- ID:
- ivo://CDS.VizieR/J/A+A/553/A111
- Title:
- Light curves of two NGC6981 variables
- Short Name:
- J/A+A/553/A111
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Two previously unknown variable stars in the crowded central region of the globular cluster NGC 6981 are presented. The observations were made using the electron multiplying CCD (EMCCD) camera at the Danish 1.54m Telescope at La Silla, Chile. The two variables were not previously detected by conventional CCD imaging because of their proximity to a bright star. This discovery demonstrates that EMCCDs are a powerful tool for performing high-precision time-series photometry in crowded fields and near bright stars, especially when combined with difference image analysis.
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- ID:
- ivo://CDS.VizieR/J/other/MmSAI/31.187
- Title:
- Light curves of 12 variables in NGC 6229
- Short Name:
- J/other/MmSAI/31
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Periods and light curves of 12 variable stars of the globular cluster NGC 6229 have been determined. The photographic magnitudes are given for 4 other variables. Observations were obtained at the Asiago observatory, in the years 1956-57-58.
- ID:
- ivo://CDS.VizieR/J/AZh/84/147
- Title:
- Light curves of V838 Mon and V4332 Sgr
- Short Name:
- J/AZh/84/147
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We analyze spectra of V838 Mon and V4332 Sgr taken in 2004-2005 using the 6m telescope of the Special Astrophysical Observatory with the UAGS and SCORPIO spectrographs. We conclude based on spectroscopy combined with archive photographs and modern CCD photometry that both peculiar red novae were binaries prior to their outbursts, and contained blue hot components that exploded. The secondary of V838 Mon is a hot B3V star, and that of V4332 Sgr is a cool M7 star.
- ID:
- ivo://CDS.VizieR/J/ApJ/708/717
- Title:
- Light curve templates of RR Lyrae stars
- Short Name:
- J/ApJ/708/717
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- 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 5-100kpc is highly inhomogeneous. At least 20% of halo stars within 30kpc 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 ~30kpc, 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 RA~2h-3h and DE~0{deg} to be 0.3dex higher ([Fe/H]=-1.2) than that of surrounding halo field stars.
- ID:
- ivo://CDS.VizieR/J/other/PZP/9.3
- Title:
- Light elements for 25 Mira type variables
- Short Name:
- J/other/PZP/9.3
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We could study the variables thanks to the publicly available electronic archives of CCD observations of the ASAS-3 project (Pojmanski, 2002, Cat. <II/264>) and to images of the US Naval Observatory Image and Catalogue Archive (https://www.usno.navy.mil/USNO/astrometry/optical-IR-prod/icas). We recovered the variables NSV 07017 and NSV 07082 suspected by Luyten (1933AN....249..395L); NSV 07106 suspected by Luyten (1933AN....250..259L); NSV 06939, NSV 06975, NSV 06991, NSV 07011, NSV 07025, NSV 07035, NSV 07045, NSV 07047, NSV 07051 and NSV 07062 suspected by Luyten (1934AN....253..135L); NSV 06907, NSV 06946, NSV 07022 and NSV 07083 suspected by Luyten (1935AN....256..325L); NSV 07106 suspected by Luyten (1936AN....258..121L). Finding charts for these suspected variables have never been published.
- ID:
- ivo://CDS.VizieR/V/141
- Title:
- Light-Motion Curve Catalogue (LMCC) in Stripe 82
- Short Name:
- V/141
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a public archive of light-motion curves in Sloan Digital Sky Survey (SDSS) Stripe 82, covering 99{deg} in right ascension (20.7h to 3.3h) and spanning 2.52{deg} in declination (-1.26 to 1.26), for a total sky area of about 249sq.deg. Stripe 82 has been repeatedly monitored in the u, g, r, i and z bands over a seven-year baseline. Objects are cross-matched between runs, taking into account the effects of any proper motion. The resulting catalogue contains almost 4million light-motion curves of stellar objects and galaxies. The photometry are recalibrated to correct for varying photometric zeropoints, achieving ~20mmag and 30mmag root-mean-square (RMS) accuracy down to 18mag in the g, r, i and z bands for point sources and extended sources, respectively. The astrometry are recalibrated to correct for inherent systematic errors in the SDSS astrometric solutions, achieving 32mas and 35mas RMS accuracy down to 18mag for point sources and extended sources, respectively. For each light-motion curve, 229 photometric and astrometric quantities are derived and stored in a higher-level catalogue. On the photometric side, these include mean exponential and PSF magnitudes along with uncertainties, RMS scatter, {chi}^2^ per degree of freedom, various magnitude distribution percentiles, object type (stellar or galaxy), and eclipse, Stetson and Vidrih variability indices. On the astrometric side, these quantities include mean positions, proper motions as well as their uncertainties and {chi}^2^ per degree of freedom. The here presented light-motion curve catalogue is complete down to r~21.5mag and is at present the deepest large-area photometric and astrometric variability catalogue available.
