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Sample records for absolute proper motion

  1. SPM4: The Yale/San-Juan Southern Proper Motion Survey: 100 million absolute proper motions

    NASA Astrophysics Data System (ADS)

    van Altena, W. F.

    2011-10-01

    The Yale/San Juan Southern Proper Motion SPM4 Catalog is the culmination of a highly successful 47-year collaboration between the National University of San Juan (UNSJ) and the Yale Southern Observatory (YSO). The SPM4 Catalog contains absolute proper motions, celestial coordinates, blue and visual passband photometry for 103 million stars and galaxies between the south celestial pole and δ=-20°. The Catalog is roughly complete to V = 17.5 and the precision of its positions and absolute proper motions is approximately 30 to 150 mas and 2 to 10 mas yr^{-1}, respectively.

  2. SPM4: The Yale/San-Juan Southern Proper Motion survey: 100 million absolute proper motions

    NASA Astrophysics Data System (ADS)

    van Altena, W. F.; Girard, T. M.; Casetti, D. I.; Vieira, K.; López, C. E.; Castillo, D.; Monet, D.; Zacharias, N.; Korchagin, V. I.; Platais, I.; Lee, Y. S.; Beers, T. C.; Herrera, D.

    The Yale/San Juan Southern Proper Motion SPM4 Catalog is the culmi- nation of a highly successful 47-year collaboration between the National University of San Juan (UNSJ) and the Yale Southern Observatory (YSO). The SPM4 Catalog contains absolute proper motions, celestial coordinates, blue and visual passband photometry for 103,319,647 stars and galaxies be- tween the south celestial pole and -20 degrees declination. The Catalog is roughly complete to V=17.5 and the precision of its positions and absolute proper motions is approximately 30 to 150 mas and 2 to 10 mas/yr, respec- tively. It is based on photographic and CCD observations taken with the Yale Southern Observatory's double-astrograph at the Cesco Observatory in El Leoncito, Argentina.

  3. Absolute Proper Motions of Nearby Dwarf Spheroidal Galaxies

    NASA Astrophysics Data System (ADS)

    Olszewski, Edward

    1997-07-01

    We propose to measure precise absolute proper motions for four dwarf spheroidal satellites of the Milky Way using spectroscopically-confirmed background QSOs to define a zero- velocity reference frame. Two epochs separated by 2 yrs will yield systemic tangential velocities of UMi, Car, Scl, {and For} to +/- 78 kms {+/- 130 kms}. These are worst-case velocity precisions and they are likely to be 2-4* smaller. Our long-term goal is to reduce them by an additional factor of several by obtaining data over the lifetime of WFPC2. With 2-3 QSOs per galaxy, we will still be confident of our motions with only 2 epochs. We will test whether the halo contains a small number of massive streams containing several dwarf galaxies, or whether the individual halo dwarfs are traveling along independent orbits. HST is essential to achieving the high precisions needed to conclusively compare the projected orbital motions of the individual galaxies; even with our conservative uncertainties, we are competitive with the best ground-based efforts with only a 2 year baseline. We will also use our results to improve our estimate of the mass of the Galaxy interior to 100 kpc. We believe that our project will show that astrometry has been a much ignored resource and power of HST. If HST performs as well as we suspect it can, it will be possible to measure the internal motions of stars in the dwarf spheroidals and the proper motions of all of the Local Group members over a timespan of 5 - 10 years.

  4. Absolute parallaxes and proper motions from the PARSEC program

    NASA Astrophysics Data System (ADS)

    2011-10-01

    The PARallaxes of Southern Extremely Cool objects (PARSEC) program is designed to measure trigonometric parallaxes of 150 confirmed brown dwarfs in the southern hemisphere with the aim of using distances as fundamental calibrators for the investigation of star formation and evolution in the very low-mass regime. A scientifically useful addition to the primary scope of the project is the derivation of stellar proper motions, by combining observations from the full field of view, linked to the UCAC2 catalogue, with first-epoch data from 2MASS. To date, a proper motion catalogue of about 200 000 objects has been compiled. Tailored reduction techniques allow to attain milliarcsecond accuracy in the derived astrometric parameters, as validated by external comparisons.

  5. VizieR Online Data Catalog: Absolute Proper motions Outside the Plane (APOP) (Qi+, 2015)

    NASA Astrophysics Data System (ADS)

    Qi, Z. X.; Yu, Y.; Bucciasrelli, B.; Lattanzi, M. G.; Smart, R. L.; Spagna, A.; McLean, B. J.; Tang, Z. H.; Jones, H. R. A.; Morbidelli, R.; Nicastro, L.; Vacchiato, A.

    2015-09-01

    The APOP is a absolute proper motion catalog achieved on the Digitized Sky Survey Schmidt plates data established by GSC-II project that outside the galactic plane (|b|>27°). The sky cover of this catalog is 22,525 square degree, the mean density is 4473 objects/sq.deg. and the magnitude limit is around R=20.8mag. The systematic errors of absolute proper motions related to the position, magnitude and color are practically all removed by using the extragalactic objects. The zero point error of absolute proper motions is less than 0.6mas/yr, and the accuracy is better than 4.0mas/yr for objects bright than R=18.5, and rises to 9.0mas/yr for objects with magnitude 18.5-30 degree and is not very well for others, the reason is that the epoch difference is large for Declination>-30° (45 years) but South than that is only around 12 years. It is fine for statistical studies for objects with Declination<-30° that people could find and remove obviously incorrect entries. (1 data file).

  6. An Absolute Proper motions and position catalog in the galaxy halos

    NASA Astrophysics Data System (ADS)

    Qi, Zhaoxiang

    2015-08-01

    We present a new catalog of absolute proper motions and updated positions derived from the same Space Telescope Science Institute digitized Schmidt survey plates utilized for the construction of the Guide Star Catalog II. As special attention was devoted to the absolutization process and removal of position, magnitude and color dependent systematic errors through the use of both stars and galaxies, this release is solely based on plate data outside the galactic plane, i.e. |b| ≥ 27o. The resulting global zero point error is less than 0.6 mas/yr, and the precision better than 4.0 mas/yr for objects brighter than RF = 18.5, rising to 9.0 mas/yr for objects with magnitude in the range 18.5 < RF < 20.0. The catalog covers 22,525 square degrees and lists 100,777,385 objects to the limiting magnitude of RF ˜ 20.8. Alignment with the International Celestial Reference System (ICRS) was made using 1288 objects common to the second realization of the International Celestial Reference Frame (ICRF2) at radio wavelengths. As a result, the coordinate axes realized by our astrometric data are believed to be aligned with the extragalactic radio frame to within ±0.2 mas at the reference epoch J2000.0. This makes our compilation one of the deepest and densest ICRF-registered astrometric catalogs outside the galactic plane. Although the Gaia mission is poised to set the new standard in catalog astronomy and will in many ways supersede this catalog, the methods and procedures reported here will prove useful to remove astrometric magnitude- and color-dependent systematic errors from the next generation of ground-based surveys reaching significantly deeper than the Gaia catalog.

  7. A Brief Overview of the Absolute Proper motions Outside the Plane catalog (APOP)

    NASA Astrophysics Data System (ADS)

    Qi, Zhaoxiang; Yu, Yong; Smart, Richard L.; Lattanzi, Mario G.; Bucciarelli, Beatrice; Spagna, Alessandro; McLean, Brian J.; Tang, Zhenghong; Jones, Hugh R. A.; Morbidelli, Roberto; Nicastro, Luciano; Vecchiato, Alberto; Teixeira, Ramachrisna

    2015-10-01

    APOP is the first version of an absolute proper motion catalog achieved using the Digitized Sky Survey Schmidt plate material outside the galactic plane (|b|≥ 27(o) ). The resulting global zero point error is less than 0.6 mas/yr, and the precision better than 4.0 mas/yr for objects brighter than R_{F}=18.5, rising to 9.0 mas/yr for objects with magnitude in the range 18.5

  8. Hubble space telescope absolute proper motions of NGC 6681 (M70) and the sagittarius dwarf spheroidal galaxy

    SciTech Connect

    Massari, D.; Ferraro, F. R.; Dalessandro, E.; Lanzoni, B.

    2013-12-10

    We have measured absolute proper motions for the three populations intercepted in the direction of the Galactic globular cluster NGC 6681: the cluster itself, the Sagittarius dwarf spheroidal galaxy, and the field. For this, we used Hubble Space Telescope ACS/WFC and WFC3/UVIS optical imaging data separated by a temporal baseline of 5.464 yr. Five background galaxies were used to determine the zero point of the absolute-motion reference frame. The resulting absolute proper motion of NGC 6681 is (μ{sub α}cos δ, μ{sub δ}) = (1.58 ± 0.18, –4.57 ± 0.16) mas yr{sup –1}. This is the first estimate ever made for this cluster. For the Sgr dSph we obtain (μ{sub α}cos δ, μ{sub δ}) = –2.54 ± 0.18, –1.19 ± 0.16) mas yr{sup –1}, consistent with previous measurements and with the values predicted by theoretical models. The absolute proper motion of the Galaxy population in our field of view is (μ{sub α}cos δ, μ{sub δ}) = (– 1.21 ± 0.27, –4.39 ± 0.26) mas yr{sup –1}. In this study we also use background Sagittarius Dwarf Spheroidal stars to determine the rotation of the globular cluster in the plane of the sky and find that NGC 6681 is not rotating significantly: v {sub rot} = 0.82 ± 1.02 km s{sup –1} at a distance of 1' from the cluster center.

  9. Absolute Proper Motions Outside the Plane (APOP)&mdashA Step Toward the GSC2.4

    NASA Astrophysics Data System (ADS)

    Qi, Zhaoxiang; Yu, Yong; Bucciarelli, Beatrice; Lattanzi, Mario G.; Smart, Richard L.; Spagna, Alessandro; McLean, Brian J.; Tang, Zhenghong; Jones, Hugh R. A.; Morbidelli, Roberto; Nicastro, Luciano; Vecchiato, Alberto

    2015-10-01

    We present a new catalog of absolute proper motions and updated positions derived from the same Space Telescope Science Institute digitized Schmidt survey plates utilized for the construction of Guide Star Catalog II. As special attention was devoted to the absolutization process and the removal of position, magnitude, and color dependent systematic errors through the use of both stars and galaxies, this release is solely based on plate data outside the galactic plane, i.e., | b| ≥slant 27^\\circ . The resulting global zero point error is less than 0.6 mas yr-1, and the precision is better than 4.0 mas yr-1 for objects brighter than RF = 18.5, rising to 9.0 mas yr-1 for objects with magnitudes in the range 18.5 < RF < 20.0. The catalog covers 22,525 square degrees and lists 100,774,153 objects to the limiting magnitude of RF ˜ 20.8. Alignment with the International Celestial Reference System was made using 1288 objects common to the second realization of the International Celestial Reference Frame (ICRF2) at radio wavelengths. As a result, the coordinate axes realized by our astrometric data are believed to be aligned with the extragalactic radio frame to within ±0.2 mas at the reference epoch J2000.0. This makes our compilation one of the deepest and densest ICRF-registered astrometric catalogs outside the galactic plane. Although the Gaia mission is poised to set the new standard in catalog astronomy and will in many ways supersede this catalog, the methods and procedures reported here will prove useful to remove astrometric magnitude- and color-dependent systematic errors from the next generation of ground-based surveys reaching significantly deeper than the Gaia catalog.

  10. PROMOTIONS: PROper MOTION Software

    NASA Astrophysics Data System (ADS)

    Caleb Wherry, John; Sahai, R.

    2009-05-01

    We report on the development of a software tool (PROMOTIONS) to streamline the process of measuring proper motions of material in expanding nebulae. Our tool makes use of IDL's widget programming capabilities to design a unique GUI that is used to compare images of the objects from two epochs. The software allows us to first orient and register the images to a common frame of reference and pixel scale, using field stars in each of the images. We then cross-correlate specific morphological features in order to determine their proper motions, which consist of the proper motion of the nebula as a whole (PM-neb), and expansion motions of the features relative to the center. If the central star is not visible (quite common in bipolar nebulae with dense dusty waists), point-symmetric expansion is assumed and we use the average motion of high-quality symmetric pairs of features on opposite sides of the nebular center to compute PM-neb. This is then subtracted out to determine the individual movements of these and additional features relative to the nebular center. PROMOTIONS should find wide applicability in measuring proper motions in astrophysical objects such as the expanding outflows/jets commonly seen around young and dying stars. We present first results from using PROMOTIONS to successfully measure proper motions in several pre-planetary nebulae (transition objects between the red giant and planetary nebula phases), using images taken 7-10 years apart with the WFPC2 and ACS instruments on board HST. The authors are grateful to NASA's Undergradute Scholars Research Program (USRP) for supporting this research.

  11. Absolute proper motions to B approximately 22.5: Evidence for kimematical substructure in halo field stars

    NASA Technical Reports Server (NTRS)

    Majewski, Steven R.; Munn, Jeffrey A.; Hawley, Suzanne L.

    1994-01-01

    Radial velocities have been obtained for six of nine stars identified on the basis of similar distances and common, extreme transverse velocities in the proper motion survey of Majewski (1992) as a candidate halo moving group at the north Galactic pole. These radial velocities correspond to velocities perpendicular to the Galactic plane which span the range -48 +/- 21 to -128 +/- 9 km/sec (but a smaller range, -48 +/- 21 to -86 +/- 19 km/sec, when only our own measurements are considered), significantly different than the expected distribution, with mean 0 km/sec, for a random sample of either halo or thick disk stars. The probability of picking such a set of radial velocities at random is less than 1%. Thus the radial velocity data support the hypothesis that these stars constitute part of a halo moving group or star stream at a distance of approximately 4-5 kpc above the Galactic plane. If real, this moving group is evidence for halo phase space substructure which may be the fossil remains of a destroyed globular cluster, Galactic satellite, or Searle & Zinn (1978) 'fragment.'

  12. Absolute Proper Motions to B~22.5. IV. Faint, Low-Velocity White Dwarfs and the White Dwarf Population Density Law

    NASA Astrophysics Data System (ADS)

    Majewski, S. R.; Siegel, M. H.

    2002-04-01

    The reduced proper-motion diagram (RPMD) for a complete sample of 819 faint (B<=22.5) stars with high-accuracy proper motions (σμ~1 mas yr-1) in an area of 0.3 deg2 in the north Galactic pole field SA 57 is investigated. Eight stars with very large reduced proper motions are identified as faint white dwarf candidates. On the basis of larger than 6 σ measured proper motions and the lack of photometric variability over a 20 yr baseline, we discriminate these white dwarf candidates from the several times more numerous quasi-stellar objects (QSOs), which can potentially occupy a similar location in the RPMD. For comparison, less than 4 σ proper motions and photometric variability are found in all but one of 35 spectroscopically confirmed QSOs in the same field. While spectroscopic confirmation of their status as white dwarfs is a necessary, but difficult, outstanding task, we discuss the implausibility that these stars could be any kind of survey contaminant. High-quality proper motions lend confidence in our ability to separate white dwarfs from subdwarfs in the RPMD. If bona fide white dwarfs, the eight candidates found here represent a portion of the white dwarf population that hitherto has remained uninvestigated by previous surveys by virtue of the faint magnitudes and low proper motions of the stars. This faint, low-velocity sample represents an increase in the white dwarf sky surface density to B=22.5 by an order of magnitude than that found in the previously most complete surveys to this depth. However, because the majority of the stars discovered here are at projected distances of more than a disk scale height above the Galactic midplane, their existence does not affect significantly the typical estimates of the local white dwarf density. On the other hand, as distant white dwarf candidates with low, typically thin-disk-like transverse velocities (<40 km s-1), the newly discovered stars suggest a disk white dwarf scale height larger than the values of 250

  13. Cool White Dwarfs Selection with Pan-STARRS Proper Motions

    NASA Astrophysics Data System (ADS)

    Lam, M. C.; Hambly, N. C.

    2015-06-01

    The use of Reduced Proper Motion in identifying isolated white dwarfs has long been used as a proxy for the absolute magnitude in a population with known kinematics. This, however, introduces a proper motion detection limit on top of the existing photometric limit. How the survey volume is hampered by this extra parameter is discussed in Hambly et al (2012). In this work, we discuss some robust outlier rejection methods in order to minimise the proper motion limit and hence maximise the survey volume. The generalised volume, corrected for the distance of the Sun from the Galactic Plane, is integrated explicitly.

  14. The Proper Motion of Palomar 5

    NASA Astrophysics Data System (ADS)

    Fritz, T. K.; Kallivayalil, N.

    2015-10-01

    Palomar 5 (Pal 5) is a faint halo globular cluster associated with narrow tidal tails. It is a useful system to understand the process of tidal dissolution, as well as to constrain the potential of the Milky Way. A well-determined orbit for Pal 5 would enable detailed study of these open questions. We present here the first CCD-based proper motion measurement of Pal 5 obtained using SDSS as a first epoch and new Large Binocular Telescope/Large Binocular Camera (LBC) images as a second, giving a baseline of 15 years. We perform relative astrometry, using SDSS as a distortion-free reference, and images of the cluster and also of the Pal 5 stream for the derivation of the distortion correction for LBC. The reference frame is made up of background galaxies. We correct for differential chromatic refraction using relations obtained from SDSS colors as well as from flux-calibrated spectra, finding that the correction relations for stars and for galaxies are different. We obtain μα = -2.296 ± 0.186 mas yr-1 and μδ = -2.257 ± 0.181 mas yr-1 for the proper motion of Pal 5. We use this motion, and the publicly available code galpy, to model the disruption of Pal 5 in different Milky Way models consisting of a bulge, a disk, and a spherical dark matter halo. Our fits to the observed stream properties (streak and radial velocity gradient) result in a preference for a relatively large Pal 5 distance of around 24 kpc. A slightly larger absolute proper motion than what we measure also results in better matches but the best solutions need a change in distance. We find that a spherical Milky Way model, with V0 = 220 km s-1 and V20 kpc, i.e., approximately at the apocenter of Pal 5, of 218 km s-1, can match the data well, at least for our choice of disk and bulge parametrization. Based on LBT data. The LBT is an international collaboration among institutions in the United States, Italy and Germany. LBT Corporation partners are: The Ohio State University, and The Research

  15. UrHip Proper Motion Catalog

    NASA Astrophysics Data System (ADS)

    Frouard, J.; Dorland, B. N.; Makarov, V. V.; Zacharias, N.; Finch, C. T.

    2015-11-01

    Proper motions are computed and collected in a catalog using the Hipparcos positions (epoch 1991.25) and URAT1 positions (epoch 2012.3-2014.6). The goal is to obtain a significant improvement on the proper motion accuracy of single stars in the northern hemisphere, and to identify new astrometric binaries perturbed by orbital motion. For binaries and multiple systems, the longer baseline of Tycho2 (˜100 years) makes it more reliable despite its larger formal uncertainties. The resulting proper motions obtained for 67,340 stars have a consequent gain in accuracy by a factor of ˜3 compared to Hipparcos. Comparison between UrHip and Hipparcos shows that they are reasonably close, but also reveals stars with large discrepant proper motions, a fraction of which are potential binary candidates.

  16. Proper Motion of the Magellanic Clouds using SPM

    NASA Astrophysics Data System (ADS)

    Vieira, K.; Girard, T.; van Altena, W.; Zacharias, N.; Casetti, D.; Korchagin, V.; Platais, I.; Monet, D.; López, C.

    2014-06-01

    Absolute proper motions are determined for stars and galaxies to V = 17.5 over a 450 square-degree area that includes the Magellanic Clouds, using photographic and CCD observations of the Yale/San Juan Southern Proper Motion program. Multiple, local relative proper motion measures were combined in an overlap solution using photometrically selected galactic disk stars to define a global relative system that is then transformed to absolute using external galaxies and Hipparcos stars to tie into the ICRS. The resulting catalog is used to derive the mean absolute proper motions of the Magellanic Clouds: (μ_{α}^{} cos δ, μ_{δ}^{})_LMC=(+1.88, +0.37)±(0.27, 0.27) mas yr^-1 and (μ_{α}^{} cos δ, μ_{δ}^{})_SMC=(+1.05, -1.03)±(0.30, 0.29) mas yr^-1, based on best-measured samples of 3822 LMC stars and 964 SMC stars. A dominant portion of the formal errors is due to the estimated uncertainty in the inertial system of the Hipparcos Catalog. A more precise determination was made for the proper motion of the SMC relative to the LMC; (μ_{{α cos δ }}^{}, μ_{δ}^{})_{SMC-LMC}=(-0.91, -1.49)±(0.16, 0.15) mas yr^-1. This differential value is used to estimate of the total velocity difference of the two clouds to within ±54 km s^-1. The absolute proper motion results are consistent with the Clouds' orbits being marginally bound to the Milky Way, albeit on an elongated orbit.

  17. INTERNAL PROPER MOTIONS IN THE ESKIMO NEBULA

    SciTech Connect

    García-Díaz, Ma. T.; Gutiérrez, L.; Steffen, W.; López, J. A.; Beckman, J. E-mail: leonel@astro.unam.mx E-mail: jal@astro.unam.mx

    2015-01-10

    We present measurements of internal proper motions at more than 500 positions of NGC 2392, the Eskimo Nebula, based on images acquired with WFPC2 on board the Hubble Space Telescope at two epochs separated by 7.695 yr. Comparisons of the two observations clearly show the expansion of the nebula. We measured the amplitude and direction of the motion of local structures in the nebula by determining their relative shift during that interval. In order to assess the potential uncertainties in the determination of proper motions in this object, in general, the measurements were performed using two different methods, used previously in the literature. We compare the results from the two methods, and to perform the scientific analysis of the results we choose one, the cross-correlation method, because it is more reliable. We go on to perform a ''criss-cross'' mapping analysis on the proper motion vectors, which helps in the interpretation of the velocity pattern. By combining our results of the proper motions with radial velocity measurements obtained from high resolution spectroscopic observations, and employing an existing 3D model, we estimate the distance to the nebula to be 1.3 kpc.

  18. New high-proper motion survey in the Southern sky

    NASA Astrophysics Data System (ADS)

    Scholz, R.-D.; Irwin, M.; Ibata, R.; Jahreiß, H.; Malkov, O. Yu.

    2000-01-01

    We present the discovery of about 100 new high-proper motion stars in the region between 0h and 7h in right ascension and -63deg and -32deg in declination, with proper motions between 0.3 and 1.0 arcsec/yr. In addition we have obtained improved coordinates and photographic photometry for another about 100 already known high-proper motion stars in the same region. In this study we have made use of APM measurements of UKST survey plates in 40 survey fields. Using all available information (position, proper motion, photographic R magnitude and B_J-R colour index), we draw some preliminary conclusions on the nature of the new high-proper motion stars, particularly of extreme cases. In addition, for some of the new high-proper motion stars we carried out low resolution optical spectroscopy with the 1.9m Radcliffe telescope of the South Africa Astronomical Observatory (SAAO). The faintest discovered proper motion stars are a common proper motion pair with mu = 0.5 arcsec/yr, R magnitudes of 19.7 and 20.9 and B_J magnitudes of 20.6 and 22.9, respectively. A first estimate of the absolute magnitude of this proper motion pair APMPM J0352-4127AB based on estimating the distance from the extant observational data, yields M_V=15.8 +/- 2.3 and M_V=18.1 +/- 2.3, respectively for the two components. We conclude that both components are likely to be extremely cool degenerate white dwarfs. The SAAO spectrum of the brighter component is a first confirmation of the cool white dwarf nature, although the signal-to-noise was very low. There are other cool white dwarfs among the stars for which SAAO spectra were obtained. The star with the largest proper motion among the newly detected proper motion stars (mu = 0.95 arcsec/yr and R = 15.8; B_J-R = 2.2) had a spectrum corresponding to a mid-M dwarf. For the extremely red (B_J-R > 2.6) and blue (B_J-R < 0.7) stars in our sample, our prior assumptions based on photometry and proper motion of late type M dwarf or normal white dwarf nature

  19. Proper Motion Of Emerging Active Regions

    NASA Astrophysics Data System (ADS)

    Tian, Lirong

    2009-05-01

    Observational and modeling results indicate that typically the leading magnetic field of bipolar active regions is often spatially more compact, while more dispersed and fragmented in following polarity. Tian & Alexander (2009, ApJ, 695) studied 15 emerging active regions and find that magnetic helicity flux injected into the corona by the leading polarity is generally several times larger than that injected by the following polarity. They argue that the asymmetry of the magnetic helicity should be responsible for the asymmetry of the magnetic morphology. This argument is supported by two resent model results that magnetic flux tubes with higher degree of twist (and therefor greater magnetic tension) have higher rates of emergence (Murray & Hood 2008, A&A, 479; Cheung et al. 2008, ApJ, 687). These results are consistent because the proper motion (related to the emergence) of the leading polarity was found to be faster than that of the following polarity (van Driel-Gesztelyi & Petrovay 1990, Solar Phys., 126). In this paper, we will reinvestigate the proper motion of leading and following polarities of the emerging active regions, and study possible relationship between the proper motion and magnetic helicity.

  20. Aberration in proper motions for Galactic stars

    NASA Astrophysics Data System (ADS)

    Liu, J.-C.; Xie, Y.; Zhu, Z.

    2014-12-01

    Accelerations of both the solar system barycenter (SSB) and stars in the MilkyWay cause a systematic observational effect on the stellar proper motions, which was first studied by J. Kovalevsky (2003). This paper intends to extend that work and aims to estimate the magnitude and significance of the aberration in proper motions of stars, especially in the region near the Galactic center (GC). We adopt two models for the Galactic rotation curve to evaluate the aberrational effect on the Galactic plane. We show that the effect of aberration in proper motions depends on the galactocentric distance of stars; it is dominated by the acceleration of stars in the central region of the Galaxy. Then we investigate the applicability of the theoretical expressions: if the orbital period of stars is only a fraction of the light time from the star to the SSB, the expression with approximation proposed by Kovalevsky is not appropriate. With a more suitable formulation, we found that the aberration has no effect on the determination of the stellar orbits on the celestial sphere. In the future this aberrational effect under consideration should be considered with high-accurate astrometry, particularly in constructing the Gaia celestial reference system realized by Galactic stars.

  1. VVV IR high proper motion stars

    NASA Astrophysics Data System (ADS)

    Kurtev, R.; Gromadzki, M.; Beamin, J. C.; Peña, K.; Folkes, S.; Ivanov, V. D.; Borissova, J.; Kuhn, M.; Villanueva, V.; Minniti, D.; Mendez, R.; Lucas, P.; Smith, L.; Pinfield, D.; Antonova, A.

    2015-10-01

    We used the VISTA Variables en Vía Láctea (VVV) survey to search for large proper motion (PM) objects in the zone of avoidance in the Milky Way bulge and southern Galactic disk. This survey is multi-epoch and already spans a period of more than four years, giving us an excellent opportunity for proper motion and parallax studies. We found around 1700 PM objects with PM>30 mas yr(-1) . The majority of them are early and mid M-dwarfs. There are also few later spectral type objects, as well as numerous new K- and G-dwarfs. 75 of the stars have PM>300 mas (-1) and 189 stars have PM>200 mas (-1) . There are only 42 previously known stars in the VVV area with proper motion PM>200 mas (-1) . We also found three dM+WD binaries and new members of the immediate solar vicinity of 25 pc. We generated a catalog which will be a complementary to the existing catalogs outside this zone.

  2. Investigating the Highest Proper Motion Stars

    NASA Astrophysics Data System (ADS)

    Jao, Wei-Chun; Henry, Todd; Subasavage, John; Bean, Jacob

    2002-02-01

    There currently are 601 stars (502 systems) with proper motion faster than 1 arcsec/year (hereafter, MOTION stars). Among these MOTION stars, there are 186 systems (37%) without complete VRI photometric information on a standard system. We propose to obtain VRI band photometry from both CTIO and KPNO in order to characterize these stars. 75% of MOTION stars are estimated to lie within 25 pc of the Sun. These results will allow us to understand the colors, temperatures and luminosities for these fast moving objects and provide a complete picture of this definitive sample. The complete characterization of this sample comprises the thesis project of PI Jao. By obtaining VRI photometry for the MOTION stars , we will be able to identify new nearby star candidates for our second generation parallax project, CTIOPI2, planned as part of the new small telescope consortium at CTIO. The frames taken can be used to evaluate appropriate setup frames for future astrometry series. We also expect to discover new companions in the photometry frames. These companions can be identified by (1) confirming common proper motion using DSS frames and/or (2) initiating deep photometric searches by combining the VRI data with JHK photometry of nearby sources in 2MASS. Both types of new companions will contribute to our growing database that is being used to investigate the stellar multiplicity rate. Finally, the VRI photometry will allow us to identify the less common subdwarfs, white dwarfs or close binaries, many of which will be added to the lists of new nearby stars that will be the targets for future space missions such as SIM and TPF.

  3. Measuring Proper Motion of Barnard's Star

    NASA Astrophysics Data System (ADS)

    Wiechmann, Katrina; Michalik, Tom

    2009-03-01

    Stars of the night sky are generally considered to be fixed points, not changing noticeably over generations of observations. While most stars seem to appear in the same place year after year, some change location noticeably, the best example being Barnard's Star. Barnard's star is closer to Earth than any other star except Proxima Centauri. It also appears to move across the sky faster than any other star. This change in apparent location is caused by the movements of our Solar System and the motion of the star in question, and is known as proper motion. Using the astrometric capabilities of the MIRA software along with precise positional information for reference stars from the Tycho satellite star catalogue, the position of Barnard's star is computed relative to the reference stars. We calibrate a series of images of Barnard's Star taken in the Randolph College Observatory between 2001 and 2008 in order to independently determine the coordinates of Barnard's Star, revealing how these change over time. By measuring changes in the celestial coordinates, Right Ascension and Declination, we determine the proper motion of Barnard's star and compare this measurement to the accepted value of 10.25'' per year.

  4. Discovery and characterization of the highest proper motion stars

    NASA Astrophysics Data System (ADS)

    Jao, Wei-Chun

    This dissertation presents methods and results of searching for missing stars in the solar neighborhood based on a rigorous selection of the highest proper motion stars. The MOTION sample of stars discussed in this work includes all systems with proper motions greater than [Special characters omitted.] /yr. As of January 1, 2003, there are 549 systems and 653 individual stars in the sample. We characterize all of these systems astrometrically, photometrically and spectroscopically. Data supporting this investigation have been taken as part of CTIOPI (Cerro Tololo Inter-American Observatory Parallax Investigation), for which data acquisition and reduction techniques are discussed. In addition to the production of trigonometric parallaxes, proper motions, and VRI photometry, atmospheric refraction is addressed in detail for the astrometric observations, and the photometry is used to convert the relative parallaxes to absolute parallaxes. We report first ever parallax measurements for 46 MOTION systems. Five of these are new RECONS (Research Consortium on Nearby Stars) systems within 10 pc of the Sun--LHS22, LHS145, LHS263, LHS337, and DENI1048-3956. An additional 25 systems are within the 25 pc NStars horizon. These parallax results cover more than 50% of the MOTION systems that previously had no trigonometric parallaxes. We also provide VRI photometry for 86 MOTION systems that previously had incomplete or no such photometry. Of these, 15 systems are photometrically estimated to be within 25 pc. In addition, we give new spectroscopy results for 43 MOTION systems. Because of the inherent kinematic bias in the sample, a full ~15% (82) of the MOTION systems prove to be subdwarfs, an important sample that will be useful for future investigations. In this sample we have identified the first M-type subdwarf binary, LHS189AB, and the first subdwarf/white dwarf binary, LHS193AB. Finally; nine new companions have been confirmed as proper motion companions to stars observed

  5. The physical properties of double degenerate common proper motion binaries

    NASA Technical Reports Server (NTRS)

    Sion, Edward M.; Oswalt, Terry D.; Liebert, James; Hintzen, Paul

    1991-01-01

    Spectral types and spectrophotometry are presented for 21 double degenerate (DD) common proper motion binaries, along with estimates of their colors, absolute visual and bolometric magnitudes, and cooling ages. The oldest pairs in the sample are 9 x 10 to the 9th yr; the differential cooling ages range from 0.01 to 0.84. The median and mean separations of the DD pairs are 426 and 407 Au, respectively, both apparently smaller than the WD+MS values. The average UVW motions and velocity dispersions are significantly larger than the average velocities and dispersions associated with selected samples of single white dwarfs and MS+WD binaries when the latter are restricted to the same color/Mv range as the DD systems. This may be a result of the dynamical inflation of the velocity dispersion of DD systems due to their extremely ancient total stellar ages.

  6. Cas A Dynamics: Doppler and Proper Motion

    NASA Astrophysics Data System (ADS)

    DeLaney, Tracey; Smith, J.; Rudnick, L.; Ennis, J.; Rho, J.; Reach, W.; Kozasa, T.; Gomez, H.

    2006-06-01

    We present Doppler velocity images of the young supernova remnant Cassiopeia A in the infrared emission lines of Ar, Ne, Si, and S observed with the Spitzer IRS and covering nearly the whole extent of the remnant. The measured infrared velocities of the shocked ejecta range from -4000 km/s to +6000 km/s. The Si and S emission near the center of the remnant, that is associated with ejecta that have not yet encountered the reverse shock, also shows both red- and blue-shifted structures with velocities between -3000 km/s and +3000 km/s. These unshocked ejecta provide a unique opportunity to study the kinematics of the explosion free from the influences of the reverse shock and CSM. The infrared kinematics are compared to optical and X-ray Doppler velocities and optical, X-ray, and radio proper motions. This work was performed for the Jet Propulsion Laboratory, California Institute of Technology, sponsored by the United States Government under Prime Contract between California Institute of Technology and NASA.

  7. A technique to derive improved proper motions for Kepler objects of interest

    SciTech Connect

    Benedict, G. Fritz; Tanner, Angelle M.; Cargile, Phillip A.; Ciardi, David R.

    2014-12-01

    We outline an approach yielding proper motions with higher precision than exists in present catalogs for a sample of stars in the Kepler field. To increase proper-motion precision, we combine first-moment centroids of Kepler pixel data from a single season with existing catalog positions and proper motions. We use this astrometry to produce improved reduced-proper-motion diagrams, analogous to a Hertzsprung-Russell (H-R) diagram, for stars identified as Kepler objects of interest. The more precise the relative proper motions, the better the discrimination between stellar luminosity classes. Using UCAC4 and PPMXL epoch 2000 positions (and proper motions from those catalogs as quasi-Bayesian priors), astrometry for a single test Channel (21) and Season (0) spanning 2 yr yields proper motions with an average per-coordinate proper-motion error of 1.0 mas yr{sup –1}, which is over a factor of three better than existing catalogs. We apply a mapping between a reduced-proper-motion diagram and an H-R diagram, both constructed using Hubble Space Telescope parallaxes and proper motions, to estimate Kepler object of interest K-band absolute magnitudes. The techniques discussed apply to any future small-field astrometry as well as to the rest of the Kepler field.

  8. Common Proper Motion Companions to Nearby Stars: Ages and Evolution

    NASA Astrophysics Data System (ADS)

    Makarov, V. V.; Zacharias, N.; Hennessy, G. S.

    2008-11-01

    A set of 41 nearby stars (closer than 25 pc) is investigated which have very wide binary and common proper motion (CPM) companions at projected separations between 1000 and 200,000 AU. These companions are identified by astrometric positions and proper motions from the NOMAD catalog. Based mainly on measures of chromospheric and X-ray activity, age estimation is obtained for most of 85 identified companions. Color-absolute magnitude diagrams are constructed to test whether CPM companions are physically related to the primary nearby stars and have the same age. Our carefully selected sample includes three remote white dwarf companions to main-sequence stars and two systems (55 Cnc and GJ 777A) of multiple planets and distant stellar companions. Ten new CPM companions, including three of extreme separations, are found. Multiple hierarchical systems are abundant; more than 25% of CPM components are spectroscopic or astrometric binaries or multiples themselves. Two new astrometric binaries are discovered among nearby CPM companions, GJ 264 and HIP 59000, and preliminary orbital solutions are presented. The Hyades kinematic group (or stream) is presented broadly in the sample, but we find few possible thick-disk objects and no halo stars. It follows from our investigation that moderately young (age lesssim 1 Gyr) thin-disk dwarfs are the dominating species in the near CPM systems, in general agreement with the premises of the dynamical survival paradigm.

  9. The Bonn contribution to the extragalactic link of the HIPPARCOS proper motion system.

    NASA Astrophysics Data System (ADS)

    Tucholke, H.-J.; Brosche, P.; Odenkirchen, M.

    1997-05-01

    In order to calibrate the proper motions of the Hipparcos astrometry satellite, our group has measured accurate absolute proper motions of Hipparcos stars in small fields around optically bright extragalactic radio sources or bright galaxies with star-like features. In addition, we also use fields where relative proper motions are calibrated by measurements of large numbers of stars and galaxies on wide-field plates. The median internal accuracy of our relative proper motions, based on photographic plates with epoch differences up to 100 years (typically 70 years), is 1.0 milliarcsec/year (mas/a), while the calibration to an inertial system in each of the 13 fields has a median uncertainty of 1.3 mas/a. We compute the rotation from the Hipparcos proper motions (median internal errors \\e{0.9}{mas/a}) to the extragalactic reference frame represented by our absolute proper motions, using 88 stars in common. The three components of the angular velocity vector have internal errors of 0.3 mas/a. Our rotation solution has been used together with those of independent groups for the extragalactic calibration of the Hipparcos proper motion system (\\cite[Kovalevsky et al. 1996)]{kova96}. It compares favourably with the adopted mean solution. Based on observations made with the ESA Hipparcos satellite.

  10. Proper motion survey with the forty-eight inch Schmidt telescope. 33: Proper motions for 3478 faint stars

    NASA Technical Reports Server (NTRS)

    Luyten, W. J.

    1972-01-01

    Data for the motions of 3478 stars are presented. The data were obtained with the automated-computerized plate scanner and measuring machine. Only data for those stars for which no earlier determination of proper motions are included.

  11. A digitized version of the NLTT Catalogue of proper motions

    NASA Technical Reports Server (NTRS)

    Warren, Wayne H., Jr.; Sturch, Conrad R.; Lasker, Barry M.; Jahreiss, Hartmut; Luyten, Willem J.

    1989-01-01

    An optically scanning data-entry machine and various manual techniques are used to digitize the NLTT Catalogue and the first supplement to the NLTT Catalogue. Included in the catalog are stars found on over 800 Palomar proper-motion survey plates to have relative annual proper motions exceeding 0.18 arcsec. The supplement contains data for 398 stars having motions larger than 0.179 arcsec annually.

  12. A 1500 deg2 near infrared proper motion catalogue from the UKIDSS Large Area Survey

    NASA Astrophysics Data System (ADS)

    Smith, Leigh; Lucas, P. W.; Burningham, B.; Jones, H. R. A.; Smart, R. L.; Andrei, A. H.; Catalán, S.; Pinfield, D. J.

    2014-02-01

    The United Kingdom Infrared Deep Sky Survey (UKIDSS) Large Area Survey (LAS) began in 2005, with the start of the UKIDSS programme as a 7 year effort to survey roughly 4000 deg2 at high Galactic latitudes in Y, J, H and K bands. The survey also included a significant quantity of two epoch J band observations, with an epoch baseline greater than 2 years to calculate proper motions. We present a near-infrared proper motion catalogue for the 1500 deg2 of the two epoch LAS data, which includes 135 625 stellar sources and a further 88 324 with ambiguous morphological classifications, all with motions detected above the 5σ level. We developed a custom proper motion pipeline which we describe here. Our catalogue agrees well with the proper motion data supplied for a 300 deg2 subset in the current Wide Field Camera Science Archive (WSA) 10th data release (DR10) catalogue, and in various optical catalogues, but it benefits from a larger matching radius and hence a larger upper proper motion detection limit. We provide absolute proper motions, using LAS galaxies for the relative to absolute correction. By using local second-order polynomial transformations, as opposed to linear transformations in the WSA, we correct better for any local distortions in the focal plane, not including the radial distortion that is removed by the UKIDSS pipeline. We present the results of proper motion searches for new brown dwarfs and white dwarfs. We discuss 41 sources in the WSA DR10 overlap with our catalogue with proper motions >300 mas yr-1, several of which are new detections. We present 15 new candidate ultracool dwarf binary systems.

  13. Corrections to erroneous proper motions of some AGK 3 stars

    NASA Astrophysics Data System (ADS)

    Lopez, Carlos E.

    1988-10-01

    Approximately 100 AGK 3 stars have such large published proper motions that they must be affected by spurious errors. For some of those stars south of +25 deg (20 in total), new proper motions have been determined by combining recent photographic positions with positions obtained from the rereduction of the published material of the Astrographic Catalogue. No attempt was made to include other positions than these. The new proper motions in the system of the AGK 3 are much smaller than the values quoted in said catalog.

  14. The Pan-STARRS 1 Parallax and Proper Motion Catalog

    NASA Astrophysics Data System (ADS)

    Waters, Christopher Z.; Magnier, Eugene A.; Pan-STARRS Science Consortium

    2016-01-01

    The Pan-STARRS 1 3-Pi survey produced a catalog of more than three billion objects north of -30 declination with astrometric precision down to 10 milliarcseconds per observation. This excellent calibration and the multiple observations of each point of the sky over a five year internal baseline allow proper motions as small as 1-2 mas/year to be measured. The observational schedule has been designed to optimize parallax measurements for red objects. The final parallax and proper motion catalog will enable searches for and classification of stars in the local solar neighborhood, with proper motion searches extending to 200 parsecs.

  15. Cataclysmic variables in the SUPERBLINK proper motion survey

    SciTech Connect

    Skinner, Julie N.; Thorstensen, John R.; Lépine, Sébastien

    2014-12-01

    We have discovered a new high proper motion cataclysmic variable (CV) in the SUPERBLINK proper motion survey, which is sensitive to stars with proper motions greater than 40 mas yr{sup −1}. This CV was selected for follow-up observations as part of a larger search for CVs selected based on proper motions and their near-UV−V and V−K{sub s} colors. We present spectroscopic observations from the 2.4 m Hiltner Telescope at MDM Observatory. The new CV's orbital period is near 96 minutes, its spectrum shows the double-peaked Balmer emission lines characteristic of quiescent dwarf novae, and its V magnitude is near 18.2. Additionally, we present a full list of known CVs in the SUPERBLINK catalog.

  16. A proper motion study of the globular cluster M55

    NASA Astrophysics Data System (ADS)

    Zloczewski, K.; Kaluzny, J.; Thompson, I. B.

    2011-07-01

    We have derived the absolute proper motion (PM) of the globular cluster M55 using a large set of CCD images collected with the du Pont telescope between 1997 and 2008. We find (μα cos δ, μδ) = (-3.31 ± 0.10, -9.14 ± 0.15) mas yr-1 relative to background galaxies. Membership status was determined for 16 945 stars with 14 < V < 21 from the central part of the cluster. The PM catalogue includes 52 variables, of which 43 are probable members of M55. This sample not only is dominated by pulsating blue straggler stars, but also includes five eclipsing binaries, three of which are main-sequence objects. The survey also identified several candidate blue, yellow and red straggler stars belonging to the cluster. We detected 15 likely members of the Sgr dSph galaxy located behind M55. The average PM for these stars was measured to be (μα cos δ, μδ) = (-2.23 ± 0.14, -1.83 ± 0.24) mas yr-1.

  17. Aberration in proper motions for stars in our Galaxy

    NASA Astrophysics Data System (ADS)

    Liu, J.-C.; Xie, Y.; Zhu, Z.

    2013-08-01

    Accelerations of both the Solar system barycentre (SSB) and stars in the Milky Way cause a systematic observational effect on the stellar proper motions, which was first studied in the early 1990s and developed by Kovalevsky (aberration in proper motions). This paper intends to extend that work and aims to estimate the magnitude and significance of the aberration in proper motions of stars, especially in the region near the Galactic Centre. We adopt two models for the Galactic rotation curve to evaluate the aberrational effect on the Galactic plane. Based on the theoretical developments, we show that the effect of aberration in proper motions depends on the Galactocentric distance of stars; it is dominated by the acceleration of stars in the central region of the Galaxy. Within 200 pc from the Galactic Centre, the systematic proper motion can reach an amplitude larger than 1000 μas yr- 1 by applying a flat rotation curve. With a more realistic rotation curve which is linearly rising in the core region of the Galaxy, the aberrational proper motions are limited up to about 150 μas yr- 1. Then we investigate the applicability of the theoretical expressions concerning the aberrational proper motions, especially for those stars with short period orbits. If the orbital period of stars is only a fraction of the light time from the star to the SSB, the expression proposed by Kovalevsky is not appropriate. With a more suitable formulation, we found that the aberration has no effect on the determination of the stellar orbits on the celestial sphere. The aberrational effect under consideration is small but not negligible with high-accurate astrometry in the future, particularly in constructing the Gaia celestial reference system realized by Galactic stars.

  18. The RECONS Effort to Characterize the Highest Proper Motion Stars

    NASA Astrophysics Data System (ADS)

    Jao, W. C.; Subasavage, J. P.; Henry, T. J.; Williams, C.; Costa, E.; Ianna, P. A.; Mendez, R. A.; RECONS Team

    2001-12-01

    High proper motion is a method used for selecting probable nearby stars. There currently are 601 stars (502 systems) with proper motion faster than 1 arcsec/year (hereafter, the MOTION stars). There are 271 systems known in the northern sky and 231 systems in the southern sky. The predominance of systems in the north is because historically more proper motion surveys have been carried out in northern hemisphere. In the complete MOTION sample, 75 estimated to lie within 25 pc of the Sun, the adopted horizon for NASA's NStars (Nearby Stars) Project. Based on available photometric and parallax observations, we know that MOTION members are primarily late type main sequence stars, with a few white dwarfs and subdwarfs. Nonetheless, it is remarkable that 16 not yet have parallax measurements. In addition, nearly 40 of the systems do not have complete VRI photometry on a standard system. In an effort to understand the complete MOTION sample, and to discover new members of the solar neighborhood, we present both astrometric and photometric results for the MOTION stars from our extensive NOAO Surveys Program known as CTIOPI (CTIO Parallax Investigation). The support of NOAO, CTIO, the NASA-Ames Astrobiology Institute and the NASA's Space Interferometry Mission have been the crucial to the success of this research.

  19. Proper Motion of Components in 4C 39.25

    NASA Technical Reports Server (NTRS)

    Guirado, J. C.; Marcaide, J. M.; Alberdi, A.; Elosegui, P.; Ratner, M. I.; Shapiro, I. I.; Kilger, R.; Mantovani, F.; Venturi, T.; Rius, A.; Ros, E.; Trigilio, C.; Whitney, A. R.

    1995-01-01

    From a series of simultaneous 8.4 and 2.3 GHz VLBI observations of the quasar 4C 39.25 phase referenced to the radio source 0920+390, carried out in 1990-1992, we have measured the proper motion of component b in 4C 39.25: mu(sub alpha) = 90 +/- 43 (mu)as/yr, mu(sub beta) = 7 +/- 68 (mu)as/yr, where the quoted uncertainties account for the contribution of the statistical standard deviation and the errors assumed for the parameters related to the geometry of the interferometric array, the atmosphere, and the source structure. This proper motion is consistent with earlier interpretations of VLBI hybrid mapping results, which showed an internal motion of this component with respect to other structural components. Our differential astrometry analyses show component b to be the one in motion. Our results thus further constrain models of this quasar.

  20. Δ μ binaries among stars with large proper motions

    NASA Astrophysics Data System (ADS)

    Khovritchev, M. Yu.; Kulikova, A. M.

    2015-12-01

    Based on observations performed with the Pulkovo normal astrograph in 2008-2015 and data from sky surveys (DSS, 2MASS, SDSS DR12, WISE), we have investigated the motions of 1308 stars with proper motions larger than 300 mas yr-1 down to magnitude 17. The main idea of our search for binary stars based on this material is reduced to comparing the quasi-mean (POSS2-POSS1; an epoch difference of ≈50 yr) and quasi-instantaneous (2МASS, SDSS, WISE, Pulkovo; an epoch difference of ≈10 yr) proper motions. If the difference is statistically significant compared to the proper motion errors, then the object may be considered as a Δ μ-binary candidate. One hundred and twenty one stars from among those included in the observational program satisfy this requirement. Additional confirmations of binarity for a number of stars have been obtained by comparing the calculated proper motions with the data from several programs of stellar trigonometric parallax determinations and by analyzing the asymmetry of stellar images on sky-survey CCD frames. Analysis of the highly accurate SDSS photometric data for four stars (J0656+3827, J0838+3940, J1229+5332, J2330+4639) allows us to reach a conclusion about the probability that these Δ μ binaries are white dwarf +Mdwarf pairs.

  1. Proper Motion of the Draco Dwarf Galaxy from Subaru Suprime-Cam Data

    NASA Astrophysics Data System (ADS)

    Casetti-Dinescu, Dana I.; Girard, Terrence M.

    2016-06-01

    We have measured the absolute proper motion of the Draco dwarf spheroidal galaxy using Subaru Suprime-Cam images taken at three epochs, with time baselines of 4.4 and 7 years. The magnitude limit of the proper-motion study is i = 25, thus allowing for thousands of background galaxies and Draco stars to be used to perform extensive astrometric tests and to derive the correction to an inertial reference frame. The derived proper motion is (μα, μδ) = ( - 0.284 ± 0.047, -0.289 ± 0.041) mas yr-1. This motion implies an orbit that takes Draco to a pericenter of ˜20 kpc; a somewhat disruptive orbit suggesting that tides might account for the rising velocity-dispersion profile of Draco seen in line-of-sight velocity studies. The orbit is only marginally consistent with Draco's membership to the vast polar structure of Galactic satellites, in contrast to a recent HST proper-motion measurement that finds alignment very likely. Our study is a test case to demonstrate that deep imaging with mosaic cameras of appropriate resolution can be used for high-accuracy, ground-based proper-motion measurement. As a useful by-product of the study, we also identify two faint brown-dwarf candidates in the foreground field.

  2. Proper motion of the Draco dwarf galaxy from Subaru Suprime-Cam data

    NASA Astrophysics Data System (ADS)

    Casetti-Dinescu, Dana I.; Girard, Terrence M.

    2016-09-01

    We have measured the absolute proper motion of the Draco dwarf spheroidal galaxy using Subaru Suprime-Cam images taken at three epochs, with time baselines of 4.4 and 7 yr. The magnitude limit of the proper-motion study is i = 25, thus allowing for thousands of background galaxies and Draco stars to be used to perform extensive astrometric tests and to derive the correction to an inertial reference frame. The derived proper motion is (μα, μδ) = (-0.284 ± 0.047, -0.289 ± 0.041) mas yr-1. This motion implies an orbit that takes Draco to a pericentre of ˜20 kpc; a somewhat disruptive orbit suggesting that tides might account for the rising velocity-dispersion profile of Draco seen in line-of-sight velocity studies. The orbit is only marginally consistent with Draco's membership to the vast polar structure of Galactic satellites, in contrast to a recent Hubble Space Telescope proper-motion measurement that finds alignment very likely. Our study is a test case to demonstrate that deep imaging with mosaic cameras of appropriate resolution can be used for high-accuracy, ground-based proper-motion measurement. As a useful by-product of the study, we also identify two faint brown-dwarf candidates in the foreground field.

  3. STELLAR PROPER MOTION AND THE TIMING OF PLANETARY TRANSITS

    SciTech Connect

    Rafikov, Roman R.

    2009-08-01

    Duration and period of transits in extrasolar planetary systems can exhibit long-term variations for a variety of reasons. Here we investigate how systemic proper motion, which steadily re-orients planetary orbit with respect to our line of sight, affects the timing of transits. We find that in a typical system with a period of several days, proper motion at the level of 100 mas yr{sup -1} makes transit duration vary at a rate {approx}10-100 ms yr{sup -1}. In some isolated systems this variation is at the measurable level (can be as high as 0.6 s yr{sup -1} for GJ436) and may exceed all other transit-timing contributions (due to the general relativity, stellar quadrupole, etc.). In addition, proper motion causes evolution of the observed period between transits P {sub obs} via the Shklovskii effect at a rate {approx}>10 {mu}s yr{sup -1} for the nearby transiting systems (0.26 ms yr{sup -1} in GJ436), which in some cases exceeds all other contributions to P-dot{sub obs}. Earth's motion around the Sun gives rise to additional periodic timing signal (even for systems with zero intrinsic proper motion) allowing a full determination of the spatial orientation of the planetary orbit. Unlike most other timing effects, the proper motion signatures persist even in systems with zero eccentricity and get stronger as the planetary period increases. They should be the dominant cause of transit-timing variations in isolated wide-separation (periods of months) systems that will be sought by Kepler.

  4. Proper Motions in Sunspot Penumbrae: Signs of Convection

    NASA Astrophysics Data System (ADS)

    Bonet, J. A.; Márquez, I.; Sánchez Almeida, J.

    2006-12-01

    Proper motions in penumbra have been measured using local correlation tracking techniques in a high spatial resolution series of images (˜0.12 arcsec). Assuming these motions to trace true plasma motions, we have detected converging flows that arrange the plasma in long narrow filaments mostly placed along dark penumbral filaments. These converging flows suggest downflows in the filaments of ˜ 200 m s-1. We interpret the association between downflows and dark features as a sign of convection that, once several observational biases are considered, could transport enough energy to balance the radiative losses of penumbra.

  5. Photometric calibration of the APM Proper Motion Project

    NASA Astrophysics Data System (ADS)

    Evans, D. W.

    1989-05-01

    Deep BVR photometry is presented in the magnitude range B = 11-21, obtained using a CCD camera. These magnitudes are used to calibrate the photographic photometry of the APM Proper Motion Project. Useful color-color relationships are also presented, calculated using the stellar spectra of Gunn and Stryker (1983).

  6. GLIMPSE Proper: Mid-Infrared Observations of Proper Motion and Variability Towards Galactic Center

    NASA Astrophysics Data System (ADS)

    Benjamin, Robert; Babler, Brian; Churchwell, Ed; Clarkson, Will; Kirkpatrick, Davy; Meade, Marilyn; Whitney, Barbara

    2015-10-01

    We propose to re-image 43.4 square degrees of the Galactic center to measure the proper motions of over fifteen million sources within 5 degrees of Galactic center over the last decade. This stellar sample will be over 20 times larger than the previous optical ground-based measurements and will allow us to constrain the anisotropic stellar velocity dispersion as a function of direction and distance as well as test previous claims of streaming motions associated with the near/far side of the Galactic bar, the X-shaped bar, and the vertically thin extended Long Bar. Not only will this be the largest Galactic bulge proper motion survey to date, it will also be the most uniform as mid-infrared observations are minimally affected by extinction over most of the region. We also expect to find at least 150 high proper motion stars (>100 mas/yr) which could be substellar objects and possible microlensing candidates against the crowded Galactic bulge. We will put constraints on the current production rate of hyper-velocity stars thought to be formed in binary interactions with the supermassive black hole of the Galaxy. Finally, we will be able to identify many new variable stars, particularly in the central 2x1.5 degree region of the Galaxy which has only been observed in a single epoch with Spitzer; we expect to find 1000 new sources with variability amplitudes greater than 0.2 mag.

  7. Emerging Flux Tube Geometry and Sunspot Proper Motions

    NASA Astrophysics Data System (ADS)

    van Driel-Gesztelyi, Lidia

    As sunspots appear at the intersection of rising flux tubes with the photosphere, the observed proper motions of a bipolar sunspot pair is a good indicator of the geometry of the underlying emerging flux tube. An emerging bipole caused by a simple symmetric potential flux tube should display a symmetric divergence of the two spots in diametrically opposite directions, while the proper motions of bipolar spot-pairs belonging to tilted or/and twisted (non-potential) emerging flux tubes are more complicated: asymmetric, not diametrically opposite and may follow a curved pattern. Observation of such motions may help to prove that emerging flux tubes are tilted and frequently twisted, in good agreement with predictions by recent simulation studies.

  8. Vertical velocities from proper motions of red clump giants

    NASA Astrophysics Data System (ADS)

    López-Corredoira, M.; Abedi, H.; Garzón, F.; Figueras, F.

    2014-12-01

    Aims: We derive the vertical velocities of disk stars in the range of Galactocentric radii of R = 5 - 16 kpc within 2 kpc in height from the Galactic plane. This kinematic information is connected to dynamical aspects in the formation and evolution of the Milky Way, such as the passage of satellites and vertical resonance and determines whether the warp is a long-lived or a transient feature. Methods: We used the PPMXL survey, which contains the USNO-B1 proper motions catalog cross-correlated with the astrometry and near-infrared photometry of the 2MASS point source catalog. To improve the accuracy of the proper motions, the systematic shifts from zero were calculated by using the average proper motions of quasars in this PPMXL survey, and we applied the corresponding correction to the proper motions of the whole survey, which reduces the systematic error. From the color-magnitude diagram K versus (J - K) we selected the standard candles corresponding to red clump giants and used the information of their proper motions to build a map of the vertical motions of our Galaxy. We derived the kinematics of the warp both analytically and through a particle simulation to fit these data. Complementarily, we also carried out the same analysis with red clump giants spectroscopically selected with APOGEE data, and we predict the improvements in accuracy that will be reached with future Gaia data. Results: A simple model of warp with the height of the disk zw(R,φ) = γ(R - R⊙)sin(φ - φw) fits the vertical motions if dot {γ }/γ = -34±17 Gyr-1; the contribution to dot {γ } comes from the southern warp and is negligible in the north. If we assume this 2σ detection to be real, the period of this oscillation is shorter than 0.43 Gyr at 68.3% C.L. and shorter than 4.64 Gyr at 95.4% C.L., which excludes with high confidence the slow variations (periods longer than 5 Gyr) that correspond to long-lived features. Our particle simulation also indicates a probable abrupt decrease

  9. Common proper motion stars in the AGK 3

    NASA Astrophysics Data System (ADS)

    Halbwachs, J. L.

    1986-11-01

    A search was made of common proper motion (CPM) systems among AGK 3 stars. The selection of physical systems was based upon the ratio between the angular separation, ρ, and the proper motion, μ; the CPM stars found are presented in two tables: Table I lists systems with ρ/μ less than 103years. It contains 326 entries and the proportion of optical pairs is estimated to be 1%. Table II lists systems with ρ/μ in the range 1000 to 3500 years; it contains 113 systems, but only 60% of them are physical. Nevertheless these systems often have separations larger than 10000 AU and are the most interesting for the study of the tail of the distribution function of the semi-major axes.

  10. Star catalog position and proper motion corrections in asteroid astrometry

    NASA Astrophysics Data System (ADS)

    Farnocchia, D.; Chesley, S. R.; Chamberlin, A. B.; Tholen, D. J.

    2015-01-01

    We provide a scheme to correct asteroid astrometric observations for star catalog systematic errors due to inaccurate star positions and proper motions. As reference we select the most accurate stars in the PPMXL catalog, i.e., those based on 2MASS astrometry. We compute position and proper motion corrections for 19 of the most used star catalogs. The use of these corrections provides better ephemeris predictions and improves the error statistics of astrometric observations, e.g., by removing most of the regional systematic errors previously seen in Pan-STARRS PS1 asteroid astrometry. The correction table is publicly available at ftp://ssd.jpl.nasa.gov/pub/ssd/debias/debias_2014.tgz and can be freely used in orbit determination algorithms to obtain more reliable asteroid trajectories.

  11. Proper motion of the Large Magellanic Cloud and the mass of the galaxy. 1: Observational results

    NASA Astrophysics Data System (ADS)

    Jones, B. F.; Klemola, A. R.; Lin, D. N. C.

    1994-04-01

    We have measured the proper motion of the Large Magellanic Cloud (LMC) using 21 plates taken with the Cerro-Tololo Inter-American Observatory (CTIO) 4 m telescope and covering an epoch span of 14 yr. The plates were centered on the globular cluster NGC 2257, lying on the northeast periphery of the Cloud. Proper motions were determined for 251 LMC members, chosen on the basis of the photometry of Stryker (1984), using 92 galaxies as a reference frame. The measured mean absolute proper motion of the LMC stars in our region is mualpha = 0.120 sec +/- 0.028 sec century-1, mudelta=0.026 sec +/- 0.027 sec century-1. After correcting for the rotation of the LMC and the effects of solar motion, this proper motion combined with the radial velocity of the LMC implies a galactocentric coordinate radial velocity for the Cloud of 48 +/- 41 km s-1 and a total galactocentric transverse velocity of 215 +/- 48 km s-1.

  12. Proper motions of embedded protostellar jets in Serpens

    NASA Astrophysics Data System (ADS)

    Djupvik, A. A.; Liimets, T.; Zinnecker, H.; Barzdis, A.; Rastorgueva-Foi, E. A.; Petersen, L. R.

    2016-03-01

    Aims: We determine the proper motion of protostellar jets around Class 0 and Class I sources in an active star forming region in Serpens. Methods: Multi-epoch deep images in the 2.122 μm line of molecular hydrogen, v = 1-0 S(1), obtained with the near-infrared instrument NOTCam on a timescale of 10 years, are used to determine the proper motion of knots and jets. K-band spectroscopy of the brighter knots is used to supply radial velocities, estimate extinction, excitation temperature, and H2 column densities towards these knots. Results: We measure the proper motion of 31 knots on different timescales (2, 4, 6, 8, and 10 years). The typical tangential velocity is around 50 km s-1 for the 10-year baseline, but for shorter timescales, a maximum tangential velocity up to 300 km s-1 is found for a few knots. Based on morphology, velocity information, and the locations of known protostars, we argue for the existence of at least three partly overlapping and deeply embedded flows, one Class 0 flow and two Class I flows. The multi-epoch proper motion results indicate time-variable velocities of the knots, for the first time directly measured for a Class 0 jet. We find in general higher velocities for the Class 0 jet than for the two Class I jets. While the bolometric luminosites of the three driving sources are about equal, the derived mass flow rate Ṁout is two orders of magnitude higher in the Class 0 flow than in the two Class I flows. Based on observations made with the Nordic Optical Telescope, operated on the island of La Palma jointly by Denmark, Finland, Iceland, Norway, and Sweden, in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofisica de Canarias.

  13. Using dwarf satellite proper motions to determine their origin

    NASA Astrophysics Data System (ADS)

    Angus, G. W.; Diaferio, Antonaldo; Kroupa, Pavel

    2011-09-01

    The highly organized distribution of satellite galaxies surrounding the Milky Way is a serious challenge to the concordance cosmological model. Perhaps the only remaining solution, in this framework, is that the dwarf satellite galaxies fall into the Milky Way's potential along one or two filaments, which may or may not plausibly reproduce the observed distribution. Here we test this scenario by making use of the proper motions of the Fornax, Sculptor, Ursa Minor and Carina dwarf spheroidals, and trace their orbits back through several variations of the Milky Way's potential and account for dynamical friction. The key parameters are the proper motions and total masses of the dwarf galaxies. Using a simple model, we find no tenable set of parameters that can allow Fornax to be consistent with filamentary infall, mainly because the 1σ error on its proper motion is relatively small. The other three must walk a tightrope between requiring a small pericentre (less than 20 kpc) to lose enough orbital energy to dynamical friction and avoiding being tidally disrupted. We then employed a more realistic model with host halo mass accretion and found that the four dwarf galaxies must have fallen in at least 5 Gyr ago. This time-interval is longer than organized distribution is expected to last before being erased by the randomization of the satellite orbits.

  14. THE SPACE MOTION OF LEO I: HUBBLE SPACE TELESCOPE PROPER MOTION AND IMPLIED ORBIT

    SciTech Connect

    Sohn, Sangmo Tony; Van der Marel, Roeland P.; Besla, Gurtina; Boylan-Kolchin, Michael; Bullock, James S.; Majewski, Steven R.

    2013-05-10

    We present the first absolute proper motion measurement of Leo I, based on two epochs of Hubble Space Telescope ACS/WFC images separated by {approx}5 years in time. The average shift of Leo I stars with respect to {approx}100 background galaxies implies a proper motion of ({mu}{sub W}, {mu}{sub N}) = (0.1140 {+-} 0.0295, -0.1256 {+-} 0.0293) mas yr{sup -1}. The implied Galactocentric velocity vector, corrected for the reflex motion of the Sun, has radial and tangential components V{sub rad} = 167.9 {+-} 2.8 km s{sup -1} and V{sub tan} = 101.0 {+-} 34.4 km s{sup -1}, respectively. We study the detailed orbital history of Leo I by solving its equations of motion backward in time for a range of plausible mass models for the Milky Way (MW) and its surrounding galaxies. Leo I entered the MW virial radius 2.33 {+-} 0.21 Gyr ago, most likely on its first infall. It had a pericentric approach 1.05 {+-} 0.09 Gyr ago at a Galactocentric distance of 91 {+-} 36 kpc. We associate these timescales with characteristic timescales in Leo I's star formation history, which shows an enhanced star formation activity {approx}2 Gyr ago and quenching {approx}1 Gyr ago. There is no indication from our calculations that other galaxies have significantly influenced Leo I's orbit, although there is a small probability that it may have interacted with either Ursa Minor or Leo II within the last {approx}1 Gyr. For most plausible MW masses, the observed velocity implies that Leo I is bound to the MW. However, it may not be appropriate to include it in models of the MW satellite population that assume dynamical equilibrium, given its recent infall. Solution of the complete (non-radial) timing equations for the Leo I orbit implies an MW mass M{sub MW,vir} = 3.15{sub -1.36}{sup +1.58} x 10{sup 12} M{sub Sun }, with the large uncertainty dominated by cosmic scatter. In a companion paper, we compare the new observations to the properties of Leo I subhalo analogs extracted from cosmological

  15. Spectrophotometric characterization of high proper motion sources from WISE

    NASA Astrophysics Data System (ADS)

    Beamín, J. C.; Ivanov, V. D.; Minniti, D.; Smart, R. L.; Mužić, K.; Mendez, R. A.; Beletsky, Y.; Bayo, A.; Gromadzki, M.; Kurtev, R.

    2015-12-01

    The census of the solar neighbourhood is almost complete for stars and becoming more complete in the brown dwarf regime. Spectroscopic, photometric and kinematic characterization of nearby objects helps us to understand the local mass function, the binary fraction, and provides new targets for sensitive planet searches. We aim to derive spectral types and spectrophotometric distances of a sample of new high proper motion sources found with the WISE (Wide-field Infrared Survey Explorer) satellite, and obtain parallaxes for those objects that fall within the area observed by the Vista Variables in the Vía Láctea survey (VVV). We used low-resolution spectroscopy and template fitting to derive spectral types, multiwavelength photometry to characterize the companion candidates and obtain photometric distances. Multi-epoch imaging from the VVV survey was used to measure the parallaxes and proper motions for three sources. We confirm a new T2 brown dwarf within ˜15 pc. We derived optical spectral types for 24 sources, mostly M dwarfs within 50 pc. We addressed the wide binary nature of 16 objects found by the WISE mission and previously known high proper motion sources. Six of these are probably members of wide binaries, two of those are new, and present evidence against the physical binary nature of two candidate binary stars found in the literature, and eight that we selected as possible binary systems. We discuss a likely microlensing event produced by a nearby low-mass star and a galaxy, that is to occur in the following five years.

  16. uvby photometry in McCormick proper motion fields

    NASA Technical Reports Server (NTRS)

    Degewij, J.

    1982-01-01

    The Danish 50 cm telescope at the European Southern Observatory was used to obtain high-precision uvby photometry for 50 F2 to G2 stars, with V values in the 9.4-12.3 mag range, which were selected in the southern galactic polar regions of the McCormick proper motion fields and measured on six different nights. The brighter stars are found to systematically exhibit smaller m(1) indices, of about 0.02 mag, upon comparison with the earlier data of Blaauw et al (1976). Single measurements are given for 98 stars in eight McCormick fields at intermediate southern galactic latitudes.

  17. Proper Motion Probe of the Galaxy in the Anticentre Direction

    NASA Astrophysics Data System (ADS)

    Chareton, M.; Considere, S.; Bienayme, O.

    1993-12-01

    We present a new proper motion probe as part of an investigation of galactic structure and evolution. We discuss the observational results obtained in a restricted field of 1.77 square degrees at low galactic latitude in the direction of SpA 23 (t = 179°., 6 = 2.8°). The resulting catalogue includes 24765 stars. It is complete down to magnitudes 19, 19 and 18 respectively in U, B and V passbands. Photographic photometry have been published separately (Mohan et al. 1988).

  18. Proper Motions of Massive Stars in 30 Doradus

    NASA Astrophysics Data System (ADS)

    Lennon, Daniel

    2013-10-01

    We propose an ambitious proper motion survey of massive stars in the 30 Doradus region of the Large Magellanic Cloud using the unique capabilities of HST. We will derive the directions of motion of massive runaway stars, searching in particular for massive stars which have been ejected from the central very massive cluster R136. These data will be combined with radial velocities from the VLT-FLAMES Survey of the Tarantula Nebula and with atmospheric analyses and stellar evolution models to constrain their origins. We will also search for very young isolated massive stars to test models of single-star formation. This work is highly relevant to star formation, cluster dynamics, the origin of field WR stars and GRBs, the creation of very massive stars by runaway mergers, and the possible formation of intermediate-mass black holes.

