Science.gov

Sample records for ab-type rr lyrae

  1. Synthetic RR Lyrae velocity curves

    SciTech Connect

    Liu, Tianxing Boston Univ., MA )

    1991-02-01

    An amplitude correlation between the pulsation velocity curves and visual light curves of ab-type RR Lyrae stars is derived from a large number of RR Lyrae that have high-precision radial-velocity and photometric data. Based on the determined AVp, AV ralation, a synthetic radial-velocity curve for a typical ab-type RR Lyrae star is constructed. This would be of particular use in determining the systemic velocities of RR Lyrae. 17 refs.

  2. Characteristics of bright ab-type RR Lyrae stars from the ASAS and WASP surveys

    NASA Astrophysics Data System (ADS)

    Skarka, M.

    2014-12-01

    In this article, we present results based on high-density, high-precision Wide-Angle Search for Planets (WASP) light curves supplemented with lower-precision photometry from the All-Sky Automated Survey (ASAS) for 268 RR Lyrae stars (176 regular, 92 Blazhko). Light curves were Fourier-decomposed and coefficients from WASP were transformed to the ASAS standard using 24 common stars. Coefficients were then compared with similar data from Galactic globular clusters, the Galactic bulge and the Large and Small Magellanic Clouds (LMC and SMC). Using Fourier coefficients, we also calculated physical parameters via standard equations from the literature. We confirmed the results of previous authors, including lower amplitudes and longer rise times for Blazhko stars. It was found that in the R31 versus R21 plot the location of a star depends mainly on its metallicity and that Blazhko stars prefer a different location from modulation-free stars. Field and globular cluster RR Lyrae variables have a different φ21 and φ31 from stars in the LMC, SMC and Galactic bulge. Although there are some weak indications that Blazhko stars could tend towards a slightly lower metallicity and shorter periods, no convincing proof was found. The most interesting highlight is the identification of a very recently proposed new group of metal-rich RR Lyrae type stars. These low-luminosity, metal-strong variables, comprising both Blazhko and regular stars, have shorter periods and about 180 K higher temperature at constant (B - V)0 than the rest of the stars in the sample.

  3. Fourier analysis of non-Blazhko ab-type RR Lyrae stars observed with the Kepler space telescope

    NASA Astrophysics Data System (ADS)

    Nemec, J. M.; Smolec, R.; Benkő, J. M.; Moskalik, P.; Kolenberg, K.; Szabó, R.; Kurtz, D. W.; Bryson, S.; Guggenberger, E.; Chadid, M.; Jeon, Y.-B.; Kunder, A.; Layden, A. C.; Kinemuchi, K.; Kiss, L. L.; Poretti, E.; Christensen-Dalsgaard, J.; Kjeldsen, H.; Caldwell, D.; Ripepi, V.; Derekas, A.; Nuspl, J.; Mullally, F.; Thompson, S. E.; Borucki, W. J.

    2011-10-01

    Nineteen of the ˜40 RR Lyr stars in the Kepler field have been identified as candidate non-Blazhko (or unmodulated) stars. In this paper we present the results of Fourier decomposition of the time-series photometry of these stars acquired during the first 417 d of operation (Q0-Q5) of the Kepler telescope. Fourier parameters based on ˜18 400 long-cadence observations per star (and ˜150 000 short-cadence observations for FN Lyr and for AW Dra) are derived. None of the stars shows the recently discovered 'period-doubling' effect seen in Blazhko variables; however, KIC 7021124 has been found to pulsate simultaneously in the fundamental and second overtone modes with a period ratio P2/P0˜ 0.593 05 and is similar to the double-mode star V350 Lyr. Period change rates are derived from O - C diagrams spanning, in some cases, over 100 years; these are compared with high-precision periods derived from the Kepler data alone. Extant Fourier correlations by Kovács, Jurcsik et al. (with minor transformations from the V to the Kp passband) have been used to derive underlying physical characteristics for all the stars. This procedure seems to be validated through comparisons of the Kepler variables with Galactic and Large Magellanic Cloud (LMC) RR Lyr stars. The most metal-poor star in the sample is NR Lyr, with [Fe/H] =-2.3 dex; and the four most metal-rich stars have [Fe/H] ranging from -0.6 to +0.1 dex. Pulsational luminosities and masses are found to be systematically smaller than L and ? values derived from stellar evolution models, and are favoured over the evolutionary values when periods are computed with the Warsaw linear hydrodynamics code. Finally, the Fourier parameters are compared with theoretical values derived using the Warsaw non-linear convective pulsation code.

  4. NONLINEAR ASTEROSEISMOLOGY OF RR LYRAE

    SciTech Connect

    Molnar, L.; Kollath, Z.; Szabo, R.; Bryson, S.; Mullally, F.; Thompson, S. E.; Kolenberg, K.

    2012-09-20

    The observations of the Kepler Space Telescope revealed that fundamental-mode RR Lyrae stars may show various radial overtones. The presence of multiple radial modes may allow us to conduct nonlinear asteroseismology: comparison of mode amplitudes and frequency shifts between observations and models. Here we report the detection of three radial modes in the star RR Lyr, the eponym of the class, using the Kepler short cadence data: besides the fundamental mode, both the first and the ninth overtones can be derived from the data set. RR Lyrae shows period doubling, but switches occasionally to a state where a pattern of six pulsation cycles repeats instead of two. We found hydrodynamic models that show the same three modes and the period-six state, allowing for comparison with the observations.

  5. The RR Lyrae variable population in the Phoenix dwarf galaxy

    SciTech Connect

    Ordoñez, Antonio J.; Sarajedini, Ata; Yang, Soung-Chul E-mail: ata@astro.ufl.edu

    2014-05-10

    We present the first detailed study of the RR Lyrae variable population in the Local Group dSph/dIrr transition galaxy, Phoenix, using previously obtained HST/WFPC2 observations of the galaxy. We utilize template light curve fitting routines to obtain best fit light curves for RR Lyrae variables in Phoenix. Our technique has identified 78 highly probable RR Lyrae stars (54 ab-type; 24 c-type) with about 40 additional candidates. We find mean periods for the two populations of (P {sub ab}) = 0.60 ± 0.03 days and (P{sub c} ) = 0.353 ± 0.002 days. We use the properties of these light curves to extract, among other things, a metallicity distribution function for ab-type RR Lyrae. Our analysis yields a mean metallicity of ([Fe/H]) = –1.68 ± 0.06 dex for the RRab stars. From the mean period and metallicity calculated from the ab-type RR Lyrae, we conclude that Phoenix is more likely of intermediate Oosterhoff type; however the morphology of the Bailey diagram for Phoenix RR Lyraes appears similar to that of an Oosterhoff type I system. Using the RRab stars, we also study the chemical enrichment law for Phoenix. We find that our metallicity distribution is reasonably well fitted by a closed-box model. The parameters of this model are compatible with the findings of Hidalgo et al., further supporting the idea that Phoenix appears to have been chemically enriched as a closed-box-like system during the early stage of its formation and evolution.

  6. RR Lyrae stars as standard candles

    NASA Technical Reports Server (NTRS)

    Lee, Young-Wook

    1992-01-01

    Recent developments in our understanding of RR Lyrae variables are discussed, with special emphasis on their role as distance indicators. The dependence of RR Lyrae luminosity on metallicity and horizontal-branch (HB) morphology is now well understood with many pieces of supporting evidence. This allows the determination of distances to several Local Group galaxies (LMC, M31, and M33) by constructing HB population models that reproduce the observed luminosity functions of RR Lyraes in these galaxies. The new RR Lyrae distances to M31 and M33 are some 15-37 percent larger than those adopted by de Vaucouleurs (1986) and by Aaronson et al. (1986), while they are in reasonable agreements with the recent results based on multicolor CCD photometry of classical Cepheids. This indicates that the large value of Hubble constant (90-100 km/s/Mpc) suggested by these authors may be due, at least in part, to the errors in distances to nearby calibrating galaxies.

  7. New Double-Mode RR Lyrae Variables

    NASA Astrophysics Data System (ADS)

    Khruslov, A. V.

    2014-11-01

    We present a new study of 28 known RR Lyrae variable stars. We analyzed all observations available for these stars in the Catalina Surveys, LINEAR, Northern Sky Variability Survey, and SuperWASP online public archives using the period-search software developed by Dr. V.P. Goranskij for Windows environment. According to these data, the stars are double-mode RR Lyrae variables, pulsating in the first-overtone and fundamental modes.

  8. FIRST KEPLER RESULTS ON RR LYRAE STARS

    SciTech Connect

    Kolenberg, K.; Guggenberger, E.; Szabo, R.; Benko, J. M.; Derekas, A.; Kollath, Z.; Nuspl, J.; Kurtz, D. W.; Gilliland, R. L.; Christensen-Dalsgaard, J.; Kjeldsen, H.; Brown, T. M.; Chadid, M.; Criscienzo, M. Di; Kinemuchi, K.; Kunder, A.; Kopacki, G.; Moskalik, P.; Nemec, J. M.; Silvotti, R.

    2010-04-20

    We present the first results of our analyses of selected RR Lyrae stars for which data have been obtained by the Kepler Mission. As expected, we find a significant fraction of the RRab stars to show the Blazhko effect, a still unexplained phenomenon that manifests itself as periodic amplitude and phase modulations of the light curve, on timescales of typically tens to hundreds of days. The long time span of the Kepler Mission of 3.5 yr and the unprecedentedly high precision of its data provide a unique opportunity for the study of RR Lyrae stars. Using data of a modulated star observed in the first roll as a showcase, we discuss the data, our analyses, findings, and their implications for our understanding of RR Lyrae stars and the Blazhko effect. With at least 40% of the RR Lyrae stars in our sample showing modulation, we confirm the high incidence rate that was only found in recent high-precision studies. Moreover, we report the occurrence of additional frequencies, beyond the main pulsation mode and its modulation components. Their half-integer ratio to the main frequency is reminiscent of a period doubling effect caused by resonances, observed for the first time in RR Lyrae stars.

  9. First Kepler Results on RR Lyrae Stars

    NASA Astrophysics Data System (ADS)

    Kolenberg, K.; Szabó, R.; Kurtz, D. W.; Gilliland, R. L.; Christensen-Dalsgaard, J.; Kjeldsen, H.; Brown, T. M.; Benkő, J. M.; Chadid, M.; Derekas, A.; Di Criscienzo, M.; Guggenberger, E.; Kinemuchi, K.; Kunder, A.; Kolláth, Z.; Kopacki, G.; Moskalik, P.; Nemec, J. M.; Nuspl, J.; Silvotti, R.; Suran, M. D.; Borucki, W. J.; Koch, D.; Jenkins, J. M.

    2010-04-01

    We present the first results of our analyses of selected RR Lyrae stars for which data have been obtained by the Kepler Mission. As expected, we find a significant fraction of the RRab stars to show the Blazhko effect, a still unexplained phenomenon that manifests itself as periodic amplitude and phase modulations of the light curve, on timescales of typically tens to hundreds of days. The long time span of the Kepler Mission of 3.5 yr and the unprecedentedly high precision of its data provide a unique opportunity for the study of RR Lyrae stars. Using data of a modulated star observed in the first roll as a showcase, we discuss the data, our analyses, findings, and their implications for our understanding of RR Lyrae stars and the Blazhko effect. With at least 40% of the RR Lyrae stars in our sample showing modulation, we confirm the high incidence rate that was only found in recent high-precision studies. Moreover, we report the occurrence of additional frequencies, beyond the main pulsation mode and its modulation components. Their half-integer ratio to the main frequency is reminiscent of a period doubling effect caused by resonances, observed for the first time in RR Lyrae stars.

  10. RR Lyrae stars in the MACHO database

    SciTech Connect

    Minniti, D.; Alcock, C; Alves, D. R.; Axelrod, T. S.; Bennett, D. P.; Cook, K. H.; Marshall, S. L.; Pratt, M. R.

    1996-10-01

    The MACHO Project has catalogued {approximately} 8000 RR Lyrae stars in the Large Magellanic Cloud, {approximately} 180 in the Galactic bulge, and {approximately} 50 in the Sgr dwarf galaxy. These variables are excellent distance indicators, and are used as tools to study the structure of the Large Magellanic Cloud and the bulge. The large datasets also probe uncommon pulsation modes. A number of double-mode RR Lyrae stars (RRd) are found in the Large Magellanic Cloud sample. These stars provide important clues for understanding the formation and evolution of the inner Galaxy, the Large Magellanic Cloud and the Sgr dwarf galaxy. A large number of second overtone pulsators (RRe) are found in the LMC and bulge. Finally, the RR Lyrae belonging to the Sgr dwarf yield an accurate distance to this galaxy. Their presence also alerts us of the very interesting possibility of distant sources for bulge microlensing effects. 49 refs., 7 figs., 1 tab.

  11. The magnificent past of RR Lyrae variables

    NASA Astrophysics Data System (ADS)

    Poretti, E.; Le Borgne, J.-F.; Klotz, A.; Audejean, M.; Hirosawa, K.

    2016-05-01

    We briefly review the results obtained by using the times of maximum brightness of RR Lyrae variables. They cover more than 120 years and have been used to study the evolutionary changes of the pulsational periods, the different shapes of the Blazhko effect among Galactic RRab stars, and the interplay between pulsational and Blazhko periods in the eponym of the class, RR Lyr. The data are stored in the GEOS database, continuously fed by contributions from professional and amateur astronomers.

  12. Analysis of RR Lyrae stars of the Northern Sky Variability Survey

    NASA Astrophysics Data System (ADS)

    Kinemuchi, Karen

    RR Lyrae variable stars are important astronomical objects for the investigation of the structure and evolution of the Milky Way Galaxy. These pulsating stars are known to be found in old populations in our Galaxy and have the useful feature that we can readily derive distances from them. With a large survey of the Galaxy, the RR Lyrae stars can be used to map Galactic structures. The Northern Sky Variability Survey (NSVS), whose data was obtained through the Robotic Optical Transient Search Experiment (ROTSE-I) telescope, provides an opportunity to study RR Lyraes found near the Sun. The RR Lyrae stars can be detected up to 7-9 kiloparsecs from the Sun and can probe the inner halo and thick disk component of the Galaxy. This survey is an excellent complement to other Galactic surveys of the bulge and halo components. We have found that almost 90% of the RR Lyraes in the NSVS survey are not included in the General Catalog of Variable Stars (Kholopov 1985). Our sample of RR Lyraes consists of approximately 1430 ab-type RR Lyrae and 375 c-type RR Lyrae candidates. We have determined the periods and amplitudes, and have derived phased light curves for these stars. Metallicity ([Fe/H]) of these stars was derived from the photometric data using empirical methods developed by Jurcsik & Kovacs (1996) and Sandage (2004). To derive distances, we made use of an M V -[Fe/H] relation from Cacciari & Clementini (2003). We have also found that our sample of c-type RR Lyraes close to the plane is contaminated by other types of short period variable stars. RR Lyrae stars of both Oosterhoff I and II groups are present in the field population of RR Lyraes, but we find that the Oosterhoff I is dominant. A metal-rich group of stars was found in our ab-type RR Lyrae sample. These metal-rich stars were identified as belonging to the thick disk population. This metal-rich group was used to find the scale height of the thick disk. The result is approximately 0.4 kpc, which is lower than

  13. RR Lyrae stars in the Gaia era

    NASA Astrophysics Data System (ADS)

    Clementini, G.

    2016-05-01

    Gaia, the European Space Agency spacecraft successfully launched on 19 December 2013, entered into nominal science operations on 18 July 2014 after a few months of commissioning, and has been scanning the sky to a faint limit of G=20.7 mag since then. Gaia is expected to observe more than a hundred thousand RR Lyrae stars in the Galactic halo and bulge (most of which will be new discoveries), and to provide parallax measurements with about 10 muas uncertainty for those brighter than < V > ˜12-13 mag. Status and activities of the spacecraft since launch are briefly reviewed with emphasis on preliminary results obtained for RR Lyrae stars observed in the Large Magellanic Cloud during the first 28 days of science operations spent in Ecliptic Pole scanning mode and in light of the first Gaia data release which is scheduled for summer 2016.

  14. Period Determination of RR Lyrae Stars

    NASA Astrophysics Data System (ADS)

    Stellingwerf, Robert F.

    2011-08-01

    The classic problem of detection of periodic signals in the presence of noise becomes much more challenging if the observation times are themselves periodic, contain large gaps, or consist of data from several different instruments. For RR Lyrae light curves the additional attribute of highly non-sinusoidal variation adds another dimension. This memo discusses and contrasts Discrete Fourier, Periodogram, and Phase Dispersion Minimization (PDM) analysis techniques. A new version of the PDM technique is described with tests and applications.

  15. Nonlinear Convective Models of RR Lyrae Stars

    NASA Astrophysics Data System (ADS)

    Feuchtinger, M.; Dorfi, E. A.

    The nonlinear behavior of RR Lyrae pulsations is investigated using a state-of-the-art numerical technique solving the full time-dependent system of radiation hydrodynamics. Grey radiative transfer is included by a variable Eddington-factor method and we use the time-dependent turbulent convection model according to Kuhfuss (1986, A&A 160, 116) in the version of Wuchterl (1995, Comp. Phys. Comm. 89, 19). OPAL opacities extended by the Alexander molecule opacities at temperatures below 6000 K and an equation of state according to Wuchterl (1990, A&A 238, 83) close the system. The resulting nonlinear system is discretized on an adaptive mesh developed by Dorfi & Drury (1987, J. Comp. Phys. 69, 175), which is important to provide the necessary spatial resolution in critical regions like ionization zones and shock waves. Additionally, we employ a second order advection scheme, a time centered temporal discretizaton and an artificial tensor viscosity in order to treat discontinuities. We compute fundamental as well first overtone models of RR Lyrae stars for a grid of stellar parameters both with and without convective energy transport in order to give a detailed picture of the pulsation-convection interaction. In order to investigate the influence of the different features of the convection model calculations with and without overshooting, turbulent pressure and turbulent viscosity are performed and compared with each other. A standard Fourier decomposition is used to confront the resulting light and radial velocity variations with recent observations and we show that the well known RR Lyrae phase discrepancy problem (Simon 1985, ApJ 299, 723) can be resolved with these stellar pulsation computations.

  16. The RR Lyrae stars: New perspectives

    SciTech Connect

    McNamara, D. H.; Barnes, J. E-mail: jonathan.barnes@slcc.edu

    2014-02-01

    We demonstrate that the Oosterhoff II (Oo II) RR Lyrae ab variables are hotter by ∼270 K, at the same period, than Oo I variables. Or, at the same ((B) – (V)){sub 0} value the Oo II variables have larger radii than Oo I variables. This accounts for the reason Oo II variables are brighter (0.12-0.20 mag) than Oo I variables. The dependence of the light amplitude of RR Lyrae variables on temperature is independent of Oo type. This makes it possible to derive an accurate set of equations to relate intrinsic (B – V){sub 0} color indices to light amplitudes, which in turn can be used to determine the interstellar reddening (E (B – V)). With just a few variables (∼5), it is possible to determine the E (B – V) to an accuracy of <0.01 mag in the absence of systematic photometric errors. We discuss the errors introduced in color excess determinations by including the Blazhko stars in a solution. A comparison of color excess values of 23 globular clusters and two regions of the Large Magellanic Cloud (LMC), determined with the aid of our newly developed equations, are found to compare favorably (∼0.01 mag) with color excess values found in the literature. Four new Oo III variables, some found in metal-poor clusters, are discussed. An analysis of the galactic-field variables indicates the majority are Oo I and Oo II variables, but a few short-period (log P < –0.36) metal-strong variables, so far not found in galactic globular clusters are evidently ∼0.30 mag fainter than Oo I variables. Oo III variables may also be present in the field. We conclude that the RR Lyrae ab variables are primarily restricted to four sequences or groups. If we assume that the Oo I variables' mean absolute magnitude is Mv = 0.61, the mean absolute magnitudes of the other three sequences are: short-period variables Mv ∼ 0.89 mag, Oo II Mv ∼ 0.43 mag, and Oo III Mv ∼ 0.29 mag. The Oo I fundamental RR Lyrae ab red edge (FRE) and fundamental blue edge (FBE) occur at approximately

  17. New RR Lyrae variables in binary systems

    NASA Astrophysics Data System (ADS)

    Hajdu, G.; Catelan, M.; Jurcsik, J.; Dékány, I.; Drake, A. J.; Marquette, J.-B.

    2015-04-01

    Despite their importance, very few RR Lyrae (RRL) stars have been known to reside in binary systems. We report on a search for binary RRL in the OGLE-III Galactic bulge data. Our approach consists in the search for evidence of the light-travel time effect in so-called observed minus calculated (O-C) diagrams. Analysis of 1952 well-observed fundamental-mode RRL in the OGLE-III data revealed an initial sample of 29 candidates. We used the recently released OGLE-IV data to extend the baselines up to 17 yr, leading to a final sample of 12 firm binary candidates. We provide O-C diagrams and binary parameters for this final sample, and also discuss the properties of eight additional candidate binaries whose parameters cannot be firmly determined at present. We also estimate that ≳ 4 per cent of the RRL reside in binary systems.

  18. RR Lyrae Stars: Cosmic Lighthouses With a Twist

    NASA Astrophysics Data System (ADS)

    Kolenberg, K.

    2012-06-01

    Since their discovery over a century ago, RR Lyrae stars have proven to be valuable objects for the entire field of astrophysics. They are used as standard candles and witnesses of galactic evolution. Though the pulsations that cause their light variations are dominated by relatively “simple” radial modes, some aspects of RR Lyrae pulsation remain enigmatic. Besides the visual, photographic, and photometric observations of these stars that span several decades, spectroscopic data provide an in-depth view on the pulsations. In the past decade, particularly since the launch of the satellite missions with asteroseismology as part of their program (for example, MOST, CoRoT, and Kepler), several findings have helped us better understand the structure and pulsations of RR Lyrae stars. Nevertheless, ground-based observations and long-term monitoring of RR Lyrae stars, as done by the AAVSO members, remain of utmost importance.

  19. Helium abundance effects on RR Lyrae pulsation properties

    NASA Astrophysics Data System (ADS)

    Marconi, M.; Coppola, G.; Bono, G.; Braga, V.; Pietrinferni, A.

    2016-05-01

    A new set of nonlinear convective pulsation models of RR Lyrae stars has been computed varying both the metallicity and the helium content. To constrain the helium dependence of pulsation observables we adopted, for each metal content, at least three different helium abundances. We provide for the first time a homogeneous evolutionary and pulsation framework covering the entire range of cluster and field variables. The implications for the use of RR Lyrae as stellar population tracers and distance indicators are briefly discussed.

  20. Charting Unexplored Dwarf Galaxy Territory with RR Lyrae

    NASA Astrophysics Data System (ADS)

    Baker, Mariah; Willman, Beth

    2015-11-01

    Observational biases against finding Milky Way (MW) dwarf galaxies at low Galactic latitudes (b ≲ 20°) and at low surface brightnesses ({μ }{{V,0}} ≳ 29 mag arcsec{}-2) currently limit our understanding of the faintest limits of the galaxy luminosity function. This paper is a proof-of-concept that groups of two or more RR Lyrae stars could reveal MW dwarf galaxies at d > 50 kpc in these unmined regions of parameter space, with only modest contamination from interloper groups when large halo structures are excluded. For example, a friends-of-friends (FOF) search with a 2D linking length of 500 pc could reveal dwarf galaxies more luminous than {M}{{V}} = -3.2 mag and with surface brightnesses as faint as 31 mag arcsec{}-2 (or even fainter, depending on RR Lyrae specific frequency). Although existing public RR Lyrae catalogs are highly incomplete at d > 50 kpc and/or include <1% of the MW halo’s volume, a FOF search reveals two known dwarfs (Boötes I and Sextans) and two dwarf candidate groups possibly worthy of follow-up. PanSTARRS 1 (PS1) may catalog RR Lyrae to 100 kpc (in the absence of Galactic extinction) which would include up to ˜15% of predicted MW dwarf galaxies. Groups of PS1 RR Lyrae should therefore reveal very low surface brightness and low Galactic latitude dwarfs within its footprint, if they exist. With sensitivity to RR Lyrae to d ≳ 600 kpc, LSST is the only planned survey that will be both wide-field and deep enough to use RR Lyrae to definitively measure the MW’s dwarf galaxy census to extremely low surface brightnesses, and through the Galactic plane.

  1. RR Lyrae stars in eclipsing systems -- historical candidates

    NASA Astrophysics Data System (ADS)

    Liška, J.; Skarka, M.; Hájková, P.; Auer, R. F.

    2016-03-01

    Discovery of binary systems among RR Lyrae stars belongs to challenges of present astronomy. So far, none of classical RR Lyrae stars was clearly confirmed, that it is a part of an eclipsing system. From this reason we studied two RR Lyrae stars, VX Her and RW Ari, in which changes assigned to eclipses were detected in sixties and seventies of the 20th century. In this paper our preliminary results based on analysis of new photometric measurements are presented as well as the results from the detailed analysis of original measurements. A new possible eclipsing system, RZ Cet was identified in the archive data. Our analysis rather indicates errors in measurements and reductions of the old data than real changes for all three stars.

  2. Low-dimensional chaos in RR Lyrae models

    NASA Astrophysics Data System (ADS)

    Plachy, E.; Kolláth, Z.; Molnár, L.

    2013-08-01

    The recent precise photometric observations and successes of the modelling efforts transformed our picture of the pulsation of RR Lyrae stars. The discovery of additional frequencies and the period doubling phenomenon revealed that a significant interaction may occur between pulsational modes. The signs of irregularities were detected both in observed light curves and hydrodynamic calculations. In this paper, we present the analysis of four peculiar hydrodynamic model solutions. All four solutions were found to be chaotic. The fractal (Lyapunov) dimensions of their attractors were calculated to be ˜2.2. We also investigated possible resonances between the fundamental mode and the first overtone in the dynamical neighbourhood of these models. The most important is the 6:8 resonance that was also detected in the Kepler observations of RR Lyrae itself. These results reveal that the investigation of chaotic models is important in discovering and understanding resonances in RR Lyrae stars.

  3. RR Lyrae Stars, Metal-Poor Stars, and the Galaxy

    NASA Astrophysics Data System (ADS)

    McWilliam, Andrew

    2011-08-01

    This online book contains the proceedings of a meeting on "RR Lyrae Stars, Metal-Poor Stars, and the Galaxy" held at the Carnegie Observatories, Pasadena, California, in January 2011, to honor the 80th year of George W. Preston III. The book comprises the 5th volume of the Carnegie Observatories Astrophysics Series, and contains reviews and research articles on recent developments in the area of RR Lyrae stars, including results from the Kepler space mission. Review and research articles on metal-poor stars and Galactic structure are also included.

  4. A NEW CEMP-s RR LYRAE STAR

    SciTech Connect

    Kinman, T. D.; Beers, Timothy C.; Aoki, Wako; Brown, Warren R.

    2012-08-10

    We show that SDSS J170733.93+585059.7 (hereafter SDSS J1707+58), previously identified by Aoki and collaborators as a carbon-enhanced metal-poor star (with s-process-element enhancements, CEMP-s), on the assumption that it is a main-sequence turnoff star, is the RR Lyrae star VIII-14 identified by the Lick Astrograph Survey. Revised abundances for SDSS J1707+58 are [Fe/H] = -2.92, [C/Fe] = +2.79, and [Ba/Fe] = +2.83. It is thus one of the most metal-poor RR Lyrae stars known, and has more extreme [C/Fe] and [Ba/Fe] than the only other RR Lyrae star known to have a CEMP-s spectrum (TY Gru). Both stars are Oosterhoff II stars with prograde kinematics, in contrast to stars with [C/Fe] < + 0.7, such as KP Cyg and UY CrB, which are disk stars. Twelve other RR Lyrae stars with [C/Fe] {>=}+0.7 are presented as CEMP candidates for further study.

  5. Multidimensional hydrodynamic convection in full amplitude RR Lyrae models

    NASA Astrophysics Data System (ADS)

    Deupree, R.; Geroux, C.

    2016-05-01

    Multidimensional (both 2D and 3D) hydrodynamic calculations have been performed to compute full amplitude RR Lyrae models. The multi- dimensional nature allows convection to be treated in a more realistic way than simple 1D formulations such as the local mixing length theory. We focus on some aspects of multidimensional calculations and on the model for treating convection.

  6. Improving RR Lyrae Distance Indicators Through Instrumentation, Observation, and Calibration

    NASA Astrophysics Data System (ADS)

    Klein, Christopher Robert

    Due to technological limitations and peculiarities of Nature, classes of astronomical distance indicators are applicable only in specific distance ranges. The Cosmic Distance Ladder is the framework by which we link together distance indicators, climbing from one rung to the next, in order to measure physical distance on an absolute scale. The object of this dissertation is one category of distance indicators, called RR Lyrae pulsating variable stars, which has commanded substantial scientific study for more than a century. RR Lyrae stars are low mass (M ≈ 0.7 Msol), old (age > 1010 yr) Population II objects that are found mixed in with any stellar population of requisite age. They are unstable to radial harmonic oscillations (pulsations) because of their specific mass, metallicity content, and interior composition. It has been empirically determined, and theoretically justified, that the pulsation periods of individual RR Lyrae stars are correlated with their intrinsic luminosity; hereafter referred to as the RR Lyrae period--luminosity relation. Thus, if one can measure the period of a star (a relatively straightforward task given sufficient observations), then one can use that star as a standard candle and infer its distance. The work in this dissertation is aimed at improving our understanding of the period--luminosity relation of RR Lyrae stars, and particularly at improving the precision of RR Lyrae distance measurements. By leveraging (and advancing) new observational facilities, gathering an abundance of new classical observations, and developing new statistical methods to combine a wealth of multi-wavelength data, this goal has been accomplished. In this dissertation I describe the involved methodology and report distances to a calibration sample of 134 RR Lyrae stars with a median fractional distance error of 0.66 per cent. In the following chapters I describe the arc of this research. First, I present an instrumentation development project that

  7. RR Lyrae variables in the Andromeda group galaxies

    NASA Astrophysics Data System (ADS)

    Yang, Soung-Chul

    2011-08-01

    We present the results of an extensive survey of RR Lyrae stars in the companion galaxies (M33, NGC 147, And XI and And XIII) around the Andromeda galaxy (M31). From images taken with the Advanced Camera for Surveys (ACS) Wide Field Channel (WFC) on-board the Hubble Space Telescope (HST) through two passbands (F606W and F814W), we have identified and characterized a total of 119 RR Lyrae variables (96 RRab (RR0) and 23 RRc(RR1)) in M33. Using the properties of 83 RR Lyrae stars (65 RRab and 18 RRc) in the innermost ACS field (hereafter DISK2), we find mean periods of < Pab > = 0.553 +/- 0.008 (error1) +/- 0.05 (error2) and < Pc > = 0.325 +/- 0.008 (error1) +/- 0.05 (error2), where the 'error1' value represents the standard error of the mean and the 'error2' value is based on the error of an individual RRL period calculated from our synthetic light curve simulations. The distribution of RRab periods and the frequency of RRc stars (Nc = nc/nabc = 0.22) strongly suggest that these RR Lyraes follow the general characteristics of those in Oosterhoff type I Galactic globular clusters. The metallicities of 65 individual RRab stars are calculated from the period-amplitude-metallicity relationship, yielding a mean metallicity of < [Fe/H] > = -1.48 +/- 0.05 dex, where the uncertainty is the standard error of the mean. The VI minimum-light colors of the RRab stars are used to calculate a mean line-of-sight reddening toward the DISK2 field of < E(V -- I) > = 0.175. By adopting this line-of-sight reddening and using a relation between RR Lyrae luminosity and metallicity (MV = 0.23[ Fe/H] + 0.93), we estimate a mean distance modulus of < ( m -- M)0 > = 24.52 +/- 0.11 for M33, where the error is the quadratic sum of the uncertainties in the absolute and dereddened V magnitudes of the RRLs. We used both Thuan-Gunn g-band ground-based photometry from the literature and HST Wide Field Planetary Camera 2 (WFPC2) archival data in the F555W and F814W passbands to investigate the

  8. The Extinction Toward the Galactic Bulge from RR Lyrae Stars

    SciTech Connect

    Kunder, A; Popowski, P; Cook, K; Chaboyer, B

    2007-11-07

    The authors present mean reddenings toward 3525 RR0 Lyrae stars from the Galactic bulge fields of the MACHO Survey. These reddenings are determined using the color at minimum V-band light of the RR0 Lyrae stars themselves and are found to be in general agreement with extinction estimates at the same location obtained from other methods. Using 3256 stars located in the Galactic Bulge, they derive the selective extinction coefficient R{sub V,VR} = A{sub V}/E(V-R) = 4.2 {+-} 0.2. this value is what is expected for a standard extinction law with R{sub V,BV} = 3.1 {+-} 0.3

  9. RR Lyrae Atmospherics: Wrinkles Old and New. A Preview

    NASA Astrophysics Data System (ADS)

    Preston, George W.

    2011-01-01

    I report some results of an echelle spectroscopic survey of RR Lyrae stars begun in 2006 that I presented in my Henry Norris Lecture of 2010 January 4. Topics include (1) atmospheric velocity gradients, (2) phase-dependent envelope turbulence as it relates to Peterson's discoveries of axial rotation on the horizontal branch and to Stothers' explanation of the Blazhko effect, (3) the three apparitions of hydrogen emission during a pulsation cycle, (4) the occurrence of He I lines in emission and absorption, (5) detection of He II emission and metallic line doubling in Blazhko stars, and finally (6) speculation about what helium observations of RR Lyrae stars in omega Centauri might tell us about the putative helium populations and the horizontal branch of that strange globular cluster. This paper preserves the substance and style of remarks that accompanied the author's PowerPoint presentation of the 2009 Henry Norris Russell lecture.

  10. Estimating the Distance and Metallicity of an RR Lyrae Star

    NASA Astrophysics Data System (ADS)

    Bhattacharya, Shouvik

    2013-03-01

    Minnesota State University Moorhead has a working observatory and recently renovated named the Paul P Feder Observatory at the Buffalo River State Park in the Northwest Minnesota. The observatory is equipped with a 16'' Cassegrain reflecting telescope, an Apogee Alta CCD camera, two research grade computers and the SBIG SGS Spectrograph, which was installed in the observatory facility in fall 2012. The student researcher used the facility and made photometric and spectroscopic observations of the RR Lyrae stars. The distance of the RR Lyrae star was estimated by analyzing the photometric data, extracting information about period and measured quantify brightness from the observed science images. High resolution spectroscopy was performed on the same star and its applicability to metallicity estimation will be reported.

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

    NASA Astrophysics Data System (ADS)

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

    2016-05-01

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

  12. The distances and absolute magnitudes of RR Lyrae variable stars

    NASA Astrophysics Data System (ADS)

    Jones, Rodney Vaughn

    Complete optical and infrared photometry have been acquired for three field RR Lyrae variables: the very metal-poor RRab-type variable X Arietis, the moderately metal-rich RRab star SW Draconis, and the moderately metal-rich RRc-type star DH Pegasi. Radial velocities with typical accuracies of 1 km/sec have also been obtained for these stars nearly simultaneously with the photometry. Three versions of the Baade-Wesselink method were applied, and it was determined that only combinations involving the use of the V-K color index yielded self-consistent results, due to the occurrence of a redistribution of flux during the expansion phase of the pulsation cycle such that there is an excess of flux in the blue optical region. The study of the three program stars shows that there is no dependence of the value of (MV) of RR Lyrae stars on their metallicity, although this is not definitive due to their unclear evolutionary status. If these stars are indeed typical of RR Lyrae variables, then the results of (MV) = +0.80 + or - 0.14 mag and (Mbol) = +0.85 + or - 0.15 mag for the program stars indicate that stars of this class may be less luminous than previously thought. The results imply that metal-poor globular clusters are older than metal-rich clusters, and that the oldest globular clusters may have an age of about 23 billion years.

  13. The Chemical Compositions of Variable Field Horizontal-branch Stars: RR Lyrae Stars

    NASA Astrophysics Data System (ADS)

    For, Bi-Qing; Sneden, Christopher; Preston, George W.

    2011-12-01

    We present a detailed abundance study of 11 RR Lyrae ab-type variables: AS Vir, BS Aps, CD Vel, DT Hya, RV Oct, TY Gru, UV Oct, V1645 Sgr, WY Ant, XZ Aps, and Z Mic. High-resolution and high signal-to-noise ratio echelle spectra of these variables were obtained with the 2.5 m du Pont telescope at the Las Campanas Observatory. We obtained more than 2300 spectra, roughly 200 spectra per star, distributed more or less uniformly throughout the pulsational cycles. A new method has been developed to obtain the initial effective temperatures of our sample stars at a specific pulsational phase. We find that the abundance ratios are generally consistent with those of similar metallicity field stars in different evolutionary states and throughout the pulsational cycles for RR Lyrae stars. TY Gru remains the only n-capture enriched star among the RRab in our sample. A new relation is found between microturbulence and effective temperature among stars of the horizontal-branch population. In addition, the variation of microturbulence as a function of phase is empirically shown to be similar to the theoretical variation. Finally, we conclude that the derived T eff and log g values of our sample stars follow the general trend of a single mass evolutionary track.

  14. THE CHEMICAL COMPOSITIONS OF VARIABLE FIELD HORIZONTAL-BRANCH STARS: RR LYRAE STARS

    SciTech Connect

    For Biqing; Sneden, Christopher; Preston, George W.

    2011-12-01

    We present a detailed abundance study of 11 RR Lyrae ab-type variables: AS Vir, BS Aps, CD Vel, DT Hya, RV Oct, TY Gru, UV Oct, V1645 Sgr, WY Ant, XZ Aps, and Z Mic. High-resolution and high signal-to-noise ratio echelle spectra of these variables were obtained with the 2.5 m du Pont telescope at the Las Campanas Observatory. We obtained more than 2300 spectra, roughly 200 spectra per star, distributed more or less uniformly throughout the pulsational cycles. A new method has been developed to obtain the initial effective temperatures of our sample stars at a specific pulsational phase. We find that the abundance ratios are generally consistent with those of similar metallicity field stars in different evolutionary states and throughout the pulsational cycles for RR Lyrae stars. TY Gru remains the only n-capture enriched star among the RRab in our sample. A new relation is found between microturbulence and effective temperature among stars of the horizontal-branch population. In addition, the variation of microturbulence as a function of phase is empirically shown to be similar to the theoretical variation. Finally, we conclude that the derived T{sub eff} and log g values of our sample stars follow the general trend of a single mass evolutionary track.

  15. RR Lyrae Star Metallicities From Caby Photometry

    NASA Astrophysics Data System (ADS)

    Baird, Scott R.

    1996-11-01

    Ten RR Lyr stars have been observed at different pulsational phases with Caby photoelectric photometry to calibrate the response of this system to RR Lyr metallicity. As has been done for nonvariable stars, the data are displayed in a color-color diagram of hk vs b-y, where hk=(Ca-b)-(b-y). It is found that the system is much more sensitive to metal abundance than the Stromgren m1 index, and that the system retains good sensitivity even at the hottest phases of pulsation. The data produce lines of constant metallicity on the hk/b-y diagram which are single valued with respect to both b-y and hk. Therefore Caby photometry gives a metallicity which is independent of pulsational phase, a distinct advantage over ΔS and other techniques used to find RR Lyr abundances. This phase independence probably arises from the fact that Caby photometry is concerned largely with total absorption from the Ca K and H lines and the b - y continuum, and not the specific shapes of the hydrogen lines, which can be affected by changes in surface gravity as a function of phase in the pulsation and by emission near maximum light. The metallicity of the RRc star V7S3 Cen is determined to be -0.69±0.2 dex using the Caby technique.

  16. RADIAL VELOCITIES AND PULSATION EPHEMERIDES OF 11 FIELD RR Lyrae STARS

    SciTech Connect

    For, Bi-Qing; Sneden, Christopher; Preston, George W.

    2011-06-01

    We present new radial velocities (RVs), improved pulsation periods, and reference epochs of 11 field RR Lyrae ab-type variables: AS Vir, BS Aps, CD Vel, DT Hya, RV Oct, TY Gru, UV Oct, V1645 Sgr, WY Ant, XZ Aps, and Z Mic. This study is based on high-resolution spectra obtained with the echelle spectrograph of the 2.5 m du Pont telescope at Las Campanas Observatory. We obtained {approx}200 spectra per star (i.e., a total of {approx}2300 spectra), distributed more or less uniformly throughout their pulsation cycles. RV curves and photometric light curves phased to our new ephemerides are presented for all program stars. In a subsequent paper, we will use these spectra to derive stellar atmospheric parameters and chemical compositions throughout the pulsational cycles, based purely on spectroscopic constraints.

  17. Radial Velocities and Pulsation Ephemerides of 11 Field RR Lyrae Stars

    NASA Astrophysics Data System (ADS)

    For, Bi-Qing; Preston, George W.; Sneden, Christopher

    2011-06-01

    We present new radial velocities (RVs), improved pulsation periods, and reference epochs of 11 field RR Lyrae ab-type variables: AS Vir, BS Aps, CD Vel, DT Hya, RV Oct, TY Gru, UV Oct, V1645 Sgr, WY Ant, XZ Aps, and Z Mic. This study is based on high-resolution spectra obtained with the echelle spectrograph of the 2.5 m du Pont telescope at Las Campanas Observatory. We obtained ~200 spectra per star (i.e., a total of ~2300 spectra), distributed more or less uniformly throughout their pulsation cycles. RV curves and photometric light curves phased to our new ephemerides are presented for all program stars. In a subsequent paper, we will use these spectra to derive stellar atmospheric parameters and chemical compositions throughout the pulsational cycles, based purely on spectroscopic constraints.

  18. Verbesserte Elemente der RR-Lyrae-Sterne IQ Bootis, V651 Aurigae und BQ Lyrae

    NASA Astrophysics Data System (ADS)

    Maintz, Gisela

    2015-04-01

    CCD observations of neglected RR Lyrae stars were taken at my private observatory. IQ Boo is a RRab star with a hump in the rising branch. BQ Lyr shows a weak Blazhko effect. The elements of these stars were revised. Star Max period +- JD [d] [d] IQ Boo 2457213.4681 0.535234 0.000001 V651 Aur 2457040.4056 0.617715 0.000003 BQ Lyr 2455703.4120 0.4350488 0.0000002

  19. An Update on the Status of RR Lyrae Research - Report of the RRL2015 Meeting (October, Hungary) (Abstract)

    NASA Astrophysics Data System (ADS)

    Kolenberg, K.

    2016-06-01

    (Abstract only) In October 2015 we organized the first international meeting focused on RR Lyrae research, with the goal to discuss recent developments and future RR Lyrae plans. The Scientific rationale is the following:

  20. Emission lines and shock waves in RR Lyrae stars

    NASA Astrophysics Data System (ADS)

    Gillet, D.; Fokin, A. B.

    2014-05-01

    Context. Emission lines observed in radially pulsating stars are thought to be produced by atoms de-exciting after being excited by a shock wave that is traveling into and then compressing, heating, and accelerating the atmospheric gas. Aims: With the help of recent observations, we examine the origin of all the different types of emission lines of hydrogen and helium that appear during a pulsation cycle. Methods: To analyze the physical origin of emission lines, we used the different models of atmospheric dynamics of RR Lyrae stars that have been calculated so far. Results: In contrast to a recent explanation, we propose that the redshifted emission component of Hα, which occurs near the pulsation phase 0.3, is produced by the main shock. In this case, the emission is the natural consequence of the large extension of the expanding atmosphere. Therefore, this (weak) emission should only be observed in RR Lyrae stars for which the main shock will propagate far enough from the photosphere. It appears as a P-Cygni type profile. We estimate the shock front velocity during the shock propagation in the atmosphere and show that it decreases by 40% when the Hα emitting-shock passes from the photospheric level to the upper atmosphere. The Hα P-Cygni profile observed in long-period Cepheids also seems to be caused by the main shock wave. Although to date He II has only been detected in some Blazhko stars, a comprehensive survey of RR Lyrae stars is necessary to confirm this trend, so we can say that the most intense shocks will only be observed in Blazhko stars. Conclusions: The development of a model of atmospheric pulsation that takes the effects of 2D and 3D convection into account, seems to be a necessary step to fully quantify the effects of shock waves on the atmospheric dynamics of radially pulsating stars.

  1. THE HORIZONTAL BRANCH OF NGC 1851: CONSTRAINTS FROM ITS RR LYRAE VARIABLES

    SciTech Connect

    Kunder, Andrea; De Propris, Roberto; Walker, Alistair; Salaris, Maurizio; Cassisi, Santi; Stetson, Peter B.; Catelan, Marcio; Amigo, Pia E-mail: mcatelan@astro.puc.cl

    2013-01-01

    We use the pulsational properties of the RR Lyrae variables in the globular cluster NGC 1851 to obtain detailed constraints of the various sub-stellar populations present along its horizontal branch. On the basis of detailed synthetic horizontal branch modeling, we find that minor helium variations (Y {approx} 0.248-0.280) are able to reproduce the observed periods and amplitudes of the RR Lyrae variables, as well as the frequency of fundamental and first-overtone RR Lyrae stars. Comparison of number ratios among the blue and red horizontal branch components and the two observed subgiant branches also suggest that the RR Lyrae variables originated from the progeny of the bright subgiant branch. The RR Lyrae variables with slightly enhanced helium (Y {approx} 0.270-0.280) have longer periods at a given amplitude, as is seen with Oosterhoff II (OoII) RR Lyrae variables, whereas the RR Lyrae variables with Y {approx} 0.248-0.270 have shorter periods, exhibiting properties of Oosterhoff I (OoI) variables. This correlation does suggest that the pulsational properties of RR Lyrae stars can be very useful for tracing the various subpopulations and can provide suitable constraints on the multiple population phenomenon. It appears to be of great interest to explore whether this conclusion can be generalized to other globular clusters hosting multiple populations.

  2. A search for binary candidates among the fundamental mode RR Lyrae stars observed by Kepler

    NASA Astrophysics Data System (ADS)

    Guggenberger, Elisabeth; Steixner, Jakob

    2015-09-01

    Although roughly half of all stars are considered to be part of binary or multiple systems, there are only two confirmed cases of RR Lyrae pulsators with companions. One of them is TU Uma [1] - a classical RR Lyrae star in a very eccentric orbit - and the other is OGLE-BLG-RRLYR-02792 [2]. Considering the wealth of well-studied RR Lyrae stars, this number is astoundingly low. Having more RR Lyrae stars in binary systems at hand would be extremely valuable to get independent measurements of the masses. The data from the Kepler mission with their unprecedented precision and the long time span of about four years offer a unique possibility to systematically search for the signatures of binarity in RR Lyrae stars. Using the pulsation as a clock, we studied the variations in the timing of maximum light to hunt for possible binary systems in the sample.

  3. A Swift/UVOT NUV Study of RR Lyrae Stars in the Globular Cluster M3

    NASA Astrophysics Data System (ADS)

    Porterfield, Blair; Siegel, M.; Swift; UVOT

    2014-01-01

    We present the first results of a program to monitor RR Lyrae stars in globular clusters with the Swift Ultraviolet Optical Telescope. Although variable stars have their strongest pulsations in the UV, no comprehensive catalog of NUV light curves has ever been produced for RR Lyrae stars. We present uvm2 light curves for 124 variable star candidates in the globular cluster M3. We show that the RR Lyrae stars have strong pulsations in the NUV, with amplitudes up to three magnitudes. We show that the RR Lyrae follow period-amplitude relations in the NUV similar to those they follow in the optical. Our data hint at the existence of a period-metallicity-luminosity relationship in the UV that would make RR Lyrae even more useful standard candles.

  4. RR Lyrae Stars in the GCVS Observed by the Qatar Exoplanet Survey

    NASA Astrophysics Data System (ADS)

    Bramich, D. M.; Alsubai, K. A.; Arellano Ferro, A.; Parley, N. R.; Collier Cameron, A.; Horne, K.; Pollacco, D.; West, R. G.

    2014-05-01

    We used the light curve archive of the Qatar Exoplanet Survey to investigate the RR Lyrae variable stars listed in the GCVS. Of 588 variables studied, we reclassified 14 as eclipsing binaries, one as an RS CVn type variable, one as an irregular variable, four as classical Cepheids, and one as a type II Cepheid, while also improving their periods. We also report new RR Lyrae sub-type classifications for 65 variables and improve on the GCVS period estimates for 135 RR Lyrae variables. There are seven double-mode RR Lyrae stars in the sample for which we measured their fundamental and first overtone periods. Finally, we detected the Blazhko effect in 38 of the RR Lyrae stars for the first time and we successfully measured the Blazhko period for 26 of them.

  5. THE RR LYRAE VARIABLES AND HORIZONTAL BRANCH OF NGC 6656 (M22) {sup ,}

    SciTech Connect

    Kunder, Andrea; Walker, Alistair R.; Paredes Alvarez, Leonardo; Stetson, Peter B.; Cassisi, Santi; Layden, Andrew; Bono, Giuseppe; Catelan, Márcio; Clem, James L.; Matsunaga, Noriyuki; Salaris, Maurizio; Lee, Jae-Woo; Chaboyer, Brian E-mail: mcatelan@astro.puc.cl

    2013-11-01

    The first calibrated broadband UBVI time-series photometry is presented for the RR Lyrae variable stars in NGC 6656 (M22), with observations spanning a range of 22 years. We have also redetermined the variability types and periods for the RR Lyrae stars identified previously by photographic observations, revising the number of fundamental-mode RR Lyrae variables (RR0) to 10 and the number of first-overtone variables (RR1) to 16. The mean periods of the RR0 and RR1 variables are (P) {sub RR0} = 0.66 ± 0.02 days and (P) {sub RR1} = 0.33 ± 0.01 days, respectively, supporting an Oosterhoff II classification for the cluster. The number ratio of RR1-type to all RR-type variables is N {sub 1}/N{sub RR} = 0.61, also consistent with an Oosterhoff II designation. Both the RR Lyrae stars' minimum light colors and the blue edge of the RR Lyrae instability strip suggest E( B – – V) = 0.36 ± 0.02 mag toward M22. Regarding the HB morphology of M22, we find (B-R)/(B+V+R) = +0.97 ± 0.1 and at least one ''gap'' located in an unusual part of the blue HB, in the middle of the so-called hot HB stars.

  6. Stellar evolution and period changes in RR Lyrae stars

    NASA Technical Reports Server (NTRS)

    Lee, Young-Wook

    1991-01-01

    The observed secular period changes of RR Lyrae stars in five globular clusters have been compared with those predicted by synthetic models of the horizontal branch (HB). It is shown that most of the observed number distributions of the period change rate beta could be attributed to evolutionary effects, if the random observational error is of order + or - 0.07 days/Myr in beta as suggested by the observers. The model calculations indicate that the mean rate of period change in RR Lyrae stars in globular clusters depends sensitively on their HB type, as is the case for the period shift at a given effective temperature. The distinct bias toward positive period changes in M15 and Omega Cen is evidence that most HB stars in the Oosterhoff group II clusters pass through the instability strip from blue to red toward the end of their core helium burning phase. If confirmed by future observations, this is strong support for the Lee et al. (1990) explanation of the Sandage (1957) period-shift effect.

  7. Distances and absolute magnitudes of RR Lyrae variable stars

    SciTech Connect

    Jones, R.V.

    1987-01-01

    Complete optical and infrared photometry were acquired for three fields RR Lyrae variables: the very metal-poor RRab-type variable X Arietis, the moderately metal-rich RRab star SW Draconis, and the moderately metal-rich RRc-type star DH Pegasi. Radial velocities with typical accuracies of 1 km sec/sup -1/ were also obtained for these stars nearly simultaneously with the photometry. Three versions of the Baade-Wesselink method were applied to these stars, and it was determined that only combinations involving the use of the V-K color index yielded self-consistent results, due to the occurrence of a redistribution of flux during the expansion phase of the pulsation cycle such that there is an excess of flux int eh blue optical region. Results for the three program stars indicate that there is no dependence of the value of (M/sub V/) of RR Lyrae stars upon their metallicity, although this is not definitive due to the unknown evolutionary status of these stars. The results imply that metal-poor globular clusters are older than metal-rich clusters, and that the oldest globular clusters may have an age of about 23 billion years.

  8. Nonlinear RR Lyrae models with new Livermore opacities

    NASA Astrophysics Data System (ADS)

    Guzik, J. A.; Cox, A. N.

    Recently it was shown that a 20 percent opacity decrease in the 20,000-30,000 K region, as indicated by the new Livermore OPAL opacities, reconciles the discrepancy between pulsation and evolution masses of double-mode RR Lyrae variables. Nonlinear hydrodynamic calculations were performed for RR Lyrae models of mass 0.75 solar mass, 51 solar luminosity, and Z = 0.0001 (Osterhoff II type) including this opacity decrease. The Stellingwerf periodic relaxation method was used to converge the models to a limit cycle, and the Floquet matrix eigenvalues calculated to search for a tendency of the fundamental mode to grow from the full-amplitude overtone solution, and the overtone mode to grow from the full-amplitude fundamental solution, thereby predicting double-mode behavior. Models of Teff less than 7000 K with the opacity decrease have positive fundamental-mode growth rates in the overtone solution, in contrast to earlier results, and models with Teff less than 7000 have positive 1st overtone growth rates in the fundamental-mode behavior was not found.

  9. Nonlinear RR Lyrae models with new Livermore opacities

    NASA Astrophysics Data System (ADS)

    Guzik, J. A.; Cox, A. N.

    1993-12-01

    A. N. Cox recently showed that a 20% opacity decrease in the 20,000-30,000 K region as indicated by the new Livermore OPAL opacities reconciles the discrepancy between pulsation and evolution masses of double-mode RR Lyrae variables. Nonlinear hydrodynamic calculations were performed for RR Lyrae models of mass 0.75 solar mass, 51 solar luminosity, and Z = 0.0001 (Osterhoff II type) including this opacity decrease. The Stellingwerf periodic relaxation method was used to converge the models to a limit cycle, and the Floquet matrix eigenvalues calculated to search for a tendency of the fundamental mode to grow from the full-amplitude overtone solution, and the overtone mode to grow from the full-amplitude fundamental solution, thereby predicting double-mode behavior. Models of Teff is less than 7000 K with the opacity decrease have positive fundamental-mode growth rates in the overtone solution, in contrast to earlier results by Hodson and Cox (1982), and models with Teff is greater than 7000 have positive 1st overtone growth rates in the fundamental-mode solution, but double-mode behavior was not found.

  10. A Continued Search for CEMP RR Lyrae Stars

    NASA Astrophysics Data System (ADS)

    Reggiani, H. M.; Kennedy, C. R.; Rossi, S.; Beers, T. C.

    2014-10-01

    Among the stellar populations of the Galactic halo there is a class of stars known as carbon-enhanced metal-poor (CEMP) stars. These are metal-poor ([Fe/H] < 1.0) stars whose atmospheres exhibit large overabundances of carbon ([C/Fe] ≥ +0.7). The frequency of these stars increases with decreasing metallicity, and so by studying their abundance patterns, one can begin to uncover details of the origins of the elements. There exist a number of different classes of CEMP stars (Beers & Christlieb 2005) with specific abundance characteristics; one of them is the CEMP-s class, which exhibit evidence of s-process element enrichment, widely believed to be resultant of mass transfer from a companion low-metallicity asymptotic giant branch (AGB) star, where the production of carbon and s-process elements occurs. Recent spectroscopic observations of metal-poor RR Lyrae stars have revealed that their typical abundance patterns are consistent with very metal-poor (VMP) and extremely metal-poor (EMP) giants and dwarfs studied in the halo system of the Milky Way. Of particular interest is the recent discovery of a VMP RR Lyrae that has large overabundances of carbon and the s-process elements. In this work, we showed results obtained with WiFeS observations 2.3m Siding Spring Observatory telescope of a set of newly-identified CEMP stars that are known RR Lyr stars. We confirmed theses stars as CEMP stars (Kennedy et. al., in prep) and will, eventually, test their abundances against new stellar evolution simulations of CEMP stars.

  11. Seven new carbon-enhanced metal-poor RR Lyrae stars

    SciTech Connect

    Kennedy, Catherine R.; Stancliffe, Richard J.; Kuehn, Charles; Beers, Timothy C.; Kinman, T. D.; Placco, Vinicius M.; Reggiani, Henrique; Rossi, Silvia; Lee, Young Sun

    2014-05-20

    We report estimated carbon-abundance ratios, [C/Fe], for seven newly discovered carbon-enhanced metal-poor (CEMP) RR Lyrae stars. These are well-studied RRab stars that had previously been selected as CEMP candidates based on low-resolution spectra. For this pilot study, we observed eight of these CEMP RR Lyrae candidates with the Wide Field Spectrograph on the ANU 2.3 m telescope. Prior to this study, only two CEMP RR Lyrae stars had been discovered: TY Gru and SDSS J1707+58. We compare our abundances to new theoretical models of the evolution of low-mass stars in binary systems. These simulations evolve the secondary stars, post accretion from an asymptotic giant-branch (AGB) donor, all the way to the RR Lyrae stage. The abundances of CEMP RR Lyrae stars can be used as direct probes of the nature of the donor star, such as its mass, and the amount of material accreted onto the secondary. We find that the majority of the sample of CEMP RR Lyrae stars is consistent with AGB donor masses of around 1.5-2.0 M {sub ☉} and accretion masses of a few hundredths of a solar mass. Future high-resolution studies of these newly discovered CEMP RR Lyrae stars will help disentangle the effects of the proposed mixing processes that occur in such objects.

  12. A SEARCH FOR RR LYRAE VARIABLES IN THE CENTRAL REGION OF M54

    SciTech Connect

    Montiel, Edward J.; Mighell, Kenneth J.

    2010-11-15

    We have analyzed archival Hubble Space Telescope (HST) Wide Field Planetary Camera 2 (WFPC2) observations of the central region of the globular cluster M54. The 12 irregularly timed observations (6 F555W, 6 F814W) were reduced using the HSTphot stellar photometry package. Our statistical analysis of the HSTphot photometry yielded 50 variable stars that are likely RR Lyrae candidates. These candidates were missed by previous ground-based searches for RR Lyraes due to the extreme crowding in the core of M54. We performed two checks on our sample of RR Lyrae candidates to determine how different they were from the other variable candidates. The first test was a numerical analysis comparing the ratio of variable candidates to the total number of stars within the blue horizontal branch, the RR Lyrae region, and the red giant branch. We found ratios of 0.61%, 13%, and 1.1% in these regions, respectively. Our next test was a two-sample Kolmogorov-Smirnov (K-S) test, which allowed us to find out how different our 50 RR Lyrae candidates were from the 50 brightest other variable candidates. According to the K-S test, there is only a 0.0004% probability that these two populations are similar, indicating that our RR Lyrae candidates do indeed exhibit some real fluctuation in their brightness. We sampled the light curves of confirmed RR Lyrae light curves to simulate the HST observing conditions and found that a signature of variability in 2911 out of the 4000 (72%) generated 'stars'. We estimate that there maybe as many as 19 more RR Lyrae candidates that were undetected in the WFPC2 field of view. The presence of additional RR Lyraes has implications into the current Oosterhoff classification for the cluster.

  13. On the RR Lyrae stars in omega Centauri

    NASA Astrophysics Data System (ADS)

    Braga, V. F.; Stetson, P. B.; Bono, G.; Dall'Ora, M.; Freyhammer, L. M.; Ferraro, I.; Iannicola, G.; Lub, J.; Matsunaga, N.; Neeley, J.; Marengo, M.

    2016-05-01

    We present new optical (UBV RI) photometry of RR Lyrae (RRL) stars in omega Centauri. The images were mainly collected with ESO/Danish 1.54m telescope, plus various other 1-8m class telescopes. The data set spans an area of 20x20 arcmin across the cluster center and a time interval of 21 years. We provide new homogeneous estimates of RRL pulsation properties (periods, mean magnitudes, amplitudes, epochs) and new distance determination. Using the metal-independent V,B - I period-Wesenheit relation we find a distance modulus of 13.70+-0.01+-0.09 mag. Finally, we also provide new constraints on the metallicity distribution of RRL stars using the I-band period-luminosity- metallicity relation.

  14. The first decade of RR Lyrae space photometric observations

    NASA Astrophysics Data System (ADS)

    Molnar, L.

    2016-05-01

    Space-based photometric telescopes stirred up stellar astrophysics in the last decade, and RR Lyrae stars have not been an exception from that either. The long, quasi-continuous, high-precision data from MOST, CoRoT and Kepler revealed a wealth of new insights about this well-known variable class. One of the most surprising mysteries turned out to be the apparent omnipresence of a common additional mode in all RRd and RRc stars. Moreover, fundamental- mode stars seem to populate two distinct classes, one of which is characterized by the presence of additional modes and/or modulation, and another limited to strict single-mode pulsation. The presence of additional modes and multiple modulations in RRab stars allowed us to construct Petersen diagrams for these parameters: while the pulsation modes show clear structures according to period ratios, there seems to be no relation between the modulation periods themselves.

  15. The unique dynamical system underlying RR Lyrae pulsations

    NASA Astrophysics Data System (ADS)

    Kollath, Z.

    2016-05-01

    Hydrodynamic models of RR Lyrae pulsation display a very rich behaviour. Contrary to earlier expectations, high order resonances play a crucial role in the nonlinear dynamics representing the interacting modes. Chaotic attractors can be found at different time scales: both in the pulsation itself and in the amplitude equations shaping the possible modulation of the oscillations. Although there is no one-to-one connection between the nonlinear features found in the numerical models and the observed behaviour, the richness of the found phenomena suggests that the interaction of modes should be taken seriously in the study of the still unsolved puzzle of Blazhko effect. One of the main lessons of this complex system is that we should rethink the simple interpretation of the observed effect of resonances.

  16. The Luminosities of Type II Cepheids and RR Lyrae Variables

    NASA Astrophysics Data System (ADS)

    Feast, Michael W.

    2010-02-01

    Recent work on the luminosities of type II Cepheids (CephIIs) and RR Lyrae variables is reviewed. In the near infrared (JHK_{s}) the CephIIs in globular clusters show a narrow, linear, period-luminosity relation over their whole period range (˜ 1 to 100 days). The CephIIs in the general field of the LMC follow this relation for periods shorter than ˜ 20 days. At longer period (the region of the RV Tau stars), the LMC field stars have a significant scatter and in the mean are more luminous than the PL relation. The OGLEIII optical data for the LMC field variables show similar trends. Infrared colours of stars in the RV Tau period range show marked mean differences between three groupings; the Galactic field, the LMC field, and globular clusters. In the case of the Galactic field, at least, this may be strongly influenced by selection effects. In the period range ˜ 4 to 20 days (the W Vir range) there are stars lying above the PL relation which may be recognized by their light curves and are all likely to be binaries. The bright Galactic variable, κ Pav probably belongs to this group. There is evidence that CephIIs in the general field (LMC and Galaxy) have a wider range of masses than those in globular clusters. At present the CephII PL zero-point depends on the pulsation parallaxes of two stars. Zero-points of RR Lyrae M_{V}-[Fe/H] and K_{s}-log P relations can be obtained from trigonometrical, statistical and pulsation parallaxes. These zero-points are compared with those for CephIIs and with the classical Cepheid scale using variables of these three types in the LMC. Within the uncertainties (˜ 0.1m) the various scales are in agreement.

  17. An ancient metal-poor population in M32, and halo satellite accretion in M31, identified by RR Lyrae stars

    NASA Astrophysics Data System (ADS)

    Sarajedini, Ata; Yang, S.-C.; Monachesi, A.; Lauer, Tod R.; Trager, S. C.

    2012-09-01

    We present time series photometry of two fields near M32 using archival observations from the Advanced Camera for Surveys Wide Field Channel on-board the Hubble Space Telescope. One field is centred about 2 arcmin from M32, while the other is located 15 arcmin to the south-east of M31. The imaging covers a time baseline sufficient for the identification and characterization of a total number of 1139 RR Lyrae variables of which 821 are ab-type and 318 are c-type. In the field near M32, we find a radial gradient in the density of RR Lyraes relative to the centre of M32. This gradient is consistent with the surface brightness profile of M32, suggesting that a significant number of the RR Lyraes in this region belong to M32. This provides further confirmation that M32 contains an ancient stellar population formed around the same time as the oldest population in M31 and the Milky Way. The RR Lyrae stars in M32 exhibit a mean metal abundance of <[Fe/H]> ≈ -1.42 ± 0.02, which is ≈15 times lower than the metal abundance of the overall M32 stellar population. Moreover, the abundance of RR Lyrae stars normalized to the luminosity of M32 in the field analysed further indicates that the ancient metal-poor population in M32 represents only a very minor component of this galaxy, consistent with the 1-4.5 per cent in mass inferred from the colour-magnitude diagram analysis of Monachesi et al. We also find that the measured reddening of the RR Lyrae stars is consistent with M32 containing little or no dust. In the other field, we find unprecedented evidence for two populations of RR Lyraes in M31 as shown by two distinct sequences among the ab-type variables in the Bailey diagram. When interpreted in terms of metal abundance, one population exhibits a peak at [Fe/H] ≈ -1.3 and the other is at [Fe/H] ≈ -1.9. One possible interpretation of this result is that the more metal-rich population represents the dominant M31 halo, while the metal-poorer group could be a disrupted

  18. A helium P-Cygni profile in RR Lyrae stars?

    NASA Astrophysics Data System (ADS)

    Gillet, D.; Sefyani, F. L.; Benhida, A.; Fabas, N.; Mathias, P.; Benkhaldoun, Z.; Daassou, A.

    2016-03-01

    Context. Until 2006, helium emission lines had never been observed in RR Lyrae stars. For the first time, a pre-maximum helium emission in 11 RRab stars was observed during rising light (around the pulsation phase 0.92) and the reappearance of helium emission near maximum light (phase 0.0) in one RRab star: RV Oct. This post-maximum emission has been only observed in the He I λ5875.66 (D3) line. Its intensity is very weak, and its profile mimics a P-Cygni profile with the emission peak centered at the laboratory wavelength. The physical explanation for this unexpected line profile has not been proposed yet. Aims: Using new observations of RR Lyr, we investigate the physical origin of the presence of a P-Cygni profile in the He I λ5875.66 (D3) line. Methods: High-resolution spectra of RR Lyr, collected with a spectrograph eShel/C14 at the Oukaïmeden Observatory (Morocco) in 2013, were analyzed to understand the origin of the observed P-Cygni profile at D3. Results: When the shock intensity is moderate, helium emission cannot be produced in the shock wake, and consequently, the two consecutive helium emissions (pre- and post-maximum light emissions) are not observed. This is the most frequent case. When the shock intensity becomes high enough, a pre-maximum He I emission first occurs, which can be followed by the appearance of a P-Cygni profile if the shock intensity is still strong in the high atmosphere. The observation of a P-Cygni profile means that the shock wave is already detached from the photosphere. It is shown that the shock strongly first decelerates between the pulsation phases 0.90 and 1.04 from 130 km s-1 to 60 km s-1, probably before accelerating again to 80 km s-1 near phase 1.30. Conclusions: The presence of the P-Cygni profile seems to be a natural consequence of the large extension of the expanding atmosphere, which is induced by strong (radiative) shock waves propagating toward the high atmosphere. This kind of P-Cygni profile has already been

  19. Distance Scale Zero Points from Galactic RR Lyrae Star Parallaxes

    NASA Astrophysics Data System (ADS)

    Benedict, G. Fritz; McArthur, Barbara E.; Feast, Michael W.; Barnes, Thomas G.; Harrison, Thomas E.; Bean, Jacob L.; Menzies, John W.; Chaboyer, Brian; Fossati, Luca; Nesvacil, Nicole; Smith, Horace A.; Kolenberg, Katrien; Laney, C. D.; Kochukhov, Oleg; Nelan, Edmund P.; Shulyak, D. V.; Taylor, Denise; Freedman, Wendy L.

    2011-12-01

    We present new absolute trigonometric parallaxes and proper motions for seven Population II variable stars—five RR Lyr variables: RZ Cep, XZ Cyg, SU Dra, RR Lyr, and UV Oct; and two type 2 Cepheids: VY Pyx and κ Pav. We obtained these results with astrometric data from Fine Guidance Sensors, white-light interferometers on Hubble Space Telescope. We find absolute parallaxes in milliseconds of arc: RZ Cep, 2.12 ± 0.16 mas XZ Cyg, 1.67 ± 0.17 mas SU Dra, 1.42 ± 0.16 mas RR Lyr, 3.77 ± 0.13 mas UV Oct, 1.71 ± 0.10 mas VY Pyx, 6.44 ± 0.23 mas and κ Pav, 5.57 ± 0.28 mas an average σπ/π = 5.4%. With these parallaxes, we compute absolute magnitudes in V and K bandpasses corrected for interstellar extinction and Lutz-Kelker-Hanson bias. Using these RR Lyrae variable star absolute magnitudes, we then derive zero points for MV -[Fe/H] and MK -[Fe/H]-log P relations. The technique of reduced parallaxes corroborates these results. We employ our new results to determine distances and ages of several Galactic globular clusters and the distance of the Large Magellanic Cloud. The latter is close to that previously derived from Classical Cepheids uncorrected for any metallicity effect, indicating that any such effect is small. We also discuss the somewhat puzzling results obtained for our two type 2 Cepheids. Based on observations made with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555.

  20. DISTANCE SCALE ZERO POINTS FROM GALACTIC RR LYRAE STAR PARALLAXES

    SciTech Connect

    Benedict, G. Fritz; McArthur, Barbara E.; Barnes, Thomas G.; Feast, Michael W.; Harrison, Thomas E.; Bean, Jacob L.; Kolenberg, Katrien; Menzies, John W.; Laney, C. D.; Chaboyer, Brian; Fossati, Luca; Nesvacil, Nicole; Smith, Horace A.; Kochukhov, Oleg; Nelan, Edmund P.; Taylor, Denise; Shulyak, D. V.; Freedman, Wendy L.

    2011-12-15

    We present new absolute trigonometric parallaxes and proper motions for seven Population II variable stars-five RR Lyr variables: RZ Cep, XZ Cyg, SU Dra, RR Lyr, and UV Oct; and two type 2 Cepheids: VY Pyx and {kappa} Pav. We obtained these results with astrometric data from Fine Guidance Sensors, white-light interferometers on Hubble Space Telescope. We find absolute parallaxes in milliseconds of arc: RZ Cep, 2.12 {+-} 0.16 mas; XZ Cyg, 1.67 {+-} 0.17 mas; SU Dra, 1.42 {+-} 0.16 mas; RR Lyr, 3.77 {+-} 0.13 mas; UV Oct, 1.71 {+-} 0.10 mas; VY Pyx, 6.44 {+-} 0.23 mas; and {kappa} Pav, 5.57 {+-} 0.28 mas; an average {sigma}{sub {pi}}/{pi} = 5.4%. With these parallaxes, we compute absolute magnitudes in V and K bandpasses corrected for interstellar extinction and Lutz-Kelker-Hanson bias. Using these RR Lyrae variable star absolute magnitudes, we then derive zero points for M{sub V} -[Fe/H] and M{sub K} -[Fe/H]-log P relations. The technique of reduced parallaxes corroborates these results. We employ our new results to determine distances and ages of several Galactic globular clusters and the distance of the Large Magellanic Cloud. The latter is close to that previously derived from Classical Cepheids uncorrected for any metallicity effect, indicating that any such effect is small. We also discuss the somewhat puzzling results obtained for our two type 2 Cepheids.

  1. Double-Mode RR LYRAE (RRd) Variables and a Blended RR LYRAE Pair in the Globular Cluster M3

    NASA Astrophysics Data System (ADS)

    Corwin, T. M.; Carney, B. W.

    1997-12-01

    Light curves are presented for the M3 variables V4, V68, V79, V87, V99, and V166, based on 183 CCD B images. The data were taken in 1992 and 1993 on the Kitt Peak 0.9-m telescope. V68 and V87 have long been known as double-mode pulsators, V79 has been recently identified as a double-mode pulsator (Clement et al. 1997), and V99 and V166 are identified here as double-mode pulsators. V4 has been previously identified as a blended RR Lyrae pair. The light curve of V4 is reproduced here by the sum of two RRab light curves of slightly different periods and different amplitudes. Clement C., Hilditch, R., Kaluzny, J., and Rucinski, S. 1997, ApJ, 489L, 55.

  2. Searching for distant RR Lyrae stars using the High cadence Transient Survey

    NASA Astrophysics Data System (ADS)

    Medina T., G.; Katherina Vivas, A.; Forster, F.; Munoz, R. R.

    2016-05-01

    The High cadence Transient Survey is a deep optical campaign carried out with the Dark Energy Camera imager at the 4m telescope on Cerro Tololo, Chile, aimed at detecting early supernova explosions. However, the cadence and survey strategy are well matched for RR Lyrae detection as well, with up to 37 single-band observations. Our goal is to use the data from the survey to find distant RR Lyrae and study their connection with known or undiscovered halo substructures. In the first year of the survey, we have been able to detect new RR Lyrae stars candidates out to at least 100 kpc from the Sun, and preliminary results also show the tantalizing detection of RR Lyrae even farther away.

  3. Revised [Fe/H] and Radial Velocities for 28 Distant RR Lyrae Stars

    NASA Astrophysics Data System (ADS)

    Pier, J. R.; Saha, A.; Kinman, T. D.

    2003-10-01

    New abundances ([Fe/H] and radial velocities are given for 28 RR Lyrae stars discovered by Kinman, Mahaffey and Wirtanen (1982) and by Saha (1984). The stars were observed with the IIDS scanner on the KPNO 2.1-m telescope. The scans were calibrated by observing 18 nearby RR Lyrae stars whose [Fe/H] have been given by Suntzeff et al. (1991).

  4. Review of candidates of binary systems with an RR Lyrae component

    NASA Astrophysics Data System (ADS)

    Skarka, M.; Liska, J.; Zejda, M.; Mikulasek, Z.

    2016-05-01

    We present an overview and the current status of research on RR Lyrae stars in binary systems. In recent years the number of binary candidates has steeply increased and it was suggested that the occurrence of multiple stellar systems with an RR Lyrae component is much higher than previously thought. We discuss the probability of their detection using various observing methods, compare recent results regarding selection effects, period distribution, the proposed orbital parameters and the Blazhko effect.

  5. Database of candidates for RR Lyrae stars in binary systems - RRLyrBinCan

    NASA Astrophysics Data System (ADS)

    Liska, J.; Skarka, M.

    2016-05-01

    A new on-line database with RR Lyrae stars bound in binary systems is presented. Its purpose is to give a quick overview about known and suspected RR Lyrae stars in binaries on the basis of available literature. The first released version of the catalogue contains information about 61 double-star candidates, their orbital periods, method of detection, comments and active links to published papers.

  6. High-precision 2MASS JHK{sub s} light curves and other data for RR Lyrae star SDSS J015450 + 001501: Strong constraints for nonlinear pulsation models

    SciTech Connect

    Szabó, Róbert; Ivezić, Željko; Kiss, László L.; Kolláth, Zoltán; Jones, Lynne; Becker, Andrew C.; Davenport, James R. A.; Sesar, Branimir; Cutri, Roc M.

    2014-01-01

    We present and discuss an extensive data set for the non-Blazhko ab-type RR Lyrae star SDSS J015450+001501, including optical Sloan Digital Sky Survey ugriz light curves and spectroscopic data, LINEAR and Catalina Sky Survey unfiltered optical light curves, and infrared Two Micron All Sky Survey (2MASS) JHK{sub s} and Wide-field Infrared Survey Explorer W1 and W2 light curves. Most notable is that light curves obtained by 2MASS include close to 9000 photometric measures collected over 3.3 yr and provide an exceedingly precise view of near-infrared variability. These data demonstrate that static atmosphere models are insufficient to explain multiband photometric light-curve behavior and present strong constraints for nonlinear pulsation models for RR Lyrae stars. It is a challenge to modelers to produce theoretical light curves that can explain data presented here, which we make publicly available.

