It is shown that the velocity amplification factor depends on the horn's mouth-to-throat ratio as well as, though to a lesser degree, the horn's flare rate. A double horn configuration provides limited additional gain, approximately an increase of up to 25%.

  8. Improved sliced velocity map imaging apparatus optimized for H photofragments

    SciTech Connect

    Ryazanov, Mikhail; Reisler, Hanna

    2013-04-14

    Time-sliced velocity map imaging (SVMI), a high-resolution method for measuring kinetic energy distributions of products in scattering and photodissociation reactions, is challenging to implement for atomic hydrogen products. We describe an ion optics design aimed at achieving SVMI of H fragments in a broad range of kinetic energies (KE), from a fraction of an electronvolt to a few electronvolts. In order to enable consistently thin slicing for any imaged KE range, an additional electrostatic lens is introduced in the drift region for radial magnification control without affecting temporal stretching of the ion cloud. Time slices of {approx}5 ns out of a cloud stretched to Greater-Than-Or-Slanted-Equal-To 50 ns are used. An accelerator region with variable dimensions (using multiple electrodes) is employed for better optimization of radial and temporal space focusing characteristics at each magnification level. The implemented system was successfully tested by recording images of H fragments from the photodissociation of HBr, H{sub 2}S, and the CH{sub 2}OH radical, with kinetic energies ranging from <0.4 eV to >3 eV. It demonstrated KE resolution Less-Than-Or-Equivalent-To 1%-2%, similar to that obtained in traditional velocity map imaging followed by reconstruction, and to KE resolution achieved previously in SVMI of heavier products. We expect it to perform just as well up to at least 6 eV of kinetic energy. The tests showed that numerical simulations of the electric fields and ion trajectories in the system, used for optimization of the design and operating parameters, provide an accurate and reliable description of all aspects of system performance. This offers the advantage of selecting the best operating conditions in each measurement without the need for additional calibration experiments.

  9. Improved sliced velocity map imaging apparatus optimized for H photofragments.

    PubMed

    Ryazanov, Mikhail; Reisler, Hanna

    2013-04-14

    Time-sliced velocity map imaging (SVMI), a high-resolution method for measuring kinetic energy distributions of products in scattering and photodissociation reactions, is challenging to implement for atomic hydrogen products. We describe an ion optics design aimed at achieving SVMI of H fragments in a broad range of kinetic energies (KE), from a fraction of an electronvolt to a few electronvolts. In order to enable consistently thin slicing for any imaged KE range, an additional electrostatic lens is introduced in the drift region for radial magnification control without affecting temporal stretching of the ion cloud. Time slices of ∼5 ns out of a cloud stretched to ⩾50 ns are used. An accelerator region with variable dimensions (using multiple electrodes) is employed for better optimization of radial and temporal space focusing characteristics at each magnification level. The implemented system was successfully tested by recording images of H fragments from the photodissociation of HBr, H2S, and the CH2OH radical, with kinetic energies ranging from <0.4 eV to >3 eV. It demonstrated KE resolution ≲1%-2%, similar to that obtained in traditional velocity map imaging followed by reconstruction, and to KE resolution achieved previously in SVMI of heavier products. We expect it to perform just as well up to at least 6 eV of kinetic energy. The tests showed that numerical simulations of the electric fields and ion trajectories in the system, used for optimization of the design and operating parameters, provide an accurate and reliable description of all aspects of system performance. This offers the advantage of selecting the best operating conditions in each measurement without the need for additional calibration experiments.

  10. Radial coordinates for conformal blocks

    NASA Astrophysics Data System (ADS)

    Hogervorst, Matthijs; Rychkov, Slava

    2013-05-01

    We develop the theory of conformal blocks in CFTd expressing them as power series with Gegenbauer polynomial coefficients. Such series have a clear physical meaning when the conformal block is analyzed in radial quantization: individual terms describe contributions of descendants of a given spin. Convergence of these series can be optimized by a judicious choice of the radial quantization origin. We argue that the best choice is to insert the operators symmetrically. We analyze in detail the resulting “ρ-series” and show that it converges much more rapidly than for the commonly used variable z. We discuss how these conformal block representations can be used in the conformal bootstrap. In particular, we use them to derive analytically some bootstrap bounds whose existence was previously found numerically.

  11. RADIAL STABILITY IN STRATIFIED STARS

    SciTech Connect

    Pereira, Jonas P.; Rueda, Jorge A. E-mail: jorge.rueda@icra.it

    2015-03-01

    We formulate within a generalized distributional approach the treatment of the stability against radial perturbations for both neutral and charged stratified stars in Newtonian and Einstein's gravity. We obtain from this approach the boundary conditions connecting any two phases within a star and underline its relevance for realistic models of compact stars with phase transitions, owing to the modification of the star's set of eigenmodes with respect to the continuous case.

  12. Measurement of Poloidal Velocity on the National Spherical Torus Experiment

    SciTech Connect

    Ronald E. Bell and Russell Feder

    2010-06-04

    A diagnostic suite has been developed to measure impurity poloidal flow using charge exchange recombination spectroscopy on the National Spherical Torus Experiment. Toroidal and poloidal viewing systems measure all quantities required to determine the radial electric field. Two sets of up/down symmetric poloidal views are used to measure both active emission in the plane of the neutral heating beams and background emission in a radial plane away from the neutral beams. Differential velocity measurements isolate the line-integrated poloidal velocity from apparent flows due to the energy-dependent chargeexchange cross section. Six f/1.8 spectrometers measure 276 spectra to obtain 75 active and 63 background channels every 10 ms. Local measurements from a similar midplane toroidal viewing system are mapped into two dimensions to allow the inversion of poloidal line-integrated measurements to obtain local poloidal velocity profiles. Radial resolution after inversion is 0.6-1.8 cm from the plasma edge to the center.

  13. Velocidades radiales en Collinder 121

    NASA Astrophysics Data System (ADS)

    Arnal, M.; Morrell, N.

    Se han llevado a cabo observaciones espectroscópicas de unas treinta estrellas que son posibles miembros del cúmulo abierto Collinder 121. Las mismas fueron realizadas con el telescopio de 2.15m del Complejo Astronómico El Leoncito (CASLEO). El análisis de las velocidades radiales derivadas del material obtenido, confirma la realidad de Collinder 121, al menos desde el punto de vista cinemático. La velocidad radial baricentral (LSR) del cúmulo es de +17 ± 3 km.s-1. Esta velocidad coincide, dentro de los errores, con la velocidad radial (LSR) de la nebulosa anillo S308, la cual es de ~20 ± 10 km.s-1. Como S308 se encuentra físicamente asociada a la estrella Wolf-Rayet HD~50896, es muy probable que esta última sea un miembro de Collinder 121. Desde un punto de vista cinemático, la supergigante roja HD~50877 (K3Iab) también pertenecería a Collinder 121. Basándonos en la pertenencia de HD~50896 a Collinder 121, y en la interacción encontrada entre el viento de esta estrella y el medio interestelar circundante a la misma, se estima para este cúmulo una distancia del orden de 1 kpc.

  14. Effect of radial inflow on vortex intensification for a tornado-type wind turbine

    SciTech Connect

    Hsu, C.T.; Ide, H.

    1982-09-01

    A new wind vortex turbine, called tornado-type wind turbine, was studied both theoretically and experimentally for the purpose of better understanding the basic nature of a vortex flow and further improvement of its power efficiencies. Analytical solutions were obtained from the Navier-Stokes equations for the velocity distributions along the radial distance. The result demonstrates the important nature of a vortex structure that, in order to intensify a vortex inside the tower, radial inflow must be provided from the side walls. Based upon this concept, the essential contribution of our experimental work was to furnish the radial inflow by utilizing the dynamic head of incoming wind.

  15. Radial and poloidal correlation reflectometry on Experimental Advanced Superconducting Tokamak

    SciTech Connect

    Qu, Hao; Zhang, Tao; Han, Xiang; Wen, Fei; Zhang, Shoubiao; Kong, Defeng; Wang, Yumin; Gao, Yu; Huang, Canbin; Cai, Jianqing; Gao, Xiang

    2015-08-15

    An X-mode polarized V band (50 GHz–75 GHz) radial and poloidal correlation reflectometry is designed and installed on Experimental Advanced Superconducting Tokamak (EAST). Two frequency synthesizers (12 GHz–19 GHz) are used as sources. Signals from the sources are up-converted to V band using active quadruplers and then coupled together for launching through one single pyramidal antenna. Two poloidally separated antennae are installed to receive the reflected waves from plasma. This reflectometry system can be used for radial and poloidal correlation measurement of the electron density fluctuation. In ohmically heated plasma, the radial correlation length is about 1.5 cm measured by the system. The poloidal correlation analysis provides a means to estimate the fluctuation velocity perpendicular to the main magnetic field. In the present paper, the distance between two poloidal probing points is calculated with ray-tracing code and the propagation time is deduced from cross-phase spectrum. Fluctuation velocity perpendicular to the main magnetic field in the core of ohmically heated plasma is about from −1 km/s to −3 km/s.

  16. Radial and poloidal correlation reflectometry on Experimental Advanced Superconducting Tokamak

    NASA Astrophysics Data System (ADS)

    Qu, Hao; Zhang, Tao; Han, Xiang; Wen, Fei; Zhang, Shoubiao; Kong, Defeng; Wang, Yumin; Gao, Yu; Huang, Canbin; Cai, Jianqing; Gao, Xiang

    2015-08-01

    An X-mode polarized V band (50 GHz-75 GHz) radial and poloidal correlation reflectometry is designed and installed on Experimental Advanced Superconducting Tokamak (EAST). Two frequency synthesizers (12 GHz-19 GHz) are used as sources. Signals from the sources are up-converted to V band using active quadruplers and then coupled together for launching through one single pyramidal antenna. Two poloidally separated antennae are installed to receive the reflected waves from plasma. This reflectometry system can be used for radial and poloidal correlation measurement of the electron density fluctuation. In ohmically heated plasma, the radial correlation length is about 1.5 cm measured by the system. The poloidal correlation analysis provides a means to estimate the fluctuation velocity perpendicular to the main magnetic field. In the present paper, the distance between two poloidal probing points is calculated with ray-tracing code and the propagation time is deduced from cross-phase spectrum. Fluctuation velocity perpendicular to the main magnetic field in the core of ohmically heated plasma is about from -1 km/s to -3 km/s.