  19. PROPER MOTIONS OF THE HH 110/270 SYSTEM

    SciTech Connect

    Kajdic, P.; Reipurth, B.; Walawender, J.; Raga, A. C.; Bally, J. E-mail: reipurth@IfA.Hawaii.Edu E-mail: John.Bally@casa.colorado.edu

    2012-05-15

    We present a study of the HH 110/270 system based on three sets of optical images obtained with the ESO New Technology Telescope, the Subaru Telescope, and the Hubble Space Telescope (HST). The ground-based observations are made in the H{alpha} and [S II] emission lines and the HST observations are made in the H{alpha} line only. Ground-based observations reveal the existence of nine knots, which have not been previously discussed and offer some important insight into the HH 110/270 history. We perform a kinematic study of the HH 110/270 system and an analysis of its emission properties. We measure proper motions of all the knots in the system. Four of the newly identified knots belong to the HH 270 jet. Their positions indicate that the jet's axis changed its direction in the past. We speculate that similar changes may have occurred many times in the past and this could be part of the reason for the unusual structure of the HH 110 jet. The HST observations allow us to resolve individual knots into their substructures and to measure their proper motions. These measurements show that the knots are highly turbulent structures. Finally, we report the discovery of four new Herbig-Haro (HH) objects located near the HH 110/270 system.

  20. Constraining the Mass of the Local Group through Proper Motion Measurements of Local Group Galaxies

    NASA Astrophysics Data System (ADS)

    Sohn, S. Tony; van der Marel, R.; Anderson, J.

    2012-01-01

    The Local Group and its two dominant spiral galaxies have been the benchmark for testing many aspects of cosmological and galaxy formation theories. This includes, e.g., dark halo profiles and shapes, substructure and the "missing satellite" problem, and the minimum mass for galaxy formation. But despite the extensive work in all of these areas, our knowledge of the mass of the Milky Way and M31, and thus the total mass of the Local Group remains one of the most poorly established astronomical parameters (uncertain by a factor of 4). One important reason for this problem is the lack of information in tangential motions of galaxies, which can be only obtained through proper motion measurements. In this study, we introduce our projects for measuring absolute proper motions of (1) the dwarf spheroidal galaxy Leo I, (2) M31, and (3) the 4 dwarf galaxies near the edge of the Local Group (Cetus, Leo A, Tucana, and Sag DIG). Results from these three independent measurements will provide important clues to the mass of the Milky Way, M31, and the Local Group as a whole, respectively. We also present our proper motion measurement technique that uses compact background galaxies as astrometric reference sources.

  1. Large proper motions of the Herbig-Haro objects HH 1 and HH 2

    NASA Astrophysics Data System (ADS)

    Herbig, G. H.; Jones, B. F.

    1981-08-01

    Crossley and 120-in. direct plates obtained between 1946 and 1980 have been measured for the proper motions of the Herbig-Haro objects HH 1, HH 2, and HH 3, which were then referred to the motion of the Orion complex. HH 3 is found to be essentially stationary, while HH 1 and HH 2 have large cross motions in opposite directions, diverging from the position of a faint, red Orion association member which Cohen and Schwartz (1979) have proposed as the exciting star of HH 1. While most of the individual nuclei within each HH object are moving parallel to one another, there is a considerable dispersion in speeds: 155-351 km/sec for HH 1 and 100-294 km/sec for HH 2. A discrepancy is seen between absolute tangential velocities and the relative velocities of gas flowing into the shock front that are inferred from the optical spectra and shock model theory.

  2. Forward Shock Proper Motions of Kepler's Supernova Remnant

    NASA Astrophysics Data System (ADS)

    Katsuda, S.; Tsunemi, H.; Uchida, H.; Kimura, M.

    2008-12-01

    The X-ray structure of Kepler's supernova remnant shows a rounded shape delineated by forward shocks. We measure proper motions of the forward shocks on overall rims of the remnant, by using archival Chandra data taken in two epochs with time difference of 6.09 yr. The proper motions of the forward shocks on the northern rim are measured to be 0.076'' (±0.032'' ±0.016'') to 0.11'' (±0.014'' ±0.016'') yr-1, while those on the rest of the rims are measured to be 0.15'' (±0.017'' ±0.016'') to 0.30'' (±0.048'' ±0.016'') yr-1 here the first-term errors are statistical uncertainties and the second-term errors are systematic uncertainties. Combining the best-estimated shock velocity of 1660 +/- 120 km s-1 measured for Balmer-dominated filaments in the northern and central portions of the remnant (Sankrit et al. 2005) with the proper motions derived for the forward shocks on the northern rim, we estimate a distance of 3.3+1.6-0.4 kpc to the remnant. We measure the expansion indices, m (defined as R propto tm), to be 0.47-0.82 for most of the rims. These values are consistent with those expected in Type Ia SN explosion models, in which the ejecta and the circumstellar medium have power-law density profiles whose indices are 5-7 and 0-2, respectively. In addition, we should note the slower expansion on the northern rim than that on the southern rim. This is likely caused by the inhomogeneous circumstellar medium; the density of the circumstellar medium is higher in the north than that in the south of the remnant. The newly estimated geometric center, around which we believe the explosion point exists, is located at ~5'' offset to the north of the radio center.

  3. Search for high-proper motion objects with infrared excess

    NASA Astrophysics Data System (ADS)

    Teodorani, Massimo

    2014-12-01

    The possibility of interstellar migration has been theorized during the past thirty years in the form of 'Dysonships' that, using non-relativistic propulsion systems, are able to colonize the Galaxy in a relatively short time compared to the age of the Galaxy and consequently penetrate inside our solar system too. Observational evidence of this can be potentially obtained using the present state of the art of telescopes and related sensors, by following aimed searches and an expanded SETI protocol. Some transient and unrepeated radio signals recorded during standard SETI observations might be due to the transit of high-proper motion artificial sources of extraterrestrial origin, which are expected to show a very weak optical emission, a strong infrared excess and occasional high-energy bursts in the X and Gamma-ray wavelength ranges. Such artificial sources might show an interest to Earth by sending probes to visit it: such a possibility can be investigated scientifically as well.

  4. The proper motion VS redshift relation for superluminal radio sources

    NASA Astrophysics Data System (ADS)

    Rust, Bert W.; Nash, Stephen G.; Geldzahler, Barry J.

    1989-02-01

    The proper motion vs redshift relation has been analyzed for the data set of Zensus and Pearson (1988). A nonlinearly constrained nonlinear optimization program is used to estimate the lower envelope as a constrained maximum likelihood problem, with the constraints specified by the expected value of the largest order statistics for the estimated angle of inclination. The present estimation procedure yields a value of H = 103 km/s per Mpc for the light echo model and a value of H = 46 km/s per Mpc for the dipole field models. In all the cases considered, a large excess of sources is found at low-inclinations angles (high apparent velocities), suggesting a strong contamination of the sample by relativistic beam sources which would only be seen at low inclination angles.

  5. Accretion History and Mass of the Milky Way Halo: HST Proper Motions and Keck Spectra

    NASA Astrophysics Data System (ADS)

    Cunningham, Emily C.; Deason, A. J.; Guhathakurta, P.; Rockosi, C. M.; Barro, G.; Van Der Marel, R. P.; Sohn, S.; Anderson, J.; HSTPROMO Collaboration; HALO7D Collaboration

    2014-01-01

    The Milky Way (MW) is shrouded in a faint metal-poor stellar halo. Its structure and kinematics provide a unique archaeological record of the MW's formation, past evolution, and accretion history. These data also help us constrain the dark matter mass out to large radii (50 to 100 kpc). The stellar density profile and line-of-sight velocity dispersion profile of the halo are known, but our understanding of the halo is limited by a striking lack of knowledge about the transverse motions of its stars. It is difficult from the ground to determine proper motions (PMs) far outside of the solar neighborhood. We have recently developed techniques for making PM measurements from multi-epoch Hubble Space Telescope (HST) data using distant background galaxies to define an absolute astrometric reference frame. We will obtain very deep (8 to 24 hr integrations) Keck II 10-m telescope/DEIMOS spectra of hundreds of faint Milky Way halo stars with HST-measured proper motions, to measure their line-of-sight velocities and chemical abundances, giving us 6D phase-space information plus chemical abundance information. Our primary fields of interest include the CANDELS HST/MCT program fields GOODS-N, COSMOS, and EGS. These fields are characterized by deep HST photometry at wavelengths ranging from the ultraviolet to the infrared. This dataset, which will be unique even in the era of Gaia, will vastly improve our understanding of the Milky Way structure, evolution and mass in a way that neither the HST proper motions or Keck spectroscopy can do on their own. This research is part of two large collaborations: The HST Proper Motion (HSTPROMO) collaboration and the Halo Assembly in Lambda-CDM: Observations in 7-Dimensions (HALO7D). We acknowledge financial support from the National Science Foundation and NASA.

  6. Halley's Discovery of Stellar Proper Motion: The Aldebaran Problem

    NASA Astrophysics Data System (ADS)

    Brandt, John C.

    2009-01-01

    Halley (1717) compared contemporary positions of Arcturus, Sirius, and Aldebaran with the ancient positions recorded in the Almagest (Book VII 3) and attributed to Timocharis, Hipparcus, and Ptolemy. He found that these stars had apparently moved southward by more than 30 arc minutes and concluded that these stars had their own particular motions. Modern proper motion measurements are consistent with this conclusion for Arcturus and Sirius, but are not even close for Aldebaran. While some authors (Fomenko et al. 1993; Evans 1998) are aware of the problem, it generally is not mentioned in books on the history of astronomy (e.g., Clerke 1908; Pannekoek 1961; Neugebauer 1975) or in the major biographies of Halley (Armitage 1966; Ronan 1969; Lancaster-Brown 1985; Cook 1998). None of the possibilities for resolving this problem_errors in the ancient and/or the 17th-18th century positions; errors in Halley's calculations; or misidentification of the star--- seem plausible and final resolution may require locating the original calculations in Halley's papers.

  7. SIMP: A Near-Infrared Proper Motion Survey

    NASA Astrophysics Data System (ADS)

    Artigau, Étienne; Lafrenière, David; Doyon, René; Albert, Loïc; Robert, Jasmin; Malo, Lison

    2009-02-01

    SIMP is a proper motion (PM) survey made with the Observatoire du Mont Mégantic (OMM) wide-field near-infrared camera CPAPIR at the CTIO 1.5 m and OMM 1.6 m telescopes. The SIMP observations were initiated in early 2005, are still ongoing and, to date, have covered 28% of the sky at high galactic latitudes. The PMs of the sources detected are determined by comparing their measured positions with those listed in the 2MASS point source catalog, giving a time baseline of 4 to 10 years. The 5 σ uncertainty on the relative SIMP and 2MASS astrometry is 1'', equivalent to a PM lower limit of 0.125-0.250''/yr, or a tangential velocity limit of 15-30 km/s at 25 pc. Up to the 2MASS magnitude limit (J~16.5), T dwarfs are found out to ~25 pc, while L dwarfs may be found as far as 100 pc away.

  8. Proper Motions of Isolated Massive Stars Near the Galactic Center

    NASA Astrophysics Data System (ADS)

    Lennon, Daniel

    2014-10-01

    The Galactic Center is one of the most perplexing and unusual regions of the Galaxy. Not only is it home to the central massive black hole but it contains three very massive young star clusters within the central 30 pc; the Arches, Quintuplet and Central clusters. Furthermore, emission-line surveys have revealed the presence of what appears to be a diaspora of ~40 very massive isolated Wolf-Rayet-like stars scattered throughout the region, outside of these massive clusters. Their origin is currently unkown but the suspected causes include such diverse and exotic mechanisms as ejection by dynamical interaction within the massive clusters, ejection by supernovae events within those clusters old enough to have SN, ejection by interaction with the central black hole, stellar mergers in the field, and in situ star formation of isolated massive stars. These processes however should all leave clear and distinct dynamical signatures on their products.We propose using WFC3/IR to conduct a survey of ~150 square arcminutes the Galactic Center region to measure relative proper motions to an accuracy of 10 km/s for stars with masses as low as a few solar masses (late B-type). Our objectives include determining which of the known isolated massive stars are runaways, estimating their probable places of origin, discovering less luminous runaways that are invisible to emission line surveys, characterizing the dynamical properties of runaway stars in all luminosty ranges, and searching for signs of tidally disrupted massive clusters. The survey will have lasting legacy value to those trying to unravel the physics of galactic centers and the environments around massive black holes.

  9. Proper Motions of Isolated Massive Stars Near the Galactic Center

    NASA Astrophysics Data System (ADS)

    Lennon, Daniel

    2012-10-01

    The Galactic Center is one of the most perplexing and unusual regions of the Galaxy. Not only is it home to the central massive black hole but it contains three very massive young star clusters within the central 30 pc; the Arches, Quintuplet and Central clusters. Furthermore, emission-line surveys have revealed the presence of what appears to be a diaspora of 40 very massive isolated Wolf-Rayet-like stars scattered throughout the region, outside of these massive clusters. Their origin is currently unkown but the suspected causes include such diverse and exotic mechanisms as ejection by dynamical interaction within the massive clusters, ejection by supernovae events within those clusters old enough to have SN, ejection by interaction with the central black hole, stellar mergers in the field, and in situ star formation of isolated massive stars. These processes however should all leave clear and distinct dynamical signatures on their products.We propose using WFC3/IR to conduct a survey of 150 square arcminutes the Galactic Center region to measure relative proper motions to an accuracy of 10 km/s for stars with masses as low as a few solar masses {late B-type}. Our objectives include determining which of the known isolated massive stars are runaways, estimating their probable places of origin, discovering less luminous runaways that are invisible to emission line surveys, characterizing the dynamical properties of runaway stars in all luminosty ranges, and searching for signs of tidally disrupted massive clusters. The survey will have lasting legacy value to those trying to unravel the physics of galactic centers and the environments around massive black holes.

  10. Precession Constant Correction and Proper Motion Systems of FK5 and Hipparcos

    NASA Astrophysics Data System (ADS)

    Zhu, Zi

    2007-07-01

    Results of many researches have shown that the relation between the proper motion systems of FK5 and Hipparcos is not consistent with the precession constant corrections determined by VLBI and LLR. We analysed proper motion data of PPM and ACRS based on the FK5 system for many different sub-samples and found that consistent values of the precession correction and equinox motion correction can not be given by either PPM or ACRS proper motion data, thereby indicating that the internal systematic error of the FK5 proper motion is the main underlying factor of the inconsistency.

  11. Precessional correction and the proper-motion systems of FK5 and Hipparcos

    NASA Astrophysics Data System (ADS)

    Zhu, Z.

    2006-10-01

    Comparing proper motions of the FK5 and Hipparcos, several authors declared that the two proper-motion systems are inconsistent with the value of the precessional correction obtained from VLBI and LLR observations. Based on the proper-motion data from the PPM and ACRS catalogues which are constructed on the FK5 system, the discrepant values of the precessional correction and of the correction of the equinoctial motion, derived from the different subsets of stellar samples, have be found. One of the reasons for those discrepancies should be mostly due to the internal biased proper-motion system of the FK5.

  12. PROPER MOTIONS IN KAPTEYN SELECTED AREA 103: A PRELIMINARY ORBIT FOR THE VIRGO STELLAR STREAM

    SciTech Connect

    Casetti-Dinescu, Dana I.; Girard, Terrence M.; Van Altena, William F.; Majewski, Steven R.; Carlin, Jeffrey L.; Vivas, A. Katherina; Wilhelm, Ronald; Beers, Timothy C.

    2009-08-10

    We present absolute proper motions in Kapteyn Selected Area (SA) 103. This field is located 7 deg. west of the center of the Virgo Stellar Stream (VSS), and has a well-defined main sequence representing the stream. In SA 103, we identify one RR Lyrae star as a member of the VSS, according to its metallicity, radial velocity, and distance. VSS candidate turnoff and subgiant stars have proper motions consistent with that of the RR Lyrae star. The three-dimensional velocity data imply an orbit with a pericenter of {approx}11 kpc and an apocenter of {approx}90 kpc. Thus, the VSS comprises tidal debris found near the pericenter of a highly destructive orbit. Examining the six globular clusters at distances larger than 50 kpc from the Galactic center, and the proposed orbit of the VSS, we find one tentative association, NGC 2419. We speculate that NGC 2419 is possibly the nucleus of a disrupted system of which the VSS is a part.

  13. The understanding of the FK5 and Hipparcos proper-motion systems†

    NASA Astrophysics Data System (ADS)

    Zhu, Z.

    2008-07-01

    Comparing proper motions of the FK5 and Hipparcos, several authors declared that the two proper-motion systems are inconsistent with the value of the precession correction obtained from VLBI and LLR observations. Based on the proper-motion data from the PPM and ACRS catalogues which are constructed on the FK5 system, the inconsistent values of the precessional correction and of the time-dependent term of equinox correction, derived from the different subsets of stellar samples, have been found. One of the reasons for those discrepancies should be mostly due to the internally biased proper-motion system of the FK5.

  14. The far distance to G7.47+0.06 from proper motion measurement of H2O masers

    NASA Astrophysics Data System (ADS)

    Yamauchi, Aya; Yamashita, Kazuyoshi; Honma, Mareki; Sunada, Kazuyoshi; Nakagawa, Akiharu; Ueno, Yuji

    2016-08-01

    We report on a distance measurement of 22 GHz H2O maser features associated with an ultra-compact H II region G7.47+0.06 using VERA (VLBI Exploration of Radio Astrometry). Since the source is located farther away than 10 kpc, it turned out to be difficult to derive the distance from annual parallax measurement. Meanwhile, we clearly detected the source's proper motion parallel to the Galactic plane. The proper motion is μ = -5.03 ± 0.07 mas yr-1 and is approaching the Galactic center. We applied a new method to determine the source distance based on absolute proper motions. Considering uncertainties of the Galactic rotation curve and the solar peculiar motion, the detected proper motion leads to a source distance of D = 20 ± 2 kpc, demonstrating that astrometric observation can provide an accurate distance measurement at a 10% level even for sources too distant to measure the annual parallax. Lastly, we scale the physical parameters of the H II region estimated in a previous paper to be 20 kpc, and show that the H2O maser features are associated with a massive star-forming region corresponding to the spectral type of O5.5.

  15. The far distance to G7.47+0.06 from proper motion measurement of H2O masers

    NASA Astrophysics Data System (ADS)

    Yamauchi, Aya; Yamashita, Kazuyoshi; Honma, Mareki; Sunada, Kazuyoshi; Nakagawa, Akiharu; Ueno, Yuji

    2016-06-01

    We report on a distance measurement of 22 GHz H2O maser features associated with an ultra-compact H II region G7.47+0.06 using VERA (VLBI Exploration of Radio Astrometry). Since the source is located farther away than 10 kpc, it turned out to be difficult to derive the distance from annual parallax measurement. Meanwhile, we clearly detected the source's proper motion parallel to the Galactic plane. The proper motion is μ = -5.03 ± 0.07 mas yr-1 and is approaching the Galactic center. We applied a new method to determine the source distance based on absolute proper motions. Considering uncertainties of the Galactic rotation curve and the solar peculiar motion, the detected proper motion leads to a source distance of D = 20 ± 2 kpc, demonstrating that astrometric observation can provide an accurate distance measurement at a 10% level even for sources too distant to measure the annual parallax. Lastly, we scale the physical parameters of the H II region estimated in a previous paper to be 20 kpc, and show that the H2O maser features are associated with a massive star-forming region corresponding to the spectral type of O5.5.

  16. The calculation of an equation of magnitude for determining the proper motions of stars

    NASA Astrophysics Data System (ADS)

    Kharchenko, N. V.

    A method is proposed for correcting errors in magnitude equations for the proper motion of stars using only catalog data. An independent catalog of proper motion is obtained by calculating the local motion of stars within individual areas. The method can be applied to any catalog of stellar proper motions, including the AGK-3 catalog. Estimates of error are obtained for stellar magnitudes in the Goloseyev catalog of stellar proper motions relative to galaxies. The method is also applied to equations of proper motion obtained from photographs taken by the double long-focusing astrograph of the Main Astronomical Observatory of the Ukrainian SSR Academy of Sciences in the interval of stellar magnitudes between 10 and 15 mag. Values are obtained for the large degree of difference observed between temperature and type of plate.

  17. The VMC survey. XVII. Proper motions of the Small Magellanic Cloud and the Milky Way globular cluster 47 Tucanae

    NASA Astrophysics Data System (ADS)

    Cioni, Maria-Rosa L.; Bekki, Kenji; Girardi, Léo; de Grijs, Richard; Irwin, Mike J.; Ivanov, Valentin D.; Marconi, Marcella; Oliveira, Joana M.; Piatti, Andrés E.; Ripepi, Vincenzo; van Loon, Jacco Th.

    2016-02-01

    Aims: In this study we use multi-epoch near-infrared observations from the VISTA survey of the Magellanic Cloud system (VMC) to measure the proper motions of different stellar populations in a tile of 1.5 deg2 in size in the direction of the Galactic globular cluster 47 Tuc. We obtain the proper motion of the cluster itself, of the Small Magellanic Cloud (SMC), and of the field Milky Way stars. Methods: Stars of the three main stellar components are selected according to their spatial distributions and their distributions in colour-magnitude diagrams. Their average coordinate displacement is computed from the difference between multiple Ks-band observations for stars as faint as Ks = 19 mag. Proper motions are derived from the slope of the best-fitting line among ten VMC epochs over a time baseline of ~1 yr. Background galaxies are used to calibrate the absolute astrometric reference frame. Results: The resulting absolute proper motion of 47 Tuc is (μαcos(δ), μδ) = (+7.26 ± 0.03, -1.25 ± 0.03) mas yr-1. This measurement refers to about 35 000 sources distributed between 10' and 60' from the cluster centre. For the SMC we obtain (μαcos(δ), μδ) = (+1.16 ± 0.07, -0.81 ± 0.07) mas yr-1 from about 5250 red clump and red giant branch stars. The absolute proper motion of the Milky Way population in the line of sight (l = 305.9, b = -44.9) of this VISTA tile is (μαcos(δ), μδ) = (+10.22 ± 0.14, -1.27 ± 0.12) mas yr-1 and has been calculated from about 4000 sources. Systematic uncertainties associated with the astrometric reference system are 0.18 mas yr-1. Thanks to the proper motion we detect 47 Tuc stars beyond its tidal radius. Based on observations made with VISTA at the Paranal Observatory under program ID 179.B-2003.

  18. PROPER MOTIONS AND INTERNAL DYNAMICS IN THE CORE OF THE GLOBULAR CLUSTER M71

    SciTech Connect

    Samra, Raminder S.; Richer, Harvey B.; Heyl, Jeremy S.; Goldsbury, Ryan; Walker, Gordon; Woodley, Kristin A.; Thanjavur, Karun E-mail: richer@astro.ubc.ca E-mail: heyl@phas.ubc.ca E-mail: kwoodley@phas.ubc.ca

    2012-05-20

    We have used Gemini North together with the NIRI-ALTAIR adaptive optics imager in the H and K bands to explore the core of the Galactic globular cluster M71 (NGC 6838). We obtained proper motions for 217 stars and have resolved its internal proper motion dispersion. Using a 3.8 year baseline, the proper motion dispersion in the core is found to be 179 {+-} 17 {mu}as yr{sup -1}. We find no evidence of anisotropy in the motions and no radial variation in the proper motions with respect to distance from the cluster center. We also set an upper limit on any central black hole to be {approx}150 M{sub Sun} at 90% confidence level.

  19. Optical position and 'proper motion' of the radio source OQ 208

    NASA Astrophysics Data System (ADS)

    Brosche, P.; Geffert, M.

    1981-11-01

    The position and 'proper motion' of OQ 208 has been derived in different catalog systems using plates taken in 1915/1916 and 1979. In an extragalactic reference system, the 'proper motion' is found to be zero within the error limits, while in the AKG system, the 'proper motion' is several tenths of arcsec in 100 years. The position in the FK 4 system (equinox 1950) is estimated as the following: alpha equals 14h04m45.627s and delta equals 28deg41arcmin29.22arcsec.

  20. Age Dependent Absolute Plate and Plume Motion Modeling

    NASA Astrophysics Data System (ADS)

    Heaton, D. E.; Koppers, A. A. P.

    2015-12-01

    Current absolute plate motion (APM) models from 80 - 0 Ma are constrained by the location of mantle plume related hotspot seamounts, in particular those of the Hawaiian-Emperor and Louisville seamount trails. Originally the 'fixed' hotspot hypothesis was developed to explain past plate motion based on linear age progressive intra-plate volcanism. However, now that 'moving' hotspots are accepted, it is becoming clear that APM models need to be corrected for individual plume motion vectors. For older seamount trails that were active between roughly 50 and 80 Ma the APM models that use 'fixed' hotspots overestimate the measured age progression in those trails, while APM models corrected for 'moving' hotspots underestimate those age progressions. These mismatches are due to both a lack of reliable ages in the older portions of both the Hawaii and Louisville seamount trails and insufficient APM modeling constraints from other seamount trails in the Pacific Basin. Seamounts are difficult to sample and analyze because many are hydrothermally altered and have low potassium concentrations. New 40Ar/39Ar Age results from International Ocean Drilling Project (IODP) Expedition 330 Sites U1372 (n=18), U1375 (n=3), U1376 (n=15) and U1377 (n=7) aid in constraining the oldest end of the Louisville Seamount trail. A significant observation in this study is that the age range recovered in the drill cores match the range of ages that were acquired on dredging cruises at the same seamounts (e.g. Koppers et al., 2011). This is important for determining the inception age of a seamount. The sections recovered from IODP EXP 330 are in-situ volcanoclastic breccia and lava flows. Comparing the seismic interpretations of Louisville guyots (Contreras-Reyes et al., 2010), Holes U1372, U1373 and U1374 penetrated the extrusive and volcanoclastic sections of the seamount. The ages obtained are consistent over stratigraphic intervals >100-450 m thick, providing evidence that these seamounts

  1. Identification and Spectral Classification of Red Dwarf Common Proper Motion Binary Stars Part 2

    NASA Astrophysics Data System (ADS)

    Chivers, James

    2014-10-01

    The position angle, separation, and spectral class of 1042 common proper motion red dwarf binary stars are reported based on data-mining the Sloan Digital Sky Survey Data Release 10. 727 of these are new discoveries.

  2. Proper Motions of Water Masers within 1 AU of IRAS 16293-2422

    NASA Astrophysics Data System (ADS)

    Wootten, A.; Marvel, K. B.; Claussen, M.; Wilking, B.

    1999-12-01

    Water masers can be used to trace gas motions in a variety of sources including evolved stars and stars undergoing formation. Recent observations of the water masers associated with two young stellar objects, IRAS 05413-0104 (aka HH212) and S106FIR (Claussen et al 1998 ApJ 507, L79, Furuya et al 1999), have shown that water masers form in shocked gas associated with bipolar outflows from the central forming star. Recent observations (Imai et al. 1999, PASJ 51, 473) have led to the claim that the masers in IRAS 16293-2422 are associated with infalling, rotating gas associated with a circum-protostellar disk. We present proper motion measurements using four epochs of observation with the Very Long Baseline Array, which clearly show proper motions directed away from the central source in IRAS 16293-2422. These motions contradict the expected proper motions for an infalling-rotating gas model for this source.

  3. PARALLAXES AND PROPER MOTIONS OF ULTRACOOL BROWN DWARFS OF SPECTRAL TYPES Y AND LATE T

    SciTech Connect

    Marsh, Kenneth A.; Kirkpatrick, J. Davy; Gelino, Christopher R.; Griffith, Roger L.; Wright, Edward L.; Cushing, Michael C.; Skrutskie, Michael F.; Eisenhardt, Peter R.

    2013-01-10

    We present astrometric measurements of 11 nearby ultracool brown dwarfs of spectral types Y and late-T, based on imaging observations from a variety of space-based and ground-based telescopes. These measurements have been used to estimate relative parallaxes and proper motions via maximum likelihood fitting of geometric model curves. To compensate for the modest statistical significance ({approx}< 7) of our parallax measurements we have employed a novel Bayesian procedure for distance estimation which makes use of an a priori distribution of tangential velocities, V {sub tan}, assumed similar to that implied by previous observations of T dwarfs. Our estimated distances are therefore somewhat dependent on that assumption. Nevertheless, the results have yielded distances for five of our eight Y dwarfs and all three T dwarfs. Estimated distances in all cases are {approx}> 3 pc. In addition, we have obtained significant estimates of V {sub tan} for two of the Y dwarfs; both are <100 km s{sup -1}, consistent with membership in the thin disk population. Comparison of absolute magnitudes with model predictions as a function of color shows that the Y dwarfs are significantly redder in J - H than predicted by a cloud-free model.

  4. Calibrating the Relative Metallicity Scale of M Subdwarfs Using Wide, Common Proper Motion Binaries

    NASA Astrophysics Data System (ADS)

    Dhital, Saurav; Lepine, Sebastien; West, Andrew A.; Stassun, Keivan G.

    2011-08-01

    Metallicity is an important parameter that determines all aspects of stellar evolution and observable properties but is very hard to measure for M dwarfs. M dwarf binaries provide coeval laboratories for studying the properties of the most numerous stellar constituents of the Milky Way; using their common metallicity, we can empirically determine how various molecular indices change with effective temperature. However, despite their ubiquity, M dwarfs are intrinsically faint; previous studies of resolved M dwarf binaries have been limited to small samples, which consist largely of disk dwarfs and are notoriously deficient in metal-poor systems. We propose to observe a sample of ~51 subdwarf (i.e. metal-poor dwarf) binaries to determine how the relative bandstrengths of CaH and TiO vary with metallicity and temperature in low-mass stars. By combining our proposed subdwarf binary sample with previously observed low-mass pairs, we will refine the CaH/TiO-based relative metallicity and probe a large range of metallicity and effective temperature. In addition, we will be able to confirm the binarity of these common proper motion halo pairs and study dynamical evolution/destruction of wide halo binaries. In combination with ongoing companion studies, this will pave the way towards a absolute metallicity scale for M dwarfs and a comprehensive study of chemical and dynamical evolution of the Galaxy.

  5. AN ASYMMETRIC STREAMING MOTION IN THE GALACTIC BULGE X-SHAPED STRUCTURE REVEALED BY OGLE-III PROPER MOTIONS

    SciTech Connect

    Poleski, Radosław; Gould, Andrew; Udalski, Andrzej; Szymański, M. K.; Soszyński, I.; Kubiak, M.; Pietrzyński, G.; Ulaczyk, K.; Wyrzykowski, Ł.

    2013-10-20

    The Galactic bulge shows a double red clump in sightlines at |b| ∼> 5° and –3° ∼< l ∼< 4°. This dump is interpreted as the signature of an X-shaped structure seen almost edge-on. We measure the proper motions of the stars belonging to the closer and the further arms of the X-shaped structure. The intrinsic kinematic properties of the two arms are found by incorporating information taken from the luminosity function. At b = –5°, we find that the proper motion difference between the two arms is a linear function of Galactic longitude for –0.°1 < l < 0.°5, which we interpret as a streaming motion of the stars within the X-shaped structure. A streaming motion was previously reported based on radial velocity data, not the proper motions. The proper motion difference in longitude is constant for –0.°8 < l < –0.°1, which provides an estimate of the bulge rotational speed of 87.9 ± 8.2 km s{sup –1} kpc{sup –1}.

  6. CdC-SF Catalogue.II: Application of its Proper Motions to Open Clusters

    NASA Astrophysics Data System (ADS)

    Vicente, B.; Garzón, F.

    We present an astrometric catalogue of positions and proper motions derived from the Carte du Ciel plates of the San Fernando zone, photographic material with a mean epoch 1901.4 with a limiting magnitude V˜15.Digitization has been made using a conventional flatbed scanner. Special techniques have been developed to handle the combination of plate material and the large distortion introduced by the scanner. A variety of post-scan corrections are shown to be necessary. The equatorial coordinates are on the ICRS system defined by Tycho-2. Comparison with the reference catalog indicates external errors of 0.;​​''2. The UCAC2 Catalogue was used as second-epoch positions to derive proper motions with a mean accuracy of 1.2 mas/year for the proper motions for well-measure stars. The usefulness of the resulting catalogue of proper motions is demonstrated by means of a proper-motion analysis of seven open clusters ASCC 30, BOCHUM 3, NGC 2215, NGC 2302, NGC 2311, NGC 2323 and NGC 2548, determining individual membership probabilities and characterizing the gross properties of each cluster.

  7. A maximum volume density estimator generalized over a proper motion-limited sample

    NASA Astrophysics Data System (ADS)

    Lam, Marco C.; Rowell, Nicholas; Hambly, Nigel C.

    2015-07-01

    The traditional Schmidt density estimator has been proven to be unbiased and effective in a magnitude-limited sample. Previously, efforts have been made to generalize it for populations with non-uniform density and proper motion-limited cases. This work shows that the then-good assumptions for a proper motion-limited sample are no longer sufficient to cope with modern data. Populations with larger differences in the kinematics as compared to the local standard of rest are most severely affected. We show that this systematic bias can be removed by treating the discovery fraction inseparable from the generalized maximum volume integrand. The treatment can be applied to any proper motion-limited sample with good knowledge of the kinematics. This work demonstrates the method through application to a mock catalogue of a white dwarf-only solar neighbourhood for various scenarios and compared against the traditional treatment using a survey with Pan-STARRS-like characteristics.

  8. The proper motion of HV2112: a TŻO candidate in the SMC

    NASA Astrophysics Data System (ADS)

    Worley, C. Clare; Irwin, Mike. J.; Tout, Christopher A.; Żytkow, Anna N.; Fraser, Morgan; Izzard, Robert G.

    2016-06-01

    The candidate Thorne-Żytkow object (TŻO), HV2112, is becoming a well-studied if enigmatic object. A key point of its candidacy as a TŻO is whether or not it resides in the Small Magellanic Cloud (SMC). HV2112 has detections in a series of photometric catalogues which have resulted in contradictory estimates of its proper motion and, therefore, its membership within the SMC. This letter seeks to resolve the issue of the SMC membership of HV2112 through a reanalysis of extant photometric data. We also demonstrate the difficulties and downfalls inherent in considering a range of catalogue proper motions. We conclude that the proper motion, and associated ancillary radial velocity, positional and photometric properties, are fully consistent with HV2112 being within the SMC and thus it remains a candidate TŻO.

  9. On the separations of common proper motion binaries containing white dwarfs

    NASA Technical Reports Server (NTRS)

    Oswalt, T. D.; Sion, E. M.

    1989-01-01

    It is expected, on the basis of proper motion and estimated colors, that over 500 known common proper motion binaries (CPMBs) contain at least one white dwarf (WD) component, usually paired with a late type main sequence (MS) star. This paper examines 210 probable MS + MS and 26 probable WD + MS pairs from the LDS catalog to determine whether significant orbital expansion occurred as a consequence of the post-MS mass loss expected to accompany the formation of WDs in the CPMBs. It was found that, in the WD + MS pairs, the physical separation is nearly twice that in the MS + MS pairs.

  10. Improved proper motion determinations for 15 open clusters based on the UCAC4 catalog

    NASA Astrophysics Data System (ADS)

    Kurtenkov, Alexander; Dimitrova, Nadezhda; Atanasov, Alexander; Aleksiev, Teodor D.

    2016-07-01

    The proper motions of 15 nearby (d > 1 kpc) open clusters (OCs) were recalculated using data from the UCAC4 catalog. Only evolved or main sequence stars inside a certain radius from the center of the cluster were used. The results significantly differ from the ones presented by Dias et al. (2014). This could be explained by a different approach in which we take the field star contamination into account. The present work aims to emphasize the importance of applying photometric criteria for the calculation of OC proper motions.

  11. Proper motions of 15 pulsars: a comparison between Bayesian and frequentist algorithms

    NASA Astrophysics Data System (ADS)

    Li, L.; Wang, N.; Yuan, J. P.; Wang, J. B.; Hobbs, G.; Lentati, L.; Manchester, R. N.

    2016-08-01

    We present proper motions for 15 pulsars which are observed regularly by the Nanshan 25-m radio telescope. Two methods, the frequentist method and the Bayesian method, are used and the results are compared. We demonstrate that the two methods can be applied to young pulsar data sets that exhibit large amounts of timing noise with steep spectral exponents and give consistent results. The measured positions also agree with very long baseline interferometric positions. Proper motions for four pulsars are obtained for the first time, and improved values are obtained for five pulsars.

  12. Proper motions of 15 pulsars: a comparison between Bayesian and frequentist algorithms

    NASA Astrophysics Data System (ADS)

    Li, L.; Wang, N.; Yuan, J. P.; Wang, J. B.; Hobbs, G.; Lentati, L.; Manchester, R. N.

    2016-08-01

    We present proper motions for 15 pulsars which are observed regularly by the Nanshan 25-m radio telescope. Two methods, the frequentist method (Coles et al.2011) and the Bayesian (Lentati et al. 2014) method, are used and the results are compared. We demonstrate that the two methods can be applied to young pulsar data sets that exhibit large amounts of timing noise with steep spectral exponents and give consistent results. The measured positions also agree with very-long-baseline interferometric positions. Proper motions for four pulsars are obtained for the first time, and improved values are obtained for five pulsars.

  13. A VERY HIGH PROPER MOTION STAR AND THE FIRST L DWARF IN THE KEPLER FIELD

    SciTech Connect

    Gizis, John E.; Troup, Nicholas W.; Burgasser, Adam J.

    2011-08-01

    We report two nearby high proper motion dwarfs of special interest identified using the Preliminary Data Release of the Wide-field Infrared Survey Explorer (WISE) and the Two Micron All Sky Survey. WISEP J191239.91-361516.4 has a motion of 2.1 arcsec yr{sup -1}. Photometry identifies it as a mid-M dwarf. WISEP J190648.47+401106.8 is a spectroscopically confirmed L1 dwarf in the Kepler Mission field with a motion of 0.48 arcsec yr{sup -1}. The estimated distance is 17 pc. Both lie at relatively low galactic latitudes and demonstrate the possibility of discovering proper motion stars independent of the historic photographic sky surveys.

  14. Ridge-spotting: A new test for Pacific absolute plate motion models

    NASA Astrophysics Data System (ADS)

    Wessel, Paul; Müller, R. Dietmar

    2016-06-01

    Relative plate motions provide high-resolution descriptions of motions of plates relative to other plates. Yet geodynamically, motions of plates relative to the mantle are required since such motions can be attributed to forces (e.g., slab pull and ridge push) acting upon the plates. Various reference frames have been proposed, such as the hot spot reference frame, to link plate motions to a mantle framework. Unfortunately, both accuracy and precision of absolute plate motion models lag behind those of relative plate motion models. Consequently, it is paramount to use relative plate motions in improving our understanding of absolute plate motions. A new technique called "ridge-spotting" combines absolute and relative plate motions and examines the viability of proposed absolute plate motion models. We test the method on six published Pacific absolute plate motions models, including fixed and moving hot spot models as well as a geodynamically derived model. Ridge-spotting reconstructs the Pacific-Farallon and Pacific-Antarctica ridge systems over the last 80 Myr. All six absolute plate motion models predict large amounts of northward migration and monotonic clockwise rotation for the Pacific-Farallon ridge. A geodynamic implication of our ridge migration predictions is that the suggestion that the Pacific-Farallon ridge may have been pinned by a large mantle upwelling is not supported. Unexpected or erratic ridge behaviors may be tied to limitations in the models themselves or (for Indo-Atlantic models) discrepancies in the plate circuits used to project models into the Pacific realm. Ridge-spotting is promising and will be extended to include more plates and other ocean basins.

  15. MEASURING THE UNDETECTABLE: PROPER MOTIONS AND PARALLAXES OF VERY FAINT SOURCES

    SciTech Connect

    Lang, Dustin; Hogg, David W.; Jester, Sebastian; Rix, Hans-Walter

    2009-05-15

    The near future of astrophysics involves many large solid-angle, multi-epoch, multiband imaging surveys. These surveys will, at their faint limits, have data on a large number of sources that are too faint to be detected at any individual epoch. Here, we show that it is possible to measure in multi-epoch data not only the fluxes and positions, but also the parallaxes and proper motions of sources that are too faint to be detected at any individual epoch. The method involves fitting a model of a moving point source simultaneously to all imaging, taking account of the noise and point-spread function (PSF) in each image. By this method it is possible to measure the proper motion of a point source with an uncertainty close to the minimum possible uncertainty given the information in the data, which is limited by the PSF, the distribution of observation times (epochs), and the total signal-to-noise in the combined data. We demonstrate our technique on multi-epoch Sloan Digital Sky Survey (SDSS) imaging of the SDSS Southern Stripe (SDSSSS). We show that with our new technique we can use proper motions to distinguish very red brown dwarfs from very high-redshift quasars in these SDSS data, for objects that are inaccessible to traditional techniques, and with better fidelity than by multiband imaging alone. We rediscover all 10 known brown dwarfs in our sample and present nine new candidate brown dwarfs, identified on the basis of significant proper motion.

  16. Fine structure in sunspots. II. Intensity variations and proper motions of umbral dots

    NASA Astrophysics Data System (ADS)

    Sobotka, Michal; Brandt, Peter N.; Simon, George W.

    1997-12-01

    Temporal intensity variations of umbral dots (UDs) and dark nuclei (DNs), and proper motions of UDs, were analyzed in a 4 1/2 hour time series of high resolution white light images of the umbra in a medium-size sunspot (NOAA 7519). The observations were made on 5 June 1993 at the Swedish Vacuum Solar Telescope, La Palma. An identification and tracking algorithm was applied to UDs observed in a destretched movie of 360 frames. In total, 662 UDs were tracked, and their intensities, positions, and proper motions were measured. Power spectra of temporal intensity variations of UDs and DNs were computed, and several typical periods were found. The histogram of time-averaged intensities of UDs has two maxima; the UDs belonging to the brighter part of the population are located mostly at or near the umbral-penumbral boundary. The number of UDs decreases with increasing magnitude of the proper motion velocity. Speeds of UDs are grouped at 100 and 400 m/s. The observed spatial distribution of UDs with different proper motion velocities is found to be in contradiction to the generally accepted idea of moving ``peripheral'' and stationary ``central'' UDs. Both ``fast'' and ``slow'' UDs are present in all parts of the umbra. Thus velocity does not appear to be a good criterion for separating UDs into ``peripheral'' and ``central'' ones.

  17. High Proper Motion Stars. III. Radial Velocities of 24 Late-Type Dwarfs

    NASA Astrophysics Data System (ADS)

    Dawson, P. C.; De Robertis, M. M.

    1998-11-01

    We report 27 radial velocity measurements for 24 stars, all with annual proper motions larger than 1". For 17 of these, no velocities have previously been published. We identify a few stars that may be spectroscopic binaries and a sdK star of spectacularly high space velocity.

  18. Two-stage model of African absolute motion during the last 30 million years

    NASA Astrophysics Data System (ADS)

    Pollitz, Fred F.

    1991-07-01

    The absolute motion of Africa (relative to the hotspots) for the past 30 My is modeled with two Euler vectors, with a change occurring at 6 Ma. Because of the high sensitivity of African absolute motions to errors in the absolute motions of the North America and Pacific plates, both the pre-6 Ma and post-6 Ma African absolute motions are determined simultaneously with North America and Pacific absolute motions for various epochs. Geologic data from the northern Atlantic and hotspot tracks from the African plate are used to augment previous data sets for the North America and Pacific plates. The difference between the pre-6 Ma and post-6 Ma absolute plate motions may be represented as a counterclockwise rotation about a pole at 48 °S, 84 °E, with angular velocity 0.085 °/My. This change is supported by geologic evidence along a large portion of the African plate boundary, including the Red Sea and Gulf of Aden spreading systems, the Alpine deformation zone, and the central and southern mid-Atlantic Ridge. Although the change is modeled as one abrupt transition at 6 Ma, it was most likely a gradual change spanning the period 8-4 Ma. As a likely mechanism for the change, we favor strong asthenospheric return flow from the Afar hotspot towards the southwest; this could produce the uniform southwesterly shift in absolute motion which we have inferred as well as provide a mechanism for the opening of the East African Rift. Comparing the absolute motions of the North America and Pacific plates with earlier estimates, the pole positions are revised by up to 5° and the angular velocities are decreased by 10-20%.

  19. A Proper Motion Survey Using the First Sky Pass of NEOWISE-reactivation Data

    NASA Astrophysics Data System (ADS)

    Schneider, Adam C.; Greco, Jennifer; Cushing, Michael C.; Kirkpatrick, J. Davy; Mainzer, Amy; Gelino, Christopher R.; Fajardo-Acosta, Sergio B.; Bauer, James

    2016-02-01

    The Wide-field Infrared Survey Explorer (WISE) was reactivated in 2013 December (NEOWISE) to search for potentially hazardous near-Earth objects. We have conducted a survey using the first sky pass of NEOWISE data and the AllWISE catalog to identify nearby stars and brown dwarfs with large proper motions ({μ }{{total}} ≳ 250 mas yr-1). A total of 20,548 high proper motion objects were identified, 1006 of which are new discoveries. This survey has uncovered a significantly larger sample of fainter objects (W2 ≳ 13 mag) than the previous WISE motion surveys of Luhman and Kirkpatrick et al. Many of these objects are predicted to be new L and T dwarfs based on near- and mid-infrared colors. Using estimated spectral types along with distance estimates, we have identified several objects that likely belong to the nearby solar neighborhood (d < 25 pc). We have followed up 19 of these new discoveries with near-infrared or optical spectroscopy, focusing on potentially nearby objects, objects with the latest predicted spectral types, and potential late-type subdwarfs. This subset includes six M dwarfs, five of which are likely subdwarfs, as well as eight L dwarfs and five T dwarfs, many of which have blue near-infrared colors. As an additional supplement, we provide 2MASS and AllWISE positions and photometry for every object found in our search, as well as 2MASS/AllWISE calculated proper motions.

  20. VLBI FOR GRAVITY PROBE B. V. PROPER MOTION AND PARALLAX OF THE GUIDE STAR, IM PEGASI

    SciTech Connect

    Ratner, M. I.; Lebach, D. E.; Shapiro, I. I.; Bartel, N.; Bietenholz, M. F.; Ransom, R. R.; Lestrade, J.-F.

    2012-07-01

    We present the principal astrometric results of the very long baseline interferometry (VLBI) program undertaken in support of the Gravity Probe B (GP-B) relativity mission. VLBI observations of the GP-B guide star, the RS CVn binary IM Pegasi (HR 8703), yielded positions at 35 epochs between 1997 and 2005. We discuss the statistical assumptions behind these results and our methods for estimating the systematic errors. We find the proper motion of IM Peg in an extragalactic reference frame closely related to the International Celestial Reference Frame 2 (ICRF2) to be -20.83 {+-} 0.03 {+-} 0.09 mas yr{sup -1} in right ascension and -27.27 {+-} 0.03 {+-} 0.09 mas yr{sup -1} in declination. For each component, the first uncertainty is the statistical standard error and the second is the total standard error (SE) including plausible systematic errors. We also obtain a parallax of 10.37 {+-} 0.07 mas (distance: 96.4 {+-} 0.7 pc), for which there is no evidence of any significant contribution of systematic error. Our parameter estimates for the {approx}25 day period orbital motion of the stellar radio emission have SEs corresponding to {approx}0.10 mas on the sky in each coordinate. The total SE of our estimate of IM Peg's proper motion is {approx}30% smaller than the accuracy goal set by the GP-B project before launch: 0.14 mas yr{sup -1} for each coordinate of IM Peg's proper motion. Our results ensure that the uncertainty in IM Peg's proper motion makes only a very small contribution to the uncertainty of the GP-B relativity tests.

  1. Distance and proper motion measurement of water masers in sharpless 269 IRS 2w

    SciTech Connect

    Asaki, Y.; Imai, H.; Sobolev, A. M.; Parfenov, S. Yu. E-mail: hiroimai@sci.kagoshima-u.ac.jp E-mail: Sergey.Parfenov@urfu.ru

    2014-05-20

    We present astrometric analysis of archival data of water masers in the star-forming region Sharpless 269 (S269) IRS 2w, observed with the VLBI Exploration of Radio Astrometry. An annual parallax of one of the bright maser features in this region was previously reported to be 0.189 ± 0.008 milliarcsecond (mas) using part of the same archival data as we used. However, we found that this maser feature is not the best to represent the annual parallax to S269 IRS 2w because the morphology is remarkably elongated in the east-west direction. For this study we have selected another maser feature showing simpler morphology. This makes the new annual parallax estimate more credible. Our newly obtained annual parallax is 0.247 ± 0.034 mas, corresponding to 4.05{sub −0.49}{sup +0.65} kpc. This value is well consistent with the 3.7-3.8 kpc obtained using the kinematic distance estimates and photometric distance modulus. We considered two hypotheses for the water-maser spatial distribution, a bipolar outflow and an expanding ring, in a kinematic model fitting analysis with a radially expanding flow. At this stage, any conclusions about the systemic proper motion could not be drawn from the kinematic analysis. Alternatively, we evaluated the mean proper motion to be (0.39 ± 0.92, –1.27 ± 0.90) mas yr{sup –1} eastward and northward, respectively, from the obtained proper motions of the detected water-maser features. The newly obtained annual parallax and mean proper motion give the peculiar motion of S269 IRS 2w to be (U {sub s}, V {sub s}, W {sub s}) of (8 ± 6, –21 ± 17, 1 ± 18) km s{sup –1}.

  2. Proper motions and membership probabilities of stars in the region of globular cluster NGC 6366

    NASA Astrophysics Data System (ADS)

    Sariya, Devesh P.; Yadav, R. K. S.

    2015-12-01

    Context. NGC 6366 is a metal-rich globular cluster that is relatively unstudied. It is a kinematically interesting cluster, reported as belonging to the slowly rotating halo system, which is unusual given its metallicity and spatial location in the Galaxy. Aims: The purpose of this research is to determine the relative proper motion and membership probability of the stars in the region of globular cluster NGC 6366. To target cluster members reliably during spectroscopic surveys without including field stars, a good proper motion and membership probability catalogue of NGC 6366 is needed. Methods: To derive relative proper motions, the archival data from the Wide Field Imager mounted on the ESO 2.2 m telescope have been reduced using a high precision astrometric software. The images used are in the B,V, and I photometric bands with an epoch gap of ~3.2 yr. The calibrated BVI magnitudes have been determined using recent data for secondary standard stars. Results: We determined relative proper motions and cluster membership probabilities for 2530 stars in the field of globular cluster NGC 6366. The median proper motion rms errors for stars brighter than V ~ 18 mag is ~2 mas yr-1, which gradually increases to ~5 mas yr-1 for stars having magnitudes V ~ 20 mag. Based on the membership catalogue, we checked the membership status of the X-ray sources and variable stars of NGC 6366 mentioned in the literature. We also provide the astronomical community with an electronic catalogue that includes B, V, and I magnitudes; relative proper motions; and membership probabilities of the stars in the region of NGC 6366. Based on observations with the MPG/ESO 2.2 m and ESO/VLT telescopes, located at La Silla and Paranal Observatory, Chile, under DDT programs 164.O-0561(F), 71.D-0220(A) and the archive material.Full Table 4 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/584/A59

  3. A FIRST MEASUREMENT OF THE PROPER MOTION OF THE LEO II DWARF SPHEROIDAL GALAXY

    SciTech Connect

    Lepine, Sebastien; Koch, Andreas; Rich, R. Michael; Kuijken, Konrad

    2011-11-10

    We use 14 year baseline images obtained with the Wide Field and Planetary Camera 2 on board the Hubble Space Telescope (HST) to derive a proper motion for one of the Milky Way's most distant dwarf spheroidal companions, Leo II, relative to an extragalactic background reference frame. Astrometric measurements are performed in the effective point-spread function formalism using our own developed code. An astrometric reference grid is defined using 3224 stars that are members of Leo II and brighter than a magnitude of 25 in the F814W band. We identify 17 compact extragalactic sources, for which we measure a systemic proper motion relative to this stellar reference grid. We derive a proper motion [{mu}{sub {alpha},{mu}{delta}}] = [+104 {+-}113,-33 {+-} 151] {mu}as yr{sup -1} for Leo II in the heliocentric reference frame. Though marginally detected, the proper motion yields constraints on the orbit of Leo II. Given a distance of d {approx_equal} 230 kpc and a heliocentric radial velocity v{sub r} = +79 km s{sup -1}, and after subtraction of the solar motion, our measurement indicates a total orbital motion v{sub G} = 266.1 {+-} 128.7 km s{sup -1} in the Galactocentric reference frame, with a radial component v{sub r{sub G}}=21.5{+-}4.3 km s{sup -1} and tangential component v{sub t{sub G}} = 265.2 {+-} 129.4 km s{sup -1}. The small radial component indicates that Leo II either has a low-eccentricity orbit or is currently close to perigalacticon or apogalacticon distance. We see evidence for systematic errors in the astrometry of the extragalactic sources which, while close to being point sources, are slightly resolved in the HST images. We argue that more extensive observations at later epochs will be necessary to better constrain the proper motion of Leo II. We provide a detailed catalog of the stellar and extragalactic sources identified in the HST data which should provide a solid early-epoch reference for future astrometric measurements.

  4. Globular Cluster Membership Probabilities from All-Sky Proper Motion Catalogs

    NASA Astrophysics Data System (ADS)

    Rees, Richard F.; Cudworth, Kyle M.

    2014-06-01

    Recent all-sky catalogs such as UCAC4 (Zacharias et al. 2013, AJ, 145:44) and PPMXL (Roeser et al. 2010, AJ, 139, 2440) contain proper motions with errors of 1-10 mas/yr. This precision is sufficient to determine membership probabilities for stars in the fields of globular clusters if the cluster motion is reasonably different from the field star motion. We use membership probabilities for stars in the field of the globular cluster NGC 6397 derived from very high precision relative proper motions 0.2 mas/yr errors) from long-focus plates to test membership probabilities derived from UCAC4 and PPMXL motions. We also explore the use of UCAC4 and PPMXL to search for cluster members beyond the small field of the long-focus plates.This publication makes use of data products from the Two Micron All Sky Survey, which is a joint project of the University of Massachusetts and the Infrared Processing and Analysis Center/California Institute of Technology, funded by NASA and the NSF. This research has made use of the VizieR catalogue access tool, CDS, Strasbourg, France. This research has been partially supported by the NSF.

  5. Discovery of High Proper-Motion Ancient White Dwarfs: Nearby Massive Compact Halo Objects?

    PubMed

    Ibata; Irwin; Bienaymé; Scholz; Guibert

    2000-03-20

    We present the discovery and spectroscopic identification of two very high proper-motion ancient white dwarf stars, found in a systematic proper-motion survey. Their kinematics and apparent magnitude clearly indicate that they are halo members, while their optical spectra are almost identical to the recently identified cool halo white dwarf WD 0346+246. Canonical stellar halo models predict a white dwarf volume density that is 2 orders of magnitude less than the rho approximately 7x10-4 M middle dot in circle pc-3 inferred from this survey. With the caveat that the sample size is very small, it appears that a significant fraction, approximately 10%, of the local dark matter halo is in the form of very old, cool, white dwarfs. PMID:10702128

  6. Four years experience in APMS star plate processing - Results and future plans. [Automated Proper Motion Study

    NASA Technical Reports Server (NTRS)

    Newcomb, J. S.

    1975-01-01

    The present paper describes an automated system for measuring stellar proper motions on the basis of information contained in photographic plates. In this system, the images on a star plate are digitized by a scanning microdensitometer using light from a He-Ne gas laser, and a special-purpose computer arranges the measurements in computer-compatible form on magnetic tape. The scanning and image-reconstruction processes are briefly outlined, and the image-evaluation techniques are discussed. It is shown that the present system has been especially successful in measuring the proper motions of low-luminosity stars, including 119 stars with less than 1/10,000 of the solar bolometric luminosity. Plans for measurements of high-density Milky Way star plates are noted.

  7. Optical BVRI photometry of common proper motion F/G/K+M wide separation binaries

    SciTech Connect

    Li, Ting; Marshall, Jennifer L.; Williams, Patrick; Chavez, Joy; Lépine, Sébastien

    2014-10-01

    We present optical (BVRI) photometric measurements of a sample of 76 common proper motion wide separation main-sequence binary pairs. The pairs are composed of a F-, G-, or K-type primary star and an M-type secondary. The sample is selected from the revised NLTT catalog and the LSPM catalog. The photometry is generally precise to 0.03 mag in all bands. We separate our sample into two groups, dwarf candidates and subdwarf candidates, using the reduced proper motion diagram constructed with our improved photometry. The M subdwarf candidates in general have larger V – R colors than the M dwarf candidates at a given V – I color. This is consistent with an average metallicity difference between the two groups, as predicted by the PHOENIX/BT-Settl models. The improved photometry will be used as input into a technique to determine the metallicities of the M-type stars.

  8. Searching for Proper-Motion Brown Dwarfs in the Mid-IR

    NASA Astrophysics Data System (ADS)

    Li, Zequn; Ashby, Matthew; Hora, Joseph L.

    2015-01-01

    We have carried out a sensitive search for infrared proper-motion sources in the 10 square degree Spitzer/IRAC Bootes field with imaging that covers a ten-year timespan. With the latest epoch, from the Decadal IRAC Survey of Bootes (DIBS), a Cycle 10 Spitzer program, we have identified more than 2000 4.5 micron sources with proper motions in excess of 3-sigma significance, between 0.05 and 0.7 arcsec/yr. Based on the extensive multiband photometry available for our sources, we estimate rough types and distances. A fraction of these dim, nearby sources are brown dwarfs--objects which are typically very difficult to detect at visible wavelengths because they are optically dim. This work is supported in part by the NSF REU and DOD ASSURE programs under NSF grant no. 1262851 and by the Smithsonian Institution.

  9. XO-2b: A Transiting Hot Jupiter in a Metal-rich Common Proper Motion Binary

    NASA Astrophysics Data System (ADS)

    Burke, Christopher J.; McCullough, P. R.; Valenti, J. A.; Summers, F. J.; Stys, J. E.; Johns-Krull, C. M.; Janes, K. A.; Heasley, J. N.; Bissinger, R.; Fleenor, M.; Foote, C. N.; Garcia-Melendo, E.; Gary, B. L.; Howell, P. J.; Mallia, F.; Masi, G.; Vanmunster, T.

    2007-05-01

    XO-2b, the second transiting extrasolar planet from the XO Project (McCullough et al. 2005), is approximately Jupiter-size and 0.6 Jupiter-mass with an orbital period of 2.6 days. The stellar host, XO-2, is a V=11.2, early K dwarf which is metal rich, [Fe/H]=+0.44. XO-2 has a high proper motion, 157 mas/yr, and has a common proper motion stellar companion with half arcmin separation. The two stars are nearly identical twins, with very similar spectra and apparent magnitudes. The global network of amateur and professional astronomers organized by the XO project confirmed the XO-2b transit light curve two days after being notified that it was a high-priority candidate, and radial velocities confirmed its planetary mass eight days after that.

  10. Proper motion of the Draco dwarf galaxy based on Hubble space telescope imaging

    SciTech Connect

    Pryor, Carlton; Piatek, Slawomir; Olszewski, Edward W. E-mail: piatek@physics.rutgers.edu

    2015-02-01

    We have measured the proper motion of the Draco dwarf galaxy using images at two epochs with a time baseline of about two years taken with the Hubble Space Telescope Advanced Camera for Surveys. Wide Field Channels 1 and 2 provide two adjacent fields, each containing a known QSO. The zero point for the proper motion is determined using both background galaxies and the QSOs and the two methods produce consistent measurements within each field. Averaging the results from the two fields gives a proper motion in the equatorial coordinate system of (μ{sub α},μ{sub δ})=(17.7±6.3,−22.1±6.3) mas century{sup −1} and in the Galactic coordinate system of (μ{sub ℓ},μ{sub b})=(−23.1±6.3,−16.3±6.3) mas century{sup −1}. Removing the contributions of the motion of the Sun and of the LSR to the measured proper motion yields a Galactic rest-frame proper motion of (μ{sub α}{sup Grf},μ{sub δ}{sup Grf})=(51.4±6.3,−18.7±6.3) mas century{sup −1} and (μ{sub ℓ}{sup Grf},μ{sub b}{sup Grf})=(−21.8±6.3,−50.1±6.3) mas century{sup −1}. The implied space velocity with respect to the Galactic center is (Π,Θ,Z)=(27±14,89±25,−212±20) km s{sup −1}. This velocity implies that the orbital inclination is 70{sup ∘}, with a 95% confidence interval of (59{sup ∘},80{sup ∘}), and that the plane of the orbit is consistent with that of the vast polar structure (VPOS) of Galactic satellite galaxies.

  11. X-ray Proper Motions and Shock Speeds along the Northwest Rim of SN1006

    NASA Technical Reports Server (NTRS)

    Katsuda, Satoru; Long, Knox S.; Petre, Robert; Reynolds, Stephen P.; Williams, Brian J.; Winkler, P. Frank

    2012-01-01

    We report the results of an X-ray proper motion measurement for the NW rim of SN 1006, carried out by comparing Chandra observations from 2001 and 2012. The NW limb has predominantly thermal X-ray emission, and it is the only location in SN 1006 with signi cant optical emission: a thin, Balmer-dominated lament. For most of the NW rim, the proper motion is approximately equal to 0.30"yr(exp -1), essentially the same as has been measured from the H alpha lament. Isolated regions of the NW limb are dominated by nonthermal emission, and here the proper motion is much higher, 0:49"yr(exp -1), close to the value measured in X-rays along the much brighter NE limb, where the X-rays are overwhelmingly nonthermal. At the 2.2 kpc distance to SN 1006, the proper motions imply shock velocities of approximately 3000 kms(exp -1) and approximately 5000 kms(exp -1) in the thermal and nonthermal regions, respectively. A lower velocity behind the H alpha filament is consistent with the picture that SN 1006 is encountering denser gas in the NW, as is also suggested by its overall morphology. In the thermally-dominated portion of the X-ray shell, we also see an o set in the radial profiles at different energies; the 0.5-0.6 keV peak dominated by O VII is closer to the shock front than that of the 0.8-3 keV emission|due to the longer times for heavier elements to reach ionization states where they produce strong X-ray emission.

  12. X-RAY PROPER MOTIONS AND SHOCK SPEEDS ALONG THE NORTHWEST RIM OF SN 1006

    SciTech Connect

    Katsuda, Satoru; Long, Knox S.; Williams, Brian J.; Petre, Robert; Reynolds, Stephen P.; Winkler, P. Frank E-mail: long@stsci.edu E-mail: reynolds@ncsu.edu

    2013-02-15

    We report the results of an X-ray proper-motion measurement for the NW rim of SN 1006, carried out by comparing Chandra observations from 2001 to 2012. The NW limb has predominantly thermal X-ray emission, and it is the only location in SN 1006 with significant optical emission: a thin, Balmer-dominated filament. For most of the NW rim, the proper motion is Almost-Equal-To 0.''30 yr{sup -1}, essentially the same as has been measured from the H{alpha} filament. Isolated regions of the NW limb are dominated by nonthermal emission, and here the proper motion is much higher, 0.''49 yr{sup -1}, close to the value measured in X-rays along the much brighter NE limb, where the X-rays are overwhelmingly nonthermal. At the 2.2 kpc distance to SN 1006, the proper motions imply shock velocities of {approx}3000 km s{sup -1} and {approx}5000 km s{sup -1} in the thermal and nonthermal regions, respectively. A lower velocity behind the H{alpha} filament is consistent with the picture that SN 1006 is encountering denser gas in the NW, as is also suggested by its overall morphology. In the thermally dominated portion of the X-ray shell, we also see an offset in the radial profiles at different energies; the 0.5-0.6 keV peak dominated by O VII is closer to the shock front than that of the 0.8-3 keV emission-due to the longer times for heavier elements to reach ionization states where they produce strong X-ray emission.

  13. WATER MASERS IN THE ANDROMEDA GALAXY: THE FIRST STEP TOWARD PROPER MOTION

    SciTech Connect

    Darling, Jeremy

    2011-05-01

    We have detected and confirmed five water maser complexes in the Andromeda Galaxy (M31) using the Green Bank Telescope. These masers will provide the high brightness temperature point sources needed for proper motion studies of M31, enabling measurement of its full three-dimensional velocity vector and its geometric distance via proper rotation. The motion of M31 is the keystone of Local Group dynamics and a gateway to the dark matter profiles of galaxies in general. Our survey for water masers selected 206 luminous compact 24 {mu}m emitting regions in M31 and was sensitive enough to detect any maser useful for {approx}10 {mu}as yr{sup -1} astrometry. The newly discovered masers span the isotropic luminosity range (0.3-1.9) x 10{sup -3} L{sub sun} in single spectral components and are analogous to luminous Galactic masers. The masers are distributed around the molecular ring, including locations close to the major and minor axes, which is nearly ideal for proper motion studies. We find no correlation between 24 {mu}m luminosity and water maser luminosity, suggesting that while water masers arise in star-forming regions, the nonlinear amplification pathways and beamed nature of the water masers means that they are not predictable based on IR luminosity alone. This suggests that there are additional bright masers to be found in M31. We predict that the geometric distance and systemic proper motion of M31 can be measured in 2-3 years with current facilities. A 'moving cluster' observation of diverging masers as M31 approaches the Galaxy may be possible in the long term.

  14. Measuring the proper motions of the Large and Small Magellanic Clouds

    NASA Astrophysics Data System (ADS)

    Ellingsen, Simon; Macquart, Jean-Pierre; Bignall, Hayley; Breen, Shari; Reynolds, Cormac; Imai, Hiroshi; Keller, Stefan; Bekki, Kenji; Krishnan, Vasaant; Cioni, Maria-Rosa

    2013-10-01

    Interactions between galaxies are known to play a key role in their evolution throughout cosmic history. Studies of past and current interactions between Local Group galaxies provide us with a unique opportunity to investigate the key factors and effects of such interactions at high resolution and sensitivity. Our understanding of the interaction of the Large and Small Magellanic Clouds (LMC & SMC) with each other and with the Milky Way (MW) have changed dramatically in the last decade due to the determination of the proper motions of the LMC and SMC from optical studies. The derived proper motions predict a history of interaction for the Clouds that is at odds with the leading and trailing arms of Magellanic Stream gas. This proposal is a companion to an LBA project to measure the proper motions of both the Large and Small Magellanic Clouds. Observations to measure the flux density of the potential maser targets a few weeks prior to an LBA observation will enable us to tailor the observing strategy to maximise the observational sensitivity and hence the astrometric accuracy.

  15. Measuring the proper motions of the Large and Small Magellanic Clouds

    NASA Astrophysics Data System (ADS)

    Ellingsen, Simon; Macquart, Jean-Pierre; Bignall, Hayley; Breen, Shari; Reynolds, Cormac; Imai, Hiroshi; Keller, Stefan; Bekki, Kenji; Krishnan, Vasaant; Cioni, Maria-Rosa

    2013-04-01

    Interactions between galaxies are known to play a key role in their evolution throughout cosmic history. Studies of past and current interactions between Local Group galaxies provide us with a unique opportunity to investigate the key factors and effects of such interactions at high resolution and sensitivity. Our understanding of the interaction of the Large and Small Magellanic Clouds (LMC & SMC) with each other and with the Milky Way (MW) have changed dramatically in the last decade due to the determination of the proper motions of the LMC and SMC from optical studies. The derived proper motions predict a history of interaction for the Clouds that is at odds with the leading and trailing arms of Magellanic Stream gas. This proposal is a companion to an LBA project to measure the proper motions of both the Large and Small Magellanic Clouds. Observations to measure the flux density of the potential maser targets a few weeks prior to an LBA observation will enable us to tailor the observing strategy to maximise the observational sensitivity and hence the astrometric accuracy.

  16. Measuring the proper motions of the Large and Small Magellanic Clouds

    NASA Astrophysics Data System (ADS)

    Ellingsen, Simon; Macquart, Jean-Pierre; Bignall, Hayley; Beasley, Tony; Breen, Shari; Reynolds, Cormac; Imai, Hiroshi; Keller, Stefan; Bekki, Kenji; Krishnan, Vasaant; Cioni, Maria-Rosa

    2014-04-01

    Interactions between galaxies are known to play a key role in their evolution throughout cosmic history. Studies of past and current interactions between Local Group galaxies provide us with a unique opportunity to investigate the key factors and effects of such interactions at high resolution and sensitivity. Our understanding of the interaction of the Large and Small Magellanic Clouds (LMC & SMC) with each other and with the Milky Way (MW) have changed dramatically in the last decade due to the determination of the proper motions of the LMC and SMC from optical studies. The derived proper motions predict a history of interaction for the Clouds that is at odds with the leading and trailing arms of Magellanic Stream gas. This proposal is a companion to an LBA project to measure the proper motions of both the Large and Small Magellanic Clouds. Observations to measure the flux density of the potential maser targets a few weeks prior to an LBA observation will enable us to tailor the observing strategy to maximise the observational sensitivity and hence the astrometric accuracy.

