- ID:
- ivo://CDS.VizieR/J/AZh/79/510
- Title:
- Galactic orbits of RR Lyrae variable stars
- Short Name:
- J/AZh/79/510
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have used published, high-accuracy, ground-based and satellite proper-motion measurements, a compilation of radial velocities, and photometric distances to compute the spatial velocities and Galactic orbital elements for 174 RR Lyrae (ab) variable stars in the solar neighborhood. The computed orbital elements and published heavy-element abundances are used to study relationships between the chemical, spatial, and kinematic characteristics of nearby RR Lyrae variables. We observe abrupt changes of the spatial and kinematic characteristics at the metallicity [Fe/H]~-0.95 and also when the residual spatial velocities relative to the LSR cross the critical value V_res_~290km/s.
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- ID:
- ivo://CDS.VizieR/J/PASP/111/57
- Title:
- Galactic reddening maps
- Short Name:
- J/PASP/111/57
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Accurate maps of Galactic reddening are important for a number of applications, such as mapping the peculiar velocity field in the nearby universe. Of particular concern are systematic errors which vary slowly as a function of position on the sky, as these would induce spurious bulk flow. We have compared the reddenings of Burstein & Heiles (BH, 1982, Cat. <J/AJ/87/1165>) and those of Schlegel, Finkbeiner, & Davis (1998ApJ...500..525S, SFD) to independent estimates of the reddening, for Galactic latitudes |b|>10{deg}. Our primary source of Galactic reddening estimates comes from comparing the difference between the observed B-V colors of early-type galaxies, and the predicted B-V color determined from the B-V-Mg_2_ relation. We have fitted a dipole to the residuals in order to look for large-scale systematic deviations. There is marginal evidence for a dipolar residual in the comparison between the SFD maps and the observed early-type galaxy reddenings. If this is due to an error in the SFD maps, then it can be corrected with a small (13%) multiplicative dipole term. We argue, however, that this difference is more likely to be due to a small (0.01mag) systematic error in the measured B-V colors of the early-type galaxies. This interpretation is supported by a smaller, independent data set (globular cluster and RR Lyrae stars), which yields a result inconsistent with the early-type galaxy residual dipole. BH reddenings are found to have no significant systematic residuals, apart from the known problem in the region 230{deg}<l<310{deg}, -20{deg}<b<20{deg}.
- ID:
- ivo://CDS.VizieR/J/AJ/144/39
- Title:
- Galactic RRab stars from the GEOS RR Lyr Survey
- Short Name:
- J/AJ/144/39
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We used the GEOS database to study the Blazhko effect of galactic RRab stars. The database is continuously enriched by maxima supplied by amateur astronomers and by a dedicated survey by means of the two TAROT robotic telescopes. The same value of the Blazhko period is observed at different values of the pulsation periods and different values of the Blazhko periods are observed at the same value of the pulsation period. There are clues suggesting that the Blazhko effect is changing from one cycle to the next. The secular changes in the pulsation and Blazhko periods of Z CVn are anticorrelated. The diagrams of magnitudes against phases of the maxima clearly show that the light curves of Blazhko variables can be explained as modulated signals, both in amplitude and in frequency. The closed curves describing the Blazhko cycles in such diagrams have different shapes, reflecting the phase shifts between the epochs of the brightest maximum and the maximum O-C. Our sample shows that both clockwise and counterclockwise directions are possible for similar shapes. The improved observational knowledge of the Blazhko effect, in addition to some peculiarities of the light curves, has yet to be explained by a satisfactory physical mechanism.
- ID:
- ivo://CDS.VizieR/J/MNRAS/396/553
- Title:
- Galactic RR Lyrae data
- Short Name:
- J/MNRAS/396/553
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We use accurate absolute proper motions and Two-Micron All-Sky Survey Ks -band apparent magnitudes for 364 Galactic RR Lyrae variables to determine the kinematical parameters of the Galactic RR Lyrae population and constrain the zero-point of the Ks-band period-luminosity relation for these stars via statistical parallax.