  17. Radial and poloidal correlation reflectometry on Experimental Advanced Superconducting Tokamak.

    PubMed

    Qu, Hao; Zhang, Tao; Han, Xiang; Wen, Fei; Zhang, Shoubiao; Kong, Defeng; Wang, Yumin; Gao, Yu; Huang, Canbin; Cai, Jianqing; Gao, Xiang

    2015-08-01

    An X-mode polarized V band (50 GHz-75 GHz) radial and poloidal correlation reflectometry is designed and installed on Experimental Advanced Superconducting Tokamak (EAST). Two frequency synthesizers (12 GHz-19 GHz) are used as sources. Signals from the sources are up-converted to V band using active quadruplers and then coupled together for launching through one single pyramidal antenna. Two poloidally separated antennae are installed to receive the reflected waves from plasma. This reflectometry system can be used for radial and poloidal correlation measurement of the electron density fluctuation. In ohmically heated plasma, the radial correlation length is about 1.5 cm measured by the system. The poloidal correlation analysis provides a means to estimate the fluctuation velocity perpendicular to the main magnetic field. In the present paper, the distance between two poloidal probing points is calculated with ray-tracing code and the propagation time is deduced from cross-phase spectrum. Fluctuation velocity perpendicular to the main magnetic field in the core of ohmically heated plasma is about from -1 km/s to -3 km/s.

  18. Onset of radial flow in p+p collisions

    SciTech Connect

    Jiang, Kun; Zhu, Yinying; Liu, Weitao; Chen, Hongfang; Li, Cheng; Ruan, Lijuan; Tang, Zebo; Xu, Zhangbu

    2015-02-23

    It has been debated for decades whether hadrons emerging from p+p collisions exhibit collective expansion. The signal of the collective motion in p+p collisions is not as clear as in heavy-ion collisions because of the low multiplicity and large fluctuation in p+p collisions. Tsallis Blast-Wave (TBW) model is a thermodynamic approach, introduced to handle the overwhelming correlation and fluctuation in the hadronic processes. We have systematically studied the identified particle spectra in p+p collisions from RHIC to LHC using TBW and found no appreciable radial flow in p+p collisions below √s = 900 GeV. At LHC higher energy of 7 TeV in p+p collisions, the radial flow velocity achieves an average of (β) = 0.320 ± 0.005. This flow velocity is comparable to that in peripheral (40-60%) Au+Au collisions at RHIC. In addition, breaking of the identified particle spectra mT scaling was also observed at LHC from a model independent test.

  19. Blowoff characteristics of bluff-body stabilized conical premixed flames with upstream spatial mixture gradients and velocity oscillations

    SciTech Connect

    Chaudhuri, Swetaprovo; Cetegen, Baki M.

    2008-06-15

    This experimental study concerns determination of blowoff equivalence ratios for lean premixed conical flames for different mixture approach velocities ranging from 5 to 16 m/s in the presence of spatial mixture gradients and upstream velocity modulation. Conical flames were anchored on a disk-shaped bluff body that was attached to a central rod in the burner nozzle. A combustible propane-air mixture flowed through a converging axisymmetric nozzle with a concentric insert, allowing radial mixture variation by tailoring the composition in the inner and outer parts of the nozzle. The radial mixture profiles were characterized near the location of the flame holder by laser Rayleigh light scattering. Additionally, a loudspeaker at the nozzle base allowed introduction of periodic velocity oscillations with an amplitude of 9% of the mean flow velocity up to a frequency of 350 Hz. The flame blowoff equivalence ratio was experimentally determined by continuously lowering the fuel flow rates and determining the flame detachment point from the flame holder. Flame detachment was detected by a rapid reduction of CH* emission from the flame base imaged by a photomultiplier detector. It was found that the flame blowoff is preceded by progressive narrowing of the flame cone for the case of higher inner jet equivalence ratios. In this case, the fuel-lean outer flow cannot sustain combustion, and clearly this is not a good way of operating a combustor. Nevertheless, the overall blowoff equivalence ratio is reduced by inner stream fuel enrichment. A possible explanation for this behavior is given based on the radial extent of the variable-equivalence-ratio mixture burning near the flame stabilization region. Fuel enrichment in the outer flow was found to have no effect on blowoff as compared to the case of uniform mixture. The results were similar for the whole range of mean flow velocities and upstream excitation frequencies. (author)

  20. Measuring the Stellar Halo Velocity Anisotropy With 3D Kinematics

    NASA Astrophysics Data System (ADS)

    Cunningham, Emily C.; Deason, Alis J.; Guhathakurta, Puragra; Rockosi, Constance M.; van der Marel, Roeland P.; Sohn, S. Tony

    2016-08-01

    We present the first measurement of the anisotropy parameter β using 3D kinematic information outside of the solar neighborhood. Our sample consists of 13 Milky Way halo stars with measured proper motions and radial velocities in the line of sight of M31. Proper motions were measured using deep, multi-epoch HST imaging, and radial velocities were measured from Keck II/DEIMOS spectra. We measure β = -0.3-0.9 +0.4, which is consistent with isotropy, and inconsistent with measurements in the solar neighborhood. We suggest that this may be the kinematic signature of a relatively early, massive accretion event, or perhaps several such events.

  1. A radial transmission line material measurement apparatus

    SciTech Connect

    Warne, L.K.; Moyer, R.D.; Koontz, T.E.; Morris, M.E.

    1993-05-01

    A radial transmission line material measurement sample apparatus (sample holder, offset short standards, measurement software, and instrumentation) is described which has been proposed, analyzed, designed, constructed, and tested. The purpose of the apparatus is to obtain accurate surface impedance measurements of lossy, possibly anisotropic, samples at low and intermediate frequencies (vhf and low uhf). The samples typically take the form of sections of the material coatings on conducting objects. Such measurements thus provide the key input data for predictive numerical scattering codes. Prediction of the sample surface impedance from the coaxial input impedance measurement is carried out by two techniques. The first is an analytical model for the coaxial-to-radial transmission line junction. The second is an empirical determination of the bilinear transformation model of the junction by the measurement of three full standards. The standards take the form of three offset shorts (and an additional lossy Salisbury load), which have also been constructed. The accuracy achievable with the device appears to be near one percent.

  2. Gas dynamics of a supersonic radial jet. Part II

    NASA Astrophysics Data System (ADS)

    Kosarev, V. F.; Klinkov, S. V.; Zaikovskii, V. N.

    2016-05-01

    The paper presents the radial distributions of the pressure measured with a Pitot tube for the case of a radial jet with/without swirling of the input flow in the pre-chamber; the length of the supersonic part of the jet, dependency of the jet thickness as a function of the distance from the nozzle outlet, and approximating analytical formula for the jet thickness that generalizes the experimental data. Experimental data demonstrated that at the deposition distances lower than 4-6 gauges from the nozzle outlet, the solid particle velocity and temperature are almost uniform over the jet cross section. This means that the target surface can be allocated here without loss in coating quality and deposition coefficient. The maximal recommended distance where the deposition is still possible is the length of l s0 ~ 16 gauges.

  3. Combining axial and radial nanowire heterostructures: radial Esaki diodes and tunnel field-effect transistors.

    PubMed

    Dey, Anil W; Svensson, Johannes; Ek, Martin; Lind, Erik; Thelander, Claes; Wernersson, Lars-Erik

    2013-01-01

    The ever-growing demand on high-performance electronics has generated transistors with very impressive figures of merit (Radosavljevic et al., IEEE Int. Devices Meeting 2009, 1-4 and Cho et al., IEEE Int. Devices Meeting 2011, 15.1.1-15.1.4). The continued scaling of the supply voltage of field-effect transistors, such as tunnel field-effect transistors (TFETs), requires the implementation of advanced transistor architectures including FinFETs and nanowire devices. Moreover, integration of novel materials with high electron mobilities, such as III-V semiconductors and graphene, are also being considered to further enhance the device properties (del Alamo, Nature 2011, 479, 317-323, and Liao et al., Nature 2010, 467, 305-308). In nanowire devices, boosting the drive current at a fixed supply voltage or maintaining a constant drive current at a reduced supply voltage may be achieved by increasing the cross-sectional area of a device, however at the cost of deteriorated electrostatics. A gate-all-around nanowire device architecture is the most favorable electrostatic configuration to suppress short channel effects; however, the arrangement of arrays of parallel vertical nanowires to address the drive current predicament will require additional chip area. The use of a core-shell nanowire with a radial heterojunction in a transistor architecture provides an attractive means to address the drive current issue without compromising neither chip area nor device electrostatics. In addition to design advantages of a radial transistor architecture, we in this work illustrate the benefit in terms of drive current per unit chip area and compare the experimental data for axial GaSb/InAs Esaki diodes and TFETs to their radial counterparts and normalize the electrical data to the largest cross-sectional area of the nanowire, i.e. the occupied chip area, assuming a vertical device geometry. Our data on lateral devices show that radial Esaki diodes deliver almost 7 times higher peak

  4. Combining axial and radial nanowire heterostructures: radial Esaki diodes and tunnel field-effect transistors.

    PubMed

    Dey, Anil W; Svensson, Johannes; Ek, Martin; Lind, Erik; Thelander, Claes; Wernersson, Lars-Erik

    2013-01-01

    The ever-growing demand on high-performance electronics has generated transistors with very impressive figures of merit (Radosavljevic et al., IEEE Int. Devices Meeting 2009, 1-4 and Cho et al., IEEE Int. Devices Meeting 2011, 15.1.1-15.1.4). The continued scaling of the supply voltage of field-effect transistors, such as tunnel field-effect transistors (TFETs), requires the implementation of advanced transistor architectures including FinFETs and nanowire devices. Moreover, integration of novel materials with high electron mobilities, such as III-V semiconductors and graphene, are also being considered to further enhance the device properties (del Alamo, Nature 2011, 479, 317-323, and Liao et al., Nature 2010, 467, 305-308). In nanowire devices, boosting the drive current at a fixed supply voltage or maintaining a constant drive current at a reduced supply voltage may be achieved by increasing the cross-sectional area of a device, however at the cost of deteriorated electrostatics. A gate-all-around nanowire device architecture is the most favorable electrostatic configuration to suppress short channel effects; however, the arrangement of arrays of parallel vertical nanowires to address the drive current predicament will require additional chip area. The use of a core-shell nanowire with a radial heterojunction in a transistor architecture provides an attractive means to address the drive current issue without compromising neither chip area nor device electrostatics. In addition to design advantages of a radial transistor architecture, we in this work illustrate the benefit in terms of drive current per unit chip area and compare the experimental data for axial GaSb/InAs Esaki diodes and TFETs to their radial counterparts and normalize the electrical data to the largest cross-sectional area of the nanowire, i.e. the occupied chip area, assuming a vertical device geometry. Our data on lateral devices show that radial Esaki diodes deliver almost 7 times higher peak