  17. On the Connection of the Apparent Proper Motion and the VLBI Structure of Compact Radio Sources

    NASA Astrophysics Data System (ADS)

    Moór, A.; Frey, S.; Lambert, S. B.; Titov, O. A.; Bakos, J.

    2011-06-01

    Many of the compact extragalactic radio sources that are used as fiducial points to define the celestial reference frame are known to have proper motions detectable with long-term geodetic/astrometric very long baseline interferometry (VLBI) measurements. These changes can be as high as several hundred microarcseconds per year for certain objects. When imaged with VLBI at milliarcsecond (mas) angular resolution, these sources (radio-loud active galactic nuclei) typically show structures dominated by a compact, often unresolved "core" and a one-sided "jet." The positional instability of compact radio sources is believed to be connected with changes in their brightness distribution structure. For the first time, we test this assumption in a statistical sense on a large sample rather than on only individual objects. We investigate a sample of 62 radio sources for which reliable long-term time series of astrometric positions as well as detailed 8 GHz VLBI brightness distribution models are available. We compare the characteristic direction of their extended jet structure and the direction of their apparent proper motion. We present our data and analysis method, and conclude that there is indeed a correlation between the two characteristic directions. However, there are cases where the ~1-10 mas scale VLBI jet directions are significantly misaligned with respect to the apparent proper motion direction.

  18. Characterization of high proper motion objects from the wide-field infrared survey explorer

    SciTech Connect

    Luhman, K. L.; Sheppard, Scott S.

    2014-06-01

    We present an analysis of high proper motion objects that we have found in a recent study and in this work with multi-epoch astrometry from the Wide-field Infrared Survey Explorer (WISE). Using photometry and proper motions from the Two Micron All-Sky Survey and WISE, we have identified the members of this sample that are likely to be late-type, nearby, or metal-poor. We have performed optical and near-infrared spectroscopy on 41 objects, from which we measure spectral types that range from M4-T2.5. This sample includes 11 blue L dwarfs and 5 subdwarfs; the latter were also classified as such in the recent study by Kirkpatrick and coworkers. Based on their spectral types and photometry, several of our spectroscopic targets may have distances of <20 pc with the closest at ∼12 pc. The tangential velocities implied by the spectrophotometric distances and proper motions indicate that four of the five subdwarfs are probably members of the Galactic halo while several other objects, including the early-T dwarf WISE J210529.08–623558.7, may belong to the thick disk.

  19. Recoil of the Stellar Remnant from the Puppis A Supernova: Proper-Motion Measurement from Chandra

    NASA Technical Reports Server (NTRS)

    Petre, Robert; Winkler, P. F.

    2006-01-01

    A sequence of three Chandra X-ray Observatory High Resolution Camera images taken over a span of five years reveals arc-second-scale displacement of RX-J0822--4300, the stellar remnant near the center of the Puppis A supernova remnant. We measure its proper motion to be 0.16+/-0.02 arcsec/yr toward the west-southwest. At a distance of 2 kpc, this corresponds to a transverse space velocity of approx. 1500 km/s. This is the first case of a compact X-ray source with a directly measured proper motion. The space velocity is consistent with the explosion center inferred from proper motions of the oxygen-rich optical filaments, and confirms the idea that Puppis A resulted from an asymmetric explosion accompanied by a kick that imparted on the order of 3 x 10(exp 49) ergs of kinetic energy (some 3 percent of the supernova kinetic energy) to the stellar remnant. We will summarize this measurement and discuss possible mechanisms for producing such a violent kick. This research has been supported by NASA grant G04-5062X.

  20. Proper motions of radiative knots in simulations of stellar jets. An alternative to pulsating inflow conditions

    NASA Astrophysics Data System (ADS)

    Rubini, F.; Lorusso, S.; Del Zanna, L.; Bacciotti, F.

    2007-09-01

    Aims:Elongated jets from young stellar objects typically present a nodular structure, formed by a chain of bright knots of enhanced emission with individual proper motions. Though it is generally accepted that internal shocks play an important role in the formation and dynamics of such structures, their precise origin and the mechanisms behind the observed proper motions is still a matter of debate. Our goal is to study numerically the origin, dynamics, and emission properties of such knots. Methods: Axisymmetric simulations are performed with a shock-capturing code for gas dynamics, allowing for molecular, atomic, and ionized hydrogen in non-equilibrium concentrations subject to ionization/recombination processes. Radiative losses in [S ii] lines are computed, and the resulting synthetic emission maps are compared with observations. Results: We show that a pattern of regularly spaced internal oblique shocks, characterized by individual proper motions, is generated by the pressure gradient between the propagating jet and the time variable external cocoon. In the case of under-expanded, light jets the resulting emission knots are found to move downstream with the jet flow, with increasing velocity and decaying brightness toward the leading bow shock. This suggests that the basic properties of the knots observed in stellar jets can be reproduced even without invoking ad hoc pulsating conditions at the jet inlet, though an interplay between the two scenarios is certainly possible.

  1. XO-2b: Transiting Hot Jupiter in a Metal-rich Common Proper Motion Binary

    NASA Astrophysics Data System (ADS)

    Burke, Christopher J.; McCullough, P. R.; Valenti, Jeff A.; Johns-Krull, Christopher M.; Janes, Kenneth A.; Heasley, J. N.; Summers, F. J.; Stys, J. E.; Bissinger, R.; Fleenor, Michael L.; Foote, Cindy N.; García-Melendo, Enrique; Gary, Bruce L.; Howell, P. J.; Mallia, F.; Masi, G.; Taylor, B.; Vanmunster, T.

    2007-12-01

    We report on a V=11.2 early K dwarf, XO-2 (GSC 03413-00005), that hosts a Rp=0.98+/-0.030.01 RJ, Mp=0.57+/-0.06 MJ transiting extrasolar planet, XO-2b, with an orbital period of 2.615857+/-0.000005 days. XO-2 has high metallicity, [Fe/H]=0.45+/-0.02, high proper motion, μtot=157 mas yr-1, and a common proper motion stellar companion with 31" separation. The two stars are nearly identical twins, with very similar spectra and apparent magnitudes. Due to the high metallicity, these early K dwarf stars have a mass and radius close to solar, M*=0.98+/-0.02 Msolar and R*=0.97+/-0.020.01 Rsolar. The high proper motion of XO-2 results from an eccentric orbit (Galactic pericenter, Rper<4 kpc) well confined to the Galactic disk (Zmax~100 pc). In addition, the phase-space position of XO-2 is near the Hercules dynamical stream, which points to an origin of XO-2 in the metal-rich, inner thin disk and subsequent dynamical scattering into the solar neighborhood. We describe an efficient Markov chain Monte Carlo algorithm for calculating the Bayesian posterior probability of the system parameters from a transit light curve.

  2. Improvement of Accuracy of Proper Motions of Hipparcos Catalogue Stars Using Optical Latitude Observations

    NASA Astrophysics Data System (ADS)

    Damljanovic, G.

    2009-09-01

    Commission 19 (Earth Rotation) of the International Astronomical Union (IAU) established the Working Group on Earth Rotation in the Hipparcos Reference Frame (WG ERHRF) in 1995 to collect the optical observations of latitude and universal time variations, made during 1899.7 -- 1992.0 in line with the Earth orientation programmes (to derive Earth Orientation Parameters -- EOP), with Dr. Jan Vondrák (Astronomical Institute of Academy of Sciences of the Czech Republic, Prague) as the head of WG ERHRF. We participated in this international project using Belgrade Visual Zenith -- Telescope (BLZ) latitude data for the period 1949.0 -- 1986.0, after a new reduction of BLZ data made in my MSc thesis, finished in 1997 at the Faculty of Mathematics of University of Belgrade. Dr. Vondrák collected 4.4 million optical observations of latitude/universal time variations made at 33 observatories. The data were used for the EOP investigations, Hipparcos satellite Catalogue -- radio sources connection, etc. Nowadays, it is customary to correct the positions and proper motions of stars of Hipparcos Catalogue (as an optical reference frame) using ground -- based observations of some Hipparcos stars. In this PhD thesis we use the latitude observations made with several types of classical astrometric instruments: visual (ZT) and floating zenith -- telescope (FZT), visual zenith tube (VZT) and photographic zenith tube (PZT); 26 different instruments located at many observatories all over the world (used in the programs of monitoring the Earth orientation during the 20th century). We received the data from Dr. Vondrák via private communication. The observatories and instruments are: International Latitude Service -- ILS (Carloforte -- CA ZT, Cincinnati -- CI ZT, Gaithersburg -- GT ZT, Kitab -- KZ ZT, Mizusawa -- MZZ ZT, Tschardjui -- TS ZT and Ukiah -- UK ZT), Belgrade (BLZ ZT), Blagoveschtschensk (BK ZT), Irkutsk (IRZ ZT), Poltava (POL ZT), Pulkovo (PU and PUZ ZT), Varsovie (VJZ ZT

  3. 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

  4. INVESTIGATION OF THE ERRORS IN SLOAN DIGITAL SKY SURVEY PROPER-MOTION MEASUREMENTS USING SAMPLES OF QUASARS

    SciTech Connect

    Dong Ruobing; Gunn, James; Knapp, Gillian; Rockosi, Constance

    2011-10-15

    We investigate in detail the probability distribution function (pdf) of the proper-motion measurement errors in the SDSS+USNO-B proper-motion catalog of Munn et al. using clean quasar samples. The pdf of the errors is well represented by a Gaussian core with extended wings, plus a very small fraction (<0.1%) of 'outliers'. We find that while formally the pdf could be well fit by a five-parameter fitting function, for many purposes it is also adequate to represent the pdf with a one-parameter approximation to this function. We apply this pdf to the calculation of the confidence intervals on the true proper motion for an SDSS+USNO-B proper-motion measurement, and discuss several scientific applications of the SDSS proper-motion catalog. Our results have various applications in studies of the galactic structure and stellar kinematics. Specifically, they are crucial for searching hyper-velocity stars in the Galaxy.

  5. Is an absolute level of cortical beta suppression required for proper movement? Magnetoencephalographic evidence from healthy aging.

    PubMed

    Heinrichs-Graham, Elizabeth; Wilson, Tony W

    2016-07-01

    Previous research has connected a specific pattern of beta oscillatory activity to proper motor execution, but no study to date has directly examined how resting beta levels affect motor-related beta oscillatory activity in the motor cortex. Understanding this relationship is imperative to determining the basic mechanisms of motor control, as well as the impact of pathological beta oscillations on movement execution. In the current study, we used magnetoencephalography (MEG) and a complex movement paradigm to quantify resting beta activity and movement-related beta oscillations in the context of healthy aging. We chose healthy aging as a model because preliminary evidence suggests that beta activity is elevated in older adults, and thus by examining older and younger adults we were able to naturally vary resting beta levels. To this end, healthy younger and older participants were recorded during motor performance and at rest. Using beamforming, we imaged the peri-movement beta event-related desynchronization (ERD) and extracted virtual sensors from the peak voxels, which enabled absolute and relative beta power to be assessed. Interestingly, absolute beta power during the pre-movement baseline was much stronger in older relative to younger adults, and older adults also exhibited proportionally large beta desynchronization (ERD) responses during motor planning and execution compared to younger adults. Crucially, we found a significant relationship between spontaneous (resting) beta power and beta ERD magnitude in both primary motor cortices, above and beyond the effects of age. A similar link was found between beta ERD magnitude and movement duration. These findings suggest a direct linkage between beta reduction during movement and spontaneous activity in the motor cortex, such that as spontaneous beta power increases, a greater reduction in beta activity is required to execute movement. We propose that, on an individual level, the primary motor cortices have an

  6. Precessional parameters obtained from biased data of Hipparcos-FK5 proper motions

    NASA Astrophysics Data System (ADS)

    Martinez, M. J.; Marco, F. J.; Lopez, J. A.

    2008-04-01

    The Hipparcos catalogue provides a reference frame in optical wavelength for the new ICRS. The differences in the system of proper motions of Hipparcos and the previous materialization of the reference frame, the FK5, are expected to be caused only by the combined effects of the motion of the equinox of the FK5 as well as the Luni-solar and planetary precession, but several authors have signaled the existence of an inconsistency for the proper motion differences of the FK5-Hipparcos with the ∆p values corresponding to the Luni-solar precession as determined from VLBI and LLR It is a fact that the widely employed parametric models do not remove the bias in the random variables. The introduction of a non parametric method, combined with the inner product in L2 over S 2 shows the necessity of removing the bias. The precessional formulas should be rearranged to be used in this case. When applying this model, the obtained values for the precession corrections are very consistent with the ones currently adopted by the IAU.

  7. Differential Proper-Motion Measurements of The Cygnus Egg Nebula; The Presence of Fast Equatorial Outflows

    NASA Astrophysics Data System (ADS)

    Tomasino, Rachael; Ueta, T.; Ferguson, B. A.

    2013-01-01

    We present the results of differential proper-motion analyses of the dust shell structure in the Egg Nebula (RAFGL 2688, V1610 Cyg), based on the archived two-epoch imaging-polarimetric data in the optical taken with the Hubble Space Telescope. We measured the amount of motion of local structures and the signature concentric arcs in the nebula by determining their relative shifts over an interval of 7.25 yr. We discovered that the optical polarization characteristics of the Egg Nebula was influenced by the marginal optical thickness of the circumstellar shell and the illumination of the nebula was done in two-step mechanism - most of the nebula is illuminated by the secondary/dust-scattered starlight emanating from the bipolar lobes themselves due to the central concentration of dust grains of more than 10^3 AU diameter that regulates the seepage of the starlight from the central region. Nevertheless, based on two types of differential proper-motion analyses we revealed interesting dynamics of the lobes and concentric arcs, which should provide solid constraints on the subsequent theoretical/numerical investigations.

  8. Differential Proper-Motion Measurements of The Cygnus Egg Nebula; The Presence of Fast Equatorial Outflows

    NASA Astrophysics Data System (ADS)

    Tomasino, Rachael; Ueta, Toshiya; Ferguson, Brian

    2012-10-01

    We present the results of differential proper-motion analyses of the dust shell structure in the Egg Nebula (RAFGL 2688, V1610 Cyg), based on the archived two-epoch imaging-polarimetric data in the optical taken with the Hubble Space Telescope. We measured the amount of motion of local structures and the signature concentric arcs in the nebula by determining their relative shifts over an interval of 7.25 yr. We discovered that the optical polarization characteristics of the Egg Nebula was influenced by the marginal optical thickness of the circumstellar shell and the illumination of the nebula was done in two-step mechanism - most of the nebula is illuminated by the secondary/dust-scattered starlight emanating from the bipolar lobes themselves due to the central concentration of dust grains of more than 10^3 AU diameter that regulates the seepage of the starlight from the central region. Nevertheless, based on two types of differential proper-motion analyses we revealed interesting dynamics of the lobes and concentric arcs, which should provide solid constraints on the subsequent theoretical/numerical investigations.

  9. An HST Proper-motion Study of the Large-scale Jet of 3C273

    NASA Astrophysics Data System (ADS)

    Meyer, Eileen T.; Sparks, William B.; Georganopoulos, Markos; Anderson, Jay; van der Marel, Roeland; Biretta, John; Sohn, Sangmo Tony; Chiaberge, Marco; Perlman, Eric; Norman, Colin

    2016-02-01

    The radio galaxy 3C 273 hosts one of the nearest and best-studied powerful quasar jets. Having been imaged repeatedly by the Hubble Space Telescope (HST) over the past twenty years, it was chosen for an HST program to measure proper motions in the kiloparsec-scale resolved jets of nearby radio-loud active galaxies. The jet in 3C 273 is highly relativistic on sub-parsec scales, with apparent proper motions up to 15c observed by very long baseline interferometry. In contrast, we find that the kiloparsec-scale knots are compatible with being stationary, with a mean speed of -0.2 ± 0.5c over the whole jet. Assuming the knots are packets of moving plasma, an upper limit of 1c implies a bulk Lorentz factor Γ < 2.9. This suggests that the jet has either decelerated significantly by the time it reaches the kiloparsec scale, or that the knots in the jet are standing shock features. The second scenario is incompatible with the inverse Compton off the Cosmic Microwave Background (IC/CMB) model for the X-ray emission of these knots, which requires the knots to be in motion, but IC/CMB is also disfavored in the first scenario due to energetic considerations, in agreement with the recent finding of Meyer & Georganopoulos which ruled out the IC/CMB model for the X-ray emission of 3C 273 via gamma-ray upper limits.

  10. 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.

  11. A SEARCH FOR HIGH PROPER MOTION T DWARFS WITH Pan-STARRS1 + 2MASS + WISE

    SciTech Connect

    Liu, Michael C.; Deacon, Niall R.; Magnier, Eugene A.; Aller, Kimberly M.; Bowler, Brendan P.; Burgett, W. S.; Chambers, K. C.; Hodapp, K. W.; Kaiser, N.; Kudritzki, R.-P.; Morgan, J. S.; Tonry, J. L.; Wainscoat, R. J.; Dupuy, Trent J.; Redstone, Joshua; Goldman, Bertrand; Price, P. A.

    2011-10-20

    We have searched {approx}8200 deg{sup 2} for high proper motion ({approx}0.''5-2.''7 year{sup -1}) T dwarfs by combining first-epoch data from the Pan-STARRS1 (PS1) 3{pi} Survey, the Two Micron All Sky Survey (2MASS) All-Sky Point Source Catalog, and the WISE Preliminary Data Release. We identified two high proper motion objects with the very red (W1 - W2) colors characteristic of T dwarfs, one being the known T7.5 dwarf GJ 570D. Near-IR spectroscopy of the other object (PSO J043.5395+02.3995 {identical_to} WISEP J025409.45+022359.1) reveals a spectral type of T8, leading to a photometric distance of 7.2 {+-} 0.7 pc. The 2.''56 year{sup -1} proper motion of PSO J043.5+02 is the second highest among field T dwarfs, corresponding to a tangential velocity of 87 {+-} 8 km s{sup -1}. According to the Besancon galaxy model, this velocity indicates that its galactic membership is probably in the thin disk, with the thick disk an unlikely possibility. Such membership is in accord with the near-IR spectrum, which points to a surface gravity (age) and metallicity typical of the field population. We combine 2MASS, Sloan Digital Sky Survey, WISE, and PS1 astrometry to derive a preliminary parallax of 171 {+-} 45 mas (5.8{sup +2.0} {sub -1.2} pc), the first such measurement using PS1 data. The proximity and brightness of PSO J043.5+02 will facilitate future characterization of its atmosphere, variability, multiplicity, distance, and kinematics. The modest number of candidates from our search suggests that the immediate ({approx}10 pc) solar neighborhood does not contain a large reservoir of undiscovered T dwarfs earlier than about T8.

  12. Infrared spectrum and proper motion of the brown dwarf companion of HR 7329 in Tucanae

    NASA Astrophysics Data System (ADS)

    Guenther, E. W.; Neuhäuser, R.; Huélamo, N.; Brandner, W.; Alves, J.

    2001-01-01

    Up to now only four brown dwarf companions to normal stars have been found and confirmed by both spectroscopy and proper motion (namely Gl 229 B, G 196-3 B, Gl 570 D, and CoD-33 deg 7795 B). On the basis of an optical spectrum taken with HST/STIS Lowrance et al. (2000) recently pointed out another possible candidate companion. The companion candidate is located at a distance of 4{' '} from the A0-star HR 7329, which is considered as a member of a moving group of young stars in Tucanae located at a distance of only ~ 48 pc. In order to confirm or disregard the companion nature of the candidate, we have determined the proper motion of the brown dwarf candidate with an epoch difference of 1.8 years, and found that it is consistent with a co-moving companion of HR 7329. Additional to the proper motion measurement, we have also taken an H-band spectrum using ISAAC on the ESO-VLT. From this spectrum, we conclude that the companion candidate has spectral type M 7 to M 8, which is in agreement with the optical spectrum. We thus conclude that HR 7329 B is most likely a brown dwarf companion. The mass ratio of this pair (A0 to M 7-8, i.e. ~ 100:1) is the largest known among brown dwarf companions, which is relevant for studying the formation of brown dwarfs as companions. Based on observations obtained at the European Southern Observatory on Cerro Paranal and La Silla in program\\break 65.L-0144.

  13. Parallaxes of Southern Extremely Cool Objects. I. Targets, Proper Motions, and First Results

    NASA Astrophysics Data System (ADS)

    Andrei, A. H.; Smart, R. L.; Penna, J. L.; d'Avila, V. A.; Bucciarelli, B.; Camargo, J. I. B.; Crosta, M. T.; Daprà, M.; Goldman, B.; Jones, H. R. A.; Lattanzi, M. G.; Nicastro, L.; Pinfield, D. J.; da Silva Neto, D. N.; Teixeira, R.

    2011-02-01

    We present results from the PARallaxes of Southern Extremely Cool objects (PARSEC) program, an observational program begun in 2007 April to determine parallaxes for 122 L and 28 T southern hemisphere dwarfs using the Wide Field Imager on the ESO 2.2 m telescope. The results presented here include parallaxes of 10 targets from observations over 18 months and a first version proper motion catalog. The proper motions were obtained by combining PARSEC observations astrometrically reduced with respect to the Second US Naval Observatory CCD Astrograph Catalog, and the Two Micron All Sky Survey Point Source Catalog. The resulting median proper motion precision is 5 mas yr-1 for 195,700 sources. The 140 0.3 deg2 fields sample the southern hemisphere in an unbiased fashion with the exception of the galactic plane due to the small number of targets in that region. The proper motion distributions are shown to be statistically well behaved. External comparisons are also fully consistent. We will continue to update this catalog until the end of the program, and we plan to improve it including also observations from the GSC2.3 database. We present preliminary parallaxes with a 4.2 mas median precision for 10 brown dwarfs, two of which are within 10 pc. These increase the present number of L dwarfs by 20% with published parallaxes. Of the 10 targets, seven have been previously discussed in the literature: two were thought to be binary, but the PARSEC observations show them to be single; one has been confirmed as a binary companion and another has been found to be part of a binary system, both of which will make good benchmark systems. These results confirm that the foreseen precision of PARSEC can be achieved and that the large field of view will allow us to identify wide binary systems. Observations for the PARSEC program will end in early 2011 providing three to four years of coverage for all targets. The main expected outputs are: more than a 100% increase in the number of L

  14. VizieR Online Data Catalog: Proper motions and membership in NGC 6366 (Sariya+, 2015)

    NASA Astrophysics Data System (ADS)

    Sariya, D. P.; Yadav, R. K. S.

    2015-10-01

    Proper motions of the stars in the cluster region were determined using V filter images from the ESO archive (http://archive.eso.org/eso/esoarchivemain.html). The images used in this work were acquired using the 2.2m ESO/MPI telescope at La Silla, Chile. This telescope is equipped with a Wide Field Imager (WFI) camera. This camera contains a mosaic of 4x2, i.e., eight CCD chips, with 2048x4096-pixels each, making it possible to image an observational area of 34x33arcmin2. (1 data file).

  15. Identifying low-mass members of nearby star clusters using proper motion & color selection

    NASA Astrophysics Data System (ADS)

    Pitts, Mark A.

    I present a combined kinematic and photometric search for new, low-mass (m ≤ 0.2 M⊙ ) members of nearby (d < 300 pc) star clusters. Using both proper motion and color criteria, a total of 33 low-mass objects have been newly recognized as members of the Taurus, Praesepe, and Pleiades clusters. In addition, 18 potential cluster members are noted, and 4 members are recovered from previous member searches. Multi-epoch imaging was performed using i-band Megacam observations unique to this study, combined with archival CFH telescope data in the optical I and Z bands. Near-infrared detections were also acquired from the 2MASS survey. The imaging data were processed using the Pan-STARRS IPP data pipeline software in order to provide high-precision relative astrometry, from which proper motions were extracted. Low-resolution, near-infrared spectroscopy from the IRTF telescope gives confirmation on the membership status of the selected candidates. The addition of proper motion criteria to complement the often-used color selection allows for a more effective identification of low-mass cluster members whose broadband spectral features are similar to the bulk of galactic field objects lying along the line-of-sight. Culling the candidates using proper motion also significantly reduces the amount of candidates that require spectroscopic follow-up, even in the NIR color-space with the highest levels of field contamination. Comparison of the search results to a galactic field model by Robin et al. (2003) provides strong evidence that brighter member candidates in Taurus (i < 17) found to be of mid-M spectral types are highly likely to be clusters members rather than field dwarfs. While the addition of new members to the Praesepe and Pleiades clusters are minor compared to the current known population, there is suggestive evidence that the mass function of Taurus is significantly lacking in mid-M dwarfs, and in fact may actually resemble the mass functions of other similarly

  16. VLBI Water Maser Proper Motion Measurements in Star-Forming Regions

    NASA Astrophysics Data System (ADS)

    Torrelles, J. M.; Patel, N.; Gómez, J. F.; Anglada, G.; Uscanga, L.

    We review some of the recent water maser proper motion measurements in star-forming regions performed through VLBI multi-epoch observations. These observations are starting to reveal exciting perspectives, providing the full kinematics of the gas within the outflows/circumstellar disks around YSOs at scales of AUs, discovering new phenomena (e.g., isotropic mass ejections, watermaser "micro-structures" exhibiting remarkable coherent and well ordered spatio-kinematical behavior at AU scale), and opening new, puzzling questions related to the early stellar evolution.

  17. Vlbi Water Maser Proper Motion Measurements in Star-Forming Regions

    NASA Astrophysics Data System (ADS)

    Torrelles, J. M.; Patel, N.; Gómez, J. F.; Anglada, G.; Uscanga, L.

    2005-01-01

    We review some of the recent water maser proper motion measurements in star-forming regions performed through VLBI multi-epoch observations. These observations are starting to reveal exciting perspectives, providing the full kinematics of the gas within the outflows/circumstellar disks around YSOs at scales of AUs, discovering new phenomena (e.g., isotropic mass ejections, water maser "micro-structures" exhibiting remarkable coherent and well ordered spatio-kinematical behavior at AU scale), and opening new, puzzling questions related to the early stellar evolution.

  18. Messier 35 (NGC 2168) DANCe. I. Membership, proper motions, and multiwavelength photometry

    NASA Astrophysics Data System (ADS)

    Bouy, H.; Bertin, E.; Barrado, D.; Sarro, L. M.; Olivares, J.; Moraux, E.; Bouvier, J.; Cuillandre, J.-C.; Ribas, Á.; Beletsky, Y.

    2015-03-01

    Context. Messier 35 (NGC 2168) is an important young nearby cluster. Its age, richness and relative proximity make it an ideal target for stellar evolution studies. The Kepler K2 mission recently observed it and provided a high accuracy photometric time series of a large number of sources in this area of the sky. Identifying the cluster's members is therefore of high importance to optimize the interpretation and analysis of the Kepler K2 data. Aims: We aim to identify the cluster's members by deriving membership probabilities for the sources within 1° of the cluster's center, which is farther away than equivalent previous studies. Methods: We measure accurate proper motions and multiwavelength (optical and near-infrared) photometry using ground-based archival images of the cluster. We use these measurements to compute membership probabilities. The list of candidate members from the literature is used as a training set to identify the cluster's locus in a multidimensional space made of proper motions, luminosities, and colors. Results: The final catalog includes 338 892 sources with multiwavelength photometry. Approximately half (194 452) were detected at more than two epochs and we measured their proper motion and used it to derive membership probability. A total of 4349 candidate members with membership probabilities greater than 50% are found in this sample in the luminosity range between 10 mag and 22 mag. The slow proper motion of the cluster and the overlap of its sequence with the field and background sequences in almost all color-magnitude and color-color diagrams complicate the analysis and the contamination level is expected to be significant. Our study, nevertheless, provides a coherent and quantitative membership analysis of Messier 35 based on a large fraction of the best ground-based data sets obtained over the past 18 years. As such, it represents a valuable input for follow-up studies using, in particular, the Kepler K2 photometric time series

  19. USING RUNNING DIFFERENCE IMAGES TO TRACK PROPER MOTIONS OF XUV CORONAL INTENSITY ON THE SUN

    SciTech Connect

    Sheeley, N. R. Jr.; Warren, H. P.; Lee, J. E-mail: harry.warren@nrl.navy.mil; Chung, S.; Katz, J.; Namkung, M

    2014-12-20

    We have developed a procedure for observing and tracking proper motions of faint XUV coronal intensity on the Sun and have applied this procedure to study the collective motions of cellular plumes and the shorter-period waves in sunspots. Our space/time maps of cellular plumes show a series of tracks with the same 5-8 minute repetition times and ∼100 km s{sup –1} sky-plane speeds found previously in active-region fans and in coronal hole plumes. By synchronizing movies and space/time maps, we find that the tracks are produced by elongated ejections from the unipolar flux concentrations at the bases of the cellular plumes and that the phases of these ejections are uncorrelated from cell to cell. Thus, the large-scale motion is not a continuous flow, but is more like a system of independent conveyor belts all moving in the same direction along the magnetic field. In contrast, the proper motions in sunspots are clearly waves resulting from periodic disturbances in the sunspot umbras. The periods are ∼2.6 minutes, but the sky-plane speeds and wavelengths depend on the heights of the waves above the sunspot. In the chromosphere, the waves decelerate from 35-45 km s{sup –1} in the umbra to 7-8 km s{sup –1} toward the outer edge of the penumbra, but in the corona, the waves accelerate to ∼60-100 km s{sup –1}. Because chromospheric and coronal tracks originate from the same space/time locations, the coronal waves must emerge from the same umbral flashes that produce the chromospheric waves.

  20. Using Running Difference Images to Track Proper Motions of XUV Coronal Intensity on the Sun

    NASA Astrophysics Data System (ADS)

    Sheeley, N. R., Jr.; Warren, H. P.; Lee, J.; Chung, S.; Katz, J.; Namkung, M.

    2014-12-01

    We have developed a procedure for observing and tracking proper motions of faint XUV coronal intensity on the Sun and have applied this procedure to study the collective motions of cellular plumes and the shorter-period waves in sunspots. Our space/time maps of cellular plumes show a series of tracks with the same 5-8 minute repetition times and ~100 km s-1 sky-plane speeds found previously in active-region fans and in coronal hole plumes. By synchronizing movies and space/time maps, we find that the tracks are produced by elongated ejections from the unipolar flux concentrations at the bases of the cellular plumes and that the phases of these ejections are uncorrelated from cell to cell. Thus, the large-scale motion is not a continuous flow, but is more like a system of independent conveyor belts all moving in the same direction along the magnetic field. In contrast, the proper motions in sunspots are clearly waves resulting from periodic disturbances in the sunspot umbras. The periods are ~2.6 minutes, but the sky-plane speeds and wavelengths depend on the heights of the waves above the sunspot. In the chromosphere, the waves decelerate from 35-45 km s-1 in the umbra to 7-8 km s-1 toward the outer edge of the penumbra, but in the corona, the waves accelerate to ~60-100 km s-1. Because chromospheric and coronal tracks originate from the same space/time locations, the coronal waves must emerge from the same umbral flashes that produce the chromospheric waves.

  1. ON THE INTERPRETATION OF RECENT PROPER MOTION DATA FOR THE LARGE MAGELLANIC CLOUD

    SciTech Connect

    Bekki, Kenji

    2011-03-20

    Recent observational studies using the Hubble Space Telescope have derived the center-of-mass proper motion (CMPM) of the Large Magellanic Cloud (LMC). Although these studies carefully treated both rotation and perspective effects in deriving the proper motion (PM) for each of the sampled fields, they did not consider the effects of local random motion in the derivation. This means that the average PM of the fields (i.e., the observed CMPM) could significantly deviate from the true CMPM, because the effect of local random motion cannot be close to zero in making the average PM for the small number of fields ({approx}10). We discuss how significantly the observationally derived CMPM can deviate from the true CMPM by applying the same method as used in the observations for a dynamical model of the LMC with a known true CMPM. We find that the deviation can be as large as {approx}50 km s{sup -1} ({approx}0.21 mas yr{sup -1}), if the LMC has a thick disk and a maximum circular velocity of {approx}120 km s{sup -1}. We also find that the deviation depends both on the total number of sampled fields and on the structure and kinematics of the LMC. We therefore suggest that there is a possibility that the observed CMPM of the LMC deviates from the true one to some extent. We also show that a simple mean of PM for a large number of LMC fields ({approx}1000) can be much closer to the true CMPM.

  2. A deep proper motion catalog within the Sloan digital sky survey footprint

    SciTech Connect

    Munn, Jeffrey A.; Harris, Hugh C.; Tilleman, Trudy M.; Hippel, Ted von; Kilic, Mukremin; Liebert, James W.; Williams, Kurtis A.; DeGenarro, Steven; Jeffery, Elizabeth E-mail: hch@nofs.navy.mil E-mail: ted.vonhippel@erau.edu E-mail: jamesliebert@gmail.com E-mail: studiofortytwo@yahoo.com

    2014-12-01

    A new proper motion catalog is presented, combining the Sloan Digital Sky Survey (SDSS) with second epoch observations in the r band within a portion of the SDSS imaging footprint. The new observations were obtained with the 90prime camera on the Steward Observatory Bok 90 inch telescope, and the Array Camera on the U.S. Naval Observatory, Flagstaff Station, 1.3 m telescope. The catalog covers 1098 square degrees to r = 22.0, an additional 1521 square degrees to r = 20.9, plus a further 488 square degrees of lesser quality data. Statistical errors in the proper motions range from 5 mas year{sup −1} at the bright end to 15 mas year{sup −1} at the faint end, for a typical epoch difference of six years. Systematic errors are estimated to be roughly 1 mas year{sup −1} for the Array Camera data, and as much as 2–4 mas year{sup −1} for the 90prime data (though typically less). The catalog also includes a second epoch of r band photometry.

  3. Second Epoch Hubble Space Telescope Observations of Kepler's Supernova Remnant: The Proper Motions of Balmer Filaments

    NASA Astrophysics Data System (ADS)

    Sankrit, Ravi; Raymond, John C.; Blair, William P.; Long, Knox S.; Williams, Brian J.; Borkowski, Kazimierz J.; Patnaude, Daniel J.; Reynolds, Stephen P.

    2016-01-01

    We report on the proper motions of Balmer-dominated filaments in Kepler’s supernova remnant using high resolution images obtained with the Hubble Space Telescope at two epochs separated by about 10 years. We use the improved proper motion measurements and revised values of shock velocities to derive a distance to Kepler of {5.1}-0.7+0.8 kpc. The main shock around the northern rim of the remnant has a typical speed of 1690 km s-1 and is encountering material with densities of about 8 cm-3. We find evidence for the variation of shock properties over small spatial scales, including differences in the driving pressures as the shock wraps around a curved cloud surface. We find that the Balmer filaments ahead of the ejecta knot on the northwest boundary of the remnant are becoming fainter and more diffuse. We also find that the Balmer filaments associated with circumstellar material in the interior regions of the remnant are due to shocks with significantly lower velocities and that the brightness variations among these filaments trace the density distribution of the material, which may have a disk-like geometry. Based on observations made with the Hubble Space Telescope.

  4. On the systematics in apparent proper motions of radio sources observed by VLBI

    NASA Astrophysics Data System (ADS)

    Raposo-Pulido, V.; Lambert, S.; Capitaine, N.; Nilsson, T.; Heinkelmann, R.; Schuh, H.

    2015-08-01

    For about twenty years, several authors have been investigating the systematics in the apparent proper motions of radio source positions. In some cases, the theoretical work developed (Pyne et al., 1996) could not be assessed due to the few number of VLBI observations. In other cases, the effects attributed to apparent proper motion could not be related successfully because there were no significant evidences from a statistical point of view (MacMillan, 2005). In this work we provide considerations about the estimation of the coefficients of spherical harmonics, based on a three-step procedure used by Titov et al. (2011) and Titov and Lambert (2013). The early stage of this work has been to compare step by step the computations and estimation processes between the Calc/Solve (http://gemini.gsfc.nasa.gov/solve/) and VieVS software (Böhm et al., 2012). To achieve this, the results were analyzed and compared with the previous study done by Titov and Lambert (2013).

  5. A SUBSTELLAR COMMON PROPER-MOTION COMPANION TO THE PLEIAD H II 1348

    SciTech Connect

    Geissler, Kerstin; Metchev, Stanimir A.; Pham, Alfonse; Larkin, James E.; McElwain, Michael; Hillenbrand, Lynne A.

    2012-02-10

    We announce the identification of a proper-motion companion to the star H II 1348, a K5 V member of the Pleiades open cluster. The existence of a faint point source 1.''1 away from H II 1348 was previously known from adaptive optics imaging by Bouvier et al. However, because of a high likelihood of background star contamination and in the absence of follow-up astrometry, Bouvier et al. tentatively concluded that the candidate companion was not physically associated with H II 1348. We establish the proper-motion association of the pair from adaptive optics imaging with the Palomar 5 m telescope. Adaptive optics spectroscopy with the integral field spectrograph OSIRIS on the Keck 10 m telescope reveals that the companion has a spectral type of M8 {+-} 1. According to substellar evolution models, the M8 spectral type resides within the substellar mass regime at the age of the Pleiades. The primary itself is a known double-lined spectroscopic binary, which makes the resolved companion, H II 1348B, the least massive and widest component of this hierarchical triple system and the first substellar companion to a stellar primary in the Pleiades.

  6. A robust expansion proper motion distance to the extraordinary planetary nebula KjPn 8

    NASA Astrophysics Data System (ADS)

    Boumis, P.; Meaburn, J.

    2014-04-01

    Since the discovery by Lopez, Vasquez and Rodriguez of the giant lobes projecting from the otherwise innocuous planetary nebula, KjPn 8, it has been imperative to obtain a robust distance (D) determination. This has now been achieved by comparing an image of the lobes taken in 2011 with the Greek Aristarchos telescope with that (POSSI-R) obtained in 1954: the baseline for expansive proper motions has therefore being extended to 57 yr. These proper motions, combined with previous radial velocity measurements and tilt of the most energetic outflow with respect to the sight line, as determined from HST imagery of the nebular core, give D = 1.8 ± 0.3 kpc. This value then lets the kinetic energy (approx 1047 erg) of the most recent and energetic outflow to be determined. It could be significant that this energy is consistent with an Intermediate Luminosity Optical Transient (ILOT) origin of the latest ejection as proposed for other similar objects by Soker and Kashi.

  7. The first allwise proper motion discovery: Wisea J070720.50+170532.7

    SciTech Connect

    Wright, Edward L.; Mace, Gregory; McLean, Ian S.; Kirkpatrick, J. Davy; Gelino, Christopher R.; Fajardo-Acosta, Sergio; Eisenhardt, Peter R.; Stern, Daniel; Skrutskie, M. F.; Oza, Apurva; Nelson, M. J.; Cushing, Michael C.; Reid, I. Neill; Fumagalli, Michele; Burgasser, Adam J.

    2014-03-01

    While quality checking a new motion-aware co-addition of all 12.5 months of Wide-field Infrared Survey Explorer (WISE) data, we found that the source WISE J070720.48+170533.0 moved 0.''9 in six months. Backtracking this motion allowed us to identify this source as 2MASS J07071961+1705464, with several entries in the USNO B catalog. An astrometric fit to these archival data gives a proper motion of μ = 1793 ± 2 mas yr{sup –1} and a parallax of piv = 35 ± 42 mas. Photometry from WISE, 2MASS, and the POSS can be fit reasonably well by a blackbody with T = 3658 K and an angular radius of 4.36 × 10{sup –11} radians. No clear evidence of H{sub 2} collision-induced absorption is seen in the near-infrared. An optical spectrum shows broad deep CaH bands at 638 and 690 nm, broad deep Na D at 598.2 nm, and weak or absent TiO, indicating that this source is an ultra-subdwarf M star with a radial velocity v {sub rad} ≈ –21 ± 18 km s{sup –1} relative to the Sun. Given its apparent magnitude, the distance is about 39 ± 9 pc and the tangential velocity is probably ≈330 km s{sup –1}, but a more precise parallax is needed to be certain.

  8. VizieR Online Data Catalog: Proper Motions of 1160 Late-Type Stars (Fogh Olsen, 1970)

    NASA Astrophysics Data System (ADS)

    Olsen, F. H. J.

    1996-06-01

    Improved proper motions for the 1160 stars contained in the photometric catalog by Dickow et al. (1970A&AS....2....1D, II/38) are presented. Most of the proper motions are from the GC, transferred to the system of FK4. For stars not included in the GC, preliminary AGK or SAO proper motions are given. Olsen (1970A&AS....1..189O) describes the method of improvement. The mean errors of the centennial proper motions increase with increasing magnitude. In Right Ascension, these range from 0.0043/cos(dec) for very bright stars to 0.096/cos(dec) s for the faintest stars. In Declination, the range is from 0.065 to 1.14 arcsec. (1 data file).

  9. Absolute plate motions since 130 Ma constrained by subduction zone kinematics

    NASA Astrophysics Data System (ADS)

    Williams, Simon; Flament, Nicolas; Dietmar Müller, R.; Butterworth, Nathaniel

    2015-05-01

    The absolute motions of the lithospheric plates relative to the Earth's deep interior are commonly constrained using observations from paleomagnetism and age-progressive seamount trails. In contrast, an absolute plate motion (APM) model linking surface plate motions to subducted slab remnants mapped from seismic tomography has recently been proposed. Absolute plate motion models (or "reference frames") derived using different methodologies, different subsets of hotspots, or differing assumptions of hotspot motion, have contrasting implications for parameters that describe the long term state of the plate-mantle system, such as the balance between advance and retreat of subduction zones, plate velocities, and net lithospheric rotation. Previous studies of contemporary plate motions have used subduction zone kinematics as a constraint on the most likely APM model. Here we use a relative plate motion model to compute these values for the last 130 Myr for a range of alternative reference frames, and quantitatively compare the results. We find that hotspot and tomographic slab-remnant reference frames yield similar results for the last 70 Myr. For the 130-70 Ma period, where hotspot reference frames are less well constrained, these models yield a much more dispersed distribution of slab advance and retreat velocities. By contrast, plate motions calculated using the slab-remnant reference frame, or using a reference frame designed to minimise net rotation, yield more consistent subduction zone kinematics for times older than 70 Ma. Introducing the global optimisation of trench migration characteristics as a key criterion in the construction of APM models forms the foundation of a new method of constraining APMs (and in particular paleolongitude) in deep geological time.

  10. Lowell proper motion survey: Southern Hemisphere (Giclas, Burnham, and Thomas 1978). Documentation for the machine-readable version

    NASA Technical Reports Server (NTRS)

    Warren, Wayne H., Jr.

    1989-01-01

    The machine-readable version of the catalog, as it is currently being distributed from the Astronomical Data Center, is described. The catalog is a summary compilation of the Lowell Proper Motion Survey for the Southern Hemisphere, as completed to mid-1978 and published in the Lowell Observatory Bulletins. This summary catalog serves as a Southern Hemisphere companion to the Lowell Proper Motion Survey, Northern Hemisphere.

  11. Three very cool degenerate stars in Luyten common proper motion binaries - Implications for the age of the galactic disk

    NASA Technical Reports Server (NTRS)

    Hintzen, Paul; Oswalt, Terry D.; Liebert, James; Sion, Edward M.

    1989-01-01

    During the course of a spectroscopic study of Luyten common proper motion (CPM) stars, spectrophotometric observations have been obtained of three binaries containing degenerate stars with estimated absolute magnitudes M(V) of about 16. Each of the three pairs consists of a yellow degenerate star primary and a DC 13 + secondary 1.4-2.3 mag fainter. One of the primary stars is spectral class DC 7, another is a sharp-lined DA 8, and the third shows peculiar broad absorption features which we interpret as pressure-shifted C2 Swan bands. The LP 701 - 69/70 system has survived for over 8 billion years without disruption by passing stars, despite its 1500 a.u. orbital major axis. The three cool degenerate companions nearly double the available sample of stars at the low-luminosity terminus of the white dwarf cooling sequence. These findings appear consistent with the conclusion that degenerate stars in the old disk population have not had time to evolve to a luminosity fainter than M(V) about 16.2.

  12. Proper Motions in Terzan 5: Membership of the Multi-iron Subpopulations and First Constraint on the Orbit

    NASA Astrophysics Data System (ADS)

    Massari, D.; Dalessandro, E.; Ferraro, F. R.; Miocchi, P.; Bellini, A.; Origlia, L.; Lanzoni, B.; Rich, R. M.; Mucciarelli, A.

    2015-09-01

    By exploiting two sets of high-resolution images obtained with the Hubble Space Telescope Advanced Camera for Surveys/Wide Field Channel over a baseline of ∼10 years, we have measured relative proper motions (PMs) of ∼70,000 stars in the stellar system Terzan 5. The results confirm the membership of the three subpopulations with different iron abundances discovered in the system. The orbit of the system has been derived from a first estimate of its absolute PM, obtained by using bulge stars as a reference. The results of the integration of this orbit within an axisymmetric Galactic model exclude any external accretion origin for this cluster. Terzan 5 is known to have chemistry similar to the Galactic bulge; our findings support a kinematic link between the cluster and the bulge, further strengthening the possibility that Terzan 5 is the fossil remnant of one of the pristine clumps that originated the bulge. Based on observations (GO12933, GO9799) with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by AURA, Inc., under NASA contract NAS 5-26555.

  13. The new Milky Way satellites: alignment with the VPOS and predictions for proper motions and velocity dispersions

    NASA Astrophysics Data System (ADS)

    Pawlowski, Marcel S.; McGaugh, Stacy S.; Jerjen, Helmut

    2015-10-01

    The evidence that stellar systems surrounding the Milky Way (MW) are distributed in a Vast Polar Structure (VPOS) may be observationally biased by satellites detected in surveys of the northern sky. The recent discoveries of more than a dozen new systems in the Southern hemisphere thus constitute a critical test of the VPOS phenomenon. We report that the new objects are located close to the original VPOS, with half of the sample having offsets less than 20 kpc. The positions of the new satellite galaxy candidates are so well aligned that the orientation of the revised best-fitting VPOS structure is preserved to within 9°and the VPOS flattening is almost unchanged (31 kpc height). Interestingly, the shortest distance of the VPOS plane from the MW centre is now only 2.5 kpc, indicating that the new discoveries balance out the VPOS at the Galactic centre. The vast majority of the MW satellites are thus consistent with sharing a similar orbital plane as the Magellanic Clouds, confirming a hypothesis proposed by Kunkel & Demers and Lynden-Bell almost 40 yr ago. We predict the absolute proper motions of the new objects assuming they orbit within the VPOS. Independent of the VPOS results, we also predict the velocity dispersions of the new systems under three distinct assumptions: that they (i) are dark matter free star clusters obeying Newtonian dynamics, (ii) are dwarf satellites lying on empirical scaling relations of galaxies in dark matter haloes and (iii) obey modified Newtonian dynamics.

  14. Three very cool degenerate stars in Luyten common proper motion binaries - Implications for the age of the galactic disk

    NASA Astrophysics Data System (ADS)

    Hintzen, Paul; Oswalt, Terry D.; Liebert, James; Sion, Edward M.

    1989-11-01

    During the course of a spectroscopic study of Luyten common proper motion (CPM) stars, spectrophotometric observations have been obtained of three binaries containing degenerate stars with estimated absolute magnitudes M(V) of about 16. Each of the three pairs consists of a yellow degenerate star primary and a DC 13 + secondary 1.4-2.3 mag fainter. One of the primary stars is spectral class DC 7, another is a sharp-lined DA 8, and the third shows peculiar broad absorption features which we interpret as pressure-shifted C2 Swan bands. The LP 701 - 69/70 system has survived for over 8 billion years without disruption by passing stars, despite its 1500 a.u. orbital major axis. The three cool degenerate companions nearly double the available sample of stars at the low-luminosity terminus of the white dwarf cooling sequence. These findings appear consistent with the conclusion that degenerate stars in the old disk population have not had time to evolve to a luminosity fainter than M(V) about 16.2.

  15. VizieR Online Data Catalog: Proper motions and BV photometry in NGC 1513 (Frolov+, 2002)

    NASA Astrophysics Data System (ADS)

    Frolov, V. N.; Jilinski, E. G.; Ananjevskaja, J. K.; Poljakov, E. V.; Bronnikova, N. M.; Gorshanov, D. L.

    2002-10-01

    The results of astrometric and photometric investigations of the poorly studied open cluster NGC 1513 are presented. The proper motions of 333 stars with a root-mean-square error of 1.9mas/yr were obtained by means of the automated measuring complex "Fantasy". Eight astrometric plates covering the time interval of 101 years were measured and a total of 141 astrometric cluster members identified. BV CCD-photometry was obtained for stars in an area 17'x17' centered on the cluster. Altogether 33 stars with high reliability were considered to be cluster members by two criteria. The estimated age of NGC 1513 is 2.54E+08 years. (2 data files).

  16. A proper motion survey in the area of the galactic cluster in Coma Berenices

    NASA Astrophysics Data System (ADS)

    Cova S., J.

    1981-12-01

    An attempt is made to test the accuracy of the block measurement method for the determination of positions from the Oxford Zone I of the Carte du Ciel catalog, and to determine the precise proper motions for all stars, down to the catalog's photographic limiting magnitude, in a 4.7 arcmin-diameter area which covers a large part of the cluster in Coma Berenices. The earliest epoch employed consists of nine fields of the Oxford Zone which were simultaneously reduced by means of block adjustment methods, while the latest epoch is based on plates taken with a Schmidt telescope. Intermediate epochs were taken from Heckmann (1929) and the AGK catalogs, with the latter serving as a reference system throughout.

  17. A Common Proper Motion Stellar Companion to HAT-P-7

    NASA Astrophysics Data System (ADS)

    Narita, Norio; Takahashi, Yasuhiro H.; Kuzuhara, Masayuki; Hirano, Teruyuki; Suenaga, Takuya; Kandori, Ryo; Kudo, Tomoyuki; Sato, Bun'ei; Suzuki, Ryuji; Ida, Shigeru; Nagasawa, Makiko; Abe, Lyu; Brandner, Wolfgang; Brandt, Timothy D.; Carson, Joseph; Egner, Sebastian E.; Feldt, Markus; Goto, Miwa; Grady, Carol A.; Guyon, Olivier; Hashimoto, Jun; Hayano, Yutaka; Hayashi, Masahiko; Hayashi, Saeko S.; Henning, Thomas; Hodapp, Klaus W.; Ishii, Miki; Iye, Masanori; Janson, Markus; Knapp, Gillian R.; Kusakabe, Nobuhiko; Kwon, Jungmi; Matsuo, Taro; Mayama, Satoshi; McElwain, Michael W.; Miyama, Shoken M.; Morino, Jun-Ichi; Moro-Martin, Amaya; Nishimura, Tetsuo; Pyo, Tae-Soo; Serabyn, Eugene; Suto, Hiroshi; Takami, Michihiro; Takato, Naruhisa; Terada, Hiroshi; Thalmann, Christian; Tomono, Daigo; Turner, Edwin L.; Watanabe, Makoto; Wisniewski, John P.; Yamada, Toru; Takami, Hideki; Usuda, Tomonori; Tamura, Motohide

    2012-12-01

    We report that HAT-P-7 has a common proper motion stellar companion. The companion is located at ˜3."9 to the east and estimated to be an M5.5V dwarf based on its colors. We also confirm the presence of a third companion, which was first reported by Winn et al. (2009, ApJ, 703, L99), based on long-term radial velocity measurements. We revisit the migration mechanism of HAT-P-7b given to the presence of those companions, and propose the sequential Kozai migration as a likely scenario in this system. This scenario may explain the reason for an outlier in the discussion of the spin-orbit alignment timescale for HAT-P-7b by Albrecht et al. (2012, ApJ, 757, 18).

  18. VizieR Online Data Catalog: NEOWISE/AllWISE high proper motion objects (Schneider+, 2016)

    NASA Astrophysics Data System (ADS)

    Schneider, A. C.; Greco, J.; Cushing, M. C.; Kirkpatrick, J. D.; Mainzer, A.; Gelino, C. R.; Fajardo-Acosta, S. B.; Bauer, J.

    2016-04-01

    The NEOWISE reactivation mission was carried out using the W1 (3.4um) and W2 (4.6um) passbands of the WISE telescope. Considering the ~4 year time baseline between the first sky pass of NEOWISE and the first WISE epochs, our 1" search radius gives us a nominal minimum proper motion limit of ~250mas/yr (see section 2). Low-resolution (R=75-120) spectra were acquired for several sources with the upgraded SpeX spectrograph at the 3m NASA Infrared Telescope Facility (IRTF) on Mauna Kea. A summary of all IRTF/SpeX observations is given in Table 11. Three targets were observed with the Double Spectrograph on the Hale 5m telescope on the night of UT 2015 September 07. (3 data files).

  19. A Common Proper Motion Stellar Companion to HAT-P-7

    NASA Technical Reports Server (NTRS)

    Grady, Carol A.; McElwain, Michael W.; Narita, Norio; Takahashi, Yasuhiro H.; Kuzuhara, Masayuki; Hirano, Teruyuki; Suenaga, Takuya

    2012-01-01

    We report that HAT-P-7 has a common proper motion stellar companion. The companion is located at approx. 3.9 arcsec to the east and estimated as an M5.5V dwarf based on its colors. We also confirm the presence of the third companion, which was first reported by Winn et al. (2009), based on long-term radial velocity measurements. We revisit the migration mechanism of HAT-P-7b given the presence of those companions, and propose sequential Kozai migration as a likely scenario in this system. This scenario may explain the reason for an outlier in the discussion of the spin-orbit alignment timescale for HAT-P-7b by Albrecht et al. (2012).

  20. Modelling the 3D morphology and proper motions of the planetary nebula NGC 6302

    NASA Astrophysics Data System (ADS)

    Uscanga, L.; Velázquez, P. F.; Esquivel, A.; Raga, A. C.; Boumis, P.; Cantó, J.

    2014-08-01

    We present 3D hydrodynamical simulations of an isotropic fast wind interacting with a previously ejected toroidally shaped slow wind in order to model both the observed morphology and the kinematics of the planetary nebula (PN) NGC 6302. This source, also known as the Butterfly nebula, presents one of the most complex morphologies ever observed in PNe. From our numerical simulations, we have obtained an intensity map for the Hα emission to make a comparison with the Hubble Space Telescope (HST) observations of this object. We have also carried out a proper motion (PM) study from our numerical results, in order to compare with previous observational studies. We have found that the two interacting stellar wind model reproduce well the morphology of NGC 6302, and while the PMs in the models are similar to the observations, our results suggest that an acceleration mechanism is needed to explain the Hubble-type expansion found in HST observations.

  1. VizieR Online Data Catalog: 1103 parallaxes and proper motions from URAT (Finch+, 2016)

    NASA Astrophysics Data System (ADS)

    Finch, C. T.; Zacharias, N.

    2016-07-01

    We present 1103 trigonometric parallaxes and proper motions from the United States Naval Observatory (USNO) Robotic Astrometric Telescope (URAT) observations taken at the Naval Observatory Flagstaff Station (NOFS). URAT observes through a single filter (part of the dewar window) to provide a fixed bandpass of about 680 to 760nm. The clear aperture of the USNO astrograph is 206mm with a focal length of only 2m. A single exposure covers 28 square degrees with a resolution of 0.9arcsec/pixel. Each of the four large CCDs in the focal plane covers a 2.65 by 2.65 deg area on the sky. Data of all three years of operations (2012 April to 2015 June) at the NOFS are used here for this parallax investigation. For more details about the project, instrument, and observing the reader is referred to the URAT1 paper (Zacharias et al. 2015, cat. I/329). (3 data files).

  2. Gaia reference frame amid quasar variability and proper motion patterns in the data

    NASA Astrophysics Data System (ADS)

    Bachchan, R. K.; Hobbs, D.; Lindegren, L.

    2016-05-01

    Context. Gaia's very accurate astrometric measurements will allow the optical realisation of the International Celestial Reference System to be improved by a few orders of magnitude. Several sets of quasars are used to define a kinematically stable non-rotating reference frame with the barycentre of the solar system as its origin. Gaia will also observe a large number of galaxies. Although they are not point-like, it may be possible to determine accurate positions and proper motions for some of their compact bright features. Aims: The optical stability of the quasars is critical, and we investigate how accurately the reference frame can be recovered. Various proper motion patterns are also present in the data, the best known is caused by the acceleration of the solar system barycentre, presumably, towards the Galactic centre. We review some other less well-known effects that are not part of standard astrometric models. Methods: We modelled quasars and galaxies using realistic sky distributions, magnitudes, and redshifts. Position variability was introduced using a Markov chain model. The reference frame was determined using the algorithm developed for the Gaia mission, which also determines the acceleration of the solar system. We also tested a method for measuring the velocity of the solar system barycentre in a cosmological frame. Results: We simulated the recovery of the reference frame and the acceleration of the solar system and conclude that they are not significantly disturbed by quasar variability, which is statistically averaged. However, the effect of a non-uniform sky distribution of the quasars can result in a correlation between the parameters describing the spin components of the reference frame and the acceleration components, which degrades the solution. Our results suggest that an attempt should be made to astrometrically determine the redshift-dependent apparent drift of galaxies that is due to our velocity relative to the cosmic microwave

  3. Gaia reference frame amid quasar variability and proper motion patterns in the data

    NASA Astrophysics Data System (ADS)

    Bachchan, R. K.; Hobbs, D.; Lindegren, L.

    2016-04-01

    Context. Gaia's very accurate astrometric measurements will allow the optical realisation of the International Celestial Reference System to be improved by a few orders of magnitude. Several sets of quasars are used to define a kinematically stable non-rotating reference frame with the barycentre of the solar system as its origin. Gaia will also observe a large number of galaxies. Although they are not point-like, it may be possible to determine accurate positions and proper motions for some of their compact bright features. Aims: The optical stability of the quasars is critical, and we investigate how accurately the reference frame can be recovered. Various proper motion patterns are also present in the data, the best known is caused by the acceleration of the solar system barycentre, presumably, towards the Galactic centre. We review some other less well-known effects that are not part of standard astrometric models. Methods: We modelled quasars and galaxies using realistic sky distributions, magnitudes, and redshifts. Position variability was introduced using a Markov chain model. The reference frame was determined using the algorithm developed for the Gaia mission, which also determines the acceleration of the solar system. We also tested a method for measuring the velocity of the solar system barycentre in a cosmological frame. Results: We simulated the recovery of the reference frame and the acceleration of the solar system and conclude that they are not significantly disturbed by quasar variability, which is statistically averaged. However, the effect of a non-uniform sky distribution of the quasars can result in a correlation between the parameters describing the spin components of the reference frame and the acceleration components, which degrades the solution. Our results suggest that an attempt should be made to astrometrically determine the redshift-dependent apparent drift of galaxies that is due to our velocity relative to the cosmic microwave

  4. PG1258+593 and its common proper motion magnetic white dwarf counterpart

    NASA Astrophysics Data System (ADS)

    Girven, J.; Gänsicke, B. T.; Külebi, B.; Steeghs, D.; Jordan, S.; Marsh, T. R.; Koester, D.

    2010-05-01

    We confirm SDSSJ130033.48+590407.0 as a common proper motion companion to the well-studied hydrogen-atmosphere (DA) white dwarf PG1258+593 (GD322). The system lies at a distance of 68 +/- 3pc, where the angular separation of 16.1 +/- 0.1arcsec corresponds to a minimum binary separation of 1091 +/- 7au. SDSSJ1300+5904 is a cool (Teff = 6300 +/- 300K) magnetic white dwarf (B ~= 6mG). PG1258+593 is a DA white dwarf with Teff = 14790 +/- 77K and logg = 7.87 +/- 0.02. Using the white dwarf mass-radius relation implies the masses of SDSSJ1300+5904 and PG1258+593 are 0.54 +/- 0.06 and 0.54 +/- 0.01Msolar, respectively, and therefore a cooling age difference of 1.67 +/- 0.05Gyr. Adopting main-sequence lifetimes from stellar models, we derive an upper limit of 2.2Msolar for the mass of the progenitor of PG1258+593. A plausible range of initial masses is 1.4-1.8 Msolar for PG1258+593 and 2-3 Msolar for SDSSJ1300+5904. Our analysis shows that white dwarf common proper motion binaries can potentially constrain the white dwarf initial mass-final mass relation and the formation mechanism for magnetic white dwarfs. The magnetic field of SDSSJ1300+5904 is consistent with an Ap progenitor star. A common envelope origin of the system cannot be excluded, but requires a triple system as progenitor.

  5. Globular Cluster Orbits from HST Proper Motions: Constraining the Formation and Mass of the Milky Way Halo

    NASA Astrophysics Data System (ADS)

    Sohn, S. Tony; Van Der Marel, Roeland P.; Deason, Alis J.; Bellini, Andrea; Besla, Gurtina; Watkins, Laura

    2016-06-01

    The globular cluster (GC) system of the Milky Way (MW) provides important information on the MW's present structure and past evolution. GCs in the halo are particularly useful tracers; because of their long dynamical timescales, their orbits retain imprints of their origin or accretion history. Full 3D motions are required to calculate past orbits. While most GCs have known line of sight velocities, accurate proper motion (PM) measurements are currently available for only a few halo GCs. Our goal is to create the first high-quality PM database for halo GCs. We have identified suitable 1st-epoch data in the HST Archive for 20 halo GCs at 10-100 kpc from the Galactic Center. We are in the process of obtaining the necessary 2nd-epoch data to determine absolute PMs of the target GCs through our HST program GO-14235. We will use the same advanced astrometric techniques that allowed us to measure the PMs of M31 and Leo I. Previous studies of the halo GC system based on e.g., stellar populations, metallicities, RR Lyrae properties, and structural properties have revealed a dichotomy between old and young halo GCs. This may reflect distinct formation scenarios (in situ vs. accreted). Orbit calculations based on our PMs will directly test this. The PMs will also yield the best handle yet on the velocity anisotropy profile of any tracer population in the halo. This will resolve the mass-anisotropy degeneracy to provide an improved estimate of the MW mass, which is at present poorly known. In summary, our project will deliver the first accurate PMs for halo GCs, and will significantly increase our understanding of the formation, evolution, and mass of the MW.

  6. CHARACTERIZING THE COOL KOIs. III. KOI 961: A SMALL STAR WITH LARGE PROPER MOTION AND THREE SMALL PLANETS

    SciTech Connect

    Muirhead, Philip S.; Johnson, John Asher; Morton, Timothy D.; Pineda, John Sebastian; Bottom, Michael; Crepp, Justin R.; Kirby, Evan N.; Apps, Kevin; Carter, Joshua A.; Fabrycky, Daniel C.; Hamren, Katherine; Schlawin, Everett; Covey, Kevin R.; Stassun, Keivan G.; Pepper, Joshua; Hebb, Leslie; Howard, Andrew W.; Isaacson, Howard T.; Marcy, Geoffrey W.; and others

    2012-03-10

    We characterize the star KOI 961, an M dwarf with transit signals indicative of three short-period exoplanets discovered by the Kepler mission. We proceed by comparing KOI 961 to Barnard's Star, a nearby, well-characterized mid-M dwarf. We compare colors, optical and near-infrared spectra, and find remarkable agreement between the two, implying similar effective temperatures and metallicities. Both are metal-poor compared to the Solar neighborhood, have low projected rotational velocity, high absolute radial velocity, large proper motion, and no quiescent H{alpha} emission-all of which are consistent with being old M dwarfs. We combine empirical measurements of Barnard's Star and expectations from evolutionary isochrones to estimate KOI 961's mass (0.13 {+-} 0.05 M{sub Sun }), radius (0.17 {+-} 0.04 R{sub Sun }), and luminosity (2.40 Multiplication-Sign 10{sup -3.0{+-}0.3} L{sub Sun }). We calculate KOI 961's distance (38.7 {+-} 6.3 pc) and space motions, which, like Barnard's Star, are consistent with a high scale-height population in the Milky Way. We perform an independent multi-transit fit to the public Kepler light curve and significantly revise the transit parameters for the three planets. We calculate the false-positive probability for each planet candidate, and find a less than 1% chance that any one of the transiting signals is due to a background or hierarchical eclipsing binary, validating the planetary nature of the transits. The best-fitting radii for all three planets are less than 1 R{sub Circled-Plus }, with KOI 961.03 being Mars-sized (R{sub P} = 0.57 {+-} 0.18 R{sub Circled-Plus }), and they represent some of the smallest exoplanets detected to date.

  7. St. Helena, Edmond Halley, the discovery of stellar proper motion, and the mystery of Aldebaran

    NASA Astrophysics Data System (ADS)

    Brandt, John C.

    2010-07-01

    St. Helena was the location of Halley's observatory in 1677-1678. The site has been identified and I report on a visit in November 2006. The principal use of the observatory was to accurately map the stars of the southern sky. In the summary of his work, the Catalogus Stellarum Australium, Halley noted evidence for the "... mutability of the fixed Stars." He would not return to this subject until much later in his career. Halley later compared contemporary positions of Arcturus, Sirius, and Aldebaran with the ancient positions recorded in the Almagest. He found that these stars had apparently moved southward by >30' and concluded that they had their own particular motions. Modern proper motion measurements are consistent with this conclusion for Arcturus and Sirius, but are not even close for Aldebaran. While some authors are aware of the problem, it generally is not mentioned in books on the history of astronomy or in biographical works on Halley. Errors in the Almagest positions can be ruled out; an error of 30' in the early eighteenth century position is highly unlikely; a misidentification of the star is implausible; and, we are left with the conclusion that there is most likely an error in Halley's calculations.

  8. OPTICAL PROPER MOTION MEASUREMENTS OF THE M87 JET: NEW RESULTS FROM THE HUBBLE SPACE TELESCOPE

    SciTech Connect

    Meyer, Eileen T.; Sparks, W. B.; Biretta, J. A.; Anderson, Jay; Sohn, Sangmo Tony; Van der Marel, Roeland P.; Norman, Colin; Nakamura, Masanori

    2013-09-10

    We report new results from a Hubble Space Telescope archival program to study proper motions in the optical jet of the nearby radio galaxy M87. Using over 13 yr of archival imaging, we reach accuracies below 0.1c in measuring the apparent velocities of individual knots in the jet. We confirm previous findings of speeds up to 4.5c in the inner 6'' of the jet, and report new speeds for optical components in the outer part of the jet. We find evidence of significant motion transverse to the jet axis on the order of 0.6c in the inner jet features, and superluminal velocities parallel and transverse to the jet in the outer knot components, with an apparent ordering of velocity vectors possibly consistent with a helical jet pattern. Previous results suggested a global deceleration over the length of the jet in the form of decreasing maximum speeds of knot components from HST-1 outward, but our results suggest that superluminal speeds persist out to knot C, with large differentials in very nearby features all along the jet. We find significant apparent accelerations in directions parallel and transverse to the jet axis, along with evidence for stationary features in knots D, E, and I. These results are expected to place important constraints on detailed models of kiloparsec-scale relativistic jets.

  9. DIFFERENTIAL PROPER-MOTION STUDY OF THE CIRCUMSTELLAR DUST SHELL OF THE ENIGMATIC OBJECT, HD 179821

    SciTech Connect

    Ferguson, Brian A.; Ueta, Toshiya

    2010-03-10

    HD 179821 is an enigmatic evolved star that possesses characteristics of both a post-asymptotic giant branch (post-AGB) star and a yellow hypergiant, and there has been no evidence that unambiguously defines its nature. These two hypotheses are products of an indeterminate distance, presumed to be 1 kpc or 6 kpc. We have obtained the two-epoch Hubble Space Telescope Wild Field Planetary Camera 2 data of its circumstellar shell, which shows multiple concentric arcs extending out to about 8''. We have performed differential proper-motion measurements on distinct structures within the circumstellar shell of this mysterious star in hopes of determining the distance to the object, and thereby distinguishing the nature of this enigmatic stellar source. Upon investigation, rather than azimuthal radially symmetric expansion, we discovered a bulk motion of the circumstellar shell of (2.41 +- 0.43, 2.97 +- 0.32) mas yr{sup -1}. This corresponded to a translational interstellar medium (ISM) flow of (1.28 +- 0.95, 7.27 +- 0.75) mas yr{sup -1} local to the star. This finding implies that the distance to HD 179821 should be rather small in order for its circumstellar shell to preserve its highly intact spherical structure in the presence of the distorting ISM flow, therefore favoring the proposition that HD 179821 is a post-AGB object.

  10. Proper Motions of Dwarf Spheroidal Galaxies from Hubble Space Telescope Imaging. 3; Measurement for URSA Minor

    NASA Technical Reports Server (NTRS)

    Piatek, Slawomir; Pryor, Carlton; Bristow, Paul; Olszewski, Edward W.; Harris, Hugh C.; Mateo, Mario; Minniti, Dante; Tinney, Christopher G.