  7. The chemical compositions of RR Lyrae type c variable stars

    SciTech Connect

    Govea, Jose; Gomez, Thomas; Sneden, Christopher; Preston, George W. E-mail: chris@verdi.as.utexas.edu

    2014-02-20

    We present a detailed chemical abundance study of eight RR Lyrae variable stars of subclass c (RRc). The target RRc stars chosen for study exhibit 'Blazhko-effect' period and amplitude modulations to their pulsational cycles. Data for this study were gathered with the echelle spectrograph of the 100 inch du Pont telescope at Las Campanas Observatory. Spectra were obtained throughout each star's pulsation cycle. Atmospheric parameters—effective temperature, surface gravity, microturbulent velocity, and metallicity—were derived at multiple phase points. We found metallicities and element abundance ratios to be constant within observational uncertainties over the pulsational cycles of all stars. Moreover, the α-element and Fe-group abundance ratios with respect to iron are consistent with other horizontal-branch members (RRab, blue and red non-variables). Finally, we have used the [Fe/H] values of these eight RRc stars to anchor the metallicity estimates of a large-sample RRc snapshot spectroscopic study being conducted with the same telescope and instrument combination employed here.

  8. La Silla QUEST RR Lyrae Star Survey: Region I

    NASA Astrophysics Data System (ADS)

    Zinn, R.; Horowitz, B.; Vivas, A. K.; Baltay, C.; Ellman, N.; Hadjiyska, E.; Rabinowitz, D.; Miller, L.

    2014-01-01

    A search for RR Lyrae stars (RRLSs) in ~840 deg2 of the sky in right ascension 150°-210° and declination -10° to + 10° yielded 1013 type ab and 359 type c RRLS. This sample is used to study the density profile of the Galactic halo, halo substructures, and the Oosterhoff type of the halo over distances (d ⊙) from ~5 to ~80 kpc. The halo is flattened toward the Galactic plane, and its density profile steepens in slope at galactocentric distances greater than ~25 kpc. The RRLS in the stellar stream from the Sagittarius dwarf spheroidal (dSph) galaxy match well the model of Law & Majewski for the stars that were stripped 1.3-3.2 Gyr ago, but not for the ones stripped 3.2-5.0 Gyr ago. Over densities are found at the locations of the Virgo Overdensity and the Virgo Stellar Stream. Within 1° of 1220-1, which Jerjen et al. identify as a halo substructure at d ⊙ ~ 24 kpc, there are four RRLS that are possibly members. Away from substructures, the RRLS are a mixture of Oosterhoff types I and II, but mostly OoI (~73%). The accretion of galaxies resembling in RRLS content the most massive Milky Way satellites (LMC, SMC, For, Sgr) may explain this preponderance of OoI. Six new RRLS and three new anomalous Cepheids were found in the Sextans dSph galaxy.

  9. ON THE BLAZHKO EFFECT IN RR LYRAE STARS

    SciTech Connect

    Buchler, J. Robert; Kollath, Zoltan E-mail: kollath@konkoly.hu

    2011-04-10

    The Blazhko effect is a long-term, generally irregular modulation of the light curves that occurs in a sizeable number of RR Lyrae stars. The physical origin of the effect has been a puzzle ever since its discovery over a hundred years ago. We build here upon the recent observational and theoretical work of Szabo et al. on RRab stars who found with hydrodynamical simulations that the fundamental pulsation mode can get destabilized by a 9:2 resonant interaction with the 9th overtone. Alternating pulsation cycles arise, although these remain periodic, i.e., not modulated as in the observations. Here we use the amplitude equation formalism to study this nonlinear, resonant interaction between the two modes. We show that not only does the fundamental pulsation mode break up into a period-two cycle through the nonlinear, resonant interaction with the overtone, but that the amplitudes are modulated, and that in a broad range of parameters the modulations are irregular as in the observations. This irregular behavior is in fact chaotic and arises from a strange attractor in the dynamics.

  10. PERIOD CHANGE SIMILARITIES AMONG THE RR LYRAE VARIABLES IN OOSTERHOFF I AND OOSTERHOFF II GLOBULAR SYSTEMS

    SciTech Connect

    Kunder, Andrea; Walker, Alistair; De Propris, Roberto; Stetson, Peter B.; Bono, Giuseppe; Di Cecco, Alessandra; Nemec, James M.; Monelli, Matteo; Cassisi, Santi; Andreuzzi, Gloria; Dall'Ora, Massimo; Zoccali, Manuela

    2011-01-15

    We present period change rates (dP/dt) for 42 RR Lyrae variables in the globular cluster IC 4499. Despite clear evidence of these period increases or decreases, the observed period change rates are an order of magnitude larger than predicted from theoretical models of this cluster. We find that there is a preference for increasing periods, a phenomenon observed in most RR Lyrae stars in Milky Way globular clusters. The period change rates as a function of position in the period-amplitude plane are used to examine possible evolutionary effects in OoI clusters, OoII clusters, field RR Lyrae stars, and the mixed-population cluster {omega} Centauri. It is found that there is no correlation between the period change rate and the typical definition of Oosterhoff groups. If the RR Lyrae period changes correspond with evolutionary effects, this would be in contrast to the hypothesis that RR Lyrae variables in OoII systems are evolved horizontal-branch stars that spent their zero-age horizontal-branch phase on the blue side of the instability strip. This may suggest that age may not be the primary explanation for the Oosterhoff types.

  11. The effect of Livermore OPAL opacities on the evolutionary masses of RR Lyrae stars

    NASA Technical Reports Server (NTRS)

    Yi, Sukyoung; Lee, Young-Wook; Demarque, Pierre

    1993-01-01

    We have investigated the effect of the new Livermore OPAL opacities on the evolution of horizontal-branch (HB) stars. This work was motivated by the recent stellar pulsation calculations using the new Livermore opacities, which suggest that the masses of double-mode RR Lyrae stars are 0.1-0.2 solar mass larger than those based on earlier opacities. Unlike the pulsation calculations, we find that the effect of opacity change on the evolution of HB stars is not significant. In particular, the effect of the mean masses of RR Lyrae stars is very small, showing a decrease of only 0.01-0.02 solar mass compared to the models based on old Cox-Stewart opacities. Consequently, with the new Livermore OPAL opacities, both the stellar pulsation and evolution models now predict approximately the same masses for the RR Lyrae stars. Our evolutionary models suggest that the mean masses of the RR Lyrae stars are about 0.76 and about 0.71 solar mass for M15 (Oosterhoff group II) and M3 (group I), respectively. If (alpha/Fe) = 0.4, these values are decreased by about 0.03 solar mass. Variations of the mean masses of RR Lyrae stars with HB morphology and metallicity are also presented.

  12. La Silla quest RR Lyrae star survey: Region I

    SciTech Connect

    Zinn, R.; Miller, L.; Horowitz, B.; Baltay, C.; Ellman, N.; Hadjiyska, E.; Rabinowitz, D.; Vivas, A. K.

    2014-01-20

    A search for RR Lyrae stars (RRLSs) in ∼840 deg{sup 2} of the sky in right ascension 150°-210° and declination –10° to + 10° yielded 1013 type ab and 359 type c RRLS. This sample is used to study the density profile of the Galactic halo, halo substructures, and the Oosterhoff type of the halo over distances (d {sub ☉}) from ∼5 to ∼80 kpc. The halo is flattened toward the Galactic plane, and its density profile steepens in slope at galactocentric distances greater than ∼25 kpc. The RRLS in the stellar stream from the Sagittarius dwarf spheroidal (dSph) galaxy match well the model of Law and Majewski for the stars that were stripped 1.3-3.2 Gyr ago, but not for the ones stripped 3.2-5.0 Gyr ago. Over densities are found at the locations of the Virgo Overdensity and the Virgo Stellar Stream. Within 1° of 1220-1, which Jerjen et al. identify as a halo substructure at d {sub ☉} ∼ 24 kpc, there are four RRLS that are possibly members. Away from substructures, the RRLS are a mixture of Oosterhoff types I and II, but mostly OoI (∼73%). The accretion of galaxies resembling in RRLS content the most massive Milky Way satellites (LMC, SMC, For, Sgr) may explain this preponderance of OoI. Six new RRLS and three new anomalous Cepheids were found in the Sextans dSph galaxy.

  13. Ursa Minor dSph galaxy: Updated census of RR Lyrae stars

    NASA Astrophysics Data System (ADS)

    Kinemuchi, K.; Grabowski, K.; Kuehn, C.; Nemec, J.

    2016-05-01

    We present our observations and photometric results of the Ursa Minor dwarf spheroidal galaxy (UMi dSph). Observations were taken at the Apache Point Observatory 0.5m ARCSAT telescope in 2014. We identify previously known RR Lyrae stars in the field of view, and also catalog other variable star candidates for which tentative classifications are provided. We have performed a period search for the known and new variable stars. Our ultimate goal is to create an updated catalog of variable stars in the UMi dSph and to compare the RR Lyrae stellar characteristics to other RR Lyrae stars found in Local Group dSph galaxies. The comparisons can give us insights to the near-field cosmology of the Local Group.

  14. RR Lyrae stars and color-magnitude diagram of the globular cluster NGC 6388

    NASA Technical Reports Server (NTRS)

    Silbermann, N. A.; Smith, Horace A.; Bolte, Michael; Hazen, Martha L.

    1994-01-01

    We present new V, B-V, and V, V-R color-magnitude diagrams for the bulge globular cluster NGC 6388. These diagrams indicate that NGC 6388 is a metal-rich globular cluster with color-magnitude morphology similar to that of 47 Tucanae. We have conducted a search for new variable stars close to NGC 6388, finding three new RR Lyrae stars. The membership of these and previously discovered RR Lyrae stars near NGC 6388 is discussed. There is reason for believing that some of these variables are nonmembers. Others, however, may belong to the cluster and may be similar to the RR Lyrae star V9 in 47 Tuc.

  15. Determining a mid-infrared period-luminosity relation for Galactic globular cluster RR Lyrae stars

    NASA Astrophysics Data System (ADS)

    Neeley, J.; Marengo, M.; Bono, G.; Braga, V.; Dall'Ora, M.; CRRP Team

    2016-05-01

    We present new RR Lyrae variable period-luminosity (P-L) relations at mid-infrared wavelengths. Accurate photometry was obtained for 37 RR Lyrae variables in the globular cluster M4 (NGC 6121) using the Infrared Array Camera onboard the Spitzer Space Telescope. We obtained a very tight MIR P-L relation with 0.056 mag dispersion and 0.007 mag zero point dispersion. The P-L relation was calibrated by five Galactic RR Lyrae stars with parallaxes from HST. The resulting band averaged distance modulus for M4 is 11.399 +- 0.007(statistical) +- 0.080(systematic) +- 0.015(calibration) +- 0.020(extinction).

  16. VizieR Online Data Catalog: Mid-infrared study of RR Lyrae stars (Gavrilchenko+, 2014)

    NASA Astrophysics Data System (ADS)

    Gavrilchenko, T.; Klein, C. R.; Bloom, J. S.; Richards, J. W.

    2015-02-01

    The first goal was to find a large sample of WISE-observed RR Lyrae stars. A data base of previously identified RR Lyrae stars was created, combining information from General Catalogue of Variable Stars (GCVS), All Sky Automated Survey (ASAS), SIMBAD, VizieR, and individual papers. For many of the sources in this data base the only available data were the coordinates and RR Lyrae classification. When provided, information about the period, distance, subclass, and magnitude for several different wavebands was also stored. If a single source appeared in multiple surveys or papers, information from all relevant surveys was included, with markers indicating contradicting measurements between surveys. The resulting data base contains about 17000 sources, of which about 5000 sources have documented V-band periods. (3 data files).

  17. VizieR Online Data Catalog: RR Lyrae in SDSS Stripe 82 (Suveges+, 2012)

    NASA Astrophysics Data System (ADS)

    Suveges, M.; Sesar, B.; Varadi, M.; Mowlavi, N.; Becker, A. C.; Ivezic, Z.; Beck, M.; Nienartowicz, K.; Rimoldini, L.; Dubath, P.; Bartholdi, P.; Eyer, L.

    2013-05-01

    We propose a robust principal component analysis framework for the exploitation of multiband photometric measurements in large surveys. Period search results are improved using the time-series of the first principal component due to its optimized signal-to-noise ratio. The presence of correlated excess variations in the multivariate time-series enables the detection of weaker variability. Furthermore, the direction of the largest variance differs for certain types of variable stars. This can be used as an efficient attribute for classification. The application of the method to a subsample of Sloan Digital Sky Survey Stripe 82 data yielded 132 high-amplitude delta Scuti variables. We also found 129 new RR Lyrae variables, complementary to the catalogue of Sesar et al., extending the halo area mapped by Stripe 82 RR Lyrae stars towards the Galactic bulge. The sample also comprises 25 multiperiodic or Blazhko RR Lyrae stars. (8 data files).

  18. RR Lyrae stars in omega Centauri: Near-IR properties and period-luminosity relations

    NASA Astrophysics Data System (ADS)

    Navarrete, C.; Catelan, M.; Contreras Ramos, R.; Gran, F.; Alonso-Garcia, J.

    2016-05-01

    Omega Centauri contains a rich harvest of variable stars. Here we report on a deep, wide-field, near-infrared (IR) variability survey for this cluster, carried out using ESO's 4.1m VISTA telescope. Our time-series data includes more than 180 RR Lyrae light curves in both J and Ks, allowing us to derive an unprecedented homogeneous and complete near-IR catalog of RR Lyrae in the field of omega Cen. Near-IR period-luminosity relations are derived and used to determine an updated (pulsational) distance modulus for the cluster.

  19. Detailed chemical abundances of distant RR Lyrae stars in the Virgo Stellar Stream

    NASA Astrophysics Data System (ADS)

    Duffau, S.; Sbordone, L.; Vivas, A. K.; Hansen, C. J.; Zoccali, M.; Catelan, M.; Minniti, D.; Grebel, E. K.

    2016-05-01

    We present the first detailed chemical abundances for distant RR Lyrae stars members of the Virgo Stellar Stream (VSS), derived from X- Shooter medium-resolution spectra. Sixteen elements from carbon to barium have been measured in six VSS RR Lyrae stars, sampling all main nucleosynthetic channels. For the first time we will be able to compare in detail the chemical evolution of the VSS progenitor with those of Local Group dwarf spheroidal galaxies (LG dSph) as well as the one of the smooth halo.

  20. TRACING THE ORPHAN STREAM TO 55 kpc WITH RR LYRAE STARS

    SciTech Connect

    Sesar, Branimir; Cohen, Judith G.; Bellm, Eric C.; Levitan, David; Tang, Sumin; Waszczak, Adam; Kulkarni, Shrinivas R.; Prince, Thomas A.; Grillmair, Carl J.; Laher, Russ R.; Surace, Jason A.; Bhalerao, Varun B.; Ofek, Eran O.

    2013-10-10

    We report positions, velocities, and metallicities of 50 ab-type RR Lyrae (RRab) stars observed in the vicinity of the Orphan stellar stream. Using about 30 RRab stars classified as being likely members of the Orphan stream, we study the metallicity and the spatial extent of the stream. We find that RRab stars in the Orphan stream have a wide range of metallicities, from –1.5 dex to –2.7 dex. The average metallicity of the stream is –2.1 dex, identical to the value obtained by Newberg et al. using blue horizontal branch stars. We find that the most distant parts of the stream (40-50 kpc from the Sun) are about 0.3 dex more metal-poor than the closer parts (within ∼30 kpc), suggesting a possible metallicity gradient along the stream's length. We have extended the previous studies and have mapped the stream up to 55 kpc from the Sun. Even after a careful search, we did not identify any more distant RRab stars that could plausibly be members of the Orphan stream. If confirmed with other tracers, this result would indicate a detection of the end of the leading arm of the stream. We have compared the distances of Orphan stream RRab stars with the best-fit orbits obtained by Newberg et al. We find that model 6 of Newberg et al. cannot explain the distances of the most remote Orphan stream RRab stars, and conclude that the best fit to distances of Orphan stream RRab stars and to the local circular velocity is provided by potentials where the total mass of the Galaxy within 60 kpc is M{sub 60} ∼ 2.7 × 10{sup 11} M{sub ☉}, or about 60% of the mass found by previous studies. More extensive modeling that would consider non-spherical potentials and the possibility of misalignment between the stream and the orbit is highly encouraged.

  1. Exploring the Sagittarius Stream With SEKBO Survey RR Lyrae Stars

    NASA Astrophysics Data System (ADS)

    Prior, Sayuri L.; Da Costa, G. S.; Keller, Stefan C.

    2009-10-01

    A sample of RR Lyrae (RRL) variables from the Southern Edgeworth-Kuiper Belt Object survey in regions overlapping the expected position of debris from the interaction of the Sagittarius (Sgr) dwarf galaxy with the Milky Way (R.A. ~ 20 and 21.5 hr distance = 16-21 kpc) has been followed up spectroscopically and photometrically. The 21 photometrically confirmed type ab RRLs in this region have lang[Fe/H]rang = -1.79 ± 0.08 on our system, consistent with the abundances found for RRLs in a different portion of the Sgr tidal debris stream. The distribution of velocities in the Galactic standard of rest frame (V GSR) of the 26 RRLs in the region is not consistent with a smooth halo population. Upon comparison with the Sgr disruption models of Law et al., a prominent group of five stars having highly negative radial velocities (V GSR ~-175 km s-1) is consistent with predictions for old trailing debris when the Galactic halo potential is modeled as oblate. In contrast, the prolate model does not predict any significant number of Sgr stars at the locations of the observed sample. The observations also require that the recent trailing debris stream has a broader spread perpendicular to the Sgr plane than predicted by the models. We have also investigated the possible association of the Virgo Stellar Stream (VSS) with Sgr debris by comparing radial velocities for RRLs in the region with the same models, finding similarities in the velocity-position trends. As suggested by our earlier work, the stars in the VSS region with large negative V GSR values are likely to be old leading Sgr debris, but we find that while old trailing Sgr debris may well make a contribution at positive V GSR values, it is unlikely to fully account for the VSS feature. Overall we find that further modeling is needed, as trailing arm data generally favor oblate models while leading arm data favor prolate models, with no single potential fitting all the observed data.

  2. EXPLORING THE SAGITTARIUS STREAM WITH SEKBO SURVEY RR LYRAE STARS

    SciTech Connect

    Prior, Sayuri L.; Da Costa, G. S.; Keller, Stefan C.

    2009-10-20

    A sample of RR Lyrae (RRL) variables from the Southern Edgeworth-Kuiper Belt Object survey in regions overlapping the expected position of debris from the interaction of the Sagittarius (Sgr) dwarf galaxy with the Milky Way (R.A. approx 20 and 21.5 hr; distance = 16-21 kpc) has been followed up spectroscopically and photometrically. The 21 photometrically confirmed type ab RRLs in this region have ([Fe/H]) = -1.79 +- 0.08 on our system, consistent with the abundances found for RRLs in a different portion of the Sgr tidal debris stream. The distribution of velocities in the Galactic standard of rest frame (V {sub GSR}) of the 26 RRLs in the region is not consistent with a smooth halo population. Upon comparison with the Sgr disruption models of Law et al., a prominent group of five stars having highly negative radial velocities (V {sub GSR} approx-175 km s{sup -1}) is consistent with predictions for old trailing debris when the Galactic halo potential is modeled as oblate. In contrast, the prolate model does not predict any significant number of Sgr stars at the locations of the observed sample. The observations also require that the recent trailing debris stream has a broader spread perpendicular to the Sgr plane than predicted by the models. We have also investigated the possible association of the Virgo Stellar Stream (VSS) with Sgr debris by comparing radial velocities for RRLs in the region with the same models, finding similarities in the velocity-position trends. As suggested by our earlier work, the stars in the VSS region with large negative V {sub GSR} values are likely to be old leading Sgr debris, but we find that while old trailing Sgr debris may well make a contribution at positive V {sub GSR} values, it is unlikely to fully account for the VSS feature. Overall we find that further modeling is needed, as trailing arm data generally favor oblate models while leading arm data favor prolate models, with no single potential fitting all the observed data.

  3. Period changes of 7 bright RR Lyrae variables included in the BAV standard program.

    NASA Astrophysics Data System (ADS)

    Wunder, E.

    1995-11-01

    On the basis of 1578 times of maxima historical and present period changes of the RR Lyrae stars SW And, SW Aqr, AA Aql, X Ari, RS Boo, RR Cet and XZ Cyg are analysed. In tables the period jumps and the quadratic terms of the elements are quantified and timed; elements are given to describe the historical O-C-curves; instant elements are listed to support nowadays observations.

  4. A new Phi_31-period-metallicity relation for RR Lyrae stars

    NASA Astrophysics Data System (ADS)

    Martinez-Vazquez, C. E.; Monelli, M.; Bono, G.; Stetson, P. B.; Gallart, C.; Bernard, E. J.; Fiorentino, G.; Dall'Ora, M.

    2016-05-01

    We present a new calibration of the 31-period-metallicity relation based on cluster instead of field RR Lyrae stars. The novel approach relies on mean Fourier decomposition parameters of their optical light curves, mean periods and metal abundances rooted on a solid metallicity scale. The key advantage when compared with similar relations in the literature is that individual cluster samples cover a broad range in periods, and therefore the opportunity to fully characterize, at fixed metal content, their pulsational behaviour. To accomplish this goal, we used data for seven globular clusters hosting at least 20 RR Lyrae stars and covering a broad range in metallicity (from -2.3 to -1.1 dex). To further extend the metallicity range, we also included field RR Lyrae stars with a good sampling of the light curve (ASAS, Catalina), and for which iron measurements based on high-resolution spectra are available. We applied the new calibration to 167 fundamental RR Lyrae in the Sculptor dSph and we found a considerable spread in metallicity, thus confirming the fast early chemical evolution of this galaxy (Martinez-Vazquez et al. 2015).

  5. The Swift UVOT Stars Survey. II. RR Lyrae Stars in M3 and M15

    NASA Astrophysics Data System (ADS)

    Siegel, Michael H.; Porterfield, Blair L.; Balzer, Benjamin G.; Hagen, Lea M. Z.

    2015-10-01

    We present the first results of a near-ultraviolet (NUV) survey of RR Lyrae stars from the Ultraviolet Optical Telescope (UVOT) on board the Swift Gamma-ray Burst Mission. It is well-established that RR Lyrae stars have large amplitudes in the far- and near-ultraviolet. We have used UVOT’s unique wide-field NUV imaging capability to perform the first systematic NUV survey of variable stars in the Galactic globular clusters M3 and M15. We identify 280 variable stars, comprised of 275 RR Lyrae, 2 anomalous Cepheids, 1 classical Cepheid, 1 SX Phoenicis star, and 1 possible long-period or irregular variable. Only two of these are new discoveries. We compare our results to previous investigations and find excellent agreement in the periods with significantly larger amplitudes in the NUV. We map out, for the first time, an NUV Bailey diagram from globular clusters, showing the usual loci for fundamental mode RRab and first overtone RRc pulsators. We show the unique sensitivity of NUV photometry to both the temperatures and the surface gravities of RR Lyrae stars. Finally, we show evidence of an NUV period-metallicity-luminosity relationship. Future investigations will further examine the dependence of NUV pulsation parameters on metallicity and Oosterhoff classification.

  6. Physical Characteristics for the RR Lyrae Stars in the LMC clusters NGC 2210 and NGC 2257

    NASA Astrophysics Data System (ADS)

    Nemec, James M.; Walker, Alistair

    2007-08-01

    NGC 2210 and NGC 2257 are both RR Lyrae-rich globular clusters located in the eastern halo of the Large Magellanic Cloud. NGC 2257 is unique in having been monitored reasonably continuously since the early 1950's. We propose to acquire new B,V CCD photometry that will be combined with extant photographic and CCD photometry and used to derive accurate physical characteristics for the ~40 RR Lyrae stars in each cluster. Specifically, we plan: (a) to complete the job of determining pulsation periods, amplitudes, mean colors and mean magnitudes for the uncrowded RR Lyrae stars in both clusters; (b) to derive period change rates for the NGC 2210 stars (unknown at present), and to derive dP/dt values more accurate than +/-0.02 d/Myr for the NGC 2257 stars; (c) to derive accurate Fourier decomposition coefficients for all the variable stars; and (d) to use the Fourier data to derive effective temperatures, luminosities, and masses via comparison with modern theoretical models for horizontal branch stars. Our overall goal is to analyse new extensive two-color photometry in combination with existing B,V photometry to better understand the evolution of the RR Lyrae stars in these two important clusters.

  7. AL Pictoris and FR Piscium: Two Regular Blazhko RR Lyrae Stars

    NASA Astrophysics Data System (ADS)

    de Ponthière, P.; Hambsch, F.-J.; Menzies, K.; Sabo, R.

    2014-12-01

    The results presented are a continuation of observing campaigns conducted by a small group of amateur astronomers interested in the Blazhko effect of RR Lyrae stars. The goal of these observations is to confirm the RR Lyrae Blazhko effect and to detect any additional Blazhko modulation which cannot be identified from all sky survey data-mining. The Blazhko effect of the two observed stars is confirmed, but no additional Blazhko modulations have been detected. The observation of the RR Lyrae star AL Pictoris during 169 nights was conducted from San Pedro de Atacama (Chile). From the observed light curve, 49 pulsation maxima have been measured. Fourier analyses of (O-C), magnitude at maximum light (Mmax), and the complete light curve have provided a confirmation of published pulsation and Blazhko periods, 0.548622 and 34.07 days, respectively. The second multi-longitude observation campaign focused on the RR Lyrae star FR Piscium and was performed from Europe, the United States, and Chile. Fourier analyses of the light curve and of 59 measured brightness maxima have improved the accuracy of pulsation and Blazhko periods to 0.45568 and 51.31 days, respectively. For both stars, no additional Blazhko modulations have been detected.

  8. The soundtrack of RR Lyrae in omega Cen at high-frequency.

    NASA Astrophysics Data System (ADS)

    Calamida, A.; Randall, S. K.; Monelli, M.; Bono, G.; Buonanno, R.; Strampelli, G.; Catelan, M.; Van Grootel, V.; Alonso, M. L.; Stetson, P. B.; Stellingwerf, R. F.

    We present preliminary Sloan u',g'-band light curves for a sample of known RR Lyrae variables in the Galactic globular cluster omega Cen. Results are based on the partial reduction of multi-band time series photometric data collected during six consecutive nights with the visitor instrument ULTRACAM mounted on the New Technology Telescope (La Silla, ESO). This facility allowed us to simultaneously observe in three different bands (Sloan u',g',r') a field of view of ˜ 6×6 arcminutes. The telescope and the good seeing conditions allowed us to sample the light curves every 15 seconds. We ended up with a data set of ˜ 6,000 images per night per filter, for a total of more than 200,000 images of the selected field. This data set allowed us to detect different kind of variables, such as RR-Lyraes, SX Phoenicis, eclipsing binaries, semi-regulars. More importantly, we were able for the first time to sample at high-frequency cluster RR Lyraes in the u',g'-band and to show in detail the pulsation phases across the dip located along the rising branch of RR-Lyraes. Based on data collected with ULTRACAM@NTT (La Silla, ESO, PID: 087.D-0216)

  9. Lighthouses in the fog: Locating the faintest Milky Way satellites with RR Lyrae stars

    NASA Astrophysics Data System (ADS)

    Sesar, B.

    2016-05-01

    Almost every known low-luminosity Milky Way dwarf spheroidal (dSph) satellite galaxy contains at least one RR Lyrae star. Assuming that a fraction of distant (60 < dhelio < 100 kpc) Galactic halo RR Lyrae stars are members of yet to be discovered low-luminosity dSph galaxies, we perform a guided search for these low-luminosity dSph galaxies. In order to detect the presence of dSph galaxies, we combine stars selected from more than 123 sight- lines centered on RR Lyrae stars identified by the Palomar Transient Factory. We find that this method is sensitive enough to detect the presence of Segue 1- like galaxies (MV = -1.5+0.6-0.8, rh = 30 pc) even if only ~20 sightlines were occupied by such dSph galaxies. Yet, when our method is applied to the SDSS DR10 imaging catalog, no signal is detected. An application of our method to sightlines occupied by pairs of close (< 200 pc) horizontal branch stars, also did not yield a detection. Thus, we place upper limits on the number of low- luminosity dSph galaxies with half-light radii from 30 pc to 120 pc, and in the probed volume of the halo. Stronger constraints on the luminosity function may be obtained by applying our method to sightlines centered on RR Lyrae stars selected from the Pan-STARRS1 survey, and eventually, from LSST.

  10. Observing globular cluster RR Lyraes with the BYU West Mountain Observatory

    NASA Astrophysics Data System (ADS)

    Jeffery, E. J.; Joner, M. D.; Walton, R. S.

    2016-05-01

    We have utilized the 0.9-meter telescope of the Brigham Young University West Mountain Observatory to secure data on six northern hemi- sphere globular clusters. Here we present observations of RR Lyrae stars located in these clusters. We compare light curves produced using both DAOPHOT and ISIS software packages. Light curve fitting is done with FITLC.

  11. Anomalous Double-Mode RR Lyrae Stars in the Magellanic Clouds

    NASA Astrophysics Data System (ADS)

    Soszyński, I.; Smolec, R.; Dziembowski, W. A.; Udalski, A.; Szymański, M. K.; Wyrzykowski, Ł.; Ulaczyk, K.; Poleski, R.; Pietrukowicz, P.; Kozłowski, S.; Skowron, D.; Skowron, J.; Mróz, P.; Pawlak, M.

    2016-08-01

    We report the discovery of a new subclass of double-mode RR Lyrae stars in the Large and Small Magellanic Clouds. The sample of 22 pulsating stars have been extracted from the latest edition of the OGLE collection of RR Lyrae variables in the Magellanic System. The stars pulsating simultaneously in the fundamental (F) and first-overtone (1O) modes have distinctly different properties than regular double-mode RR Lyrae variables (RRd stars). The P1O/PF period ratios of our anomalous RRd stars are within a range 0.725-0.738, while "classical" double-mode RR Lyrae variables have period ratios in the range 0.742-0.748. In contrast to the typical RRd stars, in the majority of the anomalous pulsators the F-mode amplitudes are higher than the 1O-mode amplitudes. The light curves associated with the F-mode in the anomalous RRd stars show different morphology than the light curves of, both, regular RRd stars and single-mode RRab stars. Most of the anomalous double-mode stars show long-term modulations of the amplitudes (Blazhko-like effect). Translating the period ratios into the abundance parameter, Z, we find for our stars Z ∈ (0.002, 0.005) - an order of magnitude higher values than typical for RR Lyrae stars. The mass range of the RRd stars inferred from the WI vs. PF diagram is (0.55 - 0.75) M⊙. These parameters cannot be accounted for with single star evolution assuming a Reimers-like mass loss. Much greater mass loss caused by interaction with other stars is postulated. We blame the peculiar pulsation properties of our stars to the parametric resonance instability of the 1O-mode to excitation of the F- and 2O-modes as with the inferred parameters of the stars 2ω1O ≈ ωF + ω2O.

  12. THE DETERMINATION OF REDDENING FROM INTRINSIC VR COLORS OF RR LYRAE STARS

    SciTech Connect

    Kunder, Andrea; Chaboyer, Brian; Layden, Andrew E-mail: Brian.Chaboyer@dartmouth.edu

    2010-02-15

    New R-band observations of 21 local field RR Lyrae variable stars are used to explore the reliability of minimum light (V - R) colors as a tool for measuring interstellar reddening. For each star, R-band intensity mean magnitudes and light amplitudes are presented. Corresponding V-band light curves from the literature are supplemented with the new photometry, and (V - R) colors at minimum light are determined for a subset of these stars as well as for other stars in the literature. Two different definitions of minimum light color are examined, one which uses a Fourier decomposition to the V and R light curves to find (V - R) at minimum V-band light, (V - R) {sup F} {sub min}, and the other which uses the average color between the phase interval 0.5-0.8, (V - R){sup {phi}}{sup (0.5-0.8)} {sub min}. From 31 stars with a wide range of metallicities and pulsation periods, the mean dereddened RR Lyrae color at minimum light is (V - R) {sup F} {sub min,0} = 0.28 {+-} 0.02 mag and (V - R){sup {phi}}{sup (0.5-0.8)} {sub min,0} = 0.27 {+-} 0.02 mag. As was found by Guldenschuh et al. using (V - I) colors, any dependence of the star's minimum light color on metallicity or pulsation amplitude is too weak to be formally detected. We find that the intrinsic (V - R) of Galactic bulge RR Lyrae stars are similar to those found by their local counterparts and hence that bulge RR0 Lyrae stars do not have anomalous colors as compared to the local RR Lyrae stars.

  13. Updated census of RR Lyrae stars in the globular cluster ω Centauri (NGC 5139)

    NASA Astrophysics Data System (ADS)

    Navarrete, C.; Contreras Ramos, R.; Catelan, M.; Clement, C. M.; Gran, F.; Alonso-García, J.; Angeloni, R.; Hempel, M.; Dékány, I.; Minniti, D.

    2015-05-01

    Aims: ω Centauri (NGC 5139) contains many variable stars of different types and, in particular, more than one hundred RR Lyrae stars. This enabled gathering a homogeneous sample (in terms of instrument, image quality, and time coverage) of high-quality near-infrared (NIR) RR Lyrae light curves by performing an extensive time-series campaign aimed at this object. We have conducted a variability survey of ω Cen in the NIR, using ESO's 4.1 m Visible and Infrared Survey Telescope for Astronomy (VISTA). This is the first paper of a series describing our results. Methods: ω Cen was observed using VIRCAM mounted on VISTA. A total of 42 epochs in J and 100 epochs in KS were obtained, distributed over a total timespan of 352 days. Point-spread function photometry was performed using DAOPHOT in the inner and DoPhot in the outer regions of the cluster. Periods of the known variable stars were improved when necessary using an ANOVA analysis. Results: We collected an unprecedented homogeneous and complete NIR catalog of RR Lyrae stars in the field of ω Cen, allowing us to study for the first time all the RR Lyrae stars associated with the cluster, except for four stars that are located far away from the cluster center. We derived membership status, subclassifications between RRab and RRc subtypes, periods, amplitudes, and mean magnitudes for all the stars in our sample. Additionally, four new RR Lyrae stars were discovered, two of which are very likely cluster members. We also discuss here the distribution of ω Cen stars in the Bailey (period-amplitude) diagram. We provide reference lines in this plane for both Oosterhoff Type I (OoI) and Oosterhoff Type II (OoII) components in J and KS. Conclusions: We clarify the status of many (candidate) RR Lyrae stars that have been reported as unclear in previous studies. This includes stars with anomalous positions in the color-magnitude diagram, uncertain periods or/and variability types, and possible field interlopers. We conclude

  14. HST/ACS Observations of RR Lyrae Stars in Six Ultra-Deep Fields of M31

    NASA Technical Reports Server (NTRS)

    Jeffery, E. J.; Smith, E.; Brown, T. M.; Sweigart, A. V.; Kalirai, J. S.; Ferguson, H. C.; Guhathakurta, P.; Renzini, A.; Rich, R. M.

    2010-01-01

    We present HST/ACS observations of RR Lyrae variable stars in six ultra deep fields of the Andromeda galaxy (M31), including parts of the halo, disk, and giant stellar stream. Past work on the RR Lyrae stars in M31 has focused on various aspects of the stellar populations that make up the galaxy s halo, including their distances and metallicities. This study builds upon this previous work by increasing the spatial coverage (something that has been lacking in previous studies) and by searching for these variable stars in constituents of the galaxy not yet explored. Besides the 55 RR Lyrae stars we found in our initial field located 11kpc from the galactic nucleus, we find additional RR Lyrae stars in four of the remaining five ultra deep fields as follows: 21 in the disk, 24 in the giant stellar stream, 3 in the halo field 21kpc from the galactic nucleus, and 5 in one of the halo fields at 35kpc. No RR Lyrae were found in the second halo field at 35kpc. The RR Lyrae populations of these fields appear to mostly be of Oosterhoff I type, although the 11kpc field appears to be intermediate or mixed. We will discuss the properties of these stars including period and reddening distributions. We calculate metallicities and distances for the stars in each of these fields using different methods and compare the results, to an extent that has not yet been done. We compare these methods not just on RR Lyrae in our M31 fields, but also on a data set of Milky Way field RR Lyrae stars.

  15. HST/ACS OBSERVATIONS OF RR LYRAE STARS IN SIX ULTRA-DEEP FIELDS OF M31

    SciTech Connect

    Jeffery, E. J.; Smith, E.; Brown, T. M.; Kalirai, J. S.; Ferguson, H. C.; Sweigart, A. V.; Rich, R. M.

    2011-05-15

    We present HST/ACS observations of RR Lyrae variable stars in six ultra-deep fields of the Andromeda galaxy (M31), including parts of the halo, disk, and giant stellar stream. Past work on the RR Lyrae stars in M31 has focused on various aspects of the stellar populations that make up the galaxy's halo, including their distances and metallicities. This study builds upon this previous work by increasing the spatial coverage (something that has been lacking in previous studies) and by searching for these variable stars in constituents of the galaxy not yet explored. Besides the 55 RR Lyrae stars we found in our initial field located 11 kpc from the galactic nucleus, we find additional RR Lyrae stars in four of the remaining five ultra-deep fields as follows: 21 in the disk, 24 in the giant stellar stream, three in the halo field 21 kpc from the galactic nucleus, and five in one of the halo fields at 35 kpc. No RR Lyrae stars were found in the second halo field at 35 kpc. The RR Lyrae populations of these fields appear to be mostly of Oosterhoff I type, although the 11 kpc field appears to be intermediate or mixed. We will discuss the properties of these stars including period and reddening distributions. We calculate metallicities and distances for the stars in each of these fields using different methods and compare the results, to an extent that has not yet been done. We compare these methods not just on RR Lyrae stars in our M31 fields, but also on a data set of Milky Way field RR Lyrae stars.

  16. Near-field cosmology with RR Lyrae variable stars: A first view of substructure in the southern sky

    NASA Astrophysics Data System (ADS)

    Duffau, S.; Vivas, A. K.; Navarrete, C.; Catelan, M.; Hajdu, G.; Torrealba, G.; Cortes, C.; Belokurov, V.; Koposov, S.; Drake, A. J.

    2016-05-01

    We present an update of a spectroscopic follow-up survey at low- resolution of a large number of RR Lyrae halo overdensity candidates found in the southern sky. The substructure candidates were identified in the RR Lyrae catalog of Torrealba et al. (2015) using Catalina Real-time Transient Survey (CRTS) data. Radial velocities and mean metallicities have been estimated for target stars in almost half of the original overdensities to assess their potential membership to coherent halo features.

  17. RR-Lyrae-type pulsations from a 0.26-solar-mass star in a binary system.

    PubMed

    Pietrzyński, G; Thompson, I B; Gieren, W; Graczyk, D; Stępień, K; Bono, G; Moroni, P G Prada; Pilecki, B; Udalski, A; Soszyński, I; Preston, G W; Nardetto, N; McWilliam, A; Roederer, I U; Górski, M; Konorski, P; Storm, J

    2012-04-01

    RR Lyrae pulsating stars have been extensively used as tracers of old stellar populations for the purpose of determining the ages of galaxies, and as tools to measure distances to nearby galaxies. There was accordingly considerable interest when the RR Lyrae star OGLE-BLG-RRLYR-02792 (referred to here as RRLYR-02792) was found to be a member of an eclipsing binary system, because the mass of the pulsator (hitherto constrained only by models) could be unambiguously determined. Here we report that RRLYR-02792 has a mass of 0.26 solar masses M[symbol see text] and therefore cannot be a classical RR Lyrae star. Using models, we find that its properties are best explained by the evolution of a close binary system that started with M[symbol see text] and 0.8M[symbol see text]stars orbiting each other with an initial period of 2.9 days. Mass exchange over 5.4 billion years produced the observed system, which is now in a very short-lived phase where the physical properties of the pulsator happen to place it in the same instability strip of the Hertzsprung-Russell diagram as that occupied by RR Lyrae stars. We estimate that only 0.2 per cent of RR Lyrae stars may be contaminated by systems similar to this one, which implies that distances measured with RR Lyrae stars should not be significantly affected by these binary interlopers. PMID:22481359

  18. RR Lyrae stars as probes of the Milky Way structure and formation

    NASA Astrophysics Data System (ADS)

    Pietrukowicz, Pawel

    2016-08-01

    RR Lyrae stars being distance indicators and tracers of old population serve as excellent probes of the structure, formation, and evolution of our Galaxy. Thousands of them are being discovered in ongoing wide-field surveys. The OGLE project conducts the Galaxy Variability Survey with the aim to detect and analyze variable stars, in particular of RRab type, toward the Galactic bulge and disk, covering a total area of 3000 deg2. Observations in these directions also allow detecting background halo variables and unique studies of their properties and distribution at distances from the Galactic Center to even 40 kpc. In this contribution, we present the first results on the spatial distribution of the observed RRab stars, their metallicity distribution, the presence of multiple populations, and relations with the old bulge. We also show the most recent results from the analysis of RR Lyrae stars of the Sgr dwarf spheroidal galaxy, including its center, the globular cluster M54.

  19. On the Sandage period shift effect among field RR Lyrae stars

    NASA Technical Reports Server (NTRS)

    Lee, Young-Wook

    1990-01-01

    The origin of the disagreement between the results of the synthetic horizontal branch (HB) model of Lee et al. (1990) and the Sandage (1990) analysis of Lub's (1977) data on a sample of field RR Lyrae stars is investigated, extending the original synthetic HB calculations of Lee et al. to all HB types over the metallicity range of the Galactic halo. It is shown that the period shifts of the RR Lyrae stars in globular clusters depend strongly on their HB type and metallicity. Results suggest that the disagreement between the slopes, Delta logP(Teff)/Delta Fe/H, obtained by Lee et al. and the ones obtained by Sandage can be explained by the fact that Lub's sample may have contained many highly evolved stars in the metallicity range of Fe/H between -2.0 and -1.6, since Lee's analysis did not include these stars.

  20. THE IMPACT OF CONTAMINATED RR LYRAE/GLOBULAR CLUSTER PHOTOMETRY ON THE DISTANCE SCALE

    SciTech Connect

    Majaess, D.; Turner, D.; Lane, D.; Gieren, W.

    2012-06-10

    RR Lyrae variables and the stellar constituents of globular clusters are employed to establish the cosmic distance scale and age of the universe. However, photometry for RR Lyrae variables in the globular clusters M3, M15, M54, M92, NGC 2419, and NGC 6441 exhibit a dependence on the clustercentric distance. For example, variables and stars positioned near the crowded high-surface brightness cores of the clusters may suffer from photometric contamination, which invariably affects a suite of inferred parameters (e.g., distance, color excess, absolute magnitude, etc.). The impetus for this study is to mitigate the propagation of systematic uncertainties by increasing awareness of the pernicious impact of contaminated and radial-dependent photometry.

  1. DISTANCE TO THE SAGITTARIUS DWARF GALAXY USING MACHO PROJECT RR LYRAE STARS

    SciTech Connect

    Kunder, Andrea; Chaboyer, Brian E-mail: brian.chaboyer@dartmouth.edu

    2009-05-15

    We derive the distance to the northern extension of the Sagittarius (Sgr) dwarf spheroidal galaxy from 203 Sgr RR0 Lyrae stars found in the MACHO database. Their distances are determined differentially with respect to 288 Galactic bulge RR0 Lyrae stars also found in the MACHO data. We find a distance modulus difference of 2.41 mag at l = 5{sup 0} and b = -8{sup 0} and that the extension of the Sgr galaxy toward the galactic plane is inclined toward us. Assuming R {sub GC} = 8 kpc, this implies the distance to these stars is (m - M){sub 0} = 16.97 {+-} 0.07 mag, which corresponds to D = 24.8 {+-} 0.8 kpc. Although this estimate is smaller than previous determinations for this galaxy and agrees with previous suggestions that Sgr's body is truly closer to us, this estimate is larger than studies at comparable galactic latitudes.

  2. On the Sandage period shift effect among field RR Lyrae stars

    SciTech Connect

    Lee, Y. Victoria Univ. )

    1990-11-01

    The origin of the disagreement between the results of the synthetic horizontal branch (HB) model of Lee et al. (1990) and the Sandage (1990) analysis of Lub's (1977) data on a sample of field RR Lyrae stars is investigated, extending the original synthetic HB calculations of Lee et al. to all HB types over the metallicity range of the Galactic halo. It is shown that the period shifts of the RR Lyrae stars in globular clusters depend strongly on their HB type and metallicity. Results suggest that the disagreement between the slopes, Delta logP(Teff)/Delta Fe/H, obtained by Lee et al. and the ones obtained by Sandage can be explained by the fact that Lub's sample may have contained many highly evolved stars in the metallicity range of Fe/H between -2.0 and -1.6, since Lee's analysis did not include these stars. 48 refs.

  3. Changing Amplitudes: Detecting RR Lyrae Light Curve Shape Variations in the Galactic Disk and Inner Halo

    NASA Astrophysics Data System (ADS)

    De Lee, Nathan M.; Kinemuchi, K.; Pepper, J.; Rodriguez, J. E.

    2014-01-01

    In this poster we will discuss our ongoing program to use extant light curves from the Kilodegree Extremely Little Telescope (KELT) survey to find and characterize RR Lyrae (RRL) stars in the disk and inner halo of the Milky Way. RRL stars are of particular interest because they are standard candles and can be used to map out structure in the galaxy. The periods and shape of RRL light curves also contain information about their Oosterhoff type, which can probe galactic formation history, and metallicity respectively. Although there have been several large photometric surveys for RR Lyrae in the nearby galaxy (OGLE, NSVS, ASAS, and MACHO to name a few), they have each been limited in either sky coverage or number of epochs. The KELT survey represents a new generation of surveys that has many epochs over a large portion of the sky. KELT samples 60% of the sky in both northern and southern hemispheres, and has a long-time-baseline of 4-8 years with a very high cadence rate of less than 20 minutes. This translates into 4,000 to 9,000 epochs per light curve with completeness out to 3 kpc from the Sun. Recent results from both Kepler and ground based surveys results suggest that as many as 50% of RR Lyrae stars show long-term modulation of their light curve shapes (Blazhko effect). These stars combined with RRL stars that pulsate in more than one mode give a sample of objects that the KELT survey is uniquely suited to explore. This poster concentrates on a pilot project to examine RRL stars in a limited number of KELT fields. In particular, we focus on, detecting RR Lyrae, developing a light curve shape-metallicity relationship in the KELT band-pass, and some initial characterization of RRL with either amplitude-modulated or period-modulated light curves.

  4. Observations and Analysis of Three Field RR Lyrae Stars Selected Using Single-epoch SDSS Data

    NASA Astrophysics Data System (ADS)

    Powell, W. L., Jr.; Jameson, S. N.; De lee, N.; Wilhelm, R. J.

    2015-08-01

    We present the results of our Johnson B and V observations of three RR Lyrae candidate stars that we identified as likely variable stars using SDSS data. The stars were selected based upon a single epoch of photometry and spectroscopy. The stars were observed at McDonald Observatory to obtain full light curves. We present full light curves, measured periods, and amplitudes, as well as the results of our Fourier analysis of the light curves.

  5. Double-Mode Radial Pulsations among RR Lyrae Stars

    NASA Astrophysics Data System (ADS)

    Poleski, Radosław

    2014-06-01

    Double-mode RR Lyr type stars are important for studies of properties of horizontal-branch stars. In particular, two periods coupled with spectral properties give a mass estimate that is independent of evolutionary models. Here, we present 59 new Galactic double-mode RR Lyr stars found in the LINEAR survey data with the fundamental radial mode and the first overtone exited (RRd stars). These stars may be useful for constraining the mass-metallicity relation for field horizontal-branch stars. Also, new RRd stars found in the LMC by EROS-II are verified. We present the updated Petersen diagram and the distribution of the fundamental mode periods. Comments on selected variable stars from LINEAR and LMC EROS-II surveys are also presented, including very rare objects: the third known mode-switching RR Lyr and a Cepheid pulsating simultaneously in three radial modes.

  6. Period-doubling bifurcation and high-order resonances in RR Lyrae hydrodynamical models

    NASA Astrophysics Data System (ADS)

    Kolláth, Z.; Molnár, L.; Szabó, R.

    2011-06-01

    We investigated period doubling, a well-known phenomenon in dynamical systems, for the first time in RR Lyrae models. These studies provide theoretical background for the recent discovery of period doubling in some Blazhko RR Lyrae stars with the Kepler space telescope. Since period doubling has been observed only in Blazhko-modulated stars so far, the phenomenon can help in understanding the modulation as well. Utilizing the Florida-Budapest turbulent convective hydrodynamical code, we have identified the phenomenon in both radiative and convective models. A period-doubling cascade was also followed up to an eight-period solution, confirming that destabilization of the limit cycle is indeed the underlying phenomenon. Floquet stability roots were calculated to investigate the possible causes and occurrences of the phenomenon. A two-dimensional diagnostic diagram was constructed to illustrate the various resonances between the fundamental mode and the different overtones. Combining the two tools, we confirmed that the period-doubling instability is caused by a 9:2 resonance between the ninth overtone and the fundamental mode. Destabilization of the limit cycle by a resonance of a high-order mode is possible because the overtone is a strange mode. The resonance is found to be strong enough to shift the period of overtone by up to 10 per cent. Our investigations suggest that a more complex interplay of radial (and presumably non-radial) modes could happen in RR Lyrae stars that might have connections with the Blazhko effect as well.

  7. The space photometry revolution and our understanding of RR Lyrae stars

    NASA Astrophysics Data System (ADS)

    Szabó, R.; Benkő, M. J.; Paparó, M.; Chapellier, E.; Poretti, E.; Baglin, A.; Weiss, W. W.; Kolenberg, K.; Guggenberger, E.; Le Borgne, J.-F.

    2015-09-01

    The study of RR Lyrae stars has recently been invigorated thanks to the long, uninterrupted, ultra-precise time series data provided by the Kepler and CoRoT space telescopes. We give a brief overview of the new observational findings concentrating on the connection between period doubling and the Blazhko modulation, and the omnipresence of additional periodicities in all RR Lyrae subtypes, except for non-modulated RRab stars. Recent theoretical results demonstrate that if more than two modes are present in a nonlinear dynamical system such as a high-amplitude RR Lyrae star, the outcome is often an extremely intricate dynamical state. Thus, based on these discoveries, an underlying picture of complex dynamical interactions between modes is emerging which sheds new light on the century-old Blazhko-phenomenon, as well. New directions of theoretical efforts, like multidimensional hydrodynamical simulations, future space photometric missions and detailed spectroscopic investigations will pave the way towards a more complete understanding of the atmospheric and pulsation dynamics of these enigmatic touchstone objects.

  8. Probing Kinematic Substructures in the Virgo Overdensity using RR Lyrae from Recent Surveys

    NASA Astrophysics Data System (ADS)

    Farmer, John; Vivas, A. Katherina

    2015-01-01

    The Virgo Overdensity is one of the most intriguing features of the galactic halo, as it covers a large portion of the sky and seems to contain several kinematic substructures. It has been suggested that the remnants of several merger events coexist in this region. RR Lyrae stars are an excellent tracer for disentangling the different components of this overdensity, since they are excellent standard candles; by using both positions and pulsation-corrected radial velocities, we can identify distinct groups in phase space. In the last year, several surveys for RR Lyraes covering the Virgo region have become publicly available. We present analysis of ~300 spectra for ~200 stars in the Virgo overdensity region. This is a significant increase in the known sample of these stars in the region, spanning a significantly larger area of the sky than previous studies. Photometry for these data are taken primarily from the La Silla and Venezuela QUEST variability surveys with spectra provided by SDSS Data Release 10. Radial velocities for type ab RR Lyrae stars are corrected using the new set of template radial velocity curves for Balmer and metallic lines given by Sesar (2012). We combine data from QUEST, the Catalina Sky Survey, LINEAR, and spectroscopic observations from Duffau (2014) to give our full sample. A preliminary analysis reveals confirmation for several known stellar streams.

  9. The identification of RR Lyrae and δ Scutti stars from variable galaxy evolution explorer ultraviolet sources

    SciTech Connect

    Kinman, T. D.; Brown, Warren R.

    2014-12-01

    We identify the RR Lyrae and δ Scuti stars in three catalogs of Galaxy Evolution Explorer (GALEX) variable sources. The NUV amplitude of RR Lyrae stars is about twice that in V, so we find a larger percentage of low-amplitude variables than catalogs such as Abbas et al. Interestingly, the (NUV – V){sub 0} color is sensitive to metallicity and can be used to distinguish between variables of the same period but differing [Fe/H]. This color is also more sensitive to T {sub eff} than optical colors and can be used to identify the red edge of the instability gap. We find 8 δ Scuti stars, 17 RRc stars, 1 RRd star, and 84 RRab stars in the GALEX variable catalogs of Welsh et al. and Wheatley et al. We also classify 6 δ Scuti stars, 5 RRc stars, and 18 RRab stars among the 55 variable GALEX sources identified as 'stars' or RR Lyrae stars in the catalog of Gezari et al. We provide ephemerides and light curves for the 26 variables that were not previously known.

  10. An RR Lyrae family portrait: 33 stars observed in Pisces with K2-E2

    NASA Astrophysics Data System (ADS)

    Molnár, L.; Szabó, R.; Moskalik, P. A.; Nemec, J. M.; Guggenberger, E.; Smolec, R.; Poleski, R.; Plachy, E.; Kolenberg, K.; Kolláth, Z.

    2015-10-01

    A detailed analysis is presented of 33 RR Lyrae stars in Pisces observed with the Kepler space telescope over the 8.9-d long K2 Two-Wheel Concept Engineering Test. The sample includes not only fundamental-mode and first-overtone (RRab and RRc) stars but the first two double-mode (RRd) stars that Kepler detected and the only modulated first-overtone star ever observed from space so far. The precision of the extracted K2 light curves made it possible to detect low-amplitude additional modes in all subtypes. All RRd and non-modulated RRc stars show the additional mode at PX/P1 ˜ 0.61 that was detected in previous space-based photometric measurements. A periodicity longer than the fundamental mode was tentatively identified in one RRab star that might belong to a gravity mode. We determined the photometric [Fe/H] values for all fundamental-mode stars and provide the preliminary results of our efforts to fit the double-mode stars with non-linear hydrodynamic pulsation models. The results from this short test run indicate that the K2 mission will be, and has started to be, an ideal tool to expand our knowledge about RR Lyrae stars. As a by-product of the target search and analysis, we identified 165 bona fide double-mode RR Lyrae stars from the Catalina Sky Survey observations throughout the sky, 130 of which are new discoveries.

  11. The OGLE Collection of Variable Stars. Over 45 000 RR Lyrae Stars in the Magellanic System

    NASA Astrophysics Data System (ADS)

    Soszyński, I.; Udalski, A.; Szymański, M. K.; Wyrzykowski, Ł.; Ulaczyk, K.; Poleski, R.; Pietrukowicz, P.; Kozłowski, S.; Skowron, D. M.; Skowron, J.; Mróz, P.; Pawlak, M.

    2016-06-01

    We present the largest collection of RR Lyrae stars in the Magellanic System and in its foreground. The sample consists of 45 451 RR Lyr stars, of which 39 082 were detected toward the Large Magellanic Cloud and 6369 toward the Small Magellanic Cloud. We provide long-term time-series photometric measurements collected during the fourth phase of the Optical Gravitational Lensing Experiment (OGLE-IV). We discuss several potential astrophysical applications of our collection: investigation of the structure of the Magellanic Clouds and the Galactic halo, studies of the globular clusters in the Magellanic System, analysis of double-mode RR Lyr stars, and search for RR Lyr stars in eclipsing binary systems.

  12. Field 1: A First Look at the KELT RR Lyrae Project

    NASA Astrophysics Data System (ADS)

    De Lee, Nathan M.; Kinemuchi, Karen; Pepper, Joshua; Rodriguez, Joseph E.; Paegert, Martin

    2015-01-01

    In this poster we will discuss our ongoing program to use extant light curves from the Kilodegree Extremely Little Telescope (KELT) survey to find and characterize RR Lyrae (RRL) stars in the disk and inner halo of the Milky Way. We will focus on initial results from our testbed region, Field 1. RRL stars are of particular interest because they are standard candles and can be used to map out structure in the galaxy. The periods and shape of RRL light curves also contain information about their Oosterhoff type, which can probe galactic formation history, and metallicity respectively. Although there have been several large photometric surveys for RR Lyrae in the nearby galaxy (OGLE, NSVS, ASAS, and MACHO to name a few), they have each been limited in either sky coverage or number of epochs. The KELT survey represents a new generation of surveys that has many epochs over a large portion of the sky. KELT samples 60% of the sky in both northern and southern hemispheres, and has a long-time-baseline of 4-8 years with a very high cadence rate of less than 20 minutes. This translates into 4,000 to 9,000 epochs per light curve with completeness out to 3 kpc from the Sun.Recent results from both Kepler and ground based surveys results suggest that as many as 50% of RR Lyrae stars show long-term modulation of their light curve shapes (Blazhko effect). These stars combined with RRL stars that pulsate in more than one mode give a sample of objects that the KELT survey is uniquely suited to explore. This poster uses the RR Lyrae stars in Field 1 of the KELT survey to compare detection methods to previous variable star surveys of the same region. We also discuss the individual RR Lyrae found in Field 1. In particular, we focus on initial characterization of RRL light curves including those with amplitude-modulated or period-modulated light curves. We uses these initial results to discuss future plans for this survey.

  13. Evidence for Distinct Components of the Galactic Stellar Halo from 838 RR Lyrae Stars Discovered in the LONEOS-I Survey

    SciTech Connect

    Miceli, A; Rest, A; Stubbs, C W; Hawley, S L; Cook, K H; Magnier, E A; Krisciunas, K; Bowell, E; Koehn, B

    2007-02-23

    We present 838 ab-type RR Lyrae stars from the Lowell Observatory Near Earth Objects Survey Phase I (LONEOS-I). These objects cover 1430 deg{sup 2} and span distances ranging from 3-30kpc from the Galactic Center. Object selection is based on phased, photometric data with 28-50 epochs. We use this large sample to explore the bulk properties of the stellar halo, including the spatial distribution. The period-amplitude distribution of this sample shows that the majority of these RR Lyrae stars resemble Oosterhoff type I, but there is a significant fraction (26%) which have longer periods and appear to be Oosterhoff type II. We find that the radial distributions of these two populations have significantly different profiles ({rho}{sub OoI} {approx} R{sup -2.26{+-}0.07} and {rho}{sub OoII} {approx} R{sup -2.88{+-}0.11}). This suggests that the stellar halo was formed by at least two distinct accretion processes and supports dual-halo models.

  14. Three-dimensional Maps of the Magellanic Clouds using RR Lyrae Stars and Cepheids. I. The Large Magellanic Cloud

    NASA Astrophysics Data System (ADS)

    Haschke, Raoul; Grebel, Eva K.; Duffau, Sonia

    2012-10-01

    The new data for Cepheids and RR Lyrae stars of the Optical Gravitational Lensing Experiment (OGLE III) survey allow us to study the three-dimensional distribution of stars corresponding to young (a few tens to a few hundreds of millions of years) and old (typically older than ~9 Gyr) populations of the Large Magellanic Cloud (LMC) traced by these variable stars. We estimate the distance to 16,949 RR Lyrae stars by using their photometrically estimated metallicities. Furthermore, the periods of 1849 Cepheids are used to determine their distances. Three-dimensional maps are obtained by using individual reddening estimates derived from the intrinsic color of these stars. The resulting median distances of the RR Lyrae stars and Cepheids appear to resolve the long and short distance scale problem for our sample. With median distances of 53.1 ± 3.2 kpc for the RR Lyrae stars and 53.9 ± 1.8 kpc for the Cepheids, these two distance indicators are in very good agreement with each other in contrast to a number of earlier studies. Individual reddening estimates allow us to resolve the distance discrepancies often observed while comparing Cepheids and RR Lyrae stars. For both stellar populations we find the inclination angle of the LMC to be 32° ± 4° and the mean position angle to be 115° ± 15°. The position angle increases with galactocentric radius, indicative of mild twisting. Within the innermost 7° of the LMC covered by OGLE III, the change in position angle amounts to more than 10°. The depth of the Cepheids is found to be 1.7 ± 0.2 kpc. The bar stands out as an overdensity both in RR Lyrae stars and in Cepheids. In RR Lyrae stars the bar can be traced as a protruding overdensity with a line-of-sight depth of almost 5 kpc in front of the main body of the disk.

  15. Finest light curve details, physical parameters, and period fluctuations of CoRoT RR Lyrae stars

    NASA Astrophysics Data System (ADS)

    Benkő, J. M.; Szabó, R.; Derekas, A.; Sódor, Á.

    2016-08-01

    The CoRoT satellite supplied the scientific community with a huge data base of variable stars. Among them the RR Lyrae stars have intensively been discussed in numerous papers in the last few years, but the latest runs have not been checked to find RR Lyrae stars up to now. Our main goal was to fill this gap and complete the CoRoT RR Lyrae sample. We found nine unstudied RR Lyrae stars. Seven of them are new discoveries. We identified three new Blazhko stars. The Blazhko effect shows non-strictly repetitive nature for all stars. The frequency spectrum of the Blazhko star CoRoT 104948132 contains second overtone frequency with the highest known period ratio. The harmonic amplitude and phase declines with the harmonic order were studied for non-Blazhko stars. We found a period dependent but similar shape amplitude decline for all stars. We discovered significant random period fluctuation for one of the two oversampled target, CM Ori. After a successful transformation of the CoRoT band parameters to the Johnson V values we estimated the basic physical properties such as mass, luminosity, metallicity. The sample can be divided into two subgroups with respect to the metallicity but otherwise the physical parameters are in the canonical range of RR Lyrae stars.

  16. AH Cam: A metal-rich RR Lyrae star with the shortest known Blazhko period

    NASA Technical Reports Server (NTRS)

    Smith, Horace A.; Matthews, Jaymie M.; Lee, Kevin M.; Williams, Jeffrey; Silbermann, N. A.; Bolte, Michael

    1994-01-01

    Analysis of 746 new V-band observations of the RR Lyrae star AH Cam obtained during 1989 - 1992 clearly show that its light curve cannot be described by a single period. In fact, at first glance, the Fourier spectrum of the photometry resembles that of a double-mode pulsator, with peaks at a fundamental period of 0.3686 d and an apparent secondary period of 0.2628 d. Nevertheless, the dual-mode solution is a poor fit to the data. Rather, we believe that AH Cam is a single-mode RR Lyrae star undergoing the Blazhko effect: periodic modulation of the amplitude and shape of its light curve. What was originally taken to be the period of the second mode is instead the 1-cycle/d alias of a modulation sidelobe in the Fourier spectrum. The data are well described by a modulation period of just under 11 d, which is the shortest Blazhko period reported to date in the literature and confirms the earlier suggestion by Goranskii. A low-resolution spectrum of AH Cam indicates that it is relatively metal rich, with delta-S less than or = 2. Its high metallicity and short modulation period may provide a critical test of at least one theory for the Blazhko effect. Moskalik's internal resonance model makes specific predictions of the growth rate of the fundamental model vs fundamental period. AH Cam falls outside the regime of other known Blazhko variables and resonance model predictions, but these are appropriate for metal-poor RR Lyrae stars. If the theory matches the behavior of AH Cam for a metal-rich stellar model, this would bolster the resonance hypothesis.

  17. Deep CCD Photometry and RR Lyrae Survey for the Outer-Halo Globular Cluster NGC 6229

    NASA Astrophysics Data System (ADS)

    Catelan, M.; Borissova, J.; Spassova, N.; Ferraro, F. R.; Buonanno, R.; Sweigart, A. V.

    1997-12-01

    Deep BV CCD photometry for a large field covering the outer-halo Galactic globular cluster NGC 6229 is presented. For the first time, a color-magnitude diagram (CMD) reaching below the main-sequence turnoff has been obtained for this cluster. Previous results regarding the overall morphology of the horizontal and giant branches are confirmed. In addition, several candidate blue straggler stars are identified. However, a preliminary analysis of the cluster's CMD suggests that the putative extreme horizontal branch population suggested by Borissova et al. (1997, AJ, 113, 692) may not be present. Unfortunately, the innermost cluster regions could not be studied due to crowding. Comparison of the cluster CMD locus with the latest isochrones from VandenBerg (1997, private communication) is also presented, as is a study of the cluster age relative to a few well-studied reference globulars, using both the ``horizontal" and ``vertical" methods. We also report on an investigation of the variable stars in NGC 6229. We obtained new light curves and re-derived the periods, amplitudes and mean V and B-V magnitudes for 17 RR Lyrae stars listed in Sawyer Hogg's (1973, Publ. David Dunlap Obs., 3, No. 6) catalog. We obtained the first light curves for the RR Lyrae candidates No. 155 and No. 88 (Carney et al. 1991, AJ, 101, 1699), and confirm variability of their star No. 134, as well as of the RR Lyrae stars V3, V8 and V12 suspected by Borissova et al. (1997). A search for variable stars in our 5 x 5 arcmin field does not lead to any new variable candidates.

  18. The luminosities of horizontal branches and RR Lyrae stars in globular clusters

    NASA Astrophysics Data System (ADS)

    McNamara, D. H.; Rose, M. B.; Brown, P. J.; Ketcheson, D. I.; Maxwell, J. E.; Smith, K. M.; Wooley, R. C.

    2004-05-01

    We have utilized the latest stellar models of the Y2 (Yonsei-Yale) collaborators and color-magnitude diagrams of globular clusters to infer ages and absolute magnitudes of their horizontal branches (HB). The intrinsic (B - V), color indices of the turn-offs, (B - V)TO0,of the globular clusters were used to find ages. For 47 clusters that appear to be coeval (within ± 0.7 Gyr), we find an average age of 12.5 Gyr. We adopt this age and infer the absolute magnitudes of the turn-offs, MTOV, from the clusters [Fe/H] values. The absolute magnitudes of the horizontal branches or RR Lyrae stars are the n determined from the difference between the apparent magnitudes of the horizontal branches (or RR Lyrae stars) and the apparent magnitude of the turn-offd, VTO. We conclude: 1) the slope of the MV(HB), [Fe/H] relation is ~0.3 for clusters with [Fe/H] values between -0.5 to -1.5. The relation has zero slope for [Fe/H] values smaller than -1.5. 2) For [Fe/H] < -1.3, the MV(HB) or MV values of RR Lyrae stars are not only a function of [Fe/H], but the horizontal-branch type in the sense that the clusters with the blue horizontal branches have more luminous horizontal branches than clusters with red horizontal branches. The same results are found by inferring the luminosities of the HBs from pulsating blue stragglers.

  19. A new overview of secular period changes of RR Lyrae stars in M5

    NASA Astrophysics Data System (ADS)

    Arellano Ferro, A.; Ahumada, J. A.; Kains, N.; Luna, A.

    2016-09-01

    Secular period variations, β =dot{P}, in 76 RR Lyrae stars in the globular cluster M5 are analysed using our most recent CCD V photometry and the historical photometric data base available in the literature since 1889. This provides a time baseline of up to 118 yr for these variables. The analysis was performed using two independent approaches: first, the classical O - C behaviour of the time of maximum light, and second, via a grid (P, β), where the solution producing the minimum scatter in the phased light curve is chosen. The results of the two methods agree satisfactorily. This allowed a new interpretation of the nature of the period changes in many RR Lyrae stars in M5. It is found that in 96 per cent of the stars studied no irregular or stochastic variations need to be claimed, but that 66 per cent of the population shows steady period increases or decreases, and that 34 per cent of the periods seem to have been stable over the last century. The lack of systematic positive or negative period variations in RR Lyrae stars in other globular clusters is addressed, and the paradigm of period changes being a consequence of stellar evolution is discussed in terms of chemical variations near the stellar core and of multiple stellar populations. In M5 we found a small positive average value of β and a small surplus of RRab stars with a period increase. Nevertheless, in M5 we have been able to isolate a group of likely evolved stars that systematically show positive, and in some cases large, period change rates.

  20. KELT RR Lyrae Variable Stars Observed by the NKU Schneider Observatory

    NASA Astrophysics Data System (ADS)

    De Lee, Nathan M.; Russell, Neil; Kinemuchi, Karen; Pepper, Joshua; Rodriguez, Joseph E.; Paegert, Martin

    2016-01-01

    In this poster we will discuss our ongoing program to use extant light curves from the Kilodegree Extremely Little Telescope (KELT) survey to find and characterize RR Lyrae (RRL) stars in the disk and inner halo of the Milky Way. RRL stars are of particular interest because they are standard candles and can be used to map out structure in the galaxy. The periods and shape of RRL light curves also contain information about their Oosterhoff type, which can probe galactic formation history, and metallicity respectively. Although there have been several large photometric surveys for RR Lyrae in the nearby galaxy (OGLE, NSVS, ASAS, and MACHO to name a few), they have each been limited in either sky coverage or number of epochs. The KELT survey represents a new generation of surveys that has many epochs over a large portion of the sky. KELT samples over 60% of the sky in both northern and southern hemispheres, and has a long-time-baseline of 4-10 years with a very high cadence rate of less than 20 minutes. This translates into 4,000 to 10,000+ epochs per light curve with completeness out to 3 kpc from the Sun. This poster will present follow-up data taken of RR Lyrae candidate stars found in the KELT survey. These stars were observed using an 11inch telescope at the NKU Schneider Observatory. We will discuss photometric accuracies, cadence, and initial analysis of these stars. We will also discuss the capabilities of our new observatory as well as future follow-up and analysis plans.

  1. A New Overview of Secular Period Changes of RR Lyrae stars in M5

    NASA Astrophysics Data System (ADS)

    Arellano Ferro, A.; Ahumada, J. A.; Kains, N.; Luna, A.

    2016-06-01

    Secular period variations, β =dot{P}, in 76 RR Lyrae stars in the globular cluster M5 are analysed using our most recent CCD V photometry and the historical photometric database available in the literature since 1889. This provides a time baseline of up to 118 years for these variables. The analysis was performed using two independent approaches: first, the classical O - C behaviour of the time of maximum light, and second, via a grid (P, β), where the solution producing the minimum scatter in the phased light curve is chosen. The results of the two methods agree satisfactorily. This allowed a new interpretation of the nature of the period changes in many RR Lyrae stars in M5. It is found that in 96% of the stars studied no irregular or stochastic variations need to be claimed, but that 66% of the population shows steady period increases or decreases, and that 34% of the periods seem to have been stable over the last century. The lack of systematic positive or negative period variations in RR Lyrae stars in other globular clusters is addressed, and the paradigm of period changes being a consequence of stellar evolution is discussed in terms of chemical variations near the stellar core and of multiple stellar populations. In M5 we found a small positive average value of β and a small surplus of RRab stars with a period increase. Nevertheless, in M5 we have been able to isolate a group of likely evolved stars that systematically show positive, and in some cases large, period change rates.

  2. Period-color and amplitude-color relations for RR Lyrae stars

    NASA Astrophysics Data System (ADS)

    Kanbur, S.; Bhardwaj, A.; Singh, H. P.; Ngeow, C. C.

    2016-05-01

    We use published OGLE LMC/SMC data to present comprehensive period-color (PC) and amplitude-color (AC) relations for both fundamental and overtone stars. For fundamental mode stars, we confirm earlier work that the minimum light extinction corrected PC relation in V - I has a shallow slope but with considerable scatter (LMC: [0.093+-0.019] with a standard deviation about this line of 0.116, SMC: [0.055+-0.058] with a standard deviation about this line of 0.099). We note the high scatter about this line for both the LMC and SMC: either there is some source of uncertainty in extinction or some other physical parameter is responsible for this dispersion. We compare with previous results and discuss some possible causes for this scatter. In contrast, RRc overtone stars do not obey a flat PC relation at minimum light (LMC: [0.604+-0.041] with a standard deviation about this line of 0.109, SMC: [0.472+-0.265] with a standard deviation about this line of 0.091). The fact that fundamental mode RR Lyrae stars obey a flat relation at minimum light and overtone RR Lyrae stars do not is consistent with the interaction of the stellar photosphere and hydrogen ionization front. We compare these results with PC relations for fundamental mode and first overtone Cepheids. The fact that the PC relations change significantly as a function of phase indicates strongly that Cepheid and RR Lyrae relations can only be understood at mean light when their properties as a function of phase are determined.

  3. Metal-rich or misclassified? The case of four RR Lyrae stars

    NASA Astrophysics Data System (ADS)

    Molnar, L.; Juhasz, A. L.; Plachy, E.; Szabo, R.

    2016-06-01

    We analysed the light curve of four, apparently extremely metal-rich fundamenta-mode RR Lyrae stars. We identified two stars, MT Tel and ASAS J091803-3022.6 as RRc (first-overtone) pulsators that were misclassified as RRab ones in the ASAS survey. In the case of the other two stars, V397 Gem and ASAS J075127-4136.3, we could not decide conclusively, as they are outliers in the period-Fourier-coefficient space from the loci of both classes, but their photometric metallicities also favour the RRc classification.

  4. Exploring the Milky Way halo with SDSS-II SN survey RR Lyrae stars

    NASA Astrophysics Data System (ADS)

    De Lee, Nathan

    This thesis details the creation of a large catalog of RR Lyrae stars, their lightcurves, and their associated photometric and kinematic parameters. This catalog contains 421 RR Lyrae stars with 305 RRab and 116 RRc. Of these, 241 stars have stellar spectra taken with either the Blanco 4m RC spectrograph or the SDSS/SEGUE survey, and in some cases taken by both. From these spectra and photometric methods derived from them, an analysis is conducted of the RR lyrae's distribution, metallicity, kinematics, and photometric properties within the halo. All of these RR Lyrae originate from the SDSS-II Supernova Survey. The SDSS-II SN Survey covers a 2.5 degree equatorial stripe ranging from -60 to +60 degrees in RA. This corresponds to relatively high southern galactic latitudes in the anti-center direction. The full catalog ranges from g 0 magnitude 13 to 20 which covers a distance of 3 to 95 kpc from the sun. Using this sample, we explore the Oosterhoff dichotomy through the D log P method as a function of | Z | distance from the plane. This results in a clear division of the RRab stars into OoI and OoII groups at lower | Z |, but the population becomes dominated by OoI stars at higher | Z |. The idea of a dual halo is explored primarily in the context of radial velocity distributions as a function of | Z |. In particular, V gsr , the radial velocity in the galactic standard of rest, is used as a proxy for V [straight phi] , the cylindrical rotational velocity. This is then compared against a single halo model galaxy, which results in very similar V gsr histograms for both at low to medium | Z |. However, at high | Z | there is a clear separation into two distinct velocity groups for the data without a corresponding separation in the model, suggesting that at least a two-component model for the halo is necessary. The final part of the analysis involves [Fe/H] measurements from both spectra and photometric relations cut in both | Z | and radial velocity. In this case

  5. Population synthesis of RR Lyrae stars in the original Kepler and K2 fields of view

    NASA Astrophysics Data System (ADS)

    Hanyecz, O.; Szabo, R.

    2016-05-01

    It is interesting to ask what fraction of the total available RR Lyrae (RRL) sample that falls in the Kepler and K2 Fields of View (FoV) is known or discovered. In order to answer this question we compared the known RRL sam- ple in the Kepler and K2 fields with synthetic Galactic models. The Catalina Sky Survey RRL sample was used to calibrate our method. We found that a large number of faint RRL stars is missing from Kepler and K2 fields.