  5. Contributing factors for increased bat swing velocity.

    PubMed

    Szymanski, David J; DeRenne, Coop; Spaniol, Frank J

    2009-07-01

    Bat swing velocity is an important characteristic of successful hitters in baseball and softball. The purpose of this literature review is threefold. First, before describing what components and training methods have been investigated to improve bat swing velocity, it is necessary to discuss the importance of bat swing velocity and batted-ball velocity. The second purpose is to discuss bat weight during on-deck circle warm-up, bat weight during resistance training, resistance training with an overload of force, performance of additional supplemental resistance exercises, the relationship between strength, power, lean body mass, and angular velocity and bat swing velocity, and the relationship between improvements in strength, power, lean body mass, and angular velocity and improvements in bat swing velocity. The third purpose of this review is to recommend some practical applications based on research results. PMID:19528868

  6. Contributing factors for increased bat swing velocity.

    PubMed

    Szymanski, David J; DeRenne, Coop; Spaniol, Frank J

    2009-07-01

    Bat swing velocity is an important characteristic of successful hitters in baseball and softball. The purpose of this literature review is threefold. First, before describing what components and training methods have been investigated to improve bat swing velocity, it is necessary to discuss the importance of bat swing velocity and batted-ball velocity. The second purpose is to discuss bat weight during on-deck circle warm-up, bat weight during resistance training, resistance training with an overload of force, performance of additional supplemental resistance exercises, the relationship between strength, power, lean body mass, and angular velocity and bat swing velocity, and the relationship between improvements in strength, power, lean body mass, and angular velocity and improvements in bat swing velocity. The third purpose of this review is to recommend some practical applications based on research results.

  7. Judet type-IV radial neck fractures in children

    PubMed Central

    Kaiser, Margarita; Eberl, Robert; Castellani, Christoph; Kraus, Tanja; Till, Holger; Singer, Georg

    2016-01-01

    Background and purpose Heavily displaced radial neck fractures in children are sometimes associated with poor outcome. A substantial number of these fractures require open reduction. We hypothesized that Judet type-IV fractures with a completely displaced radial head would result in a worse outcome than radial neck fractures with remaining bony contact. Patients and methods We analyzed 19 children (median age 9.7 (4–13) years) who were treated for Judet type-IV radial neck fractures between 2001 and 2014. The outcome was assessed at the latest outpatient visit using the Linscheid-Wheeler score at a median time of 3.5 (1–8) years after injury. The patients were assigned either to group A (9 fractures with remaining bony contact between the radial head and the radial neck) or to group B (10 fractures without any bony contact). Results The 2 groups were similar concerning age and sex. The rate of additional injuries was higher in group B (7/10 vs. 1/9 in group A; p = 0.009). The rate of open reduction was higher in group B (5/10 vs. 0/9 in group A; p = 0.01). Poor outcome was more common in group B (4/10 vs. 0/9 in group A; p = 0.03). In group B, the proportion of children with poor outcome (almost half) was the same irrespective of whether open or closed reduction had been done. Interpretation The main causes of unfavorable results of radial neck fracture in children appear to be related to the energy of the injury and the amount of displacement—and not to whether open reduction was used. PMID:27348024

  8. Toroidal flow and radial particle flux in tokamak plasmas

    NASA Astrophysics Data System (ADS)

    Callen, J. D.; Cole, A. J.; Hegna, C. C.

    2009-08-01

    Many effects influence toroidal flow evolution in tokamak plasmas. Momentum sources and radial plasma transport due to collisional processes and microturbulence-induced anomalous transport are usually considered. In addition, toroidal flow can be affected by nonaxisymmetric magnetic fields; resonant components cause localized electromagnetic toroidal torques near rational surfaces in flowing plasmas and nonresonant components induce "global" toroidal flow damping torque throughout the plasma. Also, poloidal magnetic field transients on the magnetic field diffusion time scale can influence plasma transport. Many of these processes can also produce momentum pinch and intrinsic flow effects. This paper presents a comprehensive and self-consistent description of all these effects within a fluid moment context. Plasma processes on successive time scales (and constraints they impose) are considered sequentially: compressional Alfvén waves (Grad-Shafranov equilibrium and ion radial force balance), sound waves (pressure constant along a field line and incompressible flows within a flux surface), and ion collisions (damping of poloidal flow). Finally, plasma transport across magnetic flux surfaces is induced by the many second order (in the small gyroradius expansion) toroidal torque effects indicated above. Nonambipolar components of the induced particle transport fluxes produce radial plasma currents. Setting the flux surface average of the net radial current induced by all these effects to zero yields the transport-time-scale equation for evolution of the plasma toroidal flow. It includes a combination of global toroidal flow damping and resonant torques induced by nonaxisymmetric magnetic field components, poloidal magnetic field transients, and momentum source effects, as well as the usual collision- and microturbulence-induced transport. On the transport time scale, the plasma toroidal rotation determines the radial electric field for net ambipolar particle transport

  9. PROJECTED ROTATIONAL VELOCITIES OF 136 EARLY B-TYPE STARS IN THE OUTER GALACTIC DISK

    SciTech Connect

    Garmany, C. D.; Glaspey, J. W.; Bragança, G. A.; Daflon, S.; Fernandes, M. Borges; Cunha, K.; Oey, M. S.; Bensby, T.

    2015-08-15

    We have determined projected rotational velocities, v sin i, from Magellan/MIKE echelle spectra for a sample of 136 early B-type stars having large Galactocentric distances. The target selection was done independently of their possible membership in clusters, associations or field stars. We subsequently examined the literature and assigned each star as Field, Association, or Cluster. Our v sin i results are consistent with a difference in aggregate v sin i with stellar density. We fit bimodal Maxwellian distributions to the Field, Association, and Cluster subsamples representing sharp-lined and broad-lined components. The first two distributions, in particular, for the Field and Association are consistent with strong bimodality in v sin i. Radial velocities are also presented, which are useful for further studies of binarity in B-type stars, and we also identify a sample of possible new double-lined spectroscopic binaries. In addition, we find 18 candidate Be stars showing emission at Hα.

  10. Initial drop size and velocity distributions for airblast coaxial atomizers

    NASA Technical Reports Server (NTRS)

    Eroglu, H.; Chigier, N.

    1991-01-01

    Phase Doppler measurements were used to determine initial drop size and velocity distributions after a complete disintegration of coaxial liquid jets. The Sauter mean diameter (SMD) distribution was found to be strongly affected by the structure and behavior of the preceding liquid intact jet. The axial measurement stations were determined from the photographs of the coaxial liquid jet at very short distances (1-2 mm) downstream of the observed break-up locations. Minimum droplet mean velocities were found at the center, and maximum velocities were near the spray boundary. Size-velocity correlations show that the velocity of larger drops did not change with drop size. Drop rms velocity distributions have double peaks whose radial positions coincide with the maximum mean velocity gradients.

  11. IPS observations of the solar wind velocity and the acceleration mechanism

    NASA Technical Reports Server (NTRS)

    Ofman, L.; Davila, J. M.; Coles, W. A.; Grall, R. R.; Klinglesmith, M. T.

    1997-01-01

    Coronal holes are well know sources of high speed solar wind, however, the exact acceleration mechanism of the wind is still unknown. Interplanetary scintillation (IPS) observations indicate that the fast solar wind reaches an average velocity of 800 km s(exp -1) within several solar radii with large velocity fluctuations. However, the origin of the IPS velocity spread below 10 solar radii is unclear. A previously developed coronal home model with a more realistic initial state is applied, and time-dependent, nonlinear, resistive 2.5-DMHD equations are numerically solved. It is found that nonlinear solitary-like waves with a supersonic phase speed are generated in coronal holes by torisonal Alfven waves in the radial flow velocity. The outward propagating nonlinear waves are similar in properties to sound solitons. When these waves are present, the solar wind speed and density fluctuate considerably on a time scale of an hour and on spatial scales of several solar radii in addition to the Alfvenic fluctuations. This is in qualitative agreement with the IPS velocity observations beyond 10 solar radii.

  12. Radially Localized Measurements of Superthermal Electrons Using Obilique Ece

    NASA Astrophysics Data System (ADS)

    Preische, Sherrie Anne

    1995-01-01

    In the effort to design a tokamak which will make a more compact and economically attractive fusion energy reactor, tokamak regimes are envisioned in which radial profiles of the density, temperature, and current are controlled. Lower Hybrid Current Drive is one of the most flexible and proven means of controlling the plasma current profile. In order to develop a better understanding of how, to what extent, and under what conditions LHCD can be used to tailor the current profile, the radial profile and velocity distribution of the fast current-carrying electrons and their time evolution must be known. Spacially localized information about the fast electron distribution function is difficult to obtain. The electron calcitrant resonance, through its sensitivity to the magnetic field as well as to the frequency and angle of observation, provides a means of probing the fast electron distribution function in detail. A new and unique diagnostic has been developed, installed, and operated on the PBX -M tokamak to measure the Electron Cyclotron Emission from these fast electrons. An oblique horizontal view of upshifted cyclotron emission in the midplane gives radial as well as velocity space information about the fast electrons by utilizing the sensitivity of the electron cyclotron resonance. Emission in extraordinary (X)-mode at frequencies refracted by the right-hand cutoff is radially localized. An experiment has been performed in which quasi-X mode emission in the range 60-90 GHz is observed through a focusing gaussian lens antenna at a 57^ circ angle to the toroidal magnetic field. Using the sensitivity of the resonance condition to small changes in frequency and field, radially localized moments. E_ parallel, T_ |, n_{sth}, of the fast electron distribution function are found by a Bayesian analysis method. The evolution of the current profile obtained from these measurements is examined in detail. After the LHCD is turned off, the dynamics are found to be

  13. Radial glia-like cells persist in the adult rat brain.

    PubMed

    Gubert, Fernanda; Zaverucha-do-Valle, Camila; Pimentel-Coelho, Pedro M; Mendez-Otero, Rosalia; Santiago, Marcelo F

    2009-03-01

    During development, radial glia cells contribute to neuronal migration and neurogenesis, and differentiate into astrocytes by the end of the developmental period. Recently, it was demonstrated that during development, radial glia cells, in addition to their role in migration, also give rise to neuroblasts. Furthermore, radial glial cells remain in the adult brain as adult neural stem cells (NSC) in the subventricular zone (SVZ) around the lateral ventricles (LVs), and generate new neurons continuously throughout adulthood. In this study, we used immunohistochemical and morphological methods to investigate the presence of radial glia-like cells around the LVs during the postnatal development period until adulthood in rats. In all ages of rats studied, we identified cells with morphological and immunocytochemical features that are similar to the radial glia cells found in the embryonic brain. Similarly to the radial glia, these cells express nestin and vimentin, and have a radial morphology, extending perpendicularly as processes from the ventricle wall. These cells also express GFAP, GLAST, and Pax6, and proliferate. In the brains of adult rats, we identified cells with relatively long processes (up to 600 mum) in close apposition with migrating neuroblasts. Our results showed that the radial glia-like cells present in the adult rat brain share several morphological and functional characteristics with the embryonic radial glia. We suggest that the embryonic radial glia cells located around the LV walls do not complete their transformation into astrocytes, but rather persist in adulthood.