    2005-01-01

    This article presents a measurement of the proper motion of the Ursa Minor dwarf spheroidal galaxy determined from images taken with the Hubble Space Telescope in two distinct fields. Each field contains a quasi-stellar object that serves as the "reference point". Integrating the motion of Ursa Minor in a realistic potential for the Milky Way produces orbital elements. The perigalacticon and apogalacticon are 40 (10, 76) and 89 (78, 160) kpc, respectively, where the values in the parentheses represent the 95% confidence intervals derived from Monte Carlo experiments. The eccentricity of the orbit is 0.39 (0.09, 0.79), and the orbital period is 1.5 (1.1, 2.7) Gyr. The orbit is retrograde and inclined by 124 degrees (94 deg, 36 deg ) to the Galactic plane. Ursa Minor is not a likely member of a proposed stream of galaxies on similar orbits around the Milky Way, nor is the plane of its orbit coincident with a recently proposed planar alignment of galaxies around the Milky Way. Comparing the orbits of Ursa Minor and Carina shows no reason for the different star formation histories of these two galaxies. Ursa Minor must contain dark matter to have a high probability of having survived disruption by the Galactic tidal force until the present.

  11. The imprint of proper motion of nonlinear structures on the cosmic microwave background

    NASA Technical Reports Server (NTRS)

    Tuluie, Robin; Laguna, Pablo

    1995-01-01

    We investigate the imprint of nonlinear matter condensations on the cosmic microwave background (CMB) in an Omega = 1, cold dark matter (CDM) model universe. Temperature anisotropies are obtained by numerically evolving matter inhomogeneities and CMB photons from the beginning of decoupling until the present epoch. The underlying density field produced by the inhomogeneities is followed from the linear, through the weakly clustered, into the fully nonlinear regime. We concentrate on CMB temperature distortions arising from variations in the gravitational potentials of nonlinear structures. We find two sources of temperature fluctuations produced by time-varying potentials: (1) anisotropies due to intrinsic changes in the gravitational potentials of the inhomogeneities and (2) anisotropies generated by the peculiar, bulk motion of the structures across the microwave sky. Both effects generate CMB anisotropies in the range of 10(exp -7) approximately less than or equal to (Delta T/T) approximately less than or equal to 10(exp -6) on scales of approximately 1 deg. For isolated structures, anisotropies due to proper motion exhibit a dipole-like signature in the CMB sky that in principle could yield information on the transverse velocity of the structures.

  12. Alignment between seafloor spreading directions and absolute plate motions through time

    NASA Astrophysics Data System (ADS)

    Williams, Simon E.; Flament, Nicolas; Müller, R. Dietmar

    2016-02-01

    The history of seafloor spreading in the ocean basins provides a detailed record of relative motions between Earth's tectonic plates since Pangea breakup. Determining how tectonic plates have moved relative to the Earth's deep interior is more challenging. Recent studies of contemporary plate motions have demonstrated links between relative plate motion and absolute plate motion (APM), and with seismic anisotropy in the upper mantle. Here we explore the link between spreading directions and APM since the Early Cretaceous. We find a significant alignment between APM and spreading directions at mid-ocean ridges; however, the degree of alignment is influenced by geodynamic setting, and is strongest for mid-Atlantic spreading ridges between plates that are not directly influenced by time-varying slab pull. In the Pacific, significant mismatches between spreading and APM direction may relate to a major plate-mantle reorganization. We conclude that spreading fabric can be used to improve models of APM.

  13. HST Astrometry in the 30 Doradus Region: Measuring Proper Motions of Individual Stars in the Large Magellanic Cloud

    NASA Astrophysics Data System (ADS)

    Platais, Imants; van der Marel, Roeland P.; Lennon, Daniel J.; Anderson, Jay; Bellini, Andrea; Sabbi, Elena; Sana, Hugues; Bedin, Luigi R.

    2015-09-01

    We present measurements of positions and relative proper motions in the 30 Doradus region of the LMC. We detail the construction of a single-epoch astrometric reference frame, based on specially designed observations obtained with the two main imaging instruments Advanced Camera for Surveys/Wide Field Channel and Wide Field Camera 3/UVIS on board the Hubble Space Telescope (HST). Internal comparisons indicate a sub milliarcsecond (mas) precision in the positions and the presence of semi-periodic systematics with a mean amplitude of ˜0.8 mas. We combined these observations with numerous archival images taken with Wide Field Planetary Camera 2 and spanning 17 years. The precision of the resulting proper motions for well-measured stars around the massive cluster Radcliffe 136 (R136) can be as good as ˜20 μas yr-1, although the true accuracy of proper motions is generally lower due to the residual systematic errors. The observed proper-motion dispersion for our highest-quality measurements is ˜0.1 mas yr-1. Our catalog of positions and proper motions contains 86,590 stars down to V ˜ 25 and over a total area of ˜70 square arcmin. We examined the proper motions of 105 relatively bright stars and identified a total of six candidate runaway stars. We are able to tentatively confirm the runaway status of star VFTS 285, consistent with the findings from line of sight velocities, and to show that this star has likely been ejected from R136. This study demonstrates that with HST it is now possible to reliably measure proper motions of individual stars in the nearest dwarf galaxies such as the LMC.

  14. Dimer motion on a periodic substrate: Spontaneous symmetry breaking and absolute negative mobility

    NASA Astrophysics Data System (ADS)

    Speer, David; Eichhorn, Ralf; Evstigneev, Mykhaylo; Reimann, Peter

    2012-06-01

    We consider two coupled particles moving along a periodic substrate potential with negligible inertia effects (overdamped limit). Even when the particles are identical and the substrate spatially symmetric, a sinusoidal external driving of appropriate amplitude and frequency may lead to spontaneous symmetry breaking in the form of a permanent directed motion of the dimer. Thermal noise restores ergodicity and thus zero net velocity, but entails arbitrarily fast diffusion of the dimer for sufficiently weak noise. Moreover, upon application of a static bias force, the dimer exhibits a motion opposite to that force (absolute negative mobility). The key requirement for all these effects is a nonconvex interaction potential of the two particles.

  15. Spectroscopic follow-up of L- and T-type proper-motion member candidates in the Pleiades

    NASA Astrophysics Data System (ADS)

    Zapatero Osorio, M. R.; Béjar, V. J. S.; Martín, E. L.; Gálvez Ortiz, M. C.; Rebolo, R.; Bihain, G.; Henning, Th.; Boudreault, S.; Goldman, B.; Mundt, R.; Caballero, J. A.; Miles-Páez, P. A.

    2014-12-01

    We report on the near-infrared (JHK-bands) low-resolution spectroscopy and red optical (Z-band) photometry of seven proper-motion, very low-mass substellar member candidates of the Pleiades cluster with magnitudes in the interval J = 17.5-20.8 and K = 16.1-18.5 mag. Spectra were acquired for six objects with the LIRIS and NIRSPEC instruments mounted on the 4.2-m William Herschel and the 10-m Keck II telescopes, respectively. Z-band images of two of the faintest candidates were collected with the ACAM instrument on the WHT. The new data confirm the low temperatures of all seven Pleiades proper motion candidates. From the imaging observations, we find extremely red Z - J and Z - K colors that suggest that the faintest target, Calar Pleiades 25, has a Galactic rather than extragalactic nature. We tentatively classify the spectroscopic targets from early-L to ~T0 and suggest that the L/T transition, which accounts for the onset of methane absorption at 2.1 μm, may take place at J ≈ 20.3 and K ≈ 17.8 mag in the Pleiades (absolute values of MJ ≈ 14.7 and MK ≈ 12.2 mag). We find evidence of likely low-gravity atmospheres based on the presence of triangular-shape H-band fluxes and the high flux ratio K/H (compatible with red H - K colors) of Calar Pleiades 20, 21, and 22, which is a feature also seen in field low-gravity dwarfs. Weak K i absorption lines at around 1.25 μm are probably seen in two targets. These observations add support to the cluster membership of all seven objects in the Pleiades. The trend delineated by the spectroscopic sequence of Pleiades late-M and L dwarfs resembles that of the field. With masses estimated at 0.012-0.015 M⊙ (solar metallicity and 120 Myr), Calar Pleiades 20 (L6±1), 21 (L7±1), and 22 (L/T) may become the coolest and least massive Pleiades members that are corroborated with photometry, astrometry, and spectroscopy. Calar Pleiades 25 (<0.012 M⊙) is a firm free-floating planetary-mass candidate in the Pleiades. Appendix

  16. Discovery of new companions to high proper motion stars from the VVV Survey

    NASA Astrophysics Data System (ADS)

    Ivanov, Valentin D.; Minniti, Dante; Hempel, Maren; Kurtev, Radostin; Toledo, Ignacio; Saito, Roberto K.; Alonso-García, Javier; Beamín, Juan Carlos; Borissova, Jura; Catelan, Márcio; Chené, André-Nicolas; Emerson, Jim; González, Óscar A.; Lucas, Phillip W.; Martín, Eduardo L.; Rejkuba, Marina; Gromadzki, Mariusz

    2013-12-01

    Context. The severe crowding in the direction of the inner Milky Way suggests that the census of stars within a few tens of parsecs in that direction may not be complete. Aims: We searched for new nearby object companions of known high proper motion (HPM) stars located towards the densest regions of the southern Milky Way where the background contamination presented a major problem to previous observations. Methods: The common proper motion (PM) method was used. We inspected the area around 167 known HPM (≥200 mas yr-1) stars: 67 in the disk and 100 in the bulge. Multi-epoch images were provided by the Two Micron All Sky Survey (2MASS) and the VISTA Variables in Via Lactea (VVV). The VVV is a new on-going ZYJHKS plus multi-epoch KS survey of ~562 deg2 of the Milky Way bulge and inner southern disk. Results: Seven new co-moving companions were discovered around known HPM stars (L 149-77, LHS 2881, L 200-41, LHS 3188, LP 487-4, LHS 5333, and LP 922-16); six known co-moving pairs were recovered (LTT 5140 A + LTT 5140 B, L 412-3 + L 412-4, LP 920-25 + LP 920-26, LTT 6990 A + LTT 6990 B, M 124.22158.2900 + M 124.22158.2910, and GJ 2136 A + GJ 2136 B); a pair of stars that was thought to be co-moving was found to have different proper motions (LTT 7318, LTT 7319); published HPMs of eight stars were not confirmed (C* 1925, C* 1930, C* 1936, CD-60 4613, LP 866-17, OGLE BUL-SC20 625107, OGLE BUL-SC21 298351, and OGLE BUL-SC32 388121); last but not least, spectral types ranging from G8V to M5V were derived from new infrared spectroscopy for seventeen stars, members of the co-moving pairs. Conclusions: The seven newly discovered stars constitute ~4% of the nearby HPM star list, but this is not a firm limit on the HPM star incompleteness because our starting point - the HPM list assembled from the literature - is incomplete itself, missing many nearby HPM M- and L-type objects, and it is contaminated with non-HPM stars. We have demonstrated that the superior sub

  17. Mass of the Local Group from Proper Motions of Distant Dwarf Galaxies

    NASA Astrophysics Data System (ADS)

    van der Marel, Roeland

    2010-09-01

    The Local Group and its two dominant spirals, the Milky Way and M31, have become the benchmark for testing many aspects of cosmological and galaxy formation theories, due to many exciting new discoveries in the past decade. However, it is difficult to put results in a proper cosmological context, because our knowledge of the mass M of the Local Group remains uncertain by a factor 4. In units of 10^{12} solar masses, a spherical infall model for the zero-velocity surface gives M 1.3; the sum of estimates for the Milky Way and M31 masses gives M 2.6; and the Local Group Timing argument for the M31 orbit gives M 5.6. It is possible to discriminate between the proposed masses by calculating the orbits of galaxies at the edge of the Local Group, which requires knowledge of transverse velocity components. We therefore propose to use ACS/WFC to determine the proper motions of the 4 dwarf galaxies near the edge of the Local Group {Cetus, Leo A, Tucana, Sag DIG} for which deep first epoch data {with 5-7 year time baselines} already exist in the HST Archive. Our team has extensive expertise with HST astrometric science, and our past/ongoing work for, e.g., Omega Cen, LMC/SMC and M31 show that the necessary astrometric accuracy is within the reach of HST's demonstrated capabilities. We have developed, tested, and published a new technique that uses compact background galaxies as astrometric reference sources, and we have already reduced the first epoch data. The final predicted transverse velocity accuracy, 36 km/s when averaged over the sample, will be sufficient to discriminate between each of the proposed Local Group masses at 2-sigma significance {4-sigma between the most extreme values}. Our project will yield the most accurate Local Group mass determination to date, and only HST can achieve the required accuracy.

  18. Subduction trench migration as a constraint on absolute plate motions since 130 Ma

    NASA Astrophysics Data System (ADS)

    Williams, Simon; Flament, Nicolas; Müller, Dietmar; Butterworth, Nathan

    2015-04-01

    The absolute motions of the lithospheric plates relative to the Earth's deep interior are commonly constrained using observations from paleomagnetism and age-progressive seamount trails. In contrast, a reference frame linking surface plate motions to subducted slab remnants mapped from seismic tomography has recently been proposed. Absolute plate motion (APM) models (or "reference frames") derived using different methodologies, different subsets of hotspots, or differing assumptions of hotspot motion, have contrasting implications for parameters that describe the long term state of the plate-mantle system, such as the balance between advance and retreat of subduction zones, plate velocities, and net lithospheric rotation. Previous studies of contemporary plate motions have used subduction zone kinematics as a constraint on the most likely APM model. Here we use a relative plate motion model to compute these values for the last 130 Myr for a range of alternative reference frames, and quantitatively compare the results. We find that hotspot and tomographic slab-remnant reference frames yield similar results for the last 70 Myr. For the 130-70 Ma period, where hotspot reference frames are less well constrained, these models yield a much more dispersed distribution of slab advance and retreat velocities. By contrast, plate motions calculated using the slab-remnant reference frame, or using a reference frame designed to minimise net rotation, yield more consistent subduction zone kinematics for times older than 70 Ma. Introducing the global minimisation of trench migration rates as a key criterion in the construction of APM models forms the foundation of a new method of constraining APMs (and in particular paleolongitude) in deep geological time.

  19. UCAC3 PROPER MOTION SURVEY. I. DISCOVERY OF NEW PROPER MOTION STARS IN UCAC3 WITH 0.''40 yr{sup -1} > {mu} {>=} 0.''18 yr{sup -1} BETWEEN DECLINATIONS -90{sup 0} AND -47{sup 0}

    SciTech Connect

    Finch, Charlie T.; Zacharias, Norbert; Henry, Todd J.

    2010-09-15

    This paper presents 442 new proper motion stellar systems in the southern sky between declinations -90{sup 0} and -47{sup 0} with 0.''40 yr{sup -1} > {mu} {>=} 0.''18 yr{sup -1}. These systems constitute a 25.3% increase in new systems for the same region of the sky covered by previous SuperCOSMOS RECONS (SCR) searches that used Schmidt plates as the primary source of discovery. Among the new systems are 25 multiples, plus an additional 7 new common proper motion (CPM) companions to previously known primaries. All stars have been discovered using the third U.S. Naval Observatory (USNO) CCD Astrograph Catalog (UCAC3). A comparison of the UCAC3 proper motions to those from the Hipparcos, Tycho-2, Southern Proper Motion (SPM4), and SuperCOSMOS efforts is presented and shows that UCAC3 provides similar values and precision to the first three surveys. The comparison between UCAC3 and SuperCOSMOS indicates that proper motions in R.A. are systematically shifted in the SuperCOSMOS data but are consistent in decl. data, while overall showing a significantly higher scatter. Distance estimates are derived for stars having SuperCOSMOS Sky Survey B{sub J} , R{sub 59F}, and I{sub IVN} plate magnitudes and Two-Micron All Sky Survey infrared photometry. We find 15 systems estimated to be within 25 pc, including UPM 1710-5300 our closest new discovery estimated at 13.5 pc. Such new discoveries suggest that more nearby stars are yet to be found in these slower proper motion regimes, indicating that more work is needed to develop a complete map of the solar neighborhood.

  20. DIFFERENTIAL PROPER-MOTION MEASUREMENTS OF THE CYGNUS EGG NEBULA: THE PRESENCE OF EQUATORIAL OUTFLOWS

    SciTech Connect

    Ueta, Toshiya; Tomasino, Rachael L.; Ferguson, Brian A.

    2013-08-01

    We present the results of differential proper-motion analyses of the Egg Nebula (RAFGL 2688, V1610 Cyg) based on the archived two-epoch optical data taken with the Hubble Space Telescope. First, we determined that the polarization characteristics of the Egg Nebula are influenced by the higher optical depth of the central regions of the nebula (i.e., the 'dustsphere' of {approx}10{sup 3} AU radius), causing the nebula to illuminate in two steps-the direct starlight is first channeled into bipolar cavities and then scattered off to the rest of the nebula. We then measured the amount of motion of local structures and the signature concentric arcs by determining their relative shifts over the 7.25 yr interval. Based on our analysis, which does not rely on the single-scattering assumption, we concluded that the lobes have been excavated by a linear expansion along the bipolar axis for the past {approx}400 yr, while the concentric arcs have been generated continuously and moving out radially at about 10 km s{sup -1} for the past {approx}5500 yr, and there appears to be a colatitudinally increasing trend in the radial expansion velocity field of the concentric arcs. Numerical investigations into the mass-loss modulation by the central binary system exist, which predict such a colatitudinally increasing expansion velocity field in the spiral-shock trails of the mass-loss ejecta. Therefore, the Egg Nebula may represent a rare edge-on case of the binary-modulated circumstellar environs, corroborating the previous theoretical predictions.

  1. Motion Verified Red Stars (MoVeRS): A Catalog of Proper Motion Selected Low-mass Stars from WISE, SDSS, and 2MASS

    NASA Astrophysics Data System (ADS)

    Theissen, Christopher A.; West, Andrew A.; Dhital, Saurav

    2016-02-01

    We present a photometric catalog of 8,735,004 proper motion selected low-mass stars (KML-spectral types) within the Sloan Digital Sky Survey (SDSS) footprint, from the combined SDSS Data Release 10 (DR10), Two Micron All-Sky Survey (2MASS) point-source catalog (PSC), and Wide-field Infrared Survey Explorer (WISE) AllWISE catalog. Stars were selected using r - i, i - z, r - z, z - J, and z - W1 colors, and SDSS, WISE, and 2MASS astrometry was combined to compute proper motions. The resulting 3,518,150 stars were augmented with proper motions for 5,216,854 earlier type stars from the combined SDSS and United States Naval Observatory B1.0 catalog (USNO-B). We used SDSS+USNO-B proper motions to determine the best criteria for selecting a clean sample of stars. Only stars whose proper motions were greater than their 2σ uncertainty were included. Our Motion Verified Red Stars catalog is available through SDSS CasJobs and VizieR.

  2. U Orionis - The evolution and proper motion of the OH maser envelope

    NASA Astrophysics Data System (ADS)

    Chapman, Jessica M.; Cohen, R. J.; Saikia, D. J.

    1991-03-01

    The Jodrell Bank MERLIN array was used to map the OH 1665- and 1667-MHz masers in the circumstellar envelope of U Orionis in 1984, 1986 and 1987. The OH masers lie within a region of extent 130 x 180 sq AU, and have complex distributions which are different for each line and polarization. The masers show clumpy structures with a typical clump size of about 25 AU. The strongest emission is from a ring of radius 60 AU which is interpreted as part of an expanding, tilted torus. The ring has a proper motion of 5.4 + or - 1.4 mas/yr corresponding to a transverse expansion velocity of 7 km/s for the period-luminosity distance to U Orionis of 260 pc. This expansion velocity is also indicated by a compact blueshifted maser spot which lies near the projected stellar position. OH maser emission is also detected from a redshifted filament which appears to project over a considerable radial depth in the envelope and varies in intensity in an erratic fashion.

  3. Photometric and Proper Motion Study of the Neglected Open Cluster NGC 2215

    NASA Astrophysics Data System (ADS)

    Fitzgerald, M. T.; Inwood, L.; McKinnon, D. H.; Dias, W. S.; Sacchi, M.; Scott, B.; Zolinski, M.; Danaia, L.; Edwards, R.

    2015-06-01

    Optical UBVRI photometric measurements using the Faulkes Telescope North were taken in early 2011 and combined with 2MASS JHKs and WISE infrared photometry as well as UCAC4 proper motion data in order to estimate the main parameters of the galactic open cluster NGC 2215 of which large uncertainty exists in the current literature. Fitting a King model we estimate a core radius of 1.‧12 ± 0.‧04 (0.24 ± 0.01 pc) and a limiting radius of 4.‧3 ± 0.‧5 (0.94 ± 0.11 pc) for the cluster. The results of isochrone fits indicates an age of log (t)=8.85+/- 0.10 with a distance of d=790+/- 90 pc, a metallicity of [Fe/H]=-0.40+/- 0.10 dex, and a reddening of E(B-V)=0.26+/- 0.04. A proportion of the work in this study was undertaken by Australian and Canadian upper secondary school students involved in the Space to Grow astronomy education project, and is the first scientific publication to have utilized our star cluster photometry curriculum materials.

  4. VizieR Online Data Catalog: Photometry and proper motions in Praesepe (Wang+, 2014)

    NASA Astrophysics Data System (ADS)

    Wang, P. F.; Chen, W. P.; Lin, C. C.; Pandey, A. K.; Huang, C. K.; Panwar, N.; Lee, C. H.; Tsai, M. F.; Tang, C.-H.; Goldman, B.; Burgett, W. S.; Chambers, K. C.; Draper, P. W.; Flewelling, H.; Grav, T.; Heasley, J. N.; Hodapp, K. W.; Huber, M. E.; Jedicke, R.; Kaiser, N.; Kudritzki, R.-P.; Luppino, G. A.; Lupton, R. H.; Magnier, E. A.; Metcalfe, N.; Monet, D. G.; Morgan, J. S.; Onaka, P. M.; Price, P. A.; Stubbs, C. W.; Sweeney, W.; Tonry, J. L.; Wainscoat, R. J.; Waters, C.

    2016-08-01

    Data used in this study include photometry and proper motion measurements within a 5° radius around the Praesepe center (R.A.=08h40m, decl.=+19°42', J2000). Archival data were taken from the 2MASS Point Sources Catalog (2MASS; cat. II/246), PPMXL (Roeser et al. 2010, cat. I/317), and Panoramic Survey Telescope And Rapid Response (Pan-STARRS). Pan-STARRS is a wide-field (7deg2) imaging system, with a 1.8m, f/4.4 telescope, equipped with a 1.4 giga-pixel camera. The prototype (PS1), located atop Haleakala, Maui, USA, has been patrolling the entire sky north of -30° declination since mid-2010 with a combination of gP1, rP1, iP1, zP1, and yP1 bands. The PS1 filters differ slightly from those of the SDSS. The gP1 filter extends 20nm redward of gSDSS for greater sensitivity and lower systematics for photometric redshift estimates. SDSS has no corresponding y filter (Tonry et al. 2012, cat. J/ApJ/750/99). Upon the completion of its 3.5yr mission by early 2014, PS1 will provide reliable photometry and astrometry. Table1 lists the properties of the 1040 candidates. (1 data file).

  5. The Quintuplet cluster - A young massive cluster study based on proper motion membership

    NASA Astrophysics Data System (ADS)

    Hußmann, Benjamin

    2014-01-01

    Young massive clusters define the high mass range of current clustered star formation and are frequently found in starburst and interacting galaxies. As - with the exception of the nearest galaxies within the local group - extragalactic clusters can not be resolved into individual stars, the few young massive clusters in the Milky Way and the Magellanic Clouds might serve as templates for unresolved young massive clusters in more distant galaxies. Due to their high masses, these clusters sample the full range of stellar masses. In combination with the small or negligible spreads in age or metallicity of their stellar populations, this makes these object unique laboratories to study stellar evolution, especially in the high mass range.Furthermore, they allow to probe the initial mass function, which describes the distribution of masses of a stellar population at its birth, in its entirety. The Quintuplet cluster is one of three known young massive clusters residing in the central molecular zone and is located at a projected distance of 30 pc from the Galactic centre. Because of the rather extreme conditions in this region, a potential dependence of the outcome of the star formation process on the environmental conditions under which the star formation event takes place might leave its imprint in the stellar mass function. As the Quintuplet cluster is lacking a dense core and shows a somewhat dispersed appearance, it is crucial to effectively distinguish between cluster stars and the rich population of stars from the Galactic field along the line of sight to the Galactic centre in order to measure its present-day mass function. In this thesis, a clean sample of cluster stars is derived based on the common bulk proper motion of the cluster with respect to the Galactic field and a subsequent colour selection. The diffraction limited resolution of multi-epoch near-infrared imaging observations obtained at the ESO Very Large Telescope with adaptive optics correction

  6. PROPER MOTIONS AND ORIGINS OF SGR 1806-20 AND SGR 1900+14

    SciTech Connect

    Tendulkar, Shriharsh P.; Kulkarni, Shrinivas R.; Cameron, P. Brian

    2012-12-10

    We present results from high-resolution infrared observations of magnetars SGR 1806-20 and SGR 1900+14 over 5 years using laser-supported adaptive optics at the 10 m Keck Observatory. Our measurements of the proper motions of these magnetars provide robust links between magnetars and their progenitors and provide age estimates for magnetars. At the measured distances of their putative associations, we measure the linear transverse velocity of SGR 1806-20 to be 350 {+-} 100 km s{sup -1} and of SGR 1900+14 to be 130 {+-} 30 km s{sup -1}. The transverse velocity vectors for both magnetars point away from the clusters of massive stars, solidifying their proposed associations. Assuming that the magnetars were born in the clusters, we can estimate the braking index to be {approx}1.8 for SGR 1806-20 and {approx}1.2 for SGR 1900+14. This is significantly lower than the canonical value of n = 3 predicted by the magnetic dipole spin-down suggesting an alternative source of dissipation such as twisted magnetospheres or particle winds.

  7. The systems of the positions and proper motions in the star catalogues AGK 3, AGK 3 RN, and N 30

    NASA Astrophysics Data System (ADS)

    Schwan, H.

    1985-08-01

    Comparisons between the catalogue N 30, the AGK 3 RN by Corbin, and modern catalogues of observation have shown that there are significant systematic differences between the systems of the bright and faint stars in N 30, mainly in the proper motions in right ascension. No significant deviations between the FK 4 system and Corbin's catalogue AGK 3 RN have been found. The systematic errors in the AGK 3 proper motions have been estimated from the catalogue comparison AGK 3 RN-AGK 3, adopting the AGK 3 RN catalogue as a representative of the FK 4 system. Maximum deviations up to -0s.060 cy-1 and -0arcsec.80 cy-1 occur in a few regions on the sky, but in general the deviations AGK 3 RN-AGK 3 do not exceed ±0s.020 cy-1 and ±0arcsec.30 cy-1 for the proper motion systems in right ascension and declination.

  8. The First X-Ray Proper-Motion Measurements of the Forward Shock in the Northeastern Limb of Sn 1006

    NASA Technical Reports Server (NTRS)

    Katsuda, Satoru; Petre, Robert; Long, Knox S.; Reynolds, Stephen P.; Winkler, P. Frank; Mori, Koji; Tsunemi, Hiroshi

    2009-01-01

    We report on the first X-ray proper-motion measurements of the nonthermally-dominated forward shock in the northeastern limb of SN 1006, based on two Chandra observations taken in 2000 and 2008. We find that the proper motion of the forward shock is about 0.48"/yr and does not vary around the rim within the approx.10% measurement uncertainties. The proper motion measured is consistent with that determined by the previous radio observations. The mean expansion index of the forward shock is calculated to be approx..0.54 which matches the value expected based on an evolutionary model of a Type Ia supernova with either a power-law or an exponential ejecta density profile. Assuming pressure equilibrium around the periphery from the thermally-dominated northwestern rim to the nonthermally-dominated northeastern rim, we estimate the ambient density to the northeast of SN 1006 to be approx..0.085/cu cm.

  9. FIRST RESULTS FROM Pan-STARRS1: FAINT, HIGH PROPER MOTION WHITE DWARFS IN THE MEDIUM-DEEP FIELDS

    SciTech Connect

    Tonry, J. L.; Flewelling, H. A.; Deacon, N. R.; Burgett, W. S.; Chambers, K. C.; Kaiser, N.; Kudritzki, R.-P.; Hodapp, K. W.; Magnier, E. A.; Morgan, J. S.; Wainscoat, R. J.; Stubbs, C. W.; Kilic, M.; Chornock, R.; Berger, E.; Price, P. A.

    2012-01-20

    The Pan-STARRS1 survey has obtained multi-epoch imaging in five bands (Pan-STARRS1 g{sub P1}, r{sub P1}, i{sub P1}, z{sub P1}, and y{sub P1}) on 12 'Medium-Deep fields', each of which spans a 3.{sup 0}3 circle. For the period between 2009 April and 2011 April these fields were observed 50-200 times. Using a reduced proper motion diagram, we have extracted a list of 47 white dwarf (WD) candidates whose Pan-STARRS1 astrometry indicates a non-zero proper motion at the 6{sigma} level, with a typical 1{sigma} proper motion uncertainty of 10 mas yr{sup -1}. We also used astrometry from the Sloan Digital Sky Survey (when available) and USNO-B to assess our proper motion fits. None of the WD candidates exhibits evidence of statistically significant parallaxes, with a typical 1{sigma} uncertainty of 8 mas. Twelve of these candidates are known WDs, including the high proper motion (1.''7 yr{sup -1}) WD LHS 291. We confirm seven more objects as WDs through optical spectroscopy. Based on the Pan-STARRS1 colors, ten of the stars are likely to be cool WDs with 4170 K proper motion WDs that are part of the old thick disk and halo.

  10. THE M31 VELOCITY VECTOR. I. HUBBLE SPACE TELESCOPE PROPER-MOTION MEASUREMENTS

    SciTech Connect

    Sohn, Sangmo Tony; Anderson, Jay; Van der Marel, Roeland P.

    2012-07-01

    We present the first proper-motion (PM) measurements for the galaxy M31. We obtained new V-band imaging data with the Hubble Space Telescope ACS/WFC and the WFC3/UVIS instruments of three fields: a spheroid field near the minor axis, an outer disk field along the major axis, and a field on the Giant Southern Stream. The data provide five to seven year time baselines with respect to pre-existing deep first-epoch observations of the same fields. We measure the positions of thousands of M31 stars and hundreds of compact background galaxies in each field. High accuracy and robustness is achieved by building and fitting a unique template for each individual object. The average PM for each field is obtained from the average motion of the M31 stars between the epochs with respect to the background galaxies. For the three fields, the observed PMs ({mu}{sub W}, {mu}{sub N}) are, in units of mas yr{sup -1}, (- 0.0458, -0.0376) {+-} (0.0165, 0.0154), (- 0.0533, -0.0104) {+-} (0.0246, 0.0244), and (- 0.0179, -0.0357) {+-} (0.0278, 0.0272), respectively. The ability to average over large numbers of objects and over the three fields yields a final displacement accuracy of a few thousandths of a pixel, corresponding to only 12 {mu}as yr{sup -1}. This is comparable to what has been achieved for other Local Group galaxies using Very Long Baseline Array observations of water masers. Potential systematic errors are controlled by an analysis strategy that corrects for detector charge transfer inefficiency, spatially and time-dependent geometric distortion, and point-spread function variations. The robustness of the PM measurements and uncertainties are supported by the fact that data from different instruments, taken at different times and with different telescope orientations, as well as measurements of different fields, all yield statistically consistent results. Papers II and III of this series explore the implications of the new measurements for our understanding of the history

  11. Proper motions and CCD photometry of stars in the region of the open cluster NGC 6866

    NASA Astrophysics Data System (ADS)

    Frolov, V. N.; Ananjevskaja, Yu. K.; Gorshanov, D. L.; Polyakov, E. V.

    2010-05-01

    We present the results of our comprehensive study of the Galactic open star cluster NGC 6866. The positions of stars in the investigated region have been obtained with the “Fantasy” automatic measuring machine from 10 plates of the normal astrograph at the Pulkovo Astronomical Observatory. The size of the investigated field is 40' × 40', the limiting magnitude is B ˜ 16{·/ m }6, and the maximum epoch difference is 79 yr. For 1202 field stars, we have determined the relative proper motions with an rms error of 2.5 mas yr-1. Out of them, 423 stars may be considered cluster members with a probability P > 70% according to the astrometric criterion. Photometric diagrams have been used as an additional criterion. We have performed two-color BV CCD photometry of stars with the Pulkovo ZA-320M mirror astrograph. The U magnitudes from the literature have also been used to construct the two-color diagrams. A total of 267 stars have turned out to be members of NGC 6866 according to the two criteria. We present refined physical parameters of the cluster and its age estimate (5.6 × 108 yr). The cluster membership of red and blue giants, variable, double, and multiple stars is considered. We have found an almost complete coincidence of the positions of one of the stars in the region (a cluster nonmember) and a soft X-ray source in the ROSAT catalog. The “Fantasy” automatic measuring machine is described in the Appendix.

  12. The Proper Motion of the Galactic Center Pulsar Relative to Sagittarius A*

    NASA Astrophysics Data System (ADS)

    Bower, Geoffrey C.; Deller, Adam; Demorest, Paul; Brunthaler, Andreas; Falcke, Heino; Moscibrodzka, Monika; O'Leary, Ryan M.; Eatough, Ralph P.; Kramer, Michael; Lee, K. J.; Spitler, Laura; Desvignes, Gregory; Rushton, Anthony P.; Doeleman, Sheperd; Reid, Mark J.

    2015-01-01

    We measure the proper motion of the pulsar PSR J1745-2900 relative to the Galactic center massive black hole, Sgr A*, using the Very Long Baseline Array (VLBA). The pulsar has a transverse velocity of 236 ± 11 km s–1 at position angle 22 ± 2 deg east of north at a projected separation of 0.097 pc from Sgr A*. Given the unknown radial velocity, this transverse velocity measurement does not conclusively prove that the pulsar is bound to Sgr A* however, the probability of chance alignment is very small. We do show that the velocity and position are consistent with a bound orbit originating in the clockwise disk of massive stars orbiting Sgr A* and a natal velocity kick of <~ 500 km s–1. An origin among the isotropic stellar cluster is possible but less probable. If the pulsar remains radio-bright, multiyear astrometry of PSR J1745-2900 can detect its acceleration and determine the full three-dimensional orbit. We also demonstrate that PSR J1745-2900 exhibits the same angular broadening as Sgr A* over a wavelength range of 3.6 cm to 0.7 cm, further confirming that the two sources share the same interstellar scattering properties. Finally, we place the first limits on the presence of a wavelength-dependent shift in the position of Sgr A*, i.e., the core shift, one of the expected properties of optically thick jet emission. Our results for PSR J1745-2900 support the hypothesis that Galactic center pulsars will originate from the stellar disk and deepen the mystery regarding the small number of detected Galactic center pulsars.

  13. Ancient eruptions of η Carinae: A tale written in proper motions

    NASA Astrophysics Data System (ADS)

    Kiminki, Megan M.; Reiter, Megan; Smith, Nathan

    2016-09-01

    We analyze eight epochs of Hubble Space Telescope Hα+[N II] imaging of η Carinae's outer ejecta. Proper motions of nearly 800 knots reveal that the detected ejecta are divided into three apparent age groups, dating to around 1250 A.D., to around 1550 A.D., and to during or shortly before the Great Eruption of the 1840s. Ejecta from these groups reside in different locations and provide a firm constraint that η Car experienced multiple major eruptions prior to the 19th century. The 1250 and 1550 events did not share the same axisymmetry as the Homunculus; the 1250 event was particularly asymmetric, even one-sided. In addition, the ejecta in the S ridge, which have been associated with the Great Eruption, appear to predate the ejection of the Homunculus by several decades. We detect essentially ballistic expansion across multiple epochs. We find no evidence for large-scale deceleration of the observed knots that could power the soft X-ray shell by plowing into surrounding material, suggesting that the observed X-rays arise instead from fast, rarefied ejecta from the 1840s overtaking the older dense knots. Early deceleration and subsequent coasting cannot explain the origin of the older outer ejecta-significant episodic mass loss prior to the 19th century is required. The timescale and geometry of the past eruptions provide important constraints for any theoretical physical mechanisms driving η Car's behavior. Non-repeating mechanisms such as the merger of a close binary in a triple system would require additional complexities to explain the observations.

  14. THE PROPER MOTION OF THE GALACTIC CENTER PULSAR RELATIVE TO SAGITTARIUS A*

    SciTech Connect

    Bower, Geoffrey C.; Deller, Adam; Falcke, Heino; Demorest, Paul; Brunthaler, Andreas; Eatough, Ralph P.; Kramer, Michael; Lee, K. J.; Spitler, Laura; Desvignes, Gregory; Moscibrodzka, Monika; O'Leary, Ryan M.; Rushton, Anthony P.; Doeleman, Sheperd; Reid, Mark J.

    2015-01-10

    We measure the proper motion of the pulsar PSR J1745-2900 relative to the Galactic center massive black hole, Sgr A*, using the Very Long Baseline Array (VLBA). The pulsar has a transverse velocity of 236 ± 11 km s{sup –1} at position angle 22 ± 2 deg east of north at a projected separation of 0.097 pc from Sgr A*. Given the unknown radial velocity, this transverse velocity measurement does not conclusively prove that the pulsar is bound to Sgr A*; however, the probability of chance alignment is very small. We do show that the velocity and position are consistent with a bound orbit originating in the clockwise disk of massive stars orbiting Sgr A* and a natal velocity kick of ≲ 500 km s{sup –1}. An origin among the isotropic stellar cluster is possible but less probable. If the pulsar remains radio-bright, multiyear astrometry of PSR J1745-2900 can detect its acceleration and determine the full three-dimensional orbit. We also demonstrate that PSR J1745-2900 exhibits the same angular broadening as Sgr A* over a wavelength range of 3.6 cm to 0.7 cm, further confirming that the two sources share the same interstellar scattering properties. Finally, we place the first limits on the presence of a wavelength-dependent shift in the position of Sgr A*, i.e., the core shift, one of the expected properties of optically thick jet emission. Our results for PSR J1745-2900 support the hypothesis that Galactic center pulsars will originate from the stellar disk and deepen the mystery regarding the small number of detected Galactic center pulsars.

  15. SLoWPoKES-II: 100,000 Wide Binaries Identified in SDSS without Proper Motions

    NASA Astrophysics Data System (ADS)

    Dhital, Saurav; West, Andrew A.; Stassun, Keivan G.; Schluns, Kyle J.; Massey, Angela P.

    2015-08-01

    We present the Sloan Low-mass Wide Pairs of Kinematically Equivalent Stars (SLoWPoKES)-II catalog of low-mass visual binaries identified from the Sloan Digital Sky Survey (SDSS) by matching photometric distances. The candidate pairs are vetted by comparing the stellar information. The candidate pairs are vetted by comparing the stellar density at their respective Galactic positions to Monte Carlo realizations of a simulated Milky Way. In this way, we are able to identify large numbers of bona fide wide binaries without the need for proper motions. Here, 105,537 visual binaries with angular separations of ˜1-20″ were identified, each with a probability of chance alignment of ≤5%. This is the largest catalog of bona fide wide binaries to date, and it contains a diversity of systems—in mass, mass ratios, binary separations, metallicity, and evolutionary states—that should facilitate follow-up studies to characterize the properties of M dwarfs and white dwarfs. There is a subtle but definitive suggestion of multiple populations in the physical separation distribution, supporting earlier findings. We suggest that wide binaries are composed of multiple populations, most likely representing different formation modes. There are 141 M7 or later wide binary candidates, representing a seven-fold increase over the number currently known. These binaries are too wide to have been formed via the ejection mechanism. Finally, we found that 6% of spectroscopically confirmed M dwarfs are not included in the SDSS STAR catalog; they are misclassified as extended sources due to the presence of a nearby or partially resolved companion. The SLoWPoKES-II catalog is publicly available to the entire community on the World Wide Web via the Filtergraph data visualization portal.

  16. Reconstructing the outburst history of Eta Carinae from WFPC2 proper motions

    NASA Astrophysics Data System (ADS)

    Smith, Nathan

    2011-10-01

    The HST archive contains several epochs of WFPC2 images of the nebula around Eta Carinae taken over a 15-year timespan, although only the earliest few years of data have been analyzed and published. The fact that all these images were taken with the same instrument, with the same pixel sampling and field distortion, makes them an invaluable resource for accurately measuring the expanding ejecta. So far, analysis of a subset of the data {with only a few year baseline} has shown that Eta Car's nebula was ejected around the time of the Great Eruption in the 1840s, but the full 15-yr dataset has much greater untapped potential. Historical data show multiple peaks in the light curve during the 1840s eruption, possibly the result of violent stellar collisions in the eccentric binary system. Proper motions with the full 15-yr dataset will definitively show if one of these is associated with the main mass ejection. Older material outside the main bipolar nebula traces previous major outbursts of the star with no recorded historical observations. We propose an ambitious reduction and analysis of the complete WFPC2 imaging dataset of Eta Car. These data can reconstruct its violent mass-loss history over the past several thousand years. This will constrain the behavior and timescale of eruptive mass loss in pre-SN evolution. The existence of several epochs over a long timespan will date older parts of the nebula that have not yet been measured, and can even measure the deceleration of the ejecta for the first time, essential for understanding their shaping and shock excitation during the nebula's continuing hydrodynamic evolution.

  17. Documentation for the machine-readable version of the Lowell Proper Motion Survey northern hemisphere, the G numbered stars

    NASA Technical Reports Server (NTRS)

    Warren, W. H., Jr.

    1982-01-01

    Observed positions, proper motions, estimated photographic magnitudes and colors, and references to identifications in other catalogs are included. Photoelectric data on the UBV system are included for many stars, but no attempt was made to find all existing photometry. The machine-readable catalog is described.

  18. DISCOVERIES FROM A NEAR-INFRARED PROPER MOTION SURVEY USING MULTI-EPOCH TWO MICRON ALL-SKY SURVEY DATA

    SciTech Connect

    Kirkpatrick, J. Davy; Cutri, Roc M.; Looper, Dagny L.; Burgasser, Adam J.; Schurr, Steven D.; Cushing, Michael C.; Cruz, Kelle L.; Sweet, Anne C.; Knapp, Gillian R.; Barman, Travis S.; Bochanski, John J.; Roellig, Thomas L.; McLean, Ian S.; McGovern, Mark R.; Rice, Emily L.

    2010-09-15

    We have conducted a 4030 deg{sup 2} near-infrared proper motion survey using multi-epoch data from the Two Micron All-Sky Survey (2MASS). We find 2778 proper motion candidates, 647 of which are not listed in SIMBAD. After comparison to Digitized Sky Survey images, we find that 107 of our proper motion candidates lack counterparts at B, R, and I bands and are thus 2MASS-only detections. We present results of spectroscopic follow-up of 188 targets that include the infrared-only sources along with selected optical-counterpart sources with faint reduced proper motions or interesting colors. We also establish a set of near-infrared spectroscopic standards with which to anchor near-infrared classifications for our objects. Among the discoveries are six young field brown dwarfs, five 'red L' dwarfs, three L-type subdwarfs, twelve M-type subdwarfs, eight 'blue L' dwarfs, and several T dwarfs. We further refine the definitions of these exotic classes to aid future identification of similar objects. We examine their kinematics and find that both the 'blue L' and 'red L' dwarfs appear to be drawn from a relatively old population. This survey provides a glimpse of the kinds of research that will be possible through time-domain infrared projects such as the UKIDSS Large Area Survey, various VISTA surveys, and WISE, and also through z- or y-band enabled, multi-epoch surveys such as Pan-STARRS and LSST.

  19. Dynamics of a Type Ia Supernova Remnant: X-ray and Radio Proper Motions in Tycho's SNR

    NASA Astrophysics Data System (ADS)

    Williams, Brian J.; Blondin, John M.; Borkowski, Kazimierz J.; Chomiuk, Laura; Ghavamian, Parviz; Hewitt, John W.; Petre, Robert; Reynolds, Stephen P.

    2016-01-01

    We present results from new Chandra X-ray and JVLA radio observations of Tycho's supernova remnant, the remains of the supernova of 1572 A.D. The high spatial resolution of these instruments allows for accurate measurements of the proper motion of the forward shock in Tycho, with baselines now at 15 years for the X-ray data and 30 years for the radio. Type Ia SNe are of fundamental importance in astrophysics, yet the nature of their environments and progenitor systems is poorly understood. In a recent work, we have shown that theISM surrounding Tycho varies systematically in density by a factor of 5, with larger excursions in some locations. A substantial density variation is consistent with limited previous proper motion studies that have been done in radio and X-rays. Our expanded baseline measurements allow us to further explore the variations in the dynamics of the shock wave, which can also be used to localize the explosion site. Previous proper motion measurements, made over much shorter time baselines, have shown some discrepancies in the shockvelocity as measured in radio and X-rays. With our new, much improved data, we can compare proper motions in these two energy bands with much greater accuracy.

  20. Dynamical analysis of nearby clusters. Automated astrometry from the ground: precision proper motions over a wide field

    NASA Astrophysics Data System (ADS)

    Bouy, H.; Bertin, E.; Moraux, E.; Cuillandre, J.-C.; Bouvier, J.; Barrado, D.; Solano, E.; Bayo, A.

    2013-06-01

    Context. The kinematic properties of the different classes of objects in a given association hold important clues about the history of its members, and offer a unique opportunity to test the predictions of the various models of stellar formation and evolution. Aims: DANCe (standing for dynamical analysis of nearby clusters) is a survey program aimed at deriving a comprehensive and homogeneous census of the stellar and substellar content of a number of nearby (<1 kpc) young (<500 Myr) associations. Whenever possible, members will be identified based on their kinematics properties, ensuring little contamination from background and foreground sources. Otherwise, the dynamics of previously confirmed members will be studied using the proper motion measurements. We present here the method used to derive precise proper motion measurements, using the Pleiades cluster as a test bench. Methods: Combining deep wide-field multi-epoch panchromatic images obtained at various obervatories over up to 14 years, we derived accurate proper motions for the sources in the field of the survey. The datasets cover ≈80 square degrees, centered around the Seven Sisters. Results: Using new tools, we have computed a catalog of 6 116 907 unique sources, including proper motion measurements for 3 577 478 of them. The catalog covers the magnitude range between i = 12 ~ 24 mag, achieving a proper motion accuracy <1 mas y-1 for sources as faint as i = 22.5 mag. We estimate that our final accuracy reaches 0.3 mas yr-1 in the best cases, depending on magnitude, observing history, and the presence of reference extragalactic sources for the anchoring onto the ICRS. Based on observations obtained with MegaPrime/MegaCam, a joint project of CFHT and CEA/DAPNIA, at the Canada-France-Hawaii Telescope (CFHT) which is operated by the National Research Council (NRC) of Canada, the Institut National des Science de l'Univers of the Centre National de la Recherche Scientifique (CNRS) of France, and the

  1. Desktop Parallax and Proper Motion: A Laboratory Exercise on Astrometry of Asteroids from Project CLEA

    NASA Astrophysics Data System (ADS)

    Marschall, L. A.; Snyder, G. A.; Good, R. F.; Hayden, M. B.; Cooper, P. R.

    1998-12-01

    Students in introductory and advanced astronomy classes can now experience the process of discovering asteroids, can measure proper motions, and can actually see the parallax of real astronomical objects on the screen, using a new set of computer-based exercises from Project CLEA. The heart of the exercise is a sophisticated astrometry program "Astrometry of Asteroids", which is a restricted version of CLEA's research software "Tools for Astrometry" described elsewhere at this meeting. The program, as used in the teaching lab, allows students to read and display digital images, co-align pairs of images using designated reference stars, blink and identify moving objects on the pairs, compare images with charts produced from the HST Guide Star Catalog (GSC), and fit equatorial coordinates to the images using designated reference stars from the GSC. Complete technical manuals for the exercise are provided for the use of the instructor, and a set of digital images, in FITS format, is included for the exercise. A student manual is provided for an exercise in which students go through the step-by-step process of determining the tangential velocity of an asteroid. Students first examine a series of images of a near-earth asteroid taken over several hours, blinking pairs to identify the moving object. They next measure the equatorial coordinates on a half-dozen images, and from this calculate an angular velocity of the object. Finally, using a pair of images of the asteroid taken simultaneously at the National Undergraduate Research Observatory (NURO) and at Colgate University, they measure the parallax of the asteroid, and thus its distance, which enables them to convert the angular velocity into a tangential velocity. An optional set of 10 pairs of images is provided, some of which contain asteroids, so that students can try to "find the asteroid" for themselves. The software is extremely flexible, and though materials are provided for a self-contained exercise, teachers

  2. BVRIJHK photometry and proper motion analysis of NGC 6253 and the surrounding field

    NASA Astrophysics Data System (ADS)

    Montalto, M.; Piotto, G.; Desidera, S.; Platais, I.; Carraro, G.; Momany, Y.; de Marchi, F.; Recio-Blanco, A.

    2009-10-01

    Context: We present a photometric and astrometric catalog of 187 963 stars located in the field around the old super-metal-rich Galactic open cluster NGC 6253. The total field-of-view covered by the catalog is 34”×33”. In this field, we provide CCD BVRI photometry. For a smaller region close to the cluster's center, we also provide near-infrared JHK photometry. Aims: We analyze the properties of NGC 6253 by using our new photometric data and astrometric membership. Methods: In June 2004, we targeted the cluster during a 10 day multi-site campaign, which involved the MPG/ESO 2.2 m telescope with its wide-field imager and the Anglo-Australian 3.9 m telescope, equipped with the IRIS2 near-infrared imager. Archival CCD images of NGC 6253 were used to derive relative proper motions and to calculate the cluster membership probabilities. Results: We have refined the cluster's fundamental parameters, deriving (V_0-M_v)=11.15, E(B - V) = 0.15, E(V - I) = 0.25, E(V - J) = 0.50, and E(V - H) = 0.55. The color excess ratios obtained using both the optical and near infrared colors indicate a normal reddening law in the direction of NGC 6253. The age of NGC 6253 at 3.5 Gyr, determined from our best-fitting isochrone appears to be slightly older than the previous estimates. Finally, we estimated the binary fraction among the cluster members to be ~20%-30% and identified 11 blue straggler candidates. Based on observation made at the European Southern Observatory, La Silla, Chile and at the Anglo-Australian Observatory, Siding Spring, Australia. The catalog presented in this paper is 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/505/1129

  3. Hubble imaging of V1331 Cygni: proper motion study of its circumstellar structures

    NASA Astrophysics Data System (ADS)

    Choudhary, A.; Stecklum, B.; Linz, Hendrik

    2016-05-01

    Aims: The young star V1331 Cyg received previous attention because it is surrounded by an optical, arc-like reflection nebula. V1331 Cyg is commonly considered to be a candidate for an object that has undergone an FU-Ori (FUOR) outbreak in the past. This in turn could lead to a time-varying appearance of the dusty arcs that may be revealed by multi-epoch imaging. In particular, a radial colour analysis of the dust arcs can then be attempted to check whether the radial grain size distribution was modified by a previous FUOR wind. Methods: Second-epoch imaging of V1331 Cyg was obtained by us in 2009 using the Hubble Space Telescope (HST). By comparing this to archival HST data from 2000, we studied the time evolution of the circumstellar nebulae. After a point spread function subtraction using model point spread functions, we used customised routines to perform a proper motion analysis. The nebula expansion was derived by deconvolving and correlating the two-epoch radial brightness profiles. Additional data from other facilities - TLS, UKIDSS, Spitzer, and Herschel - were also incorporated to improve our understanding of the star in terms of environment, viewing angle, bipolar outflow length, and the FUOR phenomenon. Results: The outer dust arc is found to be expanding at ≈14.8 ± 3.6 km s-1 on average. The expansion velocity for the inner ring is less consistent, between 0.8 km s-1 and 3.0 km s-1. The derived radial colour profiles do not indicate a spatial separation of the dust grain sizes. The Herschel 160 μm images show for the first time thermal emission from dust probably residing in the outer arc. By viewing V1331 Cyg almost pole-on, the length of the bipolar outflow exceeds previous estimates by far. Conclusions: The outer arc expansion timescale is consistent with the implantation time of the CO torus, which supports the hypothesis of an outburst that occurred a few thousand years ago. The azimuthal colour variation of the outer arc is probably due to

  4. Spectrum and proper motion of a brown dwarf companion of the T Tauri star CoD-33̂7795

    NASA Astrophysics Data System (ADS)

    Neuhäuser, R.; Guenther, E. W.; Petr, M. G.; Brandner, W.; Huélamo, N.; Alves, J.

    2000-08-01

    We present optical and infrared spectra as well as the proper motion of an H=12 mag object 2'' off the ~ 5 mag brighter spectroscopic binary star CoD-33̂7795 (=TWA-5), a member of the TW Hya association of T Tauri stars at ~ 55 pc. It was suggested as companion candidate by Lowrance et al. (1999) and Webb et al. (1999), but neither a spectrum nor the proper motion of the faint object were available before. Our spectra taken with FORS2 and ISAAC at the ESO-VLT reveal that the companion candidate has spectral type M8.5 to M9. It shows strong Hα emission and weak Na I absorption, both indicative of a young age. The faint object is clearly detected and resolved in our optical and infrared images, with a FWHM of 0.18'' in the FORS2 image. The faint object's proper motion, based on two year epoch difference, is consistent with the proper motion of CoD-33̂7795 by 5 Gaussian σ significance. From three different theoretical pre-main sequence models, we estimate the companion mass to be between ~ 15 and 40 Mjup, assuming the distance and age of the primary. A slight offset between the VLT and HST images with an epoch difference of two years can be interpreted as orbital motion. The probability for chance alignment of such a late-type object that close to CoD-33̂7795 with the correct proper motion is below 7.10-9. Hence, the faint object is physically associated with CoD-33̂7795, the 4th brown dwarf companion around a normal star confirmed by both spectrum and proper motion, the first around a pre-main sequence star. Based on observations obtained at the European Southern Observatory, Cerro Paranal, partly from program 65.L-0144 and partly based on public data released from FORS2 technical observations at the VLT Kueyen telescope

  5. Optical-Ultraviolet Spectrum and Proper Motion of the Middle-aged Pulsar B1055-52

    NASA Astrophysics Data System (ADS)

    Mignani, R. P.; Pavlov, G. G.; Kargaltsev, O.

    2010-09-01

    PSR B1055-52 is a middle-aged (τ = 535 kyr) radio, X-ray, and γ-ray pulsar showing X-ray thermal emission from the neutron star (NS) surface. A candidate optical counterpart to PSR B1055-52 was proposed by Mignani and coworkers based on Hubble Space Telescope (HST) observations performed in 1996, in one spectral band only. We report on HST observations of this field carried out in 2008, in four spectral bands. The astrometric and photometric analyses of these data confirm the identification of the proposed candidate as the pulsar's optical counterpart. Similar to other middle-aged pulsars, its optical-UV spectrum can be described by the sum of a power-law (PLO) component (F_{ν} ∝ ν^{-α_O}), presumably emitted from the pulsar magnetosphere, and a Rayleigh-Jeans (RJ) component emitted from the NS surface. The spectral index of the PLO component, αO = 1.05 ± 0.34, is larger than for other pulsars with optical counterparts. The RJ component, with a brightness temperature T O = (0.66 ± 0.10) d 2 350 R -2 O,13 MK (where d 350 and R O,13 are the distance to the pulsar in units of 350 pc and the radius of the emitting area in units of 13 km, respectively), shows a factor of 4 excess with respect to the extrapolation of the X-ray thermal component into the UV-optical. This hints that the RJ component is emitted from a larger, colder area, and suggests that the distance to the pulsar is smaller than previously thought. From absolute astrometry of the HST images, we measured the pulsar coordinates with a position accuracy of 0farcs15. From comparison with previous observations, we measured the pulsar proper motion, μ = 42 ± 5 mas yr-1, which corresponds to a transverse velocity Vt = (70 ± 8) d 350 km s-1. Based on observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by AURA, Inc., under contract No. NAS 5-26555. Based on observations collected at the European Southern Observatory (ESO), La

  6. Upper plate absolute motion and slab-anchor force control on back-arc deformation

    NASA Astrophysics Data System (ADS)

    Heuret, A.; Lallemand, S.

    2003-04-01

    In order to test how the combined effects of overriding plate motion and trench migration can account for the variability of back-arc tectonic regimes, their "normal to the trench" absolute motion components and the strain regime of all oceanic subduction zones were compiled. Strain regime was estimated following Jarrard (1986), in a semiquantitative way. The upper plate absolute motion (Vup) is calculated in the hotspot HS3-NUVEL1A (Gripp and Gordon, 2002) reference frame and trench migration (Vt) from Vup, corrected from deformation rate of back-arc region, mainly given by GPS data. As slabs tend to sink because of their age-related-mass-excess relative to the surrounding mantle, it is generally assumed that most of the trenches have a spontaneous seaward motion (trench rollback). Ages at trench have thus also been compiled ( from Muller et al, 1997) to test a possible control of trench migration with slab age. Our values underline a high control of strain regime by Vup, but inconsistencies still remain with this single parameter. To account for all the observed deformations, trench migration is needed. There are more or less as much subduction zones with seaward Vt as landward ones, and, for 90% of subduction zones, Vt never reach 50 mm/y in the two directions. The expected relation between trench migration and slab age is far to be verified: landward trench migrations exist in many subduction zones, and, among them, many have old slabs. Several examples indicate that the slab tend to follow the trench migration and, so, to move transversely in the surrounding mantle. As a consequence, Vt is close to the "normal to the trench" slab migration and gives informations about the slab anchor force : slabs are not perfectly anchored but their possible motions appear to be limited. This 50 mm/y limitation of slab migration may provide new constraints on the poorly known slab-anchor force. No evidence of age related trench rollback have beeen found. It does not

  7. VizieR Online Data Catalog: Velocities and proper motions of Galactic Cepheids (Mel'nik+, 2015)

    NASA Astrophysics Data System (ADS)

    Mel'Nik, A. M.; Rautiainen, P.; Berdnikov, L. N.; Dambis, A. K.; Rastorguev, A. S.

    2015-01-01

    For every classical Cepheid we give its designation in the General Catalog of Variable Stars (GCVS) (Samus at al., 2007, Cat. B/gcvs) or in the All Sky Automated Survey (ASAS) (Pojmanski 2002, II/264), its type (see GCVS description), fundamental period PF, intensity-mean V-band magnitude , J2000 equatorial coordinates, Galactic coordinates l and b, and heliocentric distance r. Table 1 also gives the Cepheid line-of-sight velocities Vr (the so-called γ-velocities), their uncertainties e_Vr and the references (1-6) to the sources from which they are taken. The proper motions of Cepheids were adopted from the new reduction of Hipparcos data (ESA 1997, Cat. I/239) by van Leeuwen (2007, Cat. I/311). Table 1 presents proper motions pmRA and pmDE, their uncertainties epmRA and epmDE and the corresponding Hipparcos catalog number HIP. (1 data file).

  8. THIRD-EPOCH MAGELLANIC CLOUD PROPER MOTIONS. I. HUBBLE SPACE TELESCOPE/WFC3 DATA AND ORBIT IMPLICATIONS

    SciTech Connect

    Kallivayalil, Nitya; Van der Marel, Roeland P.; Anderson, Jay; Besla, Gurtina; Alcock, Charles

    2013-02-20

    We present proper motions for the Large and Small Magellanic Clouds (LMC and SMC) based on three epochs of Hubble Space Telescope data, spanning a {approx}7 yr baseline, and centered on fields with background QSOs. The first two epochs, the subject of past analyses, were obtained with ACS/HRC, and have been reanalyzed here. The new third epoch with WFC3/UVIS increases the time baseline and provides better control of systematics. The three-epoch data yield proper-motion random errors of only 1%-2% per field. For the LMC this is sufficient to constrain the internal proper-motion dynamics, as will be discussed in a separate paper. Here we focus on the implied center-of-mass proper motions: {mu} {sub W,LMC} = -1.910 {+-} 0.020 mas yr{sup -1}, {mu} {sub N,LMC} = 0.229 {+-} 0.047 mas yr{sup -1}, and {mu} {sub W,SMC} = -0.772 {+-} 0.063 mas yr{sup -1}, {mu} {sub N,SMC} = -1.117 {+-} 0.061 mas yr{sup -1}. We combine the results with a revised understanding of the solar motion in the Milky Way to derive Galactocentric velocities: v {sub tot,LMC} = 321 {+-} 24 km s{sup -1} and v {sub tot,SMC} = 217 {+-} 26 km s{sup -1}. Our proper-motion uncertainties are now dominated by limitations in our understanding of the internal kinematics and geometry of the Clouds, and our velocity uncertainties are dominated by distance errors. Orbit calculations for the Clouds around the Milky Way allow a range of orbital periods, depending on the uncertain masses of the Milky Way and LMC. Periods {approx}< 4 Gyr are ruled out, which poses a challenge for traditional Magellanic Stream models. First-infall orbits are preferred (as supported by other arguments as well) if one imposes the requirement that the LMC and SMC must have been a bound pair for at least several Gyr.

  9. DISTANCE AND PROPER MOTION MEASUREMENT OF THE RED SUPERGIANT, S PERSEI, WITH VLBI H{sub 2}O MASER ASTROMETRY

    SciTech Connect

    Asaki, Y.; Deguchi, S.; Imai, H.; Hachisuka, K.; Miyoshi, M.; Honma, M. E-mail: deguchi@nro.nao.ac.j E-mail: khachi@shao.ac.c E-mail: mareki.honma@nao.ac.j

    2010-09-20

    We have conducted Very Long Baseline Array phase-referencing monitoring of H{sub 2}O masers around the red supergiant, S Persei, for six years. We have fitted maser motions to a simple expanding-shell model with a common annual parallax and stellar proper motion, and obtained the annual parallax as 0.413 {+-} 0.017 mas and the stellar proper motion as (-0.49 {+-} 0.23 mas yr{sup -1}, -1.19 {+-} 0.20 mas yr{sup -1}) in right ascension and declination, respectively. The obtained annual parallax corresponds to the trigonometric distance of 2.42{sup +0.11}{sub -0.09} kpc. Assuming a Galactocentric distance of the Sun of 8.5 kpc, the circular rotational velocity of the local standard of rest at a distance of the Sun of 220 km s{sup -1}, and a flat Galactic rotation curve, S Persei is suggested to have a non-circular motion deviating from the Galactic circular rotation for 15 km s{sup -1}, which is mainly dominated by the anti-rotation direction component of 12.9 {+-} 2.9 km s{sup -1}. This red supergiant is thought to belong to the OB association, Per OB1, so that this non-circular motion is representative of a motion of the OB association in the Milky Way. This non-circular motion is somewhat larger than that explained by the standard density-wave theory for a spiral galaxy and is attributed to either a cluster shuffling of the OB association, or to non-linear interactions between non-stationary spiral arms and multi-phase interstellar media. The latter comes from a new view of a spiral arm formation in the Milky Way suggested by recent large N-body/smoothed particle hydrodynamics numerical simulations.

  10. A method for the correction of proper motions of stars around an extragalactic object in photographic astrometry

    NASA Astrophysics Data System (ADS)

    Ducourant, C.; Rapaport, M.

    1991-01-01

    A method is described to correct the proper motions of catalogue stars present on overlapping plates around a quasar. The local reference system defined by the adjusted catalogue appears closer to an inertial system than the original catalogue. First we present the method we developed: an overlap technique is applied to reduce simultaneously the measurements of the plates while using the presence of the quasar as a fixed point. The overlap treatment allows to take account of the a priori errors of the catalogue and to determine an estimation of these errors. We apply this method to a set of two old plates and one new plate containing AGK 3 stars and the quasar 3C 273. The resulting mini-catalogue of 26 AGK 3 stars has an accuracy of around 0".08 on positions and 0.005 arcsec yr-1 on proper motions. Our method achieved an improvement of a factor 1.7 of the precision of the catalogue data. The estimates of the quasar's proper motion components obtained by separate reduction of each exposure using the AGK 3 data were μα = -0.007 arcsec yr-1 and μδ = -0.010 arcsec yr-1. The estimates become μα = -0.0002 arcsec yr-1 and μδ = -0.0002 arcsec yr-1 if the adjusted mini-catalogue is used.

  11. The collimated outflows of the planetary nebula Hu 1-2: proper motion and radial velocity measurements

    NASA Astrophysics Data System (ADS)

    Miranda, L. F.; Blanco, M.; Guerrero, M. A.; Riera, A.

    2012-04-01

    Hu 1-2 is a planetary nebula that contains an isolated knot located north-west of the main nebula, which could be related to a collimated outflow. We present a subarcsecond Hα+[N II] image and a high-resolution, long-slit spectrum of Hu 1-2 that allow us to identify the south-eastern counterpart of the north-western knot and to establish their high-velocity (>340 km s-1), collimated bipolar outflow nature. The detection of the north-western knot in Palomar Observatory Sky Atlas (POSS) red plates allows us to carry out a proper motion analysis by combining three POSS red plates and two narrow-band Hα+[N II] CCD images, with a time baseline of ≃57 yr. A proper motion of 20 ± 6 mas yr-1 along position angle 312°± 15° and a dynamical age of 1375? yr are obtained for the bipolar outflow. The measured proper motion and the spatio-kinematical properties of the bipolar outflow yield a lower limit of 2.7 kpc for the distance to Hu 1-2. The Andalucia Faint Object Spectrograph and Camera (ALFOSC) is provided by the Instituto de Astrofísica de Andalucía (IAA) under a joint agreement with the University of Copenhagen and NOTSA. The IACUB uncrossed echelle spectrograph was built in a collaboration between the IAC and the Queen's University of Belfast.

  12. PROPER MOTIONS AND ORIGINS OF AXP 1E 2259+586 AND AXP 4U 0142+61

    SciTech Connect

    Tendulkar, Shriharsh P.; Kulkarni, Shrinivas R.; Cameron, P. Brian E-mail: srk@astro.caltech.edu

    2013-07-20

    Using high-resolution NIR images supported by laser guide star adaptive optics from the Keck II telescope from 2005 to 2012, we have measured the proper motions of two anomalous X-ray pulsars, AXP 1E 2259+586 and AXP 4U 0142+61. The proper motion of AXP 1E 2259+586 in the sky frame is ({mu}{sub {alpha}}, {mu}{sub {delta}}) = (- 6.4 {+-} 0.6, -2.3 {+-} 0.6) mas yr{sup -1} and that of AXP 4U 0142+61 is ({mu}{sub {alpha}}, {mu}{sub {delta}}) = (- 4.1 {+-} 1, 1.9 {+-} 1) mas yr{sup -1}. After correcting for the velocity of the progenitors, we calculate the tangential ejection velocities of the magnetars to be 157 {+-} 17 km s{sup -1} and 102 {+-} 26 km s{sup -1} respectively. The proper motion vector of AXP 1E 2259+586 is directed away from the putative center of the supernova remnant CTB 109 that has long been proposed to be associated with AXP 1E 2259+586. This is significant evidence for linking the pulsar with CTB 109. We comment on the possible movement of CTB 109 after the explosion. We narrow the search cone for the birthsite or remnant of AXP 4U 0142+61 to an opening angle of 24 Degree-Sign . However, we are unable to find any suitable association.

  13. "New Proper Motion Measurements of the Superluminal Velocities in the M87 Optical Jet with HST"

    NASA Astrophysics Data System (ADS)

    Meyer, Eileen T.; Sparks, W. B.; Biretta, J. A.; Sohn, S.; Anderson, J.; Van Der Marel, R. P.; Norman, C. A.; Nakamura, M.

    2014-01-01

    Using over 13 years of archival HST observations of the relativistic jet in the archetypal radio galaxy M87, we have produced astrometric speed measurements of the optically bright synchrotron emitting plasma components in the jet with unprecedented accuracy. Building on previous work showing the superluminal nature of the jet in the optical, we have found that the jet motion is incredibly complex, with both transverse motions and flux variations which can be seen very clearly by eye in the timeseries of deep exposures. These observations of M87 provide us with a unique dataset with which to refine theoretical models of the largescale jet structure, potentially addressing open questions such as the jet collimation mechanism, bulk acceleration and deceleration in the jet, and the presence of a helical structure. I will also present very recent results using data from the HST archive on the optical counterjet and nuclear regions of M87 and discuss the larger implications of these detailed studies of one of the most nearby AGN jets.

  14. Documentation for the machine-readable version of the Lowell Proper Motion Survey, Northern Hemisphere, the G numbered stars

    NASA Technical Reports Server (NTRS)

    Warren, W. H., Jr.

    1983-01-01

    This catalog contains a summary of many individual papers published in the Lowell Observatory Bulletins in the years 1958 to 1970. The data in the machine-readable version include observed positions, proper motions, estimated photographic magnitudes and colors, and references to identifications in other catalogs. Photoelectric data on the UBV system are included for many stars, but no attempt was made to find all existing photometry. The machine version contains all data of the published catalog, except the Lowell Bulletin numbers where finding charts can be found. A separate file contains the notes published in the original catalog.