  6. CHEMICAL ABUNDANCES OF METAL-POOR RR LYRAE STARS IN THE MAGELLANIC CLOUDS

    SciTech Connect

    Haschke, Raoul; Grebel, Eva K.; Duffau, Sonia; Frebel, Anna; Hansen, Camilla J.; Koch, Andreas

    2012-09-01

    We present for the first time a detailed spectroscopic study of chemical element abundances of metal-poor RR Lyrae stars in the Large and Small Magellanic Cloud (LMC and SMC). Using the MagE echelle spectrograph at the 6.5 m Magellan telescopes, we obtain medium resolution (R {approx} 2000-6000) spectra of six RR Lyrae stars in the LMC and three RR Lyrae stars in the SMC. These stars were chosen because their previously determined photometric metallicities were among the lowest metallicities found for stars belonging to the old populations in the Magellanic Clouds. We find the spectroscopic metallicities of these stars to be as low as [Fe/H]{sub spec} = -2.7 dex, the lowest metallicity yet measured for any star in the Magellanic Clouds. We confirm that for metal-poor stars, the photometric metallicities from the Fourier decomposition of the light curves are systematically too high compared to their spectroscopic counterparts. However, for even more metal-poor stars below [Fe/H]{sub phot} < -2.8 dex this trend is reversed and the spectroscopic metallicities are systematically higher than the photometric estimates. We are able to determine abundance ratios for 10 chemical elements (Fe, Na, Mg, Al, Ca, Sc, Ti, Cr, Sr, and Ba), which extend the abundance measurements of chemical elements for RR Lyrae stars in the Clouds beyond [Fe/H] for the first time. For the overall [{alpha}/Fe] ratio, we obtain an overabundance of 0.36 dex, which is in very good agreement with results from metal-poor stars in the Milky Way halo as well as from the metal-poor tail in dwarf spheroidal galaxies. Comparing the abundances with those of the stars in the Milky Way halo we find that the abundance ratios of stars of both populations are consistent with another. Therefore, we conclude that from a chemical point of view early contributions from Magellanic-type galaxies to the formation of the Galactic halo as claimed in cosmological models are plausible.

  7. Outward Bound with RR Lyrae Stars: Studies of the Outer Halo of the Milky Way

    NASA Astrophysics Data System (ADS)

    Cohen, Judith; Sesar, B.; Banholzer, S.

    2014-07-01

    We have isolated a sample of 734 RR Lyrae stars at distances beyond 50 kpc in the Milky Way halo from the Palomar Transient Facility database. We are using these to probe the density distribution in the halo out to about 100 kpc as well as the total mass of the Milky Way galaxy, which is still controversial and is important for near field cosmology. But we are hitting a number of limits in our effort to get further out. TMT coupled with a suitable wide field but deep multi-epoch imaging survey (i.e. LSST) will enable us to probe to the outer edge of our Galaxy.

  8. Near-infrared observations of RR Lyrae variables in omega Centauri .

    NASA Astrophysics Data System (ADS)

    Del Principe, M.; Piersimoni, A. M.; Storm, J.; Bono, G.; Caputo, F.; Cassisi, S.; Freyhammer, L. M.; Marconi, M.; Stetson, P. B.

    We present Near-Infrared (NIR) J and K_s-band observations for 181 RR Lyrae stars in the Galactic Globular Cluster omega Cen. The comparison between predicted and empirical slopes of NIR Period-Luminosity (PL) relations indicates a very good agreement. Cluster distance estimates based on NIR PL relations agree quite well with recent determinations based on different standard candles, giving a true mean distance modulus mu = 13.71±0.05, and d=5.52±0.13 kpc.

  9. Observing Globular Cluster RR Lyraes with the BYU West Mountain Observator

    NASA Astrophysics Data System (ADS)

    Jeffery, Elizabeth; Joner, Michael D.

    2016-01-01

    We have utilized the 0.9-meter telescope of the Brigham Young University West Mountain Observatory to secure data on six northern hemisphere globular clusters. Here we present observations of RR Lyrae stars located in these clusters, including light curves. We compare light curves produced using both DAOPHOT and ISIS software packages. Light curve fitting is done with FITLC. We acknowledge continued support from the Brigham Young University College of Physical and Mathematical sciences for operation of the West Mountain Observatory. Some of the observations included in this presentation were secured within the term of NSF grant AST-0618209.

  10. Observing Globular Cluster RR Lyrae Variables with the BYU West Mountain Observatory

    NASA Astrophysics Data System (ADS)

    Jeffery, E. J.; Joner, M. D.

    2016-06-01

    We have utilized the 0.9-meter telescope of the Brigham Young University West Mountain Observatory to secure data on six northern hemisphere globular clusters. Here we present representative observations of RR Lyrae stars located in these clusters, including light curves. We compare light curves produced using both DAOPHOT and ISIS software packages. Light curve fitting is done with FITLC. We find that for well-separated stars, DAOPHOT and ISIS provide comparable results. However, for stars within the cluster core, ISIS provides superior results. These improved techniques will allow us to better measure the properties of cluster variable stars.

  11. A Swift/UVOT Survey of RR Lyrae Stars in the M2 and Omega Centauri Globular Clusters

    NASA Astrophysics Data System (ADS)

    Siegel, Michael; Balzer, Benjamin

    2016-01-01

    We present new results from our ongoing Near Ultraviolet (UV) survey of RR Lyrae variable stars in globular clusters using the Swift Ultraviolet Optical Telescope (UVOT). Our previous investigations have shown that RR Lyrae have strong pulsations in the UV. The pulsational parameters show correlations similar to those seen in the optical/IR, including a strong period-shift, period-amplitude relationship and period-temperature relationship. We have also seen a period-luminosity relationship that has a strong dependence on metallicity. We now examine the NUV properties of RR Lyrae in two additional clusters, M2 and Omega Centauri. We show that these two clusters follow the same paradigm and shed new light on the period-luminosity relationship.

  12. ON THE MODULATION OF RR LYRAE STARS IN THE GLOBULAR CLUSTER M3

    SciTech Connect

    Jurcsik, J.; Smitola, P.; Nuspl, J.; Hajdu, G.

    2014-12-10

    New, extended time-series photometry of M3 RR Lyrae stars has revealed that 4 of the 10 double-mode stars show large-amplitude Blazhko modulation of both radial modes. The first, detailed analysis of the peculiar behavior of the unique, Blazhko RRd stars is given. While the P1/P0 period ratio is normal, and the overtone mode is dominant in the other RRd stars of the cluster, the period ratio is anomalous and the fundamental mode has a larger (or similar) mean amplitude than the overtone has in Blazhko RRd stars. The modulations of the fundamental and overtone modes are synchronized only in one of the Blazhko RRd stars. No evidence of any connection between the modulations of the modes in the other three stars is found. The Blazhko modulation accounts, at least partly, for the previously reported amplitude and period changes of these stars. Contrary to the ∼50% Blazhko statistics of RRab and RRd stars, Blazhko modulation occurs only in 10% of the overtone variables in M3. Four of the five Blazhko RRc stars are bright, evolved objects, and one has a period and brightness similar to those of Blazhko RRd stars. The regions of the instability strip with high and low occurrence rates of the Blazhko modulation overlap with the regions populated by first- and second-generation stars according to theoretical and observational studies, raising up the possibility that the Blazhko modulation occurs preferentially in first-generation RR Lyrae stars.

  13. The Blazhko Effect and Additional Excited Modes in RR Lyrae Stars

    NASA Astrophysics Data System (ADS)

    Benkő, J. M.; Szabó, R.

    2015-08-01

    Recent photometric space missions, such as CoRoT and Kepler, revealed that many RR Lyrae stars pulsate—beyond their main radial pulsation mode—in low-amplitude modes. Space data seem to indicate a clear trend that, namely, overtone (RRc) stars and modulated fundamental (RRab) RR Lyrae stars ubiquitously show additional modes, while non-Blazhko RRab stars never do. Two Kepler stars (V350 Lyr and KIC 7021124), however, apparently seemed to break this rule: they were classified as non-Blazhko RRab stars showing additional modes. We processed Kepler pixel photometric data of these stars. We detected a small amplitude (but significant) Blazhko effect for both stars by using the resulting light curves and O-C diagrams. This finding strengthens the apparent connection between the Blazhko effect and the excitation of additional modes. In addition, it yields a potential tool for detecting Blazhko stars through the additional frequency patterns, even if we have only short but accurate time series observations. V350 Lyr shows the smallest amplitude multiperiodic Blazhko effect ever detected.

  14. Expanded RR Lyrae Search in the Southern Hemisphere with the La Silla-QUEST Survey

    NASA Astrophysics Data System (ADS)

    Horowitz, Benjamin; Zinn, R.; Charles, B.; Coppi, P. S.; Ellman, N. E.; Fowler, G.; Hadjiyska, E. I.; Rabinowitz, D. L.; Vivas, K.

    2014-01-01

    We present the recent work of the La Silla-QUEST (LSQ) Variability Survey on RR Lyrae stars (RRLS) and their use as probes of galactic halo structure. While past RR Lyrae surveys with LSQ were limited to areas overlapping the Sloan Digital Sky Survey, in order to expand our survey beyond overlap with SDSS we select RRLS candidates on the basis of their B-R colors in the Palomar drift-scan survey. This enables the LSQ survey to cover the declination band from -24 to +25 deg. and all right ascensions except where the band is less than 18 deg from the galactic plane. The LSQ survey for both type ab and c RRLS is approximately 70% complete over the magnitude range 14 to 20 in V, which in directions of low interstellar extinction corresponds to distances from roughly 5 to 75 kpc. Results on galactic structure and Oosterhoff properties of Type ab and c variables will be presented for a subregion of the survey. This research has been supported by NSF grant AST-1108948 and DOE grant DE FG0 ER92 40704 to Yale University and by the Provost Office of Yale University.

  15. THE DYNAMICAL DISTANCE, RR LYRAE ABSOLUTE MAGNITUDE, AND AGE OF THE GLOBULAR CLUSTER NGC 6266

    SciTech Connect

    McNamara, Bernard J.; McKeever, Jean E-mail: jeanm12@nmsu.edu

    2011-11-15

    The internal proper motion dispersion of NGC 6266 was measured using Hubble Space Telescope Wide Field Planetary Camera 2 images with an epoch difference of eight years. The dispersion was found to be 0.041 {+-} 0.001 arcsec century{sup -1}. This value was then equated to the cluster's radial velocity dispersion of 13.7 {+-} 1.1 km s{sup -1} to yield a distance to NGC 6266 of 7054 {+-} 583 pc. Based on this distance we find that the NGC 6266 RR Lyrae stars have M{sub V} = 0.51 {+-} 0.18 mag. This magnitude is in good agreement with that predicted by the M{sub V} versus [Fe/H] relation found by Benedict et al. Using an average [Fe/H] of -1.25 for NGC 6266, their relation predicts M{sub V} = 0.49 {+-} 0.06. Based on the RR Lyrae M{sub V} versus age relation determined by Chaboyer et al., we estimate that NGC 6266 has an age of 11.4 {+-} 2.2 Gyr.

  16. VizieR Online Data Catalog: Field RR Lyrae stars (Liska+, 2016)

    NASA Astrophysics Data System (ADS)

    Liska, J.; Skarka, M.; Zejda, M.; Mikulasek, Z.; de Villiers, S. N.

    2016-05-01

    Differential photometry for VX Her in 'table1.dat' file. New photometric measurements for VX Her were performed at Masaryk University Observatory, Brno, Czech Republic during 13 nights (April-August 2014) with 0.6-m (24-inch) Newtonian telescope, CCD G2-0402, in BVRI bands. CCD images were calibrated in a standard way (dark frame and flat field corrections). The C-Munipack software (Motl 2009) was used for this processing as well as for differential photometry. TYC 1510-269-1 and TYC 1510-149-1 were used as comparison and check stars, respectively. Differential photometry for AT Ser and SS Leo is in 'table2.dat' file. New photometric measurements for these two stars were obtained using 1-inch refractor (a photographic lens Sonnar 4/135mm, lens focal ratio/focal length) and ATIK 16IC CCD camera with green photometric filter with similar throughput as the Johnson V filter. Exposures were 30s and each five frames were combined to a single image to achieve a better signal-to-noise ratio. The time resolution of a such combined frame is about 170s. The comparison stars were HD 142799 for AT Ser and HD 100763 for SS Leo. List with candidates for binaries with RR Lyrae component - RRLyrBinCan database (version 2016 May 5) is in 'table3.dat' file. 'table4.dat' file contains false-positives binary candidates among RR Lyrae stars. 'table5.dat' and 'table6.dat' files contain used maxima timings given in GEOS RR Lyr database, or newly determined in this study. (7 data files).

  17. The CRRP and SMHASH programs: Mapping the Milky Way and its neighbours with RR Lyraes in the mid IR

    NASA Astrophysics Data System (ADS)

    Scowcroft, Victoria; Freedman, Wendy L.; Johnston, Kathryn V.; Madore, Barry; Crrp Team, Smhash Team

    2015-01-01

    The CRRP and SMHASH programs are Spitzer Warm mission programs studying RR Lyrae in the Milky Way and its nearest neighbors.The calibration program (CRRP) studies individual calibrator RR Lyrae stars that will be observed by Gaia, in addition to 45 MW and LMC globular clusters and 36 fields in the MW bulge and halo. These observations provide the calibration of the RR Lyrae mid-IR PL relation, allow us to measure metallicity effects using objects such as ω Cen, and will allow us to study the structure of the MW itself.Our follow-on program, SMHASH, builds on the CRRP foundation to do a larger scale structural study of the MW. In this program we have targeted the Sagittarius dwarf, Sagittarius and Orphan Streams and several dwarf galaxies neighboring the MW.I will discuss the two programs, giving preliminary results showing the first measurements of the RR Lyrae mid-IR PL relation from full phase coverage observations. I will show how the measurements from CRRP/SMHASH are critical for both the structural studies of the MW and for an independent measure of the distance to the LMC, providing a complementary test of the Cepheid distance ladder.

  18. Ground-Based BVRI Time-Series Follow-Up Observations for the RR Lyrae stars in Kepler Field

    NASA Astrophysics Data System (ADS)

    Jeon, Young-Beom; Ngeow, Chow-Choong; Nemec, James M.

    2015-09-01

    Time series observations for the 41 RR Lyrae stars in Kepler's fields were carried out in 2010 to 2013 using a number of meter class (or smaller) telescopes. These telescopes include the 1-m and 41-cm telescopes of Lulin Observatory (LOT and SLT respectively, Taiwan), the 81-cm telescope of Tenagra-II Observatory (TNG, Arizona, USA), the 1-m telescope at the Mt. Lemmon Optical Astronomy Observatory (LOAO, Arizona, USA), the 1.8-m and 15-cm telescopes at the Bohyunsan Optical Astronomy Observatory (BOAO, Korea), and the 61-cm telescope at the Sobaeksan Optical Astronomy Observatory (SOAO, Korea). All of these telescopes were equipped with commercial available CCD imagers, and the observations were done in standard BVRI filters. Photometric calibration of the RR Lyrae light curves was done with standard stars listed in Landolt standard stars [1]. Observations of selected Landolt standard stars (centered on SA 107-456 & SA 110-232) in Johnson-Kron-Cousins BVRI filters, spanning three distinct airmasses, were done with the 81-cm Tenagra II telescope on 25 June 2011. Raw imaging data were reduced with IRAF in the same manner as in the case of the RR Lyrae, and astrometric calibrated with astrometry.net [2]. We calibrated BVRI magnitudes for 40 RR Lyrae stars.

  19. THREE-DIMENSIONAL MAPS OF THE MAGELLANIC CLOUDS USING RR LYRAE STARS AND CEPHEIDS. I. THE LARGE MAGELLANIC CLOUD

    SciTech Connect

    Haschke, Raoul; Grebel, Eva K.; Duffau, Sonia

    2012-10-01

    The new data for Cepheids and RR Lyrae stars of the Optical Gravitational Lensing Experiment (OGLE III) survey allow us to study the three-dimensional distribution of stars corresponding to young (a few tens to a few hundreds of millions of years) and old (typically older than {approx}9 Gyr) populations of the Large Magellanic Cloud (LMC) traced by these variable stars. We estimate the distance to 16,949 RR Lyrae stars by using their photometrically estimated metallicities. Furthermore, the periods of 1849 Cepheids are used to determine their distances. Three-dimensional maps are obtained by using individual reddening estimates derived from the intrinsic color of these stars. The resulting median distances of the RR Lyrae stars and Cepheids appear to resolve the long and short distance scale problem for our sample. With median distances of 53.1 {+-} 3.2 kpc for the RR Lyrae stars and 53.9 {+-} 1.8 kpc for the Cepheids, these two distance indicators are in very good agreement with each other in contrast to a number of earlier studies. Individual reddening estimates allow us to resolve the distance discrepancies often observed while comparing Cepheids and RR Lyrae stars. For both stellar populations we find the inclination angle of the LMC to be 32 Degree-Sign {+-} 4 Degree-Sign and the mean position angle to be 115 Degree-Sign {+-} 15 Degree-Sign . The position angle increases with galactocentric radius, indicative of mild twisting. Within the innermost 7 Degree-Sign of the LMC covered by OGLE III, the change in position angle amounts to more than 10 Degree-Sign . The depth of the Cepheids is found to be 1.7 {+-} 0.2 kpc. The bar stands out as an overdensity both in RR Lyrae stars and in Cepheids. In RR Lyrae stars the bar can be traced as a protruding overdensity with a line-of-sight depth of almost 5 kpc in front of the main body of the disk.

  20. THREE-DIMENSIONAL MAPS OF THE MAGELLANIC CLOUDS USING RR LYRAE STARS AND CEPHEIDS. II. THE SMALL MAGELLANIC CLOUD

    SciTech Connect

    Haschke, Raoul; Grebel, Eva K.; Duffau, Sonia

    2012-10-01

    We use data on variable stars from the Optical Gravitational Lensing Experiment survey to determine the three-dimensional structure of the Small Magellanic Cloud (SMC). Deriving individual distances to RR Lyrae stars and Cepheids, we investigate the distribution of these tracers of the old and young populations in the SMC. Photometrically estimated metallicities are used to determine the distances to 1494 RR Lyrae stars, which have typical ages greater than 9 Gyr. For 2522 Cepheids, with ages of a few tens to a few hundred Myr, distances are calculated using their period-luminosity relation. Individual reddening estimates from the intrinsic color of each star are used to obtain high precision three-dimensional maps. The distances of RR Lyrae stars and Cepheids are in very good agreement with each other. The median distance of the RR Lyrae stars is found to be 61.5 {+-} 3.4 kpc. For the Cepheids, a median distance of 63.1 {+-} 3.0 kpc is obtained. Both populations show an extended scale height, with 2.0 {+-} 0.4 kpc for the RR Lyrae stars and 2.7 {+-} 0.3 kpc for the Cepheids. This confirms the large depth of the SMC suggested by a number of earlier studies. The young population is very differently oriented than the old stars. While we find an inclination angle of 7 Degree-Sign {+-} 15 Degree-Sign and a position angle of 83 Degree-Sign {+-} 21 Degree-Sign for the RR Lyrae stars, for the Cepheids an inclination of 74 Degree-Sign {+-} 9 Degree-Sign and a position angle of 66 Degree-Sign {+-} 15 Degree-Sign is obtained. The RR Lyrae stars show a fairly homogeneous distribution, while the Cepheids roughly follow the distribution of the bar, with their northeastern part being closer to us than the southwestern part of the bar. Interactions between the SMC, Large Magellanic Cloud, and Milky Way are presumably responsible for the tilted, elongated structure of the young population of the SMC.

  1. Galactic archaeology for amateur astronomers: RR Lyrae stars as tracers of the Milky Way formation

    NASA Astrophysics Data System (ADS)

    Carballo-Bello, Julio A.; Martínez-Delgado, David; Fliri, Jürgen

    2011-06-01

    Cosmological models predict that large galaxies like the Milky Way formed from the accretion of smaller stellar systems. The most spectacular of these merger events are stellar tidal streams, rivers of stars and dark matter that envelop the discs of spiral galaxies. We present a research project for a collaboration with amateur astronomers in the study of the formation process of our Galaxy. The main objective is the search for RR Lyrae variable stars in the known stellar streams (Sagitarius, Monoceros, Orphan, etc) a project that can be carried out using small telescopes. The catalogue of candidate variable stars were selected from SDSS data based in colour criteria and it will be sent to interested amateur astronomers who wish to participate in scientific research in one of the most active and competitive topics in Galactic astronomy.

  2. Study of the period changes in SW Dor, an RR Lyrae type star with Blazhko effect

    NASA Astrophysics Data System (ADS)

    Berdnikov, L. N.; Kniazev, A. Y.; Dambis, A. K.; Kravtsov, V. V.; Sefako, R.

    2016-09-01

    In 2012-2014 we acquired 1569 CCD BVIc frames for the RR Lyrae type variable SW Dor with the 76-cm telescope of the South African Astronomical Observatory (SAAO) and 1-m telescopes of Las Cumbres Observatory Global Telescope network (LCOGT). Our observations showed a large scatter in the resulting phased light curve, especially near maximum brightness, which allowed us to reveal the Blazhko effect with a period of ˜80.9d. To study the pulsation period changes, we used all the available observations including the 1299 magnitude estimates from the digitized plate library of Harvard University (the DASCH project), which allowed us to construct the O-C diagram spanning a 125-year long time interval and discover for the first time at least three abrupt changes of the pulsation period.

  3. VizieR Online Data Catalog: Equivalent width of 21 RR Lyrae stars (Pancino+, 2015)

    NASA Astrophysics Data System (ADS)

    Pancino, E.; Britavskiy, N.; Romano, D.; Cacciari, C.; Mucciarelli, A.; Clementini, G.

    2015-02-01

    Equivalent widths and atomic data of the absorption lines used in the abundance analysis, for each separate exposure at different phases. Observations of 15 RR Lyrae stars (DR And, X Ari, TW Boo, RZ Cam, RX Cet, U Com, RV CrB, SW CVn, UZ CVn, AE Dra, SZ Gem, VX Her, DH Hya, TU UMa, and RV UMa) and one BL Her star (UY Eri) were carried out with SARG@TNG, operated on the island of La Palma, Spain, during two separate runs in 2009 March and between September and November. Eight stars (SW Aqr, TW Cap, DH Hya, V Ind, SS Leo, V716 Oph, BK Tuc, and UV Vir) were observed with UVES@VLT, between 2009 April and August in service mode. (3 data files).

  4. Nonradial modes in RR Lyrae stars from the OGLE Collection of Variable Stars

    NASA Astrophysics Data System (ADS)

    Netzel, H.; Smolec, R.; Moskalik, P.

    2016-05-01

    The Optical Gravitational Lensing Experiment (OGLE) is a great source of top-quality photometry of classical pulsators. A collection of variable stars from the fourth part of the project contains more than 38 000 RR Lyrae stars. These stars pulsate mostly in the radial fundamental mode (RRab), in radial first overtone (RRc) or in both modes simultaneously (RRd). Analysis of the OGLE data allowed to detect additional nonradial modes in RRc and in RRd stars. We have found more than 260 double-mode stars with characteristic period ratio of the additional (shorter) period to first overtone period around 0.61, increasing the number of known stars of this type by a factor of 10. Stars from the OGLE sample form three nearly parallel sequences in the Petersen diagram. Some stars show more than one nonradial mode simultaneously. These modes belong to different sequences.

  5. The RR Lyrae period-K-luminosity relation for globular clusters: an observational approach

    NASA Astrophysics Data System (ADS)

    Sollima, A.; Cacciari, C.; Valenti, E.

    2006-11-01

    The period-metallicity-K-band luminosity (PLK) relation for RR Lyrae stars in 15 Galactic globular clusters and in the Large Magellanic Cloud (LMC) globular cluster Reticulum has been derived. It is based on accurate near-infrared (K) photometry combined with Two-Micron All-Sky Survey (2MASS) and other literature data. The PLK relation has been calibrated and compared with the previous empirical and theoretical determinations in literature. The zero point of the absolute calibration has been obtained from the K magnitude of RR Lyr whose distance modulus has been measured via trigonometric parallax with Hubble Space Telescope (HST). Using this relation, we obtain a distance modulus to the LMC of (m - M)0 = 18.54 +/- 0.15 mag, in good agreement with recent determinations based on the analysis of Cepheid variable stars. Based on observations collected at the European Southern Observatory within the observing programs 49.5-0021, 51.5-0024, 59.E-0340, 64.N-0038, 68.D-0287 and at the Telescopio Nazionale Galileo. E-mail: antonio.sollima@bo.astro.it (AS)

  6. VizieR Online Data Catalog: Abundances of 8 RR Lyrae subclass C variable stars (Govea+, 2014)

    NASA Astrophysics Data System (ADS)

    Govea, J.; Gomez, T.; Preston, G. W.; Sneden, C.

    2016-02-01

    We chose 10 candidate RR Lyrae variable stars of subclass c (RRc) stars for spectroscopic observation. Many of these stars were first identified as RRc variables by the All Sky Automated Survey (ASAS) of Pojmanski 2003 (cat. II/264). The target star list included ASAS 144154-0324.7 and ASAS 204440-2402.7. But our spectroscopic study suggest that these two stars are probably W UMa binaries instead of RR Lyrae stars Our spectra were obtained with the echelle spectrograph of the du Pont 2.5m telescope at the Las Campanas Observatory. Four observing runs during 2009-2010 were partly devoted to this project. The spectrograph was used with the 1.5*4'' entrance slit, which translates to a resolving power of R=λ/Δλ~27000 at the MgI b lines near 5180Å. The total continuous wavelength coverage of the spectra was 3500-9000Å. (6 data files).

  7. A PRELIMINARY CALIBRATION OF THE RR LYRAE PERIOD-LUMINOSITY RELATION AT MID-INFRARED WAVELENGTHS: WISE DATA

    SciTech Connect

    Madore, Barry F.; Freedman, Wendy L.; Kollmeier, Juna A.; Monson, Andy; Eric Persson, S.; Rich, Jeff A. Jr.; Scowcroft, Victoria; Seibert, Mark; Hoffman, Douglas E-mail: wendy@obs.carnegiescience.edu E-mail: amonson@obs.carnegiescience.edu E-mail: jrich@obs.carnegiescience.edu E-mail: mseibert@obs.carnegiescience.edu

    2013-10-20

    Using time-resolved, mid-infrared data from the Wide-field Infrared Survey Explorer (WISE) and geometric parallaxes from the Hubble Space Telescope for four Galactic RR Lyrae variables, we derive the following Population II period-luminosity (PL) relations for the WISE [W1], [W2], and [W3] bands at 3.4, 4.6, and 12 μm, respectively: The slopes and the scatter around the fits are consistent with a smooth extrapolation of those same quantities from previously published K-band observations at 2.2 μm, where the asymptotic (long-wavelength) behavior is consistent with a period-radius relation with a slope of 0.5. No obvious correlation with metallicity (spanning 0.4 dex in [Fe/H]) is found in the residuals of the four calibrating RR Lyrae stars about the mean PL regression line.

  8. LIGHT CURVE TEMPLATES AND GALACTIC DISTRIBUTION OF RR LYRAE STARS FROM SLOAN DIGITAL SKY SURVEY STRIPE 82

    SciTech Connect

    Sesar, Branimir; Ivezic, Zeljko; Grammer, Skyler H.; Morgan, Dylan P.; Becker, Andrew C.; Juric, Mario; De Lee, Nathan; Annis, James; Lampeitl, Hubert; Beers, Timothy C.; Fan Xiaohui; Jiang Linhua; Lupton, Robert H.; Gunn, James E.; Knapp, Gillian R.; Johnston, David E.; Jester, Sebastian

    2010-01-01

    We present an improved analysis of halo substructure traced by RR Lyrae stars in the Sloan Digital Sky Survey (SDSS) stripe 82 region. With the addition of SDSS-II data, a revised selection method based on new ugriz light curve templates results in a sample of 483 RR Lyrae stars that is essentially free of contamination. The main result from our first study persists: the spatial distribution of halo stars at galactocentric distances 5-100 kpc is highly inhomogeneous. At least 20% of halo stars within 30 kpc from the Galactic center can be statistically associated with substructure. We present strong direct evidence, based on both RR Lyrae stars and main-sequence stars, that the halo stellar number density profile significantly steepens beyond a Galactocentric distance of approx30 kpc, and a larger fraction of the stars are associated with substructure. By using a novel method that simultaneously combines data for RR Lyrae and main-sequence stars, and using photometric metallicity estimates for main-sequence stars derived from deep co-added u-band data, we measure the metallicity of the Sagittarius dSph tidal stream (trailing arm) toward R.A. approx2{sup h}-3{sup h} and decl. approx 0{sup 0} to be 0.3 dex higher ([Fe/H] = -1.2) than that of surrounding halo field stars. Together with a similar result for another major halo substructure, the Monoceros stream, these results support theoretical predictions that an early forming, smooth inner halo, is metal-poor compared to high surface brightness material that have been accreted onto a later-forming outer halo. The mean metallicity of stars in the outer halo that are not associated with detectable clumps may still be more metal-poor than the bulk of inner-halo stars, as has been argued from other data sets.

  9. ON THE PERIOD DISTRIBUTION OF CLUSTER RR LYRAE STARS TO CONSTRAIN THEIR HELIUM CONTENT: THE CASE OF {omega} CENTAURI

    SciTech Connect

    Marconi, M.; Bono, G.; Caputo, F.; Piersimoni, A. M.; Pietrinferni, A.; Stellingwerf, R. F. E-mail: giuseppe.bono@roma2.infn.it E-mail: piersimoni@oa-teramo.inaf.it E-mail: rfs@swcp.com

    2011-09-01

    We present new sets of nonlinear, time-dependent convective hydrodynamical models of RR Lyrae stars assuming two metal (Z = 0.0005, Z = 0.001) and three helium abundances (Y = 0.24, 0.30, 0.38). For each chemical composition, we constructed a grid of fundamental and first overtone models covering a broad range of stellar masses and luminosities. To constrain the impact of the helium content on RR Lyrae properties, we adopted two observables-period distribution and luminosity amplitudes-that are independent of distance and reddening. The current predictions confirm that the helium content has a marginal effect on the pulsation properties. The key parameter causing the difference between canonical and He-enhanced observables is the luminosity. We compared current predictions with the sample of 189 RR Lyrae stars in {omega} Cen and found that the period range of He-enhanced models is systematically longer than observed. These findings apply to metal-poor and metal-intermediate He-enhanced models. To further constrain the impact of He-enhanced structures on the period distribution, we also computed a series of synthetic horizontal branch (HB) models and found that the predicted period distribution, based on a Gaussian sampling in mass, agrees quite well with observations. This applies not only to the minimum fundamentalized period of RR Lyrae stars (0.39 versus 0.34 days) but also to the fraction of Type II Cepheids (2% versus 3%). We also computed a series of synthetic HB models assuming a mixed HB population in which the 80% is made of canonical HB structures, while the 20% is made of He-enhanced (Y = 0.30) HB structures. We found that the fraction of Type II Cepheids predicted by these models is almost a factor of two larger than observed (5% versus 3%). This indicates that the fraction of He-enhanced structures in {omega} Cen cannot be larger than 20%.

  10. The visual surface brightness relation and the absolute magnitudes of RR Lyrae stars. I - Theory

    NASA Technical Reports Server (NTRS)

    Manduca, A.; Bell, R. A.

    1981-01-01

    A theoretical relation analogous to the Barnes-Evans relation between stellar surface brightness and V-R color is derived which is applicable to the temperatures and gravities appropriate to RR Lyrae stars. Values of the visual surface brightness and V-R colors are calculated for model stellar atmospheres with effective temperatures between 6000 and 8000 K, log surface gravities from 2.2 to 3.5, and A/H anbundance ratios from -0.5 to -3.0. The resulting relation is found to be in reasonable agreement with the empirical relation of Barnes, Evans and Moffet (1978), with, however, small sensitivities to gravity and metal abundance. The relation may be used to derive stellar angular diameters from (V,R) photometry and to derive radii, distances, and absolute magnitudes for variable stars when combined with a radial velocity curve. The accuracies of the radii and distances (within 10%) and absolute magnitudes (within 0.25 magnitudes) compare favorably with those of the Baade-Wesselink method currently in use.

  11. RR LYRAE VARIABLES IN THE LOCAL GROUP DWARF GALAXY NGC 147

    SciTech Connect

    Yang, S-C.; Sarajedini, Ata E-mail: ata@astro.ufl.ed

    2010-01-01

    We investigate the RR Lyrae (RRL) population in NGC 147, a dwarf satellite galaxy of M31 (Andromeda). We used both Thuan-Gunn g-band ground-based photometry from the literature and Hubble Space Telescope Wide Field Planetary Camera 2 archival data in the F555W and F814W passbands to investigate the pulsation properties of RRL variable candidates in NGC 147. These data sets represent the two extreme cases often found in RRL studies with respect to the phase coverage of the observations and the quality of the photometric measurements. Extensive artificial variable star tests for both cases were performed. We conclude that neither data set is sufficient to confidently determine the pulsation properties of the NGC 147 RRLs. Thus, while we can assert that NGC 147 contains RRL variables, and therefore a population older than approx10 Gyr, it is not possible at this time to use the pulsation properties of these RRLs to study other aspects of this old population. Our results provide a good reference for gauging the completeness of RRL variable detection in future studies.

  12. NO EXCESS OF RR LYRAE STARS IN THE CANIS MAJOR OVERDENSITY

    SciTech Connect

    Mateu, Cecilia; Vivas, A. Katherina; Abad, Carlos; Zinn, Robert; Miller, Lissa R. E-mail: vivas@cida.ve E-mail: robert.zinn@yale.edu

    2009-05-15

    Our multi-epoch survey of {approx}20 deg{sup 2} of the Canis Major (CMa) overdensity has detected only 10 RR Lyrae stars (RRLS). We show that this number is consistent with the number expected from the Galactic halo and thick disk populations alone, leaving no excess that can be attributed to the dwarf spheroidal (dSph) galaxy that some authors have proposed as the origin of the CMa overdensity. If this galaxy resembles the dSph satellites of the Milky Way (MW) and of M31 and has the putative M{sub V} {approx} -14.5, our survey should have detected several tens of RRLS. Even if M{sub V} {approx}< -12, the expected excess is {approx}>10, which is not observed. Either the old stellar population of this galaxy has unique properties or, as others have argued before, the CMa overdensity is produced by the thin and thick disk and spiral arm populations of the MW and not by a collision with a dSph satellite galaxy.

  13. TU Comae Berenices: Blazhko RR Lyrae Star in a Potential Binary System

    NASA Astrophysics Data System (ADS)

    de Ponthière, P.; Hambsch, F.-J.; Menzies, K.; Sabo, R.

    2016-06-01

    We present the results of a photometry campaign of TU Com performed over a five-year time span. The analysis showed that the possible Blazhko period of 75 days published by the General Catalogue of Variable Stars is not correct. We identified two Blazhko periods of 43.6 and 45.5 days. This finding is based on measurement of 124 light maxima. A spectral analysis of the complete light curve confirmed these two periods. Besides the Blazhko amplitude and phase modulations, another long term periodic phase variation has been identified. This long term periodic variation affects the times of maximum light only and can be attributed to a light-travel time effect due to orbital motion of a binary system. The orbital parameters have been estimated by a nonlinear least-square fit applied to the set of (O-C) values. The Levenberg-Marquart algorithm has been used to perform the nonlinear least-square fit. The tentative orbital parameters include an orbital period of 1676 days, a minimal semi-major axis of 1.55 AU and a small eccentricity of 0.22. The orbital parameter estimation also used 33 (O-C) values obtained from the SWASP survey database. Spectroscopic radial velocity measurements are needed to confirm this binarity. If confirmed, TU Com would be the first Blazhko RR Lyrae star detected in a binary system.

  14. Harmonizing the RR Lyrae and Clump Distance Scales-Stretching the Short Distance Scale to Intermediate Ranges?

    SciTech Connect

    Popowski, P.

    2000-01-31

    I explore the consequences of making the RR Lyrae and clump giant distance scales consistent in the solar neighborhood, Galactic bulge and Large Magellanic Cloud (LMC). I employ two major assumptions: (1) that the absolute magnitude -metallicity, M{sub V}(RR) - [Fe/H], relation for RR Lyrae stars is universal, and (2) that absolute I-magnitudes of clump giants, M{sub I}(RC), in Baade's Window can be inferred from the local Hipparcos calibration of clump giants' magnitudes. A comparison between the solar neighborhood and Baade's Window sets M{sub V}(RR) at [Fe/H] = -1.6 in the range (0.59 {+-} 0.05, 0.70 {+-} 0.05), somewhat brighter than the statistical parallax solution. A comparison between Baade's Window and the LMC sets the M{sub I}{sup LMC}(RC) in the range (-0.33 {+-} 0.09, -0.53 {+-} 0.09). The distance modulus to the LMC is {mu}{sup LMC} {element_of} (18.24 {+-} 0.08, 18.44 {+-} 0.07). I argue that the currently available information slightly favors the short distance scale but is insufficient to select the correct solutions with high confidence.

  15. Lyra

    NASA Astrophysics Data System (ADS)

    Murdin, P.

    2000-11-01

    (the Lyre; abbrev. Lyr, gen. Lyrae; area 286 sq. deg.) A northern constellation which lies between Hercules and Cygnus, and culminates at midnight in early July. It is an ancient constellation pattern, which was associated with an eagle or vulture in the Indian subcontinent and Arab countries, and with the mythical lyre invented by Hermes and given by Apollo to Orpheus in ancient Greece. Its brig...

  16. First stars. XIII. Two extremely metal-poor RR Lyrae stars

    NASA Astrophysics Data System (ADS)

    Hansen, C. J.; Nordström, B.; Bonifacio, P.; Spite, M.; Andersen, J.; Beers, T. C.; Cayrel, R.; Spite, F.; Molaro, P.; Barbuy, B.; Depagne, E.; François, P.; Hill, V.; Plez, B.; Sivarani, T.

    2011-03-01

    Context. The chemical composition of extremely metal-poor stars (EMP stars; [Fe/H] < ~ -3) is a unique tracer of early nucleosynthesis in the Galaxy. As such stars are rare, we wish to find classes of luminous stars which can be studied at high spectral resolution. Aims: We aim to determine the detailed chemical composition of the two EMP stars CS 30317-056 and CS 22881-039, originally thought to be red horizontal-branch (RHB) stars, and compare it to earlier results for EMP stars as well as to nucleosynthesis yields from various supernova (SN) models. In the analysis, we discovered that our targets are in fact the two most metal-poor RR Lyrae stars known. Methods: Our detailed abundance analysis, taking into account the variability of the stars, is based on VLT/UVES spectra (R ≃ 43 000) and 1D LTE OSMARCS model atmospheres and synthetic spectra. For comparison with SN models we also estimate NLTE corrections for a number of elements. Results: We derive LTE abundances for the 16 elements O, Na, Mg, Al, Si, S, Ca, Sc, Ti, Cr, Mn, Fe, Co, Ni, Sr and Ba, in good agreement with earlier values for EMP dwarf, giant and RHB stars. Li and C are not detected in either star. NLTE abundance corrections are newly calculated for O and Mg and taken from the literature for other elements. The resulting abundance pattern is best matched by model yields for supernova explosions with high energy and/or significant asphericity effects. Conclusions: Our results indicate that, except for Li and C, the surface composition of EMP RR Lyr stars is not significantly affected by mass loss, mixing or diffusion processes; hence, EMP RR Lyr stars should also be useful tracers of the chemical evolution of the early Galactic halo. The observed abundance ratios indicate that these stars were born from an ISM polluted by energetic, massive (25-40 M⊙) and /or aspherical supernovae, but the NLTE corrections for Sc and certain other elements do play a role in the choice of model. Based on

  17. Chemical abundances in a high-velocity RR Lyrae star near the bulge

    NASA Astrophysics Data System (ADS)

    Hansen, C. J.; Rich, R. M.; Koch, A.; Xu, S.; Kunder, A.; Ludwig, H.-G.

    2016-05-01

    Low-mass variable high-velocity stars are interesting study cases for many aspects of Galactic structure and evolution. Until recently, the only known high- or hyper-velocity stars were young stars thought to originate from the Galactic center. Wide-area surveys such as APOGEE and BRAVA have found several low-mass stars in the bulge with Galactic rest-frame velocities higher than 350 km s-1. In this study we present the first abundance analysis of a low-mass RR Lyrae star that is located close to the Galactic bulge, with a space motion of ~-400 km s-1. Using medium-resolution spectra, we derived abundances (including upper limits) of 11 elements. These allowed us to chemically tag the star and discuss its origin, although our derived abundances and metallicity, at [Fe/H] =-0.9 dex, do not point toward one unambiguous answer. Based on the chemical tagging, we cannot exclude that it originated in the bulge. However, its retrograde orbit and the derived abundances combined suggest that the star was accelerated from the outskirts of the inner (or even outer) halo during many-body interactions. Other possible origins include the bulge itself, or the star might have been stripped from a stellar cluster or the Sagittarius dwarf galaxy when it merged with the Milky Way. The data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation.

  18. WEAK GALACTIC HALO-DWARF SPHEROIDAL CONNECTION FROM RR LYRAE STARS

    SciTech Connect

    Fiorentino, Giuliana; Bono, Giuseppe; Monelli, Matteo; Gallart, Carme; Martínez-Vásquez, Clara E.; Tolstoy, Eline; Salaris, Maurizio; Bernard, Edouard J.

    2015-01-01

    We discuss the role that dwarf galaxies may have played in the formation of the Galactic halo (Halo) using RR Lyrae stars (RRL) as tracers of their ancient stellar component. The comparison is performed using two observables (periods, luminosity amplitudes) that are reddening and distance independent. Fundamental mode RRL in 6 dwarf spheroidals (dSphs) and 11 ultra faint dwarf galaxies (∼1300) show a Gaussian period distribution well peaked around a mean period of (Pab) = 0.610 ± 0.001 days (σ = 0.03). The Halo RRL (∼15,000) are characterized by a broader period distribution. The fundamental mode RRL in all the dSphs apart from Sagittarius are completely lacking in High Amplitude Short Period (HASP) variables, defined as those having P ≲ 0.48 days and A{sub V} ≥ 0.75 mag. Such variables are not uncommon in the Halo and among the globular clusters and massive dwarf irregulars. To further interpret this evidence, we considered 18 globulars covering a broad range in metallicity (–2.3 ≲ [Fe/H] ≲ –1.1) and hosting more than 35 RRL each. The metallicity turns out to be the main parameter, since only globulars more metal-rich than [Fe/H] ∼ –1.5 host RRL in the HASP region. This finding suggests that dSphs similar to the surviving ones do not appear to be the major building-blocks of the Halo. Leading physical arguments suggest an extreme upper limit of ∼50% to their contribution. On the other hand, massive dwarfs hosting an old population with a broad metallicity distribution (Large Magellanic Cloud, Sagittarius) may have played a primary role in the formation of the Halo.

  19. A SEARCH FOR RR LYRAE STARS IN SEGUE 2 AND SEGUE 3

    SciTech Connect

    Boettcher, Erin; Willman, Beth; Fadely, Ross; Baker, Mariah; Hopkins, Erica; Cunningham, Emily C.; Douglas, Tim; Gilbert, Jacob; Preston, Annie; Sturner, Andrew P.; Strader, Jay; Ananna, Tonima Tasnim E-mail: bwillman@haverford.edu

    2013-10-01

    We present an extensive search for RR Lyrae (RRL) stars in and around the ultra-faint Milky Way companions Segue 2 and Segue 3. The former (M{sub V} = –2.5) appears to be an extremely faint dwarf galaxy companion of the Milky Way. The latter (M{sub V} = 0.0) is among the faintest star clusters known. We use B and V band time-series imaging obtained at the WIYN 0.9 m telescope at Kitt Peak National Observatory to search for RRL in these objects. In our Segue 2 observations, we present a previously unknown fundamental mode (RRab) RRL star with a period of P {sub ab} = 0.748 days. With this measurement, we revisit the inverse correlation between (P {sub ab}) and ([Fe/H]) established in the literature for Milky Way dwarf galaxies and their RRL. In this context, the long period of Segue 2's RRab star as well as the known significant spread in metallicity in this dwarf galaxy are consistent with the observed trend in (P {sub ab}) and ([Fe/H]). We derive the first robust distance to Segue 2, using both its RRab star and spectroscopically confirmed blue horizontal branch stars. Using [Fe/H] = –2.16 and –2.44 dex, we find d{sub RRL}= 36.6{sup +2.5}{sub -2.4} and 37.7{sup +2.7}{sub -2.7} kpc; assuming [Fe/H] = –2.257 dex, we find d {sub BHB} = 34.4 ± 2.6 kpc. Although no RRL were present in the Segue 3 field, we found a candidate eclipsing binary star system.

  20. On a New Theoretical Framework for RR Lyrae Stars. I. The Metallicity Dependence

    NASA Astrophysics Data System (ADS)

    Marconi, M.; Coppola, G.; Bono, G.; Braga, V.; Pietrinferni, A.; Buonanno, R.; Castellani, M.; Musella, I.; Ripepi, V.; Stellingwerf, R. F.

    2015-07-01

    We present new nonlinear, time-dependent convective hydrodynamical models of RR Lyrae stars computed assuming a constant helium-to-metal enrichment ratio and a broad range in metal abundances (Z = 0.0001–0.02). The stellar masses and luminosities adopted to construct the pulsation models were fixed according to detailed central He-burning horizontal-branch evolutionary models. The pulsation models cover a broad range in stellar luminosity and effective temperatures and the modal stability is investigated for both fundamental (FU) and first overtone polsators (FOs). We predict the topology of the instability strip (IS) as a function of the metal content and new analytical relations for the edges of the IS in the observational plane. Moreover, a new analytical relation to constrain the pulsation mass of double pulsators as a function of the period ratio and the metal content is provided. We derive new Period–Radius–Metallicity relations for FU and FO pulsators. They agree quite well with similar empirical and theoretical relations in the literature. From the predicted bolometric light curves, transformed into optical (UBVRI) and near-infrared (NIR; JHK) bands, we compute the intensity-averaged mean magnitudes along the entire pulsation cycle and in turn new and homogenous metal-dependent (RIJHK) Period–Luminosity relations. Moreover, we compute new dual and triple-band optical, optical–NIR, and NIR Period–Wesenheit–Metallicity relations. Interestingly, we find that the optical Period-W(V, B–V) is independent of the metal content and that the accuracy of individual distances is a balance between the adopted diagnostics and the precision of photometric and spectroscopic data sets.

  1. Extending the Virgo Stellar Stream with SEKBO Survey RR Lyrae Stars

    NASA Astrophysics Data System (ADS)

    Prior, Sayuri L.; Da Costa, G. S.; Keller, Stefan C.; Murphy, Simon J.

    2009-01-01

    A subset of the RR Lyrae (RRL) candidates identified from the Southern Edgeworth-Kuiper Belt Object (SEKBO) survey data have been followed up photometrically (n = 106) and spectroscopically (n = 51). Period and light curve fitting reveals a 24% ± 7% contamination of SEKBO survey data by non-RRLs. This paper focuses on the region of the Virgo Stellar Stream (VSS), particularly on its extension to the south of the declination limits of the Sloan Digital Sky Survey and of the Quasar Equatorial Survey Team RRL survey. The distribution of radial velocities in the Galactic standard of rest frame (V GSR) for the 11 RRLs observed in the VSS region has two apparent peaks. The larger peak coincides with the four RRLs having langV GSRrang = 127 ± 10 km s-1 and dispersion σ = 27 km s-1, marginally larger than that expected from the errors alone. The two type ab RRLs in this group have lang[Fe/H]rang = -1.95 ± 0.1. Both the radial velocities and metal abundances are consistent with membership in the VSS. The second velocity peak, which occurs at langV GSRrang = -175 ± 10 km s-1 may indicate the presence of stars from the Sgr leading tidal tail, which is expected to have large negative velocities in this region. We explore the spatial extent of the VSS by constructing luminosity functions from the SEKBO data and comparing them to data synthesized with the Besançon Galactic model. Analysis of the excess over the model predictions reveals the VSS as a large (~760 deg2) overdensity centered at roughly (R.A., decl.) ~ (186°, -4°), spanning a length of ~15 kpc in projection, assuming a heliocentric distance of 19 kpc. The data reveal for the first time the more southern regions of the stream and trace it to decl. ≈-15° and Galactic latitudes as low as b ≈ 45°.

  2. RR Lyrae in XSTPS: The halo density profile in the north galactic cap

    SciTech Connect

    Faccioli, L.; Smith, M. C.; Yuan, H.-B.; Liu, X.-W.; Zhang, H.-H.; Zhao, H.-B.; Yao, J.-S. E-mail: msmith@shao.ac.cn

    2014-06-20

    We present a catalog of RR Lyrae stars (RRLs) observed by the Xuyi Schmidt Telescope Photometric Survey (XSTPS). The area we consider is located in the north Galactic cap, covering ≈376.75 deg{sup 2} at α ≈ 150° and δ ≈ 27° down to a magnitude limit of i ≈ 19. Using the variability information afforded by the multi-epoch nature of our XSTPS data, combined with colors from the Sloan Digital Sky Survey, we are able to identify candidate RRLs. We find 318 candidates, derive distances to them, and estimate the detection efficiency. The majority of our candidates have more than 12 observations, and for these we are able to calculate periods. These also allow us to estimate our contamination level, which we predict is between 30% and 40%. Finally, we use the sample to probe the halo density profile in the 9-49 kpc range and find that it can be well fitted by a double power law. We find good agreement between this model and the models derived for the south Galactic cap using the Watkins et al. and Sesar et al. RRL data sets, after accounting for possible contamination in our data set from Sagittarius stream members. We consider non-spherical double power-law models of the halo density profile and again find agreement with literature data sets, although we have limited power to constrain the flattening due to our small survey area. Much tighter constraints will be placed by current and future wide-area surveys, most notably ESA's astrometric Gaia mission. Our analysis demonstrates that surveys with a limited number of epochs can effectively be mined for RRLs. Our complete sample is provided as accompanying online material; as an example the first few entries of each electronic table are shown in the text.

  3. PROBING THE OUTER GALACTIC HALO WITH RR LYRAE FROM THE CATALINA SURVEYS

    SciTech Connect

    Drake, A. J.; Djorgovski, S. G.; Graham, M. J.; Mahabal, A.; Donalek, C.; Williams, R.; Catelan, M.; Torrealba, G.; Belokurov, V.; Koposov, S. E.; Prieto, J. L.; Larson, S.; Christensen, E.; Beshore, E.

    2013-01-20

    We present analysis of 12,227 type-ab RR Lyraes (RRLs) found among the 200 million public light curves in Catalina Surveys Data Release 1. These stars span the largest volume of the Milky Way ever surveyed with RRLs, covering {approx}20,000 deg{sup 2} of the sky (0 Degree-Sign < {alpha} < 360 Degree-Sign , -22 Degree-Sign < {delta} < 65 Degree-Sign ) to heliocentric distances of up to 60 kpc. Each of the RRLs is observed between 60 and 419 times over a six-year period. Using period finding and Fourier fitting techniques we determine periods and apparent magnitudes for each source. We find that the periods are generally accurate to {sigma} = 0.002% in comparison to 2842 previously known RRLs and 100 RRLs observed in overlapping survey fields. We photometrically calibrate the light curves using 445 Landolt standard stars and show that the resulting magnitudes are accurate to {approx}0.05 mag using Sloan Digital Sky Survey (SDSS) data for {approx}1000 blue horizontal branch stars and 7788 RRLs. By combining Catalina photometry with SDSS spectroscopy, we analyze the radial velocity and metallicity distributions for >1500 of the RRLs. Using the accurate distances derived for the RRLs, we show the paths of the Sagittarius tidal streams crossing the sky at heliocentric distances from 20 to 60 kpc. By selecting samples of Galactic halo RRLs, we compare their velocity, metallicity, and distance with predictions from a recent detailed N-body model of the Sagittarius system. We find that there are some significant differences between the distances and structures predicted and our observations.

  4. RR Lyrae in XSTPS: The Halo Density Profile in the North Galactic Cap

    NASA Astrophysics Data System (ADS)

    Faccioli, L.; Smith, M. C.; Yuan, H.-B.; Zhang, H.-H.; Liu, X.-W.; Zhao, H.-B.; Yao, J.-S.

    2014-06-01

    We present a catalog of RR Lyrae stars (RRLs) observed by the Xuyi Schmidt Telescope Photometric Survey (XSTPS). The area we consider is located in the north Galactic cap, covering ≈376.75 deg2 at α ≈ 150° and δ ≈ 27° down to a magnitude limit of i ≈ 19. Using the variability information afforded by the multi-epoch nature of our XSTPS data, combined with colors from the Sloan Digital Sky Survey, we are able to identify candidate RRLs. We find 318 candidates, derive distances to them, and estimate the detection efficiency. The majority of our candidates have more than 12 observations, and for these we are able to calculate periods. These also allow us to estimate our contamination level, which we predict is between 30% and 40%. Finally, we use the sample to probe the halo density profile in the 9-49 kpc range and find that it can be well fitted by a double power law. We find good agreement between this model and the models derived for the south Galactic cap using the Watkins et al. and Sesar et al. RRL data sets, after accounting for possible contamination in our data set from Sagittarius stream members. We consider non-spherical double power-law models of the halo density profile and again find agreement with literature data sets, although we have limited power to constrain the flattening due to our small survey area. Much tighter constraints will be placed by current and future wide-area surveys, most notably ESA's astrometric Gaia mission. Our analysis demonstrates that surveys with a limited number of epochs can effectively be mined for RRLs. Our complete sample is provided as accompanying online material; as an example the first few entries of each electronic table are shown in the text.

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

    SciTech Connect

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

    2013-08-20

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

  6. GSC 03529-02286, GSC 02008-00283 und GSC 07165-03037 - Drei neue RR-Lyrae-Sterne

    NASA Astrophysics Data System (ADS)

    Bernhard, Klaus; Srdoc, Gregor; Huemmerich, Stefan

    2013-03-01

    During an extended investigation of candidate variable stars from the SuperWASP database (cf. e.g. Bernhard and Srdoc, 2011), three new RR Lyrae stars have been discovered. The following elements have been derived: GSC 03529-02286 (Type RRc): HJD (Max) = 2454327.472 (4) + E* 0.277202 (2) GSC 02008-00283 (Type RRc): HJD (Max) = 2453567.669 (2) + E* 0.349129 (2) GSC 07165-03037 (Type RRab): HJD (Max) = 2453901.869 (2) + E* 0.561553 (2) Klaus Bernhard and Stefan Huemmerich are member of the BAV.

  7. Near-Field Cosmology with RR Lyrae Variable Stars: A First View of Substructure in the Southern Sky

    NASA Astrophysics Data System (ADS)

    Navarrete, C.; Duffau, S.; Vivas, A. K.; Catelan, M.; Hajdu, G.; Torrealba, G.; Cortés, C.; Belokurov, V.; Koposov, S.; Drake, A. J.

    2016-08-01

    We present the current status of the spectroscopic follow-up of a large number of RR Lyrae (RRL) halo overdensity candidates recently found by Torrealba et al. (2015) using southern-hemisphere data from the Catalina Real-time Transient Survey (CRTS). Characterizing the individual RRL stars in these overdensities is crucial to confirm them as real halo substructures. Low-resolution spectra have been obtained for RRL stars in 11 different overdensities, using the SOAR and Magellan telescopes. Radial velocities and metallicities have been derived so far for 123 and 99 RRL stars, respectively.

  8. Observing RR Lyrae Variables in the M3 Globular Cluster with the BYU West Mountain Observatory (Abstract)

    NASA Astrophysics Data System (ADS)

    Joner, M. D.

    2016-06-01

    (Abstract only) We have utilized the 0.9-meter telescope of the Brigham Young University West Mountain Observatory to secure data on the northern hemisphere globular cluster NGC 5272 (M3). We made 216 observations in the V filter spaced between March and August 2012. We present light curves of the M3 RR Lyrae stars using different techniques. We compare light curves produced using DAOPHOT and ISIS software packages for stars in both the halo and core regions of this globular cluster. The light curve fitting is done using FITLC.

  9. Finding, characterizing and classifying variable sources in multi-epoch sky surveys: QSOs and RR Lyraes in PS1 3Pi

    NASA Astrophysics Data System (ADS)

    Hernitschek, N.; Schlafly, E. F.; Sesar, B.; Rix, H.-W.; Hogg, D. W.; Ivezic, Z.; Grebel, E. K.

    2016-05-01

    We develop a new approach for quantifying statistical properties of non-simultaneous, sparse, multi-color light curves through light-curve structure functions. Using PS1 data on SDSS Stripe 82 as "ground truth", a Random Forest Classifier identifies QSOs and RR Lyrae stars based on their variability and mean PS1 and WISE colors. We find that, aside from the Galactic plane, QSO and RR Lyrae samples of purity 75% and completeness 92% can be selected. On this completeness and purity basis we have identified a QSO candidate sample of a million objects, including many at low latitudes. We have assembled an unprecedentedly large and deep sample of 150 000 likely RR Lyrae candidates, with distances from 10 kpc to 120 kpc. We provide a catalog of 2.6 x 107 likely variable point sources. This work illustrates the power of time- domain surveys to identify variable objects and opens up enormous follow-up possibilities.

  10. TIME-SERIES PHOTOMETRY OF GLOBULAR CLUSTERS: M62 (NGC 6266), THE MOST RR LYRAE-RICH GLOBULAR CLUSTER IN THE GALAXY?

    SciTech Connect

    Contreras, R.; Catelan, M.; Smith, H. A.; Kuehn, C. A.; Pritzl, B. J.; Borissova, J.

    2010-12-15

    We present new time-series CCD photometry, in the B and V bands, for the moderately metal-rich ([Fe/H] {approx_equal} -1.3) Galactic globular cluster M62 (NGC 6266). The present data set is the largest obtained so far for this cluster and consists of 168 images per filter, obtained with the Warsaw 1.3 m telescope at the Las Campanas Observatory and the 1.3 m telescope of the Cerro Tololo Inter-American Observatory, in two separate runs over the time span of 3 months. The procedure adopted to detect the variable stars was the optimal image subtraction method (ISIS v2.2), as implemented by Alard. The photometry was performed using both ISIS and Stetson's DAOPHOT/ALLFRAME package. We have identified 245 variable stars in the cluster fields that have been analyzed so far, of which 179 are new discoveries. Of these variables, 133 are fundamental mode RR Lyrae stars (RRab), 76 are first overtone (RRc) pulsators, 4 are type II Cepheids, 25 are long-period variables (LPVs), 1 is an eclipsing binary, and 6 are not yet well classified. Such a large number of RR Lyrae stars places M62 among the top two most RR Lyrae-rich (in the sense of total number of RR Lyrae stars present) globular clusters known in the Galaxy, second only to M3 (NGC 5272) with a total of 230 known RR Lyrae stars. Since this study covers most but not all of the cluster area, it is not unlikely that M62 is in fact the most RR Lyrae-rich globular cluster in the Galaxy. In like vein, thanks to the time coverage of our data sets, we were also able to detect the largest sample of LPVs known so far in a Galactic globular cluster. We analyze a variety of Oosterhoff type indicators for the cluster, including mean periods, period distribution, Bailey diagrams, and Fourier decomposition parameters (as well as the physical parameters derived therefrom). All of these indicators clearly show that M62 is an Oosterhoff type I system. This is in good agreement with the moderately high metallicity of the cluster, in spite

  11. Metallic Line Doubling and van hoof Effect in the Spectra of the Variable Star RR Lyrae

    NASA Astrophysics Data System (ADS)

    Sefyani Lakrizi, Fouad; Benhida, Abdelmjid; Gillet, Denis; Mathias, phillipe; de France, Thibault; Benkhaldoun, Zouhair; Lazrek, Mohamed; Daassou, Ahmed

    2015-08-01

    The Oukaïmeden observatory is situated at an altitude of 2700m in the High Atlas mountain range, 78km south of Marrakech 7°52’52’’ west and 31°12’32’’ north. The quality of the sky is considered exceptional, not only for imaging but also for photometry. Indeed, the average measured seeing is of the order of 1 arc second which ensures high quality spectrum recording with a good signal-to-noise ratio. In this communication, we will present our observations of the phenomenon of metallic absorption lines, doubling in the spectra of the variable star RR Lyrae on Fe II (l4923.921 Å), as well as of sodium D lines. In emission, we observed the lines of hydrogen Hα, Hβ and Hγ with a very strong intensity (50 % above the continuum). We also observed the Van Hoof effect which consists of a difference between the radial velocity of the line of the Fe II (λ4923.921 Å) and that of the line Hβ. These observations were carried out with a small spectrograph of approximately 12000 resolution, installed on a 14 inch telescope, during the night of October 12th 2013. This date corresponded to the maximal phase of the Blazhko cycle. The doubling of the lines was interpreted by Schwarzschild on the basis of an atmosphere in two layers. Based on this interpretation we were able to measure the radial velocity of the shock wave deducted from the difference between both red and blue spectral components on the lines Hα of hydrogen, D of the sodium and the Fe II during the doubling of observed lines. The shock wave reached the maximal speed of 160 kms-1 so confirming the hypersonic regime to which atmosphere is submitted during this maximum phase of the Blazhko cycle. We will also present a comparison of our results with those obtained with high resolution spectrographs and thus confirm the validity of our results.

  12. Variaciones seculares de período en las RR Lyrae de ω~Centauri

    NASA Astrophysics Data System (ADS)

    Marraco, H. G.; Milesi, G. E.

    Utilizando 689 observaciones de 35 estrellas RR Lyrae del cúmulo globular ω Centauri hemos obtenido nuevas determinaciones de sus períodos y sus correspondientes variaciones seculares. Las observaciones fueron obtenidas de la literatura con la excepción de un grupo 66 determinaciones que se presentan por vez primera aquí. Utilizando el parámetro testigo σ descripto en Marraco & Muzzio (Publ. Astron. Soc. Pacific 92, 700, 1980), hemos realizado un ajuste bidimensional en P y β (donde β es la variación secular del período). Con este fin la totalidad de las 689 observaciones fueron llevadas a un sistema fotométrico común. Para esto se realizó un cuidadoso análisis de los numerosos errores en la identificación de las estrellas de las series de comparación. Los resultados de los ajustes bidimensionales fueron analizados utilizando técnicas de procesamiento de imágenes. Con este fin el parámetro de ajuste σ fue representado como función de P y β. En las imágenes resultantes se buscaron los mínimos y al menor de ellos se lo aceptó como período instantáneo verdadero y su variación secular β. La determinación precisa de cada parámetro se realizó mediante ajuste de gaussianas y se determinaron sus errores. A modo de ejemplo la variable #8 fue analizada en una matriz de 501 × 501 elementos representando el parámetro σ para valores comprendidos entre 0,521034 < P < 0,521534 dias y -150×10-10 < β < +150×10-10 dias/dia. El mejor período instantáneo (correspondiente a la época DJ=2.426.908) y su variación secular son P = 0,5212859±0,0000001 días y β 14,012±,010×10-10 días/día respectivamente. Con estos valores el parámetro testigo resulta σ= 0,127 . Si no se tiene en cuenta la variación secular del período y se busca aquél de mejor ajuste para β = 0, se obtiene P = 0,5212960 días, pero entonces el parámetro de ajuste resulta tan alto como σ = 0,23 .

  13. Near-Field Cosmology with RR Lyrae Variable Stars: A first view of substructure in the Southern Sky

    NASA Astrophysics Data System (ADS)

    Navarrete, Camila; Duffau, Sonia; Catelan, Márcio; Vivas, Anna Katherina; Hajdu, Gergely; Torrealba, Gabriel

    2015-08-01

    The arrival of the SDSS revealed that the northern-hemisphere halo has plenty of substructures (e.g., the Field of Streams; Belokurov et al. 2006). The southern-hemisphere sky, on the other hand, remains a "terra incognita" where only recently some substructure candidates have been found, thanks to ongoing wide-field surveys. Extending the census of halo overdensities to the southern sky is important as these structures provide clues into the Milky Way's merger history. Very recently, more than 20 southern overdensity candidates were found, using RR Lyrae data from the Catalina Real-time Transient Survey (Torrealba et al, 2015). However, the confirmation of those RR Lyrae overdensities as remnants of protogalactic fragments that may have helped build the present-day Galactic halo requires spectroscopic confirmation, in order to distinguish, using radial velocities and chemical information alike, bona-fide overdensities from random clumping among halo field stars. In this contribution, we will present preliminary results of a spectroscopic follow-up of several of the Torrealba et al. southern overdensity candidates, based on low-resolution spectra obtained with the SOAR and Magellan telescopes.

  14. THE OPTICAL GRAVITATIONAL LENSING EXPERIMENT: ANALYSIS OF THE BULGE RR LYRAE POPULATION FROM THE OGLE-III DATA

    SciTech Connect

    Pietrukowicz, P.; Udalski, A.; Soszynski, I.; Wyrzykowski, L.; Poleski, R.; Kozlowski, S.; Szymanski, M. K.; Kubiak, M.; Pietrzynski, G.; Ulaczyk, K.; Nataf, D. M.

    2012-05-10

    We have analyzed the data on 16,836 RR Lyrae (RR Lyr) variables observed toward the Galactic bulge during the third phase of the Optical Gravitational Lensing Experiment (OGLE-III), which took place in 2001-2009. Using these standard candles, we show that the ratio of total-to-selective extinction toward the bulge is given by R{sub I} = A{sub I} /E(V - I) = 1.080 {+-} 0.007 and is independent of color. We demonstrate that the bulge RR Lyr stars form a metal-uniform population, slightly elongated in its inner part. The photometrically derived metallicity distribution is sharply peaked at [Fe/H] = -1.02 {+-} 0.18, with a dispersion of 0.25 dex. In the inner regions (|l| < 3 Degree-Sign , |b| < 4 Degree-Sign ) the RR Lyr tend to follow the barred distribution of the bulge red clump giants. The distance to the Milky Way center inferred from the bulge RR Lyr is R{sub 0} = 8.54 {+-} 0.42 kpc. We report a break in the mean density distribution at a distance of {approx}0.5 kpc from the center indicating its likely flattening. Using the OGLE-III data, we assess that (4-7) Multiplication-Sign 10{sup 4} type ab RR Lyr variables should be detected toward the bulge area of the ongoing near-IR VISTA Variables in the Via Lactea (VVV) survey, where the uncertainty partially results from the unknown RR Lyr spatial density distribution within 0.2 kpc from the Galactic center.

  15. EXPLORING THE VARIABLE SKY WITH LINEAR. II. HALO STRUCTURE AND SUBSTRUCTURE TRACED BY RR LYRAE STARS TO 30 kpc

    SciTech Connect

    Sesar, Branimir; Ivezic, Zeljko; Morgan, Dylan M.; Becker, Andrew C.; Stuart, J. Scott; Sharma, Sanjib; Palaversa, Lovro; Juric, Mario; Wozniak, Przemyslaw; Oluseyi, Hakeem

    2013-08-01

    We present a sample of {approx}5000 RR Lyrae stars selected from the recalibrated LINEAR data set and detected at heliocentric distances between 5 kpc and 30 kpc over {approx}8000 deg{sup 2} of sky. The coordinates and light curve properties, such as period and Oosterhoff type, are made publicly available. We analyze in detail the light curve properties and Galactic distribution of the subset of {approx}4000 type ab RR Lyrae (RRab) stars, including a search for new halo substructures and the number density distribution as a function of Oosterhoff type. We find evidence for the Oosterhoff dichotomy among field RR Lyrae stars, with the ratio of the type II and I subsamples of about 1:4, but with a weaker separation than for globular cluster stars. The wide sky coverage and depth of this sample allow unique constraints for the number density distribution of halo RRab stars as a function of galactocentric distance: it can be described as an oblate ellipsoid with an axis ratio q = 0.63 and with either a single or a double power law with a power-law index in the range -2 to -3. Consistent with previous studies, we find that the Oosterhoff type II subsample has a steeper number density profile than the Oosterhoff type I subsample. Using the group-finding algorithm EnLink, we detected seven candidate halo groups, only one of which is statistically spurious. Three of these groups are near globular clusters (M53/NGC 5053, M3, M13), and one is near a known halo substructure (Virgo Stellar Stream); the remaining three groups do not seem to be near any known halo substructures or globular clusters and seem to have a higher ratio of Oosterhoff type II to Oosterhoff type I RRab stars than what is found in the halo. The extended morphology and the position (outside the tidal radius) of some of the groups near globular clusters are suggestive of tidal streams possibly originating from globular clusters. Spectroscopic follow-up of detected halo groups is encouraged.

  16. Metal Abundances, Radial Velocities, and Other Physical Characteristics for the RR Lyrae Stars in The Kepler Field

    NASA Astrophysics Data System (ADS)

    Nemec, James M.; Cohen, Judith G.; Ripepi, Vincenzo; Derekas, Aliz; Moskalik, Pawel; Sesar, Branimir; Chadid, Merieme; Bruntt, Hans

    2013-08-01

    Spectroscopic iron-to-hydrogen ratios, radial velocities, atmospheric parameters, and new photometric analyses are presented for 41 RR Lyrae stars (and one probable high-amplitude δ Sct star) located in the field-of-view of the Kepler space telescope. Thirty-seven of the RR Lyrae stars are fundamental-mode pulsators (i.e., RRab stars) of which sixteen exhibit the Blazhko effect. Four of the stars are multiperiodic RRc pulsators oscillating primarily in the first-overtone mode. Spectroscopic [Fe/H] values for the 34 stars for which we were able to derive estimates range from -2.54 ± 0.13 (NR Lyr) to -0.05 ± 0.13 dex (V784 Cyg), and for the 19 Kepler-field non-Blazhko stars studied by Nemec et al. the abundances agree will with their photometric [Fe/H] values. Four non-Blazhko RR Lyrae stars that they identified as metal-rich (KIC 6100702, V2470 Cyg, V782 Cyg and V784 Cyg) are confirmed as such, and four additional stars (V839 Cyg, KIC 5520878, KIC 8832417, KIC 3868420) are also shown here to be metal-rich. Five of the non-Blazhko RRab stars are found to be more metal-rich than [Fe/H] ~-0.9 dex while all of the 16 Blazhko stars are more metal-poor than this value. New P-\\phi _31^s-[Fe/H] relationships are derived based on ~970 days of quasi-continuous high-precision Q0-Q11 long- and short-cadence Kepler photometry. With the exception of some Blazhko stars, the spectroscopic and photometric [Fe/H] values are in good agreement. Several stars with unique photometric characteristics are identified, including a Blazhko variable with the smallest known amplitude and frequency modulations (V838 Cyg). Based in part on observations made at the W.M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California and the National Aeronautics and Space Administration. The Keck Observatory was made possible by the generous financial support of the W.M. Keck Foundation. Also, based in part on

  17. Pulsations and period changes of the non-Blazhko RR lyrae variable Y oct observed from Dome A, Antarctica

    SciTech Connect

    Zhihua, Huang; Jianning, Fu; Weikai, Zong; Lingzhi, Wang; Zonghong, Zhu; M, Macri Lucas; Lifan, Wang; Ashley, Michael C. B.; S, Lawrence Jon; Daniel, Luong-Van; Xiangqun, Cui; Long-Long, Feng; Xuefei, Gong; Qiang, Liu; Huigen, Yang; Xiangyan, Yuan; Xu, Zhou; Zhenxi, Zhu; R, Pennypacker Carl; G, York Donald

    2015-01-01

    During the operation of the Chinese Small Telescope Array (CSTAR) in Dome A of Antarctica in the years 2008, 2009, and 2010, large amounts of photometric data have been obtained for variable stars in the CSTAR field. We present here the study of one of six RR Lyrae variables, Y Oct, observed with CSTAR in Dome A, Antarctica. Photometric data in the i band were obtained in 2008 and 2010, with a duty cycle (defined as the fraction of time representing scientifically available data to CSTAR observation time) of about 44% and 52%, respectively. In 2009, photometric data in the g and r bands were gathered for this star, with a duty cycle of 65% and 60%, respectively. Fourier analysis of the data in the three bands only shows the fundamental frequency and its harmonics, which is characteristic of the non-Blazhko RR Lyrae variables. Values of the fundamental frequency and the amplitudes, as well as the total pulsation amplitude, are obtained from the data in the three bands separately. The amplitude of the fundamental frequency and the total pulsation amplitude in the g band are the largest, and those in the i band the smallest. Two-hundred fifty-one times of maximum are obtained from the three seasons of data, which are analyzed together with 38 maximum times provided in the GEOS RR Lyrae database. A period change rate of −0.96 ± 0.07 days Myr{sup −1} is then obtained, which is a surprisingly large negative value. Based on relations available in the literature, the following physical parameters are derived: [Fe/H] = −1.41 ± 0.14, M{sub V} = 0.696 ± 0.014 mag, V−K = 1.182 ± 0.028 mag, logT{sub eff} = 3.802 ± 0.003 K, logg = 2.705 ± 0.004, logL/L{sub ⊙} = 1.625 ± 0.013, and logM/M{sub ⊙} = −0.240 ± 0.019.

  18. VizieR Online Data Catalog: 33 RR Lyrae observed in Pisces with K2-E2 (Molnar+, 2015)

    NASA Astrophysics Data System (ADS)

    Molnar, L.; Szabo, R.; Moskalik, P. A.; Nemec, J. M.; Guggenberger, E.; Smolec, R.; Poleski, R.; Plachy, E.; Kolenberg, K.; Kollath, Z.

    2016-03-01

    Kepler observed a stellar field around the vernal equinox point in Pisces (centre coordinates: RA=359°, DE=-2°) between 2014 February 04 and 13. The primary goal of this K2 Two-Wheel Concept Engineering Test (hereafter K2-E2) was to test the performance of the telescope in fine guidance mode. As well, the observations of nearly 2000 targets were made available for the scientific community. We identified 33 potential RR Lyrae stars in the K2-E2 sample and extracted their photometric data with the pyke software, developed for the Kepler mission by the Kepler Guest Observer Office (Still & Barclay, 2012, Astrophysics Source Code Library record ascl:1208.004). (6 data files).

  19. ANCIENT STARS BEYOND THE LOCAL GROUP: RR LYRAE VARIABLES AND BLUE HORIZONTAL BRANCH STARS IN SCULPTOR GROUP DWARF GALAXIES

    SciTech Connect

    Da Costa, G. S.; Jerjen, H.; Rejkuba, M.; Grebel, E. K.

    2010-01-10

    We have used Hubble Space Telescope Advanced Camera for Surveys images to generate color-magnitude diagrams that reach below the magnitude of the horizontal branch in the Sculptor Group dwarf galaxies ESO294-010 and ESO410-005. In both diagrams, blue horizontal branch stars are unambiguously present, a signature of the existence of an ancient stellar population whose age is comparable to that of the Galactic halo globular clusters. The result is reinforced by the discovery of numerous RR Lyrae variables in both galaxies. The occurrence of these stars is the first direct confirmation of the existence of ancient stellar populations beyond the Local Group and indicates that star formation can occur at the earliest epochs even in low-density environments.

  20. The Interstellar Extinction Towards the Milky Way Bulge with Planetary Nebulae, Red Clump, and RR Lyrae Stars

    NASA Astrophysics Data System (ADS)

    Nataf, David M.

    2016-06-01

    I review the literature covering the issue of interstellar extinction towards the Milky Way bulge, with emphasis placed on findings from planetary nebulae, RR Lyrae, and red clump stars. I also report on observations from HI gas and globular clusters. I show that there has been substantial progress in this field in recent decades, most particularly from red clump stars. The spatial coverage of extinction maps has increased by a factor ~ 100 × in the past 20 yr, and the total-to-selective extinction ratios reported have shifted by ~ 20-25%, indicative of the improved accuracy and separately, of a steeper-than-standard extinction curve. Problems remain in modelling differential extinction, explaining anomalies involving the planetary nebulae, and understanding the difference between bulge extinction coefficients and `standard' literature values.

  1. Cyclic variations in O-C diagrams of field RR Lyrae stars as a result of LiTE

    NASA Astrophysics Data System (ADS)

    Liška, J.; Skarka, M.; Zejda, M.; Mikulášek, Z.; de Villiers, S. N.