  14. The Gaussian radial basis function method for plasma kinetic theory

    NASA Astrophysics Data System (ADS)

    Hirvijoki, E.; Candy, J.; Belli, E.; Embréus, O.

    2015-10-01

    Description of a magnetized plasma involves the Vlasov equation supplemented with the non-linear Fokker-Planck collision operator. For non-Maxwellian distributions, the collision operator, however, is difficult to compute. In this Letter, we introduce Gaussian Radial Basis Functions (RBFs) to discretize the velocity space of the entire kinetic system, and give the corresponding analytical expressions for the Vlasov and collision operator. Outlining the general theory, we also highlight the connection to plasma fluid theories, and give 2D and 3D numerical solutions of the non-linear Fokker-Planck equation. Applications are anticipated in both astrophysical and laboratory plasmas.

  15. Development of radially movable multichannel Reynolds stress probe system for a cylindrical laboratory plasma

    SciTech Connect

    Nagashima, Yoshihiko; Yamada, Takuma; Takase, Yuichi; Inagaki, Shigeru; Kamakaki, Kunihiro; Yagi, Masatoshi; Fujisawa, Akihide; Itoh, Sanae-I.; Arakawa, Hiroyuki; Kawai, Yoshinobu; Shinohara, Shunjiro; Itoh, Kimitaka

    2011-03-15

    A new radially movable multichannel azimuthal probe system has been developed for measuring azimuthal and radial profiles of electrostatic Reynolds stress (RS) per mass density of microscale fluctuations for a cylindrical laboratory plasma. The system is composed of 16 probe units arranged azimuthally. Each probe unit has six electrodes to simultaneously measure azimuthal and radial electric fields for obtaining RS. The advantage of the system is that each probe unit is radially movable to measure azimuthal RS profiles at arbitrary radial locations as well as two-dimensional structures of fluctuations. The first result from temporal observation of fluctuation azimuthal profile presents that a low-frequency fluctuation (1-2 kHz) synchronizes oscillating Reynolds stress. In addition, radial scanning of the probe system simultaneously demonstrates two-dimensional patterns of mode structure and nonlinear forces with frequency f= 1.5 kHz and azimuthal mode number m= 1.

  16. Clinical reliability of radial forearm free flap in repair of buccal defects

    PubMed Central

    2013-01-01

    Background The ideal method for buccal defects should provide good outcome of both function and appearance; our goal is to highlight the reliability of radial forearm flap in buccal reconstruction. Methods A retrospective study was conducted. From 2005 to 2012, 20 radial forearm flaps were used to repair the defects. We analyzed the superiority and reliability of the flap; in addition, we reviewed some related literature and made a comparison between radial forearm flap and platysma flap. Results All radial forearm flaps totally survived, but two flaps suffered venous obstruction, hematoma, respectively. Radial forearm flap preserved the original interincisal distance well. In our follow-up, all patients had sufficient mouth-opening width (mean: 4.3 cm). Conclusion Radial forearm flap is a reliable method for buccal defect reconstruction. PMID:23363472

  17. Velocity structure of the NE Tibetan Plateau: P and S body wave tomographic model of the northeastern Tibetan Plateau and its margins with additional constraints from surface wave tomography

    NASA Astrophysics Data System (ADS)

    Nunn, C.; Roecker, S. W.; Tilmann, F. J.; Priestley, K. F.; Heyburn, R.; Mechie, J.; Sandvol, E. A.; Ni, J. F.; Chen, Y. J.; Zhao, W.

    2012-12-01

    The northeastern margin of the Tibetan plateau, which includes the Qiangtang and Songpan-Ganzi terranes as well as the Kunlun Shan and part of the Qaidam basin, continues to uplift and deform in response to the ongoing India-Eurasia collision. To test competing hypotheses concerning the mechanisms for this deformation, we assembled a high quality data set of more than 19,000 P- and 3,500 S-wave arrival times from earthquakes at teleseismic distances from the INDEPTH-IV and ASCENT broadband seismometer deployments. We analyze these arrival times to construct tomographic images of P- and S-wave velocities in the crust and upper mantle beneath this part of the plateau. Starting models for these inversions are generated from a combination of results from recent surface wave investigations and Moho depth maps from receiver function studies. We find that our results are largely insensitive to the choice of starting model, especially at depths greater than 125 km. Nevertheless, the incorporation of surface wave models considerably aids our interpretation of the body wave based images. Resolution tests indicate that features of 150 km length scale are reliably imaged throughout the study region, and at smaller scale in areas of good coverage, but with significant smearing in the vertical direction. Our results suggest that, south of the Qaidam basin, the underthrusting Indian plate is sub-horizontal, at least 100 km thick, and below depths of ~140km. The lower part of the Indian plate is likely to reach as far north as ~34.5°, which corresponds to the Jinsha Suture in the west and the South Kunlun Fault in the east. A structure previously thought to be down-welling Indian lithosphere is resolved in our images into two separate fast wavespeed anomalies. We see no evidence of southward-directed subduction of the Qaidam basin under the Tibetan plateau. Our models corroborate results of previous work which imaged a relatively slow wavespeed region between the basin and the

  18. The peculiar velocities of rich clusters in the hot and cold dark matter scenarios

    NASA Technical Reports Server (NTRS)

    Rhee, George F.; West, Michael J.; Villumsen, Jens V.

    1993-01-01

    We present the results of a study of the peculiar velocities of rich clusters of galaxies. The peculiar motion of rich clusters in various cosmological scenarios is of interest for a number of reasons. Observationally, one can measure the peculiar motion of clusters to greater distances than galaxies because cluster peculiar motions can be determined to greater accuracy. One can also test the slope of distance indicator relations using clusters to see if galaxy properties vary with environment. We have used N-body simulations to measure the amplitude and rms cluster peculiar velocity as a function of bias parameter in the hot and cold dark matter scenarios. In addition to measuring the mean and rms peculiar velocity of clusters in the two models, we determined whether the peculiar velocity vector of a given cluster is well aligned with the gravity vector due to all the particles in the simulation and the gravity vector due to the particles present only in the clusters. We have investigated the peculiar velocities of rich clusters of galaxies in the cold dark matter and hot dark matter galaxy formation scenarios. We have derived peculiar velocities and associated errors for the scenarios using four values of the bias parameter ranging from b = 1 to b = 2.5. The growth of the mean peculiar velocity with scale factor has been determined and compared to that predicted by linear theory. In addition, we have compared the orientation of force and velocity in these simulations to see if a program such as that proposed by Bertschinger and Dekel (1989) for elliptical galaxy peculiar motions can be applied to clusters. The method they describe enables one to recover the density field from large scale redshift distance samples. The method makes it possible to do this when only radial velocities are known by assuming that the velocity field is curl free. Our analysis suggests that this program if applied to clusters is only realizable for models with a low value of the bias

  19. ULF Waves and Diffusive Radial Transport of Charged Particles

    NASA Astrophysics Data System (ADS)

    Ali, Ashar Fawad

    field data from the Radiation Belt Storm Probes (RBSP) to compute the electric and the magnetic component of the radial diffusion coefficient using the Fei et al. [2006] formulation. We conclude that contrary to prior notions, the electric component is dominant in driving radial diffusion of charged particles in the Earth's inner magnetosphere instead of the magnetic component. The electric component can be up to two orders of magnitude larger than the magnetic component. In addition, we see that ULF wave power in both the electric and the magnetic fields has a clear dependence on Kp with wave power decreasing as radial distance decreases. For both fields, the noon sectors generally contain more ULF wave power than the dawn, dusk, and the midnight magnetic local time (MLT) sectors. There is no significant difference between ULF wave power in the dawn, dusk, and the midnight sectors.

  20. Radial superlattices and single nanoreactors

    NASA Astrophysics Data System (ADS)

    Deneke, Ch.; Jin-Phillipp, N.-Y.; Loa, I.; Schmidt, O. G.

    2004-05-01

    We investigate the wall structure and thermal stability of individual freestanding rolled-up nanotubes (RUNTs) using micro-Raman spectroscopy, transmission electron microscopy, and selected area electron diffraction. Our studies reveal that the walls of the InAs/GaAs RUNTs consist of a radial superlattice comprising alternating crystalline and noncrystalline layers. Furthermore, we locally heated individual RUNTs with a laser beam, and Raman spectroscopy was used in situ to monitor any structural changes. At about 300 °C the heated part of a RUNT starts to oxidize and eventually transforms into crystalline β-Ga2O3. This result shows that RUNTs can serve as nanoreactors that locally synthesize material at intentional places on a substrate surface.

  1. Modeling anomalous radial transport in kinetic transport codes

    NASA Astrophysics Data System (ADS)

    Bodi, K.; Krasheninnikov, S. I.; Cohen, R. H.; Rognlien, T. D.