  15. Estimating object proper motion using optical flow, kinematics, and depth information.

    PubMed

    Schmüdderich, Jens; Willert, Volker; Eggert, Julian; Rebhan, Sven; Goerick, Christian; Sagerer, Gerhard; Körner, Edgar

    2008-08-01

    For the interaction of a mobile robot with a dynamic environment, the estimation of object motion is desired while the robot is walking and/or turning its head. In this paper, we describe a system which manages this task by combining depth from a stereo camera and computation of the camera movement from robot kinematics in order to stabilize the camera images. Moving objects are detected by applying optical flow to the stabilized images followed by a filtering method, which incorporates both prior knowledge about the accuracy of the measurement and the uncertainties of the measurement process itself. The efficiency of this system is demonstrated in a dynamic real-world scenario with a walking humanoid robot. PMID:18632403

  16. Relegation of the proper rotation in the orbital-attitude motion of a spacecraft

    NASA Astrophysics Data System (ADS)

    Arribas, Mercedes; Elipe, Antonio

    An analytical approach is taken to study the attitude of a spacecraft on an orbit around a planet assimilated to a mass point. In the Hamiltonian representing this dynamical system, we identify the principal term (of order 0) as made of two parts: the part describing the motion of the center of mass of the satellite about the planet is expressed in terms of the Whittaker variables, and the part accounting for the rotation of the satellite about its center of mass in the absence of external forces which is expressed in terms of the Serret-Andoyer variables. We propose to build a Lie transformation to remove the angle g from the potential of the perturbation by applying the 'relegation of the node' technique.

  17. Absolute plate motion of Africa around Hawaii-Emperor bend time

    NASA Astrophysics Data System (ADS)

    Maher, S. M.; Wessel, P.; Müller, R. D.; Williams, S. E.; Harada, Y.

    2015-06-01

    Numerous regional plate reorganizations and the coeval ages of the Hawaiian Emperor bend (HEB) and Louisville bend of 50-47 Ma have been interpreted as a possible global tectonic plate reorganization at ˜chron 21 (47.9 Ma). Yet for a truly global event we would expect a contemporaneous change in Africa absolute plate motion (APM) reflected by physical evidence distributed on the Africa Plate. This evidence has been postulated to take the form of the Réunion-Mascarene bend which exhibits many HEB-like features, such as a large angular change close to ˜chron 21. However, the Réunion hotspot trail has recently been interpreted as a sequence of continental fragments with incidental hotspot volcanism. Here we show that the alternative Réunion-Mascarene Plateau trail can also satisfy the age progressions and geometry of other hotspot trails on the Africa Plate. The implied motion, suggesting a pivoting of Africa from 67 to 50 Ma, could explain the apparent bifurcation of the Tristan hotspot chain, the age reversals seen along the Walvis Ridge, the sharp curve of the Canary trail, and the diffuse nature of the St. Helena chain. To test this hypothesis further we made a new Africa APM model that extends back to ˜80 Ma using a modified version of the Hybrid Polygonal Finite Rotation Method. This method uses seamount chains and their associated hotspots as geometric constraints for the model, and seamount age dates to determine APM through time. While this model successfully explains many of the volcanic features, it implies an unrealistically fast global lithospheric net rotation, as well as improbable APM trajectories for many other plates, including the Americas, Eurasia and Australia. We contrast this speculative model with a more conventional model in which the Mascarene Plateau is excluded in favour of the Chagos-Laccadive Ridge rotated into the Africa reference frame. This second model implies more realistic net lithospheric rotation and far-field APMs, but

  18. High-precision Radio and Infrared Astrometry of LSPM J1314+1320AB. I. Parallax, Proper Motions, and Limits on Planets

    NASA Astrophysics Data System (ADS)

    Forbrich, Jan; Dupuy, Trent J.; Reid, Mark J.; Berger, Edo; Rizzuto, Aaron; Mann, Andrew W.; Liu, Michael C.; Aller, Kimberly; Kraus, Adam L.

    2016-08-01

    We present multi-epoch astrometric radio observations with the Very Long Baseline Array (VLBA) of the young ultracool-dwarf binary LSPM J1314+1320AB. The radio emission comes from the secondary star. Combining the VLBA data with Keck near-infrared adaptive-optics observations of both components, a full astrometric fit of parallax (π abs = 57.975 ± 0.045 mas, corresponding to a distance of d = 17.249 ± 0.013 pc), proper motion (μ αcos δ = ‑247.99 ± 0.10 mas yr‑1, μ δ = ‑183.58 ± 0.22 mas yr‑1), and orbital motion is obtained. Despite the fact that the two components have nearly identical masses to within ±2%, the secondary’s radio emission exceeds that of the primary by a factor of ≳30, suggesting a difference in stellar rotation history, which could result in different magnetic field configurations. Alternatively, the emission could be anisotropic and beamed toward us for the secondary but not for the primary. Using only reflex motion, we exclude planets of mass 0.7–10 M jup with orbital periods of 600–10 days, respectively. Additionally, we use the full orbital solution of the binary to derive an upper limit for the semimajor axis of 0.23 au for stable planetary orbits within this system. These limits cover a parameter space that is inaccessible with, and complementary to, near-infrared radial velocity surveys of ultracool dwarfs. Our absolute astrometry will constitute an important test for the astrometric calibration of Gaia.

  19. Mean positions and proper motions of 224 stars based on PZT observations at Ondrejov in 1973-1986

    NASA Astrophysics Data System (ADS)

    Vondrak, J.

    1988-05-01

    The third improvement of the positions and proper motions for the Ondřejov PZT star list is based solely on PZT observations in the interval 1973 - 1986. Within this period more than 44 thousand star transits on 1546 nights were observed. The mean epoch of the resulting catalogue PZT 86 is 1981.56, the average standard errors in right ascension and declination, referred to this epoch, are equal to ±0.0015s and ±0.017arcsec, respectively. The proper motions in right ascension and declination were obtained with an accuracy characterized by the average standard errors of ±0.051scy-1 and ±0.57arcseccy-1, which will cause the standard errors in position to increase to ±0.0096s and ±0.106arcsec by the end of the century. The comparison of the new catalogue with the preceding two (PZT 78 and PZT 83) and AGK 3 reveal important systematic errors in AGK 3 that grow with time.

  20. Mean positions and proper motions of 305 stars obtained from the combination of PZT observations at Ondrejov with AGK positions

    NASA Astrophysics Data System (ADS)

    Ron, C.; Vondrak, J.

    1985-09-01

    The observations of 305 stars made in the period from 1973 to 1983 with the PZT at Ondřejov were combined with the positions of the same stars in the catalogues AGK 2 and AGK 3 in order to obtain their mean positions and proper motions. Within the period in question more than 32 thousand star transits on 1140 nights were observed with the PZT; the average mean errors in right ascension and declination of a star that was observed throughout the whole period are ±0.0019s and ±0.020arcsec in the epoch around 1979 and they will increase to ±0.0055s and ±0.059arcsec in 2000. The proper motions in right ascension and declination are derived with average mean errors of ±0.024scy-1 and ±0.26arcseccy-1. The new catalogue has been used regularly to reduce PZT observations at Ondřejov since the beginning of 1985.

  1. A bag of tricks: Using proper motions of Galactic stars to identify the Hercules ultra-faint dwarf galaxy members

    NASA Astrophysics Data System (ADS)

    Fabrizio, M.; Raimondo, G.; Brocato, E.; Bellini, A.; Libralato, M.; Testa, V.; Cantiello, M.; Musella, I.; Clementini, G.; Carini, R.; Marconi, M.; Piotto, G.; Ripepi, V.; Buonanno, R.; Sani, E.; Speziali, R.

    2014-10-01

    Context. Discovered in the last decade as overdensities of resolved stars, the ultra-faint dwarfs (UFDs) are among the least luminous, most dark-matter dominated, and most metal-poor galaxies known today. They appear as sparse, loose objects with high mass-to-light ratios. Hercules is the prototype of the UFD galaxies. To date, there are still no firm constraints on its total luminosity due to the difficulty of disentangling Hercules bona-fide stars from the severe Galactic field contamination. Aims: To better constrain Hercules properties, we aim at removing foreground and background contaminants in the galaxy field using the proper motions of the Milky Way stars and the colour-colour diagram. Methods: We have obtained images of Hercules in the rSloan , BBessel and Uspec bands with the Large Binocular Telescope (LBT) and LBC-BIN mode capabilities. The rSloan new dataset combined with data from the LBT archive span a time baseline of about 5 yr, allowing us to measure proper motions of stars in the Hercules direction for the first time. The Uspec data along with existing LBT photometry allowed us to use colour-colour diagram to further remove the field contamination. Results: Thanks to a highly-accurate procedure to derive the rSloan -filter geometric distortion solution for the LBC-red, we were able to measure stellar relative proper motions to a precision of better than 5 mas yr-1 down to rSloan≃ 22 mag and disentangle a significant fraction (>90%) of Milky Way contaminants. We ended up with a sample of 528 sources distributed over a large portion of the galaxy body (~0.12 deg2). Of these sources, 171 turned out to be background galaxies and additional foreground stars from the analysis of the Uspec - BBessel vs. BBessel - rSloan colour-colour diagram. This leaves us with a sample of 357 likely members of the Hercules UFD. We compared the cleaned colour-magnitude diagram (CMD) with evolutionary models and synthetic CMDs, confirming the presence in Hercules of

  2. Trigonometric distance and proper motion of IRAS 20056+3350: a massive star-forming region on the solar circle

    SciTech Connect

    Burns, Ross A.; Handa, Toshihiro; Omodaka, Toshihiro; Nakagawa, Akiharu; Nakanishi, Hiroyuki; Nagayama, Takumi; Hayashi, Masahiko; Shizugami, Makoto

    2014-12-10

    We report our measurement of the trigonometric distance and proper motion of IRAS 20056+3350, obtained from the annual parallax of H{sub 2}O masers. Our distance of D=4.69{sub −0.51}{sup +0.65} kpc, which is 2.8 times larger than the near kinematic distance adopted in the literature, places IRAS 20056+3350 at the leading tip of the Local arm and proximal to the solar circle. Using our distance, we reevaluate past observations to reveal IRAS 20056+3350 as a site of massive star formation at a young stage of evolution. This result is consistent with the spectral energy distribution of the source evaluated with published photometric data from UKIDSS, WISE, AKARI, IRAS, and the submillimeter continuum. Both analytical approaches reveal the luminosity of the region to be 2.4 × 10{sup 4} L {sub ☉}, and suggest that IRAS 20056+3350 is forming an embedded star of ≥16 M {sub ☉}. We estimated the proper motion of IRAS 20056+3350 to be (μ{sub α}cos δ, μ{sub δ}) = (–2.62 ± 0.33, –5.65 ± 0.52) mas yr{sup –1} from the group motion of H{sub 2}O masers, and use our results to estimate the angular velocity of Galactic rotation at the Galactocentric distance of the Sun, Ω{sub 0} = 29.75 ± 2.29 km s{sup –1} kpc{sup –1}, which is consistent with the values obtained for other tangent point and solar circle objects.

  3. New high proper motion stars with declinations between -5(deg) and -30(deg) , and right ascensions between 13h 30m and 24h

    NASA Astrophysics Data System (ADS)

    Wroblewski, H.; Costa, E.

    1999-10-01

    Proper motions, positions, finding charts and magnitudes are given for 293 newly discovered stars with proper motions larger than 0.15 arcsec/year. They are located between -5(deg) and -30(deg) in declination, and 13h 30m and 24h in right ascension. Their blue photographic magnitudes range from approximately 13.0 to 18.5. Six stars of the above sample have proper motions larger than 0.4 (0.401 to 0.534) arcsec/year. An estimated precision level between 7 and 13 mas/year was achieved for the proper motions. Table~2 is only available in electronic form at the CDS via anonymous ftp 130.79.128.5 or http://cdsweb.u-strasbg.fr/Abstract.html and figures~2 are available in the on-line edition of the journal at http://www.edpsciences.com

  4. Proper Motions of the Outer Knots of the HH 80/81/80N Radio-jet

    NASA Astrophysics Data System (ADS)

    Masqué, Josep M.; Rodríguez, Luis F.; Araudo, Anabella; Estalella, Robert; Carrasco-González, Carlos; Anglada, Guillem; Girart, Josep M.; Osorio, Mayra

    2015-11-01

    The radio-knots of the Herbig-Haro (HH) 80/81/80N jet extend from the HH 80 object to the recently discovered Source 34 and has a total projected jet size of 10.3 pc, constituting the largest collimated radio-jet system known so far. It is powered by the bright infrared source IRAS 18162-2048 associated with a massive young stellar object. We report 6 cm JVLA observations that, compared with previous 6 cm VLA observations carried out in 1989, allow us to derive proper motions of the HH 80, HH 81, and HH 80N radio knots located about 2.5 pc away in projection from the powering source. For the first time, we measure proper motions of the optically obscured HH 80N object providing evidence that this knot, along with HH 81 and HH 80 are associated with the same radio-jet. We also confirm the presence of Source 34, located further north of HH 80N, previously proposed to belong to the jet.We derived that the tangential velocity of HH 80N is 260 km s-1 and has a direction in agreement with the expected direction of a ballistic precessing jet. The HH 80 and HH 81 objects have tangential velocities of 350 and 220 km s-1, respectively, but their directions are somewhat deviated from the expected jet path. The velocities of the HH objects studied in this work are significantly lower than those derived for the radio knots of the jet close to the powering source (600-1400 km s-1) suggesting that the jet is slowing down due to a strong interaction with the ambient medium. As a result, since HH 80 and HH 81 are located near the edge of the cloud, the inhomogeneous and low density medium may contribute to skew the direction of their determined proper motions. The HH 80 and HH 80N emission at 6 cm is, at least in part, probably synchrotron radiation produced by relativistic electrons in a magnetic field of 1 mG. If these electrons are accelerated in a reverse adiabatic shock, we estimate a jet total density of ≲1000 cm-3. All of these features are consistent with a jet emanating

  5. Cluster membership probabilities from proper motions and multi-wavelength photometric catalogues. I. Method and application to the Pleiades cluster

    NASA Astrophysics Data System (ADS)

    Sarro, L. M.; Bouy, H.; Berihuete, A.; Bertin, E.; Moraux, E.; Bouvier, J.; Cuillandre, J.-C.; Barrado, D.; Solano, E.

    2014-03-01

    Context. With the advent of deep wide surveys, large photometric and astrometric catalogues of literally all nearby clusters and associations have been produced. The unprecedented accuracy and sensitivity of these data sets and their broad spatial, temporal and wavelength coverage make obsolete the classical membership selection methods that were based on a handful of colours and luminosities. We present a new technique designed to take full advantage of the high dimensionality (photometric, astrometric, temporal) of such a survey to derive self-consistent and robust membership probabilities of the Pleiades cluster. Aims: We aim at developing a methodology to infer membership probabilities to the Pleiades cluster from the DANCe multidimensional astro-photometric data set in a consistent way throughout the entire derivation. The determination of the membership probabilities has to be applicable to censored data and must incorporate the measurement uncertainties into the inference procedure. Methods: We use Bayes' theorem and a curvilinear forward model for the likelihood of the measurements of cluster members in the colour-magnitude space, to infer posterior membership probabilities. The distribution of the cluster members proper motions and the distribution of contaminants in the full multidimensional astro-photometric space is modelled with a mixture-of-Gaussians likelihood. Results: We analyse several representation spaces composed of the proper motions plus a subset of the available magnitudes and colour indices. We select two prominent representation spaces composed of variables selected using feature relevance determination techniques based in Random Forests, and analyse the resulting samples of high probability candidates. We consistently find lists of high probability (p > 0.9975) candidates with ≈1000 sources, 4 to 5 times more than obtained in the most recent astro-photometric studies of the cluster. Conclusions: Multidimensional data sets require

  6. Proper motions and CCD-photometry of stars in the region of the open cluster NGC 1513

    NASA Astrophysics Data System (ADS)

    Frolov, V. N.; Jilinski, E. G.; Ananjevskaja, J. K.; Poljakov, E. V.; Bronnikova, N. M.; Gorshanov, D. L.

    2002-12-01

    The results of astrometric and photometric investigations of the poorly studied open cluster NGC 1513 are presented. The proper motions of 333 stars with a root-mean-square error of 1.9;mas yr-1 were obtained by means of the automated measuring complex ``Fantasy''. Eight astrometric plates covering the time interval of 101 years were measured and a total of 141 astrometric cluster members identified. BV CCD-photometry was obtained for stars in an area 17arcminx 17arcmin centered on the cluster. Altogether 33 stars were considered to be cluster members with high reliability by two criteria. The estimated age of NGC 1513 is 2.54x 108 years. 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/396/125.

  7. THE PROPER MOTION OF PSR J1550-5418 MEASURED WITH VLBI: A SECOND MAGNETAR VELOCITY MEASUREMENT

    SciTech Connect

    Deller, A. T.; Camilo, F.; Halpern, J. P.; Reynolds, J. E.

    2012-03-20

    The formation mechanism of neutron stars with extremely large magnetic field strengths (magnetars) remains unclear. Some formation scenarios predict that magnetars should be born with extremely high space velocities, >1000 km s{sup -1}. Using the Long Baseline Array in Australia, we have measured the proper motion of the intermittently radio-bright magnetar PSR J1550-5418 (1E 1547.0-5408): {mu} = 9.2 {+-} 0.6 mas yr{sup -1}. For a likely distance of 6 {+-} 2 kpc, the implied transverse velocity is 280{sup +130}{sub -120} km s{sup -1} after correcting for Galactic rotation. Along with the Almost-Equal-To 200 km s{sup -1} transverse velocity measured for the magnetar XTE J1810-197, this result suggests that formation pathways producing large magnetic fields do not require very large birth kicks.

  8. Deep study on the proper motion and collimated tail of the oldish PSR J2055+2539

    NASA Astrophysics Data System (ADS)

    Marelli, Martino

    2014-09-01

    The bright, radio-quiet, and possibly near, J2055+2539 is the less energetic non-recycled pulsar emitting in gamma-rays. In X-rays we found the faint, pulsating counterpart. Two tails of X-ray emission have been discovered protruding from the pulsar forming an angle of about 150deg. These tails are long - 13' and 4' - bright - 10 and 2 times the pulsar luminosity - and extremely collimated - the longest one is 5 to 20'' wide. These characteristics make J2055 tails the best test for all the nebular emission models, making it a better case than fainter Guitar nebula. Two Chandra observations at different epochs are requested in order to a) find the pulsar proper motion, with a possible alignment with one of the tails, and b) study the shape and low-scale structures of the nebulae.

  9. The kinematical analysis of proper motions and radial velocities of stars by means of the vector spherical harmonics

    NASA Astrophysics Data System (ADS)

    Tsvetkov, A.; Vityazev, . V.; , Kumkova I. I.

    2009-09-01

    The paper describes the application of the 3-D vector spherical harmonics (henceforth VSH) to the investigation of stellar kinematics. The VSH technique is suitable for present and future catalogues which contain all three components of velocity vector: proper motions and radial velocities. In general, the VSH allows to detect all the systematic components in the stellar velocity field and does not depend on any model. If some physical model is used, the VSH not only determines the parameters of the model, but detects the systematic components which are beyond the model. The application of the VSH to the Hipparcos data complimented with radial velocities discovers the systematic components which are beyond the linear Ogorodnikov-milne model.

  10. The proper motion of the nearby radio-quiet gamma-ray pulsar PSR J0357+3205

    NASA Astrophysics Data System (ADS)

    De Luca, Andrea

    2011-09-01

    PSR J0357+32 is a radio-quiet gamma-ray pulsar detected by the Fermi-LAT. The relatively high gamma-ray flux with respect to the modest rotational energy loss rate suggests that PSR J0357+32 is relatively close-by, probably at ≈ 500 pc. An observation of PSR J0357+32 with Chandra in AO11 allowed us to detect the X-ray counterpart of the pulsar. Most interesting, Chandra data unveiled the existence of a huge (9 arcmin long) extended feature apparently protruding from the pulsar. The most natural interpretation of the feature - a bow-shock pulsar wind nebula - is challenged by its very unusual phenomenology and by energetic arguments.A measure of the pulsar proper motion with Chandra could easily clarify the nature of its puzzling X-ray tail.

  11. Cygnus OB2 DANCe: A high-precision proper motion study of the Cygnus OB2 association

    NASA Astrophysics Data System (ADS)

    Wright, Nicholas J.; Bouy, Herve; Drew, Janet E.; Sarro, Luis Manuel; Bertin, Emmanuel; Cuillandre, Jean-Charles; Barrado, David

    2016-08-01

    We present a high-precision proper motion study of 873 X-ray and spectroscopically selected stars in the massive OB association Cygnus OB2 as part of the DANCe project. These were calculated from images spanning a 15 yr baseline and have typical precisions <1 mas yr-1. We calculate the velocity dispersion in the two axes to be σ _α (c) = 13.0^{+0.8}_{-0.7} and σ _δ (c) = 9.1^{+0.5}_{-0.5} km s-1, using a two-component, two-dimensional model that takes into account the uncertainties on the measurements. This gives a three-dimensional velocity dispersion of σ3D = 17.8 ± 0.6 km s-1 implying a virial mass significantly larger than the observed stellar mass, confirming that the association is gravitationally unbound. The association appears to be dynamically unevolved, as evidenced by considerable kinematic substructure, non-isotropic velocity dispersions and a lack of energy equipartition. The proper motions show no evidence for a global expansion pattern, with approximately the same amount of kinetic energy in expansion as there is in contraction, which argues against the association being an expanded star cluster disrupted by process such as residual gas expulsion or tidal heating. The kinematic substructures, which appear to be close to virial equilibrium and have typical masses of 40-400 M⊙, also do not appear to have been affected by the expulsion of the residual gas. We conclude that Cyg OB2 was most likely born highly substructured and globally unbound, with the individual subgroups born in (or close to) virial equilibrium, and that the OB association has not experienced significant dynamical evolution since then.

  12. The Origin of the Metal-Poor Common Proper Motion Pair HD 134439/134440: Insights from New Elemental Abundances

    NASA Astrophysics Data System (ADS)

    Chen, Yu; King, Jeremy R.; Boesgaard, Ann M.

    2014-11-01

    The low [α/Fe] ratio in the metal-poor ([Fe/H] ~ -1.50) common proper motion pair HD 134439 and HD 134440 has been variously attributed to chemical evolution in an extragalactic environment with an irregular star formation history, planetesimal accretion, and formation in an environment with an unusually high dust-to-gas ratio. We explore these various putative origins using CNO, Be, Ag, and Eu abundances derived from high-resolution near-UV Keck/HIRES spectroscopy. While we confirm a previously suggested correlation between elemental abundance ratios and condensation temperature at the 95% confidence level, these ratios lie within the continuum of values manifested by extant dSph data. We argue that the most plausible origin of our stars' distinctive abundance distribution relative to the Galactic halo field is formation in an environment chemically dominated by products of Type II SN of low progenitor mass; such a progenitor mass bias has been previously suggested as an explanation of low α-element ratios of dSph stars. The proper motion pair's heavy-to-light n-capture element ratio, which is >=0.3-0.5 dex lower than in the Galactic halo field and dSph stars, is discussed in the context of the truncated r-process, phenomenological n-capture production models, and α-rich freezeout in a high neutron excess environment; the latter simultaneously provides an attractive explanation of the difference in [Ca, Ti/O, Mg, Si] ratio in HD 134439/134440 compared to in situ dSph stars.

  13. Cygnus OB2 DANCe: A high-precision proper motion study of the Cygnus OB2 association

    NASA Astrophysics Data System (ADS)

    Wright, Nicholas J.; Bouy, Herve; Drew, Janet E.; Sarro, Luis Manuel; Bertin, Emmanuel; Cuillandre, Jean-Charles; Barrado, David

    2016-08-01

    We present a high-precision proper motion study of 873 X-ray and spectroscopically selected stars in the massive OB association Cygnus OB2 as part of the DANCe project. These were calculated from images spanning a 15 year baseline and have typical precisions < 1 mas/yr. We calculate the velocity dispersion in the two axes to be $\\sigma_\\alpha(c) = 13.0^{+0.8}_{-0.7}$ and $\\sigma_\\delta(c) = 9.1^{+0.5}_{-0.5}$ km/s, using a 2-component, 2-dimensional model that takes into account the uncertainties on the measurements. This gives a 3-dimensional velocity dispersion of $\\sigma_{3D} = 17.8 \\pm 0.6$ km/s implying a virial mass significantly larger than the observed stellar mass, confirming that the association is gravitationally unbound. The association appears to be dynamically unevolved, as evidenced by considerable kinematic substructure, non-isotropic velocity dispersions and a lack of energy equipartition. The proper motions show no evidence for a global expansion pattern, with approximately the same amount of kinetic energy in expansion as there is in contraction, which argues against the association being an expanded star cluster disrupted by process such as residual gas expulsion or tidal heating. The kinematic substructures, which appear to be close to virial equilibrium and have typical masses of 40-400 M$_\\odot$, also do not appear to have been affected by the expulsion of the residual gas. We conclude that Cyg OB2 was most likely born highly substructured and globally unbound, with the individual subgroups born in (or close to) virial equilibrium, and that the OB association has not experienced significant dynamical evolution since then.

  14. Dynamics of intraoceanic subduction initiation: 2. Suprasubduction zone ophiolite formation and metamorphic sole exhumation in context of absolute plate motions

    NASA Astrophysics Data System (ADS)

    van Hinsbergen, Douwe J. J.; Peters, Kalijn; Maffione, Marco; Spakman, Wim; Guilmette, Carl; Thieulot, Cedric; Plümper, Oliver; Gürer, Derya; Brouwer, Fraukje M.; Aldanmaz, Ercan; Kaymakcı, Nuretdin

    2015-06-01

    Analyzing subduction initiation is key for understanding the coupling between plate tectonics and the underlying mantle. Here we focus on suprasubduction zone (SSZ) ophiolites and how their formation links to intraoceanic subduction initiation in an absolute plate motion frame. SSZ ophiolites form the majority of exposed oceanic lithosphere fragments and are widely recognized to have formed during intraoceanic subduction initiation. Structural, petrological, geochemical, and plate kinematic constraints on their kinematic evolution show that SSZ crust forms at fore-arc spreading centers at the expense of a mantle wedge, thereby flattening the nascent slab. This leads to the typical inverted pressure gradients found in metamorphic soles that form at the subduction plate contact below and during SSZ crust crystallization. Former spreading centers are preserved in forearcs when subduction initiates along transform faults or off-ridge oceanic detachments. We show how these are reactivated when subduction initiates in the absolute plate motion direction of the inverting weakness zone. Upon inception of slab pull due to, e.g., eclogitization, the sole is separated from the slab, remains welded to the thinned overriding plate lithosphere, and can become intruded by mafic dikes upon asthenospheric influx into the mantle wedge. We propound that most ophiolites thus formed under special geodynamic circumstances and may not be representative of normal oceanic crust. Our study highlights how far-field geodynamic processes and absolute plate motions may force intraoceanic subduction initiation as key toward advancing our understanding of the entire plate tectonic cycle.

  15. ACS detection of sub-stellar companions around Vega, Fomalhaut and beta Pic via parallax & proper motion

    NASA Astrophysics Data System (ADS)

    Kalas, Paul

    2003-07-01

    The first visible light coronagraph on HST provides contrast ratios near very bright stars that are unparalleled by ground-based observations. Vega, Fomalhaut and Beta Pictoris have dusty debris disks with structure thought to originate from the presence of yet-undetected, substellar companions. The detection of substellar companions is possible with the ACS HRC coronagraph if observations are made in two epochs. Here we propose to image Vega in two epochs within Cycle 12. We argue that in a few months interval, the sky plane motion of any companions due to parallax and proper motion is large relative to the HRC astrometric uncertainties. Likewise, we propose to obtain a second epoch image of Beta Pic and Fomalhaut within Cycle 12 to complement the single epoch imaging of the GTO program. Because Vega, Fomalhaut and Beta Pictoris are young and nearby, this imaging campaign will be sensitive to brown dwarfs and massive extrasolar giant planets at their predicted locations 40-60 AU projected radius from each star. Either positive or negative results for each system will be used to constrain the physical characteristics of massive objects hypothesized to cause the observed disk asymmetries.

  16. The World Stress Map Database Release 2016 - Global Crustal Stress Pattern vs. Absolute Plate Motion

    NASA Astrophysics Data System (ADS)

    Heidbach, Oliver; Rajabi, Mojtaba; Ziegler, Moritz; Reiter, Karsten

    2016-04-01

    The World Stress Map (WSM) Project was initiated in 1986 under the auspices of the International Lithosphere Program in order to compile the global information on the contemporary crustal stress state. The data come from a wide range of stress indicators such as borehole data (e.g. hydraulic fracturing, borehole breakouts), earthquake focal mechanism solutions, engineering methods (e.g. overcoring), and geological data (e.g. inversion of fault slip measurements). To guarantee the comparability of the different data sources each data record is assessed with the WSM quality ranking scheme. For the 30th anniversary we compiled a new WSM database with 42,410 data records which is an increase by >20,000 data records compared to the WSM 2008 database. In particular we added new data from more than 3,500 deep boreholes and put special emphasis on regions which previously had sparse or no published stress data such as China, Australia, Brazil, Southern Africa, Middle East and Iceland. Furthermore, we fully integrated the Chinese stress database and the Australian stress database. The resulting data increase reveals several areas with regional and local variability of the stress pattern. In particular we re-visited the question whether the plate boundary forces are the key control of the plate-wide stress pattern as indicated by the first release of the WSM in 1989 [Zoback et al, 1989]. As the WSM has now more than 10 times data records and thus a better spatial coverage we first filter the long-wave length stress pattern on a regular grid. We determine at these grid points the difference between absolute plate motion azimuth using the global plate model HS3-NUVEL1A [Gripp and Gordon, 2002] and the mean orientation of the maximum horizontal stress. The preliminary results show that the earlier findings are still valid in principal. However, all plates show in some parts significant deviations from this general trend; some plates such as the Australian Plate show hardly any

  17. Long-Period Ground Motion Prediction Equations for Relative, Pseudo-Relative and Absolute Velocity Response Spectra in Japan

    NASA Astrophysics Data System (ADS)

    Dhakal, Y. P.; Kunugi, T.; Suzuki, W.; Aoi, S.

    2014-12-01

    Many of the empirical ground motion prediction equations (GMPE) also known as attenuation relations have been developed for absolute acceleration or pseudo relative velocity response spectra. For a small damping, pseudo and absolute acceleration response spectra are nearly identical and hence interchangeable. It is generally known that the relative and pseudo relative velocity response spectra differ considerably at very short or very long periods, and the two are often considered similar at intermediate periods. However, observations show that the period range at which the two spectra become comparable is different from site to site. Also, the relationship of the above two types of velocity response spectra with absolute velocity response spectra are not discussed well in literature. The absolute velocity response spectra are the peak values of time histories obtained by adding the ground velocities to relative velocity response time histories at individual natural periods. There exists many tall buildings on huge and deep sedimentary basins such as the Kanto basin, and the number of such buildings is growing. Recently, Japan Meteorological Agency (JMA) has proposed four classes of long-period ground motion intensity (http://www.data.jma.go.jp/svd/eew/data/ltpgm/) based on absolute velocity response spectra, which correlate to the difficulty of movement of people in tall buildings. As the researchers are using various types of response spectra for long-period ground motions, it is important to understand the relationships between them to take appropriate measures for disaster prevention applications. In this paper, we, therefore, obtain and discuss the empirical attenuation relationships using the same functional forms for the three types of velocity response spectra computed from observed strong motion records from moderate to large earthquakes in relation to JMA magnitude, hypocentral distance, sediment depths, and AVS30 as predictor variables at periods between

  18. Observations of 6.7 GHz methanol masers with East-Asian VLBI Network. II. Internal proper motion measurement in G006.79-00.25

    NASA Astrophysics Data System (ADS)

    Sugiyama, Koichiro; Fujisawa, Kenta; Hachisuka, Kazuya; Yonekura, Yoshinori; Motogi, Kazuhito; Sawada-Satoh, Satoko; Matsumoto, Naoko; Hirano, Daiki; Hayashi, Kyonosuke; Kobayashi, Hideyuki; Kawaguchi, Noriyuki; Shibata, Katsunori M.; Honma, Mareki; Hirota, Tomoya; Murata, Yasuhiro; Doi, Akihiro; Ogawa, Hideo; Kimura, Kimihiro; Niinuma, Kotaro; Chen, Xi; Xia, Bo; Li, Bin; Sorai, Kazuo; Momose, Munetake; Saito, Yu; Takaba, Hiroshi; Omodaka, Toshihiro; Kim, Kee-Tae; Shen, Zhiqiang

    2015-10-01

    We detected internal proper motions of the methanol maser features at 6.7 GHz in a high-mass star-forming region G006.79-00.25 with the East-Asian VLBI Network. The spatial distribution of the maser features shows an elliptical morphology. The internal proper motions of 17 methanol maser features relative to the barycenter of the features were measured. The amplitude of the internal motions ranged from 1.30 to 10.25 km s-1. Most of the internal proper motions of the maser features seem to point counterclockwise along the elliptical morphology of the maser features. We applied the disk model, which includes both rotating and expanding components, to the observed positions, l.o.s. velocities, and proper motions. The derived rotation, expansion, and systemic velocities are +3^{+2}_{-2}, +6^{+2}_{-2}, and +21^{+2}_{-2}km s-1, respectively, at the radius of 1260 au on the disk with a position angle of the semi-major axis of - 140° and an inclination of 60°. The derived rotating motion suggests that the methanol maser emissions showing the elliptical spatial morphology possibly trace the rotating disk. The derived expanding motion might be caused by the magnetic-centrifugal wind on the disk, which was estimated on the basis of the typical magnetic field strength at emitting zones of a methanol maser.

  19. Beyond the Blur: Construction and Characterization of the First Autonomous AO System, and, An AO Survey of Magnetar Proper Motions

    NASA Astrophysics Data System (ADS)

    Tendulkar, Shriharsh Prakash

    Adaptive optics (AO) corrects distortions created by atmospheric turbulence and delivers diffraction-limited images on ground-based telescopes. The vastly improved spatial resolution and sensitivity has been utilized for studying everything from the magnetic fields of sunspots upto the internal dynamics of high-redshift galaxies. This thesis about AO science from small and large telescopes is divided into two parts: Robo-AO and magnetar kinematics. In the first part, I discuss the construction and performance of the world's first fully autonomous visible light AO system, Robo-AO, at the Palomar 60-inch telescope. Robo-AO operates extremely efficiently with an overhead < 50s, typically observing about 22 targets every hour. We have performed large AO programs observing a total of over 7,500 targets since May 2012. In the visible band, the images have a Strehl ratio of about 10% and achieve a contrast of upto 6 magnitudes at a separation of 1‧‧. The full-width at half maximum achieved is 110-130 milli-arcsecond. I describe how Robo-AO is used to constrain the evolutionary models of low-mass pre-main-sequence stars by measuring resolved spectral energy distributions of stellar multiples in the visible band, more than doubling the current sample. I conclude this part with a discussion of possible future improvements to the Robo-AO system. In the second part, I describe a study of magnetar kinematics using high-resolution near-infrared (NIR) AO imaging from the 10-meter Keck II telescope. Measuring the proper motions of five magnetars with a precision of upto 0.7 milli-arcsecond/yr -1, we have more than tripled the previously known sample of magnetar proper motions and proved that magnetar kinematics are equivalent to those of radio pulsars. We conclusively showed that SGR 1900+14 and SGR 1806-20 were ejected from the stellar clusters with which they were traditionally associated. The inferred kinematic ages of these two magnetars are 6 +/- 1.8 kyr and 650 +/-3 00

  20. Characterization of the Praesepe star cluster by photometry and proper motions with 2MASS, PPMXL, and Pan-STARRS

    SciTech Connect

    Wang, P. F.; Chen, W. P.; Lin, C. C.; Huang, C. K.; Panwar, N.; Lee, C. H.; Pandey, A. K.; Tsai, M. F.; Tang, C.-H.; Goldman, B.; Burgett, W. S.; Chambers, K. C.; Flewelling, H.; Heasley, J. N.; Hodapp, K. W.; Huber, M. E.; Jedicke, R.; Kaiser, N.; Draper, P. W.; Grav, T.; and others

    2014-03-20

    Membership identification is the first step in determining the properties of a star cluster. Low-mass members in particular could be used to trace the dynamical history, such as mass segregation, stellar evaporation, or tidal stripping, of a star cluster in its Galactic environment. We identified member candidates of the intermediate-age Praesepe cluster (M44) with stellar masses ∼0.11-2.4 M {sub ☉}, using Panoramic Survey Telescope And Rapid Response System and Two Micron All Sky Survey photometry, and PPMXL proper motions. Within a sky area of 3° radius, 1040 candidates are identified, of which 96 are new inclusions. Using the same set of selection criteria on field stars, an estimated false positive rate of 16% was determined, suggesting that 872 of the candidates are true members. This most complete and reliable membership list allows us to favor the BT-Settl model over other stellar models. The cluster shows a distinct binary track above the main sequence, with a binary frequency of 20%-40%, and a high occurrence rate of similar mass pairs. The mass function is consistent with that of the disk population but shows a deficit of members below 0.3 solar masses. A clear mass segregation is evidenced, with the lowest-mass members in our sample being evaporated from this disintegrating cluster.

  1. Confirmation of the OGLE-2005-BLG-169 Planet Signature and Its Characteristics with Lens-Source Proper Motion Detection

    NASA Astrophysics Data System (ADS)

    Batista, V.; Beaulieu, J.-P.; Bennett, D. P.; Gould, A.; Marquette, J.-B.; Fukui, A.; Bhattacharya, A.

    2015-08-01

    We present Keck NIRC2 high angular resolution adaptive optics observations of the microlensing event OGLE-2005-BLG-169Lb, taken 8.21 years after the discovery of this planetary system. For the first time for a microlensing planetary event, the source and the lens are completely resolved, providing a precise measurement of their heliocentric relative proper motion, {μ }{rel,{helio}}=7.44+/- 0.17 mas yr-1. This confirms and refines the initial model presented in the discovery paper and rules out a range of solutions that were allowed by the microlensing light curve. This is also the first time that parameters derived from a microlensing planetary signal are confirmed, both with the Keck measurements, presented in this paper, and independent measurements obtained with the Hubble Space Telescope in I,V and B bands, presented in a companion paper. Hence, this new measurement of {μ }{rel,{helio}}, as well as the measured brightness of the lens in H band, enabled the mass and distance of the system to be updated: a Uranus-mass planet ({m}{{p}}=13.2+/- 1.3{M}\\oplus ) orbiting a K5-type main sequence star ({M}*=0.65+/- 0.05{M}⊙ ) separated by {a}\\perp =3.4+/- 0.3 AU, at the distance {D}{{L}}=4.0+/- 0.4 kpc from us.

  2. X-Ray Analysis of the Proper Motion and Pulsar Wind Nebula for PSR J1741-2054

    NASA Technical Reports Server (NTRS)

    Auchettl, Katie; Slane, Patrick; Romani, Roger W.; Posselt, Bettina; Pavlov, George G.; Kargaltsev, Oleg; Ng, C-Y.; Temim, Tea; Weisskopf, Martin C.; Bykov, Andrei; Swartz, Douglas

    2015-01-01

    We obtained six observations of PSR J1741-2054 using the Chandra ACIS-S detector totaling approx.300 ks. By registering this new epoch of observations to an archival observation taken 3.2 yr earlier using X-ray point sources in the field of view, we have measured the pulsar proper motion at micron = 109 +/- 10 mas yr(exp. -1) in a direction consistent with the symmetry axis of the observed H(alpha) nebula. We investigated the inferred past trajectory of the pulsar but find no compelling association with OB associations in which the progenitor may have originated. We confirm previous measurements of the pulsar spectrum as an absorbed power law with photon index gamma = 2.68 +/- 0.04, plus a blackbody with an emission radius of (4.5(+3.2/-2.5))d(0.38) km, for a DM-estimated distance of 0.38d(0.38) kpc and a temperature of 61.7 +/- 3.0 eV. Emission from the compact nebula is well described by an absorbed power law model with a photon index of gamma = 1.67 +/- 0.06, while the diffuse emission seen as a trail extending northeast of the pulsar shows no evidence of synchrotron cooling. We also applied image deconvolution techniques to search for small-scale structures in the immediate vicinity of the pulsar, but found no conclusive evidence for such structures.

  3. LOW-MASS TERTIARY COMPANIONS TO SPECTROSCOPIC BINARIES. I. COMMON PROPER MOTION SURVEY FOR WIDE COMPANIONS USING 2MASS

    SciTech Connect

    Allen, Peter R.; Burgasser, Adam J.; Faherty, Jacqueline K.; Kirkpatrick, J. Davy

    2012-08-15

    We report the first results of a multi-epoch search for wide (separations greater than a few tens of AU), low-mass tertiary companions of a volume-limited sample of 118 known spectroscopic binaries within 30 pc of the Sun, using the Two Micron All Sky Survey Point Source Catalog and follow-up observations with the KPNO and CTIO 4 m telescopes. Note that this sample is not volume complete but volume limited, and, thus, there is incompleteness in our reported companion rates. We are sensitive to common proper motion companions with separations from roughly 200 AU to 10,000 AU ({approx}10'' {yields} {approx} 10'). From 77 sources followed-up to date, we recover 11 previously known tertiaries, 3 previously known candidate tertiaries, of which 2 are spectroscopically confirmed and 1 rejected, and 3 new candidates, of which 2 are confirmed and 1 rejected. This yields an estimated wide tertiary fraction of 19.5{sup +5.2}{sub -3.7}%. This observed fraction is consistent with predictions set out in star formation simulations where the fraction of wide, low-mass companions to spectroscopic binaries is >10%.

  4. The expansion proper motions of the extraordinary giant lobes of the planetary nebula KjPn 8 revisited

    NASA Astrophysics Data System (ADS)

    Boumis, P.; Meaburn, J.

    2013-04-01

    The primary aim is to establish a firm value for the distance to the extraordinary planetary nebula KjPn 8. Secondary aims are to measure the ages of the three giant lobes of this object as well as estimate the energy in the eruption, that caused the most energetic outflow, for comparison with that of an intermediate-luminosity optical transient (ILOT). For these purposes a mosaic of images in the Hα + [N II] optical emission lines has been obtained with the new Aristarchos telescope in 2011 for comparison with the images of the KjPn 8 giant lobes present on the Palomar Observatory Sky Survey (POSSI-R) 1954 and POSSII-R 1991 plates. Expansion proper motions of features over this 57 yr baseline in the outflows are present. Using these, a firm distance to KjPn 8 of 1.8 ± 0.3 kpc has been derived for now the angle of the latest outflow to the sky has been established from Hubble Space Telescope imagery of the nebular core. Previously, the uncertain predictions of a bow-shock model were used for this purpose. The dynamical ages of the three separate outflows that form the giant lobes of KjPn 8 are also directly measured as 3200, 7200 and ≥5 × 104 yr, respectively, which confirms their sequential ejection. Moreover, the kinetic energy of the youngest and most energetic of these is measured as ≈1047 erg which is compatible with an ILOT origin.

  5. UCAC3 PROPER MOTION SURVEY. II. DISCOVERY OF NEW PROPER MOTION STARS IN UCAC3 WITH 0.''40 yr{sup -1} > {mu} {>=} 0.''18 yr{sup -1} BETWEEN DECLINATIONS -47 Degree-Sign and 00 Degree-Sign

    SciTech Connect

    Finch, Charlie T.; Zacharias, Norbert; Boyd, Mark R.; Henry, Todd J.; Hambly, Nigel C.

    2012-02-01

    We present 474 new proper motion stellar systems in the southern sky having no previously known components, with 0.''40 yr{sup -1} >{mu} {>=} 0.''18 yr{sup -1} between declinations -47 Degree-Sign and 0 Degree-Sign . In this second paper utilizing the U.S. Naval Observatory third CCD Astrograph Catalog (UCAC3) we complete our sweep of the southern sky for objects in the proper motion range targeted by this survey with R magnitudes ranging from 9.80 to 19.61. The new systems contribute a {approx}16% increase in the number of new stellar systems for the same region of sky reported in previous SuperCOSMOS Research Consortium On Nearby Stars (RECONS) surveys. Among the newly discovered stellar systems are 16 multiples, plus an additional ten components that are new common proper motion companions to previously known objects. A comparison of UCAC3 proper motions to those from Hipparcos, Tycho-2, Southern Proper Motion, and SuperCOSMOS indicates that all proper motions are consistent to {approx}10 mas yr{sup -1}, with the exception of SuperCOSMOS. Distance estimates are derived for all stellar systems having SuperCOSMOS Sky Survey B{sub J} , R{sub 59F}, and I{sub IVN} plate magnitudes and Two Micron All Sky Survey (2MASS) infrared photometry. We find five new red dwarf systems estimated to be within 25 pc. These discoveries support results from previous proper motion surveys suggesting that more nearby stellar systems are to be found, particularly in the fainter, slower moving samples. In this second paper utilizing the UCAC3 we complete our sweep of the southern sky for objects in the proper motion range targeted by this survey with R magnitudes ranging from 9.80 to 19.61.

  6. HUBBLE SPACE TELESCOPE PROPER MOTION (HSTPROMO) CATALOGS OF GALACTIC GLOBULAR CLUSTERS. I. SAMPLE SELECTION, DATA REDUCTION, AND NGC 7078 RESULTS

    SciTech Connect

    Bellini, A.; Anderson, J.; Van der Marel, R. P.; Watkins, L. L.; King, I. R.; Bianchini, P.; Chanamé, J.; Chandar, R.; Cool, A. M.; Ferraro, F. R.; Massari, D.; Ford, H.

    2014-12-20

    We present the first study of high-precision internal proper motions (PMs) in a large sample of globular clusters, based on Hubble Space Telescope (HST) data obtained over the past decade with the ACS/WFC, ACS/HRC, and WFC3/UVIS instruments. We determine PMs for over 1.3 million stars in the central regions of 22 clusters, with a median number of ∼60,000 stars per cluster. These PMs have the potential to significantly advance our understanding of the internal kinematics of globular clusters by extending past line-of-sight (LOS) velocity measurements to two- or three-dimensional velocities, lower stellar masses, and larger sample sizes. We describe the reduction pipeline that we developed to derive homogeneous PMs from the very heterogeneous archival data. We demonstrate the quality of the measurements through extensive Monte Carlo simulations. We also discuss the PM errors introduced by various systematic effects and the techniques that we have developed to correct or remove them to the extent possible. We provide in electronic form the catalog for NGC 7078 (M 15), which consists of 77,837 stars in the central 2.'4. We validate the catalog by comparison with existing PM measurements and LOS velocities and use it to study the dependence of the velocity dispersion on radius, stellar magnitude (or mass) along the main sequence, and direction in the plane of the sky (radial or tangential). Subsequent papers in this series will explore a range of applications in globular-cluster science and will also present the PM catalogs for the other sample clusters.

  7. Hubble Space Telescope Proper Motion (HSTPROMO) Catalogs of Galactic Globular Clusters. III. Dynamical Distances and Mass-to-Light Ratios

    NASA Astrophysics Data System (ADS)

    Watkins, Laura L.; van der Marel, Roeland P.; Bellini, Andrea; Anderson, Jay

    2015-10-01

    We present dynamical distance estimates for 15 Galactic globular clusters (GCs) and use these to check the consistency of dynamical and photometric distance estimates. For most of the clusters, this is the first dynamical distance estimate ever determined. We extract proper-motion (PM) dispersion profiles using cleaned samples of bright stars from the Hubble Space Telescope PM catalogs recently presented in Bellini et al. and compile a set of line of sight (LOS) velocity-dispersion profiles from a variety of literature sources. Distances are then estimated by fitting spherical, non-rotating, isotropic, constant mass-to-light ratio (M/L) dynamical models to the PM and LOS dispersion profiles together. We compare our dynamical distance estimates with literature photometric estimates from the Harris GC catalog and find that the mean fractional difference between the two types is consistent with zero at just -1.9 ± 1.7%. This indicates that there are no significant biases in either estimation method and provides an important validation of the stellar-evolution theory that underlies photometric distance estimates. The analysis also estimates dynamical M/Ls for our clusters; on average, the dynamically inferred M/Ls agree with existing stellar-population-based M/Ls that assume a Chabrier initial mass function (IMF) to within -8.8 ± 6.4%, implying that such an IMF is consistent with our data. Our results are also consistent with a Kroupa IMF, but strongly rule out a Salpeter IMF. We detect no correlation between our M/L offsets from literature values and our distance offsets from literature values, strongly indicating that our methods are reliable and our results are robust. Based on proprietary and archival observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by AURA, Inc., under NASA contract NAS 5-26555.

  8. THE PROPER MOTION AND X-RAY ANALYSIS OF THE PULSAR WIND NEBULA, PSR J1741-2054 USING CHANDRA.

    NASA Astrophysics Data System (ADS)

    Auchettl, Katie; Slane, Patrick O.; Romani, Roger W.; Kargaltsev, Oleg; Pavlov, George G.

    2014-08-01

    A pulsar dissipates its rotational energy by generating relativistic winds, which in turn produces a population of high energy electrons and positions that we observe as a synchrotron emitting nebula. If the pulsar has a high space velocity, the corresponding nebula will have a bow-shock morphology due to the pulsar wind being confined by ram pressure. Pulsar wind nebulae (PWNe) provide a good test bed to study the dynamics and interaction of relativistic outflows with their environment and the corresponding shocks that result from these interactions. They can also aid in understanding the evolution of the neutron star and the properties of the local medium with which they are interacting. Here we report on the X-ray analysis of PSR J1741-2054 carried out as a part of the Chandra XVP program (6 ACIS-S observations, totalling ~300 ks over 5 months). By registering this new epoch of observations using X-ray point sources in the field of view to an archival observation taken 3.2 years earlier, we are able to measure the proper motion of the pulsar with >3σ significance. We also investigate the spatial and spectral properties of the pulsar, its compact nebula and extended tail. We find that the compact nebula can be well described with an absorbed power-law with photon index of Γ=1.6+/-0.2, while the tail shows no evidence of variation in the spectral index with the distance from the pulsar. We have also investigated the X-ray spectrum of the neutron star. We find nonthermal emission accompanied by a significant thermal component and will provide constraints on the overall nature of the emission.

  9. A study of high proper-motion white dwarfs - I. Spectropolarimetry of a cool hydrogen-rich sample

    NASA Astrophysics Data System (ADS)

    Kawka, Adéla; Vennes, Stéphane

    2012-09-01

    We conducted a spectropolarimetic survey of 58 high proper-motion white dwarfs which achieved uncertainties of >rsim 2 kG in the Hα line and >rsim 5 kG in the upper Balmer line series. The survey aimed at detecting low magnetic fields (≲ 100 kG) and helped identify the new magnetic white dwarfs NLTT 2219, with a longitudinal field Bl = -97 kG, and NLTT 10480 (Bl = -212 kG). Furthermore, we report the possible identification of a very low-field white dwarf with Bl = -4.6 kG. The observations show that ≈5 per cent of white dwarfs harbour low fields (˜10 to ˜102 kG) and that increased survey sensitivity may help uncover several new magnetic white dwarfs with fields below ˜1 kG. A series of observations of the high-field white dwarf NLTT 12758 revealed changes in polarity occurring within an hour possibly associated with an inclined, fast rotating dipole. Also, the relative strength of the π and σ components in NLTT 12758 possibly revealed the effect of a field concentration ('spot'), or, most likely, the presence of a non-magnetic white dwarf companion. Similar observations of NLTT 13015 also showed possible polarity variations, but without a clear indication of the time-scale. The survey data also proved useful in constraining the chemical composition, age and kinematics of a sample of cool white dwarfs as well as in constraining the incidence of double degenerates. Based on observations made with ESO telescopes at the La Silla Paranal Observatory under programme IDs 80.D-0521, 82.D-0521, 83.D-0750 and 84.D-0862.

  10. Third-epoch Magellanic Cloud proper motions. II. The large Magellanic Cloud rotation field in three dimensions

    SciTech Connect

    Van der Marel, Roeland P.; Kallivayalil, Nitya

    2014-02-01

    We present the first detailed assessment of the large-scale rotation of any galaxy based on full three-dimensional velocity measurements. We do this for the LMC by combining our Hubble Space Telescope average proper motion (PM) measurements for stars in 22 fields, with existing line-of-sight (LOS) velocity measurements for 6790 individual stars. We interpret these data with a model of circular rotation in a flat disk. The PM and LOS data paint a consistent picture of the LMC rotation, and their combination yields several new insights. The PM data imply a stellar dynamical center that coincides with the H I dynamical center, and a rotation curve amplitude consistent with that inferred from LOS velocity studies. The implied disk viewing angles agree with the range of values found in the literature, but continue to indicate variations with stellar population and/or radius. Young (red supergiant) stars rotate faster than old (red and asymptotic giant branch) stars due to asymmetric drift. Outside the central region, the circular velocity is approximately flat at V {sub circ} = 91.7 ± 18.8 km s{sup –1}. This is consistent with the baryonic Tully-Fisher relation and implies an enclosed mass M(8.7 kpc) = (1.7 ± 0.7) × 10{sup 10} M {sub ☉}. The virial mass is larger, depending on the full extent of the LMC's dark halo. The tidal radius is 22.3 ± 5.2 kpc (24.°0 ± 5.°6). Combination of the PM and LOS data yields kinematic distance estimates for the LMC, but these are not yet competitive with other methods.

  11. Hubble Space Telescope Proper Motion (HSTPROMO) Catalogs of Galactic Globular Clusters. I. Sample Selection, Data Reduction, and NGC 7078 Results

    NASA Astrophysics Data System (ADS)

    Bellini, A.; Anderson, J.; van der Marel, R. P.; Watkins, L. L.; King, I. R.; Bianchini, P.; Chanamé, J.; Chandar, R.; Cool, A. M.; Ferraro, F. R.; Ford, H.; Massari, D.

    2014-12-01

    We present the first study of high-precision internal proper motions (PMs) in a large sample of globular clusters, based on Hubble Space Telescope (HST) data obtained over the past decade with the ACS/WFC, ACS/HRC, and WFC3/UVIS instruments. We determine PMs for over 1.3 million stars in the central regions of 22 clusters, with a median number of ~60,000 stars per cluster. These PMs have the potential to significantly advance our understanding of the internal kinematics of globular clusters by extending past line-of-sight (LOS) velocity measurements to two- or three-dimensional velocities, lower stellar masses, and larger sample sizes. We describe the reduction pipeline that we developed to derive homogeneous PMs from the very heterogeneous archival data. We demonstrate the quality of the measurements through extensive Monte Carlo simulations. We also discuss the PM errors introduced by various systematic effects and the techniques that we have developed to correct or remove them to the extent possible. We provide in electronic form the catalog for NGC 7078 (M 15), which consists of 77,837 stars in the central 2.'4. We validate the catalog by comparison with existing PM measurements and LOS velocities and use it to study the dependence of the velocity dispersion on radius, stellar magnitude (or mass) along the main sequence, and direction in the plane of the sky (radial or tangential). Subsequent papers in this series will explore a range of applications in globular-cluster science and will also present the PM catalogs for the other sample clusters. Based on proprietary and archival observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by AURA, Inc., under NASA contract NAS 5-26555.

  12. DISTANCE AND PROPER MOTION MEASUREMENT OF THE RED SUPERGIANT, PZ CAS, IN VERY LONG BASELINE INTERFEROMETRY H{sub 2}O MASER ASTROMETRY

    SciTech Connect

    Kusuno, K.; Asaki, Y.; Imai, H.; Oyama, T. E-mail: asaki@vsop.isas.jaxa.jp E-mail: t.oyama@nao.ac.jp

    2013-09-10

    We present the very long baseline interferometry H{sub 2}O maser monitoring observations of the red supergiant, PZ Cas, at 12 epochs from 2006 April to 2008 May. We fitted maser motions to a simple model composed of a common annual parallax and linear motions of the individual masers. The maser motions with the parallax subtracted were well modeled by a combination of a common stellar proper motion and a radial expansion motion of the circumstellar envelope. We obtained an annual parallax of 0.356 {+-} 0.026 mas and a stellar proper motion of {mu}{sub {alpha}}{sup *} cos {delta} = -3.7 {+-} 0.2 and {mu}{sup *}{sub {delta}}=-2.0{+-}0.3 mas yr{sup -1} eastward and northward, respectively. The annual parallax corresponds to a trigonometric parallax of 2.81{sup +0.22}{sub -0.19} kpc. By rescaling the luminosity of PZ Cas in any previous studies using our trigonometric parallax, we estimated the location of PZ Cas on a Hertzsprung-Russell diagram and found that it approaches a theoretically evolutionary track around an initial mass of {approx}25 M{sub Sun }. The sky position and the distance to PZ Cas are consistent with the OB association, Cas OB5, which is located in a molecular gas super shell. The proper motion of PZ Cas is close to that of the OB stars and other red supergiants in Cas OB5 measured by the Hipparcos satellite. We derived the peculiar motion of PZ Cas of U{sub s} = 22.8 {+-} 1.5, V{sub s} = 7.1 {+-} 4.4, and W{sub s} = -5.7 {+-} 4.4 km s{sup -1}. This peculiar motion has rather a large U{sub s} component, unlike those of near high-mass star-forming regions with negatively large V{sub s} motions. The uniform proper motions of the Cas OB5 member stars suggest random motions of giant molecular clouds moving into local potential minima in a time-dependent spiral arm, rather than a velocity field caused by the spiral arm density wave.

  13. New Method to Measure Proper Motions of Microlensed Sources: Application to Candidate Free-floating-planet Event MOA-2011-BLG-262

    NASA Astrophysics Data System (ADS)

    Skowron, Jan; Udalski, Andrzej; Szymański, Michał K.; Kubiak, Marcin; Pietrzyński, Grzegorz; Soszyński, Igor; Poleski, Radosław; Ulaczyk, Krzysztof; Pietrukowicz, Paweł; Kozłowski, Szymon; Wyrzykowski, Łukasz; Gould, Andrew

    2014-04-01

    We develop a new method to measure source proper motions in microlensing events, which can partially overcome problems due to blending. It takes advantage of the fact that the source position is known precisely from the microlensing event itself. We apply this method to the event MOA-2011-BLG-262, which has a short timescale t E = 3.8 day, a companion mass ratio q = 4.7 × 10-3, and a very high or high lens-source relative proper motion μrel = 20 mas yr-1 or 12 mas yr-1 (for two possible models). These three characteristics imply that the lens could be a brown dwarf or a massive planet with a roughly Earth-mass "moon." The probability of such an interpretation would be greatly increased if it could be shown that the high lens-source relative proper motion was primarily due to the lens rather than the source. Based on the long-term monitoring data of the Galactic bulge from the Optical Gravitational Lensing Experiment, we measure the source proper motion that is small, {\\boldsymbol {\\mu }}_s = (-2.3, -0.9)+/- (2.8,2.6)\\,mas\\:yr^{-1} in a (north, east) Galactic coordinate frame. These values are then important input into a Bayesian analysis of the event presented in a companion paper by Bennett et al. Based on observations obtained with the 1.3 m Warsaw telescope at the Las Campanas Observatory of the Carnegie Institution for Science.

  14. Giclas 112-29 (=NLTT 18149), A Very Wide Companion To GJ 282 AB With Common Proper Motion, Common Parallax, Common Radial Velocity and Common Age

    NASA Astrophysics Data System (ADS)

    Poveda, A.; Hernández-Alcántara, A.; Costero, R.; Echevarría, J.

    2008-12-01

    We have made a search for Common Proper Motion Companions to the wide binaries in the solar vicinity. We found that the binary GJ 282AB has a very wide CPM companion (NLTT 18149) at a separation s = 1.09°. Hipparcos trigonometric parallaxes, radial velocities and ages are very similar, suggesting a physical system.

  15. New method to measure proper motions of microlensed sources: Application to candidate free-floating-planet event MOA-2011-BLG-262

    SciTech Connect

    Skowron, Jan; Udalski, Andrzej; Szymański, Michał K. E-mail: udalski@astrouw.edu.pl; and others

    2014-04-20

    We develop a new method to measure source proper motions in microlensing events, which can partially overcome problems due to blending. It takes advantage of the fact that the source position is known precisely from the microlensing event itself. We apply this method to the event MOA-2011-BLG-262, which has a short timescale t {sub E} = 3.8 day, a companion mass ratio q = 4.7 × 10{sup –3}, and a very high or high lens-source relative proper motion μ{sub rel} = 20 mas yr{sup –1} or 12 mas yr{sup –1} (for two possible models). These three characteristics imply that the lens could be a brown dwarf or a massive planet with a roughly Earth-mass 'moon'. The probability of such an interpretation would be greatly increased if it could be shown that the high lens-source relative proper motion was primarily due to the lens rather than the source. Based on the long-term monitoring data of the Galactic bulge from the Optical Gravitational Lensing Experiment, we measure the source proper motion that is small, μ{sub s}=(−2.3,−0.9)±(2.8,2.6) mas yr{sup −1} in a (north, east) Galactic coordinate frame. These values are then important input into a Bayesian analysis of the event presented in a companion paper by Bennett et al.

  16. Outer rotation curve of the Galaxy with VERA. II. Annual parallax and proper motion of the star-forming region IRAS 21379+5106

    NASA Astrophysics Data System (ADS)

    Nakanishi, Hiroyuki; Sakai, Nobuyuki; Kurayama, Tomoharu; Matsuo, Mitsuhiro; Imai, Hiroshi; Burns, Ross A.; Ozawa, Takeaki; Honma, Mareki; Shibata, Katsunori M.; Kawaguchi, Noriyuki

    2015-08-01

    We conducted astrometric very long baseline interferometry (VLBI) observations of water-vapor maser emission in the massive star-forming region IRAS 21379+5106 in order to measure the annual parallax and proper motion, using VLBI Exploration of Radio Astrometry (VERA). The annual parallax measured 0.262 ± 0.031 mas, corresponding to a distance of 3.82^{+0.51}_{-0.41}kpc. The proper motion was (μαcos δ, μδ) = (-2.74 ± 0.08, -2.87 ± 0.18) mas yr-1. By using this result, the Galactic rotational velocity was estimated to be Vθ = 218 ± 19 km s-1 at the galactocentric distance R = 9.22 ± 0.43 kpc, when we adopted the Galactic constants R0 = 8.05 ± 0.45 kpc and V0 = 238 ± 14 km s-1. With the newly determined distance, the bolometric luminosity of the central young stellar object was reestimated to be (2.15 ± 0.54) × 103 L⊙, which corresponds to the spectral type of B2-B3. The maser features were found to be distributed along a straight line extending from the southwest to the northeast. In addition, a vector map of the internal motions, constructed from the residual proper motions, implies that the maser features trace a bipolar flow, and that it cannot be explained by simple ballistic motions.

  17. Large proper motion of the Thorne-Żytkow object candidate HV 2112 reveals its likely nature as foreground Galactic S-star

    NASA Astrophysics Data System (ADS)

    Maccarone, Thomas J.; de Mink, Selma E.

    2016-05-01

    Using the Southern Proper Motion (SPM) catalogue, we show that the candidate Thorne-Żytkow object HV 2112 has a proper motion implying a space velocity of about 3000 {km} {s}^{-1}if the object is located at the distance of the Small Magellanic Cloud (SMC). The proper motion is statistically different from that of the SMC at approximately 4σ in SPM, although the result can drop to about 3σ significance by including the UCAC4 data and considering systematic uncertainties in addition to the statistical ones. Assuming the measurement is robust, this proper motion is sufficient to exclude its proposed membership of the SMC and to argue instead that it is likely to be a foreground star in the Milky Way halo. The smaller distance and therefore lower brightness argue against its proposed nature as a Thorne-Żytkow object (the hypothesized star-like object formed when a normal star and a neutron star merge) or a Asymptotic Giant Branch (AGB) star. Instead we propose a binary scenario where this star is the companion of a former massive AGB star, which polluted the object with via its stellar wind, i.e. a special case of an extrinsic S star. Our new scenario solves two additional problems with the two existing scenarios for its nature as Thorne-Żytkow object or present-day super AGB star. The puzzling high ratio of the strength of calcium to iron absorption lines is unexpected for SMC supergiants, but is fully consistent with the expectations for halo abundances. Secondly, its strong variability can now be explained naturally as a manifestation of the Mira phenomenon. We discuss further observational tests that could distinguish between the foreground and SMC scenarios in advance of the improved proper motion measurements likely to come from Gaia.

  18. The Brown Dwarf Kinematics Project. II. Details on Nine Wide Common Proper Motion Very Low Mass Companions to Nearby Stars

    NASA Astrophysics Data System (ADS)

    Faherty, Jacqueline K.; Burgasser, Adam J.; West, Andrew A.; Bochanski, John J.; Cruz, Kelle L.; Shara, Michael M.; Walter, Frederick M.

    2010-01-01

    We report on nine wide common proper motion systems containing late-type M, L, or T companions. We confirm six previously reported companions, and identify three new systems. The ages of these systems are determined using diagnostics for both stellar primaries and low-mass secondaries and masses for the secondaries are inferred using evolutionary models. Of our three new discoveries, the M3+T6.5 pair G 204-39 and SDSS J1758+4633 has an age constrained to 0.5-1.5 Gyr making the secondary a potentially useful brown dwarf benchmark. The G5+L4 pair G 200-28 and SDSS J1416+5006 has a projected separation of ~25,000 AU making it one of the widest and lowest binding energy systems known to date. The system containing NLTT 2274 and SDSS J0041+1341 is an older M4+L0 (>4.5 Gyr) pair which shows Hα activity in the secondary but not the primary making it a useful tracer of age/mass/activity trends. Two of the nine systems have discrepant component ages that emerge from stellar or ultracool diagnostics indicating possible shortcomings in our understanding of the age diagnostics of stars and brown dwarfs. We find a resolved binary frequency for widely separated (>100 AU) low-mass companions (i.e., at least a triple system) which is at least twice the frequency found for the field ultracool dwarf population. The ratio of triples to binaries and quadruples to binaries is also high for this sample: 3:5 and 1:4, respectively, compared to 8 pc sample values of 1:4 and 1:26. The additional components in these wide companion systems indicates a formation mechanism that requires a third or fourth component to maintain gravitational stability or facilitate the exchange of angular momentum. The binding energies for the nine multiples discussed in this text are among the lowest known for wide low-mass systems, suggesting that weakly bound, low-to-intermediate mass (0.2 M sun < M tot< 1.0 M sun) multiples can form and survive to exist in the field (1-8 Gyr). This paper includes data

  19. THE BROWN DWARF KINEMATICS PROJECT. II. DETAILS ON NINE WIDE COMMON PROPER MOTION VERY LOW MASS COMPANIONS TO NEARBY STARS ,

    SciTech Connect

    Faherty, Jacqueline K.; Shara, Michael M.; Burgasser, Adam J.; West, Andrew A.; Bochanski, John J.; Cruz, Kelle L.; Walter, Frederick M.

    2010-01-15

    We report on nine wide common proper motion systems containing late-type M, L, or T companions. We confirm six previously reported companions, and identify three new systems. The ages of these systems are determined using diagnostics for both stellar primaries and low-mass secondaries and masses for the secondaries are inferred using evolutionary models. Of our three new discoveries, the M3+T6.5 pair G 204-39 and SDSS J1758+4633 has an age constrained to 0.5-1.5 Gyr making the secondary a potentially useful brown dwarf benchmark. The G5+L4 pair G 200-28 and SDSS J1416+5006 has a projected separation of {approx}25,000 AU making it one of the widest and lowest binding energy systems known to date. The system containing NLTT 2274 and SDSS J0041+1341 is an older M4+L0 (>4.5 Gyr) pair which shows H{alpha} activity in the secondary but not the primary making it a useful tracer of age/mass/activity trends. Two of the nine systems have discrepant component ages that emerge from stellar or ultracool diagnostics indicating possible shortcomings in our understanding of the age diagnostics of stars and brown dwarfs. We find a resolved binary frequency for widely separated (>100 AU) low-mass companions (i.e., at least a triple system) which is at least twice the frequency found for the field ultracool dwarf population. The ratio of triples to binaries and quadruples to binaries is also high for this sample: 3:5 and 1:4, respectively, compared to 8 pc sample values of 1:4 and 1:26. The additional components in these wide companion systems indicates a formation mechanism that requires a third or fourth component to maintain gravitational stability or facilitate the exchange of angular momentum. The binding energies for the nine multiples discussed in this text are among the lowest known for wide low-mass systems, suggesting that weakly bound, low-to-intermediate mass (0.2 M {sub sun} < M {sub tot}< 1.0 M {sub sun}) multiples can form and survive to exist in the field (1-8 Gyr)

  20. Improved Hubble Space Telescope proper motions for Tycho-G and other stars in the remnant of Tycho's Supernova 1572

    NASA Astrophysics Data System (ADS)

    Bedin, L. R.; Ruiz-Lapuente, P.; González Hernández, J. I.; Canal, R.; Filippenko, A. V.; Mendez, J.