    2016-04-01

    This paper presents an extensive overview of known and proposed RR Lyrae stars in binaries. The aim is to revise and extend the list with new Galactic field systems. We utilized maxima timings for eleven RRab type stars with suspicious behaviour from the GEOS database, and determined maxima timings from data of sky surveys and our own observations. This significantly extended the number of suitable maxima timings. We modelled the proposed Light Time Effect (LiTE) in O-C diagrams to determine orbital parameters for these systems. In contrast to recent studies, our analysis focused on decades-long periods instead of periods in the order of years. Secondary components were found to be predominantly low-mass objects. However, for RZ Cet and AT Ser the mass of the suspected companion of more than one solar mass suggests that it is a massive white dwarf, a neutron star or even a black hole. We found that the semi-major axes of the proposed orbits are between 1 and 20 au. Because the studied stars belong to the closest RR Lyraes, maximal angular distances between components during orbit should at least be between 1 and 13 mas and this improves the chance to detect both stars using current telescopes. However, our interpretation of the O-C diagrams as a consequence of the LiTE should be considered as preliminary without reliable spectroscopic measurements. On the other hand our models give a prediction of the period and radial velocity evolution which should be sufficient for plausible proof of binarity.

  2. Cyclic variations in O-C diagrams of field RR Lyrae stars as a result of LiTE

    NASA Astrophysics Data System (ADS)

    Liška, J.; Skarka, M.; Zejda, M.; Mikulášek, Z.; de Villiers, S. N.

    2016-07-01

    This paper presents an extensive overview of known and proposed RR Lyrae stars in binaries. The aim is to revise and extend the list with new Galactic field systems. We utilized maxima timings for 11 RRab type stars with suspicious behaviour from the GEOS data base, and determined maxima timings from data of sky surveys and our own observations. This significantly extended the number of suitable maxima timings. We modelled the proposed Light Time Effect (LiTE) in O-C diagrams to determine orbital parameters for these systems. In contrast to recent studies, our analysis focused on decades-long periods instead of periods in the order of years. Secondary components were found to be predominantly low-mass objects. However, for RZ Cet and AT Ser the mass of the suspected companion of more than one solar mass suggests that it is a massive white dwarf, a neutron star or even a black hole. We found that the semimajor axes of the proposed orbits are between 1 and 20 au. Because the studied stars belong to the closest RR Lyraes, maximal angular distances between components during orbit should at least be between 1 and 13 mas and this improves the chance to detect both stars using current telescopes. However, our interpretation of the O-C diagrams as a consequence of the LiTE should be considered as preliminary without reliable spectroscopic measurements. On the other hand, our models give a prediction of the period and radial velocity evolution which should be sufficient for plausible proof of binarity.

  3. MID-INFRARED PERIOD-LUMINOSITY RELATIONS OF RR LYRAE STARS DERIVED FROM THE WISE PRELIMINARY DATA RELEASE

    SciTech Connect

    Klein, Christopher R.; Bloom, Joshua S.; Richards, Joseph W.; Butler, Nathaniel R. E-mail: jwrichar@stat.berkeley.edu E-mail: jbloom@astro.berkeley.edu

    2011-09-10

    Interstellar dust presents a significant challenge to extending parallax-determined distances of optically observed pulsational variables to larger volumes. Distance ladder work at mid-infrared wavebands, where dust effects are negligible and metallicity correlations are minimized, has been largely focused on few-epoch Cepheid studies. Here we present the first determination of mid-infrared period-luminosity (PL) relations of RR Lyrae stars from phase-resolved imaging using the preliminary data release of the Wide-field Infrared Survey Explorer (WISE). We present a novel statistical framework to predict posterior distances of 76 well observed RR Lyrae that uses the optically constructed prior distance moduli while simultaneously imposing a power-law PL relation to WISE-determined mean magnitudes. We find that the absolute magnitude in the bluest WISE filter is M{sub W1} = (- 0.421 {+-} 0.014) - (1.681 {+-} 0.147)log{sub 10}(P/0.50118 day), with no evidence for a correlation with metallicity. Combining the results from the three bluest WISE filters, we find that a typical star in our sample has a distance measurement uncertainty of 0.97% (statistical) plus 1.17% (systematic). We do not fundamentalize the periods of RRc stars to improve their fit to the relations. Taking the Hipparcos-derived mean V-band magnitudes, we use the distance posteriors to determine a new optical metallicity-luminosity relation. The results of this analysis will soon be tested by Hubble Space Telescope parallax measurements and, eventually, with the GAIA astrometric mission.

  4. Optical and Near-Infrared UBVRIJHK Photometry for the RR Lyrae Stars in the Nearby Globular Cluster M4 (NGC 6121)

    NASA Astrophysics Data System (ADS)

    Stetson, P. B.; Braga, V. F.; Dall'Ora, M.; Bono, G.; Buonanno, R.; Ferraro, I.; Iannicola, G.; Marengo, M.; Neeley, J.

    2014-06-01

    We present optical and near-infrared UBVRIJHK photometry of stars in the Galactic globular cluster M4 (NGC 6121) based upon a large corpus of observations obtained mainly from public astronomical archives. We concentrate on the RR Lyrae variable stars in the cluster, and make a particular effort to accurately reidentify the previously discovered variables. We have also discovered two new probable RR Lyrae variables in the M4 field: one of them by its position on the sky and its photometric properties is a probable member of the cluster, and the second is a probable background (bulge?) object. We provide accurate equatorial coordinates for all 47 stars identified as RR Lyraes, new photometric measurements for 46 of them, and new period estimates for 45. We have also derived accurate positions and mean photometry for 34 more stars previously identified as variable stars of other types, and for an additional five non-RR Lyrae variable stars identified for the first time here. We present optical and near-infrared color-magnitude diagrams for the cluster and show the locations of the variable stars in them. We present the Bailey (period-amplitude) diagrams and the period-frequency histogram for the RR Lyrae stars in M4 and compare them to the corresponding diagrams for M5 (NGC 5904). We conclude that the RR Lyrae populations in the two clusters are quite similar in all the relevant properties that we have considered. The mean periods, pulsation-mode ratios, and Bailey diagrams of these two clusters show support for the recently proposed "Oosterhoff-neutral" classification. Based in part on data obtained from the ESO Science Archive Facility under multiple requests by the authors; in part on data obtained from the Isaac Newton Group Archive, which is maintained as part of the CASU Astronomical Data Centre at the Institute of Astronomy, Cambridge; and in part upon data distributed by the NOAO Science Archive. NOAO is operated by the Association of Universities for

  5. HST/WFPC2 imaging of the dwarf satellites And XI and And XIII: horizontal branch morphology and RR Lyraes

    NASA Astrophysics Data System (ADS)

    Yang, S.-C.; Sarajedini, A.

    2012-01-01

    We present a study of the stellar populations in two faint M31 dwarf satellites, Andromeda XI and Andromeda XIII. Using archival images from the Wide Field Planetary Camera 2 onboard the Hubble Space Telescope, we characterize the horizontal branch (HB) morphologies and the RR Lyrae (RRL) populations of these two faint dwarf satellites. Our new template light-curve fitting routine [Robust RR Lyrae light curve FITing (RRFIT)] has been used to detect and characterize RRL populations in both galaxies. The mean periods of RRab (RR0) stars in And XI and And XIII are = 0.621 ± 0.026 (error1) ± 0.022 (error2) and 0.648 ± 0.026 (error1) ± 0.022 (error2), respectively, where 'error1' represents the standard error of the mean, while 'error2' is based on our synthetic light-curve simulations. The RRL populations in these galaxies show a lack of RRab stars with high amplitudes [Amp (V) > 1.0 mag] and relatively short periods (? d), yet their period-V-band amplitude [P- Amp (V)] relations track the relation defined by the M31 field halo RRL populations at ˜11 kpc from the centre of M31. The metallicities of the RRab stars are calculated via a relationship between [Fe/H], log Pab and Amp(V). The resultant abundances ([ Fe/H ]And XI=-1.75; [ Fe/H ]And XIII=-1.74) are consistent with the values calculated from the red giant branch slope, indicating that our measurements are not significantly affected by RRL evolutionary away from the zero-age HB. The distance to each galaxy, based on the absolute V magnitudes of the RRab stars, is (m-M)0, V= 24.33 ± 0.05 for And XI and (m-M)0, V= 24.62 ± 0.05 for And XIII. We discuss the origins of And XI and And XIII based on a comparative analysis of the luminosity-metallicity relation of Local Group dwarf galaxies. Based on observations taken with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute.

  6. VizieR Online Data Catalog: VI light curves of SMC RR Lyrae (Soszynski+, 2010)

    NASA Astrophysics Data System (ADS)

    Soszynski, I.; Udalski, A.; Szymanski, M. K.; Kubiak, M.; Pietrzynski, G.; Wyrzykowski, L.; Ulaczyk, K.; Poleski, R.

    2010-11-01

    The ninth part of the OGLE-III Catalog of Variable Stars (OIII-CVS) comprises RR Lyr stars in the Small Magellanic Cloud (SMC). Our sample consists of 2475 variable stars, of which 1933 pulsate in the fundamental mode (RRab), 175 are the first overtone pulsators (RRc), 258 oscillate simultaneously in both modes (RRd) and 109 stars are suspected second-overtone pulsators (RRe). 30 objects are Galactic RR Lyr stars seen in the foreground of the SMC. (6 data files).

  7. RR Lyrae Luminosity Differences between Oosterhoff Group I and II Cluster Systems and the Origin of the Oosterhoff Dichotomy

    NASA Astrophysics Data System (ADS)

    Lee, Jae-Woo; Carney, Bruce W.

    1999-09-01

    We present a comparative study of the Oosterhoff II cluster M2 and the Oosterhoff I cluster M3. Both have similar metallicities, [Fe/H]=-1.62 for M2 and -1.66 for M3, but very different horizontal-branch (HB) morphologies (B-R)/(B+V+R)=0.92 for M2 and 0.08 for M3. A period shift analysis and main-sequence fitting show that RRab variables in M2 are about 0.2 mag brighter than those in M3. Comparisons of the M2 period shift with Oosterhoff I clusters NGC 3201 and NGC 7006 also yield similar results, while a comparison between M2 and the Oosterhoff II cluster NGC 5986 reveals that the RR Lyrae luminosities are very similar. The luminosity difference is thought to be due to the evolutionary effect described in 1990 by Lee, Demarque, & Zinn: the M2 RRab variables have evolved away from the zero-age horizontal branch (ZAHB), while most M3 RRab variables lie near the ZAHB. A comparison of the mean period change rates of two clusters supports this hypothesis. Our relative age estimation using the difference in color between the base of giant branch and turn-off point shows that M2 is about 2 Gyr older than M3. Our result strongly suggests that the Oosterhoff dichotomy is due to age differences between Oosterhoff group I and II. This is consistent with the idea that the global second parameter is age. We discuss the kinematic differences between Oosterhoff group I and II clusters. Our result shows that the Oosterhoff group I clusters have zero or retrograde rotation with =-68+/-56 km s^-1 and sigma_los=131+/-28 km s^-1, while the Oosterhoff group II clusters have prograde rotation with =+94+/-47 km s^-1 and sigma_los=115+/-29 km s^-1, confirming a similar conclusion of van den Bergh. The difference in kinematics and ages between Oosterhoff group I and II clusters suggests that they may have different origins: The Oosterhoff II clusters were formed very early in the proto-Galaxy while the Oosterhoff I clusters were formed at different locations and at a later

  8. Finding, Characterizing, and Classifying Variable Sources in Multi-epoch Sky Surveys: QSOs and RR Lyrae in PS1 3π data

    NASA Astrophysics Data System (ADS)

    Hernitschek, Nina; Schlafly, Edward F.; Sesar, Branimir; Rix, Hans-Walter; Hogg, David W.; Ivezić, Željko; Grebel, Eva K.; Bell, Eric F.; Martin, Nicolas F.; Burgett, W. S.; Flewelling, H.; Hodapp, K. W.; Kaiser, N.; Magnier, E. A.; Metcalfe, N.; Wainscoat, R. J.; Waters, C.

    2016-01-01

    In area and depth, the Pan-STARRS1 (PS1) 3π survey is unique among many-epoch, multi-band surveys and has enormous potential for the all-sky identification of variable sources. PS1 has observed the sky typically seven times in each of its five bands (grizy) over 3.5 years, but unlike SDSS, not simultaneously across the bands. Here we develop a new approach for quantifying statistical properties of non-simultaneous, sparse, multi-color light curves through light curve structure functions, effectively turning PS1 into a ∼35-epoch survey. We use this approach to estimate variability amplitudes and timescales (ωr, τ) for all point sources brighter than rP1 = 21.5 mag in the survey. With PS1 data on SDSS Stripe 82 as “ground truth,” we use a Random Forest Classifier to identify QSOs and RR Lyrae based on their variability and their mean PS1 and WISE colors. We find that, aside from the Galactic plane, QSO and RR Lyrae samples of purity ∼75% and completeness ∼92% can be selected. On this basis we have identified a sample of ∼1,000,000 QSO candidates, as well as an unprecedentedly large and deep sample of ∼150,000 RR Lyrae candidates with distances from ∼10 to ∼120 kpc. Within the Draco dwarf spheroidal, we demonstrate a distance precision of 6% for RR Lyrae candidates. We provide a catalog of all likely variable point sources and likely QSOs in PS1, a total of 25.8 × 106 sources.

  9. Pulsation models for the 0.26 M⊙ star mimicking RR Lyrae pulsator. Model survey for the new class of variable stars

    NASA Astrophysics Data System (ADS)

    Smolec, R.; Pietrzyński, G.; Graczyk, D.; Pilecki, B.; Gieren, W.; Thompson, I.; Stępień, K.; Karczmarek, P.; Konorski, P.; Górski, M.; Suchomska, K.; Bono, G.; Prada, P. G. Moroni; Nardetto, N.

    2013-02-01

    We present non-linear hydrodynamic pulsation models for OGLE-BLG-RRLYR-02792 - a 0.26 M⊙ pulsator, component of the eclipsing binary system, analysed recently by Pietrzyński et al. The star's light and radial velocity curves mimic that of classical RR Lyrae stars, except for the bump in the middle of the ascending branch of the radial velocity curve. We show that the bump is caused by the 2:1 resonance between the fundamental mode and the second overtone - the same mechanism that causes the Hertzsprung bump progression in classical Cepheids. The models allow us to constrain the parameters of the star, in particular to estimate its absolute luminosity (≈33 L⊙) and effective temperature (≈6970 K, close to the blue edge of the instability strip). We conduct a model survey for the new class of low-mass pulsators similar to OGLE-BLG-RRLYR-02792 - products of evolution in the binary systems. We compute a grid of models with masses corresponding to half (or less) of the typical mass of RR Lyrae variable, 0.20 ≤ M ≤ 0.30 M⊙, and discuss the properties of the resulting light and radial velocity curves. Resonant bump progression is clear and may be used to distinguish such stars from classical RR Lyrae stars. We present the Fourier decomposition parameters for the modelled light and radial velocity curves. The expected values of the ϕ31 Fourier phase for the light curves differ significantly from that observed in RR Lyrae stars, which is another discriminant of the new class.

  10. Observations of RR Lyrae and X ARIETIS with the IUE satellite

    NASA Astrophysics Data System (ADS)

    Bonnell, J. T.; Bell, R. A.

    1984-12-01

    Seven low dispersion spectra of RR Lyr and 11 of X Ari were obtained with the long wave redundant camera of IUE. The RR Lyr was also observed in the low-dispersion mode with the SWP camera and in the high-dispersion mode with the LWR camera. The observed fluxes were compared with fluxes calculated by using synthetic spectra and angular diameters determined from photometry at longer wavelengths. The observed fluxes for RR Lyr were found to be significantly fainter than the computed ones. The RR Lyr was also found to be 0.4 magnitudes fainter at 2200A and 2500A during minimum light than it was during previous ultraviolet observations with the ANS satellite. It is suggested that both these differences are due to the star's secondary cycle (the Blazhko effect). One of the high-dispersion exposures made near maximum light was deep enough to reveal the cores of the Mg II h and k lines. No emission was observed and a strong interstellar absorption component was present. Emission features were generally absent from the SWP spectra. An agreement between observed and calculated fluxes was found for X Ari for which no Blazhko effect is observed.

  11. Pushing the Limits, Episode 2: K2 Observations of Extragalactic RR Lyrae Stars in the Dwarf Galaxy Leo IV

    NASA Astrophysics Data System (ADS)

    Molnár, L.; Pál, A.; Plachy, E.; Ripepi, V.; Moretti, M. I.; Szabó, R.; Kiss, L. L.

    2015-10-01

    We present the first observations of extragalactic pulsating stars in the K2 ecliptic survey of the Kepler space telescope. The variability of all three RR Lyrae stars in the dwarf spheroidal galaxy Leo IV was successfully detected, at a brightness of Kp ≈ 21.5 mag, from data collected during Campaign 1. We identified one modulated star and another likely Blazhko candidate with periods of 29.8 ± 0.9 days and more than 80 days, respectively. EPIC 210282473 represents the first star beyond the Magellanic Clouds for which the Blazhko period and cycle-to-cycle variations in the modulation were unambiguously measured. The photometric [Fe/H] indices of the stars agree with earlier results that Leo IV is a very metal-poor galaxy. Two out of the three stars blend with brighter background galaxies in the K2 frames. We demonstrate that image subtraction can be reliably used to extract photometry from faint confused sources, which will be crucial not only for the K2 mission but also for future space photometric missions.

  12. The Araucaria Project: The Distance to the Carina Dwarf Galaxy from Infrared Photometry of RR Lyrae Stars

    NASA Astrophysics Data System (ADS)

    Karczmarek, Paulina; Pietr´ski, Grzegorz; Gieren, Wolfgang; Suchomska, Ksenia; Konorski, Piotr; Górski, Marek; Pilecki, Bogumił; Graczyk, Dariusz; Wielgórski, Piotr

    2015-09-01

    We obtained single-phase near-infrared (NIR) magnitudes in the J- and K-band for a sample of 33 RR Lyrae (RRL) stars in the Carina dSph galaxy. Applying different theoretical and empirical calibrations of the NIR period-luminosity-metallicity relation for RRL stars, we find consistent results and obtain a true, reddening-corrected distance modulus of 20.118 ± 0.017 (statistical) ± 0.11 (systematic) mag. This value is in excellent agreement with the results obtained in the context of the Araucaria Project from NIR photometry of red clump stars (20.165 ± 0.015) and the tip of red giant branch (20.09 ± 0.03 ± 0.12 mag in the J band, 20.14 ± 0.04 ± 0.14 mag in the K band), as well as with most independent distance determinations to this galaxy. The NIR RRL method proved to be a reliable tool for accurate distance determination at the 5% level or better, particularly for galaxies and globular clusters that lack young standard candles, like Cepheids. Based on data collected with the VLT/HAWK-I instrument at ESO Paranal Observatory, Chile, as a part of a program 082.D-0123(B).

  13. The Araucaria Project: The Distance to the Carina Dwarf Galaxy from Infrared Photometry of RR Lyrae Stars

    NASA Astrophysics Data System (ADS)

    Karczmarek, Paulina; Pietrzyński, Grzegorz; Gieren, Wolfgang; Suchomska, Ksenia; Konorski, Piotr; Górski, Marek; Pilecki, Bogumił; Graczyk, Dariusz; Wielgórski, Piotr

    2015-09-01

    We obtained single-phase near-infrared (NIR) magnitudes in the J- and K-band for a sample of 33 RR Lyrae (RRL) stars in the Carina dSph galaxy. Applying different theoretical and empirical calibrations of the NIR period–luminosity–metallicity relation for RRL stars, we find consistent results and obtain a true, reddening-corrected distance modulus of 20.118 ± 0.017 (statistical) ± 0.11 (systematic) mag. This value is in excellent agreement with the results obtained in the context of the Araucaria Project from NIR photometry of red clump stars (20.165 ± 0.015) and the tip of red giant branch (20.09 ± 0.03 ± 0.12 mag in the J band, 20.14 ± 0.04 ± 0.14 mag in the K band), as well as with most independent distance determinations to this galaxy. The NIR RRL method proved to be a reliable tool for accurate distance determination at the 5% level or better, particularly for galaxies and globular clusters that lack young standard candles, like Cepheids. Based on data collected with the VLT/HAWK-I instrument at ESO Paranal Observatory, Chile, as a part of a program 082.D-0123(B).

  14. The Baade-Wesselink method and the distances to RR Lyrae stars. II - The field star X ARIETIS

    NASA Astrophysics Data System (ADS)

    Jones, Rodney V.; Carney, Bruce W.; Latham, David W.; Kurucz, Robert L.

    1987-01-01

    VR and JHK photometry and radial velocities with typical accuracies of 1 km/sec for the metal-poor RR Lyrae field star X Arietis. These data, along with unpublished UVBY photometry, have been used to derive the distance to X Ari using two variations of the Baade-Wesselink method. The possibility of photospheric velocity gradients that might distort the value of the systemic velocity and cause a phase shift was examined, and it was found that no gradient exists in the part of the stellar atmosphere considered. The phasing problem previously noted for VY Ser by Carney and Latham (1984) also occurs for X Ari when optical photometry is used to compute the effective temperatures, but not when the V - K color index is used. Possible causes of these phase shifts are discussed, and it is concluded that X Ari has an aggregate average V magnitude of 0.73-1.03 mag on the basis of the V - K results.

  15. RR Lyrae stars in the SDSS Stripe 82 region: period-color and amplitude-color relations

    NASA Astrophysics Data System (ADS)

    Ngeow, C.-C.; Kanbur, S.; Bhardwaj, A.; Singh, H.

    2016-05-01

    Investigation of period-color (PC) and amplitude-color (AC) relations at the maximum and minimum light for RR Lyrae (RRL) stars can be used to probe the interaction of the hydrogen ionization front with photosphere at the atmosphere for this type of pulsating variables. For example, theoretical calculation indicated that such interaction would occur at the minimum light for RRL stars and caused a flat PC relation. In the past, the PC and AC relations have been investigated by using either the (V - R) or (V - I) colors. Here, we extend previous works to multi-bands by analyzing the RRL stars in SDSS (Sloan Digitized Sky Survey) Stripe 82 region, at which multi-epoch data are available for RRL stars located within the footprint of Stripe 82 region in ugriz bands. We present the PC and AC relations in four colors after correcting for extinction. We found that the structure of PC and AC relations for this sample of RRL stars is more complicated than a linear regression fit.

  16. VizieR Online Data Catalog: Double-mode RR Lyrae stars in LINEAR (Poleski+, 2014)

    NASA Astrophysics Data System (ADS)

    Poleski, R.

    2014-11-01

    The LINEAR survey operated between 1998 and 2009 using two 1m telescopes. Each of the mosaic cameras had a 2deg2 field of view with a 2.25" pixel scale. Observations were collected without a filter and sometimes in nonphotometric conditions. On average, 250 epochs were collected per field, and the number rises to 500 for targets close to the ecliptic plane. Such a dataset is suitable for a search for periodic variable stars. The catalog of such objects was presented by Palaversa et al. (2013AJ....146..101P, Cat. J/AJ/146/101). It includes more than 7000 stars, most of which are RR Lyr pulsators. There are 2923 RRab and 990 RRc stars. We performed the search for other radial modes in RR Lyr type stars. (2 data files).

  17. EPIC 201585823, a rare triple-mode RR Lyrae star discovered in K2 mission data

    NASA Astrophysics Data System (ADS)

    Kurtz, Donald W.; Bowman, Dominic M.; Ebo, Simon J.; Moskalik, Paweł; Handberg, Rasmus; Lund, Mikkel N.

    2016-01-01

    We have discovered a new, rare triple-mode RR Lyr star, EPIC 201585823, in the Kepler K2 mission Campaign 1 data. This star pulsates primarily in the fundamental and first-overtone radial modes, and, in addition, a third non-radial mode. The ratio of the period of the non-radial mode to that of the first-overtone radial mode, 0.616 285, is remarkably similar to that seen in 11 other triple-mode RR Lyr stars, and in 260 RRc stars observed in the Galactic bulge. This systematic character promises new constraints on RR Lyr star models. We detected subharmonics of the non-radial mode frequency, which are a signature of period doubling of this oscillation; we note that this phenomenon is ubiquitous in RRc and RRd stars observed from space, and from ground with sufficient precision. The non-radial mode and subharmonic frequencies are not constant in frequency or in amplitude. The amplitude spectrum of EPIC 201585823 is dominated by many combination frequencies among the three interacting pulsation mode frequencies. Inspection of the phase relationships of the combination frequencies in a phasor plot explains the `upward' shape of the light curve. We also found that raw data with custom masks encompassing all pixels with significant signal for the star, but without correction for pointing changes, is best for frequency analysis of this star, and, by implication, other RR Lyr stars observed by the K2 mission. We compare several pipeline reductions of the K2 mission data for this star.

  18. The Early Chemical Enrichment Histories of Two Sculptor Group Dwarf Galaxies as Revealed by RR Lyrae Variables

    NASA Astrophysics Data System (ADS)

    Yang, Soung-Chul; Wagner-Kaiser, Rachel; Sarajedini, Ata; Kim, Sang Chul; Kyeong, Jaemann

    2014-03-01

    We present the results of our analysis of the RR Lyrae (RRL) variable stars detected in two transition-type dwarf galaxies (dTrans), ESO294-G010 and ESO410-G005 in the Sculptor group, which is known to be one of the closest neighboring galaxy groups to our Local Group. Using deep archival images from the Advanced Camera for Surveys on board the Hubble Space Telescope, we have identified a sample of RRL candidates in both dTrans galaxies (219 RRab (RR0) and 13 RRc (RR1) variables in ESO294-G010; 225 RRab and 44 RRc stars in ESO410-G005). The metallicities of the individual RRab stars are calculated via the period-amplitude-[Fe/H] relation derived by Alcock et al. This yields mean metallicities of lang[Fe/H]rangESO294 = -1.77 ± 0.03 and lang[Fe/H]rangESO410 = -1.64 ± 0.03. The RRL metallicity distribution functions (MDFs) are investigated further via simple chemical evolution models; these reveal the relics of the early chemical enrichment processes for these two dTrans galaxies. In the case of both galaxies, the shapes of the RRL MDFs are well described by pre-enrichment models. This suggests two possible channels for the early chemical evolution for these Sculptor group dTrans galaxies: (1) the ancient stellar populations of our target dwarf galaxies might have formed from the star forming gas which was already enriched through "prompt initial enrichment" or an "initial nucleosynthetic spike" from the very first massive stars, or (2) this pre-enrichment state might have been achieved by the end products from more evolved systems of their nearest neighbor, NGC 55. We also study the environmental effects of the formation and evolution of our target dTrans galaxies by comparing their properties with those of 79 volume limited (D ⊙ < 2 Mpc) dwarf galaxy samples in terms of the luminosity-metallicity relation and the H I gas content. The presence of these RRL stars strongly supports the idea that although the Sculptor Group galaxies have a considerably different

  19. The early chemical enrichment histories of two Sculptor group dwarf galaxies as revealed by RR lyrae variables

    SciTech Connect

    Yang, Soung-Chul; Kim, Sang Chul; Kyeong, Jaemann; Wagner-Kaiser, Rachel; Sarajedini, Ata

    2014-03-20

    We present the results of our analysis of the RR Lyrae (RRL) variable stars detected in two transition-type dwarf galaxies (dTrans), ESO294-G010 and ESO410-G005 in the Sculptor group, which is known to be one of the closest neighboring galaxy groups to our Local Group. Using deep archival images from the Advanced Camera for Surveys on board the Hubble Space Telescope, we have identified a sample of RRL candidates in both dTrans galaxies (219 RRab (RR0) and 13 RRc (RR1) variables in ESO294-G010; 225 RRab and 44 RRc stars in ESO410-G005). The metallicities of the individual RRab stars are calculated via the period-amplitude-[Fe/H] relation derived by Alcock et al. This yields mean metallicities of ([Fe/H]){sub ESO294} = –1.77 ± 0.03 and ([Fe/H]){sub ESO410} = –1.64 ± 0.03. The RRL metallicity distribution functions (MDFs) are investigated further via simple chemical evolution models; these reveal the relics of the early chemical enrichment processes for these two dTrans galaxies. In the case of both galaxies, the shapes of the RRL MDFs are well described by pre-enrichment models. This suggests two possible channels for the early chemical evolution for these Sculptor group dTrans galaxies: (1) the ancient stellar populations of our target dwarf galaxies might have formed from the star forming gas which was already enriched through 'prompt initial enrichment' or an 'initial nucleosynthetic spike' from the very first massive stars, or (2) this pre-enrichment state might have been achieved by the end products from more evolved systems of their nearest neighbor, NGC 55. We also study the environmental effects of the formation and evolution of our target dTrans galaxies by comparing their properties with those of 79 volume limited (D {sub ☉} < 2 Mpc) dwarf galaxy samples in terms of the luminosity-metallicity relation and the H I gas content. The presence of these RRL stars strongly supports the idea that although the Sculptor Group galaxies have a considerably

  20. RR Lyrae stars - A theoretical study of Bailey type c variables

    NASA Technical Reports Server (NTRS)

    Hubickyj, Olenka; Stothers, Richard B.

    1986-01-01

    New theoretical models of stars pulsating in the first overtone have been constructed to simulate RR Lyr variables of Bailey type c. Despite the use of different opacities, these new models agree very well with earlier models built by Christy and Stellingwerf. Quantitative comparisons using empirical light curves and velocity curves of metal-poor type c variables confirm the validity of the models. Masses of 0.55-0.65 solar mass and luminosities of 40-50 solar luminosities derived here for the type c variables, are consistent with previous results obtained for type ab variables. A Christy echo of the kind normally associated with fundamental-mode pulsators was detected in the interior velocity structure of one first-overtone model that happens to have a large velocity amplitude.

  1. Atmospheric dynamics in RR Lyrae stars: a high-resolution spectroscopic survey

    NASA Astrophysics Data System (ADS)

    Chadid, M.; Preston, G. W.

    2013-09-01

    We present a first detailed atmospheric dynamics study of 11 RRab stars: six Blazhko stars - RR Lyr, AS Vir, BS Aps, CD Vel, UV Oct and V1645 Sgr, and five non-Blazhko stars - DT Hya, WY Ant, XZ Aps, Z Mic and RV Oct. 32 hundred high-resolution spectra of these RRab stars were collected, during their pulsation periods and the Blazhko cycles, with the du Pont 2.5-m telescope at the Las Campanas Observatory and the 1.5-m telescope at the Haute Provence Observatory. We derived the dynamical parameters: dynamical accelerations, radius variations, rise time, shock amplitudes, full width at half-maximum (FWHM) and their variation during the Blazhko modulation. We find that, rise time excepted, these dynamical parameters are anticorrelated with change in instantaneous pulsation period during the Blazhko cycle. We detected a new bulge phenomenon in the radial velocity curve of Blazhko and non-Blazhko stars of our sample and we discuss newly detected redshifted Hα emission and its evolution during declining light. A new bump in the light curve is also detected: the lump. We associate the bulge phenomenon, lump and the redshifted emission with a new post-maximum shock wave ShPM. The bulge phenomenon and lump vary from star to star and with phase during Blazhko cycles of individual stars. We suspect but cannot prove irregularity from cycle to cycle in the radial velocity and FWHM curves of non-Blazhko stars. Finally, we discuss the origin of the Blazhko effect, giving a new empirical side for further theoretical models.

  2. The MACHO Project Large Magellanic Cloud Variable Star Inventory. XIII. Fourier Parameters for the First Overtone RR Lyrae Variables and the LMC Distance

    SciTech Connect

    Alcock, C; Alves, D; Axelrod, T; Becker, A; Bennett, D; Clement, C; Cook, K; Drake, A; Freeman, K; Geha, M; Griest, K; Lehner, M; Marshall, S; Minniti, D; Muzzin, A; Nelson, C; Peterson, B; Popowski, P; Pratt, M; Quinn, P; Rodgers, A; Rowe, J; Sutherland, W; Vandehei, T; Welch, D

    2003-12-31

    Shapes of RR Lyrae light curves can be described in terms of Fourier coefficients which past research has linked with physical characteristics such as luminosity, mass and temperature. Fourier coefficients have been derived for the V and R light curves of 785 overtone RR Lyrae variables in 16 MACHO fields near the bar of the LMC. In general, the Fourier phase differences {phi}{sub 21}, {phi}{sub 31} and {phi}{sub 41} increase and the amplitude ratio R{sub 21} decreases with increasing period. The coefficients for both the V and R magnitudes follow these patterns, but the phase differences for the R curves are on average slightly greater, and their amplitudes are about 20% smaller, than the ones for the V curves. The {phi}{sub 31} and R{sub 21} coefficients have been compared with those of the first overtone RR Lyrae variables in the Galactic globular clusters NGC 6441, M107, M5, M3, M2, {omega} Centauri and M68. The results indicate that many of the LMC variables have properties similar to the ones in M2, M3, M5 and the Oosterhoff type I variables in {omega} Cen, but they are different from the Oosterhoff type II variables in {omega} Cen. Equations derived from hydrodynamic pulsation models have been used to calculate the luminosity and temperature for the 330 bona fide first-overtone variables. The results indicate that they have Log L in the range 1.6 to 1.8 L{sub {center_dot}} and log T{sub eff} between 3.85 and 3.87. Based on these temperatures, a mean color excess E(V-R) = 0.08 mag, equivalent to E(B-V) = 0.14 mag, has been estimated for these 330 stars. The 80 M5-like variables (selected according to their location in the {phi}{sub 31} - log P plot) are used to determine an LMC distance. After correcting for the effects of extinction and crowding, a mean apparent magnitude < V{sub 0} > = 18.99 {+-} 0.02 (statistical) {+-} 0.16 (systematic) has been estimated for these 80 stars. Combining this with a mean absolute magnitude M{sub V} = 0.56 {+-} 0.06 for M5

  3. Spectroscopic Identification and Metallicity Determination of RR Lyrae Variables in Sloan, with a New Metallicity Calibration Including High-Temperature Phase Regions

    NASA Astrophysics Data System (ADS)

    Spalding, Eckhart; Wilhelm, R. J.; De Lee, N. M.

    2014-01-01

    RR Lyrae stars provide important distance markers for tracing out the metallicity and physical extent of tidal streams and the galactic halo. Here we present a method for potentially identifying a few thousand RRL stars by comparing low-resolution, single-epoch spectra from the Sloan Digital Sky Survey (SDSS) DR9. This method is tested against the heavily-sampled ‘Stripe 82’ of SDSS. We have also begun developing a new metallicity calibration that fills in the high-temperature regions in RR Lyrae phases for phase regions other than (and including) minimum light. Our calibration extends metallicity determinations provided by previous methods which were calibrated at minimum light only, and also has the potential for detecting shorter-period RRc stars. Phase information was taken from the MacAdam Student Observatory at the University of Kentucky, and the Moore Observatory at the University of Louisville. Spectroscopy was recorded at the University of Texas’ McDonald Observatory. This spectroscopic data set builds on a metallicity standard that we discuss. Ultimately, this new calibration will allow the gleaning of more accurate metallicity information from spectroscopic data taken by surveys such as SDSS.

  4. Peculiar double-periodic pulsation in RR Lyrae stars of the OGLE collection - I. Long-period stars with dominant radial fundamental mode

    NASA Astrophysics Data System (ADS)

    Smolec, R.; Prudil, Z.; Skarka, M.; Bakowska, K.

    2016-09-01

    We present the discovery of a new, peculiar form of double-periodic pulsation in RR Lyrae stars. In four, long-period (P > 0.6 d) stars observed by the Optical Gravitational Lensing Experiment, and classified as fundamental mode pulsators (RRab), we detect additional, low-amplitude variability, with period shorter than fundamental mode period. The period ratios fall in a range similar to double-mode fundamental and first overtone RR Lyrae stars (RRd), with the exception of one star, in which the period ratio is significantly lower and nearly exactly equals 0.7. Although period ratios are fairly different for the four stars, the light-curve shapes corresponding to the dominant, fundamental mode are very similar. The peak-to-peak amplitudes and amplitude ratios (Fourier parameters R21 and R31) are among the highest observed in RRab stars of similar period, while Fourier phases (ϕ21 and ϕ31) are among the lowest observed in RRab stars. If the additional variability is interpreted as due to radial first overtone, then, the four stars are the most extreme RRd variables of the longest pulsation periods known. Indeed, the observed period ratios can be well modelled with high-metallicity pulsation models. However, at such long pulsation periods, first overtone is typically damped. Five other candidates, with weak signature of additional variability, sharing the same characteristics, were also detected and are briefly discussed.

  5. CoRoT light curves of Blazhko RR Lyrae stars. Evidence of a strong correlation between phase and amplitude modulations of CoRoT ID 0105288363

    NASA Astrophysics Data System (ADS)

    Chadid, M.; Perini, C.; Bono, G.; Auvergne, M.; Baglin, A.; Weiss, W. W.; Deboscher, J.

    2011-03-01

    Context. The CoRoT - Convection Rotation and planetary Transits - space mission provides a unique opportunity to monitor RR Lyrae stars with excellent time-sampling, unprecedented photometric precision, and a long time base of 150 days. Aims: The pulsation characteristics of RR Lyrae stars rely on robust physics, but we still lack a firm quantitative understanding of the physical mechanisms driving the Blazhko modulation and the long-term changes in their pulsation behavior. We use the high-precision space data of an unknown RR Lyrae star CoRoT ID 0105288363 observed during a second long run centered on the Galaxy - LRc02 -, to improve our understanding of the pulsation properties of RR Lyrae stars. Methods: The CoRoT data were corrected using a jump and trend filtering code. We applied different period-finding techniques including Period04, MuFrAn, PDM, and SigSpec. Amplitude and phase modulation were investigated using an analytical function method as well as traditional O-C diagrams. Results: For the first time, we detect significant cycle-to-cycle changes in the Blazhko modulation, which appear to be analogous to those predicted by Stothers - owing to the suppression of turbulent convection - to explain this phenomenon. We discuss the clear correlations between the phase and the amplitude of the bump, and the skewness and acuteness of the light curve during different Blazhko cycles. We find that these quantities are strongly anticorrelated with the fundamental pulsation period. This provides a strong support to the slow convective cycle model suggested by Stothers. We also detect a long-term modulation period in the maximum brightness spectrum. A more extended coverage of the long-term modulation is required to constrain its period. Seventh-order side peaks of the pulsation multiplet structure are also visible with the left-side peak amplitudes being higher than those of the right. This has never previously been detected. Future theoretical investigations are

  6. An optimized method to identify RR Lyrae stars in the SDSS×Pan-STARRS1 overlapping area using a bayesian generative technique

    SciTech Connect

    Abbas, Mohamad; Grebel, Eva K.; Martin, N. F.; Kaiser, N.; Burgett, W. S.; Huber, M. E.; Waters, C.

    2014-07-01

    We present a method for selecting RR Lyrae (RRL) stars (or other types of variable stars) in the absence of a large number of multi-epoch data and light curve analyses. Our method uses color and variability selection cuts that are defined by applying a Gaussian Mixture Bayesian Generative Method (GMM) on 636 pre-identified RRL stars instead of applying the commonly used rectangular cuts. Specifically, our method selects 8115 RRL candidates (heliocentric distances < 70 kpc) using GMM color cuts from the Sloan Digital Sky Survey (SDSS) and GMM variability cuts from the Panoramic Survey Telescope and Rapid Response System 1 3π survey (PS1). Comparing our method with the Stripe 82 catalog of RRL stars shows that the efficiency and completeness levels of our method are ∼77% and ∼52%, respectively. Most contaminants are either non-variable main-sequence stars or stars in eclipsing systems. The method described here efficiently recovers known stellar halo substructures. It is expected that the current completeness and efficiency levels will further improve with the additional PS1 epochs (∼3 epochs per filter) that will be observed before the conclusion of the survey. A comparison between our efficiency and completeness levels using the GMM method to the efficiency and completeness levels using rectangular cuts that are commonly used yielded a significant increase in the efficiency level from ∼13% to ∼77% and an insignificant change in the completeness levels. Hence, we favor using the GMM technique in future studies. Although we develop it over the SDSS×PS1 footprint, the technique presented here would work well on any multi-band, multi-epoch survey for which the number of epochs is limited.

  7. Constraints on the Distance Moduli, Helium and Metal Abundances, and Ages of Globular Clusters from their RR Lyrae and Non-variable Horizontal-branch Stars. I. M3, M15, and M92

    NASA Astrophysics Data System (ADS)

    VandenBerg, Don A.; Denissenkov, P. A.; Catelan, Márcio

    2016-08-01

    Up-to-date isochrones, zero-age horizontal-branch (ZAHB) loci, and evolutionary tracks for core He-burning stars are applied to the color–magnitude diagrams of M3, M15, and M92, focusing in particular on their RR Lyrae populations. Periods for the ab- and c-type variables are calculated using the latest theoretical calibrations of {log} {P}{ab} and {log} {P}c as a function of luminosity, mass, effective temperature ({T}{{eff}}), and metallicity. Our models are generally able to reproduce the measured periods to well within the uncertainties implied by the stellar properties on which pulsation periods depend, as well as the mean periods and cluster-to-cluster differences in < {P}{ab}> and < {P}c> , on the assumption of well-supported values of E(B-V), {(m-M)}V, and [Fe/H]. While many of RR Lyrae in M3 lie close to the same ZAHB that fits the faintest horizontal-branch (HB) stars at bluer or redder colors, the M92 variables are all significantly evolved stars from ZAHB locations on the blue side of the instability strip. M15 appears to contain a similar population of HB stars as M92, along with additional helium-enhanced populations not present in the latter which comprise most of its RR Lyrae stars. The large number of variables in M15 and the similarity of the observed values of < {P}{ab}> and < {P}c> in M15 and M92 can be explained by HB models that allow for variations in Y. Similar ages (∼12.5 Gyr) are found for all three clusters, making them significantly younger than the field halo subgiant HD 140283. Our analysis suggests a preference for stellar models that take diffusive processes into account.

  8. Constraints on the Distance Moduli, Helium and Metal Abundances, and Ages of Globular Clusters from their RR Lyrae and Non-variable Horizontal-branch Stars. I. M3, M15, and M92

    NASA Astrophysics Data System (ADS)

    VandenBerg, Don A.; Denissenkov, P. A.; Catelan, Márcio

    2016-08-01

    Up-to-date isochrones, zero-age horizontal-branch (ZAHB) loci, and evolutionary tracks for core He-burning stars are applied to the color–magnitude diagrams of M3, M15, and M92, focusing in particular on their RR Lyrae populations. Periods for the ab- and c-type variables are calculated using the latest theoretical calibrations of {log} {P}{ab} and {log} {P}c as a function of luminosity, mass, effective temperature ({T}{{eff}}), and metallicity. Our models are generally able to reproduce the measured periods to well within the uncertainties implied by the stellar properties on which pulsation periods depend, as well as the mean periods and cluster-to-cluster differences in < {P}{ab}> and < {P}c> , on the assumption of well-supported values of E(B-V), {(m-M)}V, and [Fe/H]. While many of RR Lyrae in M3 lie close to the same ZAHB that fits the faintest horizontal-branch (HB) stars at bluer or redder colors, the M92 variables are all significantly evolved stars from ZAHB locations on the blue side of the instability strip. M15 appears to contain a similar population of HB stars as M92, along with additional helium-enhanced populations not present in the latter which comprise most of its RR Lyrae stars. The large number of variables in M15 and the similarity of the observed values of < {P}{ab}> and < {P}c> in M15 and M92 can be explained by HB models that allow for variations in Y. Similar ages (˜12.5 Gyr) are found for all three clusters, making them significantly younger than the field halo subgiant HD 140283. Our analysis suggests a preference for stellar models that take diffusive processes into account.

  9. The Optical Gravitational Lensing Experiment. The OGLE-III Catalog of Variable Stars. XI. RR Lyrae Stars in the Galactic Bulge

    NASA Astrophysics Data System (ADS)

    Soszyński, I.; Dziembowski, W. A.; Udalski, A.; Poleski, R.; Szymański, M. K.; Kubiak, M.; Pietrzyński, G.; Wyrzykowski, Ł.; Ulaczyk, K.; Kozłowski, S.; Pietrukowicz, P.

    2011-03-01

    The eleventh part of the OGLE-III Catalog of Variable Stars (OIII-CVS) contains 16 836 RR Lyr stars detected in the OGLE fields toward the Galactic bulge. The total sample is composed of 11 756 RR Lyr stars pulsating in the fundamental mode (RRab), 4989 overtone pulsators (RRc), and 91 double-mode (RRd) stars. About 400 RR Lyr stars are members of the Sagittarius Dwarf Spheroidal Galaxy. The catalog includes the time-series photometry collected in the course of the OGLE survey, basic parameters of the stars, finding charts, and cross-identifications with other catalogs of RR Lyr stars toward the Milky Way center. We notice that some RRd stars in the Galactic bulge show unusually short periods and small ratio of periods, down to PF≍0.35 days and P1O/PF≍0.726. In the Petersen diagram double-mode RRLyr stars form a parabola-like structure, which connects shorter- and longer-period RRd stars. We show that the unique properties of the bulge RRd stars may be explained by allowing for the wide range of the metal abundance extending up to [Fe/H]≍-0.36. We report the discovery of an RR Lyr star with additional eclipsing variability with the orbital period of 15.2447 days. Some statistical features of the RRLyr sample are presented. We discuss potential applications of our catalog in studying the structure and history of the central region of the Galaxy, mapping the interstellar extinction toward the bulge, studying globular clusters and the Sagittarius Dwarf Galaxy.

  10. ON THE DISTANCE OF THE GLOBULAR CLUSTER M4 (NGC 6121) USING RR LYRAE STARS. I. OPTICAL AND NEAR-INFRARED PERIOD-LUMINOSITY AND PERIOD-WESENHEIT RELATIONS

    SciTech Connect

    Braga, V. F.; Bono, G.; Buonanno, R.; Dall'Ora, M.; Coppola, G.; Marconi, M.; Stetson, P. B.; Ferraro, I.; Iannicola, G.; Marengo, M.; Neeley, J.; Persson, S. E.; Freedman, W.; Madore, B. F.; Monson, A.; Rich, J.; Scowcroft, V.; Seibert, M.; Matsunaga, N.

    2015-02-01

    We present new distance determinations to the nearby globular M4 (NGC 6121) based on accurate optical and near-infrared (NIR) mean magnitudes for fundamental (FU) and first overtone (FO) RR Lyrae variables (RRLs), and new empirical optical and NIR period-luminosity (PL) and period-Wesenheit (PW) relations. We have found that optical-NIR and NIR PL and PW relations are affected by smaller standard deviations than optical relations. The difference is the consequence of a steady decrease in the intrinsic spread of cluster RRL apparent magnitudes at fixed period as longer wavelengths are considered. The weighted mean visual apparent magnitude of 44 cluster RRLs is =13.329 ± 0.001 (standard error of the mean) ±0.177 (weighted standard deviation) mag. Distances were estimated using RR Lyr itself to fix the zero-point of the empirical PL and PW relations. Using the entire sample (FU+FO) we found weighted mean true distance moduli of 11.35 ± 0.03 ± 0.05 mag and 11.32 ± 0.02 ± 0.07 mag. Distances were also evaluated using predicted metallicity dependent PLZ and PWZ relations. We found weighted mean true distance moduli of 11.283 ± 0.010 ± 0.018 mag (NIR PLZ) and 11.272 ± 0.005 ± 0.019 mag (optical-NIR and NIR PWZ). The above weighted mean true distance moduli agree within 1σ. The same result is found from distances based on PWZ relations in which the color index is independent of the adopted magnitude (11.272 ± 0.004 ± 0.013 mag). These distances agree quite well with the geometric distance provided by Kaluzny et al. based on three eclipsing binaries. The available evidence indicates that this approach can provide distances to globulars hosting RRLs with a precision better than 2%-3%.

  11. On the Distance of the Globular Cluster M4 (NGC 6121) Using RR Lyrae Stars. I. Optical and Near-infrared Period-Luminosity and Period-Wesenheit Relations

    NASA Astrophysics Data System (ADS)

    Braga, V. F.; Dall'Ora, M.; Bono, G.; Stetson, P. B.; Ferraro, I.; Iannicola, G.; Marengo, M.; Neeley, J.; Persson, S. E.; Buonanno, R.; Coppola, G.; Freedman, W.; Madore, B. F.; Marconi, M.; Matsunaga, N.; Monson, A.; Rich, J.; Scowcroft, V.; Seibert, M.

    2015-02-01

    We present new distance determinations to the nearby globular M4 (NGC 6121) based on accurate optical and near-infrared (NIR) mean magnitudes for fundamental (FU) and first overtone (FO) RR Lyrae variables (RRLs), and new empirical optical and NIR period-luminosity (PL) and period-Wesenheit (PW) relations. We have found that optical-NIR and NIR PL and PW relations are affected by smaller standard deviations than optical relations. The difference is the consequence of a steady decrease in the intrinsic spread of cluster RRL apparent magnitudes at fixed period as longer wavelengths are considered. The weighted mean visual apparent magnitude of 44 cluster RRLs is =13.329 ± 0.001 (standard error of the mean) ±0.177 (weighted standard deviation) mag. Distances were estimated using RR Lyr itself to fix the zero-point of the empirical PL and PW relations. Using the entire sample (FU+FO) we found weighted mean true distance moduli of 11.35 ± 0.03 ± 0.05 mag and 11.32 ± 0.02 ± 0.07 mag. Distances were also evaluated using predicted metallicity dependent PLZ and PWZ relations. We found weighted mean true distance moduli of 11.283 ± 0.010 ± 0.018 mag (NIR PLZ) and 11.272 ± 0.005 ± 0.019 mag (optical-NIR and NIR PWZ). The above weighted mean true distance moduli agree within 1σ. The same result is found from distances based on PWZ relations in which the color index is independent of the adopted magnitude (11.272 ± 0.004 ± 0.013 mag). These distances agree quite well with the geometric distance provided by Kaluzny et al. based on three eclipsing binaries. The available evidence indicates that this approach can provide distances to globulars hosting RRLs with a precision better than 2%-3%.

  12. VVV SURVEY NEAR-INFRARED PHOTOMETRY OF KNOWN BULGE RR LYRAE STARS: THE DISTANCE TO THE GALACTIC CENTER AND ABSENCE OF A BARRED DISTRIBUTION OF THE METAL-POOR POPULATION

    SciTech Connect

    Dékány, I.; Minniti, D.; Catelan, M.; Zoccali, M.; Hempel, M.; Saito, R. K.

    2013-10-20

    We have combined optical and near-infrared data of known RR Lyrae (RRL) stars in the bulge in order to study the spatial distribution of its metal-poor component by measuring precise reddening values and distances of 7663 fundamental-mode RRL stars with high-quality photometry. We obtain a distance to the Galactic center of R {sub 0} = 8.33 ± 0.05 ± 0.14 kpc. We find that the spatial distribution of the RRL stars differs from the structures traced by the predominantly metal-rich red clump (RC) stars. Unlike the RC stars, the RRL stars do not trace a strong bar, but have a more spheroidal, centrally concentrated distribution, showing only a slight elongation in its very center. We find a hint of bimodality in the density distribution at high southern latitudes (b < –5°), which needs to be confirmed by extending the areal coverage of the current census. The different spatial distributions of the metal-rich and metal-poor stellar populations suggest that the Milky Way has a composite bulge.

  13. AMPLITUDE FINE STRUCTURE IN THE CEPHEID P-L RELATION. I. AMPLITUDE DISTRIBUTION ACROSS THE RR LYRAE INSTABILITY STRIP MAPPED USING THE ACCESSIBILITY RESTRICTION IMPOSED BY THE HORIZONTAL BRANCH

    SciTech Connect

    Sandage, Allan

    2010-10-10

    The largest amplitude light curves for both RR Lyrae (RRL) variables and classical Cepheids with periods less than 10 days and greater than 20 days occur at the blue edge of the respective instability strips. It is shown that the equation for the decrease in amplitude with penetration into the strip from the blue edge, and hence the amplitude fine structure within the strip, is the same for RRL and the Cepheids despite their metallicity differences. However, the manifestation of this identity is different between the two classes of variables because the sampling of the RRL strip is restricted by the discrete strip positions of the horizontal branch, a restriction that is absent for the Cepheids in stellar aggregates with a variety of ages. To show the similarity of the strip amplitude fine structure for RRL and Cepheids, we make a grid of lines of constant amplitude in the H-R diagram of the strip using amplitude data for classical Cepheids in the Galaxy, LMC, and SMC. The model implicit in the grid, that also contains lines of constant period, is used to predict the correlations between period, amplitude, and color for the two Oosterhoff RRL groups in globular clusters. The good agreement of the predictions with the observations using the classical Cepheid amplitude fine structure also for the RRL shows one aspect of the unity of the pulsation processes between the two classes of variables.

  14. Nonlinear beat Cepheid and RR Lyrae models

    NASA Astrophysics Data System (ADS)

    Kolláth, Z.; Buchler, J. R.; Szabó, R.; Csubry, Z.

    2002-04-01

    The numerical hydrodynamic modelling of beat Cepheid behavior has been a long-standing quest in which purely radiative models have failed consistently. We find that beat pulsations occur quite naturally when turbulent convection is accounted for in our hydrodynamics code. The developments of a relaxation code and of a Floquet stability analysis greatly facilitate the search for and the analysis of beat Cepheid models. The conditions for the occurrence of beat behavior can be understood easily and at a fundamental level with the help of amplitude equations.

  15. Variables en la región central del cúmulo globular NGC 3201: descomposición de Fourier de las curvas de luz de las RR Lyrae y análisis de la relación período-luminosidad de las SX Phoenicis

    NASA Astrophysics Data System (ADS)

    Ahumada, J. A.; Arellano Ferro, A.; Calderón, J. H.; Kains, N.

    2015-08-01

    We present CCD time-series observations of the central region of the globular cluster NGC 3201, collected from CASLEO in March 2013, with the aim of performing the Fourier decomposition of the light curves of the RR Lyrae variables. This procedure, applied to the RRab-type stars, gave a mean value [Fe/H], for the cluster metallicity, and 5.00 0.22 kpc, for the cluster distance. The values found from two RRc stars are consistent with those derived previously. Because of differential reddening across the cluster field, individual reddenings for the RRab stars were estimated from their curves, resulting in an average value . An investigation of the light curves of stars in the blue straggler region led to the discovery of three new SX Phoenicis variables. The period-luminosity relation of the SX Phoenicis was used for an independent determination of the distance to the cluster and of the individual reddenings of these variables.

  16. RR Lyrae stars in the Andromeda satellite galaxies

    NASA Astrophysics Data System (ADS)

    Cusano, F.; Garofalo, A.; Clementini, G.

    2016-05-01

    In this contribution we summarize results on the search for variable stars and the study of the resolved stellar populations in four dwarf spheroidal satellites of the Andromeda galaxy that we have observed with the Large Binocular Cameras (LBC) at the Large Binocular Telescope (LBT).

  17. Pseudosymmetric features of non-centrosymmetric AB type crystals

    NASA Astrophysics Data System (ADS)

    Gazhulina, A. P.; Marychev, M. O.

    2016-07-01

    This work is supplement to our previous investigation (Gazhulina and Marychev, 2015) [1]. We have considered pseudosymmetric features with respect to the operation of inversion (pseudoinversion) for 340 non-centrosymmetric AB type crystals. Analysis of the features of particular structure types allowed us to determine the positions of pseudoinversion centers, subdivide them into separate types, and classify the entire set of crystals studied with respect to the types of pseudoinversion centers and peculiarities of the behavior of the degree of pseudoinversion depending on the ratio of atomic numbers of A and B components. For each group of crystals, average values and lower boundaries of the maximum pseudoinversion are determined and distribution with respect to the degree of pseudoinversion is constructed.

  18. LYRA Mid-Term Periodicities

    NASA Astrophysics Data System (ADS)

    Wauters, L.; Dominique, M.; Dammasch, I. E.

    2016-08-01

    The spectra of the PROBA2/LYRA data, similarly to every other solar time series, show predominant periodicities that can be of solar or instrumental origin. In this article, we compare the main periodicities characterizing the LYRA spectrum to those found in the sunspot number, in the 10.7 cm flux, in an X-ray flare index, and in the sunspot area evolution. We focused on the 2010 to 2014 time range, for which the LYRA data are available, although we also briefly address the evolution of the main periodicities in the longer range. The mid-term periodicities at {˜} 28, {˜} 44, {˜} 54, {˜} 59, {˜} 100, {˜} 110, and {˜} 150 days appear as highly significant in several analyzed datasets. The consistency of distinct periodicities between datasets provides characteristics for the global Sun. This consistency also strengthens the reliability of LYRA data.

  19. PULSATION PERIOD VARIATIONS IN THE RRc LYRAE STAR KIC 5520878

    SciTech Connect

    Hippke, Michael; Learned, John G.; Zee, A.; Edmondson, William H.; Lindner, John F.; Kia, Behnam; Ditto, William L.; Stevens, Ian R. E-mail: jgl@phys.hawaii.edu E-mail: w.h.edmondson@bham.ac.uk E-mail: wditto@hawaii.edu E-mail: irs@star.sr.bham.ac.uk

    2015-01-01

    Learned et al. proposed that a sufficiently advanced extra-terrestrial civilization may tickle Cepheid and RR Lyrae variable stars with a neutrino beam at the right time, thus causing them to trigger early and jogging the otherwise very regular phase of their expansion and contraction. This would turn these stars into beacons to transmit information throughout the galaxy and beyond. The idea is to search for signs of phase modulation (in the regime of short pulse duration) and patterns, which could be indicative of intentional, omnidirectional signaling. We have performed such a search among variable stars using photometric data from the Kepler space telescope. In the RRc Lyrae star KIC 5520878, we have found two such regimes of long and short pulse durations. The sequence of period lengths, expressed as time series data, is strongly autocorrelated, with correlation coefficients of prime numbers being significantly higher (p = 99.8%). Our analysis of this candidate star shows that the prime number oddity originates from two simultaneous pulsation periods and is likely of natural origin. Simple physical models elucidate the frequency content and asymmetries of the KIC 5520878 light curve. Despite this SETI null result, we encourage testing of other archival and future time-series photometry for signs of modulated stars. This can be done as a by-product to the standard analysis, and can even be partly automated.

  20. Pulsation Period Variations in the RRc Lyrae Star KIC 5520878

    NASA Astrophysics Data System (ADS)

    Hippke, Michael; Learned, John G.; Zee, A.; Edmondson, William H.; Lindner, John F.; Kia, Behnam; Ditto, William L.; Stevens, Ian R.

    2015-01-01

    Learned et al. proposed that a sufficiently advanced extra-terrestrial civilization may tickle Cepheid and RR Lyrae variable stars with a neutrino beam at the right time, thus causing them to trigger early and jogging the otherwise very regular phase of their expansion and contraction. This would turn these stars into beacons to transmit information throughout the galaxy and beyond. The idea is to search for signs of phase modulation (in the regime of short pulse duration) and patterns, which could be indicative of intentional, omnidirectional signaling. We have performed such a search among variable stars using photometric data from the Kepler space telescope. In the RRc Lyrae star KIC 5520878, we have found two such regimes of long and short pulse durations. The sequence of period lengths, expressed as time series data, is strongly autocorrelated, with correlation coefficients of prime numbers being significantly higher (p = 99.8%). Our analysis of this candidate star shows that the prime number oddity originates from two simultaneous pulsation periods and is likely of natural origin. Simple physical models elucidate the frequency content and asymmetries of the KIC 5520878 light curve. Despite this SETI null result, we encourage testing of other archival and future time-series photometry for signs of modulated stars. This can be done as a by-product to the standard analysis, and can even be partly automated.

  1. Multi-Filter Photometric Analysis of Three β Lyrae-type Eclipsing Binary Stars

    NASA Astrophysics Data System (ADS)

    Gardner, T.; Hahs, G.; Gokhale, V.

    2015-12-01

    We present light curve analysis of three variable stars, ASAS J105855+1722.2, NSVS 5066754, and NSVS 9091101. These objects are selected from a list of β- Lyrae candidates published by Hoffman et al. (2008). Light curves are generated using data collected at the the 31-inch NURO telescope at the Lowell Observatory in Flagstaff, Arizona in three filters: Bessell B, V, and R. Additional observations were made using the 14-inch Meade telescope at the Truman State Observatory in Kirksville, Missouri using Baader R, G, and B filters. In this paper, we present the light curves for these three objects and generate a truncated eight-term Fourier fit to these light curves. We use the Fourier coefficients from this fit to confirm ASAS J105855+1722.2 and NSVS 5066754 as β Lyrae type systems, and NSVS 9091101 to possibly be a RR Lyrae-type system. We measure the O'Connell effect observed in two of these systems (ASAS J105855+1722.2 and NSVS 5066754), and quantify this effect by calculating the "Light Curve Asymmetry" (LCA) and the "O'Connell Effect Ratio" (OER).

  2. Classification of octet AB-type binary compounds using dynamical charges: A materials informatics perspective

    SciTech Connect

    Pilania, G.; Gubernatis, J. E.; Lookman, T.

    2015-12-03

    The role of dynamical (or Born effective) charges in classification of octet AB-type binary compounds between four-fold (zincblende/wurtzite crystal structures) and six-fold (rocksalt crystal structure) coordinated systems is discussed. We show that the difference in the dynamical charges of the fourfold and sixfold coordinated structures, in combination with Harrison’s polarity, serves as an excellent feature to classify the coordination of 82 sp–bonded binary octet compounds. We use a support vector machine classifier to estimate the average classification accuracy and the associated variance in our model where a decision boundary is learned in a supervised manner. Lastly, we compare the out-of-sample classification accuracy achieved by our feature pair with those reported previously.

  3. Classification of octet AB-type binary compounds using dynamical charges: A materials informatics perspective

    NASA Astrophysics Data System (ADS)

    Pilania, G.; Gubernatis, J. E.; Lookman, T.

    2015-12-01

    The role of dynamical (or Born effective) charges in classification of octet AB-type binary compounds between four-fold (zincblende/wurtzite crystal structures) and six-fold (rocksalt crystal structure) coordinated systems is discussed. We show that the difference in the dynamical charges of the fourfold and sixfold coordinated structures, in combination with Harrison’s polarity, serves as an excellent feature to classify the coordination of 82 sp-bonded binary octet compounds. We use a support vector machine classifier to estimate the average classification accuracy and the associated variance in our model where a decision boundary is learned in a supervised manner. Finally, we compare the out-of-sample classification accuracy achieved by our feature pair with those reported previously.

  4. Classification of octet AB-type binary compounds using dynamical charges: A materials informatics perspective

    DOE PAGESBeta

    Pilania, G.; Gubernatis, J. E.; Lookman, T.

    2015-12-03

    The role of dynamical (or Born effective) charges in classification of octet AB-type binary compounds between four-fold (zincblende/wurtzite crystal structures) and six-fold (rocksalt crystal structure) coordinated systems is discussed. We show that the difference in the dynamical charges of the fourfold and sixfold coordinated structures, in combination with Harrison’s polarity, serves as an excellent feature to classify the coordination of 82 sp–bonded binary octet compounds. We use a support vector machine classifier to estimate the average classification accuracy and the associated variance in our model where a decision boundary is learned in a supervised manner. Lastly, we compare the out-of-samplemore » classification accuracy achieved by our feature pair with those reported previously.« less

  5. Classification of octet AB-type binary compounds using dynamical charges: A materials informatics perspective

    PubMed Central

    Pilania, G.; Gubernatis, J. E.; Lookman, T.

    2015-01-01

    The role of dynamical (or Born effective) charges in classification of octet AB-type binary compounds between four-fold (zincblende/wurtzite crystal structures) and six-fold (rocksalt crystal structure) coordinated systems is discussed. We show that the difference in the dynamical charges of the fourfold and sixfold coordinated structures, in combination with Harrison’s polarity, serves as an excellent feature to classify the coordination of 82 sp–bonded binary octet compounds. We use a support vector machine classifier to estimate the average classification accuracy and the associated variance in our model where a decision boundary is learned in a supervised manner. Finally, we compare the out-of-sample classification accuracy achieved by our feature pair with those reported previously. PMID:26631979

  6. Phylogenetic and environmental diversity of DsrAB-type dissimilatory (bi)sulfite reductases

    PubMed Central

    Müller, Albert Leopold; Kjeldsen, Kasper Urup; Rattei, Thomas; Pester, Michael; Loy, Alexander

    2015-01-01

    The energy metabolism of essential microbial guilds in the biogeochemical sulfur cycle is based on a DsrAB-type dissimilatory (bi)sulfite reductase that either catalyzes the reduction of sulfite to sulfide during anaerobic respiration of sulfate, sulfite and organosulfonates, or acts in reverse during sulfur oxidation. Common use of dsrAB as a functional marker showed that dsrAB richness in many environments is dominated by novel sequence variants and collectively represents an extensive, largely uncharted sequence assemblage. Here, we established a comprehensive, manually curated dsrAB/DsrAB database and used it to categorize the known dsrAB diversity, reanalyze the evolutionary history of dsrAB and evaluate the coverage of published dsrAB-targeted primers. Based on a DsrAB consensus phylogeny, we introduce an operational classification system for environmental dsrAB sequences that integrates established taxonomic groups with operational taxonomic units (OTUs) at multiple phylogenetic levels, ranging from DsrAB enzyme families that reflect reductive or oxidative DsrAB types of bacterial or archaeal origin, superclusters, uncultured family-level lineages to species-level OTUs. Environmental dsrAB sequences constituted at least 13 stable family-level lineages without any cultivated representatives, suggesting that major taxa of sulfite/sulfate-reducing microorganisms have not yet been identified. Three of these uncultured lineages occur mainly in marine environments, while specific habitat preferences are not evident for members of the other 10 uncultured lineages. In summary, our publically available dsrAB/DsrAB database, the phylogenetic framework, the multilevel classification system and a set of recommended primers provide a necessary foundation for large-scale dsrAB ecology studies with next-generation sequencing methods. PMID:25343514

  7. Observations of RR Lyrae Stars in M15 With Small Telescopes

    NASA Astrophysics Data System (ADS)

    Stoltz, J. M.; West, M. L.

    2004-05-01

    Images of the globular cluster M15 were taken with a CCD using Meade 8 inch and 12 inch telescopes. Our intention was to reproduce the photographs by Duncan made at the 100 inch telescope in 1932 and published as a laboratory exercise by Gingerich in Sky and Telescope in 1967. Images were collected on eleven nights, but only three were clear enough for differential photometry. These were analyzed with AIP for Windows (Burnell) and yielded phased light curves which fit with Clement's values for period and epoch of maximum brightness for four of the six stars measured (Bailey's stars 4, 5, 8, 11, 14, 15). We plan to obtain more images of this cluster next winter and to investigate other clusters as well. We hope to improve our techniques for observing in cloudy and light polluted metropolitan New Jersey.

  8. VizieR Online Data Catalog: Chemical compositions of 11 RR Lyrae (For+, 2011)

    NASA Astrophysics Data System (ADS)

    For, B.-Q.; Sneden, C.; Preston, G. W.

    2012-01-01

    The spectroscopic data were obtained with the du Pont 2.5m telescope at the Las Campanas Observatory (LCO), using a cross-dispersed echelle spectrograph with a total wavelength coverage of 3500-9000Å. See Section 3 of For et al. 2011, Cat. J/ApJS/194/38, for details of data reduction. (4 data files).

  9. VizieR Online Data Catalog: RR Lyrae AllWise photometry (Klein+, 2014)

    NASA Astrophysics Data System (ADS)

    Klein, C. R.; Righards, J. W.; Butler, N. R.; Bloom, J. S.

    2015-01-01

    In this analysis, we make use of the most recent WISE data release, AllWISE. The AllWISE Data Release (made public 2013 November 13, Cat. II/328) combines the 4-Band Cryogenic Survey (main WISE mission covering the full sky 1.2 times from 2010 January 7 to August 6), the 3-Band Cryogenic survey (first three wavebands, 30 per cent of the sky from 2010 August 6 to September 29), and the NEOWISE post-cryogenic survey (first two wavebands, covering 70 per cent of the sky from 2010 September 20 to 2011 February 1). (1 data file).

  10. An RR Lyrae period shift in terms of the Fourier parameter Phi sub 31

    NASA Technical Reports Server (NTRS)

    Clement, Christine M.; Jankulak, Michael; Simon, Norman R.

    1992-01-01

    The Fourier phase parameter Phi sub 31 has been determined for RRc stars in five globular clusters, NGC 6171, M5, M3, M53, and M15. The results indicate that the RRc stars in a given cluster show a sequence of Phi sub 31 increasing with period, and that the higher the cluster metallicity, the higher the sequence lies in a plot of Phi sub 31 with period. The Phi sub 31 values for the stars in NGC 6171 and M5 presented here are based on observations made with the University of Toronto 0.61 m telescope at Las Campanas, Chile, while those for M3, M53, and M15 are based on published data. A bootstrap procedure has been used to establish the uncertainties in the Fourier parameters. The physical significance of the relationship among Phi sub 31, period, and metallicity is not yet understood. It will need to be tested with hydrodynamic pulsation models computed with new opacities.

  11. RR Lyrae stars and the horizontal branch of NGC 5904 (M5)

    NASA Astrophysics Data System (ADS)

    Arellano Ferro, A.; Luna, A.; Bramich, D. M.; Giridhar, Sunetra; Ahumada, J. A.; Muneer, S.

    2016-05-01

    We report the distance and [Fe/H] value for the globular cluster NGC 5904 (M5) derived from the Fourier decomposition of the light curves of selected RRab and RRc stars. The aim in doing this was to bring these parameters into the homogeneous scales established by our previous work on numerous other globular clusters, allowing a direct comparison of the horizontal branch luminosity in clusters with a wide range of metallicities. Our CCD photometry of the large variable star population of this cluster is used to discuss light curve peculiarities, like Blazhko modulations, on an individual basis. New Blazhko variables are reported.

  12. An extensive photometric study of the Blazhko RR Lyrae star RZ Lyr

    NASA Astrophysics Data System (ADS)

    Jurcsik, J.; Sódor, Á.; Hajdu, G.; Szeidl, B.; Dózsa, Á.; Posztobányi, K.; Smitola, P.; Belucz, B.; Fehér, V.; Kővári, Zs.; Kriskovics, L.; Kun, E.; Molnár, L.; Nagy, I.; Vida, K.; Görög, N.

    2012-06-01

    The analysis of recent, extended multicolour CCD and archive photoelectric, photographic and visual observations has revealed several important properties of RZ Lyr, an RRab-type variable exhibiting large-amplitude Blazhko modulation. On the time base of ˜110 yr, a strict anticorrelation between the pulsation- and modulation-period changes is established. The light curve of RZ Lyr shows a remarkable bump on the descending branch in the small-amplitude phase of the modulation, similarly to the light curves of bump Cepheids. We speculate that the stellar structure temporally suits a 4:1 resonance between the periods of the fundamental and one of the higher order radial modes in this modulation phase. The light-curve variation of RZ Lyr can be correctly fitted with a two-modulation-component solution; the 121-d period of the main modulation is nearly but not exactly four times longer than the period of the secondary modulation component. Using the inverse photometric method, the variations in the pulsation-averaged values of the physical parameters in different phases of both modulation components are determined. Based on observations collected primarily with the automatic 60-cm telescope of Konkoly Observatory, Budapest, Svábhegy.

  13. A preliminary study of the RR Lyrae stars observed in K2 Campaign 3

    NASA Astrophysics Data System (ADS)

    Juhasz, A. L.; Molnar, L.; Plachy, E.

    2016-05-01

    We have started a comprehensive analysis of the Kepler K2 Field 3 data set. Our goals are to assess the statistics of the sample, and to search for peculiar stars. We found a candidate triple-mode RRab star, where the first and ninth overtones also seem to be excited.

  14. VizieR Online Data Catalog: QUEST RR Lyrae Survey III. Low Galactic latitude (Mateu+, 2012)

    NASA Astrophysics Data System (ADS)

    Mateu, C.; Vivas, A. K.; Downes, J. J.; Briceno, C.; Zinn, R.; Cruz-Diaz, G.

    2013-09-01

    The present survey spans a total area of 476 deg2 and makes archive observations obtained between late 1998 and mid-2008 with the QUEST camera and the 1.0/1.5-m Jurgen Stock Schmidt telescope at the NOV in Llano del Hato, Venezuela. (4 data files).

  15. An unusually very bright dust light mass (?) observed in the vicinity (?) of á Lyrae

    NASA Astrophysics Data System (ADS)

    Stefanopoulos, G.

    2009-04-01

    There are not many written worldwide references regarding unusual phenomena such as dust, unusual lights or unexplained objects orbiting the earth or the solar and extra solar systems. Regarding the external space few references exist . Regarding the a Lyrae many scientists were involve in the eighties with the possible existence of a planet next to this star. Structure in the Dusty Debris around Vega, D. J. Wilner et al 2002 ApJ 569.Near-infrared observations of Vega, at 2006 Philip M. Hinz et al. refers to possible companion planet round this star .In constellations Lyrae and Eridani,some authors refer to possible initial formation of planets and they mention the presence of dust formations orbiting around those stars.(A. N. Heinze, Philip M. Hinz, Deep L' and M-band Imaging for Planets Around Vega and epsilon Eridani,The Astrophysical Journal 688 (2008) 583. This paper is concerned with an unexplained or perhaps portion of dust, in the constellation of Lyrae, which appears and have been observed only in conventional photographic plaque.For this observation , simple equipment and amateur instruments are use.In the night of April the 2002, during an amatory observation in variable stars, in the RR Lyrae, pictures were taken in the mentioned deep space area as a normal weekly study procedure. The instruments used are, telescope Meade 10΄΄, illuminate reticle guiding, 12mm, photo camera Nikon F -100, and lenses,70mm, f =1,8.The film used was a Kodak X-pro,BW 400 ASA.The equatorial mount was motorized. A total of six pictures with an exposure 5-10 min were taken. While developing the film, on the fifth photogram, a bright (object?) - dust light appear which seems to be in adhesion with the Vega star . On consecutive months more pictures were taken, with conventional and digital exposures, without any repetition of the event. What is provoke illumination of this dust portion to have been present in a simple photographic film? This simple observation study is

  16. Discovery of a shell around Alpha Lyrae

    NASA Technical Reports Server (NTRS)

    Aumann, H. H.; Beichman, C. A.; Gillett, F. C.; De Jong, T.; Houck, J. R.; Low, F. J.; Neugebauer, G.; Walker, R. G.; Wesselius, P. R.

    1984-01-01

    IRAS observations of Alpha Lyrae reveal a large infrared excess beyond 12 microns. The excess over an extrapolation of a 10,000 K blackbody is a factor of 1.3 at 25 microns, 7 at 60 microns, and 16 at 100 microns. The source of 60 microns emission has a diameter of about 20 arcsec. This is the first detection of a large infrared excess from a main-sequence star without significant mass loss. The most likely origin of the excess is thermal radiation from solid particles more than a millimeter in radius, located approximately 85 AU from Alpha Lyr and heated by the star to an equilibrium temperature of 85 K. These results provide the first direct evidence outside of the solar system for the growth of large particles from the residual of the prenatal cloud of gas and dust.

  17. The ultraviolet spectrum of Beta Lyrae

    NASA Technical Reports Server (NTRS)

    Mazzali, Paolo A.

    1987-01-01

    The high-resolution UV spectrum of Beta Lyrae observed with the IUE satellite between 1980 and 1986 is analyzed. A complete list of line identifications for the entire spectral range of the IUE (1225-3125 A) is presented. The main spectral features are P Cygni profiles of resonance lines of high ionization states typical of stellar winds, some of which are combined with a broad emission feature due probably to an accretion disk; P Cygni profiles due to moderately ionized atoms in the iron group (mostly Fe III and Ni III); and absorption lines of elements in lower ionization stages, such as S II, Si II (higher multiplets), Ni II, and a large number of Fe II lines.