    2009-11-01

    Anomalous transport is typically the dominant component of the radial transport in magnetically confined plasmas, where the physical origin of this transport is believed to be plasma turbulence. A model is presented for anomalous transport that can be used in continuum kinetic edge codes like TEMPEST, NEO and the next-generation code being developed by the Edge Simulation Laboratory. The model can also be adapted to particle-based codes. It is demonstrated that the model with a velocity-dependent diffusion and convection terms can match a diagonal gradient-driven transport matrix as found in contemporary fluid codes, but can also include off-diagonal effects. The anomalous transport model is also combined with particle drifts and a particle/energy-conserving Krook collision operator to study possible synergistic effects with neoclassical transport. For the latter study, a velocity-independent anomalous diffusion coefficient is used to mimic the effect of long-wavelength ExB turbulence.

  2. A radially resolved kinetic model for nonlocal electron ripple diffusion losses in tokamaks

    SciTech Connect

    Robertson, Scott

    2006-09-15

    A relatively simple radially resolved kinetic model is applied to the ripple diffusion problem for electrons in tokamaks. The distribution function f(r,v) is defined on a two-dimensional grid, where r is the radial coordinate and v is the velocity coordinate. Particle transport in the radial direction is from ripple and banana diffusion and transport in the velocity direction is described by the Fokker-Planck equation. Particles and energy are replaced by source functions that are adjusted to maintain a constant central density and temperature. The relaxed profiles of f(r,v) show that the electron distribution function at the wall contains suprathermal electrons that have diffused from the interior that enhance ripple transport. The transport at the periphery is therefore nonlocal. The energy replacement times from the computational model are near to the experimental replacement times for tokamak discharges in the compilation by Pfeiffer and Waltz [Nucl. Fusion 19, 51 (1979)].

  3. Three-dimensional Distribution of Azimuthal and Radial Anisotropy in the Japan Subduction

    NASA Astrophysics Data System (ADS)

    Ishise, M.; Kawakatsu, H.; Shiomi, K.

    2014-12-01

    Seismic anisotropy has close relationships with past and present tectonic and dynamic processes. Therefore, detailed description of seismic anisotropy of subduction zones provides important information for our understanding of the subduction system. The most common method of detecting anisotropy is the S-wave splitting measurement. However, conventional S-wave splitting analysis is not an appropriate way to investigate anisotropy in the mantle and slab because the technique has no vertical resolution. Thus, we have improved common traveltime tomography to estimate three-dimensional anisotropic structures of P-wave, assuming that the modeling space is composed of weakly anisotropic medium with a hexagonal symmetry about a horizontal axis (Ishise & Oda, 2005, JGR; Ishise & Oda, 2008, PEPI). Recently, we extended the anisotropic tomography for P-wave radial anisotropy with vertical hexagonal symmetry axis (Ishise & Kawakatsu, 2012 JpGU). In this study, we expand the study area of our previous regional analyses of P-wave azimuthal and radial anisotropic tomography (Ishise & Oda, 2005; Ishise & Kawakatsu, 2012, JpGU; Ishise et al., 2012, SSJ) using Hi-net arrival time data and examine the subduction system around the Japan islands, where two trenches with different strike directions and plate junction are included. Here are some of the remarkable results associated with the PAC slab and mantle structure. (1) N-S-trending fast axis of P-wave anisotropy is dominant in the PAC slab. (2) the mantle wedge shows trench-normal anisotropy across the trench-trench junction. (3) horizontal velocity (PH) tends to be faster than vertical velocity (PV) in the slab. (4) PV tends to be faster than PH in the mantle wedge. The characteristics of the obtained azimuthal and radial anisotropy of the PAC slab and the mantle wedge qualitatively consistent with heterogeneous plate models (e.g., Furumura & Kennet, 2005) and numerical simulations of mantle flow (Morishige & Honda, 2011; 2013

  4. Outcome of Radial Head Arthroplasty in Comminuted Radial Head Fractures: Short and Midterm Results

    PubMed Central

    Moghaddam, Arash; Raven, Tim Friedrich; Dremel, Eike; Studier-Fischer, Stefan; Grutzner, Paul Alfred; Biglari, Bahram

    2016-01-01

    moderate or severe periarticular ossification, and scored substantially worse according to MEPI and Morrey. Four patients required revisional surgery due to loosening of the prosthesis and chronic pain. In addition, one patient required a neurolysis of the ulnaris nerve, one developed a neobursa, and one had extensive swelling and blistering. The time interval between injury and treatment appeared to have an effect on results. Thirty-five patients were treated within the first 5 days after accident and showed better results than the 40 patients who were treated after 5 days. Conclusions: Comminuted radial head fractures with elbow instability can be treated well with a modular radial head prosthesis, which restores stability in acute treatment. The modular radial head arthroplasty used in this study showed promising findings in short to midterm results. PMID:27218046

  5. Stirling Engine With Radial Flow Heat Exchangers

    NASA Technical Reports Server (NTRS)

    Vitale, N.; Yarr, George

    1993-01-01

    Conflict between thermodynamical and structural requirements resolved. In Stirling engine of new cylindrical configuration, regenerator and acceptor and rejector heat exchangers channel flow of working gas in radial direction. Isotherms in regenerator ideally concentric cylinders, and gradient of temperature across regenerator radial rather than axial. Acceptor and rejector heat exchangers located radially inward and outward of regenerator, respectively. Enables substantial increase in power of engine without corresponding increase in diameter of pressure vessel.

  6. Hollow Cathode With Multiple Radial Orifices

    NASA Technical Reports Server (NTRS)

    Brophy, John R.

    1992-01-01

    Improved hollow cathode serving as source of electrons has multiple radial orifices instead of single axial orifice. Distributes ion current more smoothly, over larger area. Prototype of high-current cathodes for ion engines in spacecraft. On Earth, cathodes used in large-diameter ion sources for industrial processing of materials. Radial orientation of orifices in new design causes current to be dispersed radially in vicinity of cathode. Advantageous where desireable to produce plasma more nearly uniform over wider region around cathode.

  7. Evidence for dust-driven, radial plasma transport in Saturn's inner radiation belts

    NASA Astrophysics Data System (ADS)

    Roussos, E.; Krupp, N.; Kollmann, P.; Paranicas, C.; Mitchell, D. G.; Krimigis, S. M.; Andriopoulou, M.

    2016-08-01

    A survey of Cassini MIMI/LEMMS data acquired between 2004 and 2015 has led to the identification of 13 energetic electron microsignatures that can be attributed to particle losses on one of the several faint rings of the planet. Most of the signatures were detected near L-shells that map between the orbits of Mimas and Enceladus or near the G-ring. Our analysis indicates that it is very unlikely for these signatures to have originated from absorption on Mimas, Enceladus or unidentified Moons and rings, even though most were not found exactly at the L-shells of the known rings of the saturnian system (G-ring, Methone, Anthe, Pallene). The lack of additional absorbers is apparent in the L-shell distribution of MeV ions which are very sensitive for tracing the location of weakly absorbing material permanently present in Saturn's radiation belts. This sensitivity is demonstrated by the identification, for the first time, of the proton absorption signatures from the asteroid-sized Moons Pallene, Anthe and/or their rings. For this reason, we investigate the possibility that the 13 energetic electron events formed at known saturnian rings and the resulting depletions were later displaced radially by one or more magnetospheric processes. Our calculations indicate that the displacement magnitude for several of those signatures is much larger than the one that can be attributed to radial flows imposed by the recently discovered noon-to-midnight electric field in Saturn's inner magnetosphere. This observation is consistent with a mechanism where radial plasma velocities are enhanced near dusty obstacles. Several possibilities are discussed that may explain this observation, including a dust-driven magnetospheric interchange instability, mass loading by the pick-up of nanometer charged dust grains and global magnetospheric electric fields induced by perturbed orbits of charged dust due to the act of solar radiation pressure. Indirect evidence for a global scale interaction

  8. Radial Wettable Gradient of Hot Surface to Control Droplets Movement in Directions

    PubMed Central

    Feng, Shile; Wang, Sijie; Tao, Yuanhao; Shang, Weifeng; Deng, Siyan; Zheng, Yongmei; Hou, Yongping

    2015-01-01

    A radial wettable gradient was fabricated on the surface of graphite plate by a simple one-step anodic oxidation process. It was found that the direction and value of the wettable gradient could be easily controlled by adjusting current and oxidation time gradient. With the increase of surface temperature, droplets on surface not only exhibited the transition of boiling mode, but also showed the controlled radial spreading, evaporation and movement behaviors. These phenomena could be attributed to the cooperation of wettability force, hysteresis force and vapor pressure (Leidenfrost effect). Especially, the controlled radial convergence or divergence of droplets with high velocity were realized on the surfaces with either inside or outside radial gradient, which would have crucial applications in the design of microfluidic devices and the exploration of the biotechnology. PMID:25975722

  9. Radial liquid crystal alignment based on circular rubbing of a substrate coated with poly(N-vinyl carbazole) film

    NASA Astrophysics Data System (ADS)

    Chen, Yuan-Di; Ying-Guey Fuh, Andy; Liu, Cheng-Kai; Cheng, Ko-Ting

    2011-06-01

    This paper presents a simple method to produce radial liquid crystal (LC) alignment layers using circular rubbing of poly(N-vinyl carbazole) (PVK) films. The produced layer can be used for fabricating axially symmetric homogeneous-radial, homeotropic-radial and radial-radial LC alignment devices by combining a rubbed PVK-coated substrate with another one with a desired LC alignment layer. The transmittance-voltage curves of the fabricated LC devices at various positions are measured to examine the uniformity of the alignment effect. Additionally, the PVK film does not absorb visible light, and can be operated at high temperatures.

  10. Velocity fluctuations of fission fragments

    NASA Astrophysics Data System (ADS)

    Llanes-Estrada, Felipe J.; Carmona, Belén Martínez; Martínez, Jose L. Muñoz

    2016-02-01

    We propose event by event velocity fluctuations of nuclear fission fragments as an additional interesting observable that gives access to the nuclear temperature in an independent way from spectral measurements and relates the diffusion and friction coefficients for the relative fragment coordinate in Kramers-like models (in which some aspects of fission can be understood as the diffusion of a collective variable through a potential barrier). We point out that neutron emission by the heavy fragments can be treated in effective theory if corrections to the velocity distribution are needed.

  11. Robust, automatic GPS station velocities and velocity time series

    NASA Astrophysics Data System (ADS)

    Blewitt, G.; Kreemer, C.; Hammond, W. C.