- ID:
- ivo://CDS.VizieR/J/AJ/146/21
- Title:
- LINEAR. II. Catalog of RR Lyrae stars
- Short Name:
- J/AJ/146/21
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a sample of ~5000 RR Lyrae stars selected from the recalibrated LINEAR data set and detected at heliocentric distances between 5kpc and 30kpc over ~8000 deg^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 ~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.
- ID:
- ivo://CDS.VizieR/J/AJ/146/101
- Title:
- LINEAR. III. Catalog of periodic variables
- Short Name:
- J/AJ/146/101
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We describe the construction of a highly reliable sample of ~7000 optically faint periodic variable stars with light curves obtained by the asteroid survey LINEAR across 10000deg^2^ of the northern sky. The majority of these variables have not been cataloged yet. The sample flux limit is several magnitudes fainter than most other wide-angle surveys; the photometric errors range from ~0.03mag at r=15 to ~0.20mag at r=18. Light curves include on average 250 data points, collected over about a decade. Using Sloan Digital Sky Survey (SDSS) based photometric recalibration of the LINEAR data for about 25 million objects, we selected ~200000 most probable candidate variables with r<17 and visually confirmed and classified ~7000 periodic variables using phased light curves. The reliability and uniformity of visual classification across eight human classifiers was calibrated and tested using a catalog of variable stars from the SDSS Stripe 82 region and verified using an unsupervised machine learning approach. The resulting sample of periodic LINEAR variables is dominated by 3900 RR Lyrae stars and 2700 eclipsing binary stars of all subtypes and includes small fractions of relatively rare populations such as asymptotic giant branch stars and SX Phoenicis stars. We discuss the distribution of these mostly uncataloged variables in various diagrams constructed with optical-to-infrared SDSS, Two Micron All Sky Survey, and Wide-field Infrared Survey Explorer photometry, and with LINEAR light-curve features. We find that the combination of light-curve features and colors enables classification schemes much more powerful than when colors or light curves are each used separately. An interesting side result is a robust and precise quantitative description of a strong correlation between the light-curve period and color/spectral type for close and contact eclipsing binary stars ({beta} Lyrae and W UMa): as the color-based spectral type varies from K4 to F5, the median period increases from 5.9hr to 8.8hr. These large samples of robustly classified variable stars will enable detailed statistical studies of the Galactic structure and physics of binary and other stars and we make these samples publicly available.
- ID:
- ivo://CDS.VizieR/J/A+A/310/164
- Title:
- Line profile variations in eta Ori
- Short Name:
- J/A+A/310/164
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Eta Orionis (HD35411) is a multiple system which consists of at least four early B-type stars. In the present paper we focus on the double-lined spectroscopic eclipsing pair Aab, and in particular on component Ab, which is a remarkable intrinsically variable star. The presence of this variable in an eclipsing system enables us to determine accurately its mass, radius, inclination angle and rotation period.
- ID:
- ivo://CDS.VizieR/J/MNRAS/437/2307
- Title:
- LMC anomalous Cepheid Ks light curves
- Short Name:
- J/MNRAS/437/2307
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The VISTA near-infrared YJKs survey of the Magellanic Clouds System (VMC, PI M.-R. L. Cioni) is collecting deep Ks-band time-series photometry of the pulsating variable stars hosted in the system formed by the two Magellanic Clouds and the Bridge connecting them. In this paper, we present for the first time Ks-band light curves for anomalous Cepheid (AC) variables. In particular, we have analysed a sample of 48 Large Magellanic Cloud ACs, for which identification and optical magnitudes were obtained from the OGLE III and IV catalogues. The VMC Ks-band light curves for ACs are well sampled, with the number of epochs ranging from 8 to 16, and allowing us to obtain very precise mean Ks magnitudes with errors on average of the order of 0.01mag. The <Ks> values were used to build the first period-luminosity and period-Wesenheit relations in the near-infrared for fundamental mode and first overtone ACs. At the same time we exploited the optical (V, I) OGLE data to build accurate period-luminosity, period-luminosity-colour and period-Wesenheit relations both for fundamental mode and first overtone ACs. For the first time, these relations were derived from a sample of pulsators which uniformly cover the whole AC instability strip. The application of the optical period-Wesenheit relation to a sample of dwarf galaxies hosting a significant population of ACs revealed that this relation is a valuable tool for deriving distances within the Local Group. Due to its lower dispersion, we expect the Ks period-Wesenheit relations first derived in this paper to represent a valuable tool for measuring accurate distances to galaxies hosting ACs when more data in near-infrared filters become available.