  18. LYRA, a webserver for lymphocyte receptor structural modeling

    PubMed Central

    Klausen, Michael Schantz; Anderson, Mads Valdemar; Jespersen, Martin Closter; Nielsen, Morten; Marcatili, Paolo

    2015-01-01

    The accurate structural modeling of B- and T-cell receptors is fundamental to gain a detailed insight in the mechanisms underlying immunity and in developing new drugs and therapies. The LYRA (LYmphocyte Receptor Automated modeling) web server (http://www.cbs.dtu.dk/services/LYRA/) implements a complete and automated method for building of B- and T-cell receptor structural models starting from their amino acid sequence alone. The webserver is freely available and easy to use for non-specialists. Upon submission, LYRA automatically generates alignments using ad hoc profiles, predicts the structural class of each hypervariable loop, selects the best templates in an automatic fashion, and provides within minutes a complete 3D model that can be downloaded or inspected online. Experienced users can manually select or exclude template structures according to case specific information. LYRA is based on the canonical structure method, that in the last 30 years has been successfully used to generate antibody models of high accuracy, and in our benchmarks this approach proves to achieve similarly good results on TCR modeling, with a benchmarked average RMSD accuracy of 1.29 and 1.48 Å for B- and T-cell receptors, respectively. To the best of our knowledge, LYRA is the first automated server for the prediction of TCR structure. PMID:26007650

  19. The variability of RR Tel

    NASA Astrophysics Data System (ADS)

    Heck, A.; Manfroid, J.

    1982-12-01

    Photometric measurements of RR Tel performed at ESO are discussed. RR Tel is a galactic nova which has been associated with a sole outburst, observed in 1944. The photometric observations were made in the ubvy system in August 1981, when a strong brightening was detected in V. IUE data subjected to a Fourier analysis indicate that the object has a period within 5 days of 395 days. Measurements of brightening of the J component also yield a period of 390 days. The presence of a Mira variable is considered, noting the supporting evidence from H2O and TiO spectral bands, but equally the lack of IR data until after 1960. It is suggested that data from before 1944 indicate that modulated bursts of mass transfer and accompanying accretion events preceeded the outburst of the underlying binary star, which could be a link between dwarf novae, classical novae, and symbiotic stars.

  20. Nature of the secondary component of beta Lyrae.

    NASA Technical Reports Server (NTRS)

    Stothers, R.; Lucy, L. B.

    1972-01-01

    Development of a hypothesis concerning the nature of the secondary component of beta Lyrae which is regarded as more plausible than the suggestion that this component is a black hole. Adopting Huang's (1962) and Woolf's (1965) basic model for beta Lyrae, it is suggested that the secondary star may be a massive 'main-sequence' star in rapid, nonuniform motion. Certain findings regarding mu Sco and V356 Sgr, which have primaries that are very cool and underluminous for their masses, are cited as evidence for such an inference, since their underluminosity is probably due to high angular momentum and they are normal enough not to be suspected of harboring a black hole.

  1. Spectral Lines Profiles of Be Star: Beta Lyrae

    NASA Astrophysics Data System (ADS)

    Ahmad, N.; Zainuddin, Mohd. Z. Yahya, Mohd. S.

    2009-08-01

    The variation of spectral lines profiles has been studies on Beta Lyrae based on the data from Jun to Sept. 1999 taken from Ritter Observatory. The V/R between the violet and red intensity peaks of Halpha ratio radial velocity show the violet-shifting and the comparison on spectral profile with data taken in 2007 at Langkawi National Observatory shows some changes.

  2. The hot white dwarf in the cataclysmic variable MV Lyrae

    NASA Technical Reports Server (NTRS)

    Hoard, D. W.; Linnell, A. P.; Szkody, Paula; Fried, Robert E.; Sion, Edward M.; Hubeny, Ivan; Wolfe, M. A.

    2003-01-01

    We have obtained the first far-ultraviolet spectrum of the novalike cataclysmic variable MV Lyrae using the Far Ultraviolet Spectroscopic Explorer. We also obtained contemporaneous optical light curves and spectra. All data are from a deep faint accretion state of MV Lyr.

  3. Observations of Epsilon Lyrae by the Video Drift Method

    NASA Astrophysics Data System (ADS)

    Wasson, Rick; Nelson, Nancy; Nelson, Eric; Buehlman, William; Wilson, Earl; Zapata, Deanna

    2015-01-01

    The major components of the famous "double-double" star Epsilon Lyrae, STF2382AB and STF2383CD, were measured by the Video Team at the Apple Valley Double Star Workshop in 2013, using the Video Drift Method. The results are in reasonable agreement with other recent measures and predictions of the latest orbital solutions.

  4. Complex infrared emission features in the spectrum of beta Lyrae

    NASA Technical Reports Server (NTRS)

    Morgan, T. H.; Potter, A. E.; Kondo, Y.

    1974-01-01

    Spectra of beta Lyrae over the spectral region from 5800 to 11,000 per cm (1.76 to 0.9 micron) at two different phases have been obtained. They show a remarkable emission-absorption complex at 9231 per cm, a highly structured emission at P beta, and several additional broad weak emissions.

  5. Drosophila Lyra mutations are gain-of-function mutations of senseless.

    PubMed Central

    Nolo, R; Abbott, L A; Bellen, H J

    2001-01-01

    The Lyra mutation was first described by Jerry Coyne in 1935. Lyra causes recessive pupal lethality and adult heterozygous Lyra mutants exhibit a dominant loss of the anterior and posterior wing margins. Unlike many mutations that cause loss of wing tissue (e.g., scalloped, Beadex, cut, and apterous-Xasta), Lyra wing discs do not exhibit increased necrotic or apoptotic cell death, nor do they show altered BrdU incorporation. However, during wing disc eversion, loss of the anterior and posterior wing margins is apparent. We have previously shown that senseless, a gene that is necessary and sufficient for peripheral nervous system (PNS) development, is allelic to Lyra. Here we show by several genetic criteria that Lyra alleles are neomorphic alleles of senseless that cause ectopic expression of SENSELESS in the wing pouch. Similarly, overexpression of SENSELESS in the wing disc causes loss of wing margin tissue, thereby mimicking the Lyra phenotype. Lyra mutants display aberrant expression of DELTA, VESTIGIAL, WINGLESS, and CUT. As in Lyra mutants, overexpression of SENSELESS in some areas of the wing pouch also leads to loss of WINGLESS and CUT. In summary, our data indicate that overexpression of SENSELESS causes a severe reduction in NOTCH signaling that in turn may lead to decreased transcription of several key genes required for wing development, leading to a failure in cell proliferation and loss of wing margin tissue. PMID:11139511

  6. Drosophila Lyra mutations are gain-of-function mutations of senseless

    NASA Technical Reports Server (NTRS)

    Nolo, R.; Abbott, L. A.; Bellen, H. J.

    2001-01-01

    The Lyra mutation was first described by Jerry Coyne in 1935. Lyra causes recessive pupal lethality and adult heterozygous Lyra mutants exhibit a dominant loss of the anterior and posterior wing margins. Unlike many mutations that cause loss of wing tissue (e.g., scalloped, Beadex, cut, and apterous-Xasta), Lyra wing discs do not exhibit increased necrotic or apoptotic cell death, nor do they show altered BrdU incorporation. However, during wing disc eversion, loss of the anterior and posterior wing margins is apparent. We have previously shown that senseless, a gene that is necessary and sufficient for peripheral nervous system (PNS) development, is allelic to Lyra. Here we show by several genetic criteria that Lyra alleles are neomorphic alleles of senseless that cause ectopic expression of SENSELESS in the wing pouch. Similarly, overexpression of SENSELESS in the wing disc causes loss of wing margin tissue, thereby mimicking the Lyra phenotype. Lyra mutants display aberrant expression of DELTA, VESTIGIAL, WINGLESS, and CUT. As in Lyra mutants, overexpression of SENSELESS in some areas of the wing pouch also leads to loss of WINGLESS and CUT. In summary, our data indicate that overexpression of SENSELESS causes a severe reduction in NOTCH signaling that in turn may lead to decreased transcription of several key genes required for wing development, leading to a failure in cell proliferation and loss of wing margin tissue.

  7. Thermal evolution of flares observed by PROBA2/LYRA

    NASA Astrophysics Data System (ADS)

    Dammasch, Ingolf; Kretzschmar, Matthieu; Chamberlin, Phillip; Dominique, Marie

    2012-07-01

    Evaluating the solar impact on Earth climate requires knowledge of variations in the Solar Spectral Irradiance. LYRA is a UV-VUV solar radiometer embarked on ESA's PROBA2 mission. The instrument acquires solar irradiance in four broad spectral regions - from soft X-ray to UV - that have been chosen for their relevance in solar physics, space weather, and aeronomy. Analysis of LYRA time series of flares showed that the flare rise phase is dominated by soft X-ray, whereas the flare decline phase takes longer than this and seems to be dominated by cooler EUV emission. Using data monitored by GOES and SDO/EVE, we will try to understand the quantitative relationship of these spectral intervals.

  8. Copernicus spectra of beta Lyrae. [in far UV

    NASA Technical Reports Server (NTRS)

    Hack, M.; Hutchings, J. B.; Kondo, Y.; Mccluskey, G. E.; Plavec, M.; Polidan, R. S.

    1974-01-01

    The observations reported were made in August and September 1973. The principal data were scans in the low resolution mode at phases nearly coincident with the two light minima. Shorter scans were obtained at the two quadrature phases. The data show that the secondary component of beta Lyrae is a hotter object than the visible B8 star. The velocity amplitude of the lines suggests that the secondary is the more massive object, by a factor of several times.

  9. VizieR Online Data Catalog: Leo P RR Lyrae candidates & cumulative SFH (McQuinn+, 2015)

    NASA Astrophysics Data System (ADS)

    McQuinn, K. B. W.; Skillman, E. D.; Dolphin, A.; Cannon, J. M.; Salzer, J. J.; Rhode, K. L.; Adams, E. A. K.; Berg, D.; Giovanelli, R.; Girardi, L.; Haynes, M. P.

    2016-02-01

    HST observations of Leo P were obtained using the Advance Camera for Surveys (ACS) instrument in the F475W (Sloan g) and F814W (I) filters between 2014 April 23 and 26 (GO 13376; PI McQuinn). (3 data files).

  10. The Baade-Wesselink method applied to field RR Lyrae stars. II - SW Andromedae, SW Draconis, and SS Fornacis

    NASA Technical Reports Server (NTRS)

    Cacciari, C.; Clementini, G.; Prevot, L.; Buser, R.

    1989-01-01

    The Baade-Wesselink method has been combined with previous photometry and radial velocities to yield distances of 520 + or - 50 pc, 840 + or - 50 pc, and 780 + or - 150 pc, and mean absolute magnitudes of 0.88 + or - 0.20, 0.86 + or - 0.20, and 0.73 + or - 0.50, for SW And, SW Dra, and SS For, respectively. The present technique is able to account for the problem of phase-lag between spectroscopically and photometrically determined radial displacements in SW Dra, the Blazhko effect in SW And, and both the phase-lag and Blazhko effects in SS For.

  11. On the interpretation of the Sandage period-shift effect among globular-cluster RR Lyrae variables

    NASA Technical Reports Server (NTRS)

    Sweigart, Allen V.; Renzini, Alvio; Tornambe, Amedeo

    1987-01-01

    A new grid of canonical zero-age horizontal branch (ZAHB) models is constructed to study the Sandage period-shift effect, and a number of possible explanations for the discrepancy between the observed and predicted period shifts are explored. Various factors which determine the period shift in ZAHB models are discussed in detail, showing that possible uncertainties in the input physics used for computing the preceding red-giant evolution are unlikely to resolve the discrepancy. Some test calculations for the ZAHB phase are presented which suggest than an increase in the metal opacity at temperatures around a million K might substantially increase the predicted period shift. It is found that a nonsolar CNO to Fe ratio is not a plausible explanation of the period-shift discrepancy, and the effects of evolution off the ZAHB in the period-effective temperature diagram are discussed. It is shown that evolution can increase the predicted period shift but not to the extent required by the Sandage effect. The possibility that rotation might explain the discrepancy is considered and rejected.

  12. First detection of multi-shocks in RR Lyrae stars from Antarctica : A possible explanation of the Blazhko effect

    SciTech Connect

    Chadid, M.; Vernin, J.; Zalian, C.; Pouzenc, C.; Abe, L.; Agabi, A.; Aristidi, E.; Mékarnia, D.; Preston, G.; Liu, L.Y.; Trinquet, H.

    2014-11-01

    We present the first detection of multi-shocks propagating through the atmosphere of the Blazhko star S Arae using uninterrupted, accurate optical photometric data collected during one polar night, 150 days from Antarctica at Dome C, with the Photometer AntarctIca eXtinction (PAIX). We acquired 89,736 CCD frames during 323 pulsation cycles and 3 Blazhko cycles. We detected two new light curve properties in the PAIX light curve, jump and rump, which we associated with two new post-maximum shock waves Sh{sub PM1} and Sh{sub PM2}. jump, lump, rump, bump, and hump are induced by five shock waves, with different amplitudes and origins, Sh{sub PM1}, Sh{sub PM}, Sh{sub PM2}, Sh{sub PM3}, and the main shock Sh{sub H+He}. Correlations between the length of rise time and light amplitude and Sh{sub PM3} are monotonous during three Blazhko cycles, but the pulsation curve is double peaked. We discuss the physical mechanisms driving the modulation of these quantities. Finally, we hypothesize that the origin of the Blazhko effect is a dynamical interaction between a multi-shock structure and an outflowing wind in a coronal structure.

  13. Lichtkurve und Periode des RR-Lyrae-Sterns TV Trianguli und GSC 02297-00060, ein neuer Veraenderlicher im Feld

    NASA Astrophysics Data System (ADS)

    Groebel, Rainer

    2014-03-01

    Based on data from the SWASP database and on recent observations 21 maxima and 12 minima timings of the little studied star TV Tri could be derived. It is shown that since the discovery the period remains essentially constant. The light curve shows only slight variations with a hump in the ascending branch. An improved ephemeris HJD (max.) = 2447385.354(5) + 0.7057324(5) x E is given. It turned out that the nearby suspected variable NSV 15327 (GSC 2.3 NBXY006220, 1:33:24.96 +32:27:39.10) remained constant in the observation period. It could be shown that the star GSC 02297-00060 (1:32:54.08 +32:29:34.85) also present in the field, is a short period eclipsing variable with shallow eclipses of 0.1 mag amplitude with the ephemeris HJD (min.) = 2456220.5180(16) + 0.2556919(14) x E. Rainer Groebel is a member of the BAV.

  14. VizieR Online Data Catalog: QSOs and RR Lyrae in Pan-STARRS1 3π Data (Hernitschek+ 2016)

    NASA Astrophysics Data System (ADS)

    Hernitschek, N.; Schlafly, E. F.; Sesar, B.; Rix, H.-W.; Hogg, D. W.; Ivezic, Z.; Grebel, E. K.; Bell, E. F.; Martin, N. F.; Burgett, W. S.; Flewelling, H.; Hodapp, K. W.; Kaiser, N.; Magnier, E. A.; Metcalfe, N.; Wainscoat, R. J.; Waters, C.

    2016-04-01

    In area and depth, the Pan-STARRS1 (PS1) 3π survey is unique among many-epoch, multi-band surveys and has enormous potential for the all-sky identification of variable sources. PS1 has observed the sky typically seven times in each of its five bands (grizy) over 3.5 years, but unlike SDSS, not simultaneously across the bands. We developed a new approach for quantifying statistical properties of non-simultaneous, sparse, multi-color light curves through light curve structure functions, effectively turning PS1 into a {sim}35-epoch survey. We use this approach to estimate variability amplitudes and timescales for point sources brighter than rP1=21.5 mag in the survey. On this basis we provide a catalog of all likely variable point sources and likely QSOs in PS1. (2 data files).

  15. GEOMETRICAL CONSTRAINTS ON THE HOT SPOT IN BETA LYRAE

    SciTech Connect

    Lomax, Jamie R.; Hoffman, Jennifer L.; Elias II, Nicholas M.; Bastien, Fabienne A.; Holenstein, Bruce D. E-mail: Jennifer.Hoffman@du.edu E-mail: fabienne.a.bastien@vanderbilt.edu

    2012-05-01

    We present results from six years of recalibrated and new spectropolarimetric data taken with the University of Wisconsin's Half-Wave Spectropolarimeter and six years of new data taken with the photoelastic modulating polarimeter at the Flower and Cook Observatory of beta Lyrae. Combining these data with polarimetric data from the literature allows us to characterize the intrinsic BVRI polarized light curves. A repeatable discrepancy of 0.245 days (approximately 6 hr) between the secondary minima in the total light curve and the polarization curve in the V band, with similar behavior in the other bands, may represent the first direct evidence for an accretion hot spot on the disk edge.

  16. LYRA Observations of Two Oscillation Modes in a Single Flare

    NASA Astrophysics Data System (ADS)

    Van Doorsselaere, T.; De Groof, A.; Zender, J.; Berghmans, D.; Goossens, M.

    2011-10-01

    We analyze light curves from the LYRA irradiance experiment on board PROBA2 during the flare of 2010 February 8. We see both long- and short-period oscillations during the flare. The long-period oscillation is interpreted in terms of standing slow sausage modes; the short-period oscillation is thought to be a standing fast sausage mode. The simultaneous presence of two oscillation modes in the same flaring structure allows for new coronal seismological applications. The periods are used to find seismological estimates of the plasma-β and the density contrast of the flaring loop. Also the wave mode number is estimated from the observed periods.

  17. Geometrical Constraints on the Hot Spot in Beta Lyrae

    NASA Astrophysics Data System (ADS)

    Lomax, Jamie R.; Hoffman, Jennifer L.; Elias, Nicholas M., II; Bastien, Fabienne A.; Holenstein, Bruce D.

    2012-05-01

    We present results from six years of recalibrated and new spectropolarimetric data taken with the University of Wisconsin's Half-Wave Spectropolarimeter and six years of new data taken with the photoelastic modulating polarimeter at the Flower and Cook Observatory of beta Lyrae. Combining these data with polarimetric data from the literature allows us to characterize the intrinsic BVRI polarized light curves. A repeatable discrepancy of 0.245 days (approximately 6 hr) between the secondary minima in the total light curve and the polarization curve in the V band, with similar behavior in the other bands, may represent the first direct evidence for an accretion hot spot on the disk edge.

  18. LYRA on-board PROBA2: instrument performances and latest results

    NASA Astrophysics Data System (ADS)

    Dominique, Marie; Kretzschmar, Matthieu; Dammasch, Ingolf

    2012-07-01

    LYRA, is the Large Yield Radiometer embarked on the European Space Agency Proba2 mission that was launched on 2 November 2009 (http://proba2.sidc.be). LYRA acquires solar irradiance measurements in four broad spectral channels from the soft X-ray to the middle ultraviolet at high cadence (nominally 20 Hz). In this talk, we briefly describe the instrument and detail its current status (performances of its innovative wide-bandgap detectors, degradation, comparison to other missions). We also provide an overview of the main fields of research currently under investigation by the LYRA consortium and present the latest results achieved.

  19. Detection of Solar Rotational Variability in the Large Yield RAdiometer (LYRA) 190 - 222 nm Spectral Band

    NASA Astrophysics Data System (ADS)

    Shapiro, A. V.; Shapiro, A. I.; Dominique, M.; Dammasch, I. E.; Wehrli, C.; Rozanov, E.; Schmutz, W.

    2013-08-01

    We analyze the variability of the spectral solar irradiance during the period from 7 January 2010 until 20 January 2010 as measured by the Herzberg channel (190 - 222 nm) of the Large Yield RAdiometer (LYRA) onboard PROBA2. In this period of time, observations by the LYRA nominal unit experienced degradation and the signal produced by the Herzberg channel frequently jumped from one level to another. Both factors significantly complicate the analysis. We present the algorithm that allowed us to extract the solar variability from the LYRA data and compare the results with SORCE/SOLSTICE measurements and with modeling based on the Code for the Solar Irradiance (COSI).

  20. Variable Stars in the Unusual, Metal-Rich Globular Cluster NGC-6441

    NASA Technical Reports Server (NTRS)

    Pritzl, Barton J.; Smith, Horace A.; Catelan, Marcio; Sweigart, Allen V.; Fisher, Richard R. (Technical Monitor)

    2001-01-01

    We have undertaken a search for variable stars in the metal-rich globular cluster NGC 6441 using time-series BV photometry. The total number of variables found near NGC 6441 has been increased to approx. 104, with 48 new variables being found in this survey. A significant number of the variables are RR Lyrae stars (approx. 46), most of which are probable cluster members. As was noted by Layden et al. (1999), the periods of the fundamental mode RR Lyrae are unusually long compared to field stars of similar metallicity. The existence of these long period RRab stars is consistent with Sweigart & Catelan's (1998) prediction that the horizontal branch of NGC 6441 is unusually bright. This result implies that the metallicity-luminosity relationship for RR Lyrae stars is not universal. We discuss the difficulty in determining the Oosterhoff classification of NGC 6441 due to the unusual nature of its RR Lyrae. A number of ab-type RR Lyrae are found to be both brighter and redder than the other probable RRab found along the horizontal branch, which may be a result of blending with stars of redder color. A smaller than usual gap is found between the shortest period fundamental mode and the longest period first-overtone mode RR Lyrae. We determine the reddening of the cluster to be E(B - V) = 0.51 +/- 0.02 mag, with substantial differential reddening across the face of the cluster. The mean V magnitude of the RR Lyrae is found to be 17.51 +/- 0.02 resulting in a distance of 10.4 to 11.9 kpc, for a range of assumed values of < M(sub V)> for RR Lyrae stars. The possibility that stars in NGC 6441 may span a range in [Fe/H] is also discussed.

  1. A search for Lyman-alpha emission in beta Lyrae from Copernicus

    NASA Technical Reports Server (NTRS)

    Kondo, Y.; Mccluskey, G. E., Jr.

    1974-01-01

    High-resolution (0.2 A) spectrophotometric observations of the complex eclipsing binary beta Lyrae were obtained with the Princeton Telescope Spectrometer on the Copernicus satellite. We discuss the search for L-alpha emission in beta Lyrae and compare the Copernicus results with the OAO-2 observations of the same binary system. The possible L-alpha emission features observed from OAO-2 are identified as blends of the emission lines of other elements in the vicinity of L-alpha.

  2. Interacting extended Chaplygin gas cosmology in Lyra manifold

    NASA Astrophysics Data System (ADS)

    Khurshudyan, Martiros

    2015-12-01

    Subject of our interest is an extended Chaplygin gas cosmology and new receipts providing accelerated expansion of the large scale universe. In Literature a variety of cosmological models exist studying the behavior of the universe in the presence of Chaplygin gas. From its initial form Chaplygin gas evolved and accepted different EoS-s and we will work with one of them. The main purpose of this work is to study behavior of the universe in Lyra Manifold with a varying \\varLambda-term, which does give us modified field equations. Modified field equations compared to field equations of General Relativity provide a new parametrization of dark energy sector of the large scale universe. It is also interesting to study the behavior of the universe in case of an existing coupling between quintessence DE and extended Chaplygin gas. We applied observational constraints and causality issue to separate physically relevant behavior of the phenomenological model.

  3. High temperature plasma in beta Lyrae, observed from Copernicus

    NASA Technical Reports Server (NTRS)

    Kondo, Y.; Hack, M.; Hutchings, J. B.; Mccluskey, G. E., Jr.; Plavec, M.; Polidan, R. S.

    1975-01-01

    High-resolution UV spectrophotometry of the complex close binary system beta Lyrae was performed with a telescope spectrometer on board Copernicus. Observations were made at phases 0.0, 0.25, 0.5, and 0.75 with resolutions of 0.2 A (far-UV) and 0.4 A (mid-UV). The far-UV spectrum is completely dominated by emission lines indicating the existence of a high-temperature plasma in this binary. The spectrum of this object is unlike that of any other object observed from Copernicus. It is believed that this high-temperature plasma results from dynamic mass transfer taking place in the binary. The current results are compared with OAO-2 observations and other observational results. The possibility that the secondary component is a collapsed object is also discussed; the Copernicus observations are consistent with the hypothesis that the spectroscopically invisible secondary component is a black hole.

  4. Narrow-band photometry of Beta Lyrae in 1971

    NASA Astrophysics Data System (ADS)

    Scarfe, C. D.

    1980-01-01

    Observations of Beta Lyrae (with HR 6997 as the principal companion star) are presented, principally of certain strong lines and neighboring continuum regions obtained through interference filters of bandwidths ranging from 27.0 to 33.7 A. Light curves in the 3 blue and 3 red bands are shown, and color indices and emission intensity indices are tabulated. Moreover, a photometric index of emission line strength, analogous to the spectroscopic index of Batten and Sahade (1973), is derived. It is suggested that the H alpha emission comes from a larger region around the binary star than does the helium emission and is asymmetrical, being weakest near quadrature when the primary star is approaching earth. The helium emission, by contrast, is more symmetrical, and varies with binary phase by a larger fractional amount.

  5. Tectonic Setting of the Lyra Basin, west of the Ontong Java Plateau

    NASA Astrophysics Data System (ADS)

    Nakanishi, M.; Sano, T.; Shimizu, K.

    2007-12-01

    We present the preliminary results of the geophysical investigation and rock sampling in the Lyra Basin, the deep ocean basin west of the Ontong Java Plateau. The Ontong Java Plateau (OJP) is one of the most voluminous large igneous provinces. The evidences from drilling samples indicate that most of the OJP formed rapidly about 120 Ma at mid-southern latitude in the Pacific Basin. Deep ocean basins are contiguous with the OJP. For settlement of the argument about the origin of the OJP, the tectonic setting of the deep ocean basins around the OJP must be revealed. Tectonic histories of the Nauru, East Mariana, and Pigafetta basins, were revealed using the Mesozoic magnetic anomaly lineations. That of Lyra basin is, however, still unknown because of lack of magnetic anomaly lineations. The depth of the seafloor in the Lyra Basin deepens west, from 4000 to 5000 m. The Lyra Trough, crossing the Lyra Basin, is a broad and deep graben. In December 2006, we conducted the geophysical investigation and rock sampling in the Lyra Basin using R/V KAIREI, Japan Agency for Marine-Earth Science and Technology. Our bathymetric measurement revealed the topographic expression of the Lyra Trough. The depth of the trough is around 5500 m. The bottom of the trench as a whole is very smooth except for several lineated ridges. The height of the lineated ridges is about 500 m. The length of the lineated ridges is around 20 km. The strike of some ridges is N35°W and parallel to the trough strike. That of others is N50°W and oblique to the trough strike. Seamounts are located in the eastern rim of the Lyra Trough south of 1°30'N. The height of the seamounts is more than 2500 m. We obtained volcanic samples from the lineated ridge in the Lyra Trough and the seamount in the eastern rim of the trough. Most of igneous rocks are volcanic breccia, being coated by thick Mn crust. Although many volcanoclastic rocks are highly altered, some fresh samples were recovered. They are olivine

  6. Progress Towards Understanding the Degradation and Performance Characteristics of the PROBA2-LYRA Instrument

    NASA Astrophysics Data System (ADS)

    Jones, A. R.; McMullin, D. R.; Dominique, M.; Dammasch, I.

    2013-12-01

    The Large Yield Radiometer, LYRA is a solar radiometer on the ESA PROBA2 spacecraft launched November 2, 2009. LYRA has been designed to provide measurements of the solar XUV to MUV (soft X-ray to middle ultraviolet) region of the solar spectrum. The LYRA instrument observes in four broad spectral channels, from soft X-ray to UV, chosen for their relevance to solar physics and space weather. Each of the four channels has the capability of acquiring irradiance measurements at a nominal cadence of 20 Hz, but can be increased to 100 Hz. Each of the four channels has suffered from significant degradation almost immediately after launch. The degradation observed in the LYRA channels is significant and detrimental to the potential science. Preliminary work in this effort has shown that the most likely cause of the observed degradation is contaminant buildup on the filters at the front of the instrument. In this work, we present initial results of our investigation into the performance characteristics and observed degradation. We have developed and will present results from our three-step approach: 1. Develop models for each LYRA channel using measured calibrations and instrument design parameters; 2. Use the models to estimate the sensitivity changes due to possible degradation sources (thickness and composition); 3. Evaluate corrected sensor performance by comparing the measured data with independent measurements from currently operating instruments.

  7. The pulsating variable star population in DDO210

    NASA Astrophysics Data System (ADS)

    Ordoñez, Antonio J.; Sarajedini, Ata

    2016-01-01

    We have probed the pulsating variable star content of the isolated Local Group dwarf galaxy, DDO210 (Aquarius), using archival Advanced Camera for Surveys/Hubble Space Telescope imaging in the F475W and F814W passbands. We find a total of 32 RR Lyrae stars (24 ab-type; 8 c-type) and 75 Cepheid variables. The mean periods of the ab-type and c-type RR Lyrae stars are calculated to be = 0.609 ± 0.011 and = 0.359 ± 0.025 d, respectively. The light-curve properties of the fundamental mode RR Lyrae stars yield a mean metallicity of <[Fe/H]> = -1.63 ± 0.11 dex for this ancient population, consistent with a recent synthetic colour-magnitude diagram analysis. We find this galaxy to be Oosterhoff-intermediate and lacking in high-amplitude, short-period ab-type RR Lyrae, consistent with behaviour recently observed for many dwarf spheroidals and ultrafaint dwarfs in the Local Group. We find a distance modulus of μ = 25.07 ± 0.12 as determined by the RR Lyrae stars, slightly larger but agreeing with recent distance estimates from the red giant branch tip. We also find a sizable population of Cepheid variables in this galaxy. We provide evidence in favour of most if not all of these stars being short-period classical Cepheids. Assuming all of these stars to be classical Cepheids, we find that most of these Cepheids are ˜300 Myr old, with the youngest Cepheids being offset from the older Cepheids and the centre of the galaxy. We conclude that this may have resulted from a migration of star formation in DDO210.

  8. Mira's role in RR Tel revisited

    NASA Astrophysics Data System (ADS)

    Heck, A.; Manfroid, J.

    The present uvby data, IUE FES measurements and American Association of Variable Star Observers visual estimates of the very slow nova RR Tel show that the object has gone through periodic variations in visual light since it started fading in 1949 after the outburst it incurred in 1944. The period is, however, not constant, and varies between 350 and 410 days, confirming Mayall's (1957) statement and contradicting the conclusions of later investigators. Synchronized variations of a Mira in the infrared and of a blue component indicate that the Mira mass outflow probably varies in a phase with its pulsations. Large variations occur in visual light on a time scale of a few weeks.

  9. STELLAR ARCHEOLOGY IN THE GALACTIC HALO WITH ULTRA-FAINT DWARFS. VII. HERCULES

    SciTech Connect

    Musella, Ilaria; Ripepi, Vincenzo; Marconi, Marcella E-mail: ripepi@na.astro.it; and others

    2012-09-10

    We present the first time-series study of the ultra-faint dwarf galaxy Hercules. Using a variety of telescope/instrument facilities we secured about 50 V and 80 B epochs. These data allowed us to detect and characterize 10 pulsating variable stars in Hercules. Our final sample includes six fundamental-mode (ab-type) and three first-overtone (c-type) RR Lyrae stars, and one Anomalous Cepheid. The average period of the ab-type RR Lyrae stars, (P{sub ab}) = 0.68 days ({sigma} = 0.03 days), places Hercules in the Oosterhoff II group, as found for almost the totality of the ultra-faint dwarf galaxies investigated so far for variability. The RR Lyrae stars were used to obtain independent estimates of the metallicity, reddening, and distance to Hercules, for which we find [Fe/H] = -2.30 {+-} 0.15 dex, E(B - V) = 0.09 {+-} 0.02 mag, and (m - M){sub 0} = 20.6 {+-} 0.1 mag, in good agreement with the literature values. We have obtained a V, B - V color-magnitude diagram (CMD) of Hercules that reaches V {approx} 25 mag and extends beyond the galaxy's half-light radius over a total area of 40' Multiplication-Sign 36'. The CMD and the RR Lyrae stars indicate the presence of a population as old and metal-poor as (at least) the Galactic globular cluster M68.

  10. The LYRA Instrument Onboard PROBA2: Description and In-Flight Performance

    NASA Astrophysics Data System (ADS)

    Dominique, M.; Hochedez, J.-F.; Schmutz, W.; Dammasch, I. E.; Shapiro, A. I.; Kretzschmar, M.; Zhukov, A. N.; Gillotay, D.; Stockman, Y.; BenMoussa, A.

    2013-08-01

    The Large Yield Radiometer (LYRA) is an XUV-EUV-MUV (soft X-ray to mid-ultraviolet) solar radiometer onboard the European Space Agency Project for On-Board Autonomy 2 (PROBA2) mission, which was launched in November 2009. LYRA acquires solar-irradiance measurements at a high cadence (nominally 20 Hz) in four broad spectral channels, from soft X-ray to MUV, which have been chosen for their relevance to solar physics, space weather, and aeronomy. We briefly review the design of the instrument, give an overview of the data products distributed through the instrument website, and describe how the data are calibrated. We also briefly present a summary of the main fields of research currently under investigation by the LYRA consortium.

  11. Multicenter evaluation of the Quidel Lyra Direct C. difficile nucleic acid amplification assay.

    PubMed

    Beck, Eric T; Buchan, Blake W; Riebe, Katherine M; Alkins, Brenda R; Pancholi, Preeti; Granato, Paul A; Ledeboer, Nathan A

    2014-06-01

    Clostridium difficile is a Gram-positive bacterium commonly found in health care and long-term-care facilities and is the most common cause of antibiotic-associated diarrhea. Rapid detection of this bacterium can assist physicians in implementing contact precautions and appropriate antibiotic therapy in a timely manner. The purpose of this study was to compare the clinical performance of the Quidel Lyra Direct C. difficile assay (Lyra assay) (Quidel, San Diego, CA) to that of a direct cell culture cytotoxicity neutralization assay (CCNA) and enhanced toxigenic culture. This study was performed at three geographically diverse laboratories within the United States using residual stool specimens submitted for routine C. difficile testing. Residual samples were tested using the Lyra assay on three real-time PCR platforms, and results were compared to those for direct CCNA and enhanced toxigenic culture. The test results for all platforms were consistent across all three test sites. The sensitivity and specificity of the Lyra assay on the SmartCycler II, ABI 7500 Fast DX, and ABI QuantStudio DX instruments compared to CCNA were 90.0% and 93.3%, 95.0% and 94.2%, and 93.8% and 95.0%, respectively. Compared to enhanced toxigenic culture, the sensitivity and specificity of the Lyra assay on the SmartCycler II, ABI 7500, and QuantStudio instruments were 82.1% and 96.9%, 89.3% and 98.8%, and 85.7% and 99.0%, respectively. Overall, the Lyra assay is easy to use and versatile and compares well to C. difficile culture methods. PMID:24671790

  12. Multicenter Evaluation of the Quidel Lyra Direct C. difficile Nucleic Acid Amplification Assay

    PubMed Central

    Beck, Eric T.; Buchan, Blake W.; Riebe, Katherine M.; Alkins, Brenda R.; Pancholi, Preeti; Granato, Paul A.

    2014-01-01

    Clostridium difficile is a Gram-positive bacterium commonly found in health care and long-term-care facilities and is the most common cause of antibiotic-associated diarrhea. Rapid detection of this bacterium can assist physicians in implementing contact precautions and appropriate antibiotic therapy in a timely manner. The purpose of this study was to compare the clinical performance of the Quidel Lyra Direct C. difficile assay (Lyra assay) (Quidel, San Diego, CA) to that of a direct cell culture cytotoxicity neutralization assay (CCNA) and enhanced toxigenic culture. This study was performed at three geographically diverse laboratories within the United States using residual stool specimens submitted for routine C. difficile testing. Residual samples were tested using the Lyra assay on three real-time PCR platforms, and results were compared to those for direct CCNA and enhanced toxigenic culture. The test results for all platforms were consistent across all three test sites. The sensitivity and specificity of the Lyra assay on the SmartCycler II, ABI 7500 Fast DX, and ABI QuantStudio DX instruments compared to CCNA were 90.0% and 93.3%, 95.0% and 94.2%, and 93.8% and 95.0%, respectively. Compared to enhanced toxigenic culture, the sensitivity and specificity of the Lyra assay on the SmartCycler II, ABI 7500, and QuantStudio instruments were 82.1% and 96.9%, 89.3% and 98.8%, and 85.7% and 99.0%, respectively. Overall, the Lyra assay is easy to use and versatile and compares well to C. difficile culture methods. PMID:24671790

  13. Random variations in the ultraviolet spectrum of Beta Lyrae

    NASA Technical Reports Server (NTRS)

    Bless, R. C.; Eaton, J. A.; Meade, M. R.

    1977-01-01

    Spectrophotometric scans of Beta Lyrae over the wavelength range from 1100 to 3700 A are analyzed which were obtained at different times with different resolutions by the OAO 2 satellite and from the ground. A model atmosphere with normal H and He abundances, an electron temperature of 11,000 K, and log g of 3.0 is found to fit the visual region of the spectrum well but to be a poor representation in the Balmer continuum. It is shown that a large complex emission feature dominates the spectrum from about 1700 to 2200 A, that there is a very pronounced strengthening of the spectrum just shortward of the 1550-A C IV feature at phase 0.69, and that the overall level of the spectrum shortward of 1400 A is quite high in comparison with the broad emission feature. A model is discussed in which the light from a disk-shaped secondary is highly concentrated toward the polar regions.

  14. Long-term irradiance observation and short-term flare prediction with LYRA on PROBA2

    NASA Astrophysics Data System (ADS)

    Dammasch, Ingolf; Dominique, Marie; West, Matthew; Katsiyannis, Thanassis; Ryan, Daniel; Wauters, Laurence

    The solar radiometer LYRA on board the ESA micro-satellite PROBA2 has observed the Sun continuously since January 2010 in various spectral band passes, and has gained a considerable data base. Two of the LYRA channels cover the irradiance between soft X-ray and extreme ultraviolet. The variation of the sunspot number appears to show a strong similarity with the variation of these channels, when their long-range development is taken into account. The same holds for SXR levels observed by the GOES satellites. Due to LYRA's bandwidth and coverage of various active-region temperatures, its relatively smooth development may yield some information on the structure of the current solar cycle. On its websites, LYRA presents not only EUV and SXR time series in near real-time, but also information on flare parameters and long-term irradiance and sunspot levels. It will be demonstrated whether it is possible to aid space weather forecast with these statistical data, especially for the prediction of expected flare strength on a daily basis.

  15. In situ detections of Space Weather by the LYRA radiometer on board the PROBA2 satellite

    NASA Astrophysics Data System (ADS)

    Katsiyannis, Athanassios; Kruglanski, Michel; De Donder, Erwin; Dammasch, Ingolf; Dominique, Marie; Ben Moussa, Ali

    The Large Yield RAdiometer (LYRA) is an ultraviolet irradiance radiometer on-board ESA's PROBA2 micro-satellite. Since it's launch in 2009 it observes the Sun in four different passbands, chosen for their relevance to solar physics, aeronomy and space weather. Flying on an altitude of 735km, LYRA proved to be an excellent flare monitor and is involved in the analysis the atmospheric composition of the Earth. One of the most peculiar and intriguing results of LYRA is the detection of short, strong, bursts that do not directly correlate with solar coronal events, nor with pointing of the instrument to Earth's upper atmosphere, but correlate well with high K_{p} index on Earth's surface. As LYRA has the ability to observe in four different UV bandpasses, the comparison between the filters that allow the detection of this activity versus those that do not, reveals very interesting results as to the nature of those detections. This contribution will focus on the investigation and identification of this phenomenon and it will include crucial comparisons to other space-born instruments that do not detect the same effect.

  16. 14. ALABAMA, SUMTER CO., EPES RAILROAD BRIDGE Southern RR at ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    14. ALABAMA, SUMTER CO., EPES RAILROAD BRIDGE Southern RR at Epes Alabama Great Southern RR bridge. View from S. Copy of photo taken in 1922 by Jack Donnell, Columbus, Ms. Sarcone Photography, Columbus, Ms., Sep 1978. - Bridges of the Upper Tombigbee River Valley, Cochrane, Pickens County, AL

  17. 20. BLUEPRINT, RR BRIDGE MISSISSIPPI, CLAY CO., WAVERLY L.% MI. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    20. BLUEPRINT, RR BRIDGE MISSISSIPPI, CLAY CO., WAVERLY L.% MI. S of MS. 50 Proposed bridge, by Phoenis Bridge Co., Phoenixville, Pa. 218-foot turn span, with load bearing. 21 May 1914. Act. size: 16X35 in. Credit: Columbus and Greenville RR, Columbus, Ms. Sarcone Photography, Columbus, Ms. Sept 1978. - Bridges of the Upper Tombigbee River Valley, Columbus, Lowndes County, MS

  18. 18. BLUEPRINT, RR BRIDGE Tombigbee R. MISSISSIPPI, CLAY CO., WAVERLY ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    18. BLUEPRINT, RR BRIDGE Tombigbee R. MISSISSIPPI, CLAY CO., WAVERLY 1.5 mi. S of MS 50 Detail: 'Georgia Pacific Rwy. -- Tombigbee River Bridge Elevation' with river profile, May 16, 1888. Credit: Columbus and Greenville Rr, Columbus, Ms. DWG = S-3-342. Sarcone Photography, Columbus, Ms Sep 1978. - Bridges of the Upper Tombigbee River Valley, Columbus, Lowndes County, MS

  19. Lichtkurve und Periode des RR-Lyrae-Sterns HO Her und GSC 02589-00332, ein W-UMa-Veraenderlicher im Feld

    NASA Astrophysics Data System (ADS)

    Groebel, Rainer

    2015-01-01

    Based on data from the SWASP database and on recent observations 110 maxima and 78 minima timings of the little studied star HO Her could be derived. During the reduction of SWASP data, discrepancies between magnitudes given by series taken simultaneously through different cameras appeared, so that in the present case the reliability of the TAMFLUX correction must be questioned. From the variations in amplitude, a regular secondary cycle could not be derived, but the variations in phase revealed a 17.4 d Blazhko period. Since the discovery, the period remains essentially constant. The ephemeris is improved to HJD (max.) = 2456802.4954(9) + 0.47269795(16) x E One of the comparison stars, GSC 02589-00332 (16:56:31.98 +30:22:22.5) revealed itself as a variable of the W UMa type presenting 0.6 mag. deep total eclipses at primary and 0.5 mag. partial eclipse at secondary minimum. As a variable, it is already known as ROTSE1 J165631.98+302222.0. From SWASP data, 138 minima spreading over 4 years could be derived. The 2014 minima showed positive (O-C) values, indicating a progressive lengthening of the period. The minima timings could be best represented by the quadratic ephemeris HJD (max.) = 2456797.5267 + 0.41111232 x E + 2.625*10 -10 x E^2

  20. VizieR Online Data Catalog: RR Lyrae variables in ESO294-G010 and ESO410-G005 (Yang+, 2014)

    NASA Astrophysics Data System (ADS)

    Yang, S.-C.; Wagner-Kaiser, R.; Sarajedini, A.; Kim, S. C.; Kyeong, J.

    2016-08-01

    The science images of ESO294-G010 and ESO410-G005 used in this study were taken with the Advanced Camera for Surveys Wide Field Channel (ACS/WFC) on board Hubble Space Telescope (HST) as a part of GO-10503 (PI: Da Costa). ESO294-G010 (R.A.=00:26:33.40 (J2000), Decl.=-41:51:19.0 (J2000)) was observed on the HJD (+2453000) range 859.27358-861.13659 with the F606W filter, and on the HJD (+2453000) range 859.40613-861.00342 with the F814W filter. ESO410-G005 (R.A.=00:15:31.40 (J2000), Decl.=-32:10:47.0 (J2000)) was observed on the HJD (+2453000) range 861.40425-863.21702 with the F606W filter, and on the HJD (+2453000) range 861.53711-866.08158 with the filter F814W. The central regions of each galaxy were placed on one of WFC chips so that the imaging covers almost the entire visual extent of the targets. ESO294-G010 was imaged 12 times in the F606W and 24 times in the F814W filter with an exposure time of 1160s during the observing baseline of ~1.86days. The same number of exposures were obtained for the observations of ESO410-G005 with an exposure time of 1120s over the observing baseline of 4.55days. The basic properties of each of these RRL candidates are summarized in Tables 2 and 3. We have also uncovered a significant number of Luminous Variable (LV) candidates in both transition-type dwarf galaxies (22 in ESO294-G010; 19 in ESO410-G005). Their photometric and pulsation properties are summarized in Table4. (4 data files).

  1. 2. Historic American Buildings Survey Southern Pacific RR Coll. About ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    2. Historic American Buildings Survey Southern Pacific RR Coll. About 1869 Oakland Point Pier - Used by First Central Pacific Train to Enter Oakland -- November 8, 1869 - Southern Pacific Mole & Pier, Seventh Street, Oakland, Alameda County, CA

  2. The Complex QT/RR Relationship in Mice

    PubMed Central

    Roussel, Julien; Champeroux, Pascal; Roy, Jérôme; Richard, Sylvain; Fauconnier, Jérémy; Le Guennec, Jean-Yves; Thireau, Jérôme

    2016-01-01

    The QT interval reflects the time between the depolarization of ventricles until their repolarization and is usually used as a predictive marker for the occurrence of arrhythmias. This parameter varies with the heart rate, expressed as the RR interval (time between two successive ventricular depolarizations). To calculate the QT independently of the RR, correction formulae are currently used. In mice, the QT-RR relationship as such has never been studied in conscious animals, and correction formulas are mainly empirical. In the present paper we studied how QT varies when the RR changes physiologically (comparison of nocturnal and diurnal periods) or after dosing mice with tachycardic agents (norepinephrine or nitroprusside). Our results show that there is significant variability of QT and RR in a given condition, resulting in the need to average at least 200 consecutive complexes to accurately compare the QT. Even following this method, no obvious shortening of the QT was observed with increased heart rate, regardless of whether or not this change occurs abruptly. In conclusion, the relationship between QT and RR in mice is weak, which renders the use of correction formulae inappropriate and misleading in this species. PMID:27138175

  3. A redetermination of the luminosity, distance, and reddening of Beta Lyrae

    NASA Technical Reports Server (NTRS)

    Dobias, J. J.; Plavec, M. J.

    1985-01-01

    The most likely distance to the Beta Lyrae system is redetermined to lie at 370 pc, corresponding to a distance modulus of 7.8 mag, while the correct modulus value probably lies in the 7.7-8.0 mag range, corresponding to a distance range between 345 and 400 pc. On the basis of Wilson's (1974) model, the phase-averaged absolute visual magnitude of the primary component is -4.1 mag; this star is therefore a very luminous giant, classifiable as B8.5 or B9, with a luminosity class of II-Ib. The present data are based on optical and IUE scans of the brightest visual companion to Beta Lyrae, HD 174664, together with an analysis of the H line profiles in its spectrum.

  4. 2D and 3D Mass Transfer Simulations in β Lyrae System

    NASA Astrophysics Data System (ADS)

    Nazarenko, V. V.; Glazunova, L. V.; Karetnikov, V. G.

    2001-12-01

    2D and 3D mass transfer simulations of the mass transfer in β Lyrae binary system. We have received that from a point L3 40 per cent of mass transfer from L1-point is lost.The structure of a gas envelope, around system is calculated.3-D mass transfer simulations has shown presence the spiral shock in the disk around primary star's and a jet-like structures (a mass flow in vertical direction) over a stream.

  5. LYRA and SWAP, the two Solar Instruments on-board PROBA2

    NASA Astrophysics Data System (ADS)

    Dominique, M.; Berghmans, D.; Schmutz, W. K.; Dammasch, I.; De Groof, A.; Halain, J.; Hochedez, J.; Kretzschmar, M.; Seaton, D. B.

    2011-12-01

    PROBA2 (http://proba2.sidc.be) is an ESA micro-satellite that was launched in November 2009. Two instruments on-board, SWAP and LYRA, are devoted to solar observations. SWAP (PI: D. Berghmans) is an EUV imager observing the corona with a bandpass centered on 174 Å at a cadence of 1-2 min. Its high contrast images, large FOV and flexible off-pointing capabilities make SWAP particularly well suited for the study of coronal eruptions. LYRA (PI: M. Dominique) is a UV-EUV radiometer observing in four spectral channels, chosen for their relevance in solar physics and aeronomy. Its very fast acquisition cadence (up to 100 Hz) allows scientists to perform detailed analysis of solar flares. We discuss the characteristics of both instruments, review their performance and evolution, and highlight their complementarity to other missions. We also present the data products that can be downloaded from the mission website and give an overview of the various investigations for which SWAP and LYRA data are currently used (CMEs, flares, solar variability, and many others).

  6. Light-induced COP9 signalosome expression in the Indian false vampire bat Megaderma lyra.

    PubMed

    Rajan, K Emmanuvel; Rajkumar, R; Liao, Chen-Chug; Ganesh, A; Marimuthu, G

    2010-01-01

    The COP9 signalosome (CSN) is a multi-subunit protein complex conserved in plants and animals. CSN subunits have been identified as light-mediated master regulators of eukaryotic circadian clocks from fungi to animals. The Indian false vampire bat Megaderma lyra is completely adapted to an anthropic biotope and behavioral studies have reported that M. lyra exhibits light-sampling behavior to assess environmental light. LC-MS-MS results for a 36 kDa protein were analyzed using the Sequest search engine, and COP9 signalosome subunit 5 (CSN5) was pinpointed as having the highest score with 6 matching peptides. To confirm the presence of CSN5, up-regulated cDNA was amplified, sequenced, and identified as CSN5. Furthermore, semi-quantitative RT-PCR analysis demonstrated that the level of induction of CSN5 was regulated by environmental light. We estimated the level of expression across a light-dark cycle and observed a higher level of expression at the end of the light phase. Similarly, when the animal was shifted from continuous dark to light, CSN5 expression was induced. Correspondingly, we detected the similar pattern of translated protein with JAB1 antibody. Knowledge about the circadian rhythm and its molecular mechanism in Chiroptera is very limited and this study suggests that CSN5 might be involved in the M. lyra light-signaling process. PMID:19787423

  7. Solar Spectral Irradiance as observed by LYRA/PROBA2 and PREMOS/PICARD

    NASA Astrophysics Data System (ADS)

    Cessateur, G.; Shapiro, A. I.; Dominique, M.; Kretzschmar, M.; Krivova, N.; Shapiro, A. V.; Schmutz, W.; Schoell, M.; Solanki, S.; Tagirov, R.; Thuillier, G.; Wehrli, C.; Yeo, K. L.

    2012-04-01

    Total and Spectral Solar Irradiance are key input parameters to atmospheric/oceanic and space weather models. Both vary on time-scales ranging from days to millennia, although a complete picture of the solar irradiance variability is still missing. The recent launch of two European missions PROBA-2 with LYRA radiometer onboard and PICARD with PREMOS package onboard provides therefore valuable information and nourishes theoretical models. Both instruments covers the solar spectrum from the EUV to near-infrared. Here we present spectral solar irradiance data from these two recent missions. After a proper correction of the degradation and non-solar signatures, we compare these data with those from the VIRGO/SOHO and SOLSTICE+SIM/SORCE experiments. Both LYRA and PREMOS have also observed several solar eclipses, which allows us to accurately retrieve the center-to-limb variations (CLVs) of the quiet Sun's brightness at the wavelengths of the corresponding channels. CLVs play indeed an important role in modelling of the solar irradiance variability. We show that calculations with the published COde for Solar Irradiance (COSI) yield CLVs that are in good agreement with measurements. Finally we use COSI to model the variability of the irradiance, assuming that the latter is determined by the evolution of the solar surface magnetic field as seen with SDO/HMI data. These theoretical results are compared to PREMOS and LYRA measurements.

  8. Variable stars in the globular cluster M 28 (NGC 6626)

    NASA Astrophysics Data System (ADS)

    Prieto, G.; Catelan, M.; Contreras Ramos, R.; Pritzl, B. J.; Smith, H. A.; Alonso-García, J.

    2012-07-01

    Context. We present a new search for variable stars in the Galactic globular cluster M 28 (NGC 6626). Aims: The search is based on a series of BVI images obtained with the SMARTS Consortium's 1.3 m telescope at Cerro Tololo Inter-American Observatory, Chile. Methods: The search was carried out using the ISIS v2.2 image subtraction package. Results: We find a total of 25 variable stars in the field of the cluster, nine being new discoveries. Of the newly found variables, one is an ab-type RR Lyrae star, six are c-type RR Lyrae, and two are long-period/semi-regular variables. V22, previously classified as a type II Cepheid, appears as a bona-fide RRc in our data. In turn, V20, previously classified as an ab-type RR Lyrae, could not be properly phased with any reasonable period. Conclusions: The properties of the ab-type RR Lyrae stars in M 28 appear most consistent with an Oosterhoff-intermediate classification, which is unusual for bona-fide Galactic globulars clusters. However, the cluster's c-type variables do not clearly support such an Oosterhoff type, and a hybrid Oosterhoff I/II system is accordingly another possibility, thus raising the intriguing possibility of multiple populations being present in M 28. Coordinates, periods, and light curves in differential fluxes are provided for all the detected variables. Based on observations obtained with the SMARTS Consortium 1.3 m telescope at the Cerro Tololo Inter-American Observatory, Chile.Figures 2-5 are available in electronic form at http://www.aanda.org

  9. Effects of RR segment duration on HRV spectrum estimation.

    PubMed

    Singh, Dilbag; Vinod, Kumar; Saxena, Suresh C; Deepak, Kishore K

    2004-06-01

    Although patterns of heart rate variability (HRV) hold considerable promise for clarifying issues in clinical applications, the inappropriate quantification and interpretation of these patterns may obscure critical issues or relationships and may impede rather than foster the development of clinical applications. The duration of the RR interval series is not a matter of convenience but a fine balance between two important issues: acceptable variance and stationarity of the time series on one hand, and acceptable resolution of the spectral estimate and reduced spectral leakage on the other. Further, in the standard short-term HRV analysis, it has been observed that the previous studies in HRV spectral analysis use a wide range of RR interval segment duration for spectral estimation by Welch's algorithm. The standardization of RR interval segment duration is also important for comparisons among studies and is essential for within-study experimental contrasts. In the present study, a comparative analysis for RR interval segment durations has been made to propose an optimal RR interval segment duration. Firstly a simulated signal was analyzed with Hann window and zero padding for the segment lengths of 1024, 512, 256 and 128 samples resampled at 4 Hz with 50% overlapping. Again, the above procedure was applied to RR interval series and it was concluded that segment length of 256 samples with 50% overlapping provides a smoothed spectral estimate with clearly outlined peaks in low- and high-frequency bands. This easily understandable and interpretable spectral estimate leads to a better visual and automated analysis, which is not only desirable in basic physiology studies, but also a prerequisite for a widespread utilization of frequency domain techniques in clinical studies, where simplicity and effectiveness of information are of primary importance. PMID:15253123

  10. 21. Providence & Worchester RR: Freight house. Providence, Providence Co., ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    21. Providence & Worchester RR: Freight house. Providence, Providence Co., RI. Sec. 4119, mp 185.66 (See HAER no. RI-3 for further documentation on this site.) - Northeast Railroad Corridor, Amtrak route between CT & MA state lines, Providence, Providence County, RI

  11. 86. New York, New Haven & Hartford RR: East New ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    86. New York, New Haven & Hartford RR: East New Haven Shops Roundhouse. East New Haven, New Haven Co., CT. (Not on NEC). - Northeast Railroad Corridor, Amtrak Route between New York/Connecticut & Connecticut/Rhode Island State Lines, New Haven, New Haven County, CT

  12. 84. New York, New Haven & Hartford RR: East New ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    84. New York, New Haven & Hartford RR: East New Haven Shops & Yards. East New Haven, New Haven Co., CT. (Not on NEC). - Northeast Railroad Corridor, Amtrak Route between New York/Connecticut & Connecticut/Rhode Island State Lines, New Haven, New Haven County, CT

  13. 88. New York, New Haven & Hartford RR: East New ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    88. New York, New Haven & Hartford RR: East New Haven Shops Roundhouse. East New Haven, New Haven Co., CT. (Not on NEC). - Northeast Railroad Corridor, Amtrak Route between New York/Connecticut & Connecticut/Rhode Island State Lines, New Haven, New Haven County, CT

  14. 83. New York, New Haven & Hartford RR: East New ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    83. New York, New Haven & Hartford RR: East New Haven Shops & Yards. East New Haven, New Haven Co., CT. (Not on NEC). - Northeast Railroad Corridor, Amtrak Route between New York/Connecticut & Connecticut/Rhode Island State Lines, New Haven, New Haven County, CT

  15. 85. New York, New Haven & Hartford RR: East New ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    85. New York, New Haven & Hartford RR: East New Haven Shops Roundhouse. East New Haven, New Haven Co., CT. (Not on NEC). - Northeast Railroad Corridor, Amtrak Route between New York/Connecticut & Connecticut/Rhode Island State Lines, New Haven, New Haven County, CT

  16. 61. New York, New Haven & Hartford RR: New Haven ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    61. New York, New Haven & Hartford RR: New Haven Station. New Haven, New Haven Co., CT. Sec. 9108, MP 72.00. - Northeast Railroad Corridor, Amtrak Route between New York/Connecticut & Connecticut/Rhode Island State Lines, New Haven, New Haven County, CT

  17. 80. New York, New Haven & Hartford RR: East New ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    80. New York, New Haven & Hartford RR: East New Haven Shops & Yards. East New Haven, New Haven Co., CT. (Not on NEC). - Northeast Railroad Corridor, Amtrak Route between New York/Connecticut & Connecticut/Rhode Island State Lines, New Haven, New Haven County, CT

  18. 87. New York, New Haven & Hartford RR: East New ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    87. New York, New Haven & Hartford RR: East New Haven Shops Roundhouse. East New Haven, New Haven Co., CT. (Not on NEC). - Northeast Railroad Corridor, Amtrak Route between New York/Connecticut & Connecticut/Rhode Island State Lines, New Haven, New Haven County, CT

  19. 79. New York, New Haven & Hartford RR: East New ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    79. New York, New Haven & Hartford RR: East New Haven Shops with Roundhouse in foreground. East New Haven, New Haven Co., CT. (Not on NEC). - Northeast Railroad Corridor, Amtrak Route between New York/Connecticut & Connecticut/Rhode Island State Lines, New Haven, New Haven County, CT

  20. 82. New York, New Haven & Hartford RR: East New ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    82. New York, New Haven & Hartford RR: East New Haven Shops & Yards. East New Haven, New Haven Co., CT. (Not on NEC). - Northeast Railroad Corridor, Amtrak Route between New York/Connecticut & Connecticut/Rhode Island State Lines, New Haven, New Haven County, CT

  1. 81. New York, New Haven & Hartford RR: East New ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    81. New York, New Haven & Hartford RR: East New Haven Shops & Yards. East New Haven, New Haven Co., CT. (Not on NEC). - Northeast Railroad Corridor, Amtrak Route between New York/Connecticut & Connecticut/Rhode Island State Lines, New Haven, New Haven County, CT

  2. 10. New York Connecting RR viaduct approaching Hell Gate Bridge ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    10. New York Connecting RR viaduct approaching Hell Gate Bridge from S. Queens, Queens Co., NY. Sec. 4207, MP 7.29. - Northeast Railroad Corridor, Amtrak Route between New Jersey/New York & New York/Connecticut State Lines, New York County, NY

  3. 13. New York Connecting RR: Hell Gate Bridge. Queens, Queens ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    13. New York Connecting RR: Hell Gate Bridge. Queens, Queens Co., NY. Sec. 4207, MP 7.29. (See HAER No. NY-88 for further documentation on this site). - Northeast Railroad Corridor, Amtrak Route between New Jersey/New York & New York/Connecticut State Lines, New York County, NY

  4. 11. New York Connecting RR: Hell Gate Bridge. Queens, Queens ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    11. New York Connecting RR: Hell Gate Bridge. Queens, Queens Co., NY. Sec. 4207, MP 7.29. (See HAER No. NY-88 for further documentation on this site). - Northeast Railroad Corridor, Amtrak Route between New Jersey/New York & New York/Connecticut State Lines, New York County, NY

  5. 12. New York Connecting RR: Hell Gate Bridge. Queens, Queens ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    12. New York Connecting RR: Hell Gate Bridge. Queens, Queens Co., NY. Sec. 4207, MP 7.29. (See HAER No. NY-88 for further documentation on this site). - Northeast Railroad Corridor, Amtrak Route between New Jersey/New York & New York/Connecticut State Lines, New York County, NY

  6. IUE and optical observations of MV Lyrae at intermediate and low states

    NASA Technical Reports Server (NTRS)

    Szkody, P.; Downes, R. A.

    1982-01-01

    Ultraviolet observations of MV Lyrae were obtained with the aid of the International Ultraviolet Explorer (IUE) spacecraft on 1979 December 2 when MV Lyr was at a normal low state and on 1980 December 8. The optical observations were obtained at Kitt Peak, Lick Observatory, and the University of Washington Observatory with various image-tube scanners and photometers. The photometric colors were found to be very blue at the very low state and at the normal low state. Robinson et al. (1981) have identified three components in their very low-state optical spectra. The significance of the observations is discussed.

  7. The BUSS spectrum of Beta Lyrae. [Balloon-borne Ultraviolet Stellar Spectrograph

    NASA Technical Reports Server (NTRS)

    Hack, M.; Sahade, J.; De Jager, C.; Kondo, Y.

    1983-01-01

    The spectrum of Beta Lyrae from about 1975 to 3010 A taken with the Balloon-borne ultraviolet Stellar Spectrograph experiment in May 1976 at phase 0.61 P is analyzed. Results show the presence of N II semi-forbidden emission and provide evidence for about the same location, in the outer envelope of the system, of the layers responsible for the resonance Mg II doublet emissions and for the "narrow" H-alpha emission. In addition, three sets of absorption lines, P Cygni profiles of Fe III and broad Beals Type III emissions of Mg II, are found to be present.

  8. Evaluation of the Lyra Direct Strep Assay To Detect Group A Streptococcus and Group C and G Beta-Hemolytic Streptococcus from Pharyngeal Specimens

    PubMed Central

    Darnell, Elizabeth M.; Prada, Anne E.; Hansz, Dana M.; Robinson-Dunn, Barbara

    2015-01-01

    The Lyra Direct strep assay was compared to culture for its ability to detect Streptococcus group A and β-hemolytic groups C/G using rapid antigen-negative pharyngeal specimens (n = 161). The Lyra assay correctly detected all β-hemolytic streptococci (group A, n = 19; group C/G, n = 5). In batch mode, the Lyra assay reduced intralaboratory turnaround time by 60% (18.1 h versus 45.0 h) but increased hands-on time by 96% (3 min 16 s versus 1 min 40 s per specimen). PMID:26491174

  9. "Lyra" Space Stellar Survey and Establishing a Large Grid of Photometric Standards

    NASA Astrophysics Data System (ADS)

    Mironov, A.; Zakharov, A.; Prokhorov, M.

    2016-05-01

    The "Lyra" space experiment is currently being prepared in Russia. Its main goal is to perform high precision 10-color photometry for all V<16 mag stars. Observations will be made using a 500-mm diameter 3-m focal length Ritchey-Chretien telescope with an afocal lens corrector mounted on the Russian segment of the International Space Station (ISS) and equipped with CCDs operated in the time delay and integration (drift, TDI) mode. One of the most important tasks of the "Lyra" mission is to create a dense all-sky grid of high-precision photometric standards. The total number of standards should be on the order of several million, and to achieve this goal, more than 300 million stars will be measured in the course of the mission. The photometric system must include standards in all ranges of magnitudes from the brightest stars down to 16th magnitude. Small random error will be achieved by providing sufficiently strong signal in all passbands and using highly accurate and stable detecting equipment. The random error of measured magnitudes is expected to be 0m.001–0m.003 and about 0m.01 for stars brighter than 14th magnitude and fainter stars, respectively. The system must be free from systematic errors, which are to be minimized by careful ground -based calibration and by maintaining this calibration throughout the mission.

  10. Proba2/Lyra: six years of EUV solar irradiance observation, from short to long timescales

    NASA Astrophysics Data System (ADS)

    Dominique, Marie; Dammasch, Ingolf; Wauters, Laurence; Katsiyannis, Athanassios

    2016-07-01

    With important questions such as the climate changes and the role of the Sun debated by the scientific community, it appears crucial to measure the evolution of the solar spectral irradiance. This is especially the case in the soft X-ray to UV range, which shows the highest variability and impacts the Earth's ionosphere on both long (background emission evolution) and short (e.g. flares) timescales. LYRA, the Large Yield Radiometer on-board PROBA2 has been observing the Sun for more than six years, making observations in four broadband channels in the EUV-to-MUV range, accumulating quasi-uninterrupted time series. However, maintaining instruments capable of high-quality measurements over years in the harsh space environment is an every-day challenge. We will provide an up-to-date overview of the instrument state and of its data products. We will then present how the LYRA data have been used to analyze the solar impact on the Earth upper atmosphere, addressing successively the effects on the long and short timescales.

  11. Ultraviolet light curves of beta Lyrae: Comparison of OAO A-2, IUE, and Voyager Observations

    NASA Technical Reports Server (NTRS)

    Kondo, Yoji; Mccluskey, George E.; Silvis, Jeffery M. S.; Polidan, Ronald S.; Mccluskey, Carolina P. S.; Eaton, Joel A.

    1994-01-01

    The six-band ultraviolet light curves of beta Lyrae obtained with the Orbiting Astronomical Observatory (OAO) A-2 in 1970 exhibited a very unusual behavior. The secondary minimum deepened at shorter wavelength, indicating that one was not observing light variations caused primarily by the eclipses of two stars having a roughly Planckian energy distribution. It was then suggested that the light variations were caused by a viewing angle effect of an optically thick, ellipsoidal circumbinary gas cloud. Since 1978 beta Lyrae has been observed with the International Ultraviolet Explorer (IUE) satellite. We have constructed ultraviolet light curves from the IUE archival data for comparison with the OAO A-2 results. We find that they are in substantial agreement with each other. The Voyager ultraviolet spectrometer was also used to observe this binary during a period covered by IUE observations. The Voyager results agree with those of the two other satellite observatories at wavelengths longer than about 1350 A. However, in the wavelength region shorter than the Lyman-alpha line at 1216 A, the light curves at 1085 and 965 A show virtually no light variation except an apparent flaring near phase 0.7, which is also in evidence at longer wavelengths. We suggest that the optically thick circumbinary gas cloud, which envelops the two stars completely, assumes a roughly spherical shape when observed at these shorter wavelengths.

  12. Analysis of the IUE spectra of the strongly interacting binary beta Lyrae

    NASA Technical Reports Server (NTRS)

    Mccluskey, George E., Jr.

    1993-01-01

    The six-band ultraviolet light curves of beta Lyrae obtained with the Orbiting Astronomical Observatory A-2 in 1970 exhibited a very unusual behavior. The secondary minimum deepened at shorter wavelength, indicating that one was not observing light variations caused primarily by the eclipses of two stars having a roughly Planckian energy distribution. It was then suggested that the light variations were caused by a viewing angle effect of an optically-thick, ellipsoidal circumbinary gas cloud. Since 1978 beta Lyrae has been observed with the International Ultraviolet Explorer (IUE) satellite. We have constructed ultraviolet light curves from the IUE archival data for comparison with the OAO-A2 results. We find that they are in substantial agreement with each other. The Voyager ultraviolet spectrometer was also used to observe this binary during a period covered by IUE observations. The Voyager results agree with those of the two other satellite observatories at wavelengths longer than about 1350 A. However, in the wavelength region shorter than the Lyman-alpha line at 1216 A, the light curves at 1085 A and 965 A show virtually no light variation except an apparent flaring near phase 0.7, which is also in evidence at longer wavelengths. We suggest that the optically-thick circumbinary gas cloud, which envelops the two stars completely, assumes a roughly spherical shape when observed at these shorter wavelengths.

  13. 50 CFR 680.5 - Recordkeeping and reporting (R&R).

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 50 Wildlife and Fisheries 13 2013-10-01 2013-10-01 false Recordkeeping and reporting (R&R). 680.5... General § 680.5 Recordkeeping and reporting (R&R). (a) General requirements—(1) Recording and reporting... participants in the CR fisheries are responsible for complying with the following R&R...

  14. ECG R-R peak detection on mobile phones.

    PubMed

    Sufi, F; Fang, Q; Cosic, I

    2007-01-01

    Mobile phones have become an integral part of modern life. Due to the ever increasing processing power, mobile phones are rapidly expanding its arena from a sole device of telecommunication to organizer, calculator, gaming device, web browser, music player, audio/video recording device, navigator etc. The processing power of modern mobile phones has been utilized by many innovative purposes. In this paper, we are proposing the utilization of mobile phones for monitoring and analysis of biosignal. The computation performed inside the mobile phone's processor will now be exploited for healthcare delivery. We performed literature review on RR interval detection from ECG and selected few PC based algorithms. Then, three of those existing RR interval detection algorithms were programmed on Java platform. Performance monitoring and comparison studies were carried out on three different mobile devices to determine their application on a realtime telemonitoring scenario. PMID:18002800

  15. An Improved Optical Spectral Line List for RR Telescopii

    NASA Technical Reports Server (NTRS)

    Crawford, F. L.; McKenna, F. C.; Keenan, F. P.; Allen, L. H.; Feibelman, W. A.; Ryan, S. G.

    1999-01-01

    The symbiotic nova RR Telescopli has been observed with the 3.9m telescope of the Anglo-Australian Observatory (AAO), using the University College London Echelle Spectrograph in conjunction with a Tek CCD. It displays a rich emission line spectrum, ranging in excitation from N I to [Ni VIII]. We present a list of 824 measured lines, with their suggested identifications and absolute line intensities, covering a wavelength range from 3180 A to 9455 A. The absolute line intensities have been derived by comparing the high resolution data with a flux-calibrated low resolution spectrum taken with the Australian National University 2.3 m telescope. All of the lines have been successfully identified. Comparing our results with those of previous studies indicates that the RR Tel system is advancing towards higher degrees of ionization.

  16. Stellar Archeology in the Galactic Halo with Ultra-faint Dwarfs. VII. Hercules

    NASA Astrophysics Data System (ADS)

    Musella, Ilaria; Ripepi, Vincenzo; Marconi, Marcella; Clementini, Gisella; Dall'Ora, Massimo; Scowcroft, Victoria; Moretti, Maria Ida; Di Fabrizio, Luca; Greco, Claudia; Coppola, Giuseppina; Bersier, David; Catelan, Márcio; Grado, Aniello; Limatola, Luca; Smith, Horace A.; Kinemuchi, Karen

    2012-09-01

    We present the first time-series study of the ultra-faint dwarf galaxy Hercules. Using a variety of telescope/instrument facilities we secured about 50 V and 80 B epochs. These data allowed us to detect and characterize 10 pulsating variable stars in Hercules. Our final sample includes six fundamental-mode (ab-type) and three first-overtone (c-type) RR Lyrae stars, and one Anomalous Cepheid. The average period of the ab-type RR Lyrae stars, langP abrang = 0.68 days (σ = 0.03 days), places Hercules in the Oosterhoff II group, as found for almost the totality of the ultra-faint dwarf galaxies investigated so far for variability. The RR Lyrae stars were used to obtain independent estimates of the metallicity, reddening, and distance to Hercules, for which we find [Fe/H] = -2.30 ± 0.15 dex, E(B - V) = 0.09 ± 0.02 mag, and (m - M)0 = 20.6 ± 0.1 mag, in good agreement with the literature values. We have obtained a V, B - V color-magnitude diagram (CMD) of Hercules that reaches V ~ 25 mag and extends beyond the galaxy's half-light radius over a total area of 40' × 36'. The CMD and the RR Lyrae stars indicate the presence of a population as old and metal-poor as (at least) the Galactic globular cluster M68. Based on data collected at the 2.5 m Isaac Newton Telescope, La Palma, Canary Islands, Spain, at the 4.2 m William Herschel Telescope, Roche de los Muchachos, Canary Islands, Spain, at the 2.2 m ESO/MPI telescope, La Silla, Chile, Proposal 079.D-0587, at the 2 m Liverpool Telescope, Roche de los Muchachos, Canary Islands, Spain, and at the 2 m Faulkes Telescope North, Haleakala Observatory, Hawaii, USA.

  17. Invariant Solutions of Inhomogeneous Universe with Electromagnetic Field in Lyra Geometry

    NASA Astrophysics Data System (ADS)

    Ali, Ahmad T.; Rahaman, F.; Mallick, A.

    2014-12-01

    The present study deals with the cylindrically symmetric inhomogeneous cosmological models for perfect fluid distribution with electro-magnetic field in Lyra geometry. Lie group analysis has been used to identify the generators (symmetries) that leave the given system of partial differential equations (field equations) invariant. With the help of canonical variables associated with these generators, the assigned system of partial differential equations is reduced to an ordinary differential equations whose simple solutions provide nontrivial solutions of the original system. They obtained a new class of invariant (similarity) solutions by considering the potentials of metric and displacement field are functions of coordinates t and x. The physical behavior of the derived models are also discussed.

  18. A study of the P-Cygni lines in the ultraviolet spectrum of Beta Lyrae

    NASA Technical Reports Server (NTRS)

    Mazzali, Paolo A.

    1986-01-01

    The properties of the mass loss from the nondegenerate interacting binary system of beta Lyrae are investigated by analyzing the P-Cygni line profiles in the UV spectrum and considering these to be emitted in the wind outflow from the B8II primary component. Observed UV lines obtained by IUE are compared with theoretical models obtained using Sobolev's approximation. The models give satisfactory fittings. Simultaneous fitting of the resonance lines of Al II (1670 A) and Al III (1863 A) show that if the lines are emitted in the same region of the outflowing shell, as the line widths indicate, the electron temperature in the region is 23,500 K, and the mass loss is 2 times 10 to the minus 7th power solar masses/yr.

  19. The Multicolor Lyra Photometric System for Variable Stars and Halo Studies

    NASA Astrophysics Data System (ADS)

    Mironov, Alexey V.; Zakharov, Andrey I.; Prokhorov, Mikhail E.; Nikolaev, Fedor N.; Tuchin, Maxim N.

    2010-02-01

    The space photometric project ``Lyra" is being developed now in Russia. The project purpose is determination of photometric information and coordinates of natural and artificial space objects, from the brightest ones to 16^{m} in visual light. It is supposed to obtain data for about 40-400 million objects from board of the International Space Station, using an astronomical telescope with a diameter of the main mirror of 0.5 m. The observations will be carried out in a scanning mode. Photometry will be obtained in 10 spectral bands. The expected uncertainty for objects of 16^{m} in the V band is 0.01m. The scanning law is that each object will be observed, on average, one hundred times. The Sternberg Astronomical Institute of the Moscow University is the director of experiment and the head scientific organization. The launch of the apparatus into the orbit is planned for 2013. The central wavelengths of the 10 bands of the Lyra photometric system will be at 195, 218, 270, 350, 440, 550, 700, 825, 930 and 1000 nm. It is shown that combinations of various color indices will allow us to determine confidently both effective temperature and metallicity of stars. The presence of a 218-nm band allows to determine confidently interstellar extinction for stars of O-F spectral types. The photometric system will make it possible to separate halo stars from disk stars and to derive physical parameters of their atmospheres. The main results of the experiment should be: i) a spatial model of the Galaxy at distances to 3 kpc from the Sun; ii) specification of physical parameters of stars and models of stellar evolution; iii) discovering a huge number (millions) of variable stars and determining their variability parameters.

  20. Extreme ultraviolet solar irradiance during the rising phase of solar cycle 24 observed by PROBA2/LYRA

    NASA Astrophysics Data System (ADS)

    Kretzschmar, Matthieu; Dammasch, Ingolf E.; Dominique, Marie; Zender, Joe; Cessateur, Gaël; D'Huys, Elke

    2012-08-01

    The Large-Yield Radiometer (LYRA) is a radiometer that has monitored the solar irradiance at high cadence and in four pass bands since January 2010. Both the instrument and its spacecraft, PROBA2 (Project for OnBoard Autonomy), have several innovative features for space instrumentation, which makes the data reduction necessary to retrieve the long-term variations of solar irradiance more complex than for a fully optimized solar physics mission. In this paper, we describe how we compute the long-term time series of the two extreme ultraviolet irradiance channels of LYRA and compare the results with those of SDO/EVE. We find that the solar EUV irradiance has increased by a factor of 2 since the last solar minimum (between solar cycles 23 and 24), which agrees reasonably well with the EVE observations.