    2014-12-01

    Automation in GPS coordinate time series analysis makes results more objective and reproducible, but not necessarily as robust as the human eye to detect problems. Moreover, it is not a realistic option to manually scan our current load of >20,000 time series per day. This motivates us to find an automatic way to estimate station velocities that is robust to outliers, discontinuities, seasonality, and noise characteristics (e.g., heteroscedasticity). Here we present a non-parametric method based on the Theil-Sen estimator, defined as the median of velocities vij=(xj-xi)/(tj-ti) computed between all pairs (i, j). Theil-Sen estimators produce statistically identical solutions to ordinary least squares for normally distributed data, but they can tolerate up to 29% of data being problematic. To mitigate seasonality, our proposed estimator only uses pairs approximately separated by an integer number of years (N-δt)<(tj-ti )<(N+δt), where δt is chosen to be small enough to capture seasonality, yet large enough to reduce random error. We fix N=1 to maximally protect against discontinuities. In addition to estimating an overall velocity, we also use these pairs to estimate velocity time series. To test our methods, we process real data sets that have already been used with velocities published in the NA12 reference frame. Accuracy can be tested by the scatter of horizontal velocities in the North American plate interior, which is known to be stable to ~0.3 mm/yr. This presents new opportunities for time series interpretation. For example, the pattern of velocity variations at the interannual scale can help separate tectonic from hydrological processes. Without any step detection, velocity estimates prove to be robust for stations affected by the Mw7.2 2010 El Mayor-Cucapah earthquake, and velocity time series show a clear change after the earthquake, without any of the usual parametric constraints, such as relaxation of postseismic velocities to their preseismic values.

  12. Radial-Electric-Field Piezoelectric Diaphragm Pumps

    NASA Technical Reports Server (NTRS)

    Bryant, Robert G.; Working, Dennis C.; Mossi, Karla; Castro, Nicholas D.; Mane, Pooma

    2009-01-01

    In a recently invented class of piezoelectric diaphragm pumps, the electrode patterns on the piezoelectric diaphragms are configured so that the electric fields in the diaphragms have symmetrical radial (along-the-surface) components in addition to through-the-thickness components. Previously, it was accepted in the piezoelectric-transducer art that in order to produce the out-of-plane bending displacement of a diaphragm needed for pumping, one must make the electric field asymmetrical through the thickness, typically by means of electrodes placed on only one side of the piezoelectric material. In the present invention, electrodes are placed on both sides and patterned so as to produce substantial radial as well as through-the-thickness components. Moreover, unlike in the prior art, the electric field can be symmetrical through the thickness. Tests have shown in a given diaphragm that an electrode configuration according to this invention produces more displacement than does a conventional one-sided electrode pattern. The invention admits of numerous variations characterized by various degrees of complexity. Figure 1 is a simplified depiction of a basic version. As in other piezoelectric diaphragm pumps of similar basic design, the prime mover is a piezoelectric diaphragm. Application of a suitable voltage to the electrodes on the diaphragm causes it to undergo out-of-plane bending. The bending displacement pushes a fluid out of, or pulls the fluid into, a chamber bounded partly by the diaphragm. Also as in other diaphragm pumps in general, check valves ensure that the fluid flows only in through one port and only out through another port.

  13. The Importance of Radial Migration to the Evolution of Spiral Galaxies

    NASA Astrophysics Data System (ADS)

    Daniel, Kathryne J.; Wyse, Rosemary F. G.

    2016-01-01

    Spiral galaxy evolution is frequently considered in the context of environment, but internal processes may also play an important role. Radial migration is one such internal process, wherein a transient spiral arm rearranges the angular momentum distribution of the disk around corotation without causing kinematic heating. The efficiency of radial migration depends on both the duty cycle for transient patterns and the RMS change in orbital angular momentum induced by each pattern. Should radial migration be efficient, it could cause a substantial fraction of disk stars to move large radial distances over the lifetime of the disk, thus having significant impact on its kinematic, structural and chemical evolution.In this talk, I will summarize a subset of work focusing on the physics that determines the magnitude of the RMS change in orbital angular momentum from each spiral pattern. I have derived an analytic "capture criterion" that predicts whether or not a disk star with finite random orbital energy is in a "trapped orbit" (i.e. the orbital family induced by the spiral pattern that can lead to radial migration). I will present this criterion and show that it is primarily a star's orbital angular momentum that determines whether or not it is in a trapped orbit. The capture criterion could be used to better understand the role of radial migration in N-body simulations as well as applied to models of galaxy evolution. I will describe an example study wherein I applied the capture criterion, in a series of disk galaxy models, to find the fraction of an ensemble of stars that is in trapped orbits. I found that this fraction decreases linearly with increasing radial velocity dispersion and conclude that radial migration may play a role in the evolution of disk galaxies, but it is insignificant to the evolution of high velocity dispersion populations.

  14. The influence of collisional and anomalous radial diffusion on parallel ion transport in edge plasmas

    SciTech Connect

    Helander, P.; Hazeltine, R.D.; Catto, P.J.

    1996-12-31

    The orderings in the kinetic equations commonly used to study the plasma core of a tokamak do not allow a balance between parallel ion streaming and radial diffusion, and are, therefore, inappropriate in the plasma edge. Different orderings are required in the edge region where radial transport across the steep gradients associated with the scrape-off layer is large enough to balance the rapid parallel flow caused by conditions close to collecting surfaces (such as the Bohm sheath condition). In the present work, we derive and solve novel kinetic equations, allowing for such a balance, and construct distinctive transport laws for impure, collisional, edge plasmas in which the perpendicular transport is (i) due to Coulomb collisions of ions with heavy impurities, or (ii) governed by anomalous diffusion driven by electrostatic turbulence. In both the collisional and anomalous radial transport cases, we find that one single diffusion coefficient determines the radial transport of particles, momentum and heat. The parallel transport laws and parallel thermal force in the scrape-off layer assume an unconventional form, in which the relative ion-impurity flow is driven by a combination of the conventional parallel gradients, and new (i) collisional or (ii) anomalous terms involving products of radial derivatives of the temperature and density with the radial shear of the parallel velocity. Thus, in the presence of anomalous radial diffusion, the parallel ion transport cannot be entirely classical, as usually assumed in numerical edge computations. The underlying physical reason is the appearance of a novel type of parallel thermal force resulting from the combined action of anomalous diffusion and radial temperature and velocity gradients. In highly sheared flows the new terms can modify impurity penetration into the core plasma.

  15. Relationship between radial and central arterial pulse wave and evaluation of central aortic pressure using the radial arterial pulse wave.

    PubMed

    Takazawa, Kenji; Kobayashi, Hideyuki; Shindo, Naohisa; Tanaka, Nobuhiro; Yamashina, Akira

    2007-03-01

    Since a decrease of central aortic pressure contributes to the prevention of cardiovascular events, simple measurement of not only brachial blood pressure but also central aortic pressure may be useful in the prevention and treatment of cardiovascular diseases. In this study, we simultaneously measured radial artery pulse waves non-invasively and ascending aortic pressure invasively, before and after the administration of nicorandil. We then compared changes in central aortic pressure and radial arterial blood pressure calibrated with brachial blood pressure in addition to calculating the augmentation index (AI) at the aorta and radial artery. After nicorandil administration, the reduction in maximal systolic blood pressure in the aorta (Deltaa-SBP) was -14+/-15 mmHg, significantly larger than that in early systolic pressure in the radial artery (Deltar-SBP) (-9+/-12 mmHg). The reduction in late systolic blood pressure in the radial artery (Deltar-SBP2) was -15+/-14 mmHg, significantly larger than Deltar-SBP, but not significantly different from Deltaa-SBP. There were significant relationships between Deltaa-SBP and Deltar-SBP (r=0.81, p<0.001), and between Deltaa-SBP and Deltar-SBP2 (r=0.91, p<0.001). The slope of the correlation regression line with Deltar-SBP2 (0.83) was larger and closer to 1 than that with Deltar-SBP (0.63), showing that the relationship was close to 1:1. Significant correlations were obtained between aortic AI (a-AI) and radial AI (r-AI) (before nicorandil administration: r=0.91, p<0.001; after administration: r=0.70, p<0.001). These data suggest that the measurement of radial artery pulse wave and observation of changes in the late systolic blood pressure in the radial artery (r-SBP2) in addition to the ordinary measurement of brachial blood pressure may enable a more accurate evaluation of changes in maximal systolic blood pressure in the aorta (a-SBP).

  16. POTENT Reconstruction from Mark III Velocities

    NASA Astrophysics Data System (ADS)

    Dekel, A.; Eldar, A.; Kolatt, T.; Yahil, A.; Willick, J. A.; Faber, S. M.; Courteau, S.; Burstein, D.

    1999-09-01

    We present an improved version of the POTENT method for reconstructing the cosmological velocity and mass density fields from radial peculiar velocities, test it with mock catalogs, and apply it to the Mark III Catalog of Galaxy Peculiar Velocities. The method is improved in several ways: (1) the inhomogeneous Malmquist bias is reduced by grouping and corrected statistically in either forward or inverse analyses of inferred distances, (2) the smoothing into a radial velocity field is optimized such that window and sampling biases are reduced, (3) the density field is derived from the velocity field using an improved weakly nonlinear approximation in Eulerian space, and (4) the computational errors are made negligible compared to the other errors. The method is carefully tested and optimized using realistic mock catalogs based on an N-body simulation that mimics our cosmological neighborhood, and the remaining systematic and random errors are evaluated quantitatively. The Mark III catalog, with ~3300 grouped galaxies, allows a reliable reconstruction with fixed Gaussian smoothing of 10-12 h-1 Mpc out to ~60 h-1 Mpc and beyond in some directions. We present maps of the three-dimensional velocity and mass-density fields and the corresponding errors. The typical systematic and random errors in the density fluctuations inside 40 h-1 Mpc are +/-0.13 and +/-0.18 (for Ω=1). In its gross features, the recovered mass distribution resembles the galaxy distribution in redshift surveys and the mass distribution in a similar POTENT analysis of a complementary velocity catalog (SFI), including such features as the Great Attractor, Perseus-Pisces, and the large void in between. The reconstruction inside ~40 h-1 Mpc is not affected much by a revised calibration of the distance indicators (VM2, tailored to match the velocities from the IRAS 1.2 Jy redshift survey). The volume-weighted bulk velocity within the sphere of radius 50 h-1 Mpc about the Local Group is V50=370+/-110 km s-1

  17. Weighing Rocky Exoplanets with Improved Radial Velocimetry

    NASA Astrophysics Data System (ADS)

    Xuesong Wang, Sharon; Wright, Jason; California Planet Survey Consortium

    2016-01-01

    The synergy between Kepler and the ground-based radial velocity (RV) surveys have made numerous discoveries of small and rocky exoplanets, opening the age of Earth analogs. However, most (29/33) of the RV-detected exoplanets that are smaller than 3 Earth radii do not have their masses constrained to better than 20% - limited by the current RV precision (1-2 m/s). Our work improves the RV precision of the Keck telescope, which is responsible for most of the mass measurements for small Kepler exoplanets. We have discovered and verified, for the first time, two of the dominant terms in Keck's RV systematic error budget: modeling errors (mostly in deconvolution) and telluric contamination. These two terms contribute 1 m/s and 0.6 m/s, respectively, to the RV error budget (RMS in quadrature), and they create spurious signals at periods of one sidereal year and its harmonics with amplitudes of 0.2-1 m/s. Left untreated, these errors can mimic the signals of Earth-like or Super-Earth planets in the Habitable Zone. Removing these errors will bring better precision to ten-year worth of Keck data and better constraints on the masses and compositions of small Kepler planets. As more precise RV instruments coming online, we need advanced data analysis tools to overcome issues like these in order to detect the Earth twin (RV amplitude 8 cm/s). We are developing a new, open-source RV data analysis tool in Python, which uses Bayesian MCMC and Gaussian processes, to fully exploit the hardware improvements brought by new instruments like MINERVA and NASA's WIYN/EPDS.