    2014-03-01

    With archival and new Hubble Space Telescope observations, we have refined the space-velocity measurements of the stars in the central region of the remnant of Tycho's supernova (SN) 1572, one of the historical Galactic Type Ia supernova remnants (SNRs). We derived a proper motion for Tycho-G of (μαcos δ; μδ)J2000.0 = (-2.63; -3.98) ± (0.06; 0.04) [formal errors] ± (0.18; 0.10) [expected errors] mas yr-1. If the star were at the distance of the SNR (taken here to be 2.83 kpc), its velocity would be vb = -51 ± 1.5 km s-1. We also reconstruct the binary orbit that Tycho-G should have followed if it were the surviving companion of SN 1572. We redetermine the Ni abundance of this star and compare it with new abundance data from stars of the Galactic disc, finding that [Ni/Fe] is about 1.7σ above the Galactic trend. From the high velocity of Tycho-G perpendicular to the Galactic plane ( - 90 ± 3 km s-1 ≤ vb ≤ -45 ± 1 km s-1, for the allowed range of distances to the star), its metallicity and its Ni excess, we find the probability of it being a chance interloper to be P ≲ 0.000 37 at most. The projected rotational velocity of the star should be below current observational limits. The projected position of Tycho-G is, within the uncertainties, consistent with the centroid of the X-ray emission of Tycho's SNR; moreover, its brightness is generally consistent with the post-explosion evolution of the luminosity of an SN companion. Among the other 23 stars having V < 22 mag and located within 42 arcsec from the X-ray centroid, only 4 are at distances compatible with that of the SNR, and none of them shows any peculiarity. Therefore, if even Tycho-G is not the surviving companion of SN 1572, the absence of other viable candidates does favour the merging of two white dwarfs as the producer of the SN.

  1. Comparing the role of absolute sea-level rise and vertical tectonic motions in coastal flooding, Torres Islands (Vanuatu)

    NASA Astrophysics Data System (ADS)

    Ballu, Valérie; Bouin, Marie-Noëlle; Siméoni, Patricia; Crawford, Wayne C.; Calmant, Stephane; Boré, Jean-Michel; Kanas, Tony; Pelletier, Bernard

    2011-08-01

    Since the late 1990s, rising sea levels around the Torres Islands (north Vanuatu, southwest Pacific) have caused strong local and international concern. In 2002-2004, a village was displaced due to increasing sea incursions, and in 2005 a United Nations Environment Programme press release referred to the displaced village as perhaps the world's first climate change "refugees." We show here that vertical motions of the Torres Islands themselves dominate the apparent sea-level rise observed on the islands. From 1997 to 2009, the absolute sea level rose by 150 + /-20 mm. But GPS data reveal that the islands subsided by 117 + /-30 mm over the same time period, almost doubling the apparent gradual sea-level rise. Moreover, large earthquakes that occurred just before and after this period caused several hundreds of mm of sudden vertical motion, generating larger apparent sea-level changes than those observed during the entire intervening period. Our results show that vertical ground motions must be accounted for when evaluating sea-level change hazards in active tectonic regions. These data are needed to help communities and governments understand environmental changes and make the best decisions for their future.

  2. Comparing the role of absolute sea-level rise and vertical tectonic motions in coastal flooding, Torres Islands (Vanuatu)

    PubMed Central

    Ballu, Valérie; Bouin, Marie-Noëlle; Siméoni, Patricia; Crawford, Wayne C.; Calmant, Stephane; Boré, Jean-Michel; Kanas, Tony; Pelletier, Bernard

    2011-01-01

    Since the late 1990s, rising sea levels around the Torres Islands (north Vanuatu, southwest Pacific) have caused strong local and international concern. In 2002–2004, a village was displaced due to increasing sea incursions, and in 2005 a United Nations Environment Programme press release referred to the displaced village as perhaps the world’s first climate change “refugees.” We show here that vertical motions of the Torres Islands themselves dominate the apparent sea-level rise observed on the islands. From 1997 to 2009, the absolute sea level rose by 150 + /-20 mm. But GPS data reveal that the islands subsided by 117 + /-30 mm over the same time period, almost doubling the apparent gradual sea-level rise. Moreover, large earthquakes that occurred just before and after this period caused several hundreds of mm of sudden vertical motion, generating larger apparent sea-level changes than those observed during the entire intervening period. Our results show that vertical ground motions must be accounted for when evaluating sea-level change hazards in active tectonic regions. These data are needed to help communities and governments understand environmental changes and make the best decisions for their future. PMID:21795605

  3. Relative and Absolute Plate Motions, Mantle Plumes and Volcanism in the Arctic region

    NASA Astrophysics Data System (ADS)

    Gaina, C.; Torsvik, T. H.

    2012-04-01

    Seafloor spreading in the North Atlantic ocean from Mesozoic until present day involved relative motion between three major tectonic plates: North America, Greenland and Eurasia and a number of microplates. Relative motions between these tectonic plates and movement of northern Pacific terranes since the Jurassic led to the development of the Arctic region as we know it today. Studying the connection between the two realms involve good knowledge of the development of the North Atlantic and Arctic margins and oceanic basins and ideally, model uncertainties. Here we review the kinematics of North Atlantic and asses the implications of different models for locating the plate boundaries in the Arctic. One set of models implies extension before opening of the Eurasia basin and we postulate that this was accommodated in the proximity of Alpha- Mendeleev Ridge. The origin of (mainly) Cretaceous large igneous activity in the central Arctic (the Alpha Mendeleev Ridge) and in the proximity of rifted margins, the so-called HALIP, is still debated. New models of global plate circuits and the connection with deep mantle are used to re-evaluate a possible link between the Arctic volcanism and mantle plumes.

  4. OBJECTS APPEAR SMALLER AS THEY RECEDE: HOW PROPER MOTIONS CAN DIRECTLY REVEAL THE COSMIC EXPANSION, PROVIDE GEOMETRIC DISTANCES, AND MEASURE THE HUBBLE CONSTANT

    SciTech Connect

    Darling, Jeremy

    2013-11-10

    Objects and structures gravitationally decoupled from the Hubble expansion will appear to shrink in angular size as the universe expands. Observations of extragalactic proper motions can thus directly reveal the cosmic expansion. Relatively static structures such as galaxies or galaxy clusters can potentially be used to measure the Hubble constant, and test masses in large scale structures can measure the overdensity. Since recession velocities and angular separations can be precisely measured, apparent proper motions can also provide geometric distance measurements to static structures. The apparent fractional angular compression of static objects is 15 μas yr{sup –1} in the local universe; this motion is modulated by the overdensity in dynamic expansion-decoupled structures. We use the Titov et al. quasar proper motion catalog to examine the pairwise proper motion of a sparse network of test masses. Small-separation pairs (<200 Mpc comoving) are too few to measure the expected effect, yielding an inconclusive 8.3 ± 14.9 μas yr{sup –1}. Large-separation pairs (200-1500 Mpc) show no net convergence or divergence for z < 1, –2.7 ± 3.7 μas yr{sup –1}, consistent with pure Hubble expansion and significantly inconsistent with static structures, as expected. For all pairs a 'null test' gives –0.36 ± 0.62 μas yr{sup –1}, consistent with Hubble expansion and excludes a static locus at ∼5-10σ significance for z ≅ 0.5-2.0. The observed large-separation pairs provide a reference frame for small-separation pairs that will significantly deviate from the Hubble flow. The current limitation is the number of small-separation objects with precise astrometry, but Gaia will address this and will likely detect the cosmic recession.

  5. NEARBY YOUNG STARS SELECTED BY PROPER MOTION. I. FOUR NEW MEMBERS OF THE {beta} PICTORIS MOVING GROUP FROM THE TYCHO-2 CATALOG

    SciTech Connect

    Lepine, Sebastien; Simon, Michal E-mail: michal.simon@sunysb.edu

    2009-03-15

    We describe a procedure to identify stars from nearby moving groups and associations out of catalogs of stars with large proper motions. We show that from the mean motion vector of a known or suspected moving group, one can identify additional members of the group based on proper motion data and photometry in the optical and infrared, with minimal contamination from background field stars. We demonstrate this technique by conducting a search for low-mass members of the {beta} Pictoris moving group in the Tycho-2 catalog. All known members of the moving group are easily recovered, and a list of 51 possible candidates is generated. Moving group membership is evaluated for 33 candidates based on X-ray flux from ROSAT, H{alpha} line emission, and radial velocity measurement from high-resolution infrared spectra obtained at Infrared Telescope Facility. We confirm three of the candidates to be new members of the group: TYC 1186-706-1, TYC 7443-1102-1, and TYC 2211-1309-1 which are late-K and early-M dwarfs 45-60 pc from the Sun. We also identify a common proper motion companion to the known {beta} Pictoris Moving Group member TYC 7443-1102-1, at a 26.''3 separation; the new companion is associated with the X-ray source 1RXS J195602.8 - 320720. We argue that the present technique could be applied to other large proper motion catalogs to identify most of the elusive, low-mass members of known nearby moving groups and associations.

  6. Deep Mantle Structure As a Reference Frame for Absolute Plate Motions

    NASA Astrophysics Data System (ADS)

    Torsvik, T. H.; Van Der Voo, R.; Doubrovine, P. V.; Burke, K. C.; Steinberger, B. M.; Domeier, M.

    2014-12-01

    Since the Pangea supercontinent formed some 320 million years ago, the majority of large igneous provinces and diamond-bearing rocks (kimberlites) near Earth's surface can be sourced to plumes erupting from the margins of two large thermochemical reservoirs at the core-mantle boundary. Using this surface to core-mantle boundary correlation to locate continents in longitude and a new iterative approach for defining a paleomagnetic reference frame corrected for true polar wander, we present a model for plate motion back to earliest Paleozoic time (540 Ma). We have identified six phases of slow, oscillatory true polar wander during the Paleozoic. True polar wander rates (<1 Degree/Myr) are compatible to those in the Mesozoic but plate velocities are on average twice as high. We show that a geologically reasonable model that reconstructs continents in longitude in such a way that large igneous provinces and kimberlites are positioned above the plume generation zones at the times of their formation can be successfully applied to the entire Phanerozoic. Our model is a kinematic model for only the continents. The next step in improving it will be developing a model for the entire lithosphere, including synthetic oceanic lithosphere. This is challenging, but we will demonstrate a full-plate model back to the Late Paleozoic (410 Ma).

  7. Ground-based CCD astrometry with wide field imagers. III. WFI@2.2m proper-motion catalog of the globular cluster ω Centauri

    NASA Astrophysics Data System (ADS)

    Bellini, A.; Piotto, G.; Bedin, L. R.; Anderson, J.; Platais, I.; Momany, Y.; Moretti, A.; Milone, A. P.; Ortolani, S.

    2009-01-01

    Context: ω Centauri is the most well studied Galactic Globular Cluster because of its numerous puzzling features: significant dispersion in metallicity, multiple populations, triple main-sequence, horizontal branch morphology, He-rich population(s), and extended star-formation history. Intensive spectroscopic follow-up observing campaigns targeting stars at different positions in the color-magnitude diagram promises to clarify some of these peculiarities. Aims: To be able to target cluster members reliably during spectroscopic surveys and both spatial and radial distributions in the cluster outskirts without including field stars, a high quality proper-motion catalog of ω Cen and membership probability determination are required. The only available wide field proper-motion catalog of ω Cen is derived from photographic plates, and only for stars brighter than B~16. Using ESO archive data, we create a new, CCD-based, proper-motion catalog for this cluster, extending to B~20. Methods: We used high precision astrometric software developed specifically for data acquired by WFI@2.2m telescope and presented in the first paper of this series. We demonstrated previously that a 7 mas astrometric precision level can be achieved with this telescope and camera for well exposed stars in a single exposure, assuming an empirical PSF and a local transformation approach in measuring star displacements. Results: We achieved a good cluster-field separation with a temporal base-line of only four years. We corrected our photometry for sky-concentration effects. We provide calibrated photometry for UBVR_CIC wide-band data plus narrow-band filter data centered on Hα for almost 360 000 stars. We confirm that the ω Cen metal-poor and metal-rich components have the same proper motion, and demonstrate that the metal-intermediate component in addition exhibits the same mean motion as the other RGB stars. We provide membership probability determinations for published ω Cen variable star

  8. Documentation for the machine readable version of the Yale Catalogue of the Positions and Proper Motions of Stars between Declinations -60 deg and -70 deg (Fallon 1983)

    NASA Technical Reports Server (NTRS)

    Roman, N. G.; Warren, W. H., Jr.

    1984-01-01

    The machine-readable, character-coded version of the catalog, as it is currently being distributed from the Astronomical Data Center(ADC), is described. The format and data provided in the magnetic tape version differ somewhat from those of the published catalog, which was also produced from a tape prepared at the ADC. The primary catalog data are positions and proper motions (equinox 1950.0) for 14597 stars.

  9. Under proper control, oxidation of proteins with known chemical structure provides an accurate and absolute method for the determination of their molar concentration.

    PubMed

    Guermant, C; Azarkan, M; Smolders, N; Baeyens-Volant, D; Nijs, M; Paul, C; Brygier, J; Vincentelli, J; Looze, Y

    2000-01-01

    Oxidation at 120 degrees C of inorganic and organic (including amino acids, di- and tripeptides) model compounds by K(2)Cr(2)O(7) in the presence of H(2)SO(4) (mass fraction: 0.572), Ag(2)SO(4) (catalyst), and HgSO(4) results in the quantitative conversion of their C-atoms into CO(2) within 24 h or less. Under these stressed, well-defined conditions, the S-atoms present in cysteine and cystine residues are oxidized into SO(3) while, interestingly, the oxidation states of all the other (including the N-) atoms normally present in a protein do remain quite unchanged. When the chemical structure of a given protein is available, the total number of electrons the protein is able to transfer to K(2)Cr(2)O(7) and thereof, the total number of moles of Cr(3+) ions which the protein is able to generate upon oxidation can be accurately calculated. In such cases, unknown protein molar concentrations can thus be determined through straightforward spectrophotometric measurements of Cr(3+) concentrations. The values of molar absorption coefficients for several well-characterized proteins have been redetermined on this basis and observed to be in excellent agreement with the most precise values reported in the literature, which fully assesses the validity of the method. When applied to highly purified proteins of known chemical structure (more generally of known atomic composition), this method is absolute and accurate (+/-1%). Furthermore, it is well adapted to series measurements since available commercial kits for chemical oxygen demand (COD) measurements can readily be adapted to work under the experimental conditions recommended here for the protein assay. PMID:10610688

  10. UKIDSS detections of cool brown dwarfs. Proper motions of 14 known >T5 dwarfs and discovery of three new T5.5-T6 dwarfs

    NASA Astrophysics Data System (ADS)

    Scholz, R.-D.; Bihain, G.; Schnurr, O.; Storm, J.

    2012-05-01

    Aims: We contribute to improving the census of cool brown dwarfs (late-T and Y dwarfs) in the immediate solar neighbourhood. Methods: By combining near-infrared (NIR) data of UKIDSS with mid-infrared WISE and other available NIR (2MASS) and red optical (SDSS z-band) multi-epoch data we detected high proper motion (HPM) objects with colours typical of late spectral types (>T5). We used NIR low-resolution spectroscopy for the classification of new candidates. Results: We determined new proper motions for 14 known T5.5-Y0 dwarfs, many of which are significantly (>2-10 times) more accurate than previous ones. We detected three new candidates, ULAS J0954+0623, ULAS J1152+0359, and ULAS J1204-0150, by their HPMs and colours. Using previously published and new UKIDSS positions of the known nearby T8 dwarf WISE J0254+0223 we improved its trigonometric parallax to 165 ± 20 mas. For the three new objects we obtained NIR spectroscopic follow-up with LBT/LUCIFER classifying them as T5.5 and T6 dwarfs. With their estimated spectroscopic distances of about 25-30 pc, their proper motions of about 430-650 mas/yr lead to tangential velocities of about 50-80 km s-1, typical of the Galactic thin-disk population. Based on observations with the Large Binocular Telescope (LBT)Tables 1-5 are available in electronic form at http://www.aanda.org

  11. VERY LONG BASELINE INTERFEROMETRY MEASURED PROPER MOTION AND PARALLAX OF THE γ-RAY MILLISECOND PULSAR PSR J0218+4232

    SciTech Connect

    Du, Yuanjie; Chen, Ding; Yang, Jun; Campbell, Robert M.; Janssen, Gemma; Stappers, Ben

    2014-02-20

    PSR J0218+4232 is a millisecond pulsar (MSP) with a flux density ∼0.9 mJy at 1.4 GHz. It is very bright in the high-energy X-ray and γ-ray domains. We conducted an astrometric program using the European VLBI Network (EVN) at 1.6 GHz to measure its proper motion and parallax. A model-independent distance would also help constrain its γ-ray luminosity. We achieved a detection of signal-to-noise ratio S/N >37 for the weak pulsar in all five epochs. Using an extragalactic radio source lying 20 arcmin away from the pulsar, we estimate the pulsar's proper motion to be μ{sub α}cos δ = 5.35 ± 0.05 mas yr{sup –1} and μ{sub δ} = –3.74 ± 0.12 mas yr{sup –1}, and a parallax of π = 0.16 ± 0.09 mas. The very long baseline interferometry (VLBI) proper motion has significantly improved upon the estimates from long-term pulsar timing observations. The VLBI parallax provides the first model-independent distance constraints: d=6.3{sub −2.3}{sup +8.0} kpc, with a corresponding 3σ lower-limit of d = 2.3 kpc. This is the first pulsar trigonometric parallax measurement based solely on EVN observations. Using the derived distance, we believe that PSR J0218+4232 is the most energetic γ-ray MSP known to date. The luminosity based on even our 3σ lower-limit distance is high enough to pose challenges to the conventional outer gap and slot gap models.

  12. Identifications and limited spectroscopy for Luyten common proper motion stars with probable white dwarf components. I - Pair brighter than 17th magnitude

    NASA Technical Reports Server (NTRS)

    Oswalt, Terry D.; Hintzen, Paul M.; Luyten, Willem J.

    1988-01-01

    Identifications are provided for 103 bright Luyten common proper motion (CPM) stellar systems with m(pg) less than 17.0 mag containing likely white dwarf (WD) components. New spectral types are presented for 55 components, and spectral types for 51 more are available in the literature. With the CPM systems previously published by Giclas et al. (1978), the Luyten stars provide a uniform sample of nearly 200 pairs or multiples brighter than 17h magnitude. Selection effects biasing the combined samples are discussed; in particular, evidence is presented that fewer than 1 percent of wide WD binaries have been detected.

  13. G 112-29 (=NLTT 18149): A Very Wide Companion to GJ 282 AB with a Common Proper Motion, Common Parallax, Common Radial Velocity, and Common Age

    NASA Astrophysics Data System (ADS)

    Poveda, A.; Allen, Christine; Costero, R.; Echevarría, J.; Hernández-Alcántara, A.

    2009-11-01

    We have made a search for common proper motion (CPM) companions to the wide binaries in the solar vicinity. We found that the binary GJ 282AB has a very distant CPM companion (NLTT 18149) at a separation s = 1fdg09. Improved spectral types and radial velocities are obtained, and ages determined for the three components. The Hipparcos trigonometric parallaxes and the new radial velocities and ages turn out to be very similar for the three stars, and provide strong evidence that they form a physical system. At a projected separation of 55,733 AU from GJ 282AB, NLTT 18149 ranks among the widest physical companions known.

  14. G 112-29 (=NLTT 18149): A VERY WIDE COMPANION TO GJ 282 AB WITH A COMMON PROPER MOTION, COMMON PARALLAX, COMMON RADIAL VELOCITY, AND COMMON AGE

    SciTech Connect

    Poveda, A.; Allen, Christine; Costero, R.; EchevarrIa, J.; Hernandez-Alcantara, A.

    2009-11-20

    We have made a search for common proper motion (CPM) companions to the wide binaries in the solar vicinity. We found that the binary GJ 282AB has a very distant CPM companion (NLTT 18149) at a separation s = 1.{sup 0}09. Improved spectral types and radial velocities are obtained, and ages determined for the three components. The Hipparcos trigonometric parallaxes and the new radial velocities and ages turn out to be very similar for the three stars, and provide strong evidence that they form a physical system. At a projected separation of 55,733 AU from GJ 282AB, NLTT 18149 ranks among the widest physical companions known.

  15. Proper Brushing

    MedlinePlus

    ... 3 teeth using a vibrating back & forth rolling motion. A rolling motion is when the brush makes contact with the ... gumline. Gently brush using back, forth, and rolling motion along all of the inner tooth surfaces. Tilt ...

  16. Spectroscopy of New High Proper Motion Stars in the Northern Sky. I. New Nearby Stars, New High-Velocity Stars, and an Enhanced Classification Scheme for M Dwarfs

    NASA Astrophysics Data System (ADS)

    Lépine, Sébastien; Rich, R. Michael; Shara, Michael M.

    2003-03-01

    We define an enhanced spectral classification scheme for M dwarf stars and use it to derive spectral classification of 104 northern stars with proper motions larger than 0.5" yr-1 that we discovered in a survey of high proper motion stars at low Galactic latitudes. The final tally is as follows: 54 M dwarfs, 25 sdK and sdM subdwarfs, 14 esdK and esdM extreme subdwarfs, and 11 DA and DC white dwarfs. Among the most interesting cases, we find one star to be the coolest subdwarf ever reported (LSR 2036+5059, with spectral type sdM7.5), a new M9.0 dwarf only about 6 pc distant (LSR 1835+3259), and a new M6.5 dwarf only 7 pc from the Sun (LSR 2124+4003). Spectroscopic distances suggests that 27 of the M dwarfs, three of the white dwarfs, and one of the subdwarfs (LSR 2036+5059) are within 25 pc of the Sun, making them excellent candidates for inclusion in the solar neighborhood census. Estimated sky-projected velocities suggest that most of our subdwarfs and extreme subdwarfs have halo kinematics. We find that several white dwarfs and non-metal-poor M dwarfs also have kinematics consistent with the halo, and we briefly discuss their possible origin.

  17. Paleomagnetic Euler Poles and the Apparent Polar Wander and Absolute Motion of North America Since the Carboniferous

    NASA Astrophysics Data System (ADS)

    Gordon, Richard G.; Cox, Allan; O'Hare, Scott

    1984-10-01

    spot Euler pole for 200-90 Ma lies only 15° outside the 95% confidence ellipsoid of the paleomagnetic Euler pole. The good but not perfect agreement reflects displacement between the hot spot and paleomagnetic reference frames at an average rate that is smaller by an order of magnitude than the rate at which the faster plates are moving. The angular velocity of North America about the Jurassic-Cretaceous paleomagnetic Euler pole was determined by plotting the angular positions of paleomagnetic poles along the track as a function of age. For the Cretaceous the angular velocity was too small to measure. During the Jurassic the angular velocity was high, corresponding to a root-mean-square velocity of 70 km/m.y. for the North American plate. A short time interval of even more rapid movement during the Middle and Late Jurassic, possibly corresponding to the beginning of rapid displacement between North America and Africa, is suggested by the data. The direction of absolute motion of North America during the Jurassic was toward the northwest. A Carboniferous-Permian-Triassic paleomagnetic Euler pole was determined from 26 paleomagnetic poles. The progression of poles along this track is consistent with known ages and stratigraphy, except for some systematic differences between poles from Triassic rocks on the Colorado Plateau and poles from Triassic rocks off the Colorado Plateau. These differences could be due to a small clockwise rotation of the Colorado Plateau with respect to cratonal North America, or to miscorrelations between Triassic rocks on the Colorado Plateau and off the Colorado Plateau, or to large lag times between the deposition and magnetization of some rock units, or to some combination of these possibilities. Despite these ambiguities in interpreting paleomagnetic data from Triassic rocks, the general pattern of apparent polar wander and plate motion during the Carboniferous through Triassic is clear: The root-mean-square velocity of North America was

  18. ON THE DETECTABILITY OF A PREDICTED MESOLENSING EVENT ASSOCIATED WITH THE HIGH PROPER MOTION STAR VB 10

    SciTech Connect

    Lepine, Sebastien; DiStefano, Rosanne E-mail: rd@cfa.harvard.edu

    2012-04-10

    Extrapolation of the astrometric motion of the nearby low-mass star VB 10 indicates that sometime in late 2011 December or during the first 2-3 months of 2012, the star will make a close approach to a background point source. Based on astrometric uncertainties, we estimate a 1 in 2 chance that the distance of closest approach {rho}{sub min} will be less than 100 mas, a 1 in 5 chance that {rho}{sub min} < 50 mas, and a 1 in 10 chance that {rho}{sub min} < 20 mas. The last would result in a microlensing event with a 6% magnification in the light from the background source and an astrometric shift of 3.3 mas. The lensing signal will however be significantly diluted by the light from VB 10, which is 1.5 mag brighter than the background source in B band, 5 mag brighter in I band, and 10 mag brighter in K band, making the event undetectable in all but the bluer optical bands. However, we show that if VB 10 happens to harbor a {approx}1 M{sub J} planet on a moderately wide ( Almost-Equal-To 0.18 AU-0.84 AU) orbit, there is a chance (1% to more than 10%, depending on the distance of closest approach and orbital period and inclination) that a passage of the planet closer to the background source will result in a secondary event of higher magnification. The detection of secondary events could be made possible with a several-times-per-night multi-site monitoring campaign.

  19. The VMC survey. IX. Pilot study of the proper motion of stellar populations in the LMC from 2MASS and VISTA data

    NASA Astrophysics Data System (ADS)

    Cioni, M.-R. L.; Girardi, L.; Moretti, M. I.; Piffl, T.; Ripepi, V.; Rubele, S.; Scholz, R.-D.; Bekki, K.; Clementini, G.; Ivanov, V. D.; Oliveira, J. M.; van Loon, J. Th.

    2014-02-01

    Context. Proper motion (PM) studies are fundamental ingredients in the understanding of the orbital history of galaxies. Current measurements do not yet provide a satisfactory answer to the possible scenarios for the formation and evolution of the Magellanic Clouds and of the Bridge and Stream that link them with each other and with our Galaxy. Aims: We use multi-epoch near-infrared observations from the VISTA survey of the Magellanic Cloud system (VMC) to measure the PM of stars of the Large Magellanic Cloud (LMC), in one tile of 1.5 deg2 centred at (α,δ) = (05:59:23.136, -66:20:28.68) and including the south ecliptic pole, with respect to their Two Micron All Sky Survey (2MASS) position over a time baseline of about 10 years. Proper motions from VMC observations only, spanning a time range of about 1 year, are also derived. Methods: Stars of different ages are selected from the colour-magnitude diagram, (J - Ks) vs. Ks, and their average coordinate displacement is computed from the difference between Ks band observations from VMC and 2MASS or among VMC data alone for stars as faint as Ks = 19 mag. Proper motions are derived by averaging up to seven 2MASS-VMC combinations in the first case and from the slope of the best-fit line among the seven VMC epochs in the second case. Separate PM values are obtained for Cepheids, RR Lyrae stars, long period variables, and eclipsing binary stars in the field. Results: The PM of ~40 000 LMC stars in the tile, with respect to ~8000 background galaxies, obtained from VMC data alone, is μαcos (δ) = +2.20 ± 0.06 (stat) ±0.29 (sys) and μδ = +1.70 ± 0.06 (stat) ±0.30 (sys) mas yr-1. This value agrees with recent ground-based determinations, but is larger than studies with the Hubble Space Telescope; this discrepancy may be due to additional systematic errors in the data. Our result implies either higher tangential motion or higher internal motion, or a combination of these, although we cannot discuss these possibilities

  20. PROPER MOTIONS OF THE ARCHES CLUSTER WITH KECK LASER GUIDE STAR ADAPTIVE OPTICS: THE FIRST KINEMATIC MASS MEASUREMENT OF THE ARCHES

    SciTech Connect

    Clarkson, W. I.; Ghez, A. M.; Morris, M. R.; Yelda, S.; Lu, J. R.; Stolte, A.; McCrady, N.; Do, T.

    2012-06-01

    We report the first detection of the intrinsic velocity dispersion of the Arches cluster-a young ({approx}2 Myr), massive (10{sup 4} M{sub Sun }) starburst cluster located only 26 pc in projection from the Galactic center. This was accomplished using proper motion measurements within the central 10'' Multiplication-Sign 10'' of the cluster, obtained with the laser guide star adaptive optics system at Keck Observatory over a three-year time baseline (2006-2009). This uniform data set results in proper motion measurements that are improved by a factor {approx}5 over previous measurements from heterogeneous instruments. By careful, simultaneous accounting of the cluster and field contaminant distributions as well as the possible sources of measurement uncertainties, we estimate the internal velocity dispersion to be 0.15 {+-} 0.01 mas yr{sup -1}, which corresponds to 5.4 {+-} 0.4 km s{sup -1} at a distance of 8.4 kpc. Projecting a simple model for the cluster onto the sky to compare with our proper motion data set, in conjunction with surface density data, we estimate the total present-day mass of the cluster to be M(r < 1.0 pc) = 1.5{sup +0.74}{sub -0.60} Multiplication-Sign 10{sup 4} M{sub Sun }. The mass in stars observed within a cylinder of radius R (for comparison to photometric estimates) is found to be M(R < 0.4 pc) = 0.90{sup +0.40}{sub -0.35} Multiplication-Sign 10{sup 4} M{sub Sun} at formal 3{sigma} confidence. This mass measurement is free from assumptions about the mass function of the cluster, and thus may be used to check mass estimates from photometry and simulation. Photometric mass estimates assuming an initially Salpeter mass function ({Gamma}{sub 0} = 1.35, or {Gamma} {approx} 1.0 at present, where dN/d(log M){proportional_to}M{sup {Gamma}}) suggest a total cluster mass M{sub cl} {approx} (4-6) Multiplication-Sign 10{sup 4} M{sub Sun} and projected mass ({approx} 2 {<=} M(R < 0.4 pc) {<=} 3) Multiplication-Sign 10{sup 4} M{sub Sun }. Photometric

  1. Investigation of the open star cluster NGC 2323 (M50) based on the proper motions and photometry of its constituent stars

    NASA Astrophysics Data System (ADS)

    Frolov, V. N.; Ananjevskaja, Yu. K.; Polyakov, E. V.

    2012-02-01

    The results of a comprehensive study of the Galactic open cluster NGC 2323 (M50) are presented. The positions of stars to a limiting magnitude {ie74-1} in a {ie74-2} area centered on the cluster were measured on six plates from the Pulkovo normal astrograph with a maximum epoch difference of 60 yr. The measurements were performed with the Pulkovo "Fantasy" automated measuring system upgraded in 2010. The corresponding areas from the USNO-A2.0, USNO-B1, and 2MASS catalogues were used as additional plates. As a result, the relative proper motions of stars were obtained with a root-mean-square error of 5.85 mas yr-1. A catalogue of UBV and JHK magnitudes for objects in the investigated area was compiled from available published resources. The astrometric selection of cluster members was made by the maximum likelihood method. A high individual cluster membership probability of a star ( P ≥ 80%) served as the first selection criterion. The position of a star on the photometric color-magnitude ( V ∝ ( B-V), J ∝ ( J-K)) diagrams of the cluster was considered as the second criterion. The position of an object on the color-color (( U-B)-( B-V), ( J-H)-( J-K)) diagrams served as the third criterion. On the basis of these criteria, it was established that 508 stars are members of NGC 2323. These data were used to refine the physical parameters of the cluster: the mean reddening {ie74-3}, the true distance modulus {ie74-4}, and the cluster age of about 140 Myr from the grid of isochrones computed by the Padova group for solar chemical composition. Two tables contain the catalogues of proper motions and photometry for stars in the area. The luminosity and mass functions were constructed. The cluster membership of red and blue giants, variable, double, and multiple stars was considered. The position of the cluster center was improved: {ie74-5}, δ = -08°20'16″(2000.0).

  2. DISCOVERY OF FOUR HIGH PROPER MOTION L DWARFS, INCLUDING A 10 pc L DWARF AT THE L/T TRANSITION {sup ,}

    SciTech Connect

    Castro, Philip J.; Gizis, John E.; Harris, Hugh C.; Mace, Gregory N.; McLean, Ian S.; Kirkpatrick, J. Davy; Pattarakijwanich, Petchara; Skrutskie, Michael F. E-mail: gizis@udel.edu

    2013-10-20

    We discover four high proper motion L dwarfs by comparing the Wide-field Infrared Survey Explorer (WISE) to the Two Micron All Sky Survey. WISE J140533.32+835030.5 is an L dwarf at the L/T transition with a proper motion of 0.85 ± 0.''02 yr{sup –1}, previously overlooked due to its proximity to a bright star (V ≈ 12 mag). From optical spectroscopy we find a spectral type of L8, and from moderate-resolution J band spectroscopy we find a near-infrared spectral type of L9. We find WISE J140533.32+835030.5 to have a distance of 9.7 ± 1.7 pc, bringing the number of L dwarfs at the L/T transition within 10 pc from six to seven. WISE J040137.21+284951.7, WISE J040418.01+412735.6, and WISE J062442.37+662625.6 are all early L dwarfs within 25 pc, and were classified using optical and low-resolution near-infrared spectra. WISE J040418.01+412735.6 is an L2 pec (red) dwarf, a member of the class of unusually red L dwarfs. We use follow-up optical and low-resolution near-infrared spectroscopy to classify a previously discovered fifth object WISEP J060738.65+242953.4 as an (L8 Opt/L9 NIR), confirming it as an L dwarf at the L/T transition within 10 pc. WISEP J060738.65+242953.4 shows tentative CH{sub 4} in the H band, possibly the result of unresolved binarity with an early T dwarf, a scenario not supported by binary spectral template fitting. If WISEP J060738.65+242953.4 is a single object, it represents the earliest onset of CH{sub 4} in the H band of an L/T transition dwarf in the SpeX Library. As very late L dwarfs within 10 pc, WISE J140533.32+835030.5 and WISEP J060738.65+242953.4 will play a vital role in resolving outstanding issues at the L/T transition.

  3. Study on The Difference Between Proper-Motion of Halpha line emission and Non-Thermal X-Ray emission In Supernova Remnants

    NASA Astrophysics Data System (ADS)

    Shimoda, Jiro; Ohira, Yutaka; Yamazaki, Ryo; Inoue, Tsuyoshi; Soeda, Masanobu

    Balmer line emission (Halpha) by neutral hydrogen and X-ray synchrotron emission by accelerated electrons are observed from some supernova remnants (SNRs), which are thought as accelerators of galactic cosmic rays (CRs). From these observations, the cosmic ray acceleration efficiency is estimated. According to the theory of diffusive shock acceleration (DSA), electrons are accelerated around the shock front, and emit the synchrotron radiation. Measurement of proper motion of the synchrotron X-rays gives the shock velocity. At the same time, we can estimate the post shock temperature from the line width of Halpha emission, because neutral hydrogen collide with downstream hot protons and exchange their charge, so that the hot neutral component arises. In the specific case of a SNR RCW86, measured expansion speed of Halpha filament is about 1200km/s (Helder et al. 2013), while 6000km/s in X-rays (Helder et al. 2009). It is expected that the emission regions of the Halpha and the synchrotron X-rays are different. However, they are overlaid in the same line of sight. In this study, using three dimensional magnetohydrodynamics (MHD) simulations, we consider propagation of supernova blast wave shock in realistic inhomogeneous interstellar medium. Interaction between the upstream density inhomogeneity and the shock wave causes rippled shock structure and fluctuation of local shock velocity.We show that our synthetic observations of the MHD simulation data are consistent with actual observation results for RCW86.

  4. Proper Flossing

    MedlinePlus

    Proper Flossing Flossing is an essential part of the tooth-cleaning process because it removes plaque from between teeth and at the gumline, where periodontal disease often begins. If you find using floss awkward or difficult, ask your dental hygienist about ...

  5. Easy Absolute Values? Absolutely

    ERIC Educational Resources Information Center

    Taylor, Sharon E.; Mittag, Kathleen Cage

    2015-01-01

    The authors teach a problem-solving course for preservice middle-grades education majors that includes concepts dealing with absolute-value computations, equations, and inequalities. Many of these students like mathematics and plan to teach it, so they are adept at symbolic manipulations. Getting them to think differently about a concept that they…

  6. VLBI FOR GRAVITY PROBE B. III. A LIMIT ON THE PROPER MOTION OF THE 'CORE' OF THE QUASAR 3C 454.3

    SciTech Connect

    Bartel, N.; Bietenholz, M. F.; Ransom, R. R.; Lebach, D. E.; Ratner, M. I.; Shapiro, I. I.; Lederman, J. I.; Petrov, L.

    2012-07-01

    We made very long baseline interferometry observations at 8.4 GHz between 1997 and 2005 to estimate the coordinates of the 'core' component of the superluminal quasar, 3C 454.3, the ultimate reference point in the distant universe for the NASA/Stanford Gyroscope Relativity Mission, Gravity Probe B (GP-B). These coordinates are determined relative to those of the brightness peaks of two other compact extragalactic sources, B2250+194 and B2252+172, nearby on the sky, and within a celestial reference frame (CRF), defined by a large suite of compact extragalactic radio sources, and nearly identical to the International Celestial Reference Frame 2 (ICRF2). We find that B2250+194 and B2252+172 are stationary relative to each other, and also in the CRF, to within 1{sigma} upper limits of 15 and 30 {mu}as yr{sup -1} in {alpha} and {delta}, respectively. The core of 3C 454.3 appears to jitter in its position along the jet direction over {approx}0.2 mas, likely due to activity close to the putative supermassive black hole nearby, but on average is stationary in the CRF within 1{sigma} upper limits on its proper motion of 39 {mu}as yr{sup -1} (1.0c) and 30 {mu}as yr{sup -1} (0.8c) in {alpha} and {delta}, respectively, for the period 2002-2005. Our corresponding limit over the longer interval, 1998-2005, of more importance to GP-B, is 46 and 56 {mu}as yr{sup -1} in {alpha} and {delta}, respectively. Some of 3C 454.3's jet components show significantly superluminal motion with speeds of up to {approx}200 {mu}as yr{sup -1} or 5c in the CRF. The core of 3C 454.3 thus provides for GP-B a sufficiently stable reference in the distant universe.

  7. Hubble Space Telescope Proper Motion (HSTPROMO) Catalogs of Galactic Globular Clusters. IV. Kinematic Profiles and Average Masses of Blue Straggler Stars

    NASA Astrophysics Data System (ADS)

    Baldwin, A. T.; Watkins, L. L.; van der Marel, R. P.; Bianchini, P.; Bellini, A.; Anderson, J.

    2016-08-01

    We make use of the Hubble Space Telescope proper-motion catalogs derived by Bellini et al. to produce the first radial velocity dispersion profiles σ (R) for blue straggler stars (BSSs) in Galactic globular clusters (GCs), as well as the first dynamical estimates for the average mass of the entire BSS population. We show that BSSs typically have lower velocity dispersions than stars with mass equal to the main-sequence turnoff mass, as one would expect for a more massive population of stars. Since GCs are expected to experience some degree of energy equipartition, we use the relation σ \\propto {M}-η , where η is related to the degree of energy equipartition, along with our velocity dispersion profiles to estimate BSS masses. We estimate η as a function of cluster relaxation from recent Monte Carlo cluster simulations by Bianchini et al. and then derive an average mass ratio {M}{BSS}/{M}{MSTO}=1.50+/- 0.14 and an average mass {M}{BSS}=1.22+/- 0.12 M ⊙ from 598 BSSs across 19 GCs. The final error bars include any systematic errors that are random between different clusters, but not any potential biases inherent to our methodology. Our results are in good agreement with the average mass of {M}{BSS}=1.22+/- 0.06 M ⊙ for the 35 BSSs in Galactic GCs in the literature with properties that have allowed individual mass determination. Based on proprietary and archival observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by AURA, Inc., under NASA contract NAS 5-26555.

  8. Datirovka zvezdnogo kataloga Ptolemeya po sobstvennym dvizheniyam: tysyacheletnyaya problema reshena %t Dating Ptolemy's star catalogue based on proper motions: the thousand-year-old problem solved

    NASA Astrophysics Data System (ADS)

    Dambis, A. K.; Efremov, Yu. N.

    The thousand-year-old problem of the origin of the star catalogue included in Ptolemy's "Almagest" is considered. The dilemma whether stellar coordinates were based on Hipparchus' or Ptolemy's observations has arisen long ago, because the 1 degree error in ecliptic longitudes may be explained either by Ptolemy's error in the initial longitudes of the Sun, or by the fact that Ptolemy adopted the original Hipparchus' coordinates and transformed them to a 265-year later epoch using an erroneous constant for precession. In fact, only indirect evidence for the Hipparchan origin of most of the coordinates was available so far, and most specialists considered the issue still to be resolved. We have successfully applied a new approach based on stellar proper motions. The time-dependent mutual distances in the configurations including 8 fast stars yield an epoch of -53 ± 130 B.C., whereas the bulk method based on an analysis of the Almagest minus computed coordinate differences for 40 fastest stars yields an epoch of -90 ± 120 B.C. Standard errors in the ancient ecliptic longitudes and latitudes are found to be σ(λcosβ) = 18' and σβ = 13', respectively. It is concluded that the stellar coordinates in the Almagest catalogue were observed during Hipparchus' lifetime and that Ptolemy's authorship claim can be rejected at a 94% significance level. Ptolemy's assertion that "we observed as many stars as we could sight down to the sixth magnitude" might simply imply that he found each star of the original catalogue to be near its position in the sky given by Hipparchus, and then adopted Hipparchus' coordinates as measured by a more skilled observer.

  9. THE SOLAR NEIGHBORHOOD. XXV. DISCOVERY OF NEW PROPER MOTION STARS WITH 0.''40 yr{sup -1} > {mu} {>=} 0.''18 yr{sup -1} BETWEEN DECLINATIONS -47{sup 0} AND 00{sup 0}

    SciTech Connect

    Boyd, Mark R.; Winters, Jennifer G.; Henry, Todd J.; Jao, Wei-Chun; Finch, Charlie T.; Subasavage, John P.; Hambly, Nigel C. E-mail: winters@chara.gsu.edu E-mail: jao@chara.gsu.edu E-mail: jsubasavage@ctio.noao.edu

    2011-07-15

    We present 2817 new southern proper motion systems with 0.''40 yr{sup -1} > {mu} {>=} 0.''18 yr{sup -1} and declination between -47{sup 0} and 00{sup 0}. This is a continuation of the SuperCOSMOS-RECONS (SCR) proper motion searches of the southern sky. We use the same photometric relations as previous searches to provide distance estimates based on the assumption that the objects are single main-sequence stars. We find 79 new red dwarf systems predicted to be within 25 pc, including a few new components of previously known systems. Two systems-SCR 1731-2452 at 9.5 pc and SCR 1746-3214 at 9.9 pc-are anticipated to be within 10 pc. We also find 23 new white dwarf (WD) candidates with distance estimates of 15-66 pc, as well as 360 new red subdwarf candidates. With this search, we complete the SCR sweep of the southern sky for stars with {mu} {>=} 0.''18 yr{sup -1} and R{sub 59F} {<=} 16.5, resulting in a total of 5042 objects in 4724 previously unreported proper motion systems. Here we provide selected comprehensive lists from our SCR proper motion search to date, including 152 red dwarf systems estimated to be within 25 pc (9 within 10 pc), 46 WDs (10 within 25 pc), and 598 subdwarf candidates. The results of this search suggest that there are more nearby systems to be found at fainter magnitudes and lower proper motion limits than those probed so far.

  10. The Solar Neighborhood. XXV. Discovery of New Proper Motion Stars with 0.40 sec/yr > mu > or = 0.18 sec/yr Between Declinations -47 deg and 00 deg

    NASA Technical Reports Server (NTRS)

    Boyd, Mark R.; Winters, Jennifer G.; Henry, Todd J.; Jao, Wei-Chun; Finch, Charlie T.; Subasavage, John P.; Hambly, Nigel C.

    2011-01-01

    We present 2817 new southern proper motion systems with 0.40 sec/yr > mu > or = 0.18 sec/yr and declination between 47 deg and 00 deg. This is a continuation of the SuperCOSMOS-RECONS (SCR) proper motion searches of the southern sky. We use the same photometric relations as previous searches to provide distance estimates based on the assumption that the objects are single main-sequence stars. We find 79 new red dwarf systems predicted to be within 25 pc, including a few new components of previously known systems. Two systems--SCR 1731-2452 at 9.5 pc and SCR 1746-3214 at 9.9 pc--are anticipated to be within 10 pc. We also find 23 new white dwarf (WD) candidates with distance estimates of 15-66 pc, as well as 360 new red subdwarf candidates. With this search, we complete the SCR sweep of the southern sky for stars with mu > or = 0.18 sec/yr and R(sub 59F) < or = 16.5, resulting in a total of 5042 objects in 4724 previously unreported proper motion systems. Here we provide selected comprehensive lists from our SCR proper motion search to date, including 152 red dwarf systems estimated to be within 25 pc (9 within 10 pc), 46 WDs (10 within 25 pc), and 598 subdwarf candidates. The results of this search suggest that there are more nearby systems to be found at fainter magnitudes and lower proper motion limits than those probed so far.

  11. THE DIRECTLY IMAGED PLANET AROUND THE YOUNG SOLAR ANALOG 1RXS J160929.1 - 210524: CONFIRMATION OF COMMON PROPER MOTION, TEMPERATURE, AND MASS

    SciTech Connect

    Lafreniere, David; Jayawardhana, Ray; Van Kerkwijk, Marten H.

    2010-08-10

    Giant planets are usually thought to form within a few tens of AU of their host stars, and hence it came as a surprise when we found what appeared to be a planetary mass ({approx}0.008 M {sub sun}) companion around the 5 Myr old solar mass star 1RXS J160929.1 - 210524 in the Upper Scorpius association. At the time, we took the object's membership in Upper Scorpius-established from near-infrared, H- and K-band spectroscopy-and its proximity (2.''2 or 330 AU) to the primary as strong evidence for companionship, but could not verify their common proper motion. Here, we present follow-up astrometric measurements that confirm that the companion is indeed comoving with the primary star, which we interpret as evidence that it is a truly bound planetary mass companion. We also present new J-band spectroscopy and 3.0-3.8 {mu}m photometry of the companion. Based on a comparison with model spectra, these new measurements are consistent with the previous estimate of the companion effective temperature of 1800 {+-} 200 K. We present a new estimate of the companion mass based on evolution models and the calculated bolometric luminosity of the companion; we obtain a value of 0.008{sup +0.003} {sub -0.002} M {sub sun}, again consistent with our previous result. Finally, we present angular differential imaging observations of the system allowing us to rule out additional planets in the system more massive than 1 M {sub Jup}, 2 M {sub Jup}, and 8 M {sub Jup} at projected separations larger than 3'' ({approx}440 AU), 0.''7 ({approx}100 AU), and 0.''35 ({approx}50 AU), respectively. This companion is the least massive known to date at such a large orbital distance; it shows that objects in the planetary mass range exist at orbital separations of several hundred AU, posing a serious challenge for current formation models.

  12. Documentation for the machine-readable version of the AGK3 Star Catalogue of Positions and Proper Motions North of -2 deg .5 declination (Dieckvoss and Collaborators 1975)

    NASA Technical Reports Server (NTRS)

    Warren, W. H., Jr.

    1984-01-01

    A detailed description of the machine-readable astronomical catalog as it is currently being distributed from the Astronomical Data Center is given. Stellar motions and positions are listed herein in tabular form.

  13. TH-C-BRD-08: Reducing the Effect of Respiratory Motion On the Delivered Dose in Proton Therapy Through Proper Field Angle Selection

    SciTech Connect

    Matney, J; Park, P; Court, L; Zhu, X; Li, H; Mohan, R; Liu, W; Dong, L

    2014-06-15

    Purpose: This work investigated a novel planning strategy of selecting radiotherapy beam angles that minimizes the change in water equivalent thickness (dWET) during respiration in order to reduce the effects of respiratory motion in passively scattered proton therapy (PSPT). Methods: In a clinical trial treating locally-advanced lung cancer with proton therapy, 2–4 co-planar beams were previously selected by dosimetrists in the design of physician-approved PSPT treatment plans. The authors identified a cohort of patients in which respiratory motion affected the planned PSPT dose delivery. For this cohort, this work analyzed dWET during respiration over a 360 degree arc of potential treatment angles around the patient: the dWET was defined as the difference in WET between the full-exhale (T50) and full-inhale (T0) phases of the simulation 4DCT. New PSPT plans were redesigned by selecting new beam angles that demonstrated significant reduction in the value of dWET. Between the T50 and T0 phases, the root-mean-square deviation of dose and the change in dose-volume histogram curves (dAUC) for anatomical structures were calculated to compare the original to dWET reduction plans. Results: To date, three plans were retrospectively redesigned based on dWET analysis. In the dWET reduction plan, the root mean square dose (T50-T0) was reduced by 15–35% and the DVH dAUC values were reduced by more than 60%.The PSPT plans redesigned by selecting appropriate field angles to minimize dWET demonstrated less dosimetric variation due to respiration. Conclusion: We have introduced the use of a new metric to quantify respiratory motion in proton therapy: dWET. The use of dWET allows us to minimize the impact of respiratory motion of the entire anatomy in the beam path. This work is a proof of principle that dWET could suggest field angles in proton therapy that are more robust to the effects of respiratory motion.

  14. The Duck Redux: An Improved Proper-Motion Upper Limit for the Pulsar B1757-24 near the Supernova Remnant G5.4-1.2

    NASA Astrophysics Data System (ADS)

    Blazek, J. A.; Gaensler, B. M.; Chatterjee, S.; van der Swaluw, E.; Camilo, F.; Stappers, B. W.

    2006-12-01

    ``The Duck'' is a complicated nonthermal radio system, consisting of the energetic radio pulsar B1757-24, its surrounding pulsar wind nebula G5.27-0.90, and the adjacent supernova remnant (SNR) G5.4-1.2. PSR B1757-24 was originally claimed to be a young (~15,000 yr) and extreme-velocity (>~1500 km s-1) pulsar, which had penetrated and emerged from the shell of the associated SNR G5.4-1.2 but recent upper limits on the pulsar's motion have raised serious difficulties with this interpretation. We here present 8.5 GHz interferometric observations of the nebula G5.27-0.90 over a 12 yr baseline, doubling the time span of previous measurements. These data correspondingly allow us to halve the previous upper limit on the nebula's westward motion to 14 mas yr-1 (5 σ), allowing a substantive reevaluation of this puzzling object. We rule out the possibility that the pulsar and SNR were formed from a common supernova explosion ~15,000 yr ago, as implied by the pulsar's characteristic age, but conclude that an old (>~70,000 yr) pulsar/SNR association, or a situation in which the pulsar and SNR are physically unrelated, are both still viable explanations.

  15. Motion.

    ERIC Educational Resources Information Center

    Gerhart, James B.; Nussbaum, Rudi H.

    This monograph was written for the Conference on the New Instructional Materials in Physics held at the University of Washington in summer, 1965. It is intended for use in an introductory course in college physics. It consists of an extensive qualitative discussion of motion followed by a detailed development of the quantitative methods needed to…

  16. Motion.

    ERIC Educational Resources Information Center

    Brand, Judith, Ed.

    2002-01-01

    This issue of Exploratorium Magazine focuses on the topic of motion. Contents include: (1) "First Word" (Zach Tobias); (2) "Cosmic Collisions" (Robert Irion); (3) "The Mobile Cell" (Karen E. Kalumuck); (4) "The Paths of Paths" (Steven Vogel); (5) "Fragments" (Pearl Tesler); (6) "Moving Pictures" (Amy Snyder); (7) "Plants on the Go" (Katharine…

  17. Real-Time Cosmology with Gaia: Developing the Theory to Use Extragalactic Proper Motions to Make Dynamical Cosmological Tests, to Measure Geometric Distances, and to Detect Primordial Gravitational Waves

    NASA Astrophysics Data System (ADS)

    Darling, Jeremy

    A new field of study, "real-time cosmology," is now possible. This involves observing a dynamic universe that can be seen to change over human timescales. Most cosmological observations are geometrical, using standard candles or rulers to measure the expansion history and curvature as light propagates through the universe. Real-time cosmological measurements are dynamical, revealing the changing geometry of the universe - thus often providing geometrical distances independent of the canonical cosmological distance ladder - and are typically orthogonal to customary cosmological tests. This field of inquiry is no longer far-fetched, and this proposal demonstrates using extant data that many types of measurement are now within a factor of a few of being detectable, but the theory will very soon lag the observational capabilities. The Gaia mission will provide astrometry and proper motions of roughly 100 microarcseconds per year for half a million quasars by the end of its 5-year mission, but the theory for how to employ these data for cosmological tests has not been established. This project will develop the theory, models, and methods needed to make optimal use of the Gaia extragalactic proper motion measurements and to make significant new cosmological tests, distance measurements, and mass measurements. Gaia data can provide rich cosmological tests that are nearly model-independent. This work will build the theoretical framework enabling Gaia to measure or constrain: (1) The real-time growth and recession of structures, providing mass and distance measurements, (2) Extragalactic parallax for a statistical sample and individual galaxies, thus providing geometric distances, (3) The primordial stochastic long-period gravitational wave background, which deflects quasar light in a quadrupolar proper motion pattern, and (4) Cosmic shear, rotation, bulk motion, and local voids that may manifest as an apparent acceleration attributed to dark energy. One can also test the

  18. Absolute Zero

    NASA Astrophysics Data System (ADS)

    Donnelly, Russell J.; Sheibley, D.; Belloni, M.; Stamper-Kurn, D.; Vinen, W. F.

    2006-12-01

    Absolute Zero is a two hour PBS special attempting to bring to the general public some of the advances made in 400 years of thermodynamics. It is based on the book “Absolute Zero and the Conquest of Cold” by Tom Shachtman. Absolute Zero will call long-overdue attention to the remarkable strides that have been made in low-temperature physics, a field that has produced 27 Nobel Prizes. It will explore the ongoing interplay between science and technology through historical examples including refrigerators, ice machines, frozen foods, liquid oxygen and nitrogen as well as much colder fluids such as liquid hydrogen and liquid helium. A website has been established to promote the series: www.absolutezerocampaign.org. It contains information on the series, aimed primarily at students at the middle school level. There is a wealth of material here and we hope interested teachers will draw their student’s attention to this website and its substantial contents, which have been carefully vetted for accuracy.

  19. Absolute Summ

    NASA Astrophysics Data System (ADS)

    Phillips, Alfred, Jr.

    Summ means the entirety of the multiverse. It seems clear, from the inflation theories of A. Guth and others, that the creation of many universes is plausible. We argue that Absolute cosmological ideas, not unlike those of I. Newton, may be consistent with dynamic multiverse creations. As suggested in W. Heisenberg's uncertainty principle, and with the Anthropic Principle defended by S. Hawking, et al., human consciousness, buttressed by findings of neuroscience, may have to be considered in our models. Predictability, as A. Einstein realized with Invariants and General Relativity, may be required for new ideas to be part of physics. We present here a two postulate model geared to an Absolute Summ. The seedbed of this work is part of Akhnaton's philosophy (see S. Freud, Moses and Monotheism). Most important, however, is that the structure of human consciousness, manifest in Kenya's Rift Valley 200,000 years ago as Homo sapiens, who were the culmination of the six million year co-creation process of Hominins and Nature in Africa, allows us to do the physics that we do. .

  20. Proper Interval Vertex Deletion

    NASA Astrophysics Data System (ADS)

    Villanger, Yngve

    Deleting a minimum number of vertices from a graph to obtain a proper interval graph is an NP-complete problem. At WG 2010 van Bevern et al. gave an O((14k + 14) k + 1 kn 6) time algorithm by combining iterative compression, branching, and a greedy algorithm. We show that there exists a simple greedy O(n + m) time algorithm that solves the Proper Interval Vertex Deletion problem on \\{claw,net,allowbreak tent,allowbreak C_4,C_5,C_6\\}-free graphs. Combining this with branching on the forbidden structures claw,net,tent,allowbreak C_4,C_5, and C 6 enables us to get an O(kn 6 6 k ) time algorithm for Proper Interval Vertex Deletion, where k is the number of deleted vertices.

  1. PROPER: Optical propagation routines

    NASA Astrophysics Data System (ADS)

    Krist, John E.

    2014-05-01

    PROPER simulates the propagation of light through an optical system using Fourier transform algorithms (Fresnel, angular spectrum methods). Distributed as IDL source code, it includes routines to create complex apertures, aberrated wavefronts, and deformable mirrors. It is especially useful for the simulation of high contrast imaging telescopes (extrasolar planet imagers like TPF).

  2. Teaching Absolute Value Meaningfully

    ERIC Educational Resources Information Center

    Wade, Angela

    2012-01-01

    What is the meaning of absolute value? And why do teachers teach students how to solve absolute value equations? Absolute value is a concept introduced in first-year algebra and then reinforced in later courses. Various authors have suggested instructional methods for teaching absolute value to high school students (Wei 2005; Stallings-Roberts…

  3. Calculating proper transfer prices

    SciTech Connect

    Dorkey, F.C. ); Jarrell, G.A. )

    1991-01-01

    This article deals with developing a proper transfer pricing method. Decentralization is as American as baseball. While managers laud the widespread benefits of both decentralization and baseball, they often greet the term transfer price policy with a yawn. Since transfer prices are as critical to the success of decentralized firms as good pitchers are to baseball teams, this is quite a mistake on the part of our managers. A transfer price is the price charged to one division for a product or service that another division produced or provided. In many, perhaps most, decentralized organizations, the transfer pricing policies actually used are grossly inefficient and sacrifice the potential advantages of decentralization. Experience shows that far too many companies have transfer pricing policies that cost them significantly in foregone growth and profits.

  4. Eosinophil count - absolute

    MedlinePlus

    Eosinophils; Absolute eosinophil count ... the white blood cell count to give the absolute eosinophil count. ... than 500 cells per microliter (cells/mcL). Normal value ranges may vary slightly among different laboratories. Talk ...

  5. Proper Stellar Direction and Astronomical Aberration

    NASA Astrophysics Data System (ADS)

    Crosta, Mariateresa; Vecchiato, A.

    2009-05-01

    The general relativistic definition of astrometric measurement needs an appropriate use of the concept of reference frame, which should then be linked to the conventions of the IAU Resolutions (IAU, 2000), which fix the celestial coordinate system. A consistent definition of the astrometric observables in the context of General Relativity is also essential to find uniquely the stellar coordinates and proper motion, this being the main physical task of the inverse ray tracing problem. Aim of this presentation is to set the level of reciprocal consistency of two relativistic models, GREM and RAMOD (Gaia, ESA mission), in order to guarantee a physically correct definition of light direction to a star, an essential item for deducing the star coordinates and proper motion within the same level of measurement accuracy.

  6. Proper stellar directions and astronomical aberration

    NASA Astrophysics Data System (ADS)

    Crosta, Mariateresa; Vecchiato, Alberto

    2010-01-01

    The general relativistic definition of astrometric measurement needs an appropriate use of the concept of reference frame, which should then be linked to the conventions of the IAU Resolutions (Soffel et al., 2003), which fix the celestial coordinate system. A consistent definition of the astrometric observables in the context of General Relativity is also essential to find uniquely the stellar coordinates and proper motion, this being the main physical task of the inverse ray tracing problem. Aim of this work is to set the level of reciprocal consistency of two relativistic models, GREM and RAMOD (Gaia, ESA mission), in order to guarantee a physically correct definition of light direction to a star, an essential item for deducing the star coordinates and proper motion within the same level of measurement accuracy.

  7. Absolute nuclear material assay

    DOEpatents

    Prasad, Manoj K.; Snyderman, Neal J.; Rowland, Mark S.

    2012-05-15

    A method of absolute nuclear material assay of an unknown source comprising counting neutrons from the unknown source and providing an absolute nuclear material assay utilizing a model to optimally compare to the measured count distributions. In one embodiment, the step of providing an absolute nuclear material assay comprises utilizing a random sampling of analytically computed fission chain distributions to generate a continuous time-evolving sequence of event-counts by spreading the fission chain distribution in time.

  8. Absolute nuclear material assay

    DOEpatents

    Prasad, Manoj K.; Snyderman, Neal J.; Rowland, Mark S.

    2010-07-13

    A method of absolute nuclear material assay of an unknown source comprising counting neutrons from the unknown source and providing an absolute nuclear material assay utilizing a model to optimally compare to the measured count distributions. In one embodiment, the step of providing an absolute nuclear material assay comprises utilizing a random sampling of analytically computed fission chain distributions to generate a continuous time-evolving sequence of event-counts by spreading the fission chain distribution in time.

  9. Fundamental Principles of Proper Space Kinematics

    NASA Astrophysics Data System (ADS)

    Wade, Sean

    It is desirable to understand the movement of both matter and energy in the universe based upon fundamental principles of space and time. Time dilation and length contraction are features of Special Relativity derived from the observed constancy of the speed of light. Quantum Mechanics asserts that motion in the universe is probabilistic and not deterministic. While the practicality of these dissimilar theories is well established through widespread application inconsistencies in their marriage persist, marring their utility, and preventing their full expression. After identifying an error in perspective the current theories are tested by modifying logical assumptions to eliminate paradoxical contradictions. Analysis of simultaneous frames of reference leads to a new formulation of space and time that predicts the motion of both kinds of particles. Proper Space is a real, three-dimensional space clocked by proper time that is undergoing a densification at the rate of c. Coordinate transformations to a familiar object space and a mathematical stationary space clarify the counterintuitive aspects of Special Relativity. These symmetries demonstrate that within the local universe stationary observers are a forbidden frame of reference; all is in motion. In lieu of Quantum Mechanics and Uncertainty the use of the imaginary number i is restricted for application to the labeling of mass as either material or immaterial. This material phase difference accounts for both the perceived constant velocity of light and its apparent statistical nature. The application of Proper Space Kinematics will advance more accurate representations of microscopic, oscopic, and cosmological processes and serve as a foundation for further study and reflection thereafter leading to greater insight.

  10. Proper-time relativistic dynamics

    NASA Technical Reports Server (NTRS)

    Gill, Tepper L.; Zachary, W. W.; Lindesay, James

    1993-01-01

    Proper-time relativistic single-particle classical Hamiltonian mechanics is formulated using a transformation from observer time to system proper time which is a canonical contact transformation on extended phase space. It is shown that interaction induces a change in the symmetry structure of the system which can be analyzed in terms of a Lie-isotopic deformation of the algebra of observables.

  11. Proper Names: Reference and Attribution

    ERIC Educational Resources Information Center

    Maumus, Michael Fletcher

    2012-01-01

    In the wake of Saul Kripke's landmark "Naming and Necessity," the claim that proper names are directly referential expressions devoid of descriptive content has come to verge on philosophical commonplace. Nevertheless, the return to a purely referential semantics for proper names has coincided with the resurgence of the very puzzles…

  12. Absolute biological needs.

    PubMed

    McLeod, Stephen

    2014-07-01

    Absolute needs (as against instrumental needs) are independent of the ends, goals and purposes of personal agents. Against the view that the only needs are instrumental needs, David Wiggins and Garrett Thomson have defended absolute needs on the grounds that the verb 'need' has instrumental and absolute senses. While remaining neutral about it, this article does not adopt that approach. Instead, it suggests that there are absolute biological needs. The absolute nature of these needs is defended by appeal to: their objectivity (as against mind-dependence); the universality of the phenomenon of needing across the plant and animal kingdoms; the impossibility that biological needs depend wholly upon the exercise of the abilities characteristic of personal agency; the contention that the possession of biological needs is prior to the possession of the abilities characteristic of personal agency. Finally, three philosophical usages of 'normative' are distinguished. On two of these, to describe a phenomenon or claim as 'normative' is to describe it as value-dependent. A description of a phenomenon or claim as 'normative' in the third sense does not entail such value-dependency, though it leaves open the possibility that value depends upon the phenomenon or upon the truth of the claim. It is argued that while survival needs (or claims about them) may well be normative in this third sense, they are normative in neither of the first two. Thus, the idea of absolute need is not inherently normative in either of the first two senses. PMID:23586876

  13. The absolute path command

    2012-05-11

    The ap command traveres all symlinks in a given file, directory, or executable name to identify the final absolute path. It can print just the final path, each intermediate link along with the symlink chan, and the permissions and ownership of each directory component in the final path. It has functionality similar to "which", except that it shows the final path instead of the first path. It is also similar to "pwd", but it canmore » provide the absolute path to a relative directory from the current working directory.« less

  14. The absolute path command

    SciTech Connect

    Moody, A.

    2012-05-11

    The ap command traveres all symlinks in a given file, directory, or executable name to identify the final absolute path. It can print just the final path, each intermediate link along with the symlink chan, and the permissions and ownership of each directory component in the final path. It has functionality similar to "which", except that it shows the final path instead of the first path. It is also similar to "pwd", but it can provide the absolute path to a relative directory from the current working directory.

  15. THE ABSOLUTE MAGNITUDE OF RRc VARIABLES FROM STATISTICAL PARALLAX

    SciTech Connect

    Kollmeier, Juna A.; Burns, Christopher R.; Thompson, Ian B.; Preston, George W.; Crane, Jeffrey D.; Madore, Barry F.; Morrell, Nidia; Prieto, José L.; Shectman, Stephen; Simon, Joshua D.; Villanueva, Edward; Szczygieł, Dorota M.; Gould, Andrew; Sneden, Christopher; Dong, Subo

    2013-09-20

    We present the first definitive measurement of the absolute magnitude of RR Lyrae c-type variable stars (RRc) determined purely from statistical parallax. We use a sample of 242 RRc variables selected from the All Sky Automated Survey for which high-quality light curves, photometry, and proper motions are available. We obtain high-resolution echelle spectra for these objects to determine radial velocities and abundances as part of the Carnegie RR Lyrae Survey. We find that M{sub V,RRc} = 0.59 ± 0.10 at a mean metallicity of [Fe/H] = –1.59. This is to be compared with previous estimates for RRab stars (M{sub V,RRab} = 0.76 ± 0.12) and the only direct measurement of an RRc absolute magnitude (RZ Cephei, M{sub V,RRc} = 0.27 ± 0.17). We find the bulk velocity of the halo relative to the Sun to be (W{sub π}, W{sub θ}, W{sub z} ) = (12.0, –209.9, 3.0) km s{sup –1} in the radial, rotational, and vertical directions with dispersions (σ{sub W{sub π}},σ{sub W{sub θ}},σ{sub W{sub z}}) = (150.4, 106.1, 96.0) km s{sup -1}. For the disk, we find (W{sub π}, W{sub θ}, W{sub z} ) = (13.0, –42.0, –27.3) km s{sup –1} relative to the Sun with dispersions (σ{sub W{sub π}},σ{sub W{sub θ}},σ{sub W{sub z}}) = (67.7,59.2,54.9) km s{sup -1}. Finally, as a byproduct of our statistical framework, we are able to demonstrate that UCAC2 proper-motion errors are significantly overestimated as verified by UCAC4.

  16. The Meaning of Proper Names.

    ERIC Educational Resources Information Center

    Saka, Paul

    The two major schools of thought concerned with the meaning of proper names, i.e., the direct-reference or referrential/causal theory, and the description theory, are outlined, and new arguments are presented for a strong version of the second of these theories. The referential theory takes the meaning of the name as being the same as its…

  17. The Proper Study of Psychology.

    ERIC Educational Resources Information Center

    Gibson, Eleanor J.

    1997-01-01

    Reed believes the proper study of psychology is not mind or stimulus-response phenomena but ways animals (including humans) encounter the world. In this view, animals are seen in environmental and evolutionary contexts; a fundamental concept is not mind or behavior but affordance or what environments offer animals; and new topics, such as…

  18. Electronic Absolute Cartesian Autocollimator

    NASA Technical Reports Server (NTRS)

    Leviton, Douglas B.