  1. Solar EUV irradiance during solar cycle 24 as observed by PROBA2/LYRA and SDO/EVE

    NASA Astrophysics Data System (ADS)

    Kretzschmar, Matthieu; Dominique, Marie; Dammasch, Ingolf

    2013-04-01

    Solar EUV irradiance affects the upper atmospheres of planets and is a fundamental parameters for space weather. The Large-Yield Radiometer (LYRA) is a radiometer that has monitored the solar irradiance at high cadence and in four pass bands since January 2010. Both the instrument and its spacecraft, PROBA2 (Project for OnBoard Autonomy), have several innovative features for space instrumentation, which makes the data reduction necessary to retrieve the long-term variations of solar irradiance more complex than for a fully optimized solar physics mission. In this presentation, we describe how we compute the long-term time series of the two extreme ultraviolet irradiance channels of LYRA and compare the results with those of SDO/EVE and several proxies.

  2. Evidence for a temperature rise in the outer layers of alpha Lyrae, from Copernicus observations of Lyman-alpha

    NASA Technical Reports Server (NTRS)

    Praderie, F.; Simonneau, E.; Snow, T. P., Jr.

    1975-01-01

    Copernicus satellite observations of the Ly-alpha profiles in alpha Lyrae (Vega) are used to determine whether classical radiative-equilibrium LTE model atmospheres can fit the thermal structure in the outer layers of that star. Two plane-parallel LTE model photospheres of alpha Lyrae are considered: a line-blanketed radiative-equilibrium model with an effective temperature of 9650 K and log g of 4.05, and the same model with a temperature of 9500 K and log g of 4.0. The profiles of the Ly-alpha wings are computed, and it is found that classical LTE models are unable to predict either the observed violet wing or the red wing longwards of 1239 A, regardless of the line source function. It is concluded that the electron temperature must increase outwards over the surface value reached in radiative equilibrium.

  3. Epsilon Lyrae

    NASA Astrophysics Data System (ADS)

    Murdin, P.

    2000-11-01

    Though not very bright, this is a favorite test object for powerful binoculars and small telescopes. Situated 1.6° north-east of Vega, it is known as `the Double Double'. The star can just be seen to be double with the unaided eye, under good conditions by observers with acute eyesight. With binoculars it is easily separated, the component stars being 3.5' apart at a position angle of 173°. It is...

  4. Ventricular Cycle Length Characteristics Estimative of Prolonged RR Interval during Atrial Fibrillation

    PubMed Central

    CIACCIO, EDWARD J.; BIVIANO, ANGELO B.; GAMBHIR, ALOK; EINSTEIN, ANDREW J.; GARAN, HASAN

    2014-01-01

    Background When atrial fibrillation (AF) is incessant, imaging during a prolonged ventricular RR interval may improve image quality. It was hypothesized that long RR intervals could be predicted from preceding RR values. Methods From the PhysioNet database, electrocardiogram RR intervals were obtained from 74 persistent AF patients. An RR interval lengthened by at least 250 ms beyond the immediately preceding RR interval (termed T0 and T1, respectively) was considered prolonged. A two-parameter scatterplot was used to predict the occurrence of a prolonged interval T0. The scatterplot parameters were: (1) RR variability (RRv) estimated as the average second derivative from 10 previous pairs of RR differences, T13–T2, and (2) Tm–T1, the difference between Tm, the mean from T13 to T2, and T1. For each patient, scatterplots were constructed using preliminary data from the first hour. The ranges of parameters 1 and 2 were adjusted to maximize the proportion of prolonged RR intervals within range. These constraints were used for prediction of prolonged RR in test data collected during the second hour. Results The mean prolonged event was 1.0 seconds in duration. Actual prolonged events were identified with a mean positive predictive value (PPV) of 80% in the test set. PPV was >80% in 36 of 74 patients. An average of 10.8 prolonged RR intervals per 60 minutes was correctly identified. Conclusions A method was developed to predict prolonged RR intervals using two parameters and prior statistical sampling for each patient. This or similar methodology may help improve cardiac imaging in many longstanding persistent AF patients. PMID:23998759

  5. RR Tel: Getting Under the Flux Limit: An Observation with FUSE

    NASA Technical Reports Server (NTRS)

    Sonnenborn, George (Technical Monitor); Kenyon, Scott J.

    2004-01-01

    The goal of this program is to acquire a FUSE spectrum of the symbiotic binary RR Tel. With these data, we plan to derive improved constraints on the hot component, the nebula, and perhaps the red giant wind. Based on results from AG Dra, we should also be able to use some line detections to improve atomic parameters for high ionization emission lines. This results would benefit the general FUSE community. As of this writing, the FUSE observation of RR Tel has not been made. Because RR Tel is a very bright UV source, the FUSE team is assessing the likelihood that RR Tel will have an adverse affect on the instrument.

  6. Modeling of the Solar Spectral Irradiance as observed by LYRA/PROBA2 and PREMOS/PICARD

    NASA Astrophysics Data System (ADS)

    Shapiro, A.; Cessateur, G.; Dominique, M.; Krivova, N. A.; Lachat, D.; Rozanov, E.; Schmutz, W. K.; Shapiro, A. V.; Tagirov, R. V.; Thuillier, G. O.; Wehrli, C.

    2011-12-01

    Measurements and modeling of the solar irradiance have gained an increased attention during the last few decades. Nevertheless a complete picture of the solar variability is still missing. Therefore a launch of every new space mission devoted to the measurements of the spectral solar irradiance provides a crucial piece of complementary information and nourishes the theoretical models. We present here spectral solar irradiance data from the recent European missions PROBA-2 (launched on November 2, 2009) and PICARD (launched on June 15, 2010) and their theoretical interpretation. The PREMOS package onboard PICARD comprises two experiments, one observing solar irradiance in five (two UV, one visible and two near infrared) spectral channels with filter radiometers the other measuring TSI with absolute radiometers. LYRA is a solar VUV radiometer onboard PROBA-2, which is a technologically oriented ESA micro-mission, and is observing the solar irradiance in two UV and two EUV spectral channels. The passbands of the UV channels in the both experiments were selected on the ground of relevance for the terrestrial ozone concentration. The PREMOS and LYRA measurements were carefully corrected for the degradation and cleaned for non-solar signatures. We provide a comparison with the VIRGO/SOHO and SOLSTICE+SIM/SORCE data. Both LYRA and PREMOS have observed several solar eclipses. The analysis of these observations allows us to accurately retrieve the center-to-limb variations (CLV) of the solar brightness, which play an important role in the modeling of the solar irradiance variability on the time scale of the solar rotation. We show that the calculations with the recently developed and published COde for Solar Irradiance (COSI) yield the CLV which are in a good agreement with the measurements. The irradiance in all channels shows a clear variability on time-scale of the solar rotation. The amplitude and the profile of the variability strongly depend on the wavelength. We use

  7. Multiscale entropy to distinguish physiologic and synthetic RR time series.

    PubMed

    Costa, M; Goldberger, A L; Peng, C-K

    2002-01-01

    We address the challenge of distinguishing physiologic interbeat interval time series from those generated by synthetic algorithms via a newly developed multiscale entropy method. Traditional measures of time series complexity only quantify the degree of regularity on a single time scale. However, many physiologic variables, such as heart rate, fluctuate in a very complex manner and present correlations over multiple time scales. We have proposed a new method to calculate multiscale entropy from complex signals. In order to distinguish between physiologic and synthetic time series, we first applied the method to a learning set of RR time series derived from healthy subjects. We empirically established selected criteria characterizing the entropy dependence on scale factor for these datasets. We then applied this algorithm to the CinC 2002 test datasets. Using only the multiscale entropy method, we correctly classified 48 of 50 (96%) time series. In combination with Fourier spectral analysis, we correctly classified all time series. PMID:14686448

  8. Thermal analysis of the FSP-1RR irradiation test

    SciTech Connect

    Webb, R.H.; Lyon, W.F. III

    1992-10-14

    The thermal analysis of four unirradiated fuel pins to be tested in the FSP-1RR fuels irradiation experiment was completed. This test is a follow-on experiment in the series of fuel pin irradiation tests conducted by the SP-100 Program in the Fast Flux Test Facility. One of the pins contains several meltwire temperature monitors within the fuel and the Li annulus. A post-irradiation examination will verify the accuracy of the pre-irradiation thermal analysis. The purpose of the pre-irradiation analysis was to determine the appropriate insulating gap gas compositions required to provide the design goal cladding operating temperatures and to ensure that the meltwire temperature ranges in the temperature monitored pin bracket peak irradiation temperatures. This paper discusses the methodology and summarizes the results of the analysis.

  9. Eclipsing and density effects on the spectral behavior of Beta Lyrae binary system in the UV

    NASA Astrophysics Data System (ADS)

    Sanad, M. R.

    2010-01-01

    We analyze both long and short high resolution ultraviolet spectrum of Beta Lyrae eclipsing binary system observed with the International Ultraviolet Explorer (IUE) between 1980 and 1989. The main spectral features are P Cygni profiles originating from different environments of Beta Lyrae. A set of 23 Mg II k&h spectral lines at 2800 Å, originating from the extended envelope [Hack, M., 1980. IAUS, 88, 271H], have been identified and measured to determine their fluxes and widths. We found that there is spectral variability for these physical parameters with phase, similar to that found for the light curve [Kondo, Y., McCluskey, G.E., Jeffery, M.M.S., Ronald, S.P., Carolina, P.S. McCluskey, Joel, A.E., 1994. ApJ, 421, 787], which we attribute to the eclipse effects [Ak, H., Chadima, P., Harmanec, P., Demircan, O., Yang, S., Koubský, P., Škoda, P., Šlechta, M., Wolf, M., Božić, H., 2007. A&A, 463, 233], in addition to the changes of density and temperature of the region from which these lines are coming, as a result of the variability of mass loss from the primary star to the secondary [Hoffman, J.L., Nordsieck, K.H., Fox, G.K., 1998. AJ, 115, 1576; Linnell, A.P., Hubeny, I., Harmanec, P., 1998. ApJ, 509, 379]. Also we present a study of Fe II spectral line at 2600 Å, originating from the atmosphere of the primary star [Hack, M., 1980. IAUS, 88, 271H]. We found spectral variability of line fluxes and line widths with phase similar to that found for Mg II k&h lines. Finally we present a study of Si IV spectral line at 1394 Å, originating from the extended envelope [Hack, M., 1980. IAUS, 88, 271H]. A set of 52 Si IV spectral line at 1394 Å have been identified and measured to determine their fluxes and widths. Also we found spectral variability of these physical parameters with phase similar to that found for Mg II k&h and Fe II spectral lines.

  10. 76 FR 65136 - Airworthiness Directives; Rolls-Royce plc (RR) Turbofan Engines

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-10-20

    ...-07, Amendment 39-166679 (76 FR 24793, May 3, 2011), and adding the following new AD: Rolls-Royce plc..., Amendment 39-16669 (76 FR 24793, May 3, 2011). (c) Applicability This AD applies to Rolls-Royce plc (RR... Directives; Rolls-Royce plc (RR) Turbofan Engines AGENCY: Federal Aviation Administration (FAA), DOT....

  11. 27. RAILROAD, RR. BRIDGE MISSISSIPPI, CLAY CO. WAVERLY 1.5 mi. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    27. RAILROAD, RR. BRIDGE MISSISSIPPI, CLAY CO. WAVERLY 1.5 mi. S of MS. 50 Stress Sheet of 1888 Bridge: Conroy & Sinks, Consulting Engineers, Chicago. July 21, 1910. DWG #978. Act. size around border: 18x11 in. Credit: Columbus and Greenville RR, Columbus, Ms. Sarcone Photography, Columbus, Ms. Sep 1978. - Bridges of the Upper Tombigbee River Valley, Columbus, Lowndes County, MS

  12. 28. RAILROAD, RR. BRIDGE MISSISSIPPI, CLAY CO. WAVERLY 1.5 mi. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    28. RAILROAD, RR. BRIDGE MISSISSIPPI, CLAY CO. WAVERLY 1.5 mi. S of MS. 50 Detail: Turn machinery. DWG S-3-325. Contr # 7236. upper right quarter of sheet: plan & longitudinal elevation of turn table.. July 1914. Credit: Columbus and Greenville RR, Columbus, Ms. Sarcone Photocopy, Columbus, Ms. Sep 1978. - Bridges of the Upper Tombigbee River Valley, Columbus, Lowndes County, MS

  13. 31. RAILROAD, RR BRIDGE MISSISSIPPI, CLAY CO., WAVERLY 1.5 mi. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    31. RAILROAD, RR BRIDGE MISSISSIPPI, CLAY CO., WAVERLY 1.5 mi. S of MS. 50 Detail: Turn machinery. DWG S-3-325. Contr. #7236. Upper left quarter of sheet: plan and longitudinal elevation of Wedges. July 1914. Credit: Columbus and Greenville RR, Columbus, Ms. Sarcone Photography, Columbus, Ms. Sep 1978 - Bridges of the Upper Tombigbee River Valley, Columbus, Lowndes County, MS

  14. 19. BLUEPRINT, RR BRIDGE MISSISSIPPI, CLAY CO., WAVERLY 1.5 mi. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    19. BLUEPRINT, RR BRIDGE MISSISSIPPI, CLAY CO., WAVERLY 1.5 mi. S of Ms. 50 Map of Tombigbee River at Waverly, 'Proposed Crossing.' 12 May 1888. Credt: Columbus & Greenville, RR, Columbus, Ms. DWG S-3-343. Sarcone Photography, ColumbuS, Ms. Sept 1978. - Bridges of the Upper Tombigbee River Valley, Columbus, Lowndes County, MS

  15. 30. RAILROAD, RR BRIDGE MISSISSIPPI, CLAY CO., WAVERLY 1.5 mi. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    30. RAILROAD, RR BRIDGE MISSISSIPPI, CLAY CO., WAVERLY 1.5 mi. S of MS. 50 Detail: Turn machinery. DWG S-3-325. Contr. #7236. Lower right quarter of sheet: Lateral elevation of turn table. July 1914. Credit: Columbus and Greenville RR, Columbus, MS. Sarcone Photography, Columbus, Ms. Sep 1978. - Bridges of the Upper Tombigbee River Valley, Columbus, Lowndes County, MS

  16. 29. RAILROAD, RR BRIDGE MISSISSIPPI, CLAY CO., WAVERLY 1.5. mi. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    29. RAILROAD, RR BRIDGE MISSISSIPPI, CLAY CO., WAVERLY 1.5. mi. S of MS. 50 Detail: Turn machinery. DWG S-3-325. Contr. #7236. Lower right quarter of sheet: Lateral elevation of turn table. July 1914. Credit: Columbus and Greenville RR, Columbus, Ms. Sarcone Photography, Columbus, Ms. Sep 1978. - Bridges of the Upper Tombigbee River Valley, Columbus, Lowndes County, MS

  17. 22. RAILROAD, RR BRIDGE MISSISSIPPI, CLAY CO., WAVERLY 1.5 mi. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    22. RAILROAD, RR BRIDGE MISSISSIPPI, CLAY CO., WAVERLY 1.5 mi. S of MS. 50 Proposed 218-foot turn span, submitted by the Wisconsin Bridge & Iron Co., Milwaukee, Wisconsin 8 May 1914. Act size: approx. 23x34 in. Credit: Columbus & Greenville RR, Columbus, Ms. Sarcone Photography, Columbus, MS. Sep 1978. - Bridges of the Upper Tombigbee River Valley, Columbus, Lowndes County, MS

  18. 21. RAILROAD, RR. BRIDGE MISSISSIPPI, CLAY CO., WAVERLY 1.5 mi. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    21. RAILROAD, RR. BRIDGE MISSISSIPPI, CLAY CO., WAVERLY 1.5 mi. S of Ms. 50 Proposed 218-foot turn span, design #2339 of Virginia Bridge and Iron Co., Roanoke, Va. 13 May 1914. Act. size: 16x11 in. Credit: Columbus & Greenville RR, Columbus, Ms. Sarcone Photography, Columbus, Ms. - Bridges of the Upper Tombigbee River Valley, Columbus, Lowndes County, MS

  19. Mapping the outer bulge with RRab stars from the VVV Survey

    NASA Astrophysics Data System (ADS)

    Gran, F.; Minniti, D.; Saito, R. K.; Zoccali, M.; Gonzalez, O. A.; Navarrete, C.; Catelan, M.; Contreras Ramos, R.; Elorrieta, F.; Eyheramendy, S.; Jordán, A.

    2016-07-01

    Context. The VISTA Variables in the Vía Láctea (VVV) is a near-IR time-domain survey of the Galactic bulge and southern plane. One of the main goals of this survey is to reveal the 3D structure of the Milky Way through their variable stars. In particular, enormous numbers of RR Lyrae stars have been discovered in the inner regions of the bulge (-8° ≲ b ≲ -1°) by optical surveys such as OGLE and MACHO, but leaving an unexplored window of more than ~47 sq deg (-10.0° ≲ ℓ ≲ + 10.7° and - 10.3° ≲ b ≲ -8.0°) observed by the VVV Survey. Aims: Our goal is to characterize the RR Lyrae stars in the outer bulge in terms of their periods, amplitudes, Fourier coefficients, and distances in order to evaluate the 3D structure of the bulge in this area. The distance distribution of RR Lyrae stars will be compared to that of red clump stars, which is known to trace a X-shaped structure, in order to determine whether these two different stellar populations share the same Galactic distribution. Methods: A search for RR Lyrae stars was performed in more than ~47 sq deg at low Galactic latitudes (-10.3° ≲ b ≲ -8.0°). In the procedure the χ2 value and analysis of variance (AoV) statistic methods were used to determine the variability and periodic features of the light curves, respectively. To prevent misclassifications, the analysis was performed only on the fundamental mode RR Lyrae stars (RRab) owing to similarities found in the near-IR light curve shapes of contact eclipsing binaries (W UMa) and first overtone RR Lyrae stars (RRc). On the other hand, the red clump stars of the same analyzed tiles were selected, and cuts in the color-magnitude diagram were applied and the maximum distance restricted to ~20 kpc in order to construct a similar catalog in terms of distances and covered area compared to the RR Lyrae stars. Results: We report the detection of more than 1000 RR Lyrae ab-type stars in the VVV Survey located in the outskirts of the Galactic bulge

  20. Reconstruction of the solar EUV irradiance as observed with PROBA2/LYRA

    NASA Astrophysics Data System (ADS)

    Haberreiter, Margit; Delouille, Veronique; Del Zanna, Giulio; Ermolli, Ilaria; Kretzschmar, Matthieu; Mampeay, Benjamin; Dominique, Marie; Schmutz, Werner

    2014-05-01

    The solar EUV spectrum has important effects on the upper atmosphere of the Earth and any planet. For a detailed investigation of these effects it is important to have a constistent data series of the EUV spectral irradiance available. Here, we present the reconstruction of the solar EUV irradiance based on PSPT and SOHO/EIT images and along with synthetic spectra calculated for six different coronal features representing the brightness variation of the solar atmosphere. The EIT images are segmented with the SPoCA tool which allows to identify the features based on a consistent brightness classification for each feature. With the SOLMOD code we then calculate intensity spectra for 10 nm to 100 nm for each of the coronal feature. Weighting the intensity spectra with the area covered by each of the features yields the temporal variation of the EUV spectrum. The reconstructed time series is then validated against the spectral irradiance as observed with PROBA2/LYRA. This is an important step towards the understanding of the variations of the solar EUV spectrum and ultimately its detailed effect on the Earth's upper atmosphere.

  1. Reconstruction of the Solar EUV Irradiance as observed with SOHO/SEM and PROBA2/LYRA

    NASA Astrophysics Data System (ADS)

    Haberreiter, M.; Delouille, V.; Mampaey, B.; Verbeeck, C.; Del Zanna, G.; Ermolli, I.; Kretzschmar, M.; Dominique, M.; Wieman, S. R.; Schmutz, W. K.

    2013-12-01

    The solar EUV spectrum has important effects on the Earth's upper atmosphere. For a detailed investigation of these effects it is important to have a constistent data series of the EUV spectral irradiance available. Here, we present the reconstruction of the solar EUV irradiance based on PSPT and SOHO/EIT images and along with synthetic spectra calculated for six different coronal features representing the brightness variation of the solar atmosphere. The EIT images are segmented with the SPoCA tool which allows to identify the features based on a consistent brightness classification for each feature. With the SOLMOD code we then calculate intensity spectra for 10 nm to 100 nm for each of the coronal feature. Weighting the intensity spectra with the area covered by each of the features yields the temporal variation of the EUV spectrum. The reconstructed time series is then validated against the spectral irradiance as observed with SOHO/SEM and PROBA2/LYRA. Our approach leads to a very good agreement between the reconstructed and the observed spectral irradiance. This is an important step towards the understanding of the variations of the solar EUV spectrum and ultimately its effect on the Earth's upper atmosphere.

  2. Exact solutions of bulk viscous with string cloud attached to strange quark matter for higher dimensional FRW universe in Lyra geometry

    NASA Astrophysics Data System (ADS)

    Ćaǧlar, Halife; Aygün, Sezgin

    2016-03-01

    In this study, we have investigated bulk viscous with strange quark matter attached to the string cloud for higher dimensional Friedman-Robertson-Walker (FRW) universe in Lyra geometry. By using varying deceleration parameter and conservation equations we have solved Einstein Field Equations (EFE's) and obtained generalized exact solutions for our model. Also we have found that string is not survived for bulk viscous with strange quark matter attached to the string cloud in framework higher dimensional FRW universe in Lyra geometry. This result agrees with Kiran and Reddy, Krori et al, Sahoo and Mishra and Mohanty et al. in four and five dimensions.

  3. Important influence of respiration on human R-R interval power spectra is largely ignored.

    PubMed

    Brown, T E; Beightol, L A; Koh, J; Eckberg, D L

    1993-11-01

    Frequency-domain analyses of R-R intervals are used widely to estimate levels of autonomic neural traffic to the human heart. Because respiration modulates autonomic activity, we determined for nine healthy subjects the influence of breathing frequency and tidal volume on R-R interval power spectra (fast-Fourier transform method). We also surveyed published literature to determine current practices in this burgeoning field of scientific inquiry. Supine subjects breathed at rates of 6, 7.5, 10, 15, 17.1, 20, and 24 breaths/min and with nominal tidal volumes of 1,000 and 1,500 ml. R-R interval power at respiratory and low (0.06-0.14 Hz) frequencies declined significantly as breathing frequency increased. R-R interval power at respiratory frequencies was significantly greater at a tidal volume of 1,500 than 1,000 ml. Neither breathing frequency nor tidal volume influenced average R-R intervals significantly. Our review of studies reporting human R-R interval power spectra showed that 51% of the studies controlled respiratory rate, 11% controlled tidal volume, and 11% controlled both respiratory rate and tidal volume. The major implications of our analyses are that breathing parameters strongly influence low-frequency as well as respiratory frequency R-R interval power spectra and that this influence is largely ignored in published research. PMID:8307890

  4. Important influence of respiration on human R-R interval power spectra is largely ignored

    NASA Technical Reports Server (NTRS)

    Brown, T. E.; Beightol, L. A.; Koh, J.; Eckberg, D. L.

    1993-01-01

    Frequency-domain analyses of R-R intervals are used widely to estimate levels of autonomic neural traffic to the human heart. Because respiration modulates autonomic activity, we determined for nine healthy subjects the influence of breathing frequency and tidal volume on R-R interval power spectra (fast-Fourier transform method). We also surveyed published literature to determine current practices in this burgeoning field of scientific inquiry. Supine subjects breathed at rates of 6, 7.5, 10, 15, 17.1, 20, and 24 breaths/min and with nominal tidal volumes of 1,000 and 1,500 ml. R-R interval power at respiratory and low (0.06-0.14 Hz) frequencies declined significantly as breathing frequency increased. R-R interval power at respiratory frequencies was significantly greater at a tidal volume of 1,500 than 1,000 ml. Neither breathing frequency nor tidal volume influenced average R-R intervals significantly. Our review of studies reporting human R-R interval power spectra showed that 51% of the studies controlled respiratory rate, 11% controlled tidal volume, and 11% controlled both respiratory rate and tidal volume. The major implications of our analyses are that breathing parameters strongly influence low-frequency as well as respiratory frequency R-R interval power spectra and that this influence is largely ignored in published research.

  5. Sun-as-a-Star Observation of Flares in Lyman α by the PROBA2/LYRA Radiometer

    NASA Astrophysics Data System (ADS)

    Kretzschmar, M.; Dominique, M.; Dammasch, I. E.

    2013-08-01

    There are very few reports of flare signatures in the solar irradiance at H i Lyman α at 121.5 nm, i.e. the strongest line of the solar spectrum. The LYRA radiometer onboard PROBA2 has observed several flares for which unambiguous signatures have been found in its Lyman-α channel. Here we present a brief overview of these observations followed by a detailed study of one of them: the M2 flare that occurred on 8 February 2010. For this flare, the flux in the LYRA Lyman-α channel increased by 0.6 %, which represents about twice the energy radiated in the GOES soft X-ray channel and is comparable with the energy radiated in the He ii line at 30.4 nm. The Lyman-α emission represents only a minor part of the total radiated energy of this flare, for which a white-light continuum was detected. Additionally, we found that the Lyman-α flare profile follows the gradual phase but peaks before other wavelengths. This M2 flare was very localized and had a very brief impulsive phase, but more statistics are needed to determine if these factors influence the presence of a Lyman-α flare signal strong enough to appear in the solar irradiance.

  6. Photocopy of floor plan of the C.B. & Q. R.R ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Photocopy of floor plan of the C.B. & Q. R.R roundhouse and locomotive shops. June 1980. - Chicago, Burlington & Quincy Railroad, Roundhouse & Shops, Broadway & Spring Streets, Aurora, Kane County, IL

  7. Chicago, Burlington, & Quincy R.R car works aurora, ILL. Photocopy ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Chicago, Burlington, & Quincy R.R car works aurora, ILL. Photocopy of an undated lithograph based on an ambrotype by D.C. Pratt, C. 1857 - Chicago, Burlington & Quincy Railroad, Roundhouse & Shops, Broadway & Spring Streets, Aurora, Kane County, IL

  8. Mechanism of blood pressure and R-R variability: insights from ganglion blockade in humans

    NASA Technical Reports Server (NTRS)

    Zhang, Rong; Iwasaki, Kenichi; Zuckerman, Julie H.; Behbehani, Khosrow; Crandall, Craig G.; Levine, Benjamin D.; Blomqvist, C. G. (Principal Investigator)

    2002-01-01

    Spontaneous blood pressure (BP) and R-R variability are used frequently as 'windows' into cardiovascular control mechanisms. However, the origin of these rhythmic fluctuations is not completely understood. In this study, with ganglion blockade, we evaluated the role of autonomic neural activity versus other 'non-neural' factors in the origin of BP and R-R variability in humans. Beat-to-beat BP, R-R interval and respiratory excursions were recorded in ten healthy subjects (aged 30 +/- 6 years) before and after ganglion blockade with trimethaphan. The spectral power of these variables was calculated in the very low (0.0078-0.05 Hz), low (0.05-0.15 Hz) and high (0.15-0.35 Hz) frequency ranges. The relationship between systolic BP and R-R variability was examined by cross-spectral analysis. After blockade, R-R variability was virtually abolished at all frequencies; however, respiration and high frequency BP variability remained unchanged. Very low and low frequency BP variability was reduced substantially by 84 and 69 %, respectively, but still persisted. Transfer function gain between systolic BP and R-R interval variability decreased by 92 and 88 % at low and high frequencies, respectively, while the phase changed from negative to positive values at the high frequencies. These data suggest that under supine resting conditions with spontaneous breathing: (1) R-R variability at all measured frequencies is predominantly controlled by autonomic neural activity; (2) BP variability at high frequencies (> 0.15 Hz) is mediated largely, if not exclusively, by mechanical effects of respiration on intrathoracic pressure and/or cardiac filling; (3) BP variability at very low and low frequencies (< 0.15 Hz) is probably mediated by both sympathetic nerve activity and intrinsic vasomotor rhythmicity; and (4) the dynamic relationship between BP and R-R variability as quantified by transfer function analysis is determined predominantly by autonomic neural activity rather than other

  9. Microcystin-RR exposure results in growth impairment by disrupting thyroid endocrine in zebrafish larvae.

    PubMed

    Xie, Liqiang; Yan, Wei; Li, Jing; Yu, Liqin; Wang, Jianghua; Li, Guangyu; Chen, Nan; Steinman, Alan D

    2015-07-01

    Recent studies have shown that cyanobacteria-derived microcystins (MCs) have the potential to disrupt endocrine systems. However, the effects of microcystin-RR (MC-RR) and their underlying mechanisms are poorly resolved in fish. In this study, MC-RR exposure through submersion caused serious developmental toxicity, such as growth delay and depressed heart rates in zebrafish larvae. We also detected decreased levels of thyroid hormones (THs), suggesting that MC-RR-triggered thyroid endocrine disruption might contribute to the growth impairment observed in developing zebrafish. To further our understanding of mechanisms of MC-RR-induced endocrine toxicity, quantitative real-time PCR (QPCR) analysis was performed on hypothalamic-pituitary-thyroid (HPT) axis related genes, i.e., corticotropin-releasing factor (CRF), thyroid-stimulating hormone (TSH), sodium/iodide symporter (NIS), thyroglobulin (TG), thyroid receptors (TRα and TRβ) and iodothyronine deiodinases (Dio1 and Dio2), of developing zebrafish embryos exposed to 0, 0.3, 1.0 or 3.0mgL(-1) MC-RR until 96h post-fertilization. Our results showed that transcription pattern of HPT axis related genes were greatly changed by MC-RR exposure, except TG gene. Furthermore, western blot was used to validate the results of gene expression. The results showed protein synthesis of TG was not affected, while that of NIS was significantly up-regulated, which are in accordance with gene expression. The overall results indicated that exposure to MC-RR can induce developmental toxicity, which might be associated with thyroid endocrine disruption in developing zebrafish larvae. PMID:25897773

  10. 25. RAILROAD, RR BRIDGE MISSISSIPPI, CLAY CO., WAVERLY 1.5 mi. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    25. RAILROAD, RR BRIDGE MISSISSIPPI, CLAY CO., WAVERLY 1.5 mi. S of MS. 50 Proposed 218-foot turn span, submitted by the American Bridge Co., Pittsburg, Pa., 15 May 1914. Inquiry # P-19242. Act. size: approx: 23x24 in. Credit: Columbus and Greenville RR, columbus, MS. Sarcone Photography, Columbus, Ms. Sep 1978. - Bridges of the Upper Tombigbee River Valley, Columbus, Lowndes County, MS

  11. 26. RAILROAD, RR BRIDGE MISSISSIPPI, CLAY CO., WAVERLY 1.5 mi. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    26. RAILROAD, RR BRIDGE MISSISSIPPI, CLAY CO., WAVERLY 1.5 mi. S of MS. 50 Proposed 218-foot deck, plate-girder turn span, submitted by the Wisconsin Bridge and Iron Co., Milwaukee, Wisc. May 15 1914. Act size: approx. 23x34 in. Credit: columbus and Greenville RR, Columbus, Ms. Sarcone Photography, Columbus, Ms. Sep 1978. - Bridges of the Upper Tombigbee River Valley, Columbus, Lowndes County, MS

  12. 23. RAILROAD, RR BRIDGE MISSISSIPPI, CLAY CO., WAVERLY 1.5 mi. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    23. RAILROAD, RR BRIDGE MISSISSIPPI, CLAY CO., WAVERLY 1.5 mi. S of MS. 50 Southern R'wy Co. in Ms. Repairs to Tombigbee River Bridge' gears and turn machinery. DWG # S. 30303. Scale: 1-1/2' = l'. July 21, 1913. Credit: Columbus & Greenville RR, Columbus, Ms. Sarcone Photography, Columbus, Ms. Sep 1978. - Bridges of the Upper Tombigbee River Valley, Columbus, Lowndes County, MS

  13. 24. RAILROAD, RR BRIDGE MISSISSIPPI, CLAY CO., WAVERLY 1.5 mi. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    24. RAILROAD, RR BRIDGE MISSISSIPPI, CLAY CO., WAVERLY 1.5 mi. S of MS. 50 Southern R'wy; Co., in Ms. Present and proposed draw bridge over Tombigbee River.' Elevations and Plan, with falsework. Wisconsin Bridge and Iron Co., Milwaukee, Wisc., DWG #S. 3-303. Last Revision, Jan. 11 1915. Act. size: 23x34 in. Credit: Columbus and Greenville Rr, Columbus, Ms. Sarcone Photography, Columbus, MS. Sep 1978. - Bridges of the Upper Tombigbee River Valley, Columbus, Lowndes County, MS

  14. Genetic analysis of low survival rate of pups in RR/Sgn inbred mice.

    PubMed

    Suto, Jun-ichi

    2015-07-01

    Newborn offspring of the inbred mouse RR/Sgn strain have a low survival rate prior to weaning. We hypothesized that this is a consequence of an inferior nurturing ability of RR/Sgn mothers and that RR/Sgn mothers have a tendency to lose their pups. We performed quantitative trait locus (QTL) mapping for inferior nurturing ability and tendency to lose pups in RR/Sgn mothers. The number of pups was adjusted to 6 per dam on the day of delivery, and the number of surviving pups and their total weight (litter weight) were scored at 12 days after birth. Nurturing ability was evaluated by litter weight, and tendency to lose pups was evaluated by scoring whether or not the mothers lost their pups. For litter weight, we identified one significant QTL on chromosome 4 and three suggestive QTLs on chromosomes 7, 9 and 17. The RR/Sgn allele was associated with lower litter weight at all loci. For the tendency to lose pups, we identified three suggestive QTLs on chromosomes 4, 9 and 16. The RR/Sgn allele was associated with an increased tendency to lose pups at all loci. These results supported our hypothesis that the low survival rate phenotype was attributable, at least in part, to a phenotype whereby mothers display inferior nurturing ability and a tendency to lose pups. Thus, it suggests that these two traits share genetic basis. PMID:25754650

  15. The Hercules-Lyra association revisited. New age estimation and multiplicity study

    NASA Astrophysics Data System (ADS)

    Eisenbeiss, T.; Ammler-von Eiff, M.; Roell, T.; Mugrauer, M.; Adam, Ch.; Neuhäuser, R.; Schmidt, T. O. B.; Bedalov, A.

    2013-08-01

    Context. The Hercules-Lyra association, a purported nearby young moving group, contains a few tens of zero age main sequence stars of spectral types F to M. The existence and the properties of the Her-Lyr association are controversial and have been discussed in the literature. Aims: The present work reassesses the properties and the member list of the Her-Lyr association based on kinematics and age indicators. Many objects form multiple systems or have low-mass companions and so we need to properly account for multiplicity. Methods: We use our own new imaging observations and archival data to identify multiple systems. The colors and magnitudes of kinematic candidates are compared to isochrones. We derive further information on the age based on Li depletion, rotation, and coronal and chromospheric activity. A set of canonical members is identified to infer mean properties. Membership criteria are derived from the mean properties and used to discard non-members. Results: The candidates selected from the literature belong to 35 stellar systems, 42.9% of which are multiple. Four multiple systems (V538 Aur, DX Leo, V382 Ser, and HH Leo) are confirmed in this work by common proper motion. An orbital solution is presented for the binary system which forms a hierarchical triple with HH Leo. Indeed, a group of candidates displays signatures of youth. Seven canonical members are identified The distribution of Li equivalent widths of canonical Her-Lyr members is spread widely and is similar to that of the Pleiades and the UMa group. Gyrochronology gives an age of 257 ± 46 Myr which is roughly in between the ages of the Pleiades and the Ursa Major group. The measures of chromospheric and coronal activity support the young age. Four membership criteria are presented based on kinematics, lithium equivalent width, chromospheric activity, and gyrochronological age. In total, eleven stars are identified as certain members including co-moving objects plus additional 23 possible

  16. A Cosmological Model of the Early Universe Based on ECG with Variable Λ-Term in Lyra Geometry

    NASA Astrophysics Data System (ADS)

    Saadat, H.

    2016-05-01

    In this paper, we study interacting extended Chaplygin gas as dark matter and quintessence scalar field as dark energy with an effective Λ-term in Lyra manifold. As we know Chaplygin gas behaves as dark matter at the early universe while cosmological constant at the late time. Modified field equations are given and motivation of the phenomenological models discussed in details. Four different models based on the interaction term are investigated in this work. Then, we consider other models where Extended Chaplygin gas and quintessence field play role of dark matter and dark energy respectively with two different forms of interaction between the extended Chaplygin gas and quintessence scalar field for both constant and varying Λ. Concerning to the mathematical hardness of the problems we discuss results numerically and graphically. Obtained results give us hope that proposed models can work as good models for the early universe with later stage of evolution containing accelerated expansion.

  17. Yet Another Spectro-Interferometric Study of The Gas Distribution in The Enigmatic Semi-Detached Binary β Lyrae

    NASA Astrophysics Data System (ADS)

    Nemravová, J.; Mourard, D.; Harmanec, P.; Meilland, A.

    2015-12-01

    The majority of close binaries undergo episodes of mass transfer between their components, which completely change their further evolution. Simulations and observations agree that the mass transfer has two phases: i) short and rapid one, and ii) long and slow one. The bulk of the mass is likely exchanged during the rapid phase, but due to its shortness, systems undergoing this phase are rare, but they hold the key to understanding of the process. One system that is either undergoing the rapid mass transfer phase or is in a transient phase between the two phases is β Lyrae. Our goal is to map the distribution of circumstellar gas in the system. To achieve it, a series of spectro-interferometric observations acquired with the optical instrument VEGA/CHARA are investigated. Here we present our tools and preliminary results of our analysis.

  18. Semiautomatic validation of RR time series in an ECG stress test database

    NASA Astrophysics Data System (ADS)

    Armijos, Jairo; García, David; Astudillo, Darwin; Palacio-Baus, Kenneth; Medina, Rubén.; Wong, Sara

    2015-12-01

    This paper reports an automatic method for characterizing the quality of the RR-time series in the stress test database known as DICARDIA. The proposed methodology is simple and consists in subdividing the RR time series in a set of windows for estimating the quantity of artifacts based on a threshold value that depends on the standard deviation of RR-time series for each recorded lead. In a first stage, a manual annotation was performed considering four quality classes for the RR-time series (Reference lead, Good Lead, Low Quality Lead and Useless Lead). Automatic annotation was then performed varying the number of windows and threshold value for the standard deviation of the RR-time series. The metric used for evaluating the quality of the annotation was the Matching Ratio. The best results were obtained using a higher number of windows and considering only three classes (Good Lead, Low Quality Lead and Useless). The proposed methodology allows the utilization of the online available DICARDIA Stress Test database for different types of research.

  19. Mechanism of blood pressure and R-R variability: insights from ganglion blockade in humans

    PubMed Central

    Zhang, Rong; Iwasaki, Kenichi; Zuckerman, Julie H; Behbehani, Khosrow; Crandall, Craig G; Levine, Benjamin D

    2002-01-01

    Spontaneous blood pressure (BP) and R-R variability are used frequently as ‘windows’ into cardiovascular control mechanisms. However, the origin of these rhythmic fluctuations is not completely understood. In this study, with ganglion blockade, we evaluated the role of autonomic neural activity versus other ‘non-neural’ factors in the origin of BP and R-R variability in humans. Beat-to-beat BP, R-R interval and respiratory excursions were recorded in ten healthy subjects (aged 30 ± 6 years) before and after ganglion blockade with trimethaphan. The spectral power of these variables was calculated in the very low (0.0078-0.05 Hz), low (0.05-0.15 Hz) and high (0.15-0.35 Hz) frequency ranges. The relationship between systolic BP and R-R variability was examined by cross-spectral analysis. After blockade, R-R variability was virtually abolished at all frequencies; however, respiration and high frequency BP variability remained unchanged. Very low and low frequency BP variability was reduced substantially by 84 and 69 %, respectively, but still persisted. Transfer function gain between systolic BP and R-R interval variability decreased by 92 and 88 % at low and high frequencies, respectively, while the phase changed from negative to positive values at the high frequencies. These data suggest that under supine resting conditions with spontaneous breathing: (1) R-R variability at all measured frequencies is predominantly controlled by autonomic neural activity; (2) BP variability at high frequencies (> 0.15 Hz) is mediated largely, if not exclusively, by mechanical effects of respiration on intrathoracic pressure and/or cardiac filling; (3) BP variability at very low and low frequencies (< 0.15 Hz) is probably mediated by both sympathetic nerve activity and intrinsic vasomotor rhythmicity; and (4) the dynamic relationship between BP and R-R variability as quantified by transfer function analysis is determined predominantly by autonomic neural activity rather than

  20. The Outer Galactic Halo As Probed By RR Lyr Stars From the Palomar Transient Facility + Keck

    NASA Astrophysics Data System (ADS)

    Cohen, Judith; Sesar, Branimir; Banholzer, Sophianna

    2016-08-01

    We present initial results from our study of the outer halo of the Milky Way using a large sample of RR Lyr(ab) variables datamined from the archives of the Palomar Transient Facility. Of the 464 RR Lyr in our sample with distances exceeding 50 kpc, 62 have been observed spectroscopically at the Keck Observatory. vr and σ(vr ) are given as a function of distance between 50 and 110 kpc, and a very preliminary rather low total mass for the Milky Way out to 110 kpc of ~7+/-1.5×1011 M ⊙ is derived from our data.

  1. Mechanisms underlying very-low-frequency RR-interval oscillations in humans

    NASA Technical Reports Server (NTRS)

    Taylor, J. A.; Carr, D. L.; Myers, C. W.; Eckberg, D. L.

    1998-01-01

    BACKGROUND: Survival of post-myocardial infarction patients is related inversely to their levels of very-low-frequency (0.003 to 0.03 Hz) RR-interval variability. The physiological basis for such oscillations is unclear. In our study, we used blocking drugs to evaluate potential contributions of sympathetic and vagal mechanisms and the renin-angiotensin-aldosterone system to very-low-frequency RR-interval variability in 10 young healthy subjects. METHODS AND RESULTS: We recorded RR intervals and arterial pressures during three separate sessions, with the patient in supine and 40 degree upright tilt positions, during 20-minute frequency (0.25 Hz) and tidal volume-controlled breathing after intravenous injections: saline (control), atenolol (0.2 mg/kg, beta-adrenergic blockade), atropine sulfate (0.04 mg/kg, parasympathetic blockade), atenolol and atropine (complete autonomic blockade), and enalaprilat (0.02 mg/kg, ACE blockade). We integrated fast Fourier transform RR-interval spectral power at very low (0.003 to 0.03 Hz), low (0.05 to 0. 15 Hz), and respiratory (0.2 to 0.3 Hz) frequencies. Beta-adrenergic blockade had no significant effect on very-low- or low-frequency RR-interval power but increased respiratory frequency power 2-fold. ACE blockade had no significant effect on low or respiratory frequency RR-interval power but modestly (approximately 21%) increased very-low-frequency power in the supine (but not upright tilt) position (P<0.05). The most profound effects were exerted by parasympathetic blockade: Atropine, given alone or with atenolol, abolished nearly all RR-interval variability and decreased very-low-frequency variability by 92%. CONCLUSIONS: Although very-low-frequency heart period rhythms are influenced by the renin-angiotensin-aldosterone system, as low and respiratory frequency RR-interval rhythms, they depend primarily on the presence of parasympathetic outflow. Therefore the prognostic value of very-low-frequency heart period oscillations may

  2. Periodic variability in the symbiotic stars SY MUSCAE and RR Telescopii

    NASA Astrophysics Data System (ADS)

    Kenyon, S. J.; Bateson, F. M.

    1984-04-01

    The authors discuss periodic brightness variations in the symbiotic stars SY Mus and RR Tel. The 627.0-day variation in SY Mus is a result of binary motion, as the 0.6-mag amplitude is due to the reflection effect and an eclipse of the hot source by its red-giant companion. RR Tel has a 374-day cycle with an amplitude of 0.25 mag. This value for the period is nearly identical to that observed before the 1944 outburst and recently confirmed by infrared observations, and is the pulsational period of a Mira-like long-period variable.

  3. Prediction of left ventricular peak ejection velocity by preceding and prepreceding RR intervals in atrial fibrillation: a new method to adjust the influence between two intervals.

    PubMed Central

    Ko, Hong Sook; Lee, Kwang Je; Kim, Sang Wook; Kim, Tae Ho; Kim, Chee Jeong; Ryu, Wang Seong

    2002-01-01

    In atrial fibrillation, cardiac performance is dependent on both preceding RR (RR-1) and prepreceding RR (RR-2) intervals. However, relative contributions were not well defined. Left ventricular outflow peak ejection velocity (Vpe) was measured by echocardiography from 21 patients. The relation between RR-1 and Vpe could be divided into two zones; steep slope in short RR-1 intervals (< or =0.5 sec) and plateau in long RR-1 intervals (> 0.5 sec). RR-2 had a weak negative association with Vpe. The mean squared correlation coefficient (r2) between RR-2 and Vpe was 0.15 +/-0.13 and improved to 0.29+/-0.21 (p<0.001), when coordinates with RR-1 < or =0.5 sec were excluded. The RR-1 was positively associated with Vpe. The mean r2 between RR-1 and Vpe was 0.52+/-0.17 and improved to 0.72+/-0.11 (p<0.001), when adjusted by RR-2. Simple linear regression analysis showed that mean RR interval, age, fractional shortening (FS), and mean peak velocity were negatively correlated with modified r2 between RR-2 and Vpe. Multiple stepwise regression analysis revealed that mean RR interval (r2=0.32) and FS (r2=0.16) were significant. In summary, simple modification could improve the relationship of both RR-1 and RR-2 with cardiac performance. RR-2 might play a more role in cardiac performance than previously expected, and when cardiac function was impaired. PMID:12482995

  4. Fate of Southern Green Egg Masses in BT-Cotton, RR Cotton, Soybeans and Peanuts

    Technology Transfer Automated Retrieval System (TEKTRAN)

    There is a need to determine the life history of stink bugs relative to major crops in the southeastern US. To this end, we investigated Southern green stink bug egg mortality by placing sentinel egg masses in plots of soybean, Bt-cotton, Round up Ready (RR) cotton and peanut plants in the Southeas...

  5. Genome Sequence of Stenotrophomonas maltophilia RR-10, Isolated as an Endophyte from Rice Root

    PubMed Central

    Zhu, Bo; Liu, He; Tian, Wen-Xiao; Fan, Xiao-Ying; Li, Bin; Zhou, Xue-Ping

    2012-01-01

    Stenotrophomonas maltophilia is an endophyte which plays important roles in agricultural production as a plant growth-promoting bacterium. Here, we present the draft genome sequence of strain RR-10, which was isolated from a rice root in a rice field of China. PMID:22328769

  6. 16. The Baltimore & Ohio R.R System, Division BaltimoreEast, Bridge ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    16. The Baltimore & Ohio R.R System, Division Baltimore-East, Bridge No 13-A, Branch Philadelphia. Baltimore: Office of Engineer of Bridges, 1945. Copy of drawing located at the Baltimore County Department of Public Works, Towson, Maryland. - Allender Road Bridge, Spanning CSX Transportation railroad tracks at Allender Road, White Marsh, Baltimore County, MD

  7. 76 FR 64283 - Airworthiness Directives; Rolls-Royce plc (RR) Turbofan Engines

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-10-18

    ... Federal Aviation Administration 14 CFR Part 39 RIN 2120-AA64 Airworthiness Directives; Rolls-Royce plc (RR... identified in this AD, contact Rolls-Royce plc, Corporate Communications, P.O. Box 31, Derby, England, DE248BJ; phone: 011-44-1332-242424; fax: 011-44-1332-245418 or e-mail from...

  8. 77 FR 13483 - Airworthiness Directives; Rolls-Royce plc (RR) Turbofan Engines

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-03-07

    ...-07 (76 FR 24793, May 3, 2011), or, have Rolls-Royce plc revise Alert Service Bulletin (ASB) No. RB...; AD 2012-04-13] RIN 2120-AA64 Airworthiness Directives; Rolls-Royce plc (RR) Turbofan Engines AGENCY... Rolls-Royce plc, Corporate Communications, P.O. Box 31, Derby, England, DE248BJ; phone:...

  9. 15. 'Southern Pacific R.R., One 236'0' Bet. End Pins S. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    15. 'Southern Pacific R.R., One 236'-0' Bet. End Pins S. Tr. Thro'. Draw Bridge over Sacramento River at Tehama, The Phoenix Bridge Co., Phoenixville, Pa., Jan'y 19th 98, Dwg. 585.' - Southern Pacific Railroad Shasta Route, Bridge No. 210.52, Milepost 210.52, Tehama, Tehama County, CA

  10. "D.L.&W. R.R. Profile for New Tunnel Through Bergen Hill" Plan ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    "D.L.&W. R.R. Profile for New Tunnel Through Bergen Hill" Plan Sheet. December 1, 1905. On file at New Jersey Transit Corporation Headquarters, Newark, New Jersey - Delaware, Lackawanna & Western Railroad, South Bergen Tunnel, Jersey City, Hudson County, NJ

  11. Stability of UV exposed RR-P3BT films by spectroscopic ellipsometry

    SciTech Connect

    Diware, Mangesh S.; Byun, J. S.; Hwang, S. Y.; Kim, T. J.; Kim, Y. D.

    2013-02-05

    Stability of regioregular poly(3-butylthiophene) (RR-P3BT) films under irradiation of ultra-violet (UV) light has been studied by spectroscopic ellipsometry at room temperature. Consistent decrease in dielectric function with UV exposure time showed the degree of degradation of polymer. This work suggests that, protective methods are mandatory to use this kind of material in optical devices.

  12. Toxicological Review of Cyanobacterial Toxins: Microcystins Lr, Rr, Yr and La (External Review Draft)

    EPA Science Inventory

    The National Center for Environmental Assessment has prepared the Toxicological Reviews of Cyanobacterial Toxins: Anatoxin-a, Cylindrospermopsin and Microcystins (LR, RR, YR and LA) as a series of dose-response assessments to support the health assessment of unregulated contamina...

  13. Meiotic Instability of the R-R Complex Arising from Displaced Intragenic Exchange and Intrachromosomal Rearrangement

    PubMed Central

    Robbins, T. P.; Walker, E. L.; Kermicle, J. L.; Alleman, M.; Dellaporta, S. L.

    1991-01-01

    The R complex of Zea mays encodes a tissue-specific transcriptional activator of the anthocyanin pigment biosynthetic pathway. Certain R alleles comprise two genetically distinct components that confer the plant (P) and seed (S) aspects of the pigmentation pattern. These alleles are meiotically unstable, losing (P) or (S) function, often accompanied by exchange of flanking markers. We show that the (P) component consists of a single gene within the R-r complex, whereas the (S) component is part of a more complex arrangement of multiple R genes or gene subfragments. A third, cryptic region of the complex, termed (Q), consists of a truncated R sequence. The analysis of R-r crossover derivative alleles shows they arise from unequal exchange between the (P) gene and one of several distinct regions of the R-r complex. Restriction site polymorphisms were used to show that most of these unequal exchanges are intragenic. The frequency of displaced intragenic recombination is comparable to previous estimates for intragenic recombination in maize involving genes that are not duplicated. These exchange events have been used to determine the arrangement of components within the complex and their orientation in the chromosome. We also show that localized rearrangements in the (P) or (S) components are responsible for noncrossover derivative alleles. The organization of R-r has implications for these noncrossover derivatives and models for their origin are discussed. PMID:1682214

  14. Fundamental relations between short-term RR interval and arterial pressure oscillations in humans

    NASA Technical Reports Server (NTRS)

    Taylor, J. A.; Eckberg, D. L.

    1996-01-01

    BACKGROUND: One of the principal explanations for respiratory sinus arrhythmia is that it reflects arterial baroreflex buffering of respiration-induced arterial pressure fluctuations. If this explanation is correct, then elimination of RR interval fluctuations should increase respiratory arterial pressure fluctuations. METHODS AND RESULTS: We measured RR interval and arterial pressure fluctuations during normal sinus rhythm and fixed-rate atrial pacing at 17.2+/-1.8 (SEM) beats per minute greater than the sinus rate in 16 healthy men and 4 healthy women, 20 to 34 years of age. Measurements were made during controlled-frequency breathing (15 breaths per minute or 0.25 Hz) with subjects in the supine and 40 degree head-up tilt positions. We characterized RR interval and arterial pressure variabilities in low-frequency (0.05 to 0.15 Hz) and respiratory-frequency (0.20 to 0.30 Hz) ranges with fast Fourier transform power spectra and used cross-spectral analysis to determine the phase relation between the two signals. As expected, cardiac pacing eliminated beat-to-beat RR interval variability. Against expectations, however, cardiac pacing in the supine position significantly reduced arterial pressure oscillations in the respiratory frequency (systolic, 6.8+/-1.8 to 2.9 +/-0.6 mm Hg2/Hz, P=.017). In contrast, cardiac pacing in the 40 degree tilt position increased arterial pressure variability (systolic, 8.0+/-1.8 to 10.8 +/-2.6, P=.027). Cross-spectral analysis showed that 40 degree tilt shifted the phase relation between systolic pressure and RR interval at the respiratory frequency from positive to negative (9 +/-7 degrees versus -17+/-11 degrees, P=.04); that is, in the supine position, RR interval changes appeared to lead arterial pressure changes, and in the upright position, RR interval changes appeared to follow arterial pressure changes. CONCLUSIONS: These results demonstrate that respiratory sinus arrhythmia can actually contribute to respiratory arterial

  15. 76 FR 78805 - Airworthiness Directives; Rolls-Royce plc (RR) RB211-Trent 800 Series Turbofan Engines

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-12-20

    ...-38-AD; Amendment 39-16898; AD 2011-26-08] RIN 2120-AA64 Airworthiness Directives; Rolls-Royce plc (RR...: Final rule. SUMMARY: We are adopting a new airworthiness directive (AD) for all Rolls-Royce plc (RR... developing this AD. We considered the comments received. Request To Correct Title in Rolls-Royce...

  16. Evaluation of the i3 Scale-up of Reading Recovery: Year One Report, 2011-12. RR-76

    ERIC Educational Resources Information Center

    May, Henry; Gray, Abigail; Gillespie, Jessica N.; Sirinides, Philip; Sam, Cecile; Goldsworthy, Heather; Armijo, Michael; Tognatta, Namrata

    2013-01-01

    Reading Recovery (RR) is a short-term early intervention designed to help the lowest-achieving readers in first grade reach average levels of classroom performance in literacy. Students identified to receive Reading Recovery meet individually with a specially trained Reading Recovery (RR) teacher every school day for 30-minute lessons over a…

  17. 78 FR 65758 - Receipt of Petition for Decision That Nonconforming 2011-2012 BMW S1000RR Motorcycles Are...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-11-01

    ... in the Federal Register published on April 11, 2000 (65 FR 19477-78). How to Read Comments Submitted...-2012 BMW S1000RR Motorcycles Are Eligible for Importation AGENCY: National Highway Traffic Safety... Traffic Safety Administration (NHTSA) of a petition for a decision that 2011-2012 BMW S1000RR...

  18. The Use of TaBoRR as a Heavy Oil Upgrader

    SciTech Connect

    Lee Brecher; Charles Mones

    2009-02-05

    Preliminary testing has shown that Western Research Institute's (WRI) Tank Bottom Recovery and Remediation (TaBoRR{reg_sign}) technology shows promise for heavy oil upgrading. Approximately 70 to 75 wt% of a Canadian Cold Lake bitumen feed was converted to a partially upgraded overhead product that could be transported directly by pipeline or blended with the parent bitumen to produce transportable crude. TaBoRR{reg_sign} was originally developed to remediate tank bottom wastes by producing a distillate product and solid waste. TaBoRR{reg_sign}'s processing steps include breaking a water-oil emulsion, recovering a light hydrocarbon fraction by distillation in a stripper unit, and pyrolyzing the residua reducing it to additional overhead and a benign coke for disposal. Cold Lake bitumen was tested in WRI's bench-scale equipment to evaluate the potential use of TaBoRR{reg_sign} technology for heavy oil upgrading to produce a stable, partially (or fully) upgraded product that will allow diluent-reduced or diluent-free transportation of bitumen or ultra-heavy crudes to market. Runs were conducted at temperatures of low, intermediate and high severity in the stripper to produce stripper overhead and bottoms. The bottoms from each of these runs were processed further in a 6-inch screw pyrolyzer to produce pyrolyzer overhead for blending with the corresponding stripper overheads. Proceeding in this fashion yielded three partially upgraded crudes. The products from TaBoRR{reg_sign} processing, the parent bitumen, and bitumen blends were subjected to stability and compatibility testing at the National Centre for Upgrading Technology (NCUT). Chemical analyses of the overhead product blends have met pipeline specifications for viscosity and density; however the bromine number does not, which might indicate the need for mild hydrotreating. Storage stability tests showed the blends to be stable. The blends were also soluble and compatible with most other Alberta crudes.

  19. Relationship between electrocardiographic RR and QT interval variabilities and indices of ventricular function in healthy subjects.

    PubMed

    Lewis, M J; Short, A L

    2008-01-01

    To date there has been no simultaneous characterization of the influence of physical exercise on cardiac ventricular function and cardiac electrical variability. Consequently, little is known about the relationship between the ventricular function and either heart rate (RR) or repolarization (QT) variability. In particular, the relationship between the QT variability index (QTVI) and ventricular function would be of clinical interest. Eight males of similar age (20.7 +/- 0.4 years (mean +/- SD)), mass (78.4 +/- 7.7 kg) and aerobic fitness (50.7 +/- 4.9 ml kg(-1) min(-1)) undertook progressive bicycle exercise. A three-lead Holter ECG was recorded continuously during pre-exercise, exercise and recovery, and mean values of RR and QT, their variabilities (RMSSD and SDNN) and their relative variability (QTVI) were determined. Traditional indices of ventricular function were determined beat to beat via impedance cardiography, and beat-to-beat blood pressure was recorded via photoplethysmography. Multiple linear regression analysis using the stepwise method resulted in significant models for each of the dependent variables (RR, QT, RR and QT variabilities, QTVI), using indices of the ventricular function as predictor variables. Notably, the QTVI reflected both the stroke volume index (SVI) and the acceleration index (ACI), which are measures of cardiac 'output' per contraction and the force of contraction, respectively. This relationship was largely unperturbed by physical exercise, in contrast with the results for all other dependent variables. We conclude that the QTVI is a reasonably consistent measure of the cardiac ventricular function, and as such is a more useful index than other parameters based on RR or QT interval alone. PMID:18175856

  20. Eclipses Observed by Large Yield RAdiometer (LYRA) - A Sensitive Tool to Test Models for the Solar Irradiance

    NASA Astrophysics Data System (ADS)

    Shapiro, A. I.; Schmutz, W.; Dominique, M.; Shapiro, A. V.

    2013-08-01

    We analyze the light curves of the recent solar eclipses measured by the Herzberg channel (200 - 220 nm) of the Large Yield RAdiometer (LYRA) onboard Project for OnBoard Autonomy (PROBA2). The measurements allow us to accurately retrieve the center-to-limb variations (CLV) of the solar brightness. The formation height of the radiation depends on the observing angle, so the examination of the CLV provide information about a broad range of heights in the solar atmosphere. We employ the 1D NLTE radiative transfer COde for Solar Irradiance (COSI) to model the measured light curves and corresponding CLV dependencies. The modeling is used to test and constrain the existing 1D models of the solar atmosphere, e.g. the temperature structure of the photosphere and the treatment of the pseudo-continuum opacities in the Herzberg continuum range. We show that COSI can accurately reproduce not only the irradiance from the entire solar disk, but also the measured CLV. Hence it can be used as a reliable tool for modeling the variability of the spectral solar irradiance.

  1. A study of the continuum flux and the line structure in the IUE spectrum of Beta Lyrae

    NASA Astrophysics Data System (ADS)

    Aydin, C.; Brandi, E.; Engin, S.; Ferrer, O. E.; Hack, M.; Sahade, J.; Solivella, G.; Yilmaz, N.

    1988-03-01

    A study of the available archival IUE images of Beta Lyrae has led to the following results: (1) for lambda in the range of 1250 - 1500 A, the eclipse depth at second conjunction is slightly larger than the eclipse depth at primary conjunction; they are equal at about 1670 A; (2) the profiles of the resonance lines of SiIV (and the same seems to be true for NV and CIV) can be described as composite, formed by the superposition of a stationary P Cygni profile that suggests a velocity of approach of -170 km/s and a broad, less strong, emission that seems to yield a velocity distribution in antiphase with the velocity curve of the B8 II component of the system; and (3) the emission lines of the intercombination doublet of semiforbidden N II at about 2140 A suggest a velocity of about -130 km/s. The interpretation of the latter composite profile appears similar to the one suggested by Sahade (1966) to describe H-alpha and He I 5876 and He I 6678, and by Batten and Sahade (1973) to describe H-alpha.

  2. A study of the continuum flux and the line structure in the IUE spectrum of Beta Lyrae

    NASA Technical Reports Server (NTRS)

    Aydin, C.; Engin, S.; Brandi, E.; Ferrer, O. E.; Hack, M.

    1988-01-01

    A study of the available archival IUE images of Beta Lyrae has led to the following results: (1) for lambda in the range of 1250 - 1500 A, the eclipse depth at second conjunction is slightly larger than the eclipse depth at primary conjunction; they are equal at about 1670 A; (2) the profiles of the resonance lines of SiIV (and the same seems to be true for NV and CIV) can be described as composite, formed by the superposition of a stationary P Cygni profile that suggests a velocity of approach of -170 km/s and a broad, less strong, emission that seems to yield a velocity distribution in antiphase with the velocity curve of the B8 II component of the system; and (3) the emission lines of the intercombination doublet of semiforbidden N II at about 2140 A suggest a velocity of about -130 km/s. The interpretation of the latter composite profile appears similar to the one suggested by Sahade (1966) to describe H-alpha and He I 5876 and He I 6678, and by Batten and Sahade (1973) to describe H-alpha.

  3. Distinct Signal Transduction Pathways Downstream of the (P)RR Revealed by Microarray and ChIP-chip Analyses

    PubMed Central

    Zaade, Daniela; Schmitz, Jennifer; Benke, Eileen; Klare, Sabrina; Seidel, Kerstin; Kirsch, Sebastian; Goldin-Lang, Petra; Zollmann, Frank S.; Unger, Thomas; Funke-Kaiser, Heiko

    2013-01-01

    The (pro)renin receptor ((P)RR) signaling is involved in different pathophysiologies ranging from cardiorenal end-organ damage via diabetic retinopathy to tumorigenesis. We have previously shown that the transcription factor promyelocytic leukemia zinc finger (PLZF) is an adaptor protein of the (P)RR. Furthermore, recent publications suggest that major functions of the (P)RR are mediated ligand-independently by its transmembrane and intracellular part, which acts as an accessory protein of V-ATPases. The transcriptome and recruitmentome downstream of the V-ATPase function and PLZF in the context of the (P)RR are currently unknown. Therefore, we performed a set of microarray and chromatin-immunoprecipitation (ChIP)-chip experiments using siRNA against the (P)RR, stable overexpression of PLZF, the PLZF translocation inhibitor genistein and the specific V-ATPase inhibitor bafilomycin to dissect transcriptional pathways downstream of the (P)RR. We were able to identify distinct and overlapping genetic signatures as well as novel real-time PCR-validated target genes of the different molecular functions of the (P)RR. Moreover, bioinformatic analyses of our data confirm the role of (P)RŔs signal transduction pathways in cardiovascular disease and tumorigenesis. PMID:23469216

  4. Intensive Observations of Cataclysmic, RR Lyr, and High Amplitude delta Scuti (HADS) Variable Stars

    NASA Astrophysics Data System (ADS)

    Hambsch, F.-J.

    2012-06-01

    An intensive observing campaign is ongoing to study cataclysmic, RR Lyr (with and without Blazhko effect), and High Amplitude delta Scuti (HADS) variable stars. These observations are based on requests and in collaboration with different organisations (CBA, VSNET, GEOS) and individuals. Observations are taken from my private observatories in Belgium, Chile, and through shared use of an observatory belonging to the AAVSOnet in New Mexico. Examples of individual stars intensively followed-up on are: CD Ind and BW Scl, two cataclysmic variables; NU Aur, an RR Lyr star with strong Blazhko effect; and GSC0762-0110, a HADS star. Many publications in different journals including Astronomy and Astrophysics have already emerged from this research.

  5. 3D τ RR -minimization in AdS4 gauged supergravity

    NASA Astrophysics Data System (ADS)

    Amariti, Antonio; Gnecchi, Alessandra

    2016-07-01

    In this paper we propose the identification in AdS4 N = 2 gauged supergravity of the coefficient τRR of 3D N = 2 SCFTs. We constrain the structure of this function in supergravity by combining the results from unitarity, holography and localization. We show that our conjectured function is minimized by the exact R-charge, corresponding to a gravitational attractor for the scalars of special geometry. We identify this mechanism with the supergravity dual of τ RR -minimization. We check this proposal in ABJM model, comparing with expectations from localization and AdS/CFT duality. We comment also on possible relations with black hole microstates counting, recently obtained from application of localization techniques.

  6. Gated current integrator for the beam in the RR barrier buckets

    SciTech Connect

    A. Cadorn; C. Bhat; J. Crisp

    2003-06-10

    At the Fermilab Recycler Ring (RR), the antiproton (pbar) beam will be stored azimuthally in different segments created by barrier buckets. The beam in each segment may have widely varying intensities. They have developed a gated integrator system to measure the beam intensity in each of the barrier bucket. Here they discuss the design of the system and the results of beam measurements using the integrator.

  7. Alignment of R-R interval signals using the circadian heart rate rhythm.

    PubMed

    Gayraud, Nathalie T H; Manis, George

    2015-01-01

    R-R interval signals that come from different subjects are regularly aligned and averaged according to the horological starting time of the recordings. We argue that the horological time is a faulty alignment criterion and provide evidence in the form of a new alignment method. Our main motivation is that the human heart rate (HR) rhythm follows a circadian cycle, whose pattern can vary among different classes of people. We propose two novel alignment algorithms that consider the HR circadian rhythm, the Puzzle Piece Alignment Algorithm (PPA) and the Event Based Alignment Algorithm (EBA). First, we convert the R-R interval signal into a series of time windows and compute the mean HR per window. Then our algorithms search for matching circadian patterns to align the signals. We conduct experiments using R-R interval signals extracted from two databases in the Physionet Data Bank. Both algorithms are able to align the signals with respect to the circadian rhythmicity of HR. Furthermore, our findings confirm the presence of more than one pattern in the circadian HR rhythm. We suggest an automatic classification of signals according to the three most prominent patterns. PMID:26737009

  8. Contributions of tidal lung inflation to human R-R interval and arterial pressure fluctuations

    NASA Technical Reports Server (NTRS)

    Koh, J.; Brown, T. E.; Beightol, L. A.; Eckberg, D. L.

    1998-01-01

    We studied the effects of mechanical lung inflation on respiratory frequency R-R interval and arterial pressure fluctuations in nine healthy young adults undergoing elective orthopedic surgery. We conducted this research to define the contribution of pulmonary and thoracic stretch receptor input to respiratory sinus arrhythmia. We compared fast Fourier transform spectral power during three modes of ventilation: (1) spontaneous, frequency-controlled (0.25 Hz) breathing, (2) intermittent positive pressure ventilation (0.25 Hz, with a tidal volume of 8 ml/kg) and (3) high frequency jet ventilation (5.0 Hz, 2.5 kg/cm2), after sedation and vecuronium paralysis. Mean R-R intervals, arterial pressures and arterial blood gas levels were comparable during all three breathing conditions. Respiratory frequency systolic pressure spectral power was comparable during spontaneous breathing and conventional mechanical ventilation, but was significantly reduced during high frequency jet ventilation (P < 0.05). Respiratory frequency R-R interval spectral power (used as an index of respiratory sinus arrhythmia) declined dramatically with sedation and muscle paralysis (P < 0.05), but was greater during conventional mechanical, than high frequency jet ventilation (P < 0.05). These results suggest that although phasic inputs from pulmonary and thoracic stretch receptors make a statistically significant contribution to respiratory sinus arrhythmia, that contribution is small.

  9. 76 FR 59013 - Airworthiness Directives; Rolls-Royce plc (RR) RB211-Trent 800 Series Turbofan Engines

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-09-23

    ...-30-AD; Amendment 39-16657; AD 2011-08-07] RIN 2120-AA64 Airworthiness Directives; Rolls-Royce plc (RR... . SUPPLEMENTARY INFORMATION: Airworthiness Directive 2011-08-07, Amendment 39-16657 (76 FR 24798, May 3,...

  10. 76 FR 40217 - Airworthiness Directives; Rolls-Royce plc (RR) RB211-524 Series Turbofan Engines

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-07-08

    ...; AD 2011-13-01] RIN 2120-AA64 Airworthiness Directives; Rolls-Royce plc (RR) RB211-524 Series Turbofan... Service Information Rolls-Royce has issued RR Alert Service Bulletin RB.211-78-AG084, Revision 5, dated..., 44701. Sec. 39.13 0 2. The FAA amends Sec. 39.13 by adding the following new AD: 2011-13-01...

  11. [PAIN MANAGEMENT IN PATIENTS OF RAPID RECOVERY (RR) PROGRAM IN TOTAL KNEE ARTHROPLASTY (TKA)].

    PubMed

    Marina Fernández, Rosa; Ginés Mateos, Gracia; Arco Pérez, Ma Carmen; Nuevo Gayoso, Montse; Faura Vendrell, Teresa

    2015-06-01

    Total knee arthroplasty (TKA) is a surgery consisting on the artificial joint replacement, due to a traumatic injury or a degenerative process or arthrosis. This surgery causes an important pain to patients, and sometimes affects negatively on their recovery. The choice of the prostheses will depend on the anatomical features of the patient and the surgeon criterion. The concept of a "rapid recovery surgery" was introduced in 1997 by Khelet and meant the beginning of the Fast Track model or the Rapid Recovery (RR) linked to an accelerated rehabilitation, an early discharge and the optimization of all the aspects of pre, intra and post-operative patient experience. Fast recovery is a surgical process which aims to achieve maximum autonomy of the patient through education, pain control and early mobilization. The key of the rapid recovery is to get the involvement of the patient thanks to the empowerment, which means a preoperative patient education that will help to reduce anxiety and it will make easier to engage in their own recovery. Furthermore the patient will take part of an effective post-operative physical therapy, using all the necessary tools to increase their ability to manage their own health problems. The empowerment of these patients is part of the Nursing Model in the Hospital Clinic de Barcelona (HCB), adopted by the Nursing Management in December of 2012. In Catalonia, until the start of the RR surgery, 14,132 interventions in 2008 where done by TKA conventional surgery, needing subsequent conventional hospitalization. This article describes the care and outcomes of nurse interventions, defined in the RR of TKA clinical way, which is focused on the pain's minimization and the impact on patients' mobilization. It was performed in a monographic unit from a tertiary-level hospital in Barcelona in 2013. PMID:26591937

  12. Enhanced production of (R,R)-2,3-butanediol by metabolically engineered Klebsiella oxytoca.

    PubMed

    Park, Jong Myoung; Rathnasingh, Chelladurai; Song, Hyohak

    2015-10-01

    Microbial fermentation produces a racemic mixture of 2,3-butanediol ((R,R)-BD, (S,S)-BD, and meso-BD), and the compositions and physiochemical properties vary from microorganism to microorganism. Although the meso form is much more difficult to transport and store because of its higher freezing point than those of the optically active forms, most microorganisms capable of producing 2,3-BD mainly yield meso-2,3-BD. Thus, we developed a metabolically engineered (R,R)-2,3-BD overproducing strain using a Klebsiella oxytoca ΔldhA ΔpflB strain, which shows an outstanding 2,3-BD production performance with more than 90 % of the meso form. A budC gene encoding 2,3-BD dehydrogenase in the K. oxytoca ΔldhA ΔpflB strain was replaced with an exogenous gene encoding (R,R)-2,3-BD dehydrogenase from Paenibacillus polymyxa (K. oxytoca ΔldhA ΔpflB ΔbudC::PBDH strain), and then its expression level was further amplified with using a pBBR1MCS plasmid. The fed-batch fermentation of the K. oxytoca ΔldhA ΔpflB ΔbudC::PBDH (pBBR-PBDH) strain with intermittent glucose feeding allowed the production of 106.7 g/L of (R,R)-2,3-BD [meso-2,3-BD, 9.3 g/L], with a yield of 0.40 g/g and a productivity of 3.1 g/L/h, which should be useful for the industrial application of 2,3-BD. PMID:26275527

  13. Automatic home care system for monitoring HR/RR during sleep.

    PubMed

    Zhu, Xin; Chen, Wenxi; Tang, Zunyi; Nemoto, Tetsu; Wei, Daming

    2008-01-01

    This paper described an automatic home care system for monitoring HR/RR during sleep. Pressure signal is measured with a completely unconstrained pressure sensor beneath a pillow; then the signal is digitalized and the data are transmitted to a remote server using TCP/IP via a netbox. The data are processed and analyzed with a wavelet-based algorithm to obtain the heart rate and respiration rhythm during sleep. Through analyzing 180 days' data obtained from a female subject, it was found that this system can be used for daily monitoring heart rate and respiration rhythm during sleep and evaluating the quality of sleep at home. PMID:19162708

  14. Automatic identification of fetal breathing movements in fetal RR interval time series.

    PubMed

    Van Leeuwen, Peter; Voss, Anna; Cysarz, Dirk; Edelhäuser, Friedrich; Grönemeyer, Dietrich

    2012-03-01

    Fetal breathing movements are associated with respiratory sinus arrhythmia (RSA). We present an algorithm which processes RR interval time series in the time and frequency domain, identifying spectral peaks with characteristics consistent with fetal RSA. Tested on 50 data sets from the second and third trimester, the algorithm had a sensitivity of 96.1%, false positive rate 35.7%, false negative rate 3.9%. The characteristics of automatically and visually identified episodes were very similar and corresponded the expected changes over gestation. The method is suited for easy and reliable identification of fetal breathing movements. PMID:21621759

  15. RR interval variability during galvanic vestibular stimulation correlates with arterial pressure upon head-up tilt.

    PubMed

    Tanaka, Kunihiko; Ito, Yamato; Ikeda, Mayumi; Katafuchi, Tetsuro

    2014-10-01

    RR interval variability (RRIV) in the supine position without and with galvanic vestibular stimulation (GVS (off) and GVS (on), respectively), changes in mean arterial pressure (MAP) at the onset of 60° head-up tilt (HUT) during GVS (off), and their relationship were analyzed in 25 healthy young subjects. MAP decreased by less than 5mmHg or increased upon HUT in 12 subjects (UP), but MAP decreased by more than 5mmHg in 13 subjects (DOWN). Applying sinusoidal GVS of 2mA at a random frequency of 0.2 to 10.0Hz did not change the RR intervals or MAP. However, the high frequency component (HF) of RRIV increased in both UP and DOWN subjects. The increase in DOWN subjects was larger than that in UP subjects. The ratio of the low frequency component to HF (L/H) increased in UP subjects during GVS (on), but did not reach a significant level in DOWN subjects. The changes in the HF were significantly correlated with changes in MAP at the onset of HUT; i.e., the subjects with larger increases in the HF during GVS (on) showed larger decreases in MAP. Thus, GVS or vestibular input during HUT possibly activates the vagal nerves, and the dominance of excitation in sympathetic or vagal nerves during vestibular stimulation is important for controlling MAP at the onset of HUT. PMID:24783995

  16. On RR couplings, singularity structures and all order α' contact interactions to BPS string amplitudes

    NASA Astrophysics Data System (ADS)

    Hatefi, Ehsan

    2015-12-01

    We evaluate five point world-sheet string theory amplitudes of one transverse scalar field, two world volume gauge fields (and two transverse scalars, a gauge field) in the presence of a closed string Ramond-Ramond vertex operator in its symmetric picture. We carry out all the entire S-matrix elements of five point mixed RR-scalars/gauge fields < C -1 ϕ 0 A -1 A 0>, < C -1 ϕ -1 A 0 A 0>, < C -1 A 0 ϕ -1 ϕ 0> and < C -1 A -1 ϕ 0 ϕ 0> in detail and start comparing all order α' contact interactions and singularities in both transverse and world volume directions. We explore the presence of various new couplings in string theory effective actions and find out their all order α' higher derivative corrections in both type IIA and IIB. Ultimately we make various remarks for the singularities and contact terms whose RR momenta are embedded in transverse directions. α' corrections to some of Myers terms are also addressed.