  18. Radial head button holing: a cause of irreducible anterior radial head dislocation.

    PubMed

    Shin, Su-Mi; Chai, Jee Won; You, Ja Yeon; Park, Jina; Bae, Kee Jeong

    2016-10-01

    "Buttonholing" of the radial head through the anterior joint capsule is a known cause of irreducible anterior radial head dislocation associated with Monteggia injuries in pediatric patients. To the best of our knowledge, no report has described an injury consisting of buttonholing of the radial head through the annular ligament and a simultaneous radial head fracture in an adolescent. In the present case, the radiographic findings were a radial head fracture with anterior dislocation and lack of the anterior fat pad sign. Magnetic resonance imaging (MRI) clearly demonstrated anterior dislocation of the fractured radial head through the torn annular ligament. The anterior joint capsule and proximal portion of the annular ligament were interposed between the radial head and capitellum, preventing closed reduction of the radial head. Familiarity with this condition and imaging findings will aid clinicians to make a proper diagnosis and fast decision to perform an open reduction. PMID:27502623

  19. Radial Domany-Kinzel models with mutation and selection

    NASA Astrophysics Data System (ADS)

    Lavrentovich, Maxim O.; Korolev, Kirill S.; Nelson, David R.

    2013-01-01

    We study the effect of spatial structure, genetic drift, mutation, and selective pressure on the evolutionary dynamics in a simplified model of asexual organisms colonizing a new territory. Under an appropriate coarse-graining, the evolutionary dynamics is related to the directed percolation processes that arise in voter models, the Domany-Kinzel (DK) model, contact process, and so on. We explore the differences between linear (flat front) expansions and the much less familiar radial (curved front) range expansions. For the radial expansion, we develop a generalized, off-lattice DK model that minimizes otherwise persistent lattice artifacts. With both simulations and analytical techniques, we study the survival probability of advantageous mutants, the spatial correlations between domains of neutral strains, and the dynamics of populations with deleterious mutations. “Inflation” at the frontier leads to striking differences between radial and linear expansions. For a colony with initial radius R0 expanding at velocity v, significant genetic demixing, caused by local genetic drift, occurs only up to a finite time t*=R0/v, after which portions of the colony become causally disconnected due to the inflating perimeter of the expanding front. As a result, the effect of a selective advantage is amplified relative to genetic drift, increasing the survival probability of advantageous mutants. Inflation also modifies the underlying directed percolation transition, introducing novel scaling functions and modifications similar to a finite-size effect. Finally, we consider radial range expansions with deflating perimeters, as might arise from colonization initiated along the shores of an island.

  20. Bayesian inference of Earth's radial seismic structure from body-wave traveltimes using neural networks

    NASA Astrophysics Data System (ADS)

    de Wit, Ralph W. L.; Valentine, Andrew P.; Trampert, Jeannot

    2013-10-01

    How do body-wave traveltimes constrain the Earth's radial (1-D) seismic structure? Existing 1-D seismological models underpin 3-D seismic tomography and earthquake location algorithms. It is therefore crucial to assess the quality of such 1-D models, yet quantifying uncertainties in seismological models is challenging and thus often ignored. Ideally, quality assessment should be an integral part of the inverse method. Our aim in this study is twofold: (i) we show how to solve a general Bayesian non-linear inverse problem and quantify model uncertainties, and (ii) we investigate the constraint on spherically symmetric P-wave velocity (VP) structure provided by body-wave traveltimes from the EHB bulletin (phases Pn, P, PP and PKP). Our approach is based on artificial neural networks, which are very common in pattern recognition problems and can be used to approximate an arbitrary function. We use a Mixture Density Network to obtain 1-D marginal posterior probability density functions (pdfs), which provide a quantitative description of our knowledge on the individual Earth parameters. No linearization or model damping is required, which allows us to infer a model which is constrained purely by the data. We present 1-D marginal posterior pdfs for the 22 VP parameters and seven discontinuity depths in our model. P-wave velocities in the inner core, outer core and lower mantle are resolved well, with standard deviations of ˜0.2 to 1 per cent with respect to the mean of the posterior pdfs. The maximum likelihoods of VP are in general similar to the corresponding ak135 values, which lie within one or two standard deviations from the posterior means, thus providing an independent validation of ak135 in this part of the radial model. Conversely, the data contain little or no information on P-wave velocity in the D'' layer, the upper mantle and the homogeneous crustal layers. Further, the data do not constrain the depth of the discontinuities in our model. Using additional

  1. Estimating wave orbital velocity through the azimuth cutoff from space-borne satellites

    NASA Astrophysics Data System (ADS)

    Stopa, Justin E.; Ardhuin, Fabrice; Chapron, Bertrand; Collard, Fabrice

    2015-11-01

    It has been long accepted that ocean wave conditions recorded from synthetic aperture radar (SAR) aboard satellites resolve large scale swells. SARs make use of its displacement to achieve fine resolution; however the random surface motions can reduce its nominal azimuthal resolution. Accordingly, the SAR spectral azimuth response mirrors the probability distribution of the radial velocity component of the scatters. This effect, quantified in a measure called the azimuth cutoff, is estimated by defining a scale based on the fitting of a Gaussian function to the radar cross section azimuth spectrum. The independent measure provides additional sea state information related to the root mean square surface orbital wave velocity. We use data recorded from the European Space Agency's ENVISAT advanced SAR in the C-band spanning its lifetime 2003-2012. Our purpose is to first establish the validity of the azimuth cutoff using both colocated buoys and modeled wave data. Some systematic biases are corrected using other SAR derived parameters, improving the accuracy of the estimate. Despite our efforts, errors exist in the presence of swell, extreme wind waves, and related to the wave direction. Under the majority of the sea states the parameter is well behaved. As a final point, applications using the wave orbital velocities are described in terms of diagnosing a spectral wave model and the wave climate. As illustrated, the returned radar signal provides useful sea state information that resolves wind speeds, wave orbital velocities from the wind waves, and swells.

  2. HYBRID COSMOLOGICAL SIMULATIONS WITH STREAM VELOCITIES

    SciTech Connect

    Richardson, Mark L. A.; Scannapieco, Evan; Thacker, Robert J.

    2013-07-10

    In the early universe, substantial relative ''stream'' velocities between the gas and dark matter arise due to radiation pressure and persist after recombination. To assess the impact of these velocities on high-redshift structure formation, we carry out a suite of high-resolution adaptive mesh refinement (AMR) cosmological simulations, which use smoothed particle hydrodynamic data sets as initial conditions, converted using a new tool developed for this work. These simulations resolve structures with masses as small as a few 100 M{sub Sun }, and we focus on the 10{sup 6} M{sub Sun} ''mini-halos'' in which the first stars formed. At z Almost-Equal-To 17, the presence of stream velocities has only a minor effect on the number density of halos below 10{sup 6} M{sub Sun }, but it greatly suppresses gas accretion onto all halos and the dark matter structures around them. Stream velocities lead to significantly lower halo gas fractions, especially for Almost-Equal-To 10{sup 5} M{sub Sun} objects, an effect that is likely to depend on the orientation of a halo's accretion lanes. This reduction in gas density leads to colder, more compact radial profiles, and it substantially delays the redshift of collapse of the largest halos, leading to delayed star formation and possibly delayed reionization. These many differences suggest that future simulations of early cosmological structure formation should include stream velocities to properly predict gas evolution, star formation, and the epoch of reionization.

  3. Copernicus observations of Iota Herculis velocity variations

    NASA Technical Reports Server (NTRS)

    Rogerson, J. B., Jr.

    1984-01-01

    Observations of Iota Her at 109.61-109.67 nm obtained with the U1 channel of the Copernicus spectrophotometer at resolution 5 pm during 3.6 days in May, 1979, are reported. Radial-velocity variations are detected and analyzed as the sum of two sinusoids with frequencies 0.660 and 0.618 cycles/day and amplitudes 9.18 and 8.11 km/s, respectively. Weak evidence supporting the 13.9-h periodicity seen in line-profile variations by Smith (1978) is found.

  4. Improving the radial nerve neurodynamic test: An observation of tension of the radial, median and ulnar nerves during upper limb positioning.