- ID:
- ivo://CDS.VizieR/J/ApJ/766/60
- Title:
- GALEX Time Domain Survey I. UV variable sources
- Short Name:
- J/ApJ/766/60
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the selection and classification of over a thousand ultraviolet (UV) variable sources discovered in ~40deg^2^ of GALEX Time Domain Survey (TDS) NUV images observed with a cadence of 2 days and a baseline of observations of ~3 years. The GALEX TDS fields were designed to be in spatial and temporal coordination with the Pan-STARRS1 Medium Deep Survey, which provides deep optical imaging and simultaneous optical transient detections via image differencing. We characterize the GALEX photometric errors empirically as a function of mean magnitude, and select sources that vary at the 5{sigma} level in at least one epoch. We measure the statistical properties of the UV variability, including the structure function on timescales of days and years. We report classifications for the GALEX TDS sample using a combination of optical host colors and morphology, UV light curve characteristics, and matches to archival X-ray, and spectroscopy catalogs. We classify 62% of the sources as active galaxies (358 quasars and 305 active galactic nuclei), and 10% as variable stars (including 37 RR Lyrae, 53 M dwarf flare stars, and 2 cataclysmic variables). We detect a large-amplitude tail in the UV variability distribution for M-dwarf flare stars and RR Lyrae, reaching up to |{Delta}m|=4.6mag and 2.9mag, respectively. The mean amplitude of the structure function for quasars on year timescales is five times larger than observed at optical wavelengths. The remaining unclassified sources include UV-bright extragalactic transients, two of which have been spectroscopically confirmed to be a young core-collapse supernova and a flare from the tidal disruption of a star by dormant supermassive black hole. We calculate a surface density for variable sources in the UV with NUV<23mag and |{Delta}m|>0.2mag of ~8.0, 7.7, and 1.8deg^-2^ for quasars, active galactic nuclei, and RR Lyrae stars, respectively. We also calculate a surface density rate in the UV for transient sources, using the effective survey time at the cadence appropriate to each class, of ~15 and 52deg^-2^/yr for M dwarfs and extragalactic transients, respectively.
- ID:
- ivo://CDS.VizieR/J/AJ/130/825
- Title:
- GALEX ultraviolet variability catalog
- Short Name:
- J/AJ/130/825
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present version 1.0 of the NASA Galaxy Evolution Explorer (GALEX) ultraviolet variability (GUVV) catalog, which contains information on 84 time-variable and transient sources gained with simultaneous near-ultraviolet (NUV) and far-ultraviolet (FUV) photometric observations. These time-variable sources were serendipitously revealed in the various 1.2{deg} diameter star fields currently being surveyed by the GALEX satellite in two ultraviolet bands (NUV 1750-2750{AA}, FUV 1350-1750{AA}) with limiting AB magnitudes of 23-25. The largest amplitude variable objects currently detected by GALEX are M dwarf flare stars, which can brighten by 5-10mag in both the NUV and FUV bands during short-duration (<500s) outbursts. Other types of large-amplitude ultraviolet variable objects include ab-type RR Lyrae stars, which can vary periodically by 2-5mag in the GALEX FUV band. This first GUVV catalog lists galactic positions and possible source identifications in order to provide the astronomical community with a list of time-variable objects that can now be repeatedly observed at other wavelengths.
- ID:
- ivo://CDS.VizieR/J/A+A/556/A52
- Title:
- {gamma} Dor stars from Kepler
- Short Name:
- J/A+A/556/A52
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The launches of the MOST, CoRoT, and Kepler missions opened up a new era in asteroseismology, the study of stellar interiors via interpretation of pulsation patterns observed at the surfaces of large groups of stars. These space missions deliver a huge amount of high-quality photometric data suitable to study numerous pulsating stars. Our ultimate goal is a detection and analysis of an extended sample of {gamma} Dor-type pulsating stars with the aim to search for observational evidence of non-uniform period spacings and rotational splittings of gravity modes in main-sequence stars typically twice as massive as the Sun. This kind of diagnostic can be used to deduce the internal rotation law and to estimate the amount of rotational mixing in the near core regions. We applied an automated supervised photometric classification method to select a sample of 69 Gamma Doradus ({gamma} Dor) candidate stars. We used an advanced method to extract the Kepler light curves from the pixel data information using custom masks. For 36 of the stars, we obtained high-resolution spectroscopy with the HERMES spectrograph installed at the Mercator telescope. The spectroscopic data are analysed to determine the fundamental parameters like Teff, log g, vsini, and [M/H]. We find that all stars for which spectroscopic estimates of Teff and log g are available fall into the region of the HR diagram, where the {gamma} Dor and {delta} Sct instability strips overlap. The stars cluster in a 700 K window in effective temperature; log g measurements suggest luminosity class IV-V, i.e. sub-giant or main-sequence stars. From the Kepler photometry, we identify 45 {gamma} Dor-type pulsators, 14 {gamma} Dor/{delta} Sct hybrids, and 10 stars, which are classified as "possibly {gamma} Dor/{delta} Sct hybrid pulsators". We find a clear correlation between the spectroscopically derived vsini and the frequencies of independent pulsation modes.