  17. A preprocessing tool for removing artifact from cardiac RR interval recordings using three-dimensional spatial distribution mapping.

    PubMed

    Stapelberg, Nicolas J C; Neumann, David L; Shum, David H K; McConnell, Harry; Hamilton-Craig, Ian

    2016-04-01

    Artifact is common in cardiac RR interval data that is recorded for heart rate variability (HRV) analysis. A novel algorithm for artifact detection and interpolation in RR interval data is described. It is based on spatial distribution mapping of RR interval magnitude and relationships to adjacent values in three dimensions. The characteristics of normal physiological RR intervals and artifact intervals were established using 24-h recordings from 20 technician-assessed human cardiac recordings. The algorithm was incorporated into a preprocessing tool and validated using 30 artificial RR (ARR) interval data files, to which known quantities of artifact (0.5%, 1%, 2%, 3%, 5%, 7%, 10%) were added. The impact of preprocessing ARR files with 1% added artifact was also assessed using 10 time domain and frequency domain HRV metrics. The preprocessing tool was also used to preprocess 69 24-h human cardiac recordings. The tool was able to remove artifact from technician-assessed human cardiac recordings (sensitivity 0.84, SD = 0.09, specificity of 1.00, SD = 0.01) and artificial data files. The removal of artifact had a low impact on time domain and frequency domain HRV metrics (ranging from 0% to 2.5% change in values). This novel preprocessing tool can be used with human 24-h cardiac recordings to remove artifact while minimally affecting physiological data and therefore having a low impact on HRV measures of that data. PMID:26751605

  18. Relationship between the Initial Systolic Time Interval and RR-interval during an exercise stimulus measured with Impedance Cardiography

    NASA Astrophysics Data System (ADS)

    Hoekstra, Femke; Habers, Esther; Janssen, Thomas W. J.; Verdaasdonk, Rudolf M.; Meijer, Jan H.

    2010-04-01

    The Initial Systolic Time Interval (ISTI), obtained from the electrocardiogram and impedance cardiogram, is considered to be a measure for the time delay between the electrical and mechanical activity of the heart and reflects an active period of the heart cycle. The relationship between ISTI and the total heart cycle (RR-interval) was studied in three groups of young, healthy volunteers: low, moderately and highly trained subjects. The three groups were exposed to an exercise stimulus on a cycle ergometer with an increasing work load to increase the heart rate. ISTI was decreased with decreasing RR-interval. However, the relative proportion of ISTI, ISTI/RR, was found to increase with decreasing RR-interval. This relationship was found to be inversely proportional. The rate of this increase in ISTI/RR was significantly higher in highly trained subjects. Also, over the whole range of heart rates ISTI was longer in these subjects. It is concluded that ISTI can be used to evaluate cardiac performance during physical exercise non-invasively and in an extramural setting.

  19. Controlled Pd(0)/t Bu3P Catalyzed Suzuki Cross-Coupling Polymerization of AB-Type Monomers with ArPd(t Bu3P)X or Pd2(dba)3/t Bu3P/ArX as the Initiator

    SciTech Connect

    Zhang, Honghai; Xing, Chun-Hui; Hu, Qiao-Sheng; Hong, Kunlun

    2015-02-05

    The synthesis of well-defined and functionalized conjugated polymers, which are essential in the development of efficient organic electronics, through Suzuki cross-coupling polymerizations has been a challenging task. We developed controlled Pd(0)/t-Bu3P-catalyzed Suzuki cross-coupling polymerizations of AB-type monomers via the chain-growth mechanism with a series of in situ generated ArPd(t-Bu3P)X (X = I, Br, Cl) complexes as initiators. Among them, the combinations of Pd2(dba)3/t-Bu3P/p-BrC6H4I, Pd2(dba)3/t-Bu3P/p-BrC6H4CH2OH and Pd2(dba)3/t-Bu3P/p-PhCOC6H4Br were identified as highly robust initiator systems, resulting in polymers with predictable molecular weight and narrow polydispersity (PDI~1.13-1.20). In addition, Pd2(dba)3/t-Bu3P/p-BrC6H4CH2OH and Pd2(dba)3/t-Bu3P/p-PhCOC6H4Br initiator systems afforded functional polymers with >95% fidelity. Our results paved the road to access well-defined conjugated polymers, including conjugated polymers with complex polymer architectures such as block copolymers and branch copolymers.

  20. Controlled Pd(0)/t Bu3P Catalyzed Suzuki Cross-Coupling Polymerization of AB-Type Monomers with ArPd(t Bu3P)X or Pd2(dba)3/t Bu3P/ArX as the Initiator

    DOE PAGESBeta

    Zhang, Honghai; Xing, Chun-Hui; Hu, Qiao-Sheng; Hong, Kunlun

    2015-02-05

    The synthesis of well-defined and functionalized conjugated polymers, which are essential in the development of efficient organic electronics, through Suzuki cross-coupling polymerizations has been a challenging task. We developed controlled Pd(0)/t-Bu3P-catalyzed Suzuki cross-coupling polymerizations of AB-type monomers via the chain-growth mechanism with a series of in situ generated ArPd(t-Bu3P)X (X = I, Br, Cl) complexes as initiators. Among them, the combinations of Pd2(dba)3/t-Bu3P/p-BrC6H4I, Pd2(dba)3/t-Bu3P/p-BrC6H4CH2OH and Pd2(dba)3/t-Bu3P/p-PhCOC6H4Br were identified as highly robust initiator systems, resulting in polymers with predictable molecular weight and narrow polydispersity (PDI~1.13-1.20). In addition, Pd2(dba)3/t-Bu3P/p-BrC6H4CH2OH and Pd2(dba)3/t-Bu3P/p-PhCOC6H4Br initiator systems afforded functional polymers with >95% fidelity. Our results pavedmore » the road to access well-defined conjugated polymers, including conjugated polymers with complex polymer architectures such as block copolymers and branch copolymers.« less

  1. Tribolium castaneum RR-1 cuticular protein TcCPR4 is required for formation of pore canals in rigid cuticle.

    PubMed

    Noh, Mi Young; Muthukrishnan, Subbaratnam; Kramer, Karl J; Arakane, Yasuyuki

    2015-02-01

    Insect cuticle is composed mainly of structural proteins and the polysaccharide chitin. The CPR family is the largest family of cuticle proteins (CPs), which can be further divided into three subgroups based on the presence of one of the three presumptive chitin-binding sequence motifs denoted as Rebers-Riddiford (R&R) consensus sequence motifs RR-1, RR-2 and RR-3. The TcCPR27 protein containing the RR-2 motif is one of the most abundant CPs present both in the horizontal laminae and in vertical pore canals in the procuticle of rigid cuticle found in the elytron of the red flour beetle, Tribolium castaneum. Depletion of TcCPR27 by RNA interference (RNAi) causes both unorganized laminae and pore canals, resulting in malformation and weakening of the elytron. In this study, we investigated the function(s) of another CP, TcCPR4, which contains the RR-1 motif and is easily extractable from elytra after RNAi to deplete the level of TcCPR27. Transcript levels of the TcCPR4 gene are dramatically increased in 3 d-old pupae when adult cuticle synthesis begins. Immunohistochemical studies revealed that TcCPR4 protein is present in the rigid cuticles of the dorsal elytron, ventral abdomen and leg but not in the flexible cuticles of the hindwing and dorsal abdomen of adult T. castaneum. Immunogold labeling and transmission electron microscopic analyses revealed that TcCPR4 is predominantly localized in pore canals and regions around the apical plasma membrane protrusions into the procuticle of rigid adult cuticles. RNAi for TcCPR4 resulted in an abnormal shape of the pore canals with amorphous pore canal fibers (PCFs) in their lumen. These results support the hypothesis that TcCPR4 is required for achieving proper morphology of the vertical pore canals and PCFs that contribute to the assembly of a cuticle that is both lightweight and rigid. PMID:25664770

  2. Tribolium castaneum RR-1 Cuticular Protein TcCPR4 Is Required for Formation of Pore Canals in Rigid Cuticle

    PubMed Central

    Noh, Mi Young; Muthukrishnan, Subbaratnam; Kramer, Karl J.; Arakane, Yasuyuki

    2015-01-01

    Insect cuticle is composed mainly of structural proteins and the polysaccharide chitin. The CPR family is the largest family of cuticle proteins (CPs), which can be further divided into three subgroups based on the presence of one of the three presumptive chitin-binding sequence motifs denoted as Rebers-Riddiford (R&R) consensus sequence motifs RR-1, RR-2 and RR-3. The TcCPR27 protein containing the RR-2 motif is one of the most abundant CPs present both in the horizontal laminae and in vertical pore canals in the procuticle of rigid cuticle found in the elytron of the red flour beetle, Tribolium castaneum. Depletion of TcCPR27 by RNA interference (RNAi) causes both unorganized laminae and pore canals, resulting in malformation and weakening of the elytron. In this study, we investigated the function(s) of another CP, TcCPR4, which contains the RR-1 motif and is easily extractable from elytra after RNAi to deplete the level of TcCPR27. Transcript levels of the TcCPR4 gene are dramatically increased in 3 d-old pupae when adult cuticle synthesis begins. Immunohistochemical studies revealed that TcCPR4 protein is present in the rigid cuticles of the dorsal elytron, ventral abdomen and leg but not in the flexible cuticles of the hindwing and dorsal abdomen of adult T. castaneum. Immunogold labeling and transmission electron microscopic analyses revealed that TcCPR4 is predominantly localized in pore canals and regions around the apical plasma membrane protrusions into the procuticle of rigid adult cuticles. RNAi for TcCPR4 resulted in an abnormal shape of the pore canals with amorphous pore canal fibers (PCFs) in their lumen. These results support the hypothesis that TcCPR4 is required for achieving proper morphology of the vertical pore canals and PCFs that contribute to the assembly of a cuticle that is both lightweight and rigid. PMID:25664770

  3. Effects of particle characteristics on performance of RR5K PETN

    SciTech Connect

    Rogers, J.W. Jr.; Duncan, A.A.

    1982-06-01

    A particle characterization of production lots of RR5K PETN has been completed. Prediction models were derived which identify those particle characteristics which influence sensitivity and performance. Those factors which have a positive influence on threshold burst current were also found to have a positive influence on transit time. The models may be useful in screening new lots of PETN prior to test firing. In general, large distributions of shapes and sizes, with the larger particles being needle-like or elongated, lead to low threshold burst currents and short transit times. The threshold burst current was also found to be inversely proportional to the temperature at which the units were test fired.

  4. The infrared variability and nature of symbiotic stars. II - RR Tel

    NASA Astrophysics Data System (ADS)

    Feast, M. W.; Whitelock, P. A.; Catchpole, R. M.; Roberts, G.; Carter, B. S.

    1983-03-01

    The presence of a cool Mira-like component having a period of 387 days is established for the very slow nova symbiotic system RR Tel in the 1972-1981 period, using JHKL IR photometry. Single star models for the system are suggested to be unlikely in view of evidence for a similar periodicity in the photographic region prior to the 1944 outburst. These results are consistent with the presence of a constant period and mean luminosity Mira at all times. If the Mira component is normal, then the IR excess increases toward Mira minimum and may be interpreted as a partial heating of the dust by the blue component and/or ionized gas in the system. The evidence indicates that all slow novae contain cool giant or supergiant components, so that the systems must be of great physical size.

  5. Plutonium residue recovery (PuRR) project: Quarterly progress report, October--December 1988

    SciTech Connect

    Alire, R.M.; Coops, M.S.; Gregg, D.W.; Hickman, R.G.; Landrum, J.H.; Pittenger, L.C.; Johnson, G.K.; Johnson, I.; Mulcahey, T.P.; Piece, R.D.

    1989-02-01

    Substantial progress was made in several areas of the PuRR (plutonium residue recovery) program during the quarter. Criteria were developed for selecting process options, with the goal of process simplification. A modified flowsheet and material balance were selected that reflect these priorities. Efforts to effect a front-end separation by sedimentation were not successful. Experimental liquid-liquid extractions from alloys to salts based on valence change were performed. Results ranged from fair to good, but experimental equipment materials problems occurred. Also, substantial interference from the large excess of tramp metals present, which influence plutonium activity, suggested alternate approaches should be given priority. Estimates of the high-temperature thermodynamic functions of americium chlorides were calculated for the first time. 11 refs., 3 figs., 10 tabs.

  6. Using complexity metrics with R-R intervals and BPM heart rate measures

    PubMed Central

    Wallot, Sebastian; Fusaroli, Riccardo; Tylén, Kristian; Jegindø, Else-Marie

    2013-01-01

    Lately, growing attention in the health sciences has been paid to the dynamics of heart rate as indicator of impending failures and for prognoses. Likewise, in social and cognitive sciences, heart rate is increasingly employed as a measure of arousal, emotional engagement and as a marker of interpersonal coordination. However, there is no consensus about which measurements and analytical tools are most appropriate in mapping the temporal dynamics of heart rate and quite different metrics are reported in the literature. As complexity metrics of heart rate variability depend critically on variability of the data, different choices regarding the kind of measures can have a substantial impact on the results. In this article we compare linear and non-linear statistics on two prominent types of heart beat data, beat-to-beat intervals (R-R interval) and beats-per-min (BPM). As a proof-of-concept, we employ a simple rest-exercise-rest task and show that non-linear statistics—fractal (DFA) and recurrence (RQA) analyses—reveal information about heart beat activity above and beyond the simple level of heart rate. Non-linear statistics unveil sustained post-exercise effects on heart rate dynamics, but their power to do so critically depends on the type data that is employed: While R-R intervals are very susceptible to non-linear analyses, the success of non-linear methods for BPM data critically depends on their construction. Generally, “oversampled” BPM time-series can be recommended as they retain most of the information about non-linear aspects of heart beat dynamics. PMID:23964244

  7. Transgenic Overexpression of Aryl Hydrocarbon Receptor Repressor (AhRR) and AhR-Mediated Induction of CYP1A1, Cytokines, and Acute Toxicity

    PubMed Central

    Vogel, Christoph F.A.; Chang, W.L. William; Kado, Sarah; McCulloh, Kelly; Vogel, Helena; Wu, Dalei; Haarmann-Stemmann, Thomas; Yang, GuoXiang; Leung, Patrick S.C.; Matsumura, Fumio; Gershwin, M. Eric

    2016-01-01

    Background: The aryl hydrocarbon receptor repressor (AhRR) is known to repress aryl hydrocarbon receptor (AhR) signaling, but very little is known regarding the role of the AhRR in vivo. Objective: This study tested the role of AhRR in vivo in AhRR overexpressing mice on molecular and toxic end points mediated through a prototypical AhR ligand. Methods: We generated AhRR-transgenic mice (AhRR Tg) based on the genetic background of C57BL/6J wild type (wt) mice. We tested the effect of the prototypical AhR ligand 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) on the expression of cytochrome P450 (CYP)1A1 and cytokines in various tissues of mice. We next analyzed the infiltration of immune cells in adipose tissue of mice after treatment with TCDD using flow cytometry. Results: AhRR Tg mice express significantly higher levels of AhRR compared to wt mice. Activation of AhR by TCDD caused a significant increase of the inflammatory cytokines Interleukin (IL)-1β, IL-6 and IL-10, and CXCL chemokines in white epididymal adipose tissue from both wt and AhRR Tg mice. However, the expression of IL-1β, CXCL2 and CXCL3 were significantly lower in AhRR Tg versus wt mice following TCDD treatment. Exposure to TCDD caused a rapid accumulation of neutrophils and macrophages in white adipose tissue of wt and AhRR Tg mice. Furthermore we found that male AhRR Tg mice were protected from high-dose TCDD-induced lethality associated with a reduced inflammatory response and liver damage as indicated by lower levels of TCDD-induced alanine aminotransferase and hepatic triglycerides. Females from both wt and AhRR Tg mice were less sensitive than male mice to acute toxicity induced by TCDD. Conclusion: In conclusion, the current study identifies AhRR as a previously uncharacterized regulator of specific inflammatory cytokines, which may protect from acute toxicity induced by TCDD. Citation: Vogel CF, Chang WL, Kado S, McCulloh K, Vogel H, Wu D, Haarmann-Stemmann T, Yang GX, Leung PS, Matsumura F

  8. 77 FR 10355 - Airworthiness Directives; Rolls-Royce plc (RR) RB211-Trent 800 Series Turbofan Engines

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-02-22

    ... (68 FR 49344, August 18, 2003) and adding the following new AD: 2012-04-01 Rolls-Royce plc: Amendment... (68 FR 49344, August 18, 2003). (c) Applicability This AD applies to Rolls-Royce plc (RR) RB211-Trent...-12-AD; Amendment 39-16956; AD 2012-04-01] RIN 2120-AA64 Airworthiness Directives; Rolls-Royce plc...

  9. 76 FR 30529 - Airworthiness Directives; Rolls-Royce plc (RR) RB211-535 Series Turbofan Engines

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-05-26

    ...-39-AD; Amendment 39-16707; AD 2011-11-08] RIN 2120-AA64 Airworthiness Directives; Rolls-Royce plc (RR... considered the comments received. Request To Change Related Information Paragraph One commenter, Rolls-Royce plc asked us to use a different statement for Rolls-Royce contact information in paragraph (i) of...

  10. "D.L.&W. R.R. New Bergen Tunnel...Detail of Portal Masonry..." Plan Sheet. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    "D.L.&W. R.R. New Bergen Tunnel...Detail of Portal Masonry..." Plan Sheet. Revised December 22, 1906. On file at New Jersey Transit Corporation Headquarters, Newark, New Jersey - Delaware, Lackawanna & Western Railroad, South Bergen Tunnel, Jersey City, Hudson County, NJ

  11. "D.L.&W. R.R. New Bergen Tunnel...Details of Shaft..." Plan Sheet. October ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    "D.L.&W. R.R. New Bergen Tunnel...Details of Shaft..." Plan Sheet. October 30, 1908. On file at New Jersey Transit Corporation Headquarters, Newark, New Jersey - Delaware, Lackawanna & Western Railroad, South Bergen Tunnel, Jersey City, Hudson County, NJ

  12. "D.L.&W. R.R. New Bergen Tunnel...Detail of Open Cut Masonry..." Plan ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    "D.L.&W. R.R. New Bergen Tunnel...Detail of Open Cut Masonry..." Plan Sheet. Revised December 22, 1906. On file at New Jersey Transit Corporation Headquarters, Newark, New Jersey - Delaware, Lackawanna & Western Railroad, South Bergen Tunnel, Jersey City, Hudson County, NJ

  13. 76 FR 68663 - Airworthiness Directives; Rolls-Royce plc (RR) RB211-Trent 800 Series Turbofan Engines

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-11-07

    ... published in the Federal Register on August 3, 2010 (75 FR 45560). That NPRM would have revised the TLM of... the previous NPRM (75 FR 45560, August 3, 2010), RR requested that we supersede existing AD 2003-16-18, Amendment 39-13271 (68 FR 49344, August 18, 2003). That AD currently requires a life limit for...

  14. Transposon-mediated chromosomal rearrangements and gene duplications in the formation of the maize R-r complex.

    PubMed Central

    Walker, E L; Robbins, T P; Bureau, T E; Kermicle, J; Dellaporta, S L

    1995-01-01

    R-r controls the production of anthocyanin pigment in plant parts and the aleurone layer of seeds through the production of a family of related transcriptional activating proteins of the helix-loop-helix type. The R-r complex comprises a series of repeated, homologous components arranged in both direct and inverted orientations. These include the P component, a simple R gene that confers pigmentation of plant parts, and the S subcomplex that consists of a truncated inactive R gene called q, and two functional R genes, S1 and S2, that pigment the aleurone. The S genes are arranged in an unusual inverted head-to-head orientation. The identity of each functional component was confirmed by microprojectile bombardment of intact maize tissues with cloned genomic DNA and by analysis of in vivo mRNA populations. Sequence analysis suggests that the S subcomplex was derived through the rearrangement of a simple P-like progenitor element. At the rearrangement breakpoints, features typical of the CACTA family of transposable elements were found. The location and arrangement of these CACTA element sequences implies that this element may have mediated the chromosomal rearrangements that led to the formation of the R-r complex. The unusual structure of R-r explains much of the meiotic instability of the complex. Images PMID:7774593

  15. Detection and significance of a discrete very low frequency rhythm in RR interval variability in chronic congestive heart failure.

    PubMed

    Ponikowski, P; Chua, T P; Amadi, A A; Piepoli, M; Harrington, D; Volterrani, M; Colombo, R; Mazzuero, G; Giordano, A; Coats, A J

    1996-06-15

    Although in advanced chronic congestive heart failure (CHF) very low frequency (< 0.04 Hz, VLF) oscillations are prominent, the clinical importance and the physiologic basis of these rhythms have not been elucidated. To investigate the physiologic determinants of the VLF rhythms in RR interval variability, we studied 36 patients with stable, moderate to severe CHF (33 men, age: 58 +/- 8 years, ejection fraction 25 +/- 10%, peak oxygen consumption 18.1 +/- 4.6 ml/kg/min) and 12 age- and sex-matched controls using autoregressive spectral analysis of RR interval, blood pressure, and respiratory signals during controlled conditions. We quantified low frequency (LF) (0.04 to 0.15 Hz), high frequency (HF) (0.15 to 0.40 Hz), VLF, and total power (0 to 0.5 Hz), and calculated the coherence between systolic blood pressure and RR interval variability within each band. Peripheral chemosensitivity was assessed by the ventilatory response to hypoxia using transient inhalation of pure nitrogen. The influence of transient inactivation of peripheral chemoreceptors on the VLF rhythm was investigated by exposing 6 patients to hyperoxic (60% oxygen) conditions for 20 minutes. Twenty-three patients (64%) with CHF, but no controls, had a discrete VLF rhythm (0.019 +/- 0.008 Hz) in RR variability. The presence of VLF rhythm was not related to any difference in clinical parameters (etiology, New York Heart Association class, ejection fraction, oxygen uptake) but rather to a different pattern in RR interval and blood pressure variability: lower LF power (2.8 +/- 1.6 ms2 natural logarithm [ln]) compared either to patients without VLF (4.0 +/- 1.3 ms2 ln) or to controls (5.9 +/- 0.7 ms2 ln), higher percentage of power within VLF band (86.3 +/- 8.3% vs 77.5 +/- 7.9% and 61.5 +/- 14.1%) and a markedly impaired coherence between RR interval and systolic blood pressure variability within the LF band (0.26 +/- 0.10 vs 0.42 +/- 0.18 and 0.63 +/- 0.15, in patients with vs without VLF peak and

  16. Accretion and activity on the post-common-envelope binary RR Caeli

    NASA Astrophysics Data System (ADS)

    Ribeiro, T.; Baptista, R.; Kafka, S.; Dufour, P.; Gianninas, A.; Fontaine, G.

    2013-08-01

    Context. Current scenarios for the evolution of interacting close binaries - such as cataclysmic variables (CVs) - rely mainly on our understanding of low-mass star angular momentum loss (AML) mechanisms. The coupling of stellar wind with its magnetic field, i.e., magnetic braking, is the most promising mechanism believed to drive AML in these stars. There are basically two properties thought to drive magnetic braking: the stellar magnetic field and the stellar wind. Understanding the mechanisms that drive AML therefore requires a comprehensive understanding of these two properties as well. Aims. RR Cae is a well-known nearby (d = 20 pc) eclipsing DA+M binary with an orbital period of P = 7.29 h. The system harbors a metal-rich cool DA white dwarf (WD) and a highly active M-dwarf locked in synchronous rotation. The metallicity of the WD suggests that wind accretion is taking place, which provides a good opportunity to obtain the mass-loss rate of the M-dwarf component. We aim to reach a better understanding of the AML mechanisms in close binaries by characterizing the relevant properties of the M-dwarf component of this system. Methods. We analyzed multi-epoch time-resolved high-resolution spectra of RR Cae in search for traces of magnetic activity and accretion. We selected a number of well-known chromospheric activity indicators and studied their phase-dependence and long-term behavior. Indirect-imaging tomographic techniques were also applied to provide the surface brightness distribution of the magnetically active M-dwarf. The blue part of the spectrum was modeled using a state-of-the-art atmosphere model to constrain the WD properties and its metal enrichment. The latter was used to improve the determination of the mass-accretion rate from the M-dwarf wind. Results. Doppler imaging of the M-dwarf component of RR Cae reveals a polar feature similar to those observed in fast-rotating solar-type stars. Analysis of tomographic reconstruction of the Hα emission

  17. Modelling of dust around the symbiotic Mira RR Telescopii during obscuration epochs

    NASA Astrophysics Data System (ADS)

    Jurkic, T.; Kotnik-Karuza, D.

    2012-08-01

    Context. Symbiotic Miras represent a class of peculiar binaries whose nature is still not well understood. Physical properties of the circumstellar dust and associated physical mechanisms play an important role in understanding the evolution of symbiotic binaries and the interaction between their components. We present a model of inner dust regions around the cool Mira component of the symbiotic nova RR Tel based on the near-IR terrestrial photometry and infrared ISO spectra. Aims: Our goal is to find a comprehensive and consistent model of the circumstellar inner dust regions around the Mira component that can explain the observed photometric and spectroscopic features in the near- and mid-infrared. Methods: Available JHKL photometric observations from South African Astronomical Observatory were collected and corrected for Mira pulsations as well as for interstellar reddening to follow temporal changes of the near-infrared colours. Spectral energy distributions (SEDs) from 1 to 13 μm during obscuration epoch were reconstructed with the simultaneously available ISO/SWS spectra and JHKL magnitudes. The dust properties were determined by modelling both the reconstructed SEDs and the near-IR colours using the DUSTY numerical code. This 1D code solves radiative transfer through the circumstellar dust by calculating the dust temperature profile assuming spherical symmetry. Results: The Mira pulsation period of 387 days was found and confirmed with two independent fitting methods. A long-term variation of ~7000 days, which cannot be attributed to orbital motion, was obtained from the analysis of the near-IR magnitudes. Reconstructed infrared SEDs were modelled successfully by a single dust shell with dust distribution enhanced by radiatively driven stellar winds. Mira temperature, dust sublimation temperature, grain diameter, density distribution, and optical depth have been obtained. Our model shows a maximum dust grain diameter of 4 μm, which is larger than expected

  18. A circumbinary planet in orbit around the short-period white dwarf eclipsing binary RR Cae

    NASA Astrophysics Data System (ADS)

    Qian, S.-B.; Liu, L.; Zhu, L.-Y.; Dai, Z.-B.; Fernández Lajús, E.; Baume, G. L.

    2012-05-01

    By using six newly determined mid-eclipse times together with those collected from the literature, we have found that the observed minus calculated (O-C) curve of RR Cae shows a cyclic change with a period of 11.9 yr and an amplitude of 14.3 s while it undergoes an upward parabolic variation [revealing a long-term period increase at a rate of ?]. The cyclic change was analysed for the light-travel-time effect that arises from the gravitational influence of a third companion. The mass of the third body was determined to be M3sin i'= 4.2(± 0.4) MJup, suggesting that it is a circumbinary giant planet when its orbital inclination is larger than 17?6. The orbital separation of the circumbinary planet from the central eclipsing binary is about 5.3(± 0.6) au. The period increase is opposite to the changes caused by angular momentum loss via magnetic braking or/and gravitational radiation; and it cannot be explained by the mass transfer between both components because of its detached configuration. These indicate that the observed upward parabolic change is only a part of a long-period (longer than 26.3 yr) cyclic variation, which may reveal the presence of another giant circumbinary planet in a wide orbit.

  19. A model for the X-ray spectrum of the symbiotic nova RR Telescopii

    NASA Astrophysics Data System (ADS)

    Jordan, S.; Murset, U.; Werner, K.

    1994-03-01

    Pointed ROSAT position sensitive proportional counter (PSPC) observations of the symbiotic nova RR Tel are presented. The PSPC pulse height distribution exhibits a rather soft energy distribution plus few, but significant counts at higher energies. We interprete this as superposition of photospheric flux from the hot component of the symbiotic binary system, and X-rays emitted by a hot plasma, probably shocked by the colliding winds from the two binary components. For modeling the stellar component we use black body emission, as well as line-blanketed non-local thermodynamic equilibrium (NLTE) model atmospheres. Additional constraints for the parameters of the hot star are provided by UV spectra obtained with IUE and VOYAGER. The parameters of the plasma are confined by published EINSTEIN count rates. A stellar atmosphere model with L = 3500 solar luminosity, Teff = 142000 K, log g = 6.5, and solar abundances, complemented with emission of several times 0.01 solar luminosity by a several 106 K hot plasma reproduces both, UV and X-ray data. For the hot star's atmosphere, any other chemical compositions can be excluded.

  20. FORBIDDEN AND INTERCOMBINATION LINES OF RR TELESCOPII: WAVELENGTH MEASUREMENTS AND ENERGY LEVELS

    SciTech Connect

    Young, P. R.; Feldman, U.; Lobel, A.

    2011-10-01

    Ultraviolet and visible spectra of the symbiotic nova RR Telescopii are used to derive reference wavelengths for many forbidden and intercombination transitions of ions +1 to +6 of elements C, N, O, Ne, Na, Mg, Al, Si, P, S, Cl, Ar, K, and Ca. The wavelengths are then used to determine new energy values for the levels within the ions' ground configurations or first excited configuration. The spectra were recorded by the Space Telescope Imaging Spectrograph of the Hubble Space Telescope and the Ultraviolet Echelle Spectrograph of the European Southern Observatory in 2000 and 1999, respectively, and cover 1140-6915 A. Particular care was taken to assess the accuracy of the wavelength scale between the two instruments. An investigation of the profiles of the emission lines reveals that the nebula consists of at least two plasma components at different velocities. The components have different densities, and a simple model of the lines' emissions demonstrates that most of the lines principally arise from the high density component. Only these lines were used for the wavelength study.

  1. RcRR1, a Rosa canina type-A response regulator gene, is involved in cytokinin-modulated rhizoid organogenesis.

    PubMed

    Gao, Bin; Fan, Lusheng; Li, Xingxing; Yang, Huifang; Liu, Fengluan; Wang, Ling; Xi, Lin; Ma, Nan; Zhao, Liangjun

    2013-01-01

    In vitro, a new protocol of plant regeneration in rose was achieved via protocorm-like bodies (PLBs) induced from the root-like organs named rhizoids that developed from leaf explants. The development of rhizoids is a critical stage for efficient regeneration, which is triggered by exogenous auxin. However, the role of cytokinin in the control of organogenesis in rose is as yet uncharacterized. The aim of this study was to elucidate the molecular mechanism of cytokinin-modulated rhizoid formation in Rosa canina. Here, we found that cytokinin is a key regulator in the formation of rhizoids. Treatment with cytokinin reduced callus activity and significantly inhibited rhizoid formation in Rosa canina. We further isolated the full-length cDNA of a type-A response regulator gene of cytokinin signaling, RcRR1, from which the deduced amino acid sequence contained the conserved DDK motif. Gene expression analysis revealed that RcRR1 was differentially expressed during rhizoid formation and its expression level was rapidly up-regulated by cytokinin. In addition, the functionality of RcRR1 was tested in Arabidopsis. RcRR1 was found to be localized to the nucleus in GFP-RcRR1 transgenic plants and overexpression of RcRR1 resulted in increased primary root length and lateral root density. More importantly, RcRR1 overexpression transgenic plants also showed reduced sensitivity to cytokinin during root growth; auxin distribution and the expression of auxin efflux carriers PIN genes were altered in RcRR1 overexpression plants. Taken together, these results demonstrate that RcRR1 is a functional type-A response regulator which is involved in cytokinin-regulated rhizoid formation in Rosa canina. PMID:24009713

  2. Conference summary - Personal views

    NASA Astrophysics Data System (ADS)

    Lub, J.

    2016-05-01

    This is a collection of remarks on the three and a half days of the RR Lyrae 2015 Conference, limited only by my own lack of attention and understanding. I end with some personal recollections on my complete failure, even though doing the necessary calculations, to spot the importance and the possible application of Fourier amplitudes and phases of the RR Lyrae light curves.

  3. 77 FR 1009 - Airworthiness Directives; Rolls-Royce plc (RR) RB211-524 Series Turbofan Engines

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-01-09

    ..., approved for IBR February 9, 2005 (70 FR 680, January 5, 2005). (3) Rolls-Royce plc Service Bulletin No. RB...-19-AD; Amendment 39-16803; AD 2011-18-21] RIN 2120-AA64 Airworthiness Directives; Rolls-Royce plc (RR... identified in this AD, contact Rolls-Royce plc, P.O. Box 31, Derby, DE24 8BJ, United Kingdom; phone:...

  4. 76 FR 65997 - Airworthiness Directives; Rolls-Royce plc (RR) RB211-535 Series Turbofan Engines

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-10-25

    ... (76 FR 30529, May 26, 2011), for all RR RB211-535E4-37, -535E4-B-37, -535E4-B- 75, and -535E4-C-37... AD Was Issued Since we issued AD 2011-11-08, Amendment 39-16707 (76 FR 30529, May 26, 2011), we found... This AD requires accomplishing the same requirements as AD 2011-11- 08 (76 FR 30529, May 26,...

  5. Recombinant baculovirus mediates dsRNA specific to rr2 delivery and its protective efficacy against WSSV infection.

    PubMed

    Rattanarojpong, Triwit; Khankaew, Suthiwat; Khunrae, Pongsak; Vanichviriyakit, Rapeepun; Poomputsa, Kanokwan

    2016-07-10

    White spot syndrome virus (WSSV) is a major causative agent in shrimp farming. Consequently, RNAi technology is an effective strategy to prevent WSSV infection in shrimp especially dsRNA targeting to rr2 of WSSV. In an effort to develop dsRNA expression in shrimp for control of WSSV infection, we developed a recombinant baculovirus expressing recombinant VP28 as the gene delivery system to carry a gene encoding dsRNA specific to rr2 for triggering the RNAi process in shrimp. The results showed that the recombinant baculovirus harboring VP28 was able to express VP28 indicated by Western blot with polyclonal antibody specific to VP28. VP28 transcript was detected in shrimp hemocytes after co-culture hemocytes with the recombinant baculovirus displaying VP28. In addition, we found that shrimp injected with the recombinant baculovirus displaying VP28 and encoding dsRNA synthetic gene specific to rr2 (Bac-VP28-dsrr2) showed the lowest cumulative mortality (33%) at 14days post infection (dpi) when compared to shrimp injected with baculovirus displaying VP28 (Bac-VP28) (64% cumulative mortality) (p<0.05). According to the results, shrimp injected with Bac-VP28-dsrr2 also showed significantly lower WSSV copies than shrimp injected with Bac-VP28 (p<0.05) along with the down-regulation of rr2 expression at 1, 3 and 7dpi. In conclusion, the Bac-VP28-dsrr2 was effective in prevention of WSSV infection. Therefore, the results obtained here can be applied to the prevention of WSSV infection by mixing the recombinant baculovirus with shrimp feed in the future. PMID:27164257

  6. Species- and congener-differences in microcystin-LR and -RR GSH conjugation in human, rat, and mouse hepatic cytosol.

    PubMed

    Buratti, Franca M; Testai, Emanuela

    2015-01-01

    The accepted pathway for MC biotransformation is GSH conjugation, occurring either spontaneously or catalyzed by GST. In the present work, the already available information on human MC metabolism have been expanded and the capacity of human GST to conjugate MC-LR has been confirmed in human liver cytosol. At physiological GSH content the spontaneous reaction predominated on the enzymatic one; the prevalence of the enzymatic reaction occurred following GSH depletion, and the shift was detectable at higher GSH levels, the lower was MC concentration. However, at low MC-LR concentrations (≤10μM), representative of repeated oral exposure, the relevance of the enzymatic reaction became predominant at GSH concentration between 1 and 2mM. MC-LR conjugate was detectable at ≥0.5mM GSH, whereas, with 10μM MC-RR detectable levels of conjugate were observed at 0.05mM GSH, a 10-fold lower concentration. Overall, our data indicate that MC-RR is more efficiently conjugated than MC-LR, especially at low concentrations. Cytosol samples from rat and mouse were used to characterize GSH conjugation of MC-LR and MC-RR, and to check for possible species differences. At physiological GSH content, in both rodent species the enzymatic reaction accounted for half of the total conjugate formation, reducing the impact of spontaneous reaction with respect to human. Rat and mouse GST showed similar MC-LR and-RR GSH conjugation, but a two-fold higher catalytic efficiency than human sample. This is mainly due to higher affinity for the substrate, with Kmapp values being an order of magnitude lower in the animal models than in human liver cytosol. More pronounced differences in the metabolism of the two variants were evidenced in rodents than in humans. PMID:25455451

  7. An easy-to-use technique to characterize cardiodynamics from first-return maps on ΔRR-intervals

    NASA Astrophysics Data System (ADS)

    Fresnel, Emeline; Yacoub, Emad; Freitas, Ubiratan; Kerfourn, Adrien; Messager, Valérie; Mallet, Eric; Muir, Jean-François; Letellier, Christophe

    2015-08-01

    Heart rate variability analysis using 24-h Holter monitoring is frequently performed to assess the cardiovascular status of a patient. The present retrospective study is based on the beat-to-beat interval variations or ΔRR, which offer a better view of the underlying structures governing the cardiodynamics than the common RR-intervals. By investigating data for three groups of adults (with normal sinus rhythm, congestive heart failure, and atrial fibrillation, respectively), we showed that the first-return maps built on ΔRR can be classified according to three structures: (i) a moderate central disk, (ii) a reduced central disk with well-defined segments, and (iii) a large triangular shape. These three very different structures can be distinguished by computing a Shannon entropy based on a symbolic dynamics and an asymmetry coefficient, here introduced to quantify the balance between accelerations and decelerations in the cardiac rhythm. The probability P111111 of successive heart beats without large beat-to-beat fluctuations allows to assess the regularity of the cardiodynamics. A characteristic time scale, corresponding to the partition inducing the largest Shannon entropy, was also introduced to quantify the ability of the heart to modulate its rhythm: it was significantly different for the three structures of first-return maps. A blind validation was performed to validate the technique.

  8. An easy-to-use technique to characterize cardiodynamics from first-return maps on ΔRR-intervals.

    PubMed

    Fresnel, Emeline; Yacoub, Emad; Freitas, Ubiratan; Kerfourn, Adrien; Messager, Valérie; Mallet, Eric; Muir, Jean-François; Letellier, Christophe

    2015-08-01

    Heart rate variability analysis using 24-h Holter monitoring is frequently performed to assess the cardiovascular status of a patient. The present retrospective study is based on the beat-to-beat interval variations or ΔRR, which offer a better view of the underlying structures governing the cardiodynamics than the common RR-intervals. By investigating data for three groups of adults (with normal sinus rhythm, congestive heart failure, and atrial fibrillation, respectively), we showed that the first-return maps built on ΔRR can be classified according to three structures: (i) a moderate central disk, (ii) a reduced central disk with well-defined segments, and (iii) a large triangular shape. These three very different structures can be distinguished by computing a Shannon entropy based on a symbolic dynamics and an asymmetry coefficient, here introduced to quantify the balance between accelerations and decelerations in the cardiac rhythm. The probability P111111 of successive heart beats without large beat-to-beat fluctuations allows to assess the regularity of the cardiodynamics. A characteristic time scale, corresponding to the partition inducing the largest Shannon entropy, was also introduced to quantify the ability of the heart to modulate its rhythm: it was significantly different for the three structures of first-return maps. A blind validation was performed to validate the technique. PMID:26328562

  9. MONITORING H{alpha} EMISSION AND CONTINUUM OF UXORs: RR Tauri

    SciTech Connect

    Bedell, Megan; Villaume, Alexa; Weiss, Lauren; Sliski, David; Strelnitski, Vladimir; Walker, Gary; Williams, Jedediyah; Henden, Arne; Krajci, Tom

    2011-11-15

    The Maria Mitchell Observatory, in collaboration with the Astrokolkhoz Observatory, started a program of photometric monitoring of UX Ori-type stars (UXORs) with narrowband interference filters (IFs; augmented with the traditional broadband filters) aimed at separating the H{alpha} emission variations from those of the continuum. We present the method of separation and the first results for RR Tau obtained in two seasons, each roughly 100 days long (2010 Winter-Spring and 2010 Fall-2011 Spring). We confirm the conclusion from previous studies that the H{alpha} emission in this star is less variable than the continuum. Although some correlation between the two is not excluded, the amplitude of H{alpha} variations is much smaller (factors of 3-5) than that of the continuum. These results are compatible with Grinin's model of UXORs, which postulates the presence of small obscuring circumstellar clouds as the cause of the continuum fading, as well as the presence of a circumstellar reflection/emission nebula, larger than the star and the obscuring clouds, which is responsible for H{alpha} emission and the effect of the 'color reversal' in deep minima. However, the results of both our broadband and narrowband photometry indicate that the obscuration model may be insufficient to explain all of the observations. Disk accretion, the presence of stellar or (proto) planetary companion(s), as well as the intrinsic variations of the star, may contribute to the observed light variations. We argue, in particular, that the H{alpha} emission may be more closely correlated with the intrinsic variations of the star than with the much stronger observed variations caused by the cloud obscuration. If this hypothesis is correct, the close monitoring of H{alpha} emission with IFs, accessible to small-size telescopes, may become an important tool in studying the physical nature of the UXORs' central stars.

  10. A new hierarchical method for inter-patient heartbeat classification using random projections and RR intervals

    PubMed Central

    2014-01-01

    Background The inter-patient classification schema and the Association for the Advancement of Medical Instrumentation (AAMI) standards are important to the construction and evaluation of automated heartbeat classification systems. The majority of previously proposed methods that take the above two aspects into consideration use the same features and classification method to classify different classes of heartbeats. The performance of the classification system is often unsatisfactory with respect to the ventricular ectopic beat (VEB) and supraventricular ectopic beat (SVEB). Methods Based on the different characteristics of VEB and SVEB, a novel hierarchical heartbeat classification system was constructed. This was done in order to improve the classification performance of these two classes of heartbeats by using different features and classification methods. First, random projection and support vector machine (SVM) ensemble were used to detect VEB. Then, the ratio of the RR interval was compared to a predetermined threshold to detect SVEB. The optimal parameters for the classification models were selected on the training set and used in the independent testing set to assess the final performance of the classification system. Meanwhile, the effect of different lead configurations on the classification results was evaluated. Results Results showed that the performance of this classification system was notably superior to that of other methods. The VEB detection sensitivity was 93.9% with a positive predictive value of 90.9%, and the SVEB detection sensitivity was 91.1% with a positive predictive value of 42.2%. In addition, this classification process was relatively fast. Conclusions A hierarchical heartbeat classification system was proposed based on the inter-patient data division to detect VEB and SVEB. It demonstrated better classification performance than existing methods. It can be regarded as a promising system for detecting VEB and SVEB of unknown patients in

  11. Homofermentative Production of d- or l-Lactate in Metabolically Engineered Escherichia coli RR1

    PubMed Central

    Chang, Dong-Eun; Jung, Heung-Chae; Rhee, Joon-Shick; Pan, Jae-Gu

    1999-01-01

    We investigated metabolic engineering of fermentation pathways in Escherichia coli for production of optically pure d- or l-lactate. Several pta mutant strains were examined, and a pta mutant of E. coli RR1 which was deficient in the phosphotransacetylase of the Pta-AckA pathway was found to metabolize glucose to d-lactate and to produce a small amount of succinate by-product under anaerobic conditions. An additional mutation in ppc made the mutant produce d-lactate like a homofermentative lactic acid bacterium. When the pta ppc double mutant was grown to higher biomass concentrations under aerobic conditions before it shifted to the anaerobic phase of d-lactate production, more than 62.2 g of d-lactate per liter was produced in 60 h, and the volumetric productivity was 1.04 g/liter/h. To examine whether the blocked acetate flux could be reoriented to a nonindigenous l-lactate pathway, an l-lactate dehydrogenase gene from Lactobacillus casei was introduced into a pta ldhA strain which lacked phosphotransacetylase and d-lactate dehydrogenase. This recombinant strain was able to metabolize glucose to l-lactate as the major fermentation product, and up to 45 g of l-lactate per liter was produced in 67 h. These results demonstrate that the central fermentation metabolism of E. coli can be reoriented to the production of d-lactate, an indigenous fermentation product, or to the production of l-lactate, a nonindigenous fermentation product. PMID:10103226

  12. Ectoparasite Raymondia lobulata infestation in relation to the reproductive cycle of its host--the greater false vampire bat Megaderma lyra.

    PubMed

    Sundari, Arasamuthu Arul; Bogdanowicz, Wieslaw; Varman, Durairaj Ragu; Marimuthu, Ganapathy; Rajan, Koilmani Emmanuvel

    2012-02-01

    To study variation of infestations by the bat fly Raymondia lobulata (Diptera: Streblidae) on the greater false vampire bat Megaderma lyra (Chiroptera: Megadermatidae), we captured individual bats at their day roost in the south of India and recorded their rate of infestation continuously for a year. All examined bats (n = 72 individuals, 202 captures) were infested with parasites (n = 3,008). However, the recorded intensity of infestation (range 1-33) was gender-related and statistically higher in females than in males (F(1, 200) = 304.45, P < 0.001). Furthermore, pregnant and lactating females had greater parasite loads than non-reproductive females and males (F(1, 63) = 23.34, P < 0.001 and F(1, 37) = 78.07, P < 0.001, respectively). No significant differences were observed between males either during mating and non-mating periods or breeding and non-breeding seasons. Analysis of the relationship between parasite infestation and the reproductive status of bats revealed that pregnant and lactating females with pups were more vulnerable hosts for parasites. Our results also suggest a well-developed coevolutionary strategy for synchronized reproduction within the host-parasite relationship and add to our understanding of how host sex and reproductive status shape the dynamics of parasitism. PMID:21923461

  13. Carbonic anhydrase-related protein XI: structure of the gene in the greater false vampire bat (Megaderma lyra) compared with human and domestic pig.

    PubMed

    Porter, Calvin A; Hewett-Emmett, David; Tashian, Richard E

    2013-06-01

    Carbonic anhydrase-related protein XI (CA-RP XI) is a member of the α-carbonic anhydrase family (encoded by the gene CA-11), which has lost features of the active site required for enzymatic activity. Using PCR, we amplified CA-11 from genomic DNA of the bat Megaderma lyra. To elucidate the gene structure, we sequenced PCR products and compared their sequences with genomic and mRNA sequences known from human and domestic pig. We identified and sequenced eight introns in the bat CA-11. Five introns (introns 3-7) are located in identical or similar positions in other members of the vertebrate α-carbonic anhydrase gene family. Two 5' introns and one 3' intron are located in the regions of little or no sequence similarity with other members of the gene family. The low sequence similarity and additional introns suggest a separate evolutionary origin for the 5' and 3' portions of the CA-RP XI gene. PMID:23417223

  14. Mid-infrared interferometry of the Mira variable RR Sco with the VLTI MIDI instrument

    NASA Astrophysics Data System (ADS)

    Ohnaka, K.; Bergeat, J.; Driebe, T.; Graser, U.; Hofmann, K.-H.; Köhler, R.; Leinert, Ch.; Lopez, B.; Malbet, F.; Morel, S.; Paresce, F.; Perrin, G.; Preibisch, Th.; Richichi, A.; Schertl, D.; Schöller, M.; Sol, H.; Weigelt, G.; Wittkowski, M.

    2005-01-01

    We present the results of the first mid-infrared interferometric observations of the Mira variable RR Sco with the MID-infrared Interferometer (MIDI) coupled to the European Southern Observatory's (ESO) Very Large Telescope Interferometer (VLTI), together with K-band observations using VLTI VINCI. The observations were carried out in June 2003, when the variability phase of the object was 0.6, using two unit telescopes (UT1 and UT3), as part of the Science Demonstration Time (SDT) program of the instrument. Projected baseline lengths ranged from 73 to 102 m, and a spectral resolution of 30 was employed in the observations, which enabled us to obtain the wavelength dependence of the visibility in the region between 8 and 13 μm. The uniform-disk diameter was found to be 18 mas between 8 and 10 μm, while it gradually increases at wavelengths longer than 10 μm to reach 24 mas at 13 μm. The uniform-disk diameter between 8 and 13 μm is significantly larger than the K-band uniform-disk diameter of 10.2 ± 0.5 mas measured using VLTI VINCI with projected baseline lengths of 15-16 m, three weeks after the MIDI observations. Our model calculations show that optically thick emission from a warm molecular envelope consisting of H2O and SiO can cause the apparent mid -infrared diameter to be much larger than the continuum diameter. We find that the warm molecular envelope model extending to ˜2.3 R\\star with a temperature of ˜1400 K and column densities of H2O and SiO of 3 × 1021 cm-2 and 1 × 1020 cm-2, respectively, can reproduce the observed uniform-disk diameters between 8 and 10 μm. The observed increase of the uniform-disk diameter longward of 10 μm can be explained by an optically thin dust shell consisting of silicate and corundum grains. The inner radius of the optically thin dust shell is derived to be 7-8 R\\star with a temperature of ˜700 K, and the optical depth at 10 μm is found to be ˜0.025. Based on observations made with the Very Large Telescope

  15. Auditory pre-experience modulates classification of affect intensity: evidence for the evaluation of call salience by a non-human mammal, the bat Megaderma lyra

    PubMed Central

    2013-01-01

    Introduction Immediate responses towards emotional utterances in humans are determined by the acoustic structure and perceived relevance, i.e. salience, of the stimuli, and are controlled via a central feedback taking into account acoustic pre-experience. The present study explores whether the evaluation of stimulus salience in the acoustic communication of emotions is specifically human or has precursors in mammals. We created different pre-experiences by habituating bats (Megaderma lyra) to stimuli based on aggression, and response, calls from high or low intensity level agonistic interactions, respectively. Then we presented a test stimulus of opposite affect intensity of the same call type. We compared the modulation of response behaviour by affect intensity between the reciprocal experiments. Results For aggression call stimuli, the bats responded to the dishabituation stimuli independent of affect intensity, emphasising the attention-grabbing function of this call type. For response call stimuli, the bats responded to a high affect intensity test stimulus after experiencing stimuli of low affect intensity, but transferred habituation to a low affect intensity test stimulus after experiencing stimuli of high affect intensity. This transfer of habituation was not due to over-habituation as the bats responded to a frequency-shifted control stimulus. A direct comparison confirmed the asymmetric response behaviour in the reciprocal experiments. Conclusions Thus, the present study provides not only evidence for a discrimination of affect intensity, but also for an evaluation of stimulus salience, suggesting that basic assessment mechanisms involved in the perception of emotion are an ancestral trait in mammals. PMID:24341839

  16. Interval ridge regression (iRR) as a fast and robust method for quantitative prediction and variable selection applied to edible oil adulteration.

    PubMed

    Jović, Ozren; Smrečki, Neven; Popović, Zora

    2016-04-01

    A novel quantitative prediction and variable selection method called interval ridge regression (iRR) is studied in this work. The method is performed on six data sets of FTIR, two data sets of UV-vis and one data set of DSC. The obtained results show that models built with ridge regression on optimal variables selected with iRR significantly outperfom models built with ridge regression on all variables in both calibration (6 out of 9 cases) and validation (2 out of 9 cases). In this study, iRR is also compared with interval partial least squares regression (iPLS). iRR outperfomed iPLS in validation (insignificantly in 6 out of 9 cases and significantly in one out of 9 cases for p<0.05). Also, iRR can be a fast alternative to iPLS, especially in case of unknown degree of complexity of analyzed system, i.e. if upper limit of number of latent variables is not easily estimated for iPLS. Adulteration of hempseed (H) oil, a well known health beneficial nutrient, is studied in this work by mixing it with cheap and widely used oils such as soybean (So) oil, rapeseed (R) oil and sunflower (Su) oil. Binary mixture sets of hempseed oil with these three oils (HSo, HR and HSu) and a ternary mixture set of H oil, R oil and Su oil (HRSu) were considered. The obtained accuracy indicates that using iRR on FTIR and UV-vis data, each particular oil can be very successfully quantified (in all 8 cases RMSEP<1.2%). This means that FTIR-ATR coupled with iRR can very rapidly and effectively determine the level of adulteration in the adulterated hempseed oil (R(2)>0.99). PMID:26838379

  17. Evaluation of techniques for estimating the power spectral density of RR-intervals under paced respiration conditions.

    PubMed

    Schaffer, Thorsten; Hensel, Bernhard; Weigand, Christian; Schüttler, Jürgen; Jeleazcov, Christian

    2014-10-01

    Heart rate variability (HRV) analysis is increasingly used in anaesthesia and intensive care monitoring of spontaneous breathing and mechanical ventilated patients. In the frequency domain, different estimation methods of the power spectral density (PSD) of RR-intervals lead to different results. Therefore, we investigated the PSD estimates of fast Fourier transform (FFT), autoregressive modeling (AR) and Lomb-Scargle periodogram (LSP) for 25 young healthy subjects subjected to metronomic breathing. The optimum method for determination of HRV spectral parameters under paced respiration was identified by evaluating the relative error (RE) and the root mean square relative error (RMSRE) for each breathing frequency (BF) and spectral estimation method. Additionally, the sympathovagal balance was investigated by calculating the low frequency/high frequency (LF/HF) ratio. Above 7 breaths per minute, all methods showed a significant increase in LF/HF ratio with increasing BF. On average, the RMSRE of FFT was lower than for LSP and AR. Therefore, under paced respiration conditions, estimating RR-interval PSD using FFT is recommend. PMID:23508826

  18. Poincaré plot analysis of autocorrelation function of RR intervals in patients with acute myocardial infarction.

    PubMed

    Chuang, Shin-Shin; Wu, Kung-Tai; Lin, Chen-Yang; Lee, Steven; Chen, Gau-Yang; Kuo, Cheng-Deng

    2014-08-01

    The Poincaré plot of RR intervals (RRI) is obtained by plotting RRIn+1 against RRIn. The Pearson correlation coefficient (ρRRI), slope (SRRI), Y-intercept (YRRI), standard deviation of instantaneous beat-to-beat RRI variability (SD1RR), and standard deviation of continuous long-term RRI variability (SD2RR) can be defined to characterize the plot. Similarly, the Poincaré plot of autocorrelation function (ACF) of RRI can be obtained by plotting ACFk+1 against ACFk. The corresponding Pearson correlation coefficient (ρACF), slope (SACF), Y-intercept (YACF), SD1ACF, and SD2ACF can be defined similarly to characterize the plot. By comparing the indices of Poincaré plots of RRI and ACF between patients with acute myocardial infarction (AMI) and patients with patent coronary artery (PCA), we found that the ρACF and SACF were significantly larger, whereas the RMSSDACF/SDACF and SD1ACF/SD2ACF were significantly smaller in AMI patients. The ρACF and SACF correlated significantly and negatively with normalized high-frequency power (nHFP), and significantly and positively with normalized very low-frequency power (nVLFP) of heart rate variability in both groups of patients. On the contrary, the RMSSDACF/SDACF and SD1ACF/SD2ACF correlated significantly and positively with nHFP, and significantly and negatively with nVLFP and low-/high-frequency power ratio (LHR) in both groups of patients. We concluded that the ρACF, SACF, RMSSDACF/SDACF, and SD1ACF/SD2ACF, among many other indices of ACF Poincaré plot, can be used to differentiate between patients with AMI and patients with PCA, and that the increase in ρACF and SACF and the decrease in RMSSDACF/SDACF and SD1ACF/SD2ACF suggest an increased sympathetic and decreased vagal modulations in both groups of patients. PMID:24356909

  19. Fractal correlation properties of R-R interval dynamics and mortality in patients with depressed left ventricular function after an acute myocardial infarction

    NASA Technical Reports Server (NTRS)

    Huikuri, H. V.; Makikallio, T. H.; Peng, C. K.; Goldberger, A. L.; Hintze, U.; Moller, M.

    2000-01-01

    BACKGROUND: Preliminary data suggest that the analysis of R-R interval variability by fractal analysis methods may provide clinically useful information on patients with heart failure. The purpose of this study was to compare the prognostic power of new fractal and traditional measures of R-R interval variability as predictors of death after acute myocardial infarction. METHODS AND RESULTS: Time and frequency domain heart rate (HR) variability measures, along with short- and long-term correlation (fractal) properties of R-R intervals (exponents alpha(1) and alpha(2)) and power-law scaling of the power spectra (exponent beta), were assessed from 24-hour Holter recordings in 446 survivors of acute myocardial infarction with a depressed left ventricular function (ejection fraction R-R interval variability were significant univariate predictors of all-cause mortality. Reduced short-term scaling exponent alpha(1) was the most powerful R-R interval variability measure as a predictor of all-cause mortality (alpha(1) <0.75, relative risk 3.0, 95% confidence interval 2.5 to 4.2, P<0.001). It remained an independent predictor of death (P<0.001) after adjustment for other postinfarction risk markers, such as age, ejection fraction, NYHA class, and medication. Reduced alpha(1) predicted both arrhythmic death (P<0.001) and nonarrhythmic cardiac death (P<0.001). CONCLUSIONS: Analysis of the fractal characteristics of short-term R-R interval dynamics yields more powerful prognostic information than the traditional measures of HR variability among patients with depressed left ventricular function after an acute myocardial infarction.

  20. THE ATRIAL NATRIURETIC PEPTIDE GENETIC VARIANT RS5065 AND RISK FOR CARDIOVASCULAR DISEASE IN THE GENERAL COMMUNITY: A NINE-YEAR FOLLOW-UP STUDY RR

    PubMed Central

    Cannone, Valentina; Huntley, Brenda; Olson, Timothy M.; Heublein, Denise M.; Scott, Christopher; Bailey, Kent R.; Redfield, Margaret M.; Rodeheffer, Richard J.; Burnett, John C.

    2014-01-01

    We analyzed the phenotype associated with the atrial natriuretic peptide (ANP) genetic variant rs5065 in a random community-based sample. We also assessed and compared the biological action of two concentrations (10−10 mol/L, 10−8 mol/L) of ANP and ANP-RR, the protein variant encoded by the minor allele of rs5065, on activation of the guanylyl cyclase-A (GC-A) and B (GC-B) receptors, production of the second messenger 3’,5’cyclic guanosine monophosphate (cGMP) in endothelial cells and endothelial permeability. Rs5065 genotypes were determined in a cross-sectional adult cohort from Olmsted County, MN (n=1623). Genotype frequencies for rs5065 were 75%, 24%, and 1% for TT, TC and CC, respectively. Multivariate analysis showed that the C allele was associated with increased risk of cerebrovascular accident (hazard ratio 1.43; 95% CI, 1.09 to 1.86; p= 0.009) and higher prevalence of myocardial infarction (odd ratio = 1.82; 95% CI, 1.07 to 3.09; p= 0.026). ANP-RR 10−8mol/L activated the GC-A receptor (83.07 ±8.31 vs no treatment 0.18±0.04 6-per well, p=0.006), ANP-RR 10−10mol/L did not. Neither 10−8mol/L nor 10−10mol/L ANP-RR activated GC-B receptor (p=0.10, p= 0.35). ANP 10−8mol/L and ANP-RR 10−8mol/L stimulated cGMP production in endothelial cells similarly (p=0.58). Both concentrations of ANP-RR significantly enhanced human aortic endothelial cell permeability (69 vs 29 RFUs, p=0.012; 58 vs 39 RFUs, p= 0.015) compared to ANP. The minor allele of rs5065 was associated with increased cardiovascular risk. ANP-RR activated the GC-A receptor, increased cGMP in endothelial cells and when compared to ANP, ANP-RR augmented endothelial cell permeability. PMID:24041948

  1. Probing the mass and structure of the Ring Nebula in Lyra with SOFIA/GREAT observations of the [CII] 158 micron line

    NASA Astrophysics Data System (ADS)

    Sahai, R.; Morris, M. R.; Werner, M. W.; Güsten, R.; Wiesemeyer, H.; Sandell, G.

    2012-06-01

    We have obtained new velocity-resolved spectra of the [CII] 158 μm line towards the Ring Nebula in Lyra (NGC 6720), one of the best-studied planetary nebulae, in order to probe its controversial 3-dimensional structure and to estimate the mass of circumstellar material in this object. We used the terahertz receiver GREAT aboard the SOFIA airborne telescope to obtain the [CII] spectra at eight locations within and outside the bright optical ring of NGC 6720. Emission was detected at all positions except for the most distant position along the nebula's minor axis, and generally covers a broad velocity range, ΔV ~ 50 km s-1 (FWZI), except at a position along the major axis located just outside the optical ring, where it is significantly narrower (ΔV ~ 25 km s-1). The one narrow spectrum appears to be probing circumstellar material lying outside the main nebular shell that has not been accelerated by past fast wind episodes from the central star, and therefore most likely comes from equatorial and/or low-latitude regions of this multipolar nebula. Along lines-of-sight passing within about 10'' of the nebular center, the CII column density is a factor 46 higher than the CO column density. The total mass of gas associated with the [CII] emission inside a circular region of diameter 87.″5 is at least 0.11 M⊙. A significant amount of [CII] flux arises from a photodissociation region immediately outside the bright optical ring, where we find a CII to CO ratio of >6.5, lower than that seen towards the central region. Comparing our data with lower-quality CI spectra, which indicate similarly large CI/CO ratios in NGC 6720, we conclude that the bulk of elemental carbon in NGC 6720 is divided roughly equally between CII and CI, and that the emissions from these species are far more robust tracers of circumstellar material than CO in this object and other evolved planetary nebulae.

  2. Robust algorithmic detection of the developed cardiac pathologies and emerging or transient abnormalities from short periods of RR data

    NASA Astrophysics Data System (ADS)

    Gavrishchaka, Valeriy V.; Senyukova, Olga

    2011-06-01

    Numerous research efforts and clinical testing have confirmed validity of heart rate variability (HRV) analysis as one of the cardiac diagnostics modalities. The majority of HRV analysis tools currently used in practice are based on linear indicators. Methods from nonlinear dynamics (NLD) provide more natural modeling framework for adaptive biological systems with multiple feedback loops. Compared to linear indicators, many NLD-based measures are much less sensitive to data artifacts and non-stationarity. However, majority of NLD measures require long time series for stable calculation. Similar restrictions also apply for linear indicators. Such requirements could drastically limit practical usability of HRV analysis in many applications, including express diagnostics, early indication of subtle directional changes during personalization of medical treatment, and robust detection of emerging or transient abnormalities. Recently we have illustrated that these challenges could be overcome by using classification framework based on boosting-like ensemble learning techniques that are capable of discovering robust meta-indicators from existing HRV measures and other incomplete empirical knowledge. In this paper we demonstrate universality of such meta-indicators and discuss operational details of their practical usage. Using such pathology examples as congestive heart failure (CHF) and arrhythmias, we show that classifiers trained on short RR segments (down to several minutes) could achieve reasonable classification accuracy (˜80-85% and higher). These indicators calculated from longer RR segments could be applicable for accurate diagnostics with classification accuracy approaching 100%. In addition, it is feasible to discover single "normal-abnormal" meta-classifier capable of detecting multiple abnormalities.

  3. 76 FR 20229 - Airworthiness Directives; Rolls-Royce plc (RR) RB211-Trent 768-60 and Trent 772-60 Turbofan Engines

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-04-12

    ... (63 FR 49416, September 16, 1998). We must receive any comments on this AD by May 27, 2011. ADDRESSES... 39-10754 (63 FR 49416, September 16, 1998), for RR RB211-Trent 700 series turbofan engines. That AD... Policies and Procedures (44 FR 11034, February 26, 1979), (3) Will not affect intrastate aviation in...

  4. AVHotRR version 2.0. Enhanced routine for near-real time monitoring of active volcanoes using IR satellite data.

    NASA Astrophysics Data System (ADS)

    Lombardo, Valerio

    2016-04-01

    The AVHotRR routine operates since 2006 to process satellite data for monitoring active volcanoes in the Mediterranean area. AVHotRR is a continually evolving program. It needs to adapt both to the availability of new incoming data and to the variability of volcanic phenomena. Though originally developed to work with Advanced Very High Resolution Radiometer (AVHRR) data, AVHotRR has been improved over the years to adapt to other sensors. Currently implemented version allows to integrate results from different dataset in order to better constrain the detection of volcanic hot-spots. In particular, the high temporal resolution of the SEVIRI instrument aboard MSG provides a key to reduce false positives in AVHRR and Moderate Resolution Imaging Spectroradiometer MODIS images. A new detection method based on the wavelet transform of SEVIRI data is proposed. Results from the application of AVHotRR to a dataset of AVHRR and SEVIRI images from Mt Etna, Italy, are presented and discussed to advantages and limitations of the algorithm.

  5. 75 FR 33738 - Airworthiness Directives; Rolls-Royce plc (RR) RB211-524 Series and RB211 Trent 500, 700, and 800...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-06-15

    ... complete Privacy Act Statement in the Federal Register published on April 11, 2000 (65 FR 19477-78... 12866; 2. Is not a ``significant rule'' under the DOT Regulatory Policies and Procedures (44 FR 11034... plc (RR) RB211-524 Series and RB211 Trent 500, 700, and 800 Series Turbofan Engines AGENCY:...

  6. Effect of Dual Cathode Buffer Layer on the Charge Carrier Dynamics of rrP3HT:PCBM Based Bulk Heterojunction Solar Cell.

    PubMed

    Singh, Ashish; Dey, Anamika; Das, Dipjyoti; Iyer, Parameswar Krishnan

    2016-05-01

    In bulk heterojunction (BHJ) solar cells, the buffer layer plays a vital role in enhancing the power conversion efficiency (PCE) by improving the charge carrier dynamics. A comprehensive understanding of the contacts is especially essential in order to optimize the performance of organic solar cells (OSCs). Although there are several fundamental reports on this subject, a proper correlation of the physical processes with experimental evidence at the photoactive layer and contact materials is essential. In this work, we incorporated three different additional buffer layers, namely, tris(8-hydroxyquinolinato) aluminum (Alq3), bathophenanthroline (BPhen) or bathocuproine (BCP) with LiF/Al as conventional cathode contact in both rrP3HT:PC61BM and rrP3HT:PC71BM blend BHJ solar cells and their corresponding photovoltaic performances were systematically correlated with their energy level diagram. The device with dual cathode buffer layer having ITO/PEDOT:PSS/blend polymer/BCP/LiF/Al configuration showed the best device performance with PCE, η = 4.96%, Jsc = 13.53 mA/cm(2), Voc = 0.60 V and FF= 61% for rrP3HT:PC71BM and PCE, η = 4.5% with Jsc = 13.3 mA/cm(2), Voc = 0.59 V and FF = 59% for rrP3HT:PC61BM. This drastic improvement in PCE in both the device configurations are due to the combined effects of better hole-blocking capacity of BCP and low work function provided by LiF/Al with the blend polymer. These results successfully explain the role of dual cathode buffer layers and their contribution to the PCE improvement and overall device performance with rrP3HT:PCBM based BHJ solar cell. PMID:27075007

  7. Solid-solution stability and preferential site-occupancy in (R-R')2Fe14B compounds

    NASA Astrophysics Data System (ADS)

    Colin, C. V.; Ito, M.; Yano, M.; Dempsey, N. M.; Suard, E.; Givord, D.

    2016-06-01

    The rare-earth (R) uniaxial anisotropy of R2Fe14B compounds with magnetic R atoms (e.g., Nd or Pr) is at the origin of the exceptional hard magnetic properties achieved in magnets based on these compounds. The uniaxial anisotropy found in Ce2Fe14B is attributed mainly to the magnetism of Fe. Ce is the most abundant R element and there has been much recent effort to fabricate magnets in which Ce is partially substituted for Nd. In the present neutron study of (R1-xCex)2Fe14B (R = La or Nd), Ce is found to enter the R2Fe14B phase over the entire composition range. The crystallographic parameters decrease with increasing Ce content and the Ce atoms preferentially occupy the smaller 4f sites. It is concluded that Ce in these (RR')2Fe14B compounds essentially maintains the intermediate valence character found in Ce2Fe14B. It is proposed that, in this intermediate valence state, Ce weakly contributes to uniaxial anisotropy, thus making a link with the fact that significant coercivity is preserved in Ce-substituted NdFeB magnets.

  8. FUSE and HST FUV Spectroscopic Analysis of the Old Novae V533 Her, DI Lac and RR Pic

    NASA Astrophysics Data System (ADS)

    Sion, Edward M.; Ruby, John J.; Godon, Patrick

    2016-01-01

    The old novae V533 Her (Nova Her 1963), DI Lac (Nova Lac 1910) and RR Pic (Nova Pic 1891) are in (or near) their quiescent stage following their nova explosions and continue to accrete at a high rate in the aftermath of their explosions. All three systems appear to be accreting at high rates long after their novae. They exhibit continua that are steeply rising into the FUV as well as absorption lines and emission lines of uncertain origin. All three have FUSE spectra which offer not only higher spectral resolution but also wavelength coverage extending down to the Lyman Limit. We have matched these FUSE spectra with existing archival HST STIS and IUE spectral coverage, and adopted the newly determined interstellar reddening corrections of Selvelli and Gilmozzi (2013). The dereddened FUV spectra have been modeled with our grids of optically thick accretion disks and hot white dwarf photospheres. We present the results of our modeling analysis and discuss implications for the poorly understood quiescent states of old novae including the role of irradiation in enhancing the rate of accretion far into quiescence.This work is supported by NASA grants NNX13AF11G and NNX13AF12G to Villanova University.

  9. Biochemical response of diverse organs in adult Danio rerio (zebrafish) exposed to sub-lethal concentrations of microcystin-LR and microcystin-RR: a balneation study.

    PubMed

    Pavagadhi, Shruti; Gong, Zhiyuan; Hande, M Prakash; Dionysiou, Dionysios D; de la Cruz, Armah A; Balasubramanian, Rajasekhar

    2012-03-01

    The present study was carried out to examine the dose-response of microcystin-LR (MC-LR) and microcystin-RR (MC-RR) toxicity in adult Danio rerio (zebrafish) under balneation conditions at various time points. The differential responses of superoxide dismutase (SOD), glutathione peroxidase (GPx), glutathione reductase (GR), and glutathione-S-transferase (GST) as biomarkers were assessed for oxygen mediated toxicity in liver, gills, intestine and brain tissues of zebrafish exposed to dissolved MC-LR and MC-RR (0.1-10.0 μgl(-1)). To investigate the time related response of biomarkers, fish were sampled after 4, 7 and 15 days of exposure. Responses varied (i) between MC-LR and MC-RR (for certain groups), (ii) for different enzymes at all time points, and (iii) for different tissues. In general, most of the enzymes followed a bell shaped curve, with an abrupt increase in activity at a particular concentration. It was observed that upon exposure to MC-LR and MC-RR, some enzymes showed an adaptive response after the first time point wherein the enzyme activity increased in some tissues. The increase in enzyme activity is suggestive of their cellular and metabolic adaptations to the continued stress and toxin exposure. Enzyme activities in general increased at lower concentrations (≤ 5.0 μgl(-1)) and decreased at higher concentrations (≥ 5.0 μgl(-1)). An abrupt change in enzyme activities was observed at a particular concentration in all the tissue enzymes. For GPx and GR, there was a differential response in the case of fish exposed to MC-LR and MC-RR, which could be due to the difference in toxicity potentials of these cyanotoxins. In general, initial stress conditions were observed in most of the tissue enzymes following the exposure to microcystins (MCs). This observation suggests that MCs found in trace levels are likely to have deleterious effects on aquatic organisms and can trigger a variety of biochemical responses depending on their specific toxicity

  10. A recombinant chimera composed of repeat region RR1 of Mycoplasma hyopneumoniae adhesin with Pseudomonas exotoxin: in vivo evaluation of specific IgG response in mice and pigs.

    PubMed

    Chen, J R; Liao, C W; Mao, S J; Weng, C N

    2001-06-22

    Using the binding and translocation domain of Pseudomonas exotoxin A [domain III deleted PE termed PE(DeltaIII)] as a vehicle, this study characterized and evaluated a novel application of PE toxin in Mycoplasma hyopneumoniae adhesin used as an immunogen. PCR and sequence analysis revealed that 16 copies of AAKPV(E) in tandem repeat region 1 (RR1) of M. hyopneumoniae 97kDa adhesion were successfully fused to the downstream of PE(DeltaIII) to create a subunit vaccine, i.e. PE(DeltaIII)-RR1. This chimeric protein, over-expressed in inclusion bodies of E. coli BL21(DE3)pLysS, was characterized by a monoclonal antibody (MAb) F2G5 prepared against RR1 of the 97kDa adhesin and was readily purified. The data indicated that the epitope recognized by MAb F2G5 was located in the structure of PE(DeltaIII)-RR1. Using ELISA and Western blot analyses, the specific IgG immune response against RR1 and whole adhesin in mice immunized with PE(DeltaIII)-RR1 was found more marked than that in mice immunized with the M. hyopneumoniae whole cells. Similarly, PE(DeltaIII)-RR1 also stimulated a remarkable IgG response against RR1 in pigs compared to that in pigs immunized with the conventional M. hyopneumoniae vaccine. The PE(DeltaIII)-RR1 would be potentially useful for the future development of a M. hyopneumoniae adhesin vaccine. PMID:11348771

  11. Characterization of the response to ecdysteroid of a novel cuticle protein R&R gene in the honey bee, Apis cerana cerana.

    PubMed

    Sun, Rujiang; Zhang, Yuanying; Xu, Baohua

    2013-09-01

    Genes encoding cuticle proteins are helpful subjects to study the molecular mechanisms of insect molting and metamorphosis. In this study, we isolated and characterized a novel cuticle protein R&R gene, referred to as AccCPR1, from Apis cerana cerana. The open reading frame of AccCPR1 has a length of 573 nt and encodes a protein of 190 amino acids that contains a chitin binding region and is a typical cuticle R&R-2 protein. Five putative E74 binding sites and four BR-C binding sites were predicted in the 5'-flanking region, which suggests a potential function in molting and metamorphosis. RT-qPCR showed that AccCPR1 transcript occurred as the ecdysteroid titer decreased after reaching a peak, which suggests AccCPR1 expression requires a "pulse" regimen of ecdysteroids. This hypothesis was tested using different experimental strategies. When larvae were reared with different concentrations of 20E in their diet, the ecdysteroid peak repressed AccCPR1 expression. Exposure of the thoracic integument of the pupae in vitro to different concentration of 20E repressed AccCPR1 expression, which recovered after the removal of 20E. These results suggest that AccCPR1 is a typical cuticle R&R-2 protein that plays an important role in development, and an ecdysteroid pulse is critical for high AccCPR1 gene expression. PMID:23856183

  12. Biology and survival of extremely halophilic archaeon Haloarcula marismortui RR12 isolated from Mumbai salterns, India in response to salinity stress

    PubMed Central

    Thombre, Rebecca S.; Shinde, Vinaya D.; Oke, Radhika S.; Dhar, Sunil Kumar; Shouche, Yogesh S.