    PubMed

    Manvell, Joshua J; Manvell, Nicole; Snodgrass, Suzanne J; Reid, Susan A

    2015-12-01

    The radial nerve neurodynamic test (ULNT2b), used to implicate symptoms arising from the radial nerve, is proposed to selectively increase strain of the nerve without increasing strain of adjacent tissue, though this has not been established. This study aimed to determine the upper limb position that results in: (1) the greatest tension of the radial nerve and (2) the greatest difference in tension between the radial nerve and the other two major nerves of the upper limb: median and ulnar. Tension (N) of the radial, median and ulnar nerves was measured simultaneously using three buckle force transducers during seven upper limb positions in the axilla of ten embalmed whole body human cadavers (n = 20 limbs). Repeated measures analysis of variance (ANOVA) with Bonferroni post-hoc tests determined differences in tension between nerves and between limb positions. A Composite position consisting of ULNT2b (scapular depression, shoulder internal rotation, elbow extension, forearm pronation, wrist flexion) with the addition of shoulder abduction 40° and extension 25°, wrist ulnar deviation and thumb flexion demonstrated significantly greater tension of the radial nerve than any other tested position (mean tension 11.32N; 95% CI 10.25, 12.29, p < 0.01), including ULNT2b (2.20N; 1.84, 2.57; p < 0.01). Additionally, the Composite position demonstrated the greatest difference in tension between the radial and median (mean difference 4.88N; 95% CI 3.16, 6.61; p < 0.01) and radial and ulnar nerves (9.26N, 7.54, 10.99; p < 0.01). This position constitutes a biomechanically plausible test to detect neuropathic pain related to the radial nerve. PMID:25892706

  5. Improving the radial nerve neurodynamic test: An observation of tension of the radial, median and ulnar nerves during upper limb positioning.

    PubMed

    Manvell, Joshua J; Manvell, Nicole; Snodgrass, Suzanne J; Reid, Susan A

    2015-12-01

    The radial nerve neurodynamic test (ULNT2b), used to implicate symptoms arising from the radial nerve, is proposed to selectively increase strain of the nerve without increasing strain of adjacent tissue, though this has not been established. This study aimed to determine the upper limb position that results in: (1) the greatest tension of the radial nerve and (2) the greatest difference in tension between the radial nerve and the other two major nerves of the upper limb: median and ulnar. Tension (N) of the radial, median and ulnar nerves was measured simultaneously using three buckle force transducers during seven upper limb positions in the axilla of ten embalmed whole body human cadavers (n = 20 limbs). Repeated measures analysis of variance (ANOVA) with Bonferroni post-hoc tests determined differences in tension between nerves and between limb positions. A Composite position consisting of ULNT2b (scapular depression, shoulder internal rotation, elbow extension, forearm pronation, wrist flexion) with the addition of shoulder abduction 40° and extension 25°, wrist ulnar deviation and thumb flexion demonstrated significantly greater tension of the radial nerve than any other tested position (mean tension 11.32N; 95% CI 10.25, 12.29, p < 0.01), including ULNT2b (2.20N; 1.84, 2.57; p < 0.01). Additionally, the Composite position demonstrated the greatest difference in tension between the radial and median (mean difference 4.88N; 95% CI 3.16, 6.61; p < 0.01) and radial and ulnar nerves (9.26N, 7.54, 10.99; p < 0.01). This position constitutes a biomechanically plausible test to detect neuropathic pain related to the radial nerve.

  6. Coevolution of radial glial cells and the cerebral cortex

    PubMed Central

    De Juan Romero, Camino

    2015-01-01

    Abstract Radial glia cells play fundamental roles in the development of the cerebral cortex, acting both as the primary stem and progenitor cells, as well as the guides for neuronal migration and lamination. These critical functions of radial glia cells in cortical development have been discovered mostly during the last 15 years and, more recently, seminal studies have demonstrated the existence of a remarkable diversity of additional cortical progenitor cell types, including a variety of basal radial glia cells with key roles in cortical expansion and folding, both in ontogeny and phylogeny. In this review, we summarize the main cellular and molecular mechanisms known to be involved in cerebral cortex development in mouse, as the currently preferred animal model, and then compare these with known mechanisms in other vertebrates, both mammal and nonmammal, including human. This allows us to present a global picture of how radial glia cells and the cerebral cortex seem to have coevolved, from reptiles to primates, leading to the remarkable diversity of vertebrate cortical phenotypes. GLIA 2015;63:1303–1319 PMID:25808466

  7. Trajectory correction for free-breathing radial cine MRI.

    PubMed

    Buonincontri, Guido; Methner, Carmen; Krieg, Thomas; Carpenter, T Adrian; Sawiak, Stephen J

    2014-09-01

    Radial acquisitions can suffer from trajectory errors leading to reduced image quality. Here we present a new method of trajectory correction that uses all spokes of a radial acquisition and compare it to an existing method that uses a two-spoke pre-scan calibration. For both methods, estimates of the necessary shifts were made using magnitude or phase data and the performances were compared. The additional effect of B0 correction was considered in all cases. Mouse cardiac scans were used for the comparisons and we also compared the quality of navigator signals obtained from the radial data with each technique. The proposed method gave improved image quality over the existing method, as assessed by visual inspection and quantitative evaluation of artifacts. The typical shading artifacts seen in radial scans were significantly reduced with both approaches, with phase-based corrections generally outperforming magnitude-based methods. B0 correction gave further improvements in each case. Furthermore, modulation of navigator signals due to the acquisition angle was significantly reduced with the new technique. We show that our proposed method works well to reduce artifacts seen in mouse cardiac imaging that can make faster imaging feasible. PMID:24848290

  8. Angular velocity discrimination

    NASA Technical Reports Server (NTRS)

    Kaiser, Mary K.

    1990-01-01

    Three experiments designed to investigate the ability of naive observers to discriminate rotational velocities of two simultaneously viewed objects are described. Rotations are constrained to occur about the x and y axes, resulting in linear two-dimensional image trajectories. The results indicate that observers can discriminate angular velocities with a competence near that for linear velocities. However, perceived angular rate is influenced by structural aspects of the stimuli.

  9. Fiber Optic Velocity Interferometry

    SciTech Connect

    Neyer, Barry T.

    1988-04-01

    This paper explores the use of a new velocity measurement technique that has several advantages over existing techniques. It uses an optical fiber to carry coherent light to and from a moving target. A Fabry-Perot interferometer, formed by a gradient index lens and the moving target, produces fringes with a frequency proportional to the target velocity. This technique can measure velocities up to 10 km/s, is accurate, portable, and completely noninvasive.

  10. Lithosphere-Asthenosphere Transition, Mid-Lithosphere Discontinuity and Radial Anisotropy from Multi-mode Surface Wave Tomography

    NASA Astrophysics Data System (ADS)

    Yoshizawa, K.; Kennett, B. L. N.

    2015-12-01

    Seismic surface waves are the major source of information to delineate the lateral heterogeneity and anisotropy in the upper mantle. S-wave radial anisotropy representing the difference between SV and SH velocities is often discussed with the seismic properties of the lithosphere-asthenosphere transition (LAT) and the mid-lithosphere discontinuity (MLD). Such boundaries have been studied well by body-wave receiver functions, which have a good sensitivity to the sharpness of boundaries. Surface waves are rather insensitive to the boundary sharpness, but can delineate the spatial distributions of shear wave speeds and radial anisotropy in the upper mantle, which can be alternative constraints on LAT and MLD. We have recently constructed a radially anisotropic 3-D S wave speed model of the Australian continent from multi-mode Love and Rayleigh waves with enhanced ray coverage. In the inversions for S-wave radial anisotropy, we can use either parameterizations for SH and SV velocities, or for dimensionless radially anisotropic parameter ξ=(Vsh/Vsv)2. Both are theoretically the same, but this difference causes non-negligible effects on the estimated radial anisotropy, mainly due to the different sensitivities of Love-wave phase speeds to the structural parameters. Synthetic experiments and data variance reductions suggest the former is the better choice. The LAT throughout the continent can be estimated by the vertical velocity gradient of the isotropic S-wave model. The radial anisotropy with the suitable model parameterization shows strong anisotropy with faster SH velocity in the asthenosphere, suggesting the influence of strong shear beneath the fast drifting Australian continent. We can also identify the clear vertical changes in the radial anisotropy profiles at the MLD depth estimated from earlier receiver function studies in cratonic regions, which can be a key to elucidate the enigmatic MLD in the continental lithosphere.

  11. Effects of basilar membrane arch and radial tension on the travelling wave in gerbil cochlea.

    PubMed

    Chan, Wei Xuan; Yoon, Yong-Jin

    2015-09-01

    The basilar membrane velocity of gerbil cochlea showed discrepancy between theoretical model and experimental measurements. We hypothesize that the reasons of such discrepancies are due to the arch towards the scala tympani and radial tension present in the basilar membrane of the gerbil cochlea. The arch changes the bending stiffness in the basilar membrane, reduces the effective fluid force on the membrane and increases the basilar membrane's inertia. The existence of the radial tension also dampens the acoustic travelling wave. In this paper, the wave number functions along the gerbil basilar membrane are calculated from experimentally measured physical parameters with the theoretical model as well as extracted from experimentally measured basilar membrane velocity with the wave number inversion formula. The two wave number functions are compared and the effects of the tension and membrane arch on the wave number are studied based on various parameters of the model. We found that the bending stiffness across the gerbil basilar membrane varies (1-2 orders along the cochlea in the section 2.2 mm-3 mm from base) more than the calculated value in the flat basilar membrane model and the radial tension increases the damping of the travelling wave in gerbil cochlea significantly (5 times more than that without radial tension). These effects of arch and radial tension in the basilar membrane elucidate the discrepancy between previous theoretical model and experimental measurements in gerbil cochlea.

  12. Correlation between longitudinal, circumferential, and radial moduli in cortical bone: effect of mineral content.

    PubMed

    Macione, J; Depaula, C A; Guzelsu, N; Kotha, S P

    2010-07-01

    Previous studies indicate that changes in the longitudinal elastic properties of bone due to changes in mineral content are related to the longitudinal strength of bone tissue. Changes in mineral content are expected to affect bone tissue mechanical properties along all directions, albeit to different extents. However, changes in tissue mechanical properties along the different directions are expected to be correlated to one another. In this study, we investigate if radial, circumferential, and longitudinal moduli are related in bone tissue with varying mineral content. Plexiform bovine femoral bone samples were treated in fluoride ion solutions for a period of 3 and 12 days to obtain bones with 20% and 32% lower effective mineral contents. Transmission ultrasound velocities were obtained in the radial, circumferential, and longitudinal axes of bone and combined with measured densities to obtain corresponding tensorial moduli. Results indicate that moduli decreased with fluoride ion treatments and were significantly correlated to one another (r(2) radial vs. longitudinal = 0.80, r(2) circumferential vs. longitudinal = 0.90, r(2) radial vs. circumferential = 0.85). Densities calculated from using ultrasound parameters, acoustic impedance and transmission velocities, were moderately correlated to those measured by the Archimedes principle (r(2)=0.54, p<0.01). These results suggest that radial