- ID:
- ivo://CDS.VizieR/II/205
- Title:
- GCVS, Vol. V.: Extragalactic Variable Stars
- Short Name:
- II/205
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This catalogue is the last volume of the world-only reference source on all known variable stars. It contains the first Catalogue of variable stars in external galaxies as well as a Catalogue of extragalactic supernovae.
- ID:
- ivo://CDS.VizieR/J/AJ/155/226
- Title:
- Gemini Planet Imager spectra of HR 8799 c/d/e
- Short Name:
- J/AJ/155/226
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We explore Karhunen Loeve Image Projection (KLIP) forward modeling spectral extraction on Gemini Planet Imager coronagraphic data of HR 8799, using PyKLIP, and show algorithm stability with varying KLIP parameters. We report new and re-reduced spectrophotometry of HR 8799 c, d, and e in the H and K bands. We discuss a strategy for choosing optimal KLIP PSF subtraction parameters by injecting simulated sources and recovering them over a range of parameters. The K1/K2 spectra for HR 8799 c and d are similar to previously published results from the same data set. We also present a K-band spectrum of HR 8799 e for the first time and show that our H-band spectra agree well with previously published spectra from the VLT/SPHERE instrument. We show that HR 8799 c and d show significant differences in their H and K spectra, but do not find any conclusive differences between d and e, nor between c and e, likely due to large error bars in the recovered spectrum of e. Compared to M-, L-, and T-type field brown dwarfs, all three planets are most consistent with mid- and late-L spectral types. All objects are consistent with low gravity, but a lack of standard spectra for low gravity limit the ability to fit the best spectral type. We discuss how dedicated modeling efforts can better fit HR 8799 planets' near-IR flux, as well as how differences between the properties of these planets can be further explored.
- ID:
- ivo://CDS.VizieR/II/139B
- Title:
- General Catalog of Variable Stars, 4th Ed. (GCVS4)
- Short Name:
- II/139B
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This data set is the machine-readable version of the fourth edition of the General Catalogue of Variable Stars (Kholopov et al. 1985-1988). The machine version contains the same data as in the first three volumes of the printed catalog, but only the data tables without the textual material (introduction, bibliography, remarks) are included. Modifications to the format of the machine version have been made at the Astronomical Data Center in order to effect a completely homogeneous record structure suitable for full machine processing and sorting. The fourth edition of the General Catalogue of Variable Stars supersedes the third edition (Kukarkin et al. 1969-1970), three supplements (Kukarkin et al. 1971, 1974, 1976) containing data for 5401 new variable stars and improved data for many earlier designated variables, and five namelists (62-66) published in the Information Bulletin of Variable Stars (Kukarkin et al. 1976; Kholopov et al. 1978, 1979, 1981a, 1981b), which included only cross identifications for 2619 new variables. This new edition contains data for 28484 individual objects discovered and named by 1982 and located mainly in the Milky Way galaxy. These data are contained in the first three published volumes. The fourth volume of the fourth edition, published in 1990, contains a table of all variables ordered by right ascension and declination (B1950), a table of variables listed by variability type, and an extensive series of cross-identification tables to alternate designations (see <II/172>). The fifth and final volume will contain data for all presently known variables in external galaxies (including the Magellanic Clouds), extragalactic supernovae, and optically variable quasistellar objects and galactic nuclei (see <II/205>). Data contained in the catalog include star identifier, equatorial position (B1950), annual precession, galactic coordinates, type of variability, maximum and minimum magnitudes, epoch of maximum, period, and spectral type. Since extensive modifications have been made to the record structure of the machine version, users are encouraged to carefully study the brief descriptions given in the document. The list of errors published by Durlevich et al. (1994) has been incorporated in this version