    2006-01-01

    An electronic absolute Cartesian autocollimator performs the same basic optical function as does a conventional all-optical or a conventional electronic autocollimator but differs in the nature of its optical target and the manner in which the position of the image of the target is measured. The term absolute in the name of this apparatus reflects the nature of the position measurement, which, unlike in a conventional electronic autocollimator, is based absolutely on the position of the image rather than on an assumed proportionality between the position and the levels of processed analog electronic signals. The term Cartesian in the name of this apparatus reflects the nature of its optical target. Figure 1 depicts the electronic functional blocks of an electronic absolute Cartesian autocollimator along with its basic optical layout, which is the same as that of a conventional autocollimator. Referring first to the optical layout and functions only, this or any autocollimator is used to measure the compound angular deviation of a flat datum mirror with respect to the optical axis of the autocollimator itself. The optical components include an illuminated target, a beam splitter, an objective or collimating lens, and a viewer or detector (described in more detail below) at a viewing plane. The target and the viewing planes are focal planes of the lens. Target light reflected by the datum mirror is imaged on the viewing plane at unit magnification by the collimating lens. If the normal to the datum mirror is parallel to the optical axis of the autocollimator, then the target image is centered on the viewing plane. Any angular deviation of the normal from the optical axis manifests itself as a lateral displacement of the target image from the center. The magnitude of the displacement is proportional to the focal length and to the magnitude (assumed to be small) of the angular deviation. The direction of the displacement is perpendicular to the axis about which the

  19. The proper use of acetaminophen

    PubMed Central

    James, Laura; Sullivan, Janice E; Roberts, Dean

    2011-01-01

    Acetaminophen (N-acetyl-p-aminophenol, paracetamol [APAP])-induced acute liver failure is the most common cause of acute liver failure in adults. In children, APAP accounts for 25% of all cases of acute liver failure. The high mortality rate associated with this preventable condition makes it vital that paediatricians are aware of the potential adverse effects associated with this widely used drug. While APAP is generally considered to be safe when used as directed, its inclusion in multiple over-the-counter medications, as well as in prescription drugs, mandates that physicians promote and educate the general public about the proper use of acetaminophen in children. PMID:23115492

  20. ABSOLUTE POLARIMETRY AT RHIC.

    SciTech Connect

    OKADA; BRAVAR, A.; BUNCE, G.; GILL, R.; HUANG, H.; MAKDISI, Y.; NASS, A.; WOOD, J.; ZELENSKI, Z.; ET AL.

    2007-09-10

    Precise and absolute beam polarization measurements are critical for the RHIC spin physics program. Because all experimental spin-dependent results are normalized by beam polarization, the normalization uncertainty contributes directly to final physics uncertainties. We aimed to perform the beam polarization measurement to an accuracy Of {Delta}P{sub beam}/P{sub beam} < 5%. The absolute polarimeter consists of Polarized Atomic Hydrogen Gas Jet Target and left-right pairs of silicon strip detectors and was installed in the RHIC-ring in 2004. This system features proton-proton elastic scattering in the Coulomb nuclear interference (CNI) region. Precise measurements of the analyzing power A{sub N} of this process has allowed us to achieve {Delta}P{sub beam}/P{sub beam} = 4.2% in 2005 for the first long spin-physics run. In this report, we describe the entire set up and performance of the system. The procedure of beam polarization measurement and analysis results from 2004-2005 are described. Physics topics of AN in the CNI region (four-momentum transfer squared 0.001 < -t < 0.032 (GeV/c){sup 2}) are also discussed. We point out the current issues and expected optimum accuracy in 2006 and the future.

  1. Implants as absolute anchorage.

    PubMed

    Rungcharassaeng, Kitichai; Kan, Joseph Y K; Caruso, Joseph M

    2005-11-01

    Anchorage control is essential for successful orthodontic treatment. Each tooth has its own anchorage potential as well as propensity to move when force is applied. When teeth are used as anchorage, the untoward movements of the anchoring units may result in the prolonged treatment time, and unpredictable or less-than-ideal outcome. To maximize tooth-related anchorage, techniques such as differential torque, placing roots into the cortex of the bone, the use of various intraoral devices and/or extraoral appliances have been implemented. Implants, as they are in direct contact with bone, do not possess a periodontal ligament. As a result, they do not move when orthodontic/orthopedic force is applied, and therefore can be used as "absolute anchorage." This article describes different types of implants that have been used as orthodontic anchorage. Their clinical applications and limitations are also discussed. PMID:16463910

  2. Absolute Equilibrium Entropy

    NASA Technical Reports Server (NTRS)

    Shebalin, John V.

    1997-01-01

    The entropy associated with absolute equilibrium ensemble theories of ideal, homogeneous, fluid and magneto-fluid turbulence is discussed and the three-dimensional fluid case is examined in detail. A sigma-function is defined, whose minimum value with respect to global parameters is the entropy. A comparison is made between the use of global functions sigma and phase functions H (associated with the development of various H-theorems of ideal turbulence). It is shown that the two approaches are complimentary though conceptually different: H-theorems show that an isolated system tends to equilibrium while sigma-functions allow the demonstration that entropy never decreases when two previously isolated systems are combined. This provides a more complete picture of entropy in the statistical mechanics of ideal fluids.

  3. The National Geodetic Survey absolute gravity program

    NASA Astrophysics Data System (ADS)

    Peter, George; Moose, Robert E.; Wessells, Claude W.

    1989-03-01

    The National Geodetic Survey absolute gravity program will utilize the high precision afforded by the JILAG-4 instrument to support geodetic and geophysical research, which involves studies of vertical motions, identification and modeling of other temporal variations, and establishment of reference values. The scientific rationale of these objectives is given, the procedures used to collect gravity and environmental data in the field are defined, and the steps necessary to correct and remove unwanted environmental effects are stated. In addition, site selection criteria, methods of concomitant environmental data collection and relative gravity observations, and schedule and logistics are discussed.

  4. Absolute neutrino mass measurements

    NASA Astrophysics Data System (ADS)

    Wolf, Joachim

    2011-10-01

    The neutrino mass plays an important role in particle physics, astrophysics and cosmology. In recent years the detection of neutrino flavour oscillations proved that neutrinos carry mass. However, oscillation experiments are only sensitive to the mass-squared difference of the mass eigenvalues. In contrast to cosmological observations and neutrino-less double beta decay (0v2β) searches, single β-decay experiments provide a direct, model-independent way to determine the absolute neutrino mass by measuring the energy spectrum of decay electrons at the endpoint region with high accuracy. Currently the best kinematic upper limits on the neutrino mass of 2.2eV have been set by two experiments in Mainz and Troitsk, using tritium as beta emitter. The next generation tritium β-experiment KATRIN is currently under construction in Karlsruhe/Germany by an international collaboration. KATRIN intends to improve the sensitivity by one order of magnitude to 0.2eV. The investigation of a second isotope (137Rh) is being pursued by the international MARE collaboration using micro-calorimeters to measure the beta spectrum. The technology needed to reach 0.2eV sensitivity is still in the R&D phase. This paper reviews the present status of neutrino-mass measurements with cosmological data, 0v2β decay and single β-decay.

  5. Absolute neutrino mass measurements

    SciTech Connect

    Wolf, Joachim

    2011-10-06

    The neutrino mass plays an important role in particle physics, astrophysics and cosmology. In recent years the detection of neutrino flavour oscillations proved that neutrinos carry mass. However, oscillation experiments are only sensitive to the mass-squared difference of the mass eigenvalues. In contrast to cosmological observations and neutrino-less double beta decay (0v2{beta}) searches, single {beta}-decay experiments provide a direct, model-independent way to determine the absolute neutrino mass by measuring the energy spectrum of decay electrons at the endpoint region with high accuracy.Currently the best kinematic upper limits on the neutrino mass of 2.2eV have been set by two experiments in Mainz and Troitsk, using tritium as beta emitter. The next generation tritium {beta}-experiment KATRIN is currently under construction in Karlsruhe/Germany by an international collaboration. KATRIN intends to improve the sensitivity by one order of magnitude to 0.2eV. The investigation of a second isotope ({sup 137}Rh) is being pursued by the international MARE collaboration using micro-calorimeters to measure the beta spectrum. The technology needed to reach 0.2eV sensitivity is still in the R and D phase. This paper reviews the present status of neutrino-mass measurements with cosmological data, 0v2{beta} decay and single {beta}-decay.

  6. Proper alignment of the microscope.

    PubMed

    Rottenfusser, Rudi

    2013-01-01

    The light microscope is merely the first element of an imaging system in a research facility. Such a system may include high-speed and/or high-resolution image acquisition capabilities, confocal technologies, and super-resolution methods of various types. Yet more than ever, the proverb "garbage in-garbage out" remains a fact. Image manipulations may be used to conceal a suboptimal microscope setup, but an artifact-free image can only be obtained when the microscope is optimally aligned, both mechanically and optically. Something else is often overlooked in the quest to get the best image out of the microscope: Proper sample preparation! The microscope optics can only do its job when its design criteria are matched to the specimen or vice versa. The specimen itself, the mounting medium, the cover slip, and the type of immersion medium (if applicable) are all part of the total optical makeup. To get the best results out of a microscope, understanding the functions of all of its variable components is important. Only then one knows how to optimize these components for the intended application. Different approaches might be chosen to discuss all of the microscope's components. We decided to follow the light path which starts with the light source and ends at the camera or the eyepieces. To add more transparency to this sequence, the section up to the microscope stage was called the "Illuminating Section", to be followed by the "Imaging Section" which starts with the microscope objective. After understanding the various components, we can start "working with the microscope." To get the best resolution and contrast from the microscope, the practice of "Koehler Illumination" should be understood and followed by every serious microscopist. Step-by-step instructions as well as illustrations of the beam path in an upright and inverted microscope are included in this chapter. A few practical considerations are listed in Section 3. PMID:23931502

  7. Absolute Identification by Relative Judgment

    ERIC Educational Resources Information Center

    Stewart, Neil; Brown, Gordon D. A.; Chater, Nick

    2005-01-01

    In unidimensional absolute identification tasks, participants identify stimuli that vary along a single dimension. Performance is surprisingly poor compared with discrimination of the same stimuli. Existing models assume that identification is achieved using long-term representations of absolute magnitudes. The authors propose an alternative…

  8. Be Resolute about Absolute Value

    ERIC Educational Resources Information Center

    Kidd, Margaret L.

    2007-01-01

    This article explores how conceptualization of absolute value can start long before it is introduced. The manner in which absolute value is introduced to students in middle school has far-reaching consequences for their future mathematical understanding. It begins to lay the foundation for students' understanding of algebra, which can change…

  9. 7 CFR 29.112 - Proper light.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 2 2011-01-01 2011-01-01 false Proper light. 29.112 Section 29.112 Agriculture... INSPECTION Regulations Inspectors, Samplers, and Weighers § 29.112 Proper light. Tobacco shall not be inspected or sampled for the purposes of the Act except when displayed in proper light for...

  10. 7 CFR 29.112 - Proper light.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 2 2014-01-01 2014-01-01 false Proper light. 29.112 Section 29.112 Agriculture... INSPECTION Regulations Inspectors, Samplers, and Weighers § 29.112 Proper light. Tobacco shall not be inspected or sampled for the purposes of the Act except when displayed in proper light for...

  11. 7 CFR 29.112 - Proper light.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 2 2012-01-01 2012-01-01 false Proper light. 29.112 Section 29.112 Agriculture... INSPECTION Regulations Inspectors, Samplers, and Weighers § 29.112 Proper light. Tobacco shall not be inspected or sampled for the purposes of the Act except when displayed in proper light for...

  12. 7 CFR 29.112 - Proper light.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 2 2013-01-01 2013-01-01 false Proper light. 29.112 Section 29.112 Agriculture... INSPECTION Regulations Inspectors, Samplers, and Weighers § 29.112 Proper light. Tobacco shall not be inspected or sampled for the purposes of the Act except when displayed in proper light for...

  13. 7 CFR 29.112 - Proper light.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Proper light. 29.112 Section 29.112 Agriculture... INSPECTION Regulations Inspectors, Samplers, and Weighers § 29.112 Proper light. Tobacco shall not be inspected or sampled for the purposes of the Act except when displayed in proper light for...

  14. Proper Names a Cognitive-Philosophical Study

    ERIC Educational Resources Information Center

    Garcia-Ramirez, Eduardo

    2010-01-01

    Proper Names appear at the heart of several debates in philosophy and the cognitive sciences. These include "reference", "intentionality", and the nature of "belief" as well as "language acquisition", "cognitive development", and "memory". This dissertation follows a cognitive approach to the philosophical problems posed by proper names. It puts…

  15. Absolute transition probabilities of phosphorus.

    NASA Technical Reports Server (NTRS)

    Miller, M. H.; Roig, R. A.; Bengtson, R. D.

    1971-01-01

    Use of a gas-driven shock tube to measure the absolute strengths of 21 P I lines and 126 P II lines (from 3300 to 6900 A). Accuracy for prominent, isolated neutral and ionic lines is estimated to be 28 to 40% and 18 to 30%, respectively. The data and the corresponding theoretical predictions are examined for conformity with the sum rules.-

  16. How Does Force Affect Motion?

    ERIC Educational Resources Information Center

    Darling, Gerald

    2012-01-01

    Whether playing soccer at recess, walking to lunch, or sitting at their desk, children encounter forces every moment of their lives. The connection between force and motion is absolutely amazing to children, so anyone working with them better be prepared for the battery of tough questions they ask: "What made the ball move that way? Why does a…

  17. Gaia relativistic astrometric models. I. Proper stellar direction and aberration

    NASA Astrophysics Data System (ADS)

    Crosta, M.; Vecchiato, A.

    2010-01-01

    The high accuracy achievable by modern space astrometry requires the use of General Relativity to model the stellar light propagation through the gravitational field encountered from a source to a given observer inside the Solar System. The general relativistic definition of an astrometric measurement needs an appropriate use of the concept of reference frame, which should then be linked to the conventions of the IAU resolutions. On the other hand, a definition of the astrometric observables in the context of General Relativity is also essential for finding the stellar coordinates and proper motion uniquely, this being the main physical task of the inverse ray-tracing problem. The aim of this work is to set the level of reciprocal consistency of two relativistic models, GREM and RAMOD (Gaia, ESA mission), in order to guarantee a physically correct definition of the light's local direction to a star and deduce the star coordinates and proper motions at the level of accuracy required by these models consistently with the IAU's adopted reference systems.

  18. Large-scale databases of proper names.

    PubMed

    Conley, P; Burgess, C; Hage, D

    1999-05-01

    Few tools for research in proper names have been available--specifically, there is no large-scale corpus of proper names. Two corpora of proper names were constructed, one based on U.S. phone book listings, the other derived from a database of Usenet text. Name frequencies from both corpora were compared with human subjects' reaction times (RTs) to the proper names in a naming task. Regression analysis showed that the Usenet frequencies contributed to predictions of human RT, whereas phone book frequencies did not. In addition, semantic neighborhood density measures derived from the HAL corpus were compared with the subjects' RTs and found to be a better predictor of RT than was frequency in either corpus. These new corpora are freely available on line for download. Potentials for these corpora range from using the names as stimuli in experiments to using the corpus data in software applications. PMID:10495803

  19. How to Use Eye Drops Properly

    MedlinePlus

    ... Tablets, Suppositories, and Creams How to Use Eye Drops Properly (Using a mirror or having someone else ... gently squeeze the dropper so that a single drop falls into the pocket made by the lower ...

  20. Optomechanics for absolute rotation detection

    NASA Astrophysics Data System (ADS)

    Davuluri, Sankar

    2016-07-01

    In this article, we present an application of optomechanical cavity for the absolute rotation detection. The optomechanical cavity is arranged in a Michelson interferometer in such a way that the classical centrifugal force due to rotation changes the length of the optomechanical cavity. The change in the cavity length induces a shift in the frequency of the cavity mode. The phase shift corresponding to the frequency shift in the cavity mode is measured at the interferometer output to estimate the angular velocity of absolute rotation. We derived an analytic expression to estimate the minimum detectable rotation rate in our scheme for a given optomechanical cavity. Temperature dependence of the rotation detection sensitivity is studied.

  1. The Absolute Spectrum Polarimeter (ASP)

    NASA Technical Reports Server (NTRS)

    Kogut, A. J.

    2010-01-01

    The Absolute Spectrum Polarimeter (ASP) is an Explorer-class mission to map the absolute intensity and linear polarization of the cosmic microwave background and diffuse astrophysical foregrounds over the full sky from 30 GHz to 5 THz. The principal science goal is the detection and characterization of linear polarization from an inflationary epoch in the early universe, with tensor-to-scalar ratio r much greater than 1O(raised to the power of { -3}) and Compton distortion y < 10 (raised to the power of{-6}). We describe the ASP instrument and mission architecture needed to detect the signature of an inflationary epoch in the early universe using only 4 semiconductor bolometers.

  2. Absolute calibration of optical flats

    DOEpatents

    Sommargren, Gary E.

    2005-04-05

    The invention uses the phase shifting diffraction interferometer (PSDI) to provide a true point-by-point measurement of absolute flatness over the surface of optical flats. Beams exiting the fiber optics in a PSDI have perfect spherical wavefronts. The measurement beam is reflected from the optical flat and passed through an auxiliary optic to then be combined with the reference beam on a CCD. The combined beams include phase errors due to both the optic under test and the auxiliary optic. Standard phase extraction algorithms are used to calculate this combined phase error. The optical flat is then removed from the system and the measurement fiber is moved to recombine the two beams. The newly combined beams include only the phase errors due to the auxiliary optic. When the second phase measurement is subtracted from the first phase measurement, the absolute phase error of the optical flat is obtained.

  3. Asteroid proper elements and secular resonances

    NASA Technical Reports Server (NTRS)

    Knezevic, Zoran; Milani, Andrea

    1992-01-01

    In a series of papers (e.g., Knezevic, 1991; Milani and Knezevic, 1990; 1991) we reported on the progress we were making in computing asteroid proper elements, both as regards their accuracy and long-term stability. Additionally, we reported on the efficiency and 'intelligence' of our software. At the same time, we studied the associated problems of resonance effects, and we introduced the new class of 'nonlinear' secular resonances; we determined the locations of these secular resonances in proper-element phase space and analyzed their impact on the asteroid family classification. Here we would like to summarize the current status of our work and possible further developments.

  4. Evaluation of proper height for squatting stool.

    PubMed

    Jung, Hwa S; Jung, Hyung-Shik

    2008-05-01

    Many jobs and activities in people's daily lives have them in squatting postures. Jobs such as housekeeping, farming and welding require various squatting activities. It is speculated that prolonged squatting without any type of supporting stool would gradually and eventually impose musculoskeletal injuries on workers. This study aims to examine the proper height of the stool according to the position of working materials for the squatting worker. A total of 40 male and female college students and 10 female farmers participated in the experiment to find the proper stool height. Student participants were asked to sit and work in three different positions: floor level of 50 mm; ankle level of 200 mm; and knee level of 400 mm. They were then provided with stools of various heights and asked to maintain a squatting work posture. For each working position, they were asked to write down their thoughts on a preferred stool height. A Likert summated rating method as well as pairwise ranking test was applied to evaluate user preference for provided stools under conditions of different working positions. Under a similar experimental procedure, female farmers were asked to indicate their body part discomfort (BPD) on a body chart before and after performing the work. Statistical analysis showed that comparable results were found from both evaluation measures. When working position is below 50 mm, the proper stool height is 100 or should not be higher than 150 mm. When working position is 200 mm, the proper stool height is 150 mm. When working position is 400 mm, the proper stool height is 200 mm. Thus, it is strongly recommended to use proper height of stools with corresponding working position. Moreover, a wearable chair prototype was designed so that workers in a squatting posture do not have to carry and move the stool from one place to another. This stool should ultimately help to relieve physical stress and hence promote the health of squatting workers. This study sought

  5. Characterization of surface electromyography using time domain features for determining hand motion and stages of contraction.

    PubMed

    Bin Ahmad Nadzri, Ahmad Akmal; Ahmad, Siti Anom; Marhaban, Mohd Hamiruce; Jaafar, Haslina

    2014-03-01

    Surface electromyography (SEMG) signals can provide important information for prosthetic hand control application. In this study, time domain (TD) features were used in extracting information from the SEMG signal in determining hand motions and stages of contraction (start, middle and end). Data were collected from ten healthy subjects. Two muscles, which are flexor carpi ulnaris (FCU) and extensor carpi radialis (ECR) were assessed during three hand motions of wrist flexion (WF), wrist extension (WE) and co-contraction (CC). The SEMG signals were first segmented into 132.5 ms windows, full wave rectified and filtered with a 6 Hz low pass Butterworth filter. Five TD features of mean absolute value, variance, root mean square, integrated absolute value and waveform length were used for feature extraction and subsequently patterns were determined. It is concluded that the TD features that were used are able to differentiate hand motions. However, for the stages of contraction determination, although there were patterns observed, it is determined that the stages could not be properly be differentiated due to the variability of signal strengths between subjects. PMID:24443218

  6. Plate motion

    SciTech Connect

    Gordon, R.G. )

    1991-01-01

    The motion of tectonic plates on the earth is characterized in a critical review of U.S. research from the period 1987-1990. Topics addressed include the NUVEL-1 global model of current plate motions, diffuse plate boundaries and the oceanic lithosphere, the relation between plate motions and distributed deformations, accelerations and the steadiness of plate motions, the distribution of current Pacific-North America motion across western North America and its margin, plate reconstructions and their uncertainties, hotspots, and plate dynamics. A comprehensive bibliography is provided. 126 refs.

  7. Strategy Guideline: Proper Water Heater Selection

    SciTech Connect

    Hoeschele, M.; Springer, D.; German, A.; Staller, J.; Zhang, Y.

    2015-04-01

    This Strategy Guideline on proper water heater selection was developed by the Building America team Alliance for Residential Building Innovation to provide step-by-step procedures for evaluating preferred cost-effective options for energy efficient water heater alternatives based on local utility rates, climate, and anticipated loads.

  8. Strategy Guideline. Proper Water Heater Selection

    SciTech Connect

    Hoeschele, M.; Springer, D.; German, A.; Staller, J.; Zhang, Y.

    2015-04-09

    This Strategy Guideline on proper water heater selection was developed by the Building America team Alliance for Residential Building Innovation to provide step-by-step procedures for evaluating preferred cost-effective options for energy efficient water heater alternatives based on local utility rates, climate, and anticipated loads.

  9. 33 CFR 25.503 - Proper claimants.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... domiciliary of the foreign country. (b) A corporation or other organization doing business in a foreign country on a permanent basis may qualify as a proper claimant although organized under United States law... unless excluded by waiver provisions of applicable international agreements....

  10. Proper Values of Matrices and Some Applications.

    ERIC Educational Resources Information Center

    Amir-Moez, Ali R.

    1992-01-01

    Presents a short study of proper values of two-by-two matrices with real entries. Gives examples of symmetric matrices and applications to systems of linear equations of perpendicular lines intersecting at the origin and central conics rotated about the origin to eliminate the xy term from its equation. (MDH)

  11. The Essentials of Proper Wine Service.

    ERIC Educational Resources Information Center

    Manago, Gary H.

    This instructional unit was designed to assist the food services instructor and/or the restaurant manager in training students and/or staff in the proper procedure for serving wines to guests. The lesson plans included in this unit focus on: (1) the different types of wine glasses and their uses; (2) the parts of a wine glass; (3) the proper…

  12. Proper name hypermnesia in an autistic subject.

    PubMed

    Mottron, L; Belleville, S; Stip, E

    1996-06-01

    The case study of an autistic "savant" subject with person names hypermnesia is presented. NM's performance in memorizing person names is compared to that of normal controls, IQ-matched controls, and one overtrained control. The data show a selective hypermnesia for both the free recall of person names and the recognition of faces. Recall of common names and of biographical informations linked to faces is unremarkable. NM's hypermnesia is restricted to list learning as low performance is observed in face-name learning tasks. A comparison of the data with that of the overtrained control indicates that training is not responsible for NM's pattern of results. These findings, when combined with previous results involving proper names, demonstrate a double dissociation between proper names and other types of semantic and referential information. However, aspects of NM's performance pattern are more compatible with a network model of proper names than with a sequential model. We propose that the contextual regularity of proper names in ecological situations can be responsible for their high memorization by NM. PMID:8798332

  13. Joint moments of proper delay times

    SciTech Connect

    Martínez-Argüello, Angel M.; Martínez-Mares, Moisés; García, Julio C.

    2014-08-15

    We calculate negative moments of the N-dimensional Laguerre distribution for the orthogonal, unitary, and symplectic symmetries. These moments correspond to those of the proper delay times, which are needed to determine the statistical fluctuations of several transport properties through classically chaotic cavities, like quantum dots and microwave cavities with ideal coupling.

  14. Family Therapy: A Very Proper Failure.

    ERIC Educational Resources Information Center

    Midlarsky, Elizabeth

    This first-person account of a case study on family therapy discusses two latency-age boys who were referred for treatment. The assessment was that in both cases it was the family itself that was disturbed and needed treatment. The therapist worked with the first boy and his family together. The therapy model used was the "proper" family…

  15. The AFGL absolute gravity program

    NASA Technical Reports Server (NTRS)

    Hammond, J. A.; Iliff, R. L.

    1978-01-01

    A brief discussion of the AFGL's (Air Force Geophysics Laboratory) program in absolute gravity is presented. Support of outside work and in-house studies relating to gravity instrumentation are discussed. A description of the current transportable system is included and the latest results are presented. These results show good agreement with measurements at the AFGL site by an Italian system. The accuracy obtained by the transportable apparatus is better than 0.1 microns sq sec 10 microgal and agreement with previous measurements is within the combined uncertainties of the measurements.

  16. Proper Time Dynamics in General Relativity and Conformal Unified Theory

    NASA Astrophysics Data System (ADS)

    Gyngazov, L. N.; Pawlowski, M.; Pervushin, V. N.; Smirichinski, V. I.

    1998-12-01

    The paper is devoted to the description a measurable time-interval ("proper time") in the Hamiltonian version of general relativity with the Dirac-ADM metric. To separate the dynamical parameter of evolution from the space metric we use the Lichnerowicz conformally invariant variables. In terms of these variables GR is equivalent to the conformally invariant Penrose-Chernikov-Tagirov theory of a scalar field the role of which is played by the scale factor multiplied by the Planck constant. Identification of this scalar field with the modulus of the Higgs field in the standard model of electroweak and strong interactions allows us to formulate an example of conformally invariant unified theory where the vacuum averaging of the scalar field is determined by cosmological integrals of motion of the evolution of the universe.

  17. The tentative exploration of Shen Kuo's circle method and proper method

    NASA Astrophysics Data System (ADS)

    Guo, Shengchi

    In this paper, the circle method and proper method established by Shen Kuo, a famous scientist of Northern Song Dynasty, are discussed tentatively. This is a new approach for calculating the position of the sun on the ecliptic. The velocity of sun's annual apparent motion is regarded as the sum of a constant and a variation.

  18. The Solar Neighborhood. XIII. Parallax Results from the CTIOPI 0.9 Meter Program: Stars with μ >= 1.0" yr-1 (MOTION Sample)

    NASA Astrophysics Data System (ADS)

    Jao, Wei-Chun; Henry, Todd J.; Subasavage, John P.; Brown, Misty A.; Ianna, Philip A.; Bartlett, Jennifer L.; Costa, Edgardo; Méndez, René A.

    2005-04-01

    We present the first set of definitive trigonometric parallaxes and proper motions from the Cerro Tololo Inter-American Observatory Parallax Investigation. Full astrometric reductions for the program are discussed, including methods of reference star selection, differential color refraction corrections, and conversion of relative to absolute parallax. Using data acquired at the 0.9 m telescope at CTIO, full astrometric solutions and VRIJHKs photometry are presented for 36 red and white dwarf stellar systems with proper motions faster than 1.0" yr-1. Of these, 33 systems have their first ever trigonometric parallaxes, which comprise 41% of MOTION systems (those reported to have proper motions greater than 1.0" yr-1) south of δ=0deg that have no parallaxes. Four of the systems are new members of the RECONS 10 pc sample for which the first accurate trigonometric parallaxes are published here: DENIS J1048-3956 (4.04+/-0.03 pc), GJ 1128 (LHS 271, 6.53+/-0.10 pc), GJ 1068 (LHS 22, 6.97+/-0.09 pc), and GJ 1123 (LHS 263, 9.02+/-0.16 pc). In addition, two red subdwarf-white dwarf pairs, LHS 193AB and LHS 300AB, are identified. The white dwarf secondaries fall in a previously uncharted region of the H-R diagram.

  19. Effective density terms in proper integral equations

    NASA Astrophysics Data System (ADS)

    Dyer, Kippi M.; Perkyns, John S.; Pettitt, B. Montgomery

    2005-11-01

    Two complementary routes to a new integral equation theory for site-site molecular fluids are presented. First, a simple approximation to a subset of the atomic site bridge functions in the diagrammatically proper integral equation theory is presented. This in turn leads to a form analogous to the reactive fluid theory, in which the normalization of the intramolecular distribution function and the value of the off-diagonal elements in the density matrix of the proper integral equations are the means of propagating the bridge function approximation. Second, a derivation from a topological expansion of a model for the single-site activity followed by a topological reduction and low-order truncation is given. This leads to an approximate numerical value for the new density coefficient. The resulting equations give a substantial improvement over the standard construction as shown with a series of simple diatomic model calculations.

  20. Boltzmann babies in the proper time measure

    SciTech Connect

    Bousso, Raphael; Bousso, Raphael; Freivogel, Ben; Yang, I-Sheng

    2007-12-20

    After commenting briefly on the role of the typicality assumption in science, we advocate a phenomenological approach to the cosmological measure problem. Like any other theory, a measure should be simple, general, well defined, and consistent with observation. This allows us to proceed by elimination. As an example, we consider the proper time cutoff on a geodesic congruence. It predicts that typical observers are quantum fluctuations in the early universe, or Boltzmann babies. We sharpen this well-known youngness problem by taking into account the expansion and open spatial geometry of pocket universes. Moreover, we relate the youngness problem directly to the probability distribution for observables, such as the temperature of the cosmic background radiation. We consider a number of modifications of the proper time measure, but find none that would make it compatible with observation.

  1. Boltzmann babies in the proper time measure

    NASA Astrophysics Data System (ADS)

    Bousso, Raphael; Freivogel, Ben; Yang, I.-Sheng

    2008-05-01

    After commenting briefly on the role of the typicality assumption in science, we advocate a phenomenological approach to the cosmological measure problem. Like any other theory, a measure should be simple, general, well defined, and consistent with observation. This allows us to proceed by elimination. As an example, we consider the proper time cutoff on a geodesic congruence. It predicts that typical observers are quantum fluctuations in the early universe, or Boltzmann babies. We sharpen this well-known youngness problem by taking into account the expansion and open spatial geometry of pocket universes. Moreover, we relate the youngness problem directly to the probability distribution for observables, such as the temperature of the cosmic background radiation. We consider a number of modifications of the proper time measure, but find none that would make it compatible with observation.

  2. Testing effects for common versus proper names.

    PubMed

    Sensenig, Amanda E; Littrell-Baez, Megan K; Delosh, Edward L

    2011-08-01

    The present study examines the testing effect as a function of item meaningfulness. In Experiments 1 and 2 participants studied lists of words that could serve as proper names or occupations (e.g., Mr Baker or baker), with the items given in a name context for one group and an occupation context for a second group. During an intervening phase participants restudied some items and were given a cued recall test (Experiment 1) or a free recall test (Experiment 2) on other items. On a final free recall test memory was better for tested items than studied items in both the name and occupation contexts. Experiment 3 followed the same procedure as Experiment 1, except that participants studied lists of proper names that do not have alternative uses in the English language (e.g., Mr Anderson) or studied concrete nouns (e.g., letter). Tested items were better remembered on a final test than studied items, and there was no interaction with type of study material. These results show that the testing effect extends to proper names, material that is commonly assumed to differ from common names on several dimensions. PMID:21919593

  3. Closed-loop step motor control using absolute encoders

    SciTech Connect

    Hicks, J.S.; Wright, M.C.

    1997-08-01

    A multi-axis, step motor control system was developed to accurately position and control the operation of a triple axis spectrometer at the High Flux Isotope Reactor (HFIR) located at Oak Ridge National Laboratory. Triple axis spectrometers are used in neutron scattering and diffraction experiments and require highly accurate positioning. This motion control system can handle up to 16 axes of motion. Four of these axes are outfitted with 17-bit absolute encoders. These four axes are controlled with a software feedback loop that terminates the move based on real-time position information from the absolute encoders. Because the final position of the actuator is used to stop the motion of the step motors, the moves can be made accurately in spite of the large amount of mechanical backlash from a chain drive between the motors and the spectrometer arms. A modified trapezoidal profile, custom C software, and an industrial PC, were used to achieve a positioning accuracy of 0.00275 degrees of rotation. A form of active position maintenance ensures that the angles are maintained with zero error or drift.

  4. Cosmology with negative absolute temperatures

    NASA Astrophysics Data System (ADS)

    Vieira, J. P. P.; Byrnes, Christian T.; Lewis, Antony

    2016-08-01

    Negative absolute temperatures (NAT) are an exotic thermodynamical consequence of quantum physics which has been known since the 1950's (having been achieved in the lab on a number of occasions). Recently, the work of Braun et al. [1] has rekindled interest in negative temperatures and hinted at a possibility of using NAT systems in the lab as dark energy analogues. This paper goes one step further, looking into the cosmological consequences of the existence of a NAT component in the Universe. NAT-dominated expanding Universes experience a borderline phantom expansion (w < ‑1) with no Big Rip, and their contracting counterparts are forced to bounce after the energy density becomes sufficiently large. Both scenarios might be used to solve horizon and flatness problems analogously to standard inflation and bouncing cosmologies. We discuss the difficulties in obtaining and ending a NAT-dominated epoch, and possible ways of obtaining density perturbations with an acceptable spectrum.

  5. Factor Analysis with EM Algorithm Never Gives Improper Solutions when Sample Covariance and Initial Parameter Matrices Are Proper

    ERIC Educational Resources Information Center

    Adachi, Kohei

    2013-01-01

    Rubin and Thayer ("Psychometrika," 47:69-76, 1982) proposed the EM algorithm for exploratory and confirmatory maximum likelihood factor analysis. In this paper, we prove the following fact: the EM algorithm always gives a proper solution with positive unique variances and factor correlations with absolute values that do not exceed one, when the…

  6. Observations on the Proper Orthogonal Decomposition

    NASA Technical Reports Server (NTRS)

    Berkooz, Gal

    1992-01-01

    The Proper Orthogonal Decomposition (P.O.D.), also known as the Karhunen-Loeve expansion, is a procedure for decomposing a stochastic field in an L(2) optimal sense. It is used in diverse disciplines from image processing to turbulence. Recently the P.O.D. is receiving much attention as a tool for studying dynamics of systems in infinite dimensional space. This paper reviews the mathematical fundamentals of this theory. Also included are results on the span of the eigenfunction basis, a geometric corollary due to Chebyshev's inequality and a relation between the P.O.D. symmetry and ergodicity.

  7. Assigned value improves memory of proper names.

    PubMed

    Festini, Sara B; Hartley, Alan A; Tauber, Sarah K; Rhodes, Matthew G

    2013-01-01

    Names are more difficult to remember than other personal information such as occupations. The current research examined the influence of assigned point value on memory and metamemory judgements for names and occupations to determine whether incentive can improve recall of proper names. In Experiment 1 participants studied face-name and face-occupation pairs assigned 1 or 10 points, made judgements of learning, and were given a cued recall test. High-value names were recalled more often than low-value names. However, recall of occupations was not influenced by value. In Experiment 2 meaningless nonwords were used for both names and occupations. The name difficulty disappeared, and value influenced recall of both names and occupations. Thus value similarly influenced names and occupations when meaningfulness was held constant. In Experiment 3 participants were required to use overt rote rehearsal for all items. Value did not boost recall of high-value names, suggesting that differential processing could not be implemented to improve memory. Thus incentives may improve memory for proper names by motivating people to engage in selective rehearsal and effortful elaborative processing. PMID:23210532

  8. Proper horizontal photospheric flows in a filament channel

    NASA Astrophysics Data System (ADS)

    Schmieder, B.; Roudier, T.; Mein, N.; Mein, P.; Malherbe, J. M.; Chandra, R.

    2014-04-01

    Context. An extended filament in the central part of the active region NOAA 11106 crossed the central meridian on Sept. 17, 2010 in the southern hemisphere. It has been observed in Hα with the THEMIS telescope in the Canary Islands and in 304 Å with the EUV imager (AIA) onboard the Solar Dynamic Observatory (SDO). Counterstreaming along the Hα threads and bright moving blobs (jets) along the 304 Å filament channel were observed during 10 h before the filament erupted at 17:03 UT. Aims: The aim of the paper is to understand the coupling between magnetic field and convection in filament channels and relate the horizontal photospheric motions to the activity of the filament. Methods: An analysis of the proper photospheric motions using SDO/HMI continuum images with the new version of the coherent structure tracking (CST) algorithm developed to track granules, as well as the large scale photospheric flows, was performed for three hours. Using corks, we derived the passive scalar points and produced a map of the cork distribution in the filament channel. Averaging the velocity vectors in the southern hemisphere in each latitude in steps of 3.5 arcsec, we defined a profile of the differential rotation. Results: Supergranules are clearly identified in the filament channel. Diverging flows inside the supergranules are similar in and out of the filament channel. Converging flows corresponding to the accumulation of corks are identified well around the Hα filament feet and at the edges of the EUV filament channel. At these convergence points, the horizontal photospheric velocity may reach 1 km s-1, but with a mean velocity of 0.35 km s-1. In some locations, horizontal flows crossing the channel are detected, indicating eventually large scale vorticity. Conclusions: The coupling between convection and magnetic field in the photosphere is relatively strong. The filament experienced the convection motions through its anchorage points with the photosphere, which are

  9. Improving HST Pointing & Absolute Astrometry

    NASA Astrophysics Data System (ADS)

    Lallo, Matthew; Nelan, E.; Kimmer, E.; Cox, C.; Casertano, S.

    2007-05-01

    Accurate absolute astrometry is becoming increasingly important in an era of multi-mission archives and virtual observatories. Hubble Space Telescope's (HST's) Guidestar Catalog II (GSC2) has reduced coordinate error to around 0.25 arcsecond, a factor 2 or more compared with GSC1. With this reduced catalog error, special attention must be given to calibrate and maintain the Fine Guidance Sensors (FGSs) and Science Instruments (SIs) alignments in HST to a level well below this in order to ensure that the accuracy of science product's astrometry keywords and target positioning are limited only by the catalog errors. After HST Servicing Mission 4, such calibrations' improvement in "blind" pointing accuracy will allow for more efficient COS acquisitions. Multiple SIs and FGSs each have their own footprints in the spatially shared HST focal plane. It is the small changes over time in primarily the whole-body positions & orientations of these instruments & guiders relative to one another that is addressed by this work. We describe the HST Cycle 15 program CAL/OTA 11021 which, along with future variants of it, determines and maintains positions and orientations of the SIs and FGSs to better than 50 milli- arcseconds and 0.04 to 0.004 degrees of roll, putting errors associated with the alignment sufficiently below GSC2 errors. We present recent alignment results and assess their errors, illustrate trends, and describe where and how the observer sees benefit from these calibrations when using HST.

  10. Absolute oral bioavailability of ciprofloxacin.

    PubMed

    Drusano, G L; Standiford, H C; Plaisance, K; Forrest, A; Leslie, J; Caldwell, J

    1986-09-01

    We evaluated the absolute bioavailability of ciprofloxacin, a new quinoline carboxylic acid, in 12 healthy male volunteers. Doses of 200 mg were given to each of the volunteers in a randomized, crossover manner 1 week apart orally and as a 10-min intravenous infusion. Half-lives (mean +/- standard deviation) for the intravenous and oral administration arms were 4.2 +/- 0.77 and 4.11 +/- 0.74 h, respectively. The serum clearance rate averaged 28.5 +/- 4.7 liters/h per 1.73 m2 for the intravenous administration arm. The renal clearance rate accounted for approximately 60% of the corresponding serum clearance rate and was 16.9 +/- 3.0 liters/h per 1.73 m2 for the intravenous arm and 17.0 +/- 2.86 liters/h per 1.73 m2 for the oral administration arm. Absorption was rapid, with peak concentrations in serum occurring at 0.71 +/- 0.15 h. Bioavailability, defined as the ratio of the area under the curve from 0 h to infinity for the oral to the intravenous dose, was 69 +/- 7%. We conclude that ciprofloxacin is rapidly absorbed and reliably bioavailable in these healthy volunteers. Further studies with ciprofloxacin should be undertaken in target patient populations under actual clinical circumstances. PMID:3777908

  11. Absolute Instability in Coupled-Cavity TWTs

    NASA Astrophysics Data System (ADS)

    Hung, D. M. H.; Rittersdorf, I. M.; Zhang, Peng; Lau, Y. Y.; Simon, D. H.; Gilgenbach, R. M.; Chernin, D.; Antonsen, T. M., Jr.

    2014-10-01

    This paper will present results of our analysis of absolute instability in a coupled-cavity traveling wave tube (TWT). The structure mode at the lower and upper band edges are respectively approximated by a hyperbola in the (omega, k) plane. When the Briggs-Bers criterion is applied, a threshold current for onset of absolute instability is observed at the upper band edge, but not the lower band edge. The nonexistence of absolute instability at the lower band edge is mathematically similar to the nonexistence of absolute instability that we recently demonstrated for a dielectric TWT. The existence of absolute instability at the upper band edge is mathematically similar to the existence of absolute instability in a gyroton traveling wave amplifier. These interesting observations will be discussed, and the practical implications will be explored. This work was supported by AFOSR, ONR, and L-3 Communications Electron Devices.

  12. Absolute negative mobility of interacting Brownian particles

    NASA Astrophysics Data System (ADS)

    Ou, Ya-li; Hu, Cai-tian; Wu, Jian-chun; Ai, Bao-quan

    2015-12-01

    Transport of interacting Brownian particles in a periodic potential is investigated in the presence of an ac force and a dc force. From Brownian dynamic simulations, we find that both the interaction between particles and the thermal fluctuations play key roles in the absolute negative mobility (the particle noisily moves backwards against a small constant bias). When no the interaction acts, there is only one region where the absolute negative mobility occurs. In the presence of the interaction, the absolute negative mobility may appear in multiple regions. The weak interaction can be helpful for the absolute negative mobility, while the strong interaction has a destructive impact on it.

  13. Swirl technology: Proper design, application, and evaluation

    SciTech Connect

    Field, R.; O`Connor, T.P.

    1995-10-01

    Swirl and vortex technologies have been with us for over thirty years now, ever since Bernard Smisson incorporated a cylindrical vortex-type combined sewer overflow (CSO) regulator/settleable-solids concentrator into the Bristol, England sewerage system back in the early 1960`s. In the early 1970`s the U.S. Environmental Protection Agency (EPA) conducted a series of projects to develop and demonstrate swirl flow regulator/settleable-solids concentrator (swirl) technology. These projects resulted in the EPA swirl and helical-bend flow regulators/settleable-solids concentrators and the swirl degritter. New generations of this technology emerged after the EPA versions were developed including the Fluidsep{trademark} and the Storm King{trademark} vortex-hydrodynamic separators. However, despite different designs and applications, the main intent of the technologies are the same, i.e., to use the forces that arise from a change in flow direction to enhance settleable-solids separation from the storm flow. A variety of opinions have developed regarding the application of these technologies varying from overwhelming support to detractions that question their effectiveness. This abstract will show that proper design and placement in the sewerage system results in effective use of swirl technology. Reliable swirl pollution control efficiency determination is principally dependent on proper sampling and suspended and settleable-solids analysis techniques of the influent and effluent. Simultaneous flowrate measurement is also important. Without the complete capture of heavy and stratified suspended solids (SS) across the influent flow channel or water column, the apparent performance of the swirl will be less than the actual. Particle-settleability tests which are presented, must be conducted before and after installation, but especially before in order to decide if the inertial characteristics of SS in the storm flow warrants the use of a swirl.

  14. Circular motion

    NASA Astrophysics Data System (ADS)

    Newton, Isaac; Henry, Richard Conn

    2000-07-01

    An extraordinarily simple and transparent derivation of the formula for the acceleration that occurs in uniform circular motion is presented, and is advocated for use in high school and college freshman physics textbooks.

  15. Polar motion

    NASA Technical Reports Server (NTRS)

    Kolenkiewicz, R.

    1973-01-01

    Tracking of the Beacon Explorer-C satellite by a precision laser system was used to measure the polar motion and solid earth tide. The tidal perturbation of satellite latitude is plotted as variation in maximum latitude in seconds of arc on earth's surface as a function of the date, and polar motion is shown by plotting the variation in latitude of the laser in seconds of arc along the earth's surface as a function of date

  16. Inequalities, Absolute Value, and Logical Connectives.

    ERIC Educational Resources Information Center

    Parish, Charles R.

    1992-01-01

    Presents an approach to the concept of absolute value that alleviates students' problems with the traditional definition and the use of logical connectives in solving related problems. Uses a model that maps numbers from a horizontal number line to a vertical ray originating from the origin. Provides examples solving absolute value equations and…

  17. Absolute optical metrology : nanometers to kilometers

    NASA Technical Reports Server (NTRS)

    Dubovitsky, Serge; Lay, O. P.; Peters, R. D.; Liebe, C. C.

    2005-01-01

    We provide and overview of the developments in the field of high-accuracy absolute optical metrology with emphasis on space-based applications. Specific work on the Modulation Sideband Technology for Absolute Ranging (MSTAR) sensor is described along with novel applications of the sensor.

  18. Monolithically integrated absolute frequency comb laser system

    DOEpatents

    Wanke, Michael C.

    2016-07-12

    Rather than down-convert optical frequencies, a QCL laser system directly generates a THz frequency comb in a compact monolithically integrated chip that can be locked to an absolute frequency without the need of a frequency-comb synthesizer. The monolithic, absolute frequency comb can provide a THz frequency reference and tool for high-resolution broad band spectroscopy.

  19. Introducing the Mean Absolute Deviation "Effect" Size

    ERIC Educational Resources Information Center

    Gorard, Stephen

    2015-01-01

    This paper revisits the use of effect sizes in the analysis of experimental and similar results, and reminds readers of the relative advantages of the mean absolute deviation as a measure of variation, as opposed to the more complex standard deviation. The mean absolute deviation is easier to use and understand, and more tolerant of extreme…

  20. Investigating Absolute Value: A Real World Application

    ERIC Educational Resources Information Center

    Kidd, Margaret; Pagni, David

    2009-01-01

    Making connections between various representations is important in mathematics. In this article, the authors discuss the numeric, algebraic, and graphical representations of sums of absolute values of linear functions. The initial explanations are accessible to all students who have experience graphing and who understand that absolute value simply…

  1. Absolute Income, Relative Income, and Happiness

    ERIC Educational Resources Information Center

    Ball, Richard; Chernova, Kateryna

    2008-01-01

    This paper uses data from the World Values Survey to investigate how an individual's self-reported happiness is related to (i) the level of her income in absolute terms, and (ii) the level of her income relative to other people in her country. The main findings are that (i) both absolute and relative income are positively and significantly…

  2. Absolute instability of the Gaussian wake profile

    NASA Technical Reports Server (NTRS)

    Hultgren, Lennart S.; Aggarwal, Arun K.

    1987-01-01

    Linear parallel-flow stability theory has been used to investigate the effect of viscosity on the local absolute instability of a family of wake profiles with a Gaussian velocity distribution. The type of local instability, i.e., convective or absolute, is determined by the location of a branch-point singularity with zero group velocity of the complex dispersion relation for the instability waves. The effects of viscosity were found to be weak for values of the wake Reynolds number, based on the center-line velocity defect and the wake half-width, larger than about 400. Absolute instability occurs only for sufficiently large values of the center-line wake defect. The critical value of this parameter increases with decreasing wake Reynolds number, thereby indicating a shrinking region of absolute instability with decreasing wake Reynolds number. If backflow is not allowed, absolute instability does not occur for wake Reynolds numbers smaller than about 38.

  3. Asteroid Motions

    NASA Astrophysics Data System (ADS)

    Sykes, Mary V.; Moynihan, P. Daniel

    1996-12-01

    Equations are derived which describe the apparent motion of an asteroid traveling on an elliptical orbit in geocentric ecliptic coordinates. At opposition, the equations are identical to those derived by Bowellet al. (Bowell, E., B. Skiff, and L. Wasserman 1990. InAsteroids, Comets, Meteors III(C.-I. Lagerkvist, M. Rickman, B. A. Lindblad, and M. Lindgren, Eds.), pp. 19-24. Uppsala Universitet, Uppsala, Sweden). These equations can be an important component in the optimization of search strategies for specific asteroid populations based on their apparent motions relative to other populations when observed away from opposition.

  4. Ocean Models and Proper Orthogonal Decomposition

    NASA Astrophysics Data System (ADS)

    Salas-de-Leon, D. A.

    2007-05-01

    The increasing computational developments and the better understanding of mathematical and physical systems resulted in an increasing number of ocean models. Long time ago, modelers were like a secret organization and recognize each other by using secret codes and languages that only a select group of people was able to recognize and understand. The access to computational systems was reduced, on one hand equipment and the using time of computers were expensive and restricted, and on the other hand, they required an advance computational languages that not everybody wanted to learn. Now a days most college freshman own a personal computer (PC or laptop), and/or have access to more sophisticated computational systems than those available for research in the early 80's. The resource availability resulted in a mayor access to all kind models. Today computer speed and time and the algorithms does not seem to be a problem, even though some models take days to run in small computational systems. Almost every oceanographic institution has their own model, what is more, in the same institution from one office to the next there are different models for the same phenomena, developed by different research member, the results does not differ substantially since the equations are the same, and the solving algorithms are similar. The algorithms and the grids, constructed with algorithms, can be found in text books and/or over the internet. Every year more sophisticated models are constructed. The Proper Orthogonal Decomposition is a technique that allows the reduction of the number of variables to solve keeping the model properties, for which it can be a very useful tool in diminishing the processes that have to be solved using "small" computational systems, making sophisticated models available for a greater community.

  5. Absolute Entropy and Energy of Carbon Dioxide Using the Two-Phase Thermodynamic Model.

    PubMed

    Huang, Shao-Nung; Pascal, Tod A; Goddard, William A; Maiti, Prabal K; Lin, Shiang-Tai

    2011-06-14

    The two-phase thermodynamic (2PT) model is used to determine the absolute entropy and energy of carbon dioxide over a wide range of conditions from molecular dynamics trajectories. The 2PT method determines the thermodynamic properties by applying the proper statistical mechanical partition function to the normal modes of a fluid. The vibrational density of state (DoS), obtained from the Fourier transform of the velocity autocorrelation function, converges quickly, allowing the free energy, entropy, and other thermodynamic properties to be determined from short 20-ps MD trajectories. The anharmonic effects in the vibrations are accounted for by the broadening of the normal modes into bands from sampling the velocities over the trajectory. The low frequency diffusive modes, which lead to finite DoS at zero frequency, are accounted for by considering the DoS as a superposition of gas-phase and solid-phase components (two phases). The analytical decomposition of the DoS allows for an evaluation of properties contributed by different types of molecular motions. We show that this 2PT analysis leads to accurate predictions of entropy and energy of CO2 over a wide range of conditions (from the triple point to the critical point of both the vapor and the liquid phases along the saturation line). This allows the equation of state of CO2 to be determined, which is limited only by the accuracy of the force field. We also validated that the 2PT entropy agrees with that determined from thermodynamic integration, but 2PT requires only a fraction of the time. A complication for CO2 is that its equilibrium configuration is linear, which would have only two rotational modes, but during the dynamics it is never exactly linear, so that there is a third mode from rotational about the axis. In this work, we show how to treat such linear molecules in the 2PT framework. PMID:26596450

  6. What's Motion Sickness?

    MedlinePlus

    ... Homework? Here's Help White House Lunch Recipes What's Motion Sickness? KidsHealth > For Kids > What's Motion Sickness? Print ... motion sickness might get even worse. continue Avoiding Motion Sickness To avoid motion sickness: Put your best ...

  7. Absolute optical instruments without spherical symmetry

    NASA Astrophysics Data System (ADS)

    Tyc, Tomáš; Dao, H. L.; Danner, Aaron J.

    2015-11-01

    Until now, the known set of absolute optical instruments has been limited to those containing high levels of symmetry. Here, we demonstrate a method of mathematically constructing refractive index profiles that result in asymmetric absolute optical instruments. The method is based on the analogy between geometrical optics and classical mechanics and employs Lagrangians that separate in Cartesian coordinates. In addition, our method can be used to construct the index profiles of most previously known absolute optical instruments, as well as infinitely many different ones.

  8. Brownian Motion.

    ERIC Educational Resources Information Center

    Lavenda, Bernard H.

    1985-01-01

    Explains the phenomenon of Brownian motion, which serves as a mathematical model for random processes. Topics addressed include kinetic theory, Einstein's theory, particle displacement, and others. Points out that observations of the random course of a particle suspended in fluid led to the first accurate measurement of atomic mass. (DH)

  9. Choice of the proper wavelength for photochemotherapy

    NASA Astrophysics Data System (ADS)

    Moan, Johan; Iani, Vladimir; Ma, LiWei

    1996-01-01

    All photosensitizers applied in experimental- and clinical-photochemotherapy (PCT) have broad absorption spectra stretching from the ultraviolet up to 6 - 700 nm. Light of wavelengths in the red part of the spectrum is chosen for PCT even though the extinction coefficients of the sensitizers are usually smaller in this wavelength region than at shorter wavelengths. Thus, if one wants to treat superficial tumors or skin disorders, this may be a wrong choice. Two pieces of information are needed in order to make a proper choice of wavelength to treat a lesion of a given depth: the wavelength dependence of the optical penetration depth into tissue, and the action spectrum for tumor destruction. Additionally, the skin photosensitivity induced by the drug should be considered. We have non-invasively measured the optical penetration spectra of human tissues in vivo and the fluorescence excitation spectra for several sensitizers, including protoporphyrin (PpIX), in cells. Assuming that the action spectrum for cell inactivation can be approximated by the fluorescence excitation spectrum of the sensitizer -- which is indeed the case for a number of sensitizers in cells in vitro -- we have considered the situation for 5-aminolevulinic acid-induced PpIX in human tissue. All the way down to about 2 mm below the surface light in the Soret band (-410 nm) would give the largest cell inactivation, while at depth exceeding 2 mm, the conventional 635 nm light would be optimal. Light at the argon laser wavelength 514.5 nm is more efficient than light at 635 nm down to 1 mm. From the surface and down to 6 mm, the 635 nm peak of the excitation spectrum of PpIX, as evaluated per photon incident on the skin surface, is redshifted by less than 2 nm. In some cases photosensitizing photoproducts are formed during PCT, such as photoprotoporphyrin during PCT with PpIX. In such cases it may be advantageous to apply a broad-band light source with a spectrum that covers also part of the action

  10. VizieR Online Data Catalog: Proper motion and BV photometry in Trumpler 2 (Frolov+, 2006)

    NASA Astrophysics Data System (ADS)

    Frolov, V. N.; Ananjevskaja, J. K.; Jilinski, E. G.; Gorshanov, D. L.; Bronnikova, N. M.

    2006-05-01

    All of the plates were scanned by means of the automated measuring complex "Fantasy" of the Pulkovo observatory. The description of the complex was presented in Frolov et al. (2002, Cat. ). (4 data files).

  11. VizieR Online Data Catalog: OGLE-III. Magellanic Clouds stellar proper motions (Poleski+, 2012)

    NASA Astrophysics Data System (ADS)

    Poleski, R.; Soszynski, I.; Udalski, A.; Szymanski, M. K.; Kubiak, M.; Pietrzynski, G.; Wyrzykowski, L.; Ulaczyk, K.

    2015-07-01

    The OGLE-III project observed the Large Magellanic Cloud, the Small Magellanic Cloud, and the globular cluster 47 Tuc between 2001 and 2009 with the 1.3-m Warsaw telescope, which is situated at the Las Campanas Observatory, Chile. The telescope was equipped with an eight-chip mosaic CCD camera. The field of view was 36'x36' and the pixel scale was 0.26"/pix. I-band filter was used. (5 data files).

  12. VizieR Online Data Catalog: NIR proper motion catalogue from UKIDSS-LAS (Smith+, 2014)

    NASA Astrophysics Data System (ADS)

    Smith, L.; Lucas, P. W.; Burningham, B.; Jones, H. R. A.; Smart, R. L.; Andrei, A. H.; Catalan, S.; Pinfield, D. J.

    2015-07-01

    We constructed two epoch catalogues for each pointing by matching sources within the pairs of multiframes using the Starlink Tables Infrastructure Library Tool Set (STILTS; Taylor 2006, ASP conf. Ser. 351, 666). We required pairs of sources to be uniquely paired to their closest match within 6-arcsec, and we required the J band magnitudes for the two epochs to agree within 0.5mag, to minimize mismatches. (1 data file).

  13. VizieR Online Data Catalog: Proper motions in 6 globular clusters (Zloczewski+, 2012)

    NASA Astrophysics Data System (ADS)

    Zloczewski, K.; Kaluzny, J.; Rozyczka, M.; Krzeminski, W.; Mazur, B.; Thompson, I. B.

    2013-02-01

    The images analyzed in this paper are a part of the data collected between 1997 and 2008 within the CASE project (Cluster AgeS Experiment). All observations were made with the 2.5-m du Pont telescope at LCO using the same detector and the same set of V and I filters. (7 data files).

  14. VLBI limits on the proper motion of the 'core' of the superluminal quasar 3C345

    NASA Technical Reports Server (NTRS)

    Bartel, N.; Herring, T. A.; Ratner, M. I.; Shapiro, I. I.; Corey, B. E.

    1986-01-01

    VLBI (very-long-baseline interferometry) observations between 1971 and 1983 have been used to determine the positions of the 'core' of the quasar 3C345 relative to the more distant compact quasar NRAO512 with a fractional uncertainty as small as two parts in a hundred million. The core of 3C345 appears stationary in right ascension to within 20 arc microsec/yr, a subluminal bound corresponding to 0.7c. The apparent velocities of the jets are superluminal, up to 14c in magnitude.

  15. Absolute magnitudes of trans-neptunian objects

    NASA Astrophysics Data System (ADS)

    Duffard, R.; Alvarez-candal, A.; Pinilla-Alonso, N.; Ortiz, J. L.; Morales, N.; Santos-Sanz, P.; Thirouin, A.

    2015-10-01

    Accurate measurements of diameters of trans- Neptunian objects are extremely complicated to obtain. Radiomatric techniques applied to thermal measurements can provide good results, but precise absolute magnitudes are needed to constrain diameters and albedos. Our objective is to measure accurate absolute magnitudes for a sample of trans- Neptunian objects, many of which have been observed, and modelled, by the "TNOs are cool" team, one of Herschel Space Observatory key projects grantes with ~ 400 hours of observing time. We observed 56 objects in filters V and R, if possible. These data, along with data available in the literature, was used to obtain phase curves and to measure absolute magnitudes by assuming a linear trend of the phase curves and considering magnitude variability due to rotational light-curve. In total we obtained 234 new magnitudes for the 56 objects, 6 of them with no reported previous measurements. Including the data from the literature we report a total of 109 absolute magnitudes.

  16. A New Gimmick for Assigning Absolute Configuration.

    ERIC Educational Resources Information Center

    Ayorinde, F. O.

    1983-01-01

    A five-step procedure is provided to help students in making the assignment absolute configuration less bothersome. Examples for both single (2-butanol) and multi-chiral carbon (3-chloro-2-butanol) molecules are included. (JN)

  17. Absolute properties of the eclipsing binary star IM Persei

    SciTech Connect

    Lacy, Claud H. Sandberg; Torres, Guillermo; Fekel, Francis C.; Muterspaugh, Matthew W.; Southworth, John E-mail: gtorres@cfa.harvard.edu E-mail: matthew1@coe.tsuniv.edu

    2015-01-01

    IM Per is a detached A7 eccentric eclipsing binary star. We have obtained extensive measurements of the light curve (28,225 differential magnitude observations) and radial velocity curve (81 spectroscopic observations) which allow us to fit orbits and determine the absolute properties of the components very accurately: masses of 1.7831 ± 0.0094 and 1.7741 ± 0.0097 solar masses, and radii of 2.409 ± 0.018 and 2.366 ± 0.017 solar radii. The orbital period is 2.25422694(15) days and the eccentricity is 0.0473(26). A faint third component was detected in the analysis of the light curves, and also directly observed in the spectra. The observed rate of apsidal motion is consistent with theory (U = 151.4 ± 8.4 year). We determine a distance to the system of 566 ± 46 pc.

  18. Absolute and relative choreographies in rigid body dynamics

    NASA Astrophysics Data System (ADS)

    Borisov, A. V.; Kilin, A. A.; Mamaev, I. S.

    2008-06-01

    For the classical problem of motion of a rigid body about a fixed point with zero area integral, we present a family of solutions that are periodic in the absolute space. Such solutions are known as choreographies. The family includes the well-known Delone solutions (for the Kovalevskaya case), some particular solutions for the Goryachev-Chaplygin case, and the Steklov solution. The “genealogy” of solutions of the family naturally appearing from the energy continuation and their connection with the Staude rotations are considered. It is shown that if the integral of areas is zero, the solutions are periodic with respect to a coordinate frame that rotates uniformly about the vertical (relative choreographies).

  19. Absolute negative mobility induced by potential phase modulation

    NASA Astrophysics Data System (ADS)

    Dandogbessi, Bruno S.; Kenfack, Anatole

    2015-12-01

    We investigate the transport properties of a particle subjected to a deterministic inertial rocking system, under a constant bias, for which the phase of the symmetric spatial potential used is time modulated. We show that this modulated phase, assisted by a periodic driving force, can lead to the occurrence of the so-called absolute negative mobility (ANM), the phenomenon in which the particle surprisingly moves against the bias. Furthermore, we discover that ANM predominantly originates from chaotic-periodic transitions. While a detailed mechanism of ANM remains unclear, we show that one can manipulate the control parameters, i.e., the amplitude and the frequency of the phase, in order to enforce the motion of the particle in a given direction. Finally, for this experimentally realizable system, we devise a two-parameter current plot which may be a good guide for controlling ANM.

  20. Jasminum flexile flower absolute from India--a detailed comparison with three other jasmine absolutes.

    PubMed

    Braun, Norbert A; Kohlenberg, Birgit; Sim, Sherina; Meier, Manfred; Hammerschmidt, Franz-Josef

    2009-09-01

    Jasminum flexile flower absolute from the south of India and the corresponding vacuum headspace (VHS) sample of the absolute were analyzed using GC and GC-MS. Three other commercially available Indian jasmine absolutes from the species: J. sambac, J. officinale subsp. grandiflorum, and J. auriculatum and the respective VHS samples were used for comparison purposes. One hundred and twenty-one compounds were characterized in J. flexile flower absolute, with methyl linolate, benzyl salicylate, benzyl benzoate, (2E,6E)-farnesol, and benzyl acetate as the main constituents. A detailed olfactory evaluation was also performed. PMID:19831037

  1. Construction of Lagrangians and Hamiltonians from the Equation of Motion

    ERIC Educational Resources Information Center

    Yan, C. C.

    1978-01-01

    Demonstrates that infinitely many Lagrangians and Hamiltonians can be constructed from a given equation of motion. Points out the lack of an established criterion for making a proper selection. (Author/GA)

  2. The Case for Absolute Ligand Discrimination: Modeling Information Processing and Decision by Immune T Cells

    NASA Astrophysics Data System (ADS)

    François, Paul; Altan-Bonnet, Grégoire

    2016-03-01

    Some cells have to take decision based on the quality of surroundings ligands, almost irrespective of their quantity, a problem we name "absolute discrimination". An example of absolute discrimination is recognition of not-self by immune T Cells. We show how the problem of absolute discrimination can be solved by a process called "adaptive sorting". We review several implementations of adaptive sorting, as well as its generic properties such as antagonism. We show how kinetic proofreading with negative feedback implement an approximate version of adaptive sorting in the immune context. Finally, we revisit the decision problem at the cell population level, showing how phenotypic variability and feedbacks between population and single cells are crucial for proper decision.

  3. Thorough subcells diagnosis in a multi-junction solar cell via absolute electroluminescence-efficiency measurements.

    PubMed

    Chen, Shaoqiang; Zhu, Lin; Yoshita, Masahiro; Mochizuki, Toshimitsu; Kim, Changsu; Akiyama, Hidefumi; Imaizumi, Mitsuru; Kanemitsu, Yoshihiko

    2015-01-01

    World-wide studies on multi-junction (tandem) solar cells have led to record-breaking improvements in conversion efficiencies year after year. To obtain detailed and proper feedback for solar-cell design and fabrication, it is necessary to establish standard methods for diagnosing subcells in fabricated tandem devices. Here, we propose a potential standard method to quantify the detailed subcell properties of multi-junction solar cells based on absolute measurements of electroluminescence (EL) external quantum efficiency in addition to the conventional solar-cell external-quantum-efficiency measurements. We demonstrate that the absolute-EL-quantum-efficiency measurements provide I-V relations of individual subcells without the need for referencing measured I-V data, which is in stark contrast to previous works. Moreover, our measurements quantify the absolute rates of junction loss, non-radiative loss, radiative loss, and luminescence coupling in the subcells, which constitute the "balance sheets" of tandem solar cells. PMID:25592484

  4. Universal Cosmic Absolute and Modern Science

    NASA Astrophysics Data System (ADS)

    Kostro, Ludwik

    The official Sciences, especially all natural sciences, respect in their researches the principle of methodic naturalism i.e. they consider all phenomena as entirely natural and therefore in their scientific explanations they do never adduce or cite supernatural entities and forces. The purpose of this paper is to show that Modern Science has its own self-existent, self-acting, and self-sufficient Natural All-in Being or Omni-Being i.e. the entire Nature as a Whole that justifies the scientific methodic naturalism. Since this Natural All-in Being is one and only It should be considered as the own scientifically justified Natural Absolute of Science and should be called, in my opinion, the Universal Cosmic Absolute of Modern Science. It will be also shown that the Universal Cosmic Absolute is ontologically enormously stratified and is in its ultimate i.e. in its most fundamental stratum trans-reistic and trans-personal. It means that in its basic stratum. It is neither a Thing or a Person although It contains in Itself all things and persons with all other sentient and conscious individuals as well, On the turn of the 20th century the Science has begun to look for a theory of everything, for a final theory, for a master theory. In my opinion the natural Universal Cosmic Absolute will constitute in such a theory the radical all penetrating Ultimate Basic Reality and will substitute step by step the traditional supernatural personal Absolute.

  5. Proper orthogonal decomposition method for analysis of nonlinear panel flutter with thermal effects in supersonic flow

    NASA Astrophysics Data System (ADS)

    Xie, Dan; Xu, Min; Dai, Honghua; Dowell, Earl H.

    2015-02-01

    The proper orthogonal decomposition (POD) method for analysis of nonlinear panel flutter subjected to supersonic flow is presented. Optimal POD modes are extracted from a chaotic Galerkin mode responses. The aeroelastic equations of motion are constructed using von Karman plate theory, first-order piston theory and quasi-steady thermal stress theory. A simply-supported plate with thermal loads from a uniformly distributed temperature is considered. Many types of panel behaviors, including stable flat, dynamically stable buckled, limit cycle oscillation, nonharmonic periodic motion, quasi-periodic motion and chaotic motion are observed. Our primary focus is on chaos and the route to chaos. It is found that a sudden transition from the buckled state to chaos occurs. Time history, phase portrait, Poincaré map, bifurcation diagram and Lyapunov exponent are employed to study chaos. The POD chaotic results obtained are compared with the traditional Galerkin solutions. It is shown that the POD method can obtain accurate chaotic solutions, using fewer modes and less computational effort than the Galerkin mode approach; additionally, the POD method converges faster in the analysis of chaotic transients. Effects of length-to-width ratios and thermal loads are presented. It is found that a smaller width for fixed length will produce more stable flutter response, while the thermal loads degrade the flutter boundary and result in a more complex evolution of dynamic motions. The numerical simulations show that the robustness of the POD modes depends on the dynamic pressure but not on temperature.

  6. GAIA: A WINDOW TO LARGE-SCALE MOTIONS

    SciTech Connect

    Nusser, Adi; Branchini, Enzo; Davis, Marc E-mail: branchin@fis.uniroma3.it

    2012-08-10

    Using redshifts as a proxy for galaxy distances, estimates of the two-dimensional (2D) transverse peculiar velocities of distant galaxies could be obtained from future measurements of proper motions. We provide the mathematical framework for analyzing 2D transverse motions and show that they offer several advantages over traditional probes of large-scale motions. They are completely independent of any intrinsic relations between galaxy properties; hence, they are essentially free of selection biases. They are free from homogeneous and inhomogeneous Malmquist biases that typically plague distance indicator catalogs. They provide additional information to traditional probes that yield line-of-sight peculiar velocities only. Further, because of their 2D nature, fundamental questions regarding vorticity of large-scale flows can be addressed. Gaia, for example, is expected to provide proper motions of at least bright galaxies with high central surface brightness, making proper motions a likely contender for traditional probes based on current and future distance indicator measurements.

  7. Absolute isotopic abundances of TI in meteorites

    NASA Astrophysics Data System (ADS)

    Niederer, F. R.; Papanastassiou, D. A.; Wasserburg, G. J.

    1985-03-01

    The absolute isotope abundance of Ti has been determined in Ca-Al-rich inclusions from the Allende and Leoville meteorites and in samples of whole meteorites. The absolute Ti isotope abundances differ by a significant mass dependent isotope fractionation transformation from the previously reported abundances, which were normalized for fractionation using 46Ti/48Ti. Therefore, the absolute compositions define distinct nucleosynthetic components from those previously identified or reflect the existence of significant mass dependent isotope fractionation in nature. The authors provide a general formalism for determining the possible isotope compositions of the exotic Ti from the measured composition, for different values of isotope fractionation in nature and for different mixing ratios of the exotic and normal components.