    2016-01-01

    Haloarchaea are unique microorganism’s resistant to environmental and osmotic stresses and thrive in their habitats despite extreme fluctuating salinities. In the present study, haloarchaea were isolated from hypersaline thalossohaline salterns of Bhandup, Mumbai, India and were identified as Haloferax prahovense, Haloferax alexandrines, Haloferax lucentense, Haloarcula tradensis, Haloarcula marismortui and Haloarcula argentinensis. The mechanism of adaptation to contrasting salinities (1.5 M and 4.5 M) was investigated in the extreme haloarchaeon, Hal. marismortui RR12. Hal. marismortui RR12 increased the intracellular sequestration of K+ and Cl− ions in hypo salinity and hyper salinity respectively as detected by Energy-dispersive X-ray spectroscopy microanalysis (EDAX) and Inductively Coupled Plasma- atomic Emission Spectroscopy (ICP-AES) indicating the presence of ‘salt-in’ strategy of osmoadaptation. As a cellular response to salinity stress, it produced small heat shock like proteins (sHSP) identified using MALDI-TOF MS and increased the production of protective red carotenoid pigment. This is the first report on the study of the concomitant cellular, molecular and physiological mechanism adapted by Hal. marismortui RR12 when exposed to contrasting salinities in external environment. PMID:27231230

  13. The Optical Gravitational Lensing Experiment. The OGLE-III Catalog of Variable Stars. IX. RR Lyr Stars in the Small Magellanic Cloud

    NASA Astrophysics Data System (ADS)

    Soszyński, I.; Udalski, A.; Szymański, M. K.; Kubiak, J.; Pietrzyński, G.; Wyrzykowski, Ł.; Ulaczyk, K.; Poleski, R.

    2010-09-01

    The ninth part of the OGLE-III Catalog of Variable Stars (OIII-CVS) comprises RR Lyr stars in the Small Magellanic Cloud (SMC). Our sample consists of 2475 variable stars, of which 1933 pulsate in the fundamental mode (RRab), 175 are the first overtone pulsators (RRc), 258 oscillate simultaneously in both modes (RRd) and 109 stars are suspected second-overtone pulsators (RRe). 30 objects are Galactic RR Lyr stars seen in the foreground of the SMC. We discuss some statistical features of the sample. Period distributions show distinct differences between SMC and LMC populations of RR Lyr variable stars, with the SMC stars having on average longer periods. The mean periods for RRab, RRc and RRe stars are 0.596, 0.366 and 0.293 days, respectively. The mean apparent magnitudes of RRab stars are equal to 19.70 mag in the V-band and 19.12 mag in the I-band. Spatial distribution of RRLyr stars shows that the halo of the SMC is roughly round in the sky, however the density map reveals two maxima near the center of the SMC. For each object the multi-epoch V- and I-band photometry collected over 8 or 13 years of observations and finding charts are available to the astronomical community from the OGLE Internet archive.

  14. Biology and survival of extremely halophilic archaeon Haloarcula marismortui RR12 isolated from Mumbai salterns, India in response to salinity stress.

    PubMed

    Thombre, Rebecca S; Shinde, Vinaya D; Oke, Radhika S; Dhar, Sunil Kumar; Shouche, Yogesh S

    2016-01-01

    Haloarchaea are unique microorganism's resistant to environmental and osmotic stresses and thrive in their habitats despite extreme fluctuating salinities. In the present study, haloarchaea were isolated from hypersaline thalossohaline salterns of Bhandup, Mumbai, India and were identified as Haloferax prahovense, Haloferax alexandrines, Haloferax lucentense, Haloarcula tradensis, Haloarcula marismortui and Haloarcula argentinensis. The mechanism of adaptation to contrasting salinities (1.5 M and 4.5 M) was investigated in the extreme haloarchaeon, Hal. marismortui RR12. Hal. marismortui RR12 increased the intracellular sequestration of K(+) and Cl(-) ions in hypo salinity and hyper salinity respectively as detected by Energy-dispersive X-ray spectroscopy microanalysis (EDAX) and Inductively Coupled Plasma- atomic Emission Spectroscopy (ICP-AES) indicating the presence of 'salt-in' strategy of osmoadaptation. As a cellular response to salinity stress, it produced small heat shock like proteins (sHSP) identified using MALDI-TOF MS and increased the production of protective red carotenoid pigment. This is the first report on the study of the concomitant cellular, molecular and physiological mechanism adapted by Hal. marismortui RR12 when exposed to contrasting salinities in external environment. PMID:27231230

  15. Nonradial oscillations in classical pulsating stars. Predictions and discoveries

    NASA Astrophysics Data System (ADS)

    Dziembowski, W. A.

    2016-05-01

    After a brief historical introduction and recalling basic concepts of stellar oscillation theory, I focus my review on interpretation of secondary periodicities found in RR Lyrae stars and Cepheids as a manifestation of nonradial mode excitation.

  16. Hypercoordinate ketone adducts of electrophilic η3-H2SiRR' ligands on ruthenium as key intermediates for efficient and robust catalytic hydrosilation.

    PubMed

    Lipke, Mark C; Tilley, T Don

    2014-11-19

    The electrophilic η(3)-H2SiRR' σ-complexes [PhBP(Ph)3]RuH(η(3)-H2SiRR') (RR' = MePh, 1a; Ph2, 1b; [PhBP(Ph)3](-) = [PhB(CH2PPh2)3](-)) are efficient catalysts (0.01-2.5 mol % loading) for the hydrosilation of ketones with PhMeSiH2, Ph2SiH2, or EtMe2SiH. An alkoxy complex [PhBP(Ph)3]Ru-OCHPh2 (4b) was observed (by (31)P{(1)H} NMR spectroscopy) as the catalyst resting state during hydrosilation of benzophenone with EtMe2SiH. A different catalyst resting state was observed for reactions using PhMeSiH2 or Ph2SiH2, and was identified as a silane σ-complex [PhBP(Ph)3]RuH[η(2)-H-SiRR'(OCHPh2)] (RR' = MePh, 5a; Ph2, 5b) using variable temperature multinuclear NMR spectroscopy (-80 to 20 °C). The hydrosilation of benzophenone with PhMeSiH2 and 1a was examined by (1)H NMR spectroscopy at -18 °C (in CD2Cl2), and this revealed that either 1a, 5a, or both 1a and 5a could be observed as resting states of the catalytic cycle, depending on the initial [PhMeSiH2]:[benzophenone] ratio. Kinetic studies revealed two possible expressions for the rate of product formation, depending on which catalyst resting state was present (rate = kobs[PhMeSiH2][5a] and rate = k'obs[benzophenone][1a]). Computational methods (DFT, b3pw91, 6-31G(d,p)/LANL2DZ) were used to determine a model catalytic cycle for the hydrosilation of acetone with PhMeSiH2. A key step in this mechanism involves coordination of acetone to the silicon center of 1a-DFT, which leads to insertion of the carbonyl group into an Si-H bond (that is part of a Ru-H-Si 3c-2e bond). This generates an intermediate analogous to 5a (5a-i-DFT), and the final product is displaced from 5a-i-DFT by an associative process involving PhMeSiH2. PMID:25347044

  17. On the possible leakage of ET-RR1 liquid waste tank: hydrological and migration modes studies.

    PubMed

    Mahmoud, N S; El-Hemamy, S T

    2005-03-20

    The first Egyptian (ET-RR1) research reactor has been in operation since 1961 at the Egyptian Atomic Energy Authority (EAEA) Inshas site. Therefore, at present, it faces a serious problem due to aging equipment, especially those directly in contact with the environment such as the underground settling tanks of nuclear and radioactive waste. The possible leakage of radionuclides from these aging tanks and their migration to the aquifer was studied using instantaneous release. This study was done based on the geological and hydrological characteristics of the site, which were obtained from the hydrogeological data of 25 wells previously drilled at the site of the reactor[1]. These data were used to calculate the trend of water levels, hydraulic gradient, and formulation of water table maps from 1993-2002. This information was utilized to determine water velocity in the unsaturated zone. Radionuclides released from the settling tank to the aquifer were screened according to the radionuclides that have high migration ability and high activity. The amount of fission and activation products of the burned fuels that contaminated the water content of the reactor pool were considered as 10% of the original spent fuel. The radionuclides considered in this case were H-3, Sr-90, Zr-93, Tc-99, Cd-113, Cs-135, Cs-137, Sm-151, Pu-238, Pu-240, Pu-241, and Am-241. The instantaneous release was analyzed by theoretical calculations, taking into consideration the migration mechanism of the various radionuclides through the soil space between the tank bottom and the aquifer. The migration mechanism through the unsaturated zone was considered depending on soil type, thickness of the unsaturated zone, water velocity, and other factors that are specific for each radionuclide, namely retardation factor, which is the function of the specific distribution coefficient of each radionuclide. This was considered collectively as delay time. Meanwhile, the mechanism of radionuclide migration

  18. Predicting the effect of D,L-sotalol on ventricular tachycardia inducibility from the RR variability response

    PubMed Central

    Brembilla-Perrot, B; Houriez, P; Claudon, O; Preiss, J; Beurrier, D

    1999-01-01

    AIM—To find a rapid way of identifying non-responders to D,L-sotalol in patients with ventricular tachycardia.
METHODS—Programmed ventricular stimulation and RR variability were studied in the control state and 10 days after treatment with 160 to 320 mg of D,L-sotalol in 36 consecutive patients with ventricular tachycardia.
RESULTS—In 14 patients (group I) D,L-sotalol suppressed ventricular tachycardia inducibility. In 22 patients (group II) sustained ventricular tachycardia remained inducible during D,L-sotalol treatment. The ventricular tachycardia rate was slowed in eight patients and unchanged or accelerated in 14. At baseline, heart rate variability was similar in both groups. During treatment with D,L-sotalol, variables reflecting parasympathetic activity (pNN50, rMSSD, and high frequency amplitude (HF)) increased in both groups: HF increased from (mean (SD)) 75 (68) to 146 (134) in group I (p < 0.05) and from 60 (49) to 125 (79) in group II (p < 0.05). Other variables were unchanged in group I. In group II, the variables associated with sympathetic activity (coefficient of variance (CV), ratio of low frequency amplitude (LF) to HF) decreased significantly: CV decreased from 13 (4) to 9 (2) (p < 0.001) and LF/HF from 4.74 (3.02) to 3.00 (2.02) (p < 0.05).
CONCLUSIONS—The β blocking effect of D,L-sotalol produced a significant improvement over control values in indices of parasympathetic tone in all treated patients. However, the heart rate variability indices related to sympathetic activity were decreased only in non-responders. This effect of D,L-sotalol on heart rate variability could help detect non-responders to the drug and avoid an electrophysiological study.


Keywords: sotalol; ventricular tachycardia; heart rate variability PMID:10455080

  19. The Projects for Onboard Autonomy (PROBA2) Science Centre: Sun Watcher Using APS Detectors and Image Processing (SWAP) and Large-Yield Radiometer (LYRA) Science Operations and Data Products

    NASA Astrophysics Data System (ADS)

    Zender, J.; Berghmans, D.; Bloomfield, D. S.; Cabanas Parada, C.; Dammasch, I.; De Groof, A.; D'Huys, E.; Dominique, M.; Gallagher, P.; Giordanengo, B.; Higgins, P. A.; Hochedez, J.-F.; Yalim, M. S.; Nicula, B.; Pylyser, E.; Sanchez-Duarte, L.; Schwehm, G.; Seaton, D. B.; Stanger, A.; Stegen, K.; Willems, S.

    2013-08-01

    The PROBA2 Science Centre (P2SC) is a small-scale science operations centre supporting the Sun observation instruments onboard PROBA2: the EUV imager Sun Watcher using APS detectors and image Processing (SWAP) and Large-Yield Radiometer (LYRA). PROBA2 is one of ESA's small, low-cost Projects for Onboard Autonomy (PROBA) and part of ESA's In-Orbit Technology Demonstration Programme. The P2SC is hosted at the Royal Observatory of Belgium, co-located with both Principal Investigator teams. The P2SC tasks cover science planning, instrument commanding, instrument monitoring, data processing, support of outreach activities, and distribution of science data products. PROBA missions aim for a high degree of autonomy at mission and system level, including the science operations centre. The autonomy and flexibility of the P2SC is reached by a set of web-based interfaces allowing the operators as well as the instrument teams to monitor quasi-continuously the status of the operations, allowing a quick reaction to solar events. In addition, several new concepts are implemented at instrument, spacecraft, and ground-segment levels allowing a high degree of flexibility in the operations of the instruments. This article explains the key concepts of the P2SC, emphasising the automation and the flexibility achieved in the commanding as well as the data-processing chain.

  20. A Detailed Study of the Variable Stars in Five Galactic Globular Clusters: IC4499, NGC4833, NGC6171 (M107), NGC6402 (M14), and NGC6584

    NASA Astrophysics Data System (ADS)

    Murphy, Brian W.; Darragh, Andrew; Hettinger, Paul; Hibshman, Adam; Johnson, Elliott W.; Liu, Z. J.; Pajkos, Michael A.; Stephenson, Hunter R.; Vondersaar, John R.; Conroy, Kyle E.; McCombs, Thayne A.; Reinhardt, Erik D.; Toddy, Joseph

    2015-08-01

    We present the results of an extensive study intended to search for and properly classify the variable stars in five galactic globular clusters. Each of the five clusters was observed hundreds to thousands of times over a time span ranging from 2 to 4 years using the SARA 0.6m located at Cerro Tololo Interamerican Observatory. The images were analyzed using the image subtract method of Alard (2000) to identify and produce light curves of all variables found in each cluster. In total we identified 373 variables with 140 of these being newly discovered increasing the number of known variables stars in these clusters by 60%. Of the total we have identified 312 RR Lyrae variables (187 RR0, 18 RR01, 99 RR1, 8 RR2), 9 SX Phe stars, 6 Cepheid variables, 11 eclipsing variables, and 35 long period variables. For IC4499 we identified 64 RR0, 18 RR01, 14 RR1, 4 RR2, 1 SX Phe, 1 eclipsing binary, and 2 long period variables. For NGC4833 we identified 10 RR0, 7 RR1, 2 RR2, 6 SX Phe, 5 eclipsing binaries, and 9 long period variables. For NGC6171 (M107) we identified 13 RR0, 7 RR1, and 1 SX Phe. For NGC6402 (M14) we identified 52 RR0, 56 RR1, 1 RR2, 1 SX Phe, 6 Cepheids, 1 eclipsing binary, and 15 long period variables. For NGC6584 we identified 48 RR0, 15 RR1, 1 RR2, 5 eclipsing binaries, and 9 long period variables. Using the RR Lyrae variables we found the mean V magnitude of the horizontal branch to be VHB = ⟨V ⟩RR = 17.63, 15.51, 15.72, 17.13, and 16.37 magnitudes for IC4499, NGC4833, NGC6171 (M107), NGC6402 (M14), and NGC6584, respectively. From our extensive data set we were able to obtain sufficient temporal and complete phase coverage of the RR Lyrae variables. This has allowed us not only to properly classify each of the RR Lyrae variables but also to use Fourier decomposition of the light curves to further analyze the properties of the variable stars and hence physical properties of each clusters. In this poster we will give the temperature, radius, stellar mass

  1. A survey of HK, HPt, and RR domains and their organization in two-component systems and phosphorelay proteins of organisms with fully sequenced genomes

    PubMed Central

    Salvado, Baldiri; Vilaprinyo, Ester; Sorribas, Albert

    2015-01-01

    Two Component Systems and Phosphorelays (TCS/PR) are environmental signal transduction cascades in prokaryotes and, less frequently, in eukaryotes. The internal domain organization of proteins and the topology of TCS/PR cascades play an important role in shaping the responses of the circuits. It is thus important to maintain updated censuses of TCS/PR proteins in order to identify the various topologies used by nature and enable a systematic study of the dynamics associated with those topologies. To create such a census, we analyzed the proteomes of 7,609 organisms from all domains of life with fully sequenced and annotated genomes. To begin, we survey each proteome searching for proteins containing domains that are associated with internal signal transmission within TCS/PR: Histidine Kinase (HK), Response Regulator (RR) and Histidine Phosphotranfer (HPt) domains, and analyze how these domains are arranged in the individual proteins. Then, we find all types of operon organization and calculate how much more likely are proteins that contain TCS/PR domains to be coded by neighboring genes than one would expect from the genome background of each organism. Finally, we analyze if the fusion of domains into single TCS/PR proteins is more frequently observed than one might expect from the background of each proteome. We find 50 alternative ways in which the HK, HPt, and RR domains are observed to organize into single proteins. In prokaryotes, TCS/PR coding genes tend to be clustered in operons. 90% of all proteins identified in this study contain just one of the three domains, while 8% of the remaining proteins combine one copy of an HK, a RR, and/or an HPt domain. In eukaryotes, 25% of all TCS/PR proteins have more than one domain. These results might have implications for how signals are internally transmitted within TCS/PR cascades. These implications could explain the selection of the various designs in alternative circumstances. PMID:26339559

  2. The impact of varying autonomic states on the dynamic beat-to-beat QT–RR and QT–TQ interval relationships

    PubMed Central

    Fossa, A A

    2008-01-01

    The beat-to-beat dynamicity of the QT–RR interval relationship is difficult to assess with the use of traditional correction factors (QTc) and changes in QTc do not accurately reflect or quantify arrhythmogenic risk. Further, the interpretation of arrhythmogenic risk is influenced by autonomic state. To visualize the QT–RR interval dynamics under varying conditions of autonomic state from impaired repolarization, we have developed a system to sequentially plot the beat-to-beat confluence of ECG data or ‘clouds' obtained from conscious dogs and humans. To represent the non-uniformity of the clouds, a bootstrap sampling method that computes the mathematical centre of the uncorrected beat-to-beat QT value (QTbtb) and defines the upper and lower 95% confidence bounds is used. The same method can also be used to examine heterogeneity, hysteresis (both acceleration and deceleration) and restitution (beat-to-beat QT–TQ interval relationship). Impaired repolarization with the combination of E-4031 and L-768,673 (inhibitor of IKs current) increased heterogeneity of restitution at rest 55–91%; increased hysteresis during heart rate acceleration after isoproterenol challenge by approximately 40–60%; and dramatically diminished the minimum TQ boundary by 72% to only 28 ms. Impaired repolarization alters restitution during normal sinus rhythm and increases hysteresis/heterogeneity during heart rate acceleration following sympathetic stimulation. These findings are supported by similar clinical observations in LQT1 and LQT2 syndromes. Therefore, the assessment of the dynamic QT–RR and QT–TQ interval relationships through quantification of heterogeneity, hysteresis and restitution may allow a more accurate non-invasive evaluation of the conditions leading to cardiac arrhythmia. PMID:18663381

  3. Standard operating procedures for collection of soil and sediment samples for the Sediment-bound Contaminant Resiliency and Response (SCoRR) strategy pilot study

    USGS Publications Warehouse

    Fisher, Shawn C.; Reilly, Timothy J.; Jones, Daniel K.; Benzel, William M.; Griffin, Dale W.; Loftin, Keith A.; Iwanowicz, Luke R.; Cohl, Jonathan A.

    2015-01-01

    An understanding of the effects on human and ecological health brought by major coastal storms or flooding events is typically limited because of a lack of regionally consistent baseline and trends data in locations proximal to potential contaminant sources and mitigation activities, sensitive ecosystems, and recreational facilities where exposures are probable. In an attempt to close this gap, the U.S. Geological Survey (USGS) has implemented the Sediment-bound Contaminant Resiliency and Response (SCoRR) strategy pilot study to collect regional sediment-quality data prior to and in response to future coastal storms. The standard operating procedure (SOP) detailed in this document serves as the sample-collection protocol for the SCoRR strategy by providing step-by-step instructions for site preparation, sample collection and processing, and shipping of soil and surficial sediment (for example, bed sediment, marsh sediment, or beach material). The objectives of the SCoRR strategy pilot study are (1) to create a baseline of soil-, sand-, marsh sediment-, and bed-sediment-quality data from sites located in the coastal counties from Maine to Virginia based on their potential risk of being contaminated in the event of a major coastal storm or flooding (defined as Resiliency mode); and (2) respond to major coastal storms and flooding by reoccupying select baseline sites and sampling within days of the event (defined as Response mode). For both modes, samples are collected in a consistent manner to minimize bias and maximize quality control by ensuring that all sampling personnel across the region collect, document, and process soil and sediment samples following the procedures outlined in this SOP. Samples are analyzed using four USGS-developed screening methods—inorganic geochemistry, organic geochemistry, pathogens, and biological assays—which are also outlined in this SOP. Because the SCoRR strategy employs a multi-metric approach for sample analyses, this

  4. K2 variable catalogue - II. Machine learning classification of variable stars and eclipsing binaries in K2 fields 0-4

    NASA Astrophysics Data System (ADS)

    Armstrong, D. J.; Kirk, J.; Lam, K. W. F.; McCormac, J.; Osborn, H. P.; Spake, J.; Walker, S.; Brown, D. J. A.; Kristiansen, M. H.; Pollacco, D.; West, R.; Wheatley, P. J.

    2016-02-01

    We are entering an era of unprecedented quantities of data from current and planned survey telescopes. To maximize the potential of such surveys, automated data analysis techniques are required. Here we implement a new methodology for variable star classification, through the combination of Kohonen Self-Organizing Maps (SOMs, an unsupervised machine learning algorithm) and the more common Random Forest (RF) supervised machine learning technique. We apply this method to data from the K2 mission fields 0-4, finding 154 ab-type RR Lyraes (10 newly discovered), 377 δ Scuti pulsators, 133 γ Doradus pulsators, 183 detached eclipsing binaries, 290 semidetached or contact eclipsing binaries and 9399 other periodic (mostly spot-modulated) sources, once class significance cuts are taken into account. We present light-curve features for all K2 stellar targets, including their three strongest detected frequencies, which can be used to study stellar rotation periods where the observed variability arises from spot modulation. The resulting catalogue of variable stars, classes, and associated data features are made available online. We publish our SOM code in PYTHON as part of the open source PYMVPA package, which in combination with already available RF modules can be easily used to recreate the method.

  5. Before the Bar: Kinematic Detection of a Spheroidal Metal-poor Bulge Component

    NASA Astrophysics Data System (ADS)

    Kunder, Andrea; Rich, R. M.; Koch, A.; Storm, J.; Nataf, D. M.; De Propris, R.; Walker, A. R.; Bono, G.; Johnson, C. I.; Shen, Juntai; Li, Z.-Y.

    2016-04-01

    We present 947 radial velocities of RR Lyrae variable stars in four fields located toward the Galactic bulge, observed within the data from the ongoing Bulge RR Lyrae Radial Velocity Assay (BRAVA-RR). We show that these RR Lyrae stars (RRLs) exhibit hot kinematics and null or negligible rotation and are therefore members of a separate population from the bar/pseudobulge that currently dominates the mass and luminosity of the inner Galaxy. Our RRLs predate these structures and have metallicities, kinematics, and spatial distribution that are consistent with a “classical” bulge, although we cannot yet completely rule out the possibility that they are the metal-poor tail of a more metal-rich ([{Fe}/{{H}}]∼ -1 dex) halo–bulge population. The complete catalog of radial velocities for the BRAVA-RR stars is also published electronically.

  6. Appearance of Planktothrix rubescens Bloom with [D-Asp3, Mdha7]MC–RR in Gravel Pit Pond of a Shallow Lake-Dominated Area

    PubMed Central

    Vasas, Gábor; Farkas, Oszkár; Borics, Gábor; Felföldi, Tamás; Sramkó, Gábor; Batta, Gyula; Bácsi, István; Gonda, Sándor

    2013-01-01

    Blooms of toxic cyanobacteria are well-known phenomena in many regions of the world. Microcystin (MC), the most frequent cyanobacterial toxin, is produced by entirely different cyanobacteria, including unicellular, multicellular filamentous, heterocytic, and non-heterocytic bloom-forming species. Planktothrix is one of the most important MC-producing genera in temperate lakes. The reddish color of cyanobacterial blooms viewed in a gravel pit pond with the appearance of a dense 3 cm thick layer (biovolume: 28.4 mm3 L−1) was an unexpected observation in the shallow lake-dominated alluvial region of the Carpathian Basin. [d-Asp3, Mdha7]MC–RR was identified from the blooms sample by MALDI-TOF and NMR. Concentrations of [d-Asp3, Mdha7]MC–RR were measured by capillary electrophoresis to compare the microcystin content of the field samples and the isolated, laboratory-maintained P. rubescens strain. In analyzing the MC gene cluster of the isolated P. rubescens strain, a deletion in the spacer region between mcyE and mcyG and an insertion were located in the spacer region between mcyT and mcyD. The insertion elements were sequenced and partly identified. Although some invasive tropical cyanobacterial species have been given a great deal of attention in many recent studies, our results draw attention to the spread of the alpine organism P. rubescens as a MC-producing, bloom-forming species. PMID:24351711

  7. Autonomic nervous system dysfunction in workers exposed to lead, zinc, and copper in relation to peripheral nerve conduction: a study of R-R interval variability

    SciTech Connect

    Murata, K.; Araki, S. )

    1991-01-01

    Quantitative assessment of the autonomic neurotoxicity due to lead was undertaken by measuring variability in the electrocardiographic R-R interval (CVRR) in 16 male workers exposed to lead, zinc, copper, and tin and in 16 unexposed control subjects. Two component coefficients of variation in the R-R interval, the C-CVRSA (respiratory sinus arrhythmia) and C-CVMWSA (Mayer wave related sinus arrhythmia), were examined; these indices are considered to reflect parasympathetic and sympathetic activities, respectively. Maximal motor and sensory conduction velocities (MCV and SCV) in the median nerve were also measured. In the 16 exposed workers, blood lead concentrations ranged from 16 to 60 (mean 34) micrograms/dl. The CVRR and C-CVRSA were found to be significantly reduced in the workers with elevated lead, zinc, and copper absorption as compared to unexposed control subjects; also, the MCV and SCV were significantly slowed. The C-CVMWSA was not significantly reduced, and was positively related to plasma zinc concentrations. No significant relationships were found between indicators of lead and copper absorption and these electrophysiological measurements. These data suggest that subclinical toxicity of lead occurs in the parasympathetic component of the autonomic nervous system as well as in the peripheral nerves. Zinc may antagonize the autonomic nervous dysfunction caused by lead.

  8. A non-randomised controlled trial of the R&R2MHP cognitive skills program in high risk male offenders with severe mental illness

    PubMed Central

    2013-01-01

    Background The growing popularity of offending behavior programs has led to the interest of whether such programs are effective with mentally disordered offenders. This study aimed to evaluate the effectiveness of the Reasoning and Rehabilitation program adapted for offenders with severe mental illness (R&R2 MHP). Methods A sample of 59 adult high risk males detained in a high secure hospital completed questionnaires at baseline and post treatment to assess violent attitudes, anger, coping processes and social problem-solving. An informant measure of social and psychological functioning, including disruptive behavior, was completed by staff at the same time. The data of 30 patients who participated in the group condition were compared using intention to treat analysis with 29 controls who received treatment as usual. Results 80% of group participants completed the program. In contrast to controls, significant medium-large treatment effects were found at outcome on self-reported measures of violent attitudes, social problem-solving and coping processes. Improvements were endorsed by informant ratings of disruptive behavior, social and psychological functioning. Conclusions The R&R2MHP had a comparatively low dropout rate and was effective in a sample of high risk mentally disordered offenders requiring detention in high security. Future research should use a randomized controlled design. Trial registration Current Controlled Trials ACTRN12613000216718. PMID:24498962

  9. Convenient Relations for the Estimation of Bond Ionicity in A-B Type Compounds.

    ERIC Educational Resources Information Center

    Barbe, Jacques

    1983-01-01

    Bond character is directly conditioned by the peculiar capacity of bonded atoms to exchange electrons; such a capacity is clearly illustrated by electronegativity. The determination of bond character using the electronegativity difference between the bonded atoms is discussed and an equation focusing on relationships between bonds is provided. (JN)

  10. Expression of resistance to Friend virus-stimulated erythropoiesis in bone marrow chimeras containing Fv-2rr and Fv-2ss bone marrow

    SciTech Connect

    Silver, J.; Teich, N.

    1981-07-01

    Bone marrow chimeras were formed containing mixtures of DBA/2 (Fv-2ss, Hbbdd) and B10.D2 (Fv-2rr, Hbbss) bone marrow. When these mice were infected with the polycythemia-inducing strain of Friend virus, erythropoiesis was stimulated, but the proportion of B10.D2 hemoglobin fell rapidly and newly synthesized hemoglobin was essentially all of the DBA/2 type. The treatment of infected polycythemic chimeras with phenylhydrazine lowered the hematocrit and restored the synthesis of B10.D2 hemoglobin. These results imply that B10.D2 erythroid precursors are intrinsically resistant to Friend virus-stimulated erythropoiesis. The experiments also suggest that virus-stimulated erythropoiesis is not mediated by a factor or cell-cell interactions, unless such factors or interactions do not act across strain barriers.

  11. Association of decreased variation of R-R interval and elevated serum C-reactive protein level in a general population in Japan.

    PubMed

    Kon, Hisashi; Nagano, Masahide; Tanaka, Fumitaka; Satoh, Kenyu; Segawa, Toshie; Nakamura, Motoyuki

    2006-11-01

    Several studies have suggested that an increased high sensitivity C-reactive protein (hsCRP) level is a strong independent predictor of increased risk for atherosclerotic cardiovascular mortality and morbidity. Reduced heart rate variability (HRV) has also been reported to predict cardiovascular events such as sudden death and myocardial infarction in apparently healthy subjects. The aim of this cross-sectional study was to test the possible correlation between variation of the R-R interval as one of the markers of HRV and serum hsCRP levels in a general population in Japan. Resting, supine, 2-minute, beat-to-beat heart rate data were collected in 823 randomly selected participants enrolled in our cohort study. The coefficient of variation of the R-R interval (CVrr) was obtained as a parameter of HRV. To determine which factors predict the presence of low CVrr (below the 5 percentile) in this group, we performed a multivariate logistic regression analysis using cardiovascular risk factors and an elevated hsCRP level as independent variables. The lowest CVrr group showed significantly higher hsCRP levels compared to those of other quartiles (P < 0.01). After adjustment for confounding factors such as age, heart rate, obesity, hypercholesterolemia, and hypertension by multivariate logistic analysis, an elevated hsCRP level (OR = 3.11, 95%CI; 1.27-7.60: P < 0.02) was a significant independent predictor of low CVrr. The results of the present study indicate that an increased serum hsCRP level is significantly associated with reduced CVrr in this general population. It is conceivable that the parasympathetic nerve withdrawal and inflammation could interact with each other, resulting in the progression of atherosclerotic cardiovascular disease. PMID:17268121

  12. Ultrasonically Induced Degradation of Microcystin-LR and -RR: Identification of Products, Effect of pH, Formation and Destruction of Peroxides

    PubMed Central

    SONG, WEIHUA; DE LA CRUZ, ARMAH A.; REIN, KATHLEEN; O'SHEA, KEVIN E.

    2008-01-01

    Microcystins (MCs) are a family of toxic peptides produced by a number of cyanobacteria commonly found in lakes, water reservoirs, and recreational facilities. The increased eutrophication of freshwater supplies has led to an increase in the incidence of cyanobacterial harmful algal blooms and concerns over the public health implications of these toxins in the water supply. Conventional water treatment methods are ineffective at removing low concentrations of cyanotoxins, hence specialized treatment is usually recommended for treatment of contaminated water. In this study, the products of ultrasonically induced degradation of microcystin-LR (MC-LR) and microcystin-RR (MC-RR) were analyzed by LC–MS to elucidate the probable pathways of degradation of these toxins. Results indicate preliminary products of sonolysis of MCs are due to the hydroxyl radical attack on the benzene ring and diene of the Adda peptide residue and cleavage of the Mdha–Ala peptide bond. The effect of pH on the toxin degradation was evaluated since the pH of the solution changes upon ultrasonic irradiation and varies with the water quality of treatable waters. The initial rate of MC-LR degradation is greater at acidic pH and coincides with the change in hydrophobic character of MC-LR as a function of pH. Hydrogen and organic peroxides are formed during ultrasonic irradiation, but can be eliminated by adding Fe(II). The addition of Fe(II) also accelerates the degradation of MC-LR, presumably by promoting the formation of hydroxyl radicals via conversion of ultrasonically produced H2O2. These findings suggest that sonolysis can effectively degrade MCs in drinking water. PMID:16830565

  13. Variable Stars In the Unusual, Metal-Rich Globular Cluster

    NASA Technical Reports Server (NTRS)

    Pritzl, Barton J.; Smith, Horace A.; Catelan, Marcio; Sweigart, Allen V.; Oegerle, William R. (Technical Monitor)

    2002-01-01

    We have undertaken a search for variable stars in the metal-rich globular cluster NGC 6388 using time-series BV photometry. Twenty-eight new variables were found in this survey, increasing the total number of variables found near NGC 6388 to approx. 57. A significant number of the variables are RR Lyrae (approx. 14), most of which are probable cluster members. The periods of the fundamental mode RR Lyrae are shown to be unusually long compared to metal-rich field stars. The existence of these long period RRab stars suggests that the horizontal branch of NGC 6388 is unusually bright. This implies that the metallicity-luminosity relationship for RR Lyrae stars is not universal if the RR Lyrae in NGC 6388 are indeed metal-rich. We consider the alternative possibility that the stars in NGC 6388 may span a range in [Fe/H]. Four candidate Population II Cepheids were also found. If they are members of the cluster, NGC 6388 would be the most metal-rich globular cluster to contain Population II Cepheids. The mean V magnitude of the RR Lyrae is found to be 16.85 +/- 0.05 resulting in a distance of 9.0 to 10.3 kpc, for a range of assumed values of (M(sub V)) for RR Lyrae. We determine the reddening of the cluster to be E(B - V) = 0.40 +/- 0.03 mag, with differential reddening across the face of the cluster. We discuss the difficulty in determining the Oosterhoff classification of NGC 6388 and NGC 6441 due to the unusual nature of their RR Lyrae, and address evolutionary constraints on a recent suggestion that they are of Oosterhoff type II.

  14. Optimization of medium for one-step fermentation of inulin extract from Jerusalem artichoke tubers using Paenibacillus polymyxa ZJ-9 to produce R,R-2,3-butanediol.

    PubMed

    Gao, Jian; Xu, Hong; Li, Qiu-jie; Feng, Xiao-hai; Li, Sha

    2010-09-01

    The medium for one-step fermentation of raw inulin extract from Jerusalem artichoke tubers by Paenibacillus polymyxa ZJ-9 to produce R,R-2,3-butanediol (R,R-2,3-BD) was developed. Inulin, K(2)HPO(4) and NH(4)Cl were found to be the key factors in the fermentation according to the results obtained from the Plackett-Burman experimental design. The optimal concentration range of the three factors was examined by the steepest ascent path, and their optimal concentration was further investigated according to the Box-Behnken design and determined to be 77.14 g/L, 3.09 g/L and 0.93 g/L, respectively. Under the optimal conditions, the concentration of the obtained R,R-2,3-BD was 36.92 g/L, at more than 98% optical purity. Compared with other investigated carbon resources, fermentation of the raw inulin extract afforded the highest yield of R,R-2,3-BD. This process featured one-step fermentation of inulin without further hydrolyzing, which greatly decreased the raw material cost and thus facilitated its practical application. PMID:20452206

  15. Power law behavior of RR-interval variability in healthy middle-aged persons, patients with recent acute myocardial infarction, and patients with heart transplants

    NASA Technical Reports Server (NTRS)

    Bigger, J. T. Jr; Steinman, R. C.; Rolnitzky, L. M.; Fleiss, J. L.; Albrecht, P.; Cohen, R. J.

    1996-01-01

    BACKGROUND. The purposes of the present study were (1) to establish normal values for the regression of log(power) on log(frequency) for, RR-interval fluctuations in healthy middle-aged persons, (2) to determine the effects of myocardial infarction on the regression of log(power) on log(frequency), (3) to determine the effect of cardiac denervation on the regression of log(power) on log(frequency), and (4) to assess the ability of power law regression parameters to predict death after myocardial infarction. METHODS AND RESULTS. We studied three groups: (1) 715 patients with recent myocardial infarction; (2) 274 healthy persons age and sex matched to the infarct sample; and (3) 19 patients with heart transplants. Twenty-four-hour RR-interval power spectra were computed using fast Fourier transforms and log(power) was regressed on log(frequency) between 10(-4) and 10(-2) Hz. There was a power law relation between log(power) and log(frequency). That is, the function described a descending straight line that had a slope of approximately -1 in healthy subjects. For the myocardial infarction group, the regression line for log(power) on log(frequency) was shifted downward and had a steeper negative slope (-1.15). The transplant (denervated) group showed a larger downward shift in the regression line and a much steeper negative slope (-2.08). The correlation between traditional power spectral bands and slope was weak, and that with log(power) at 10(-4) Hz was only moderate. Slope and log(power) at 10(-4) Hz were used to predict mortality and were compared with the predictive value of traditional power spectral bands. Slope and log(power) at 10(-4) Hz were excellent predictors of all-cause mortality or arrhythmic death. To optimize the prediction of death, we calculated a log(power) intercept that was uncorrelated with the slope of the power law regression line. We found that the combination of slope and zero-correlation log(power) was an outstanding predictor, with a

  16. VARIABLE STARS IN THE GLOBULAR CLUSTER NGC 2808

    SciTech Connect

    Kunder, Andrea; Walker, Alistair R.; Stetson, Peter B.; Catelan, Marcio; Amigo, Pia E-mail: mcatelan@astro.puc.cl

    2013-02-01

    The first calibrated broadband BVI time-series photometry is presented for the variable stars in NGC 2808, with observations spanning a range of 28 years. We have also redetermined the variability types and periods for the variable stars identified previously by Corwin et al., revising the number of probable fundamental-mode RR Lyrae variables (RR0) to 11 and the number of first-overtone variables (RR1) to five. Our observations were insufficient to discern the nature of the previously identified RR1 star, V24, and the tentatively identified RR1 star, V13. These two variables are {approx}0.8 mag brighter than the RR Lyrae variables, appear to have somewhat erratic period and/or luminosity changes, and lie inside the RR Lyrae instability strip. Curiously, all but one of the RR Lyrae stars studied in this relatively metal-rich cluster exhibit the Blazhko phenomenon, an effect thought to occur with higher frequency in metal-poor environments. The mean periods of the RR0 and RR1 variables are (P){sub RR0} = 0.56 {+-} 0.01 d and

    {sub RR1} = 0.30 {+-} 0.02 d, respectively, supporting an Oosterhoff I classification of the cluster. On the other hand, the number ratio of RR1-to-RR0-type variables is high, though not unprecedented, for an Oosterhoff I cluster. The RR Lyrae variables have no period shifts at a given amplitude compared to the M3 variables, making it unlikely that these variables are He enhanced. Using the recent recalibration of the RR Lyrae luminosity scale by Catelan and Cortes, a mean distance modulus of (m - M){sub V} = 15.57 {+-} 0.13 mag for NGC 2808 is obtained, in good agreement with that determined here from its type II Cepheid and SX Phoenicis population. Our data have also allowed the discovery of two new candidate SX Phoenicis stars and an eclipsing binary in the blue straggler region of the NGC 2808 color-magnitude diagram.

  17. Homogeneous Photometry. V. The Globular Cluster NGC 4147

    NASA Astrophysics Data System (ADS)

    Stetson, Peter B.; Catelan, M.; Smith, Horace A.

    2005-12-01

    New BVRI broadband photometry and astrometry are presented for the globular cluster NGC 4147, based upon measurements derived from 524 ground-based CCD images mostly either donated by colleagues or retrieved from public archives. We have also reanalyzed five exposures of the cluster obtained with WFPC2 on the Hubble Space Telescope in the F439W and F555W (B and V) filters. We present calibrated color-magnitude and color-color diagrams. Analysis of the color-magnitude diagram reveals morphological properties generally consistent with published metal-abundance estimates for the cluster, and an age typical of other Galactic globular clusters of similar metallicity. We have also redetermined the periods and mean magnitudes for the RR Lyrae variables, including a new c-type variable reported here for the first time. Our data do not show clear evidence for photometric variability in candidate V18, recently reported by Arellano Ferro et al. (2004, Rev. Mex. A&A, 40, 209). These observations also support the nonvariable status of candidates V5, V9, and V15. The union of our light-curve data with those of Newburn (1957, AJ, 62, 197), Mannino (1957, Mem. Soc. Astron. Italiana, 28, 285), and Arellano Ferro et al. (op. cit.) permits the derivation of significantly improved periods. The mean periods and the Bailey period-amplitude diagrams support the classification of the cluster as Oosterhoff I, despite its predominantly blue horizontal branch. The number ratio of c- to ab-type RR Lyrae stars, on the other hand, is unusually high for an Oosterhoff I cluster. The calibrated results have been made available through the first author's Web site. Based in part on archival observations made with ESO telescopes at the La Silla and Paranal Observatory under program ID 60.A-9050(A). 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

  18. HST Snapshot Study of Variable Stars in Globular Clusters: Inner Region of NGC 6441

    NASA Technical Reports Server (NTRS)

    Pritzl, Barton J.; Smith, Horace A.; Stetson, Peter B.; Catelan, Marcio; Sweigart, Allen V.; Layden, Andrew C.; Rich, R. Michael

    2003-01-01

    We present the results of a Hubble Space Telescope snapshot program to survey the inner region of the metal-rich globular cluster NGC 6441 for its variable stars. A total of 57 variable stars was found including 38 RR Lyrae stars, 6 Population II Cepheids, and 12 long period variables. Twenty-four of the RR Lyrae stars and all of the Population II Cepheids were previously undiscovered in ground-based surveys. Of the RR Lyrae stars observed in h s survey, 26 are pulsating in the fundamental mode with a mean period of 0.753 d and 12 are first-overtone mode pulsators with a mean period of 0.365 d. These values match up very well with those found in ground-based surveys. Combining all the available data for NGC 6441, we find mean periods of 0.759 d and 0.375 d for the RRab and RRc stars, respectively. We also find that the RR Lyrae in this survey are located in the same regions of a period-amplitude diagram as those found in ground-based surveys. The overall ratio of RRc to total RR Lyrae is 0.33. Although NGC 6441 is a metal-rich globular cluster and would, on that ground, be expected either to have few RR Lyrae stars, or to be an Oosterhoff type I system, its RR Lyrae more closely resemble those in Oosterhoff type II globular clusters. However, even compared to typical Oosterhoff type II systems, the mean period of its RRab stars is unusually long. We also derived I-band period-luminosity relations for the RR Lyrae stars. Of the six Population II Cepheids, five are of W Virginis type and one is a BL Herculis variable star. This makes NGC 6441, along with NGC 6388, the most metal-rich globular cluster known to contain these types of variable stars. Another variable, V118, may also be a Population II Cepheid given its long period and its separation in magnitude from the RR Lyrae stars. We examine the period-luminosity relation for these Population II Cepheids and compare it to those in other globular clusters and in the Large Magellanic Cloud. We argue that there does

  19. EVIDENCE FOR A MILKY WAY TIDAL STREAM REACHING BEYOND 100 kpc

    SciTech Connect

    Drake, A. J.; Djorgovski, S. G.; Graham, M. J.; Mahabal, A.; Donalek, C.; Williams, R.; Catelan, M.; Torrealba, G.; Prieto, J. L.; Larson, S.; Christensen, E.; Beshore, E.

    2013-03-10

    We present the analysis of 1207 RR Lyrae found in photometry taken by the Catalina Survey's Mount Lemmon telescope. By combining accurate distances for these stars with measurements for {approx}14,000 type-ab RR Lyrae from the Catalina Schmidt telescope, we reveal an extended association that reaches Galactocentric distances beyond 100 kpc and overlaps the Sagittarius stream system. This result confirms earlier evidence for the existence of an outer halo tidal stream resulting from a disrupted stellar system. By comparing the RR Lyrae source density with that expected based on halo models, we find the detection has {approx}8{sigma} significance. We investigate the distances, radial velocities, metallicities, and period-amplitude distribution of the RR Lyrae. We find that both radial velocities and distances are inconsistent with current models of the Sagittarius stream. We also find tentative evidence for a division in source metallicities for the most distant sources. Following prior analyses, we compare the locations and distances of the RR Lyrae with photometrically selected candidate horizontal branch stars and find supporting evidence that this structure spans at least 60 Degree-Sign of the sky. We investigate the prospects of an association between the stream and the unusual globular cluster NGC 2419.

  20. In silico metabolic engineering of Bacillus subtilis for improved production of riboflavin, Egl-237, (R,R)-2,3-butanediol and isobutanol.

    PubMed

    Hao, Tong; Han, Binbin; Ma, Hongwu; Fu, Jing; Wang, Hui; Wang, Zhiwen; Tang, Bincai; Chen, Tao; Zhao, Xueming

    2013-08-01

    Bacillus subtilis is a Gram-positive sporiferous bacterium widely used in a variety of industrial fields as a producer of high-quality vitamins, enzymes and proteins. Many genetic modifications and evolutionary engineering optimisations aiming at obtaining a better performing strain for its products have been studied. As genome-scale metabolic network models have gained significant popularity as effective tools in metabolic phenotype studies, we reconstructed a genome-scale metabolic network of B. subtilis-iBsu1147. The accuracy of iBsu1147 is validated by growth on various carbon sources, single gene knockout and large fragment non-essential gene knockout simulations. The model is used for the in silico metabolic engineering design of reactions over/underexpressed or knockout for increasing the production of four important products of B. subtilis: riboflavin, cellulase Egl-237, (R,R)-2,3-butanediol and isobutanol. The simulation predicted candidate reactions related to the improvement of strain performance on related products. The prediction is partly supported by previously published results. Due to the complexity of the biological system, it is difficult to manually find the factors that are not directly related to the production of the target compounds. The in silico predictions provide more choices for further strain improvement for these products. PMID:23666098

  1. Photometric activity of UX orionis stars and related objects in the near infrared and optical: CO Ori, RR Tau, UX Ori, and VV Ser

    NASA Astrophysics Data System (ADS)

    Shenavrin, V. I.; Rostopchina-Shakhovskaya, A. N.; Grinin, V. P.; Demidova, T. V.; Shakhovskoi, D. N.; Belan, S. P.

    2016-08-01

    This paper continues a study of the photometric activity of UX Ori stars in the optical and near-infrared ( JHKLM bands) initiated in 2000. For comparison, the list of program stars contains two Herbig Ae stars that are photometrically quiet in the optical: MWC480 andHD179218. Fadings ofUXOri stars in the optical ( V band) due to sporadic increases of the circumstellar extinction are also observed in the infrared (IR), but with decreasing amplitude. Two stars, RR Tau and UX Ori, displayed photometric events when V -band fadings were accompanied by an increase in IR fluxes. Among the two Herbig Ae stars that are photometrically quiet in the optical, MWC 480 proved to be fairly active in the IR. Unlike the UX Ori stars, the variation amplitude of MWC 480 increases from the J band to the M band. In the course of the observations, no deep fadings in the IR bands were detected. This indicates that eclipses of the program stars have a local nature, and are due to extinction variations in the innermost regions of the circumstellar disks. The results presented testify to an important role of the alignment of the circumstellar disks relative to the direction towards the observer in determining the observed IR variability of young stars.

  2. Antiallodynic effects of alpha lipoic acid in an optimized RR-EAE mouse model of MS-neuropathic pain are accompanied by attenuation of upregulated BDNF-TrkB-ERK signaling in the dorsal horn of the spinal cord.

    PubMed

    Khan, Nemat; Gordon, Richard; Woodruff, Trent M; Smith, Maree T

    2015-06-01

    Neuropathic pain may affect patients with multiple sclerosis (MS) even in early disease. In an experimental autoimmune encephalomyelitis (EAE)-mouse model of MS, chronic alpha lipoic acid (ALA) treatment reduced clinical disease severity, but MS-neuropathic pain was not assessed. Hence, we investigated the pain-relieving efficacy and mode of action of ALA using our optimized relapsing-remitting (RR)-EAE mouse model of MS-associated neuropathic pain. C57BL/6 mice were immunized with MOG35-55 and adjuvants (Quil A and pertussis toxin) to induce RR-EAE; sham-mice received adjuvants only. RR-EAE mice received subcutaneous ALA (3 or 10 mg kg(-1) day(-1)) or vehicle for 21 days (15-35 d.p.i.; [days postimmunization]); sham-mice received vehicle. Hindpaw hypersensitivity was assessed blinded using von Frey filaments. Following euthanasia (day 35 d.p.i.), lumbar spinal cords were removed for immunohistochemical and molecular biological assessments. Fully developed mechanical allodynia in the bilateral hindpaws of vehicle-treated RR-EAE mice was accompanied by marked CD3(+) T-cell infiltration, microglia activation, and increased brain-derived neurotrophic factor (BDNF)-tyrosine kinase B (TrkB) signaling in the dorsal horn of the lumbar spinal cord. Consequently, phospho-ERK, a marker of central sensitization in neuropathic pain, was upregulated in the spinal dorsal horn. Importantly, hindpaw hypersensitivity was completely attenuated in RR-EAE mice administered ALA at 10 mg kg(-1) day(-1) but not 3 mg kg(-1) day(-1). The antiallodynic effect of ALA (10 mg kg(-1) day(-1)) was associated with a marked reduction in the aforementioned spinal dorsal horn markers to match their respective levels in the vehicle-treated sham-mice. Our findings suggest that ALA at 10 mg kg(-1) day(-1) produced its antiallodynic effects in RR-EAE mice by reducing augmented CD3(+) T-cell infiltration and BDNF-TrkB-ERK signaling in the spinal dorsal horn. PMID:26171221

  3. The evolution of the polycrystalline copper surface, first to Cu(111) and then to Cu(100), at a fixed CO₂RR potential: a study by operando EC-STM.

    PubMed

    Kim, Youn-Geun; Baricuatro, Jack Hess; Javier, Alnald; Gregoire, John Mathew; Soriaga, Manuel P

    2014-12-23

    A study based on operando electrochemical scanning tunneling microscopy (EC-STM) has shown that a polycrystalline Cu electrode held at a fixed negative potential, -0.9 V (vs SHE), in the vicinity of CO2 reduction reactions (CO2RR) in 0.1 M KOH, undergoes stepwise surface reconstruction, first to Cu(111) within 30 min, and then to Cu(100) after another 30 min; no further surface transformations occurred after establishment of the Cu(100) surface. The results may help explain the Cu(100)-like behavior of Cu(pc) in terms of CO2RR product selectivity. They likewise suggest that products exclusive to Cu(100) single-crystal electrodes may be generated through the use of readily available inexpensive polycrystalline Cu electrodes. The study highlights the dynamic nature of heterogeneous electrocatalyst surfaces and also underscores the importance of operando interrogations when structure-composition-reactivity correlations are intended. PMID:25489793

  4. Quantitative Variations of Intracellular Microcystin-LR, -RR and -YR in Samples Collected from Four Locations in Hartbeespoort Dam in North West Province (South Africa) During the 2010/2011 Summer Season

    PubMed Central

    Mbukwa, Elbert A.; Msagati, Titus A.M.; Mamba, Bhekie B.

    2012-01-01

    The Hartbeespoort (HBP) Dam is a reservoir used for agricultural, domestic supply of raw potable water and recreational activities in South Africa’s North-West Province. Eutrophication and cyanobacterial blooms have long been a cause of water-quality problems in this reservoir. The most prevalent bloom-forming species is Microcystis aeruginosa, often producing the toxin microcystin, a hepatotoxin which can negatively impact aquatic animal and human health, and poses a problem for potable water supply. Algal samples were collected monthly from four pre-determined sites in the dam during the summer months (December 2010–March 2011). Intracellular microcystins (MCs) were extracted using SPE C18 cartridges, followed by separation, identification and quantification using LC-ESI-MS techniques. Quantitative variation studies of MCs were conducted with respect to MC congener isolated, sampling site and month. Three main MC congeners (MC-RR, -LR and-YR) were isolated, identified and quantified. In addition, three minor MCs (MC-WR, MC-(H4)YR and (D-Asp3, Dha7)MC-RR were also identified, but were not quantified. The MC dominance followed the order MC-RR>MC-LR>MC-YR across all sites and time. The maximum and minimum concentrations were 268 µg/g and 0.14 µg/g DW for MC-RR and MC-YR, respectively, of the total MCs quantified from this study. One-way ANOVA showed that there were no significant differences between average MC concentrations recorded across months (P = 0.62), there was, however, a marginally-significant difference in concentrations among MC congeners (P = 0.06). ANCOVA revealed a highly significant interaction between sites and MC congeners on MC concentration (P < 0.001). PMID:23202758

  5. Comparison of Polar® RS800G3™ heart rate monitor with Polar® S810i™ and electrocardiogram to obtain the series of RR intervals and analysis of heart rate variability at rest.

    PubMed

    Barbosa, Marianne Penachini da Costa de Rezende; da Silva, Natália Turri; de Azevedo, Fábio Mícolis; Pastre, Carlos Marcelo; Vanderlei, Luiz Carlos Marques

    2016-03-01

    The Polar® RS800G3™ rate monitor was released in the market to replace the Polar® S810i™, and few studies have assessed that the RR series obtained by this equipment is reliable for analysis of heart rate variability (HRV). We compared HRV indexes among the devices Polar® RS800G3™, Polar® S810i™ and eletrocardiogram (ECG) to know whether the series of Polar® RS800G3™ are as reliable as those devices already validated. We analysed data from 30 healthy young adults, male, with an average age of 20·66 ± 1·40 years, which had captured the heart rate beat to beat in the three devices simultaneously with spontaneously breathing, first in the supine position and subsequently sit both for 30 min. The obtained series of RR intervals was used to calculate the indexes of HRV in the time domain (SDNN and RMSSD) and in the frequency domain (LF, HF and LF/HF). There were no significant differences in HRV indexes calculated from series obtained by the three devices, regardless of the position analysed, and a high correlation coefficient was observed. The results suggest that the Polar® RS800G3™ is able to capture series of RR intervals for analysis of HRV indexes as reliable as those obtained by ECG and Polar® S810i™. PMID:25348547

  6. Changes in autonomic function as determined by ECG R-R interval variability in sandal, shoe and leather workers exposed to n-hexane, xylene and toluene.

    PubMed

    Murata, K; Araki, S; Yokoyama, K; Yamashita, K; Okajima, F; Nakaaki, K

    1994-01-01

    To clarify if autonomic nervous system effects might be associated with exposure to organic solvents, 30 sandal, shoe and leather workers exposed to n-hexane, xylene, and toluene, and 25 unexposed controls were examined using the coefficient of variation in electrocardiographic R-R intervals (CVRR), combined with the distribution of nerve conduction velocities (DCV). The C-CVRSA and C-CVMWSA (two component CVs of the CVRR reflecting parasympathetic and sympathetic activities, respectively) were also computed from component spectral powers using autoregressive spectral and component analyses. Concentrations of the metabolites of the solvents in urine samples taken in the morning before work were 0-3.18 (mean 1.39) mg/l for 2,5-hexanedione, 0.10-0.43 (mean 0.19) g/g creatinine (Cn) for methylhippuric acid, and 0.05-2.53 (mean 0.41) g/g Cn for hippuric acid. In the solvent workers, the CVRR and C-CVRSA were reduced significantly when compared with the unexposed controls. The faster velocities of the DCV as well as the sensory median nerve conduction velocity (SCV) were significantly slowed in the solvent-exposed workers. The SCV was significantly correlated with the CVRR and C-CVMWSA among the solvent workers. These data suggest that chronic exposure to some organic solvents may affect cardiac autonomic function (mainly, parasympathetic activity) in addition to faster myelinated fibers of the peripheral nerves. However, the absence of significant dose-effect relations among the solvent workers makes it difficult to definitively attribute the differences to specific solvent exposures. PMID:7715857

  7. Antitumor activity of (R,R')-4-methoxy-1-naphthylfenoterol in a rat C6 glioma xenograft model in the mouse.

    PubMed

    Bernier, Michel; Paul, Rajib K; Dossou, Katina S S; Wnorowski, Artur; Ramamoorthy, Anuradha; Paris, Arnaud; Moaddel, Ruin; Cloix, Jean-François; Wainer, Irving W

    2013-12-01

    (R,R')-4-methoxy-1-naphthylfenoterol (MNF) inhibits cancer cell proliferation in vitro through cell-type specific modulation of β2-adrenergic receptor and/or cannabinoid receptor function. Here, we report an investigation into antitumor activity of MNF in rat C6 glioma cells. The potent antiproliferative action of MNF in these cells (IC50 of ∼1 nmol/L) was refractory to pharmacological inhibition of β2-adrenergic receptor while a synthetic inverse agonist of cannabinoid receptor 1 significantly blocked MNF activity. The antitumor activity of MNF was then assessed in a C6 glioblastoma xenograft model in mice. Three days after subcutaneous implantation of C6 cells into the lower flank of nude mice, these animals were subjected to i.p. injections of saline or MNF (2 mg/kg) for 19 days and tumor volumes were measured over the course of the experiment. Gene expression analysis, quantitative RT-PCR and immunoblot assays were performed on the tumors after treatment. Significant reduction in mean tumor volumes was observed in mice receiving MNF when compared with the saline-treated group. We identified clusters in expression of genes involved in cellular proliferation, as well as molecular markers for glioblastoma that were significantly downregulated in tumors of MNF-treated mice as compared to saline-injected controls. The efficacy of MNF against C6 glioma cell proliferation in vivo and in vitro was accompanied by marked reduction in the expression of cell cycle regulator proteins. This study is the first demonstration of MNF-dependent chemoprevention of a glioblastoma xenograft model and may offer a potential mechanism for its anticancer action in vivo. PMID:25505565

  8. Crystal and molecular structure of four copper(II) ethylenediaminedisuccinates, [Cu{sub 2}(RR,SS-Edds)] . 6H{sub 2}O, Ba{sub 2}[Cu(RR,SS-Edds)](ClO{sub 4}){sub 2} . 8H{sub 2}O, Ba[Cu(SS-HEdds)]ClO{sub 4} . 2H{sub 2}O, and Ba{sub 3}[Cu{sub 2}(RR,SS-Edds){sub 2}](ClO{sub 4}){sub 2} . 6H{sub 2}O

    SciTech Connect

    Polyakova, I. N.; Poznyak, A. L.; Sergienko, V. S.

    2008-11-15

    Four Cu(II) complexes with the RR,SS-Edds{sup 4-} and SS-HEdds{sup 3-} anions are synthesized, and their crystal structures are studied. In the compounds [Cu2(RR,SS-Edds)] . 6H{sub 2}O (I) and Ba2[Cu(RR,SS-Edds)](ClO{sub 4}){sub 2} . 8H{sub 2}O (II), the ligand forms hexacoordinate chelate [Cu(Edds)]{sup 2-} complexes with the N atoms and O atoms of the propionate groups in the equatorial positions and the O atoms of the acetate groups in the axial vertices. In the compounds Ba[Cu(SS-HEdds)]ClO{sub 4} . 2H{sub 2}O (III) and Ba3[Cu2(RR,SS-Edds){sub 2}](ClO{sub 4}){sub 2} . 6H{sub 2}O (IV), one of the propionate arms, the protonated arm in III and the deprotonated arm in IV, does not enter into the coordination sphere of the Cu atom. An acetate arm moves to its position in the equatorial plane, and the free axial vertex is occupied by an O atom of the perchlorate ion. In I-IV, the lengths of the equatorial Cu-N and Cu-O bonds fall in the ranges 1.970-2.014 and 1.921-1.970 A, respectively. The axial Cu-O bonds with the acetate groups and ClO{sub 4}{sup -} anions are elongated to 2.293-2.500 and 2.727-2.992 A, respectively. In structure I, the second Cu atom acts as a counterion forming bonds with the O atoms of two water molecules and three O atoms of the Edds ligands. In II-IV, the Ba{sup 2+} cations are hydrated and bound to the O atoms of the anionic complexes and (except for one of the cations in IV) ClO{sub 4}{sup -} anions. The coordination number of the Ba cations is nine. The structural units in I-IV are connected into layers. In I, an extended system of hydrogen bonds links the layers into a framework. In II and III, the layers are linked only by weak hydrogen bonds, one bond per structural unit. In IV, ClO{sub 4}{sup -} anions are bound to the Ba and Cu atoms of neighboring layers, thus serving as bridges between the layers.

  9. Variable Stars in the Field of the Hydra II Ultra-Faint Dwarf Galaxy

    NASA Astrophysics Data System (ADS)

    Vivas, Anna Katherina; Olsen, Knut A.; Blum, Robert D.; Nidever, David L.; Walker, Alistair R.; Martin, Nicolas; Besla, Gurtina; Gallart, Carme; Van Der Marel, Roeland P.; Majewski, Steven R.; Munoz, Ricardo; Kaleida, Catherine C.; Saha, Abhijit; Conn, Blair; Jin, Shoko

    2016-06-01

    We searched for variable stars in Hydra II, one of the recently discovered ultra-faint dwarf satellites of the Milky Way, using gri time-series obtained with the Dark Energy Camera (DECam) at Cerro Tololo Inter-American Observatory, Chile. We discovered one RR Lyrae star in the galaxy which was used to derive a distance of 154±8 kpc to this system and to re-calculate its absolute magnitude and half-light radius.A comparison with other RR Lyrae stars in ultra-faint systems indicates similar pulsational properties among them, which are different to those found among halo field stars and those in the largest of the Milky Way satellites. We also report the discovery of 31 additional short period variables in the field of view (RR Lyrae, SX Phe, eclipsing binaries, and a likely anomalous cepheid) which are likely not related with Hydra II.

  10. Describing Blazhko light curves with almost periodic functions

    NASA Astrophysics Data System (ADS)

    Benko, J. M.; Szabo, R.

    2016-05-01

    Recent results of photometric space missions such as CoRoT and Kepler showed that the cycle-to-cycle variations of the Blazhko modulation is very frequent. These variations have either multiperiodic or irregular (chaotic/stochastic) nature. We present a mathematical framework in which all of these variations can be handled. We applied the theory of band-limited almost periodic functions to the modulated RR Lyrae light curves. It yields several interesting results: e.g. the harmonics in the Fourier representation of these functions are not exact multiplets of the base frequency or the modulation function depends on the harmonics. Such phenomena are reported for observed RR Lyrae stars as well showing that the almost periodic functions are promising in the mathematical description of the Blazhko RR Lyrae light curves.

  11. Detailed structure and tectonics of the Ninetyeast Ridge near Site ODP 758 (on new geophysical data from KNOX06RR cruise of R/V Roger Revelle)

    NASA Astrophysics Data System (ADS)

    Levchenko, O.; Eisin, A. E.; Ivanenko, A. N.; Marinova, J. G.; Paul, C. F.; Sborshchikov, I. M.; Sager, W. W.

    2008-12-01

    Detailed geophysical survey was carried out during the NSF-funded KNOX06RR cruise of R/V Roger Revelle in July 2007 over the ~70×70 km area near ODP Site 758, the northern Ninetyeast Ridge (NER). In addition to multibeam echo-sounder bathymetry, 3.5 kHz echo-sounder profiles, magnetic, and gravity data, high-resolution multichannel seismic reflection data were collected on eight orthogonal profiles of total length ~270 km. Large NE-trending depressions with complicated horst and graben morphology dominate the whole detailed survey area. The numerous basement faults extend upward into overlying sediments filling out these depressions. Thickness of the sedimentary fill is highly variable due to very rough basement topography, and is up to 800 m maximum. This fill is divided in two clear sedimentary layers: transparent pelagic sediments above and stratified shallow-water ones below. Two high ~400-450 m isometric seamounts extend from the surrounding NER seafloor. High-resolution seismic records show that these igneous basement highs are covered by thin transparent pelagic sediments which hamper the dredging of volcanic rocks. Seismic stratigraphy analyses for sedimentary cover over the seamounts buried slopes suggest that they seem to be recent volcanoes superimposed on the main NER edifice. Both volcanoes are clearly delineated in the constructed map of total anomaly magnetic field. Since water depths are ~2.5 km above these seamounts, the lower edge of the magnetic body in these volcanoes is situated deep at ~7 km under sea level. That appears to represent deep roots of the volcanoes. Preliminary magnetic modeling shows that they were generated during negative chron of the geomagnetic scale rather not long ago and not far from their present location, seeming to confirm the inference that these volcanoes are recent in origin. In general, one may assume a secondary phase of magmatic activity on the NER. It is important to reveal, any recent phase of tectonic and

  12. K - log P is that all?

    NASA Astrophysics Data System (ADS)

    Lub, J.

    2016-05-01

    We investigate the derivation of the K - log P relation for RR Lyrae stars based upon the simplest possible theoretical pulsation equation. Making use of recent theoretical advances due to Marconi et al. (2015) this leads to a direct determination of MV for individual stars, but at the same time we re- discover a simple method using the reddening free and metallicity independent combination W(B,V) = V -3.06(B-V) to do the same. We discuss the relation between the two approaches and compare with other determinations in the liter- ature. A consistent distance of the LMC is derived directly from measurements of its RR Lyrae stars.

  13. Kinematic evidence for an old stellar halo in the Large Magellanic Cloud.

    PubMed

    Minniti, Dante; Borissova, Jura; Rejkuba, Marina; Alves, David R; Cook, Kem H; Freeman, Kenneth C

    2003-09-12

    The oldest and most metal-poor Milky Way stars form a kinematically hot halo, which motivates the two major formation scenarios for our galaxy: extended hierarchical accretion and rapid collapse. RR Lyrae stars are excellent tracers of old and metal-poor populations. We measured the kinematics of 43 RR Lyrae stars in the inner regions of the nearby Large Magellanic Cloud (LMC) galaxy. The velocity dispersion equals 53 +/- 10 kilometers per second, which indicates that a kinematically hot metal-poor old halo also exists in the LMC. This result suggests that our galaxy and smaller late-type galaxies such as the LMC have similar early formation histories. PMID:12970558

  14. TIME-SERIES BVI PHOTOMETRY FOR THE GLOBULAR CLUSTER NGC 6981 {sup ,} {sup ,}

    SciTech Connect

    Amigo, P.; Catelan, M.; Zoccali, M.; Stetson, P. B.; Smith, H. A. E-mail: mzoccali@astro.puc.cl E-mail: Peter.Stetson@nrc-cnrc.gc.ca

    2013-11-01

    We present new BVI photometry of the globular cluster NGC 6981, based mostly on ground-based CCD archival images. We present a new color-magnitude diagram (CMD) that reaches almost four magnitudes below the turn-off level. We performed new derivations of metallicity and morphological parameters of the evolved sequences, in good agreement with the results of previous authors, and obtain a value of [Fe/H] ≅ –1.50 in the new UVES scale. We also identify the cluster's blue straggler population. Comparing the radial distribution of these stars with the red giant branch population, we find that the blue stragglers are more centrally concentrated, as found in previous studies of blue stragglers in globular clusters. Taking advantage of the large field of view covered by our study, we analyzed the surface density profile of the cluster, and find extratidal main sequence stars out to r ≈ 14.'1, or about twice the tidal radius. We speculate that the presence of these stars may be due to tidal disruption in the course of NGC 6981's orbit, in which case tidal tails associated with the cluster may exist. We also take a fresh look at the variable stars in the cluster, recovering all previously known variables, including three SX Phoenicis stars. We also add three previously unknown RR Lyrae (one c-type and two ab-type) to the total census. Finally, comparing our CMD with unpublished data for M3 (NGC 5272), a cluster with a similar metallicity and horizontal branch morphology, we found that both objects are essentially coeval.

  15. Recombination hotspots attenuate the coupled ATPase and translocase activities of an AddAB-type helicase–nuclease

    PubMed Central

    Gilhooly, Neville S.; Dillingham, Mark S.

    2014-01-01

    In all domains of life, the resection of double-stranded DNA breaks to form long 3′-ssDNA overhangs in preparation for recombinational repair is catalyzed by the coordinated activities of DNA helicases and nucleases. In bacterial cells, this resection reaction is modulated by the recombination hotspot sequence Chi. The Chi sequence is recognized in cis by translocating helicase–nuclease complexes such as the Bacillus subtilis AddAB complex. Binding of Chi to AddAB results in the attenuation of nuclease activity on the 3′-terminated strand, thereby promoting recombination. In this work, we used stopped-flow methods to monitor the coupling of adenosine triphosphate (ATP) hydrolysis and DNA translocation and how this is affected by Chi recognition. We show that in the absence of Chi sequences, AddAB translocates processively on DNA at ∼2000 bp s−1 and hydrolyses approximately 1 ATP molecule per base pair travelled. The recognition of recombination hotspots results in a sustained decrease in the translocation rate which is accompanied by a decrease in the ATP hydrolysis rate, such that the coupling between these activities and the net efficiency of DNA translocation is largely unchanged by Chi. PMID:24682829

  16. Rational synthesis of AB-type N-substituted core-functionalized naphthalene diimides (cNDIs).

    PubMed

    Berezin, Andrey A; Sciutto, Andrea; Demitri, Nicola; Bonifazi, Davide

    2015-04-17

    Acid-mediated transformation of tetraethyl 2,6-diethoxynaphthalene-1,4,5,8-tetracarboxylate selectively affords the core-substituted naphthalene-anhydride-ester (cNAE) in quantitative yield. This anhydride can be selectively converted into hetero-N-substituted core-functionalized naphthalene diimides (cNDIs) through sequential condensation reactions in the presence of the precursor amine with very high isolated yields over four steps. The approach can be applied to prepare a large variety of heterocyclic, aromatic, and aliphatic heterodiimides. PMID:25822286

  17. Identification of novel splice site mutation IVS9 + 1(G > A) and novel complex allele G355R/R359X in Type 1 Gaucher patients heterozygous for mutation N370S.

    PubMed

    Hoitsema, Kourtnee; Amato, Dominick; Khan, Aneal; Sirrs, Sandra; Choy, Francis Y M

    2016-09-01

    Gaucher disease is an autosomal recessive lysosomal storage disorder resulting from deficient glucocerebrosidase activity. More than 350 mutations that cause Gaucher disease have been described to date. Novel mutations can potentially provide insight into the glucocerebrosidase structure-function relationship and biochemical basis of the disease. Here, we report the identification of two novel mutations in two unrelated patients with type I (non-neuronopathic) Gaucher disease: 1) a splice site mutation IVS9 + 1G > A; and (2) a complex allele (cis) G355R/R359X. Both patients have a common N370S mutation in the other allele. The splice site mutation results from an intronic base substitution (G to A, c.1328 + 1, g.5005) at the donor splice site of exon and intron 9. The complex allele results from two point mutations in exon 8 of glucocerebrosidase (G to C at c.1180, g.4396, and T to C at c. 1192, g.4408) substituting glycine by arginine (G355R) and arginine by a premature termination (R359X), respectively. In order to demonstrate that G355R/R359X are in cis arrangement, PCR-amplified glucocerebrosidase exon 8 genomic DNA from the patient was cloned into the vector pJET1.2 in Escherichia coli TOP10® strain. Out of the 15 clones that were sequence analyzed, 10 contained the normal allele sequence and 5 contained the complex allele G355R/R359X sequence showing both mutations in cis arrangement. Restriction fragment length polymorphism analysis using Hph1 restriction endonuclease digest was established for the IVS9 + 1G > A mutation for confirmation and efficient identification of this mutation in future patients. Past literature suggests that mutations affecting splicing patterns of the glucocerebrosidase transcript as well as mutations in Gaucher complex alleles are detrimental to enzyme activity. However, compound heterozygosity with N370S, a mild mutation, will lead to a mild phenotype. The cases reported here support these past findings. PMID:27222815

  18. Identification of novel splice site mutation IVS9 + 1(G > A) and novel complex allele G355R/R359X in Type 1 Gaucher patients heterozygous for mutation N370S☆

    PubMed Central

    Hoitsema, Kourtnee; Amato, Dominick; Khan, Aneal; Sirrs, Sandra; Choy, Francis Y.M.

    2016-01-01

    Gaucher disease is an autosomal recessive lysosomal storage disorder resulting from deficient glucocerebrosidase activity. More than 350 mutations that cause Gaucher disease have been described to date. Novel mutations can potentially provide insight into the glucocerebrosidase structure–function relationship and biochemical basis of the disease. Here, we report the identification of two novel mutations in two unrelated patients with type I (non-neuronopathic) Gaucher disease: 1) a splice site mutation IVS9 + 1G > A; and (2) a complex allele (cis) G355R/R359X. Both patients have a common N370S mutation in the other allele. The splice site mutation results from an intronic base substitution (G to A, c.1328 + 1, g.5005) at the donor splice site of exon and intron 9. The complex allele results from two point mutations in exon 8 of glucocerebrosidase (G to C at c.1180, g.4396, and T to C at c. 1192, g.4408) substituting glycine by arginine (G355R) and arginine by a premature termination (R359X), respectively. In order to demonstrate that G355R/R359X are in cis arrangement, PCR-amplified glucocerebrosidase exon 8 genomic DNA from the patient was cloned into the vector pJET1.2 in Escherichia coli TOP10® strain. Out of the 15 clones that were sequence analyzed, 10 contained the normal allele sequence and 5 contained the complex allele G355R/R359X sequence showing both mutations in cis arrangement. Restriction fragment length polymorphism analysis using Hph1 restriction endonuclease digest was established for the IVS9 + 1G > A mutation for confirmation and efficient identification of this mutation in future patients. Past literature suggests that mutations affecting splicing patterns of the glucocerebrosidase transcript as well as mutations in Gaucher complex alleles are detrimental to enzyme activity. However, compound heterozygosity with N370S, a mild mutation, will lead to a mild phenotype. The cases reported here support these past findings. PMID:27222815

  19. THE VARIABLE STAR POPULATION OF THE GLOBULAR CLUSTER B514 IN THE ANDROMEDA GALAXY

    SciTech Connect

    Clementini, Gisella; Contreras, Rodrigo; Federici, Luciana; Cacciari, Carla; Merighi, Roberto; Fusi Pecci, Flavio; Smith, Horace A.; Catelan, Marcio; Marconi, Marcella; Kinemuchi, Karen; Pritzl, Barton J. E-mail: kuehncha@msu.ed E-mail: beers@pa.msu.ed E-mail: marcella@na.astro.i E-mail: kinemuchi@astro.ufl.ed

    2009-10-20

    A rich harvest of RR Lyrae stars has been identified for the first time in B514, a metal-poor ([Fe/H] approx- 1.95 +- 0.10 dex) globular cluster (GC) of the Andromeda galaxy (M31), based on Hubble Space Telescope Wide Field Planetary Camera 2 and Advanced Camera for Surveys time-series observations. We have detected and derived periods for 89 RR Lyrae stars (82 fundamental-mode, RRab, and 7 first-overtone, RRc, pulsators, respectively) among 161 candidate variables identified in the cluster. The average period of the RR Lyrae variables ((Pab) = 0.58 days and (Pc) = 0.35 days, for RRab and RRc pulsators, respectively) and the position in the period-amplitude diagram both suggest that B514 is likely an Oosterhoff type I cluster. This appears to be in disagreement with the general behavior of the metal-poor GCs in the Milky Way, which show instead Oosterhoff type II pulsation properties. The average apparent magnitude of the RR Lyrae stars sets the mean level of the cluster horizontal branch at (V(RR)) = 25.18 +- 0.02 (sigma = 0.16 mag, on 81 stars). By adopting a reddening E(B - V) = 0.07 +- 0.02 mag, the above metallicity and M {sub V} = 0.44 +- 0.05 mag for the RR Lyrae variables of this metallicity, we derive a distance modulus of mu{sub 0} = 24.52 +- 0.08 mag, corresponding to a distance of about 800 +- 30 kpc, based on a value of M {sub V} that sets mu{sub 0}(LMC)=18.52 mag.

  20. Application of the Baade-Wesselink inversion technique to SW Dra, X Ari and U SGR

    NASA Astrophysics Data System (ADS)

    Simon, Norman R.

    1989-03-01

    The Baade-Wesselink inversion technique was applied to three pulsators: the RR(ab) stars SW Dra and X Ari, and the classical Cepheid, U Sgr. A surface brightness parameterization using the V-K color was found to be superior for RR Lyrae stars, while B-V is superior for classical Cepheids. A consistent radius was obtained for SW Dra but not for X Ari.