  8. Molecular iodine absolute frequencies. Final report

    SciTech Connect

    Sansonetti, C.J.

    1990-06-25

    Fifty specified lines of {sup 127}I{sub 2} were studied by Doppler-free frequency modulation spectroscopy. For each line the classification of the molecular transition was determined, hyperfine components were identified, and one well-resolved component was selected for precise determination of its absolute frequency. In 3 cases, a nearby alternate line was selected for measurement because no well-resolved component was found for the specified line. Absolute frequency determinations were made with an estimated uncertainty of 1.1 MHz by locking a dye laser to the selected hyperfine component and measuring its wave number with a high-precision Fabry-Perot wavemeter. For each line results of the absolute measurement, the line classification, and a Doppler-free spectrum are given.

  9. Stimulus probability effects in absolute identification.

    PubMed

    Kent, Christopher; Lamberts, Koen

    2016-05-01

    This study investigated the effect of stimulus presentation probability on accuracy and response times in an absolute identification task. Three schedules of presentation were used to investigate the interaction between presentation probability and stimulus position within the set. Data from individual participants indicated strong effects of presentation probability on both proportion correct and response times. The effects were moderated by the ubiquitous stimulus position effect. The accuracy and response time data were predicted by an exemplar-based model of perceptual cognition (Kent & Lamberts, 2005). The bow in discriminability was also attenuated when presentation probability for middle items was relatively high, an effect that will constrain future model development. The study provides evidence for item-specific learning in absolute identification. Implications for other theories of absolute identification are discussed. (PsycINFO Database Record PMID:26478959

  10. Absolute calibration in vivo measurement systems

    SciTech Connect

    Kruchten, D.A.; Hickman, D.P.

    1991-02-01

    Lawrence Livermore National Laboratory (LLNL) is currently investigating a new method for obtaining absolute calibration factors for radiation measurement systems used to measure internally deposited radionuclides in vivo. Absolute calibration of in vivo measurement systems will eliminate the need to generate a series of human surrogate structures (i.e., phantoms) for calibrating in vivo measurement systems. The absolute calibration of in vivo measurement systems utilizes magnetic resonance imaging (MRI) to define physiological structure, size, and composition. The MRI image provides a digitized representation of the physiological structure, which allows for any mathematical distribution of radionuclides within the body. Using Monte Carlo transport codes, the emission spectrum from the body is predicted. The in vivo measurement equipment is calibrated using the Monte Carlo code and adjusting for the intrinsic properties of the detection system. The calibration factors are verified using measurements of existing phantoms and previously obtained measurements of human volunteers. 8 refs.

  11. Absolute Gravimetry in Fennoscandia - A Contribution to Understanding Postglacial Uplift

    NASA Astrophysics Data System (ADS)

    Pettersen, B. R.; Timmen, L.; Gitlein, O.; Muller, J.; Denker, H.; Makinen, J.; Bilker, M.; Lysaker, D. I.; Omang, O. C.; Svendsen, J. G.; Wilmes, H.; Falk, R.; Reinhold, A.; Hoppe, W.; Scherneck, H.; Lidberg, M.; Engen, B.; Kristiansen, O.; Engfeldt, A.; Strykowski, G.; Forsberg, R.; Klopping, F.; Sasagawa, G.

    2005-12-01

    The Fennoscandian postglacial uplift has been mapped geometrically using precise levelling, tide gauges, and networks of permanent GPS stations. The results identify major uplift rates at sites located around the northern part of the Gulf of Bothnia. The vertical motions decay in all directions away from this central location. An oval shaped zero uplift isoline tracks the general western and northern coastline of Norway and the Kola peninsula. It returns southwest through Russian Karelia and touches the southern tip of Sweden and northern Denmark. The uplift area (as measured by present day motions) has its major axis in the direction of southwest to northeast and covers a distance of about 2000 km. Absolute gravimetry was made in Finland and Norway in 1976 with a rise-and fall instrument. A decade later the number of gravity stations was expanded by JILAg-5, in Finland from 1988, in Norway from 1991, and in Sweden from 1992. FG5 was introduced in these three countries in 1993 (7 stations) and continued with an extended campaign in 1995 (12 stations). In 2003 a project was initiated by IfE, Hannover to collect observations simultaneously with GRACE on an annual cycle. New instruments were acquired by IfE (FG5-220), FGI (FG5-221), and UMB (FG5-226). New absolute gravity stations were established by the national mapping agencies in Denmark, Norway, and Sweden. The total number of prepared sites in Fennoscandia is now about 30. Most of them are co-located with permanent GPS, for many of which time series of several years are now available. Along the coast there are nearby tide gauge stations, many of which have time series of several decades. We describe the observing network, procedures, auxiliary observations, and discuss results obtained for selected sites. We compare the gravity results from different instruments and discuss the challenges of combining and validating such data products. Examples are shown where temporal gravity change may be compared to

  12. Precise Measurement of the Absolute Fluorescence Yield

    NASA Astrophysics Data System (ADS)

    Ave, M.; Bohacova, M.; Daumiller, K.; Di Carlo, P.; di Giulio, C.; San Luis, P. Facal; Gonzales, D.; Hojvat, C.; Hörandel, J. R.; Hrabovsky, M.; Iarlori, M.; Keilhauer, B.; Klages, H.; Kleifges, M.; Kuehn, F.; Monasor, M.; Nozka, L.; Palatka, M.; Petrera, S.; Privitera, P.; Ridky, J.; Rizi, V.; D'Orfeuil, B. Rouille; Salamida, F.; Schovanek, P.; Smida, R.; Spinka, H.; Ulrich, A.; Verzi, V.; Williams, C.

    2011-09-01

    We present preliminary results of the absolute yield of fluorescence emission in atmospheric gases. Measurements were performed at the Fermilab Test Beam Facility with a variety of beam particles and gases. Absolute calibration of the fluorescence yield to 5% level was achieved by comparison with two known light sources--the Cherenkov light emitted by the beam particles, and a calibrated nitrogen laser. The uncertainty of the energy scale of current Ultra-High Energy Cosmic Rays experiments will be significantly improved by the AIRFLY measurement.

  13. Absolutely relative or relatively absolute: violations of value invariance in human decision making.

    PubMed

    Teodorescu, Andrei R; Moran, Rani; Usher, Marius

    2016-02-01

    Making decisions based on relative rather than absolute information processing is tied to choice optimality via the accumulation of evidence differences and to canonical neural processing via accumulation of evidence ratios. These theoretical frameworks predict invariance of decision latencies to absolute intensities that maintain differences and ratios, respectively. While information about the absolute values of the choice alternatives is not necessary for choosing the best alternative, it may nevertheless hold valuable information about the context of the decision. To test the sensitivity of human decision making to absolute values, we manipulated the intensities of brightness stimuli pairs while preserving either their differences or their ratios. Although asked to choose the brighter alternative relative to the other, participants responded faster to higher absolute values. Thus, our results provide empirical evidence for human sensitivity to task irrelevant absolute values indicating a hard-wired mechanism that precedes executive control. Computational investigations of several modelling architectures reveal two alternative accounts for this phenomenon, which combine absolute and relative processing. One account involves accumulation of differences with activation dependent processing noise and the other emerges from accumulation of absolute values subject to the temporal dynamics of lateral inhibition. The potential adaptive role of such choice mechanisms is discussed. PMID:26022836

  14. Equation of motion using fractional calculus

    SciTech Connect

    Kihong, Kwon.

    1991-01-01

    One-dimensional motion of a particle was studied using fractional calculus, which is the differentiation and the integration of arbitrary order. By fractional differentiation, equation of motion could be written in compact form. Fractional parameters were numerically calculated by using the known solutions of general relativistic free fall motion. Also, from the approximate forms for fractional parameters, the physical meanings were found. The fractional parameters depended on the proper time, the mass of gravitating body, and the initial radial coordinate of the particle.

  15. Gravitational acceleration as a cue for absolute size and distance?

    NASA Technical Reports Server (NTRS)

    Hecht, H.; Kaiser, M. K.; Banks, M. S.

    1996-01-01

    When an object's motion is influenced by gravity, as in the rise and fall of a thrown ball, the vertical component of acceleration is roughly constant at 9.8 m/sec2. In principle, an observer could use this information to estimate the absolute size and distance of the object (Saxberg, 1987a; Watson, Banks, von Hofsten, & Royden, 1992). In five experiments, we examined people's ability to utilize the size and distance information provided by gravitational acceleration. Observers viewed computer simulations of an object rising and falling on a trajectory aligned with the gravitational vector. The simulated objects were balls of different diameters presented across a wide range of simulated distances. Observers were asked to identify the ball that was presented and to estimate its distance. The results showed that observers were much more sensitive to average velocity than to the gravitational acceleration pattern. Likewise, verticality of the motion and visibility of the trajectory's apex had negligible effects on the accuracy of size and distance judgments.

  16. 49 CFR 109.11 - Assistance of properly qualified personnel.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... MATERIALS SAFETY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION HAZARDOUS MATERIALS AND OIL TRANSPORTATION... properly qualified to perform a function that is essential to the agent's exercise of authority under...

  17. Super-Sharp Radio "Vision" Measures Galaxy's Motion in Space

    NASA Astrophysics Data System (ADS)

    2005-03-01

    Astronomers using the National Science Foundation's Very Long Baseline Array (VLBA) have measured the motion across the sky of a galaxy nearly 2.4 million light-years from Earth. While scientists have been measuring the motion of galaxies directly toward or away from Earth for decades, this is the first time that the transverse motion (called proper motion by astronomers) has been measured for a galaxy that is not a satellite of our own Milky Way Galaxy. M33 Radio/Optical Image of M33 CREDIT: NRAO/AUI/NSF, NOAO/AURA/NSF (Click on image for more files) An international scientific team analyzed VLBA observations made over two and a half years to detect minuscule shifts in the sky position of the spiral galaxy M33. Combined with previous measurements of the galaxy's motion toward Earth, the new data allowed the astronomers to calculate M33's movement in three dimensions for the first time. "A snail crawling on Mars would appear to be moving across the surface more than 100 times faster than the motion we measured for this galaxy," said Mark Reid, of the Harvard-Smithsonian Center for Astrophysics in Cambridge, MA. M33 is a satellite of the larger galaxy M31, the well-known Andromeda Galaxy that is the most distant object visible to the naked eye. Both are part of the Local Group of galaxies that includes the Milky Way. In addition to measuring the motion of M33 as a whole, the astronomers also were able to make a direct measurement of the spiral galaxy's rotation. Both measurements were made by observing the changes in position of giant clouds of molecules inside the galaxy. The water vapor in these clouds acts as a natural maser, strengthening, or amplifying, radio emission the same way that lasers amplify light emission. The natural masers acted as bright radio beacons whose movement could be tracked by the ultra-sharp radio "vision" of the VLBA. Reid and his colleagues plan to continue measuring M33's motion and also to make similar measurements of M31's motion

  18. Motion Simulator

    NASA Technical Reports Server (NTRS)

    1993-01-01

    MOOG, Inc. supplies hydraulic actuators for the Space Shuttle. When MOOG learned NASA was interested in electric actuators for possible future use, the company designed them with assistance from Marshall Space Flight Center. They also decided to pursue the system's commercial potential. This led to partnership with InterActive Simulation, Inc. for production of cabin flight simulators for museums, expositions, etc. The resulting products, the Magic Motion Simulator 30 Series, are the first electric powered simulators. Movements are computer-guided, including free fall to heighten the sense of moving through space. A projection system provides visual effects, and the 11 speakers of a digital laser based sound system add to the realism. The electric actuators are easier to install, have lower operating costs, noise, heat and staff requirements. The U.S. Space & Rocket Center and several other organizations have purchased the simulators.

  19. Realtime Absolute Orientation with Outlier Rejection for Visual Odometry and Mesh Merging

    NASA Technical Reports Server (NTRS)

    Bandari, Esfandiar; Goldstein, Norman; Nesnas, Issa; Bajracharya, Max

    2004-01-01

    This paper addresses a high level spatio-temporal problem, namely "absolute orientation", which arises in visual-odometry (using stereo), or registering two models created by different Structure from Motion (SFM) reconstructions. We compare the very popular method due to Horn using quaternions and our own independently derive method using the orthonormal rotation matrix R. We also introduce a novel approach for outlier rejection using spectral clustering.

  20. Absolute partial photoionization cross sections of ozone.

    SciTech Connect

    Berkowitz, J.; Chemistry

    2008-04-01

    Despite the current concerns about ozone, absolute partial photoionization cross sections for this molecule in the vacuum ultraviolet (valence) region have been unavailable. By eclectic re-evaluation of old/new data and plausible assumptions, such cross sections have been assembled to fill this void.

  1. Solving Absolute Value Equations Algebraically and Geometrically

    ERIC Educational Resources Information Center

    Shiyuan, Wei

    2005-01-01

    The way in which students can improve their comprehension by understanding the geometrical meaning of algebraic equations or solving algebraic equation geometrically is described. Students can experiment with the conditions of the absolute value equation presented, for an interesting way to form an overall understanding of the concept.

  2. Teaching Absolute Value Inequalities to Mature Students

    ERIC Educational Resources Information Center

    Sierpinska, Anna; Bobos, Georgeana; Pruncut, Andreea

    2011-01-01

    This paper gives an account of a teaching experiment on absolute value inequalities, whose aim was to identify characteristics of an approach that would realize the potential of the topic to develop theoretical thinking in students enrolled in prerequisite mathematics courses at a large, urban North American university. The potential is…

  3. Increasing Capacity: Practice Effects in Absolute Identification

    ERIC Educational Resources Information Center

    Dodds, Pennie; Donkin, Christopher; Brown, Scott D.; Heathcote, Andrew

    2011-01-01

    In most of the long history of the study of absolute identification--since Miller's (1956) seminal article--a severe limit on performance has been observed, and this limit has resisted improvement even by extensive practice. In a startling result, Rouder, Morey, Cowan, and Pfaltz (2004) found substantially improved performance with practice in the…

  4. On Relative and Absolute Conviction in Mathematics

    ERIC Educational Resources Information Center

    Weber, Keith; Mejia-Ramos, Juan Pablo

    2015-01-01

    Conviction is a central construct in mathematics education research on justification and proof. In this paper, we claim that it is important to distinguish between absolute conviction and relative conviction. We argue that researchers in mathematics education frequently have not done so and this has lead to researchers making unwarranted claims…

  5. Absolute Points for Multiple Assignment Problems

    ERIC Educational Resources Information Center

    Adlakha, V.; Kowalski, K.

    2006-01-01

    An algorithm is presented to solve multiple assignment problems in which a cost is incurred only when an assignment is made at a given cell. The proposed method recursively searches for single/group absolute points to identify cells that must be loaded in any optimal solution. Unlike other methods, the first solution is the optimal solution. The…

  6. Nonequilibrium equalities in absolutely irreversible processes

    NASA Astrophysics Data System (ADS)

    Murashita, Yuto; Funo, Ken; Ueda, Masahito

    2015-03-01

    Nonequilibrium equalities have attracted considerable attention in the context of statistical mechanics and information thermodynamics. Integral nonequilibrium equalities reveal an ensemble property of the entropy production σ as = 1 . Although nonequilibrium equalities apply to rather general nonequilibrium situations, they break down in absolutely irreversible processes, where the forward-path probability vanishes and the entropy production diverges. We identify the mathematical origins of this inapplicability as the singularity of probability measure. As a result, we generalize conventional integral nonequilibrium equalities to absolutely irreversible processes as = 1 -λS , where λS is the probability of the singular part defined based on Lebesgue's decomposition theorem. The acquired equality contains two physical quantities related to irreversibility: σ characterizing ordinary irreversibility and λS describing absolute irreversibility. An inequality derived from the obtained equality demonstrates the absolute irreversibility leads to the fundamental lower bound on the entropy production. We demonstrate the validity of the obtained equality for a simple model.

  7. Stimulus Probability Effects in Absolute Identification

    ERIC Educational Resources Information Center

    Kent, Christopher; Lamberts, Koen

    2016-01-01

    This study investigated the effect of stimulus presentation probability on accuracy and response times in an absolute identification task. Three schedules of presentation were used to investigate the interaction between presentation probability and stimulus position within the set. Data from individual participants indicated strong effects of…

  8. Precision absolute positional measurement of laser beams.

    PubMed

    Fitzsimons, Ewan D; Bogenstahl, Johanna; Hough, James; Killow, Christian J; Perreur-Lloyd, Michael; Robertson, David I; Ward, Henry

    2013-04-20

    We describe an instrument which, coupled with a suitable coordinate measuring machine, facilitates the absolute measurement within the machine frame of the propagation direction of a millimeter-scale laser beam to an accuracy of around ±4 μm in position and ±20 μrad in angle. PMID:23669658

  9. Damage identification in shear-type structures using a proper orthogonal decomposition approach

    NASA Astrophysics Data System (ADS)

    Wang, Dansheng; Xiang, Wei; Zeng, Peng; Zhu, Hongping

    2015-10-01

    Proper orthogonal modes (POMs) obtained through proper orthogonal decomposition (POD), as a statistical pattern analysis technique, have been physically demonstrated to represent the dominant structure of the dynamic response data in previous study. In this paper, a novel POMs-based damage identification approach for shear-type buildings is developed. First, POMs of acceleration dynamic response of a shear-type building under Gauss White Noise (GWN) ground motion are obtained using singular value decomposition; then, the dominant POMs of acceleration response are used to identify the damage locations and severities through particle swarm optimization (PSO) algorithm. This proposed approach is applied to two three-story shear-type buildings in numerical simulation and a three-story shear-type frame in experimental study. The results demonstrate that the locations and severities of structural damage in shear-type buildings can be effectively identified by using the proposed method.

  10. Toward a generalized plate motion reference frame

    NASA Astrophysics Data System (ADS)

    Becker, T. W.; Schaeffer, A. J.; Lebedev, S.; Conrad, C. P.

    2015-05-01

    An absolute plate motion (APM) model is required to address issues such as the thermochemical evolution of Earth's mantle. All APM models have to rely on indirect inferences, including those based on hot spots and seismic anisotropy, each with their own set of uncertainties. Here, we explore a seafloor spreading-aligned reference frame. We show that this reference frame fits azimuthal seismic anisotropy in the uppermost mantle very well. The corresponding Euler pole is close to those of hot spot reference frames, ridge motion minimizing models, and geodynamic estimates of net rotation and predicts clear trench motion patterns. We conclude that a net rotation pole guided by the spreading-aligned model (at 64°E, 61°S, with moderate rotation of ˜ 0.2 … 0.3°/Myr) could indeed represent a standard, comprehensive reference frame for present-day plate motions with respect to the deep mantle.

  11. Analysis And Display Of Human Wrist Motion

    NASA Astrophysics Data System (ADS)

    Peterson, Steven W.; Erdman, Arthur G.

    1983-07-01

    The three-dimensional kinematic analysis of the wrist is a complex problem. A method utilizing high speed stereocinematography has been developed to accurately measure the motion of the bones in the wrist. Both relative and absolute motions can be obtained using this system. The system has been shown to accurately locate a point to +/- 0.003 inch. The three-dimensional motion characteristics of the capitate in radial ulnar deviation were analyzed using this system, and the results are presented. A computer graphics program, developed by the authors, is used to display the motion characteristics of the carpal bones. In this program, the bone surface, defined using a special stereopointer and bicubic surface fitting algorithms, is displayed along with the kinematic data.

  12. 32 CFR 536.27 - Identification of a proper claimant.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... withdrawn, deny the claim without delay. An example is a claim filed on behalf of a minor for loss of... a proper claimant. The following are proper claimants: (a) Claims for property loss or damage. A.... Property loss is defined as loss of actual tangible property, not consequential damage resulting from...

  13. 32 CFR 536.27 - Identification of a proper claimant.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... withdrawn, deny the claim without delay. An example is a claim filed on behalf of a minor for loss of... a proper claimant. The following are proper claimants: (a) Claims for property loss or damage. A.... Property loss is defined as loss of actual tangible property, not consequential damage resulting from...

  14. 17 CFR 162.21 - Proper disposal of consumer information.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 17 Commodity and Securities Exchanges 1 2012-04-01 2012-04-01 false Proper disposal of consumer... PROTECTION OF CONSUMER INFORMATION UNDER THE FAIR CREDIT REPORTING ACT Disposal Rules § 162.21 Proper disposal of consumer information. (a) In general. Any covered affiliate must adopt must adopt...

  15. 17 CFR 162.21 - Proper disposal of consumer information.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 17 Commodity and Securities Exchanges 1 2013-04-01 2013-04-01 false Proper disposal of consumer... PROTECTION OF CONSUMER INFORMATION UNDER THE FAIR CREDIT REPORTING ACT Disposal Rules § 162.21 Proper disposal of consumer information. (a) In general. Any covered affiliate must adopt must adopt...

  16. 17 CFR 162.21 - Proper disposal of consumer information.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 17 Commodity and Securities Exchanges 2 2014-04-01 2014-04-01 false Proper disposal of consumer... (CONTINUED) PROTECTION OF CONSUMER INFORMATION UNDER THE FAIR CREDIT REPORTING ACT Disposal Rules § 162.21 Proper disposal of consumer information. (a) In general. Any covered affiliate must adopt must...

  17. Second Language Listening and Unfamiliar Proper Names: Comprehension Barrier?

    ERIC Educational Resources Information Center

    Kobeleva, Polina P.

    2012-01-01

    This study examines whether unfamiliar proper names affect English as a second language (ESL) learners' listening comprehension. A total of 110 intermediate to advanced ESL learners participated; comprehension of a short news text was tested under two conditions, Names Known (all proper names pre-taught in advance) and Names Unknown (all proper…

  18. Secular perturbation theory and computation of asteroid proper elements

    NASA Technical Reports Server (NTRS)

    Milani, Andrea; Knezevic, Zoran

    1991-01-01

    A new theory for the calculation of proper elements is presented. This theory defines an explicit algorithm applicable to any chosen set of orbits and accounts for the effect of shallow resonances on secular frequencies. The proper elements are computed with an iterative algorithm and the behavior of the iteration can be used to define a quality code.

  19. Participation in "Handwashing University" Promotes Proper Handwashing Techniques for Youth

    ERIC Educational Resources Information Center

    Fenton, Ginger; Radhakrishna, Rama; Cutter, Catherine Nettles

    2010-01-01

    A study was conducted to assess the effectiveness of the Handwashing University on teaching youth the benefits of proper handwashing. The Handwashing University is an interactive display with several successive stations through which participants move to learn necessary skills for proper handwashing. Upon completion of the Handwashing University,…

  20. 16 CFR 682.3 - Proper disposal of consumer information.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 16 Commercial Practices 1 2010-01-01 2010-01-01 false Proper disposal of consumer information. 682... OF CONSUMER REPORT INFORMATION AND RECORDS § 682.3 Proper disposal of consumer information. (a) Standard. Any person who maintains or otherwise possesses consumer information for a business purpose...

  1. Educating Children to Proper Eating Habits in the Classroom.

    ERIC Educational Resources Information Center

    King, Marian

    A brief discussion of proper nutrition in general precedes an examination of proper nutrition for school children and the specification of nutrition education objectives for kindergarten or first grade students. The remainder of the paper delineates food projects by which objectives can be realized (for example, snack necklace, jack-o-lantern…

  2. 17 CFR 230.401 - Requirements as to proper form.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 17 Commodity and Securities Exchanges 2 2010-04-01 2010-04-01 false Requirements as to proper form... RULES AND REGULATIONS, SECURITIES ACT OF 1933 General Requirements § 230.401 Requirements as to proper... applicable rules and forms as in effect on the initial filing date of such registration statement...

  3. 17 CFR 230.401 - Requirements as to proper form.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 17 Commodity and Securities Exchanges 2 2013-04-01 2013-04-01 false Requirements as to proper form... RULES AND REGULATIONS, SECURITIES ACT OF 1933 General Requirements § 230.401 Requirements as to proper... applicable rules and forms as in effect on the initial filing date of such registration statement...

  4. 29 CFR 1404.20 - Proper use of expedited arbitration.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 29 Labor 4 2011-07-01 2011-07-01 false Proper use of expedited arbitration. 1404.20 Section 1404... ARBITRATION SERVICES Expedited Arbitration § 1404.20 Proper use of expedited arbitration. (a) FMCS reserves the right to cease honoring request for Expedited Arbitration if a pattern of misuse of this...

  5. 25 CFR 213.35 - Mines to be timbered properly.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 25 Indians 1 2011-04-01 2011-04-01 false Mines to be timbered properly. 213.35 Section 213.35... LANDS OF MEMBERS OF FIVE CIVILIZED TRIBES, OKLAHOMA, FOR MINING Operations § 213.35 Mines to be timbered properly. In mining operations the lessee shall keep the mine well and sufficiently timbered at all...

  6. 25 CFR 213.35 - Mines to be timbered properly.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 25 Indians 1 2010-04-01 2010-04-01 false Mines to be timbered properly. 213.35 Section 213.35... LANDS OF MEMBERS OF FIVE CIVILIZED TRIBES, OKLAHOMA, FOR MINING Operations § 213.35 Mines to be timbered properly. In mining operations the lessee shall keep the mine well and sufficiently timbered at all...

  7. 25 CFR 213.35 - Mines to be timbered properly.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 25 Indians 1 2013-04-01 2013-04-01 false Mines to be timbered properly. 213.35 Section 213.35... LANDS OF MEMBERS OF FIVE CIVILIZED TRIBES, OKLAHOMA, FOR MINING Operations § 213.35 Mines to be timbered properly. In mining operations the lessee shall keep the mine well and sufficiently timbered at all...

  8. 25 CFR 213.35 - Mines to be timbered properly.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 25 Indians 1 2012-04-01 2011-04-01 true Mines to be timbered properly. 213.35 Section 213.35... LANDS OF MEMBERS OF FIVE CIVILIZED TRIBES, OKLAHOMA, FOR MINING Operations § 213.35 Mines to be timbered properly. In mining operations the lessee shall keep the mine well and sufficiently timbered at all...

  9. 25 CFR 213.35 - Mines to be timbered properly.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 25 Indians 1 2014-04-01 2014-04-01 false Mines to be timbered properly. 213.35 Section 213.35... LANDS OF MEMBERS OF FIVE CIVILIZED TRIBES, OKLAHOMA, FOR MINING Operations § 213.35 Mines to be timbered properly. In mining operations the lessee shall keep the mine well and sufficiently timbered at all...

  10. 29 CFR 1404.20 - Proper use of expedited arbitration.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 29 Labor 4 2010-07-01 2010-07-01 false Proper use of expedited arbitration. 1404.20 Section 1404... ARBITRATION SERVICES Expedited Arbitration § 1404.20 Proper use of expedited arbitration. (a) FMCS reserves the right to cease honoring request for Expedited Arbitration if a pattern of misuse of this...

  11. 49 CFR 236.526 - Roadway element not functioning properly.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 4 2013-10-01 2013-10-01 false Roadway element not functioning properly. 236.526... element not functioning properly. When a roadway element except track circuit of automatic train stop... roadway element shall be caused manually to display its most restrictive aspect until such element...

  12. 49 CFR 236.526 - Roadway element not functioning properly.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 4 2014-10-01 2014-10-01 false Roadway element not functioning properly. 236.526... element not functioning properly. When a roadway element except track circuit of automatic train stop... roadway element shall be caused manually to display its most restrictive aspect until such element...

  13. 49 CFR 236.526 - Roadway element not functioning properly.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 4 2012-10-01 2012-10-01 false Roadway element not functioning properly. 236.526... element not functioning properly. When a roadway element except track circuit of automatic train stop... roadway element shall be caused manually to display its most restrictive aspect until such element...

  14. 49 CFR 236.526 - Roadway element not functioning properly.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 4 2011-10-01 2011-10-01 false Roadway element not functioning properly. 236.526... element not functioning properly. When a roadway element except track circuit of automatic train stop... roadway element shall be caused manually to display its most restrictive aspect until such element...

  15. 49 CFR 236.526 - Roadway element not functioning properly.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Roadway element not functioning properly. 236.526... element not functioning properly. When a roadway element except track circuit of automatic train stop... roadway element shall be caused manually to display its most restrictive aspect until such element...

  16. Human sensitivity to vertical self-motion.

    PubMed

    Nesti, Alessandro; Barnett-Cowan, Michael; Macneilage, Paul R; Bülthoff, Heinrich H

    2014-01-01

    Perceiving vertical self-motion is crucial for maintaining balance as well as for controlling an aircraft. Whereas heave absolute thresholds have been exhaustively studied, little work has been done in investigating how vertical sensitivity depends on motion intensity (i.e., differential thresholds). Here we measure human sensitivity for 1-Hz sinusoidal accelerations for 10 participants in darkness. Absolute and differential thresholds are measured for upward and downward translations independently at 5 different peak amplitudes ranging from 0 to 2 m/s(2). Overall vertical differential thresholds are higher than horizontal differential thresholds found in the literature. Psychometric functions are fit in linear and logarithmic space, with goodness of fit being similar in both cases. Differential thresholds are higher for upward as compared to downward motion and increase with stimulus intensity following a trend best described by two power laws. The power laws' exponents of 0.60 and 0.42 for upward and downward motion, respectively, deviate from Weber's Law in that thresholds increase less than expected at high stimulus intensity. We speculate that increased sensitivity at high accelerations and greater sensitivity to downward than upward self-motion may reflect adaptations to avoid falling. PMID:24158607

  17. Combined Use of Absolute and Differential Seismic Arrival Time Data to Improve Absolute Event Location

    NASA Astrophysics Data System (ADS)

    Myers, S.; Johannesson, G.

    2012-12-01

    Arrival time measurements based on waveform cross correlation are becoming more common as advanced signal processing methods are applied to seismic data archives and real-time data streams. Waveform correlation can precisely measure the time difference between the arrival of two phases, and differential time data can be used to constrain relative location of events. Absolute locations are needed for many applications, which generally requires the use of absolute time data. Current methods for measuring absolute time data are approximately two orders of magnitude less precise than differential time measurements. To exploit the strengths of both absolute and differential time data, we extend our multiple-event location method Bayesloc, which previously used absolute time data only, to include the use of differential time measurements that are based on waveform cross correlation. Fundamentally, Bayesloc is a formulation of the joint probability over all parameters comprising the multiple event location system. The Markov-Chain Monte Carlo method is used to sample from the joint probability distribution given arrival data sets. The differential time component of Bayesloc includes scaling a stochastic estimate of differential time measurement precision based the waveform correlation coefficient for each datum. For a regional-distance synthetic data set with absolute and differential time measurement error of 0.25 seconds and 0.01 second, respectively, epicenter location accuracy is improved from and average of 1.05 km when solely absolute time data are used to 0.28 km when absolute and differential time data are used jointly (73% improvement). The improvement in absolute location accuracy is the result of conditionally limiting absolute location probability regions based on the precise relative position with respect to neighboring events. Bayesloc estimates of data precision are found to be accurate for the synthetic test, with absolute and differential time measurement

  18. Chromosomal locus tracking with proper accounting of static and dynamic errors.

    PubMed

    Backlund, Mikael P; Joyner, Ryan; Moerner, W E

    2015-06-01

    The mean-squared displacement (MSD) and velocity autocorrelation (VAC) of tracked single particles or molecules are ubiquitous metrics for extracting parameters that describe the object's motion, but they are both corrupted by experimental errors that hinder the quantitative extraction of underlying parameters. For the simple case of pure Brownian motion, the effects of localization error due to photon statistics ("static error") and motion blur due to finite exposure time ("dynamic error") on the MSD and VAC are already routinely treated. However, particles moving through complex environments such as cells, nuclei, or polymers often exhibit anomalous diffusion, for which the effects of these errors are less often sufficiently treated. We present data from tracked chromosomal loci in yeast that demonstrate the necessity of properly accounting for both static and dynamic error in the context of an anomalous diffusion that is consistent with a fractional Brownian motion (FBM). We compare these data to analytical forms of the expected values of the MSD and VAC for a general FBM in the presence of these errors. PMID:26172745

  19. Chromosomal locus tracking with proper accounting of static and dynamic errors

    NASA Astrophysics Data System (ADS)

    Backlund, Mikael P.; Joyner, Ryan; Moerner, W. E.

    2015-06-01

    The mean-squared displacement (MSD) and velocity autocorrelation (VAC) of tracked single particles or molecules are ubiquitous metrics for extracting parameters that describe the object's motion, but they are both corrupted by experimental errors that hinder the quantitative extraction of underlying parameters. For the simple case of pure Brownian motion, the effects of localization error due to photon statistics ("static error") and motion blur due to finite exposure time ("dynamic error") on the MSD and VAC are already routinely treated. However, particles moving through complex environments such as cells, nuclei, or polymers often exhibit anomalous diffusion, for which the effects of these errors are less often sufficiently treated. We present data from tracked chromosomal loci in yeast that demonstrate the necessity of properly accounting for both static and dynamic error in the context of an anomalous diffusion that is consistent with a fractional Brownian motion (FBM). We compare these data to analytical forms of the expected values of the MSD and VAC for a general FBM in the presence of these errors.

  20. Collective motion

    NASA Astrophysics Data System (ADS)

    Vicsek, Tamás; Zafeiris, Anna

    2012-08-01

    We review the observations and the basic laws describing the essential aspects of collective motion - being one of the most common and spectacular manifestation of coordinated behavior. Our aim is to provide a balanced discussion of the various facets of this highly multidisciplinary field, including experiments, mathematical methods and models for simulations, so that readers with a variety of background could get both the basics and a broader, more detailed picture of the field. The observations we report on include systems consisting of units ranging from macromolecules through metallic rods and robots to groups of animals and people. Some emphasis is put on models that are simple and realistic enough to reproduce the numerous related observations and are useful for developing concepts for a better understanding of the complexity of systems consisting of many simultaneously moving entities. As such, these models allow the establishing of a few fundamental principles of flocking. In particular, it is demonstrated, that in spite of considerable differences, a number of deep analogies exist between equilibrium statistical physics systems and those made of self-propelled (in most cases living) units. In both cases only a few well defined macroscopic/collective states occur and the transitions between these states follow a similar scenario, involving discontinuity and algebraic divergences.

  1. Asteroid proper elements and the dynamical structure of the asteroid main belt

    NASA Astrophysics Data System (ADS)

    Milani, A.; Knezevic, Z.

    1994-02-01

    We have computed proper elements for 12,573 asteroids, including all the ones with orbits accurate enough to be useful for family identification. This was done with an upgraded version of our iterative analytical algorithm, resulting in significantly improved accuracy for most asteroids in the low to moderate inclination and eccentricity region of the main belt (typical instability in the proper e and sin I being less than or = 0.0015 over 5 Myr). This stability has been verified by numerical integrations (within a realistic model) of 35 test cases. In a small percentage of cases, the accuracy of the proper elements computation was degraded by the effects of some resonance, either in mean motion or secular. We have been able to list the resonances responsible for this degradation in almost all the cases, in such a way that these are properly flagged with a 'resonance code.' This list of resonances, including nine high-degree secular resonances not known before our work, provides a detailed map of the dynamical structure of the asteroid main belt. We investigate the long-term dynamics of some of these secular resonances and find both very large amplitude oscillations of the eccentricity and irregular behavior for asteroids affected by one or more resonances. We show the geometry of these resonances in the proper elements space and their relationship with the asteroid distribution and with the most prominent families. In the second part of the paper, we give a detailed description of the improvements of this version of the proper elements theory with respect to the previously published ones. (A. Milani and Z. Knezevic, 1990, 1992). We discuss the success of some of these improvements in cases which were previously of degraded accuracy, and we also comment on the failure of some attempted improvements. We conjecture that our theory is very close to the fundamental limitations to the accuracy of any analytical theory, which result from the fact that there is an

  2. Absolute and relative dosimetry for ELIMED

    SciTech Connect

    Cirrone, G. A. P.; Schillaci, F.; Scuderi, V.; Cuttone, G.; Candiano, G.; Musumarra, A.; Pisciotta, P.; Romano, F.; Carpinelli, M.; Presti, D. Lo; Raffaele, L.; Tramontana, A.; Cirio, R.; Sacchi, R.; Monaco, V.; Marchetto, F.; Giordanengo, S.

    2013-07-26

    The definition of detectors, methods and procedures for the absolute and relative dosimetry of laser-driven proton beams is a crucial step toward the clinical use of this new kind of beams. Hence, one of the ELIMED task, will be the definition of procedures aiming to obtain an absolute dose measure at the end of the transport beamline with an accuracy as close as possible to the one required for clinical applications (i.e. of the order of 5% or less). Relative dosimetry procedures must be established, as well: they are necessary in order to determine and verify the beam dose distributions and to monitor the beam fluence and the energetic spectra during irradiations. Radiochromic films, CR39, Faraday Cup, Secondary Emission Monitor (SEM) and transmission ionization chamber will be considered, designed and studied in order to perform a fully dosimetric characterization of the ELIMED proton beam.

  3. Probing absolute spin polarization at the nanoscale.

    PubMed

    Eltschka, Matthias; Jäck, Berthold; Assig, Maximilian; Kondrashov, Oleg V; Skvortsov, Mikhail A; Etzkorn, Markus; Ast, Christian R; Kern, Klaus

    2014-12-10

    Probing absolute values of spin polarization at the nanoscale offers insight into the fundamental mechanisms of spin-dependent transport. Employing the Zeeman splitting in superconducting tips (Meservey-Tedrow-Fulde effect), we introduce a novel spin-polarized scanning tunneling microscopy that combines the probing capability of the absolute values of spin polarization with precise control at the atomic scale. We utilize our novel approach to measure the locally resolved spin polarization of magnetic Co nanoislands on Cu(111). We find that the spin polarization is enhanced by 65% when increasing the width of the tunnel barrier by only 2.3 Å due to the different decay of the electron orbitals into vacuum. PMID:25423049

  4. Absolute-magnitude distributions of supernovae

    SciTech Connect

    Richardson, Dean; Wright, John; Jenkins III, Robert L.; Maddox, Larry

    2014-05-01

    The absolute-magnitude distributions of seven supernova (SN) types are presented. The data used here were primarily taken from the Asiago Supernova Catalogue, but were supplemented with additional data. We accounted for both foreground and host-galaxy extinction. A bootstrap method is used to correct the samples for Malmquist bias. Separately, we generate volume-limited samples, restricted to events within 100 Mpc. We find that the superluminous events (M{sub B} < –21) make up only about 0.1% of all SNe in the bias-corrected sample. The subluminous events (M{sub B} > –15) make up about 3%. The normal Ia distribution was the brightest with a mean absolute blue magnitude of –19.25. The IIP distribution was the dimmest at –16.75.

  5. Absolute radiometry and the solar constant

    NASA Technical Reports Server (NTRS)

    Willson, R. C.

    1974-01-01

    A series of active cavity radiometers (ACRs) are described which have been developed as standard detectors for the accurate measurement of irradiance in absolute units. It is noted that the ACR is an electrical substitution calorimeter, is designed for automatic remote operation in any environment, and can make irradiance measurements in the range from low-level IR fluxes up to 30 solar constants with small absolute uncertainty. The instrument operates in a differential mode by chopping the radiant flux to be measured at a slow rate, and irradiance is determined from two electrical power measurements together with the instrumental constant. Results are reported for measurements of the solar constant with two types of ACRs. The more accurate measurement yielded a value of 136.6 plus or minus 0.7 mW/sq cm (1.958 plus or minus 0.010 cal/sq cm per min).

  6. Asteroid absolute magnitudes and slope parameters

    NASA Technical Reports Server (NTRS)

    Tedesco, Edward F.

    1991-01-01

    A new listing of absolute magnitudes (H) and slope parameters (G) has been created and published in the Minor Planet Circulars; this same listing will appear in the 1992 Ephemerides of Minor Planets. Unlike previous listings, the values of the current list were derived from fits of data at the V band. All observations were reduced in the same fashion using, where appropriate, a single basis default value of 0.15 for the slope parameter. Distances and phase angles were computed for each observation. The data for 113 asteroids was of sufficiently high quality to permit derivation of their H and G. These improved absolute magnitudes and slope parameters will be used to deduce the most reliable bias-corrected asteroid size-frequency distribution yet made.

  7. Absolute calibration of TFTR helium proportional counters

    SciTech Connect

    Strachan, J.D.; Diesso, M.; Jassby, D.; Johnson, L.; McCauley, S.; Munsat, T.; Roquemore, A.L.; Barnes, C.W. |; Loughlin, M. |

    1995-06-01

    The TFTR helium proportional counters are located in the central five (5) channels of the TFTR multichannel neutron collimator. These detectors were absolutely calibrated using a 14 MeV neutron generator positioned at the horizontal midplane of the TFTR vacuum vessel. The neutron generator position was scanned in centimeter steps to determine the collimator aperture width to 14 MeV neutrons and the absolute sensitivity of each channel. Neutron profiles were measured for TFTR plasmas with time resolution between 5 msec and 50 msec depending upon count rates. The He detectors were used to measure the burnup of 1 MeV tritons in deuterium plasmas, the transport of tritium in trace tritium experiments, and the residual tritium levels in plasmas following 50:50 DT experiments.

  8. Absolute enantioselective separation: optical activity ex machina.

    PubMed

    Bielski, Roman; Tencer, Michal

    2005-11-01

    The paper describes methodology of using three independent macroscopic factors affecting molecular orientation to accomplish separation of a racemic mixture without the presence of any other chiral compounds, i. e., absolute enantioselective separation (AES) which is an extension of a concept of applying these factors to absolute asymmetric synthesis. The three factors may be applied simultaneously or, if their effects can be retained, consecutively. The resulting three mutually orthogonal or near orthogonal directors constitute a true chiral influence and their scalar triple product is the measure of the chirality of the system. AES can be executed in a chromatography-like microfluidic process in the presence of an electric field. It may be carried out on a chemically modified flat surface, a monolithic polymer column made of a mesoporous material, each having imparted directional properties. Separation parameters were estimated for these media and possible implications for the natural homochirality are discussed. PMID:16342798

  9. An absolute measure for a key currency

    NASA Astrophysics Data System (ADS)

    Oya, Shunsuke; Aihara, Kazuyuki; Hirata, Yoshito

    It is generally considered that the US dollar and the euro are the key currencies in the world and in Europe, respectively. However, there is no absolute general measure for a key currency. Here, we investigate the 24-hour periodicity of foreign exchange markets using a recurrence plot, and define an absolute measure for a key currency based on the strength of the periodicity. Moreover, we analyze the time evolution of this measure. The results show that the credibility of the US dollar has not decreased significantly since the Lehman shock, when the Lehman Brothers bankrupted and influenced the economic markets, and has increased even relatively better than that of the euro and that of the Japanese yen.

  10. From Hubble's NGSL to Absolute Fluxes

    NASA Technical Reports Server (NTRS)

    Heap, Sara R.; Lindler, Don

    2012-01-01

    Hubble's Next Generation Spectral Library (NGSL) consists of R-l000 spectra of 374 stars of assorted temperature, gravity, and metallicity. Each spectrum covers the wavelength range, 0.18-1.00 microns. The library can be viewed and/or downloaded from the website, http://archive.stsci.edu/prepds/stisngsll. Stars in the NGSL are now being used as absolute flux standards at ground-based observatories. However, the uncertainty in the absolute flux is about 2%, which does not meet the requirements of dark-energy surveys. We are therefore developing an observing procedure that should yield fluxes with uncertainties less than 1 % and will take part in an HST proposal to observe up to 15 stars using this new procedure.

  11. Auditory motion affects visual biological motion processing.

    PubMed

    Brooks, A; van der Zwan, R; Billard, A; Petreska, B; Clarke, S; Blanke, O

    2007-02-01

    The processing of biological motion is a critical, everyday task performed with remarkable efficiency by human sensory systems. Interest in this ability has focused to a large extent on biological motion processing in the visual modality (see, for example, Cutting, J. E., Moore, C., & Morrison, R. (1988). Masking the motions of human gait. Perception and Psychophysics, 44(4), 339-347). In naturalistic settings, however, it is often the case that biological motion is defined by input to more than one sensory modality. For this reason, here in a series of experiments we investigate behavioural correlates of multisensory, in particular audiovisual, integration in the processing of biological motion cues. More specifically, using a new psychophysical paradigm we investigate the effect of suprathreshold auditory motion on perceptions of visually defined biological motion. Unlike data from previous studies investigating audiovisual integration in linear motion processing [Meyer, G. F. & Wuerger, S. M. (2001). Cross-modal integration of auditory and visual motion signals. Neuroreport, 12(11), 2557-2560; Wuerger, S. M., Hofbauer, M., & Meyer, G. F. (2003). The integration of auditory and motion signals at threshold. Perception and Psychophysics, 65(8), 1188-1196; Alais, D. & Burr, D. (2004). No direction-specific bimodal facilitation for audiovisual motion detection. Cognitive Brain Research, 19, 185-194], we report the existence of direction-selective effects: relative to control (stationary) auditory conditions, auditory motion in the same direction as the visually defined biological motion target increased its detectability, whereas auditory motion in the opposite direction had the inverse effect. Our data suggest these effects do not arise through general shifts in visuo-spatial attention, but instead are a consequence of motion-sensitive, direction-tuned integration mechanisms that are, if not unique to biological visual motion, at least not common to all types of

  12. Super-Sharp Radio "Vision" Measures Galaxy's Motion in Space

    NASA Astrophysics Data System (ADS)

    2005-03-01

    Astronomers using the National Science Foundation's Very Long Baseline Array (VLBA) have measured the motion across the sky of a galaxy nearly 2.4 million light-years from Earth. While scientists have been measuring the motion of galaxies directly toward or away from Earth for decades, this is the first time that the transverse motion (called proper motion by astronomers) has been measured for a galaxy that is not a satellite of our own Milky Way Galaxy. M33 Radio/Optical Image of M33 CREDIT: NRAO/AUI/NSF, NOAO/AURA/NSF (Click on image for more files) An international scientific team analyzed VLBA observations made over two and a half years to detect minuscule shifts in the sky position of the spiral galaxy M33. Combined with previous measurements of the galaxy's motion toward Earth, the new data allowed the astronomers to calculate M33's movement in three dimensions for the first time. "A snail crawling on Mars would appear to be moving across the surface more than 100 times faster than the motion we measured for this galaxy," said Mark Reid, of the Harvard-Smithsonian Center for Astrophysics in Cambridge, MA. M33 is a satellite of the larger galaxy M31, the well-known Andromeda Galaxy that is the most distant object visible to the naked eye. Both are part of the Local Group of galaxies that includes the Milky Way. In addition to measuring the motion of M33 as a whole, the astronomers also were able to make a direct measurement of the spiral galaxy's rotation. Both measurements were made by observing the changes in position of giant clouds of molecules inside the galaxy. The water vapor in these clouds acts as a natural maser, strengthening, or amplifying, radio emission the same way that lasers amplify light emission. The natural masers acted as bright radio beacons whose movement could be tracked by the ultra-sharp radio "vision" of the VLBA. Reid and his colleagues plan to continue measuring M33's motion and also to make similar measurements of M31's motion

  13. Metallic Magnetic Calorimeters for Absolute Activity Measurement

    NASA Astrophysics Data System (ADS)

    Loidl, M.; Leblanc, E.; Rodrigues, M.; Bouchard, J.; Censier, B.; Branger, T.; Lacour, D.

    2008-05-01

    We present a prototype of metallic magnetic calorimeters that we are developing for absolute activity measurements of low energy emitting radionuclides. We give a detailed description of the realization of the prototype, containing an 55Fe source inside the detector absorber. We present the analysis of first data taken with this detector and compare the result of activity measurement with liquid scintillation counting. We also propose some ways for reducing the uncertainty on the activity determination with this new technique.

  14. Absolute photoionization cross sections of atomic oxygen

    NASA Technical Reports Server (NTRS)

    Samson, J. A. R.; Pareek, P. N.

    1985-01-01

    The absolute values of photoionization cross sections of atomic oxygen were measured from the ionization threshold to 120 A. An auto-ionizing resonance belonging to the 2S2P4(4P)3P(3Do, 3So) transition was observed at 479.43 A and another line at 389.97 A. The experimental data is in excellent agreement with rigorous close-coupling calculations that include electron correlations in both the initial and final states.

  15. Absolute photoionization cross sections of atomic oxygen

    NASA Technical Reports Server (NTRS)

    Samson, J. A. R.; Pareek, P. N.

    1982-01-01

    The absolute values of photoionization cross sections of atomic oxygen were measured from the ionization threshold to 120 A. An auto-ionizing resonance belonging to the 2S2P4(4P)3P(3Do, 3So) transition was observed at 479.43 A and another line at 389.97 A. The experimental data is in excellent agreement with rigorous close-coupling calculations that include electron correlations in both the initial and final states.

  16. Silicon Absolute X-Ray Detectors

    SciTech Connect

    Seely, John F.; Korde, Raj; Sprunck, Jacob; Medjoubi, Kadda; Hustache, Stephanie

    2010-06-23

    The responsivity of silicon photodiodes having no loss in the entrance window, measured using synchrotron radiation in the 1.75 to 60 keV range, was compared to the responsivity calculated using the silicon thickness measured using near-infrared light. The measured and calculated responsivities agree with an average difference of 1.3%. This enables their use as absolute x-ray detectors.

  17. Blood pressure targets and absolute cardiovascular risk.

    PubMed

    Odutayo, Ayodele; Rahimi, Kazem; Hsiao, Allan J; Emdin, Connor A

    2015-08-01

    In the Eighth Joint National Committee guideline on hypertension, the threshold for the initiation of blood pressure-lowering treatment for elderly adults (≥60 years) without chronic kidney disease or diabetes mellitus was raised from 140/90 mm Hg to 150/90 mm Hg. However, the committee was not unanimous in this decision, particularly because a large proportion of adults ≥60 years may be at high cardiovascular risk. On the basis of Eighth Joint National Committee guideline, we sought to determine the absolute 10-year risk of cardiovascular disease among these adults through analyzing the National Health and Nutrition Examination Survey (2005-2012). The primary outcome measure was the proportion of adults who were at ≥20% predicted absolute cardiovascular risk and above goals for the Seventh Joint National Committee guideline but reclassified as at target under the Eighth Joint National Committee guideline (reclassified). The Framingham General Cardiovascular Disease Risk Score was used. From 2005 to 2012, the surveys included 12 963 adults aged 30 to 74 years with blood pressure measurements, of which 914 were reclassified based on the guideline. Among individuals reclassified as not in need of additional treatment, the proportion of adults 60 to 74 years without chronic kidney disease or diabetes mellitus at ≥20% absolute risk was 44.8%. This corresponds to 0.8 million adults. The proportion at high cardiovascular risk remained sizable among adults who were not receiving blood pressure-lowering treatment. Taken together, a sizable proportion of reclassified adults 60 to 74 years without chronic kidney disease or diabetes mellitus was at ≥20% absolute cardiovascular risk. PMID:26056340

  18. Relative errors can cue absolute visuomotor mappings.

    PubMed

    van Dam, Loes C J; Ernst, Marc O

    2015-12-01

    When repeatedly switching between two visuomotor mappings, e.g. in a reaching or pointing task, adaptation tends to speed up over time. That is, when the error in the feedback corresponds to a mapping switch, fast adaptation occurs. Yet, what is learned, the relative error or the absolute mappings? When switching between mappings, errors with a size corresponding to the relative difference between the mappings will occur more often than other large errors. Thus, we could learn to correct more for errors with this familiar size (Error Learning). On the other hand, it has been shown that the human visuomotor system can store several absolute visuomotor mappings (Mapping Learning) and can use associated contextual cues to retrieve them. Thus, when contextual information is present, no error feedback is needed to switch between mappings. Using a rapid pointing task, we investigated how these two types of learning may each contribute when repeatedly switching between mappings in the absence of task-irrelevant contextual cues. After training, we examined how participants changed their behaviour when a single error probe indicated either the often-experienced error (Error Learning) or one of the previously experienced absolute mappings (Mapping Learning). Results were consistent with Mapping Learning despite the relative nature of the error information in the feedback. This shows that errors in the feedback can have a double role in visuomotor behaviour: they drive the general adaptation process by making corrections possible on subsequent movements, as well as serve as contextual cues that can signal a learned absolute mapping. PMID:26280315

  19. Absolute distance measurements by variable wavelength interferometry

    NASA Astrophysics Data System (ADS)

    Bien, F.; Camac, M.; Caulfield, H. J.; Ezekiel, S.

    1981-02-01

    This paper describes a laser interferometer which provides absolute distance measurements using tunable lasers. An active feedback loop system, in which the laser frequency is locked to the optical path length difference of the interferometer, is used to tune the laser wavelengths. If the two wavelengths are very close, electronic frequency counters can be used to measure the beat frequency between the two laser frequencies and thus to determine the optical path difference between the two legs of the interferometer.

  20. Absolute dosimetry for extreme-ultraviolet lithography

    NASA Astrophysics Data System (ADS)

    Berger, Kurt W.; Campiotti, Richard H.

    2000-06-01

    The accurate measurement of an exposure dose reaching the wafer on an extreme ultraviolet (EUV) lithographic system has been a technical challenge directly applicable to the evaluation of candidate EUV resist materials and calculating lithography system throughputs. We have developed a dose monitoring sensor system that can directly measure EUV intensities at the wafer plane of a prototype EUV lithographic system. This sensor system, located on the wafer stage adjacent to the electrostatic chuck used to grip wafers, operates by translating the sensor into the aerial image, typically illuminating an 'open' (unpatterned) area on the reticle. The absolute signal strength can be related to energy density at the wafer, and thus used to determine resist sensitivity, and the signal as a function of position can be used to determine illumination uniformity at the wafer plane. Spectral filtering to enhance the detection of 13.4 nm radiation was incorporated into the sensor. Other critical design parameters include the packaging and amplification technologies required to place this device into the space and vacuum constraints of a EUV lithography environment. We describe two approaches used to determine the absolute calibration of this sensor. The first conventional approach requires separate characterization of each element of the sensor. A second novel approach uses x-ray emission from a mildly radioactive iron source to calibrate the absolute response of the entire sensor system (detector and electronics) in a single measurement.

  1. Early Improper Motion Detection in Golf Swings Using Wearable Motion Sensors: The First Approach

    PubMed Central

    Stančin, Sara; Tomažič, Sašo

    2013-01-01

    This paper presents an analysis of a golf swing to detect improper motion in the early phase of the swing. Led by the desire to achieve a consistent shot outcome, a particular golfer would (in multiple trials) prefer to perform completely identical golf swings. In reality, some deviations from the desired motion are always present due to the comprehensive nature of the swing motion. Swing motion deviations that are not detrimental to performance are acceptable. This analysis is conducted using a golfer's leading arm kinematic data, which are obtained from a golfer wearing a motion sensor that is comprised of gyroscopes and accelerometers. Applying the principal component analysis (PCA) to the reference observations of properly performed swings, the PCA components of acceptable swing motion deviations are established. Using these components, the motion deviations in the observations of other swings are examined. Any unacceptable deviations that are detected indicate an improper swing motion. Arbitrarily long observations of an individual player's swing sequences can be included in the analysis. The results obtained for the considered example show an improper swing motion in early phase of the swing, i.e., the first part of the backswing. An early detection method for improper swing motions that is conducted on an individual basis provides assistance for performance improvement. PMID:23752563

  2. Early improper motion detection in golf swings using wearable motion sensors: the first approach.

    PubMed

    Stančin, Sara; Tomažič, Sašo

    2013-01-01

    This paper presents an analysis of a golf swing to detect improper motion in the early phase of the swing. Led by the desire to achieve a consistent shot outcome, a particular golfer would (in multiple trials) prefer to perform completely identical golf swings. In reality, some deviations from the desired motion are always present due to the comprehensive nature of the swing motion. Swing motion deviations that are not detrimental to performance are acceptable. This analysis is conducted using a golfer's leading arm kinematic data, which are obtained from a golfer wearing a motion sensor that is comprised of gyroscopes and accelerometers. Applying the principal component analysis (PCA) to the reference observations of properly performed swings, the PCA components of acceptable swing motion deviations are established. Using these components, the motion deviations in the observations of other swings are examined. Any unacceptable deviations that are detected indicate an improper swing motion. Arbitrarily long observations of an individual player's swing sequences can be included in the analysis. The results obtained for the considered example show an improper swing motion in early phase of the swing, i.e., the first part of the backswing. An early detection method for improper swing motions that is conducted on an individual basis provides assistance for performance improvement. PMID:23752563

  3. Limited range of motion

    MedlinePlus

    Limited range of motion is a term meaning that a joint or body part cannot move through its normal range of motion. ... Motion may be limited because of a problem within the joint, swelling of tissue around the joint, ...

  4. Self Motion Perception and Motion Sickness

    NASA Technical Reports Server (NTRS)

    Fox, Robert A. (Principal Investigator)

    1991-01-01

    The studies conducted in this research project examined several aspects of motion sickness in animal models. A principle objective of these studies was to investigate the neuroanatomy that is important in motion sickness with the objectives of examining both the utility of putative models and defining neural mechanisms that are important in motion sickness.

  5. 49 CFR 109.11 - Assistance of properly qualified personnel.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... MATERIALS SAFETY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION HAZARDOUS MATERIALS AND OIL TRANSPORTATION... this part if the agent is not properly qualified to perform a function that is essential to the...

  6. 49 CFR 109.11 - Assistance of properly qualified personnel.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... MATERIALS SAFETY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION HAZARDOUS MATERIALS AND OIL TRANSPORTATION... this part if the agent is not properly qualified to perform a function that is essential to the...

  7. 49 CFR 109.11 - Assistance of properly qualified personnel.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... MATERIALS SAFETY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION HAZARDOUS MATERIALS AND OIL TRANSPORTATION... conducted under this part if the agent is not properly qualified to perform a function that is essential...

  8. Proper Use of Audio-Visual Aids: Essential for Educators.

    ERIC Educational Resources Information Center

    Dejardin, Conrad

    1989-01-01

    Criticizes educators as the worst users of audio-visual aids and among the worst public speakers. Offers guidelines for the proper use of an overhead projector and the development of transparencies. (DMM)

  9. A properly adjusted forage harvester can save time and money

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A properly adjusted forage harvester can save fuel and increase the realizable milk per ton of your silage. This article details the adjustments necessary to minimize energy while maximizing productivity and forage quality....

  10. 15. INSIDE THEATER PROPER. GROUND FLOOR, UNDER BALCONY, AT REAR ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    15. INSIDE THEATER PROPER. GROUND FLOOR, UNDER BALCONY, AT REAR OF SEATING AREA (SOUTH END) LOOKING EAST. VIEW OF DECORATIVE CEILING COVE. - Granada Theatre, 6425-6441 North Sheridan Road, Chicago, Cook County, IL

  11. The Proper Name as Starting Point for Basic Reading Skills

    ERIC Educational Resources Information Center

    Both-de Vries, Anna C.; Bus, Adriana G.

    2010-01-01

    Does alphabetic-phonetic writing start with the proper name and how does the name affect reading and writing skills? Sixty 4- to 5 1/2-year-old children from middle SES families with Dutch as their first language wrote their proper name and named letters. For each child we created unique sets of words with and without the child's first letter of…

  12. Quest for absolute zero in the presence of external noise

    NASA Astrophysics Data System (ADS)

    Torrontegui, E.; Kosloff, R.

    2013-09-01

    A reciprocating quantum refrigerator is analyzed with the intention to study the limitations imposed by external noise. In particular we focus on the behavior of the refrigerator when it approaches the absolute zero. The cooling cycle is based on the Otto cycle with a working medium constituted by an ensemble of noninteracting harmonic oscillators. The compression and expansion segments are generated by changing an external parameter in the Hamiltonian. In this case the force constant of the harmonic oscillators mω2 is modified from an initial to a final value. As a result, the kinetic and potential energy of the system do not commute causing frictional losses. By proper choice of scheduling function ω(t) frictionless solutions can be obtained in the noiseless case. We examine the performance of a refrigerator subject to noise. By expanding from the adiabatic limit we find that the external noise, Gaussian phase, and amplitude noises reduce the amount of heat that can be extracted but nevertheless the zero temperature can be approached.

  13. Cosmic backgrounds of relic gravitons and their absolute normalization

    NASA Astrophysics Data System (ADS)

    Giovannini, Massimo

    2014-11-01

    Provided the consistency relations are not violated, the recent BICEP2 observations pin down the absolute normalization, the spectral slope and the maximal frequency of the cosmic graviton background produced during inflation. The properly normalized spectra are hereby computed from the lowest frequencies (of the order of the present Hubble rate) up to the highest frequency range in the GHz region. Deviations from the conventional paradigm cannot be excluded and are examined by allowing for different physical possibilities including, in particular, a running of the tensor spectral index, an explicit breaking of the consistency relations and a spike in the high-frequency tail of the spectrum coming either from a post-inflationary phase dominated by a stiff fluid or from the contribution of waterfall fields in a hybrid inflationary context. The direct determinations of the tensor to scalar ratio at low frequencies, if confirmed by the forthcoming observations, will also affect and constrain the high-frequency uncertainties. The limits on the cosmic graviton backgrounds coming from wide-band interferometers (such as LIGO/Virgo, LISA and BBO/DECIGO) together with a more accurate scrutiny of the tensor B-mode polarization at low frequencies will set direct bounds on the post-inflationary evolution and on other unconventional completions of the standard lore.

  14. Foundations for proper-time relativistic quantum theory

    NASA Astrophysics Data System (ADS)

    Gill, Tepper L.; Morris, Trey; Kurtz, Stewart K.

    2015-05-01

    This paper is a progress report on the foundations for the canonical proper-time approach to relativistic quantum theory. We first review the the standard square-root equation of relativistic quantum theory, followed by a review of the Dirac equation, providing new insights into the physical properties of both. We then introduce the canonical proper-time theory. For completeness, we give a brief outline of the canonical proper-time approach to electrodynamics and mechanics, and then introduce the canonical proper-time approach to relativistic quantum theory. This theory leads to three new relativistic wave equations. In each case, the canonical generator of proper-time translations is strictly positive definite, so that it represents a particle. We show that the canonical proper-time extension of the Dirac equation for Hydrogen gives results that are consistently closer to the experimental data, when compared to the Dirac equation. However, these results are not sufficient to account for either the Lamb shift or the anomalous magnetic moment.

  15. Self-Motion Perception and Motion Sickness

    NASA Technical Reports Server (NTRS)

    Fox, Robert A.

    1991-01-01

    Motion sickness typically is considered a bothersome artifact of exposure to passive motion in vehicles of conveyance. This condition seldom has significant impact on the health of individuals because it is of brief duration, it usually can be prevented by simply avoiding the eliciting condition and, when the conditions that produce it are unavoidable, sickness dissipates with continued exposure. The studies conducted examined several aspects of motion sickness in animal models. A principle objective of these studies was to investigate the neuroanatomy that is important in motion sickness with the objectives of examining both the utility of putative models and defining neural mechanisms that are important in motion sickness.

  16. MODELING MULTI-WAVELENGTH STELLAR ASTROMETRY. II. DETERMINING ABSOLUTE INCLINATIONS, GRAVITY-DARKENING COEFFICIENTS, AND SPOT PARAMETERS OF SINGLE STARS WITH SIM LITE

    SciTech Connect

    Coughlin, Jeffrey L.; Harrison, Thomas E.; Gelino, Dawn M.

    2010-11-10

    We present a novel technique to determine the absolute inclination of single stars using multi-wavelength submilliarcsecond astrometry. The technique exploits the effect of gravity darkening, which causes a wavelength-dependent astrometric displacement parallel to a star's projected rotation axis. We find that this effect is clearly detectable using SIM Lite for various giant stars and rapid rotators, and present detailed models for multiple systems using the REFLUX code. We also explore the multi-wavelength astrometric reflex motion induced by spots on single stars. We find that it should be possible to determine spot size, relative temperature, and some positional information for both giant and nearby main-sequence stars utilizing multi-wavelength SIM Lite data. These data will be extremely useful in stellar and exoplanet astrophysics, as well as supporting the primary SIM Lite mission through proper multi-wavelength calibration of the giant star astrometric reference frame, and reduction of noise introduced by starspots when searching for extrasolar planets.

  17. Development of a cost-effective PC-based motion control system

    SciTech Connect

    Hollar, D.L.

    1998-01-01

    A cost-effective PC-based motion control system was developed and evaluated for use on a laser welding system. The motion system is capable of X-Y simultaneous contouring and provides a rotary axis of motion also. The system motion paths can be specified in either Relative or Absolute motion. The PC controls all of the laser power supply and shutter I/O operations. All of the motion programming and operator interfacing is via the Windows {reg_sign}95 operating system.

  18. Clock time is absolute and universal

    NASA Astrophysics Data System (ADS)

    Shen, Xinhang

    2015-09-01

    A critical error is found in the Special Theory of Relativity (STR): mixing up the concepts of the STR abstract time of a reference frame and the displayed time of a physical clock, which leads to use the properties of the abstract time to predict time dilation on physical clocks and all other physical processes. Actually, a clock can never directly measure the abstract time, but can only record the result of a physical process during a period of the abstract time such as the number of cycles of oscillation which is the multiplication of the abstract time and the frequency of oscillation. After Lorentz Transformation, the abstract time of a reference frame expands by a factor gamma, but the frequency of a clock decreases by the same factor gamma, and the resulting multiplication i.e. the displayed time of a moving clock remains unchanged. That is, the displayed time of any physical clock is an invariant of Lorentz Transformation. The Lorentz invariance of the displayed times of clocks can further prove within the framework of STR our earth based standard physical time is absolute, universal and independent of inertial reference frames as confirmed by both the physical fact of the universal synchronization of clocks on the GPS satellites and clocks on the earth, and the theoretical existence of the absolute and universal Galilean time in STR which has proved that time dilation and space contraction are pure illusions of STR. The existence of the absolute and universal time in STR has directly denied that the reference frame dependent abstract time of STR is the physical time, and therefore, STR is wrong and all its predictions can never happen in the physical world.

  19. Achieving Climate Change Absolute Accuracy in Orbit

    NASA Technical Reports Server (NTRS)

    Wielicki, Bruce A.; Young, D. F.; Mlynczak, M. G.; Thome, K. J; Leroy, S.; Corliss, J.; Anderson, J. G.; Ao, C. O.; Bantges, R.; Best, F.; Bowman, K.; Brindley, H.; Butler, J. J.; Collins, W.; Dykema, J. A.; Doelling, D. R.; Feldman, D. R.; Fox, N.; Huang, X.; Holz, R.; Huang, Y.; Jennings, D.; Jin, Z.; Johnson, D. G.; Jucks, K.; Kato, S.; Kratz, D. P.; Liu, X.; Lukashin, C.; Mannucci, A. J.; Phojanamongkolkij, N.; Roithmayr, C. M.; Sandford, S.; Taylor, P. C.; Xiong, X.

    2013-01-01

    The Climate Absolute Radiance and Refractivity Observatory (CLARREO) mission will provide a calibration laboratory in orbit for the purpose of accurately measuring and attributing climate change. CLARREO measurements establish new climate change benchmarks with high absolute radiometric accuracy and high statistical confidence across a wide range of essential climate variables. CLARREO's inherently high absolute accuracy will be verified and traceable on orbit to Système Internationale (SI) units. The benchmarks established by CLARREO will be critical for assessing changes in the Earth system and climate model predictive capabilities for decades into the future as society works to meet the challenge of optimizing strategies for mitigating and adapting to climate change. The CLARREO benchmarks are derived from measurements of the Earth's thermal infrared spectrum (5-50 micron), the spectrum of solar radiation reflected by the Earth and its atmosphere (320-2300 nm), and radio occultation refractivity from which accurate temperature profiles are derived. The mission has the ability to provide new spectral fingerprints of climate change, as well as to provide the first orbiting radiometer with accuracy sufficient to serve as the reference transfer standard for other space sensors, in essence serving as a "NIST [National Institute of Standards and Technology] in orbit." CLARREO will greatly improve the accuracy and relevance of a wide range of space-borne instruments for decadal climate change. Finally, CLARREO has developed new metrics and methods for determining the accuracy requirements of climate observations for a wide range of climate variables and uncertainty sources. These methods should be useful for improving our understanding of observing requirements for most climate change observations.

  20. An absolute radius scale for Saturn's rings

    NASA Technical Reports Server (NTRS)

    Nicholson, Philip D.; Cooke, Maren L.; Pelton, Emily

    1990-01-01

    Radio and stellar occultation observations of Saturn's rings made by the Voyager spacecraft are discussed. The data reveal systematic discrepancies of almost 10 km in some parts of the rings, limiting some of the investigations. A revised solution for Saturn's rotation pole has been proposed which removes the discrepancies between the stellar and radio occultation profiles. Corrections to previously published radii vary from -2 to -10 km for the radio occultation, and +5 to -6 km for the stellar occultation. An examination of spiral density waves in the outer A Ring supports that the revised absolute radii are in error by no more than 2 km.