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1461. Variability properties of TIC sources with KELT
ID:
ivo://CDS.VizieR/J/AJ/155/39
Title:
Variability properties of TIC sources with KELT
Short Name:
J/AJ/155/39
Date:
21 Oct 2021
Publisher:
CDS
Description:
The Kilodegree Extremely Little Telescope (KELT) has been surveying more than 70% of the celestial sphere for nearly a decade. While the primary science goal of the survey is the discovery of transiting, large-radii planets around bright host stars, the survey has collected more than 10^6^ images, with a typical cadence between 10-30 minutes, for more than four million sources with apparent visual magnitudes in the approximate range 7<V<13. Here, we provide a catalog of 52741 objects showing significant large-amplitude fluctuations likely caused by stellar variability, as well as 62229 objects identified with likely stellar rotation periods. The detected variability ranges in rms-amplitude from ~3 mmag to ~2.3 mag, and the detected periods range from ~0.1 to >~2000 days. We provide variability upper limits for all other ~4000000 sources. These upper limits are principally a function of stellar brightness, but we achieve typical 1{sigma} sensitivity on 30 min timescales down to ~5 mmag at V~8, and down to ~43 mmag at V~13. We have matched our catalog to the TESS Input catalog and the AAVSO Variable Star Index to precipitate the follow-up and classification of each source. The catalog is maintained as a living database on the Filtergraph visualization portal at the URL https://filtergraph.com/kelt_vars.
1462. Variability Sample Catalogue from SOGS
ID:
ivo://CDS.VizieR/J/A+A/503/1023
Title:
Variability Sample Catalogue from SOGS
Short Name:
J/A+A/503/1023
Date:
21 Oct 2021
Publisher:
CDS
Description:
A set of 55000 stars brighter than about B-magnitude 14 and having at least three observations are identified in the Sydney Observatory Galactic Survey, carried out over the years 1892-1932 along the galactic equator section l{in}[275deg,335deg] with galactic latitude b{in}[-7deg,7deg]. Short-term (30min) and long-term (decades) magnitude variations in the data set are analyzed.
1463. Variability Survey in Stock 14 cluster
ID:
ivo://CDS.VizieR/J/AcA/63/339
Title:
Variability Survey in Stock 14 cluster
Short Name:
J/AcA/63/339
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the results of a photometric variability survey in the young open cluster Stock 14 and the surrounding fields. In total, we detected 103 variable stars of which 88 are new discoveries. We confirm short-period, low-amplitude light variations in two eclipsing members of the cluster, HD 101838 and HD 101794. In addition, we find two new {beta} Cep stars of which one, HD 101993, is also a member. The sample of pulsating cluster members is supplemented by one multimode slowly pulsating B-type star and several single-mode candidates of this type. The other pulsating stars in our sample are mostly field stars. In particular, we found 14 {delta} Sct stars including one {gamma} Dor/{delta} Sct hybrid pulsator.
1464. Variability survey of brightest stars
ID:
ivo://CDS.VizieR/J/A+A/598/A108
Title:
Variability survey of brightest stars
Short Name:
J/A+A/598/A108
Date:
21 Oct 2021
Publisher:
CDS
Description:
The stellar evolution theory of massive stars remains uncalibrated with high-precision photometric observational data mainly due to small number of luminous stars monitored from space. Automated all-sky surveys have revealed numerous variable stars but most luminous stars are often overexposed. Targeted campaigns can improve the time base of photometric data for those objects. The aim of this investigation is to study the variability of luminous stars at different time-scales in young open clusters and OB associations. We monitored 22 open clusters and associations from 2011 to 2013 using a 0.25-m telescope. Variable stars were detected by comparing the overall light-curve scatter with measurement uncertainties. Variability was analysed by the light curve feature extraction tool FATS. Periods of pulsating stars were determined using the discrete Fourier transform code SigSpec. We then classified the variable stars based on their pulsation periods and available spectral information. We obtained light curves for more than 20000 sources of which 354 were found to be variable. Amongst them we find 80 eclipsing binaries, 31 {alpha} Cyg, 13 {beta} Cep, 62 Be, 16 slowly pulsating B, 7 Cepheid, 1 {gamma} Doradus, 3 Wolf-Rayet and 63 late-type variable stars. Up to 55% of these stars are potential new discoveries as they are not present in the Variable Star Index (VSX) database. We find the cluster membership fraction for variable stars to be 13% with an upper limit of 35%.
1465. Variable point sources in SDSS stripe 82. I.
ID:
ivo://CDS.VizieR/J/ApJS/186/233
Title:
Variable point sources in SDSS stripe 82. I.
Short Name:
J/ApJS/186/233
Date:
21 Oct 2021
Publisher:
CDS
Description:
We report the first results of a study of variable point sources identified using multi-color timeseries photometry from Sloan Digital Sky Survey (SDSS) Stripe 82, including data from the SDSS-II Supernova Survey, over a span of nearly 10 years (1998-2007). We construct a light-curve catalog of 221842 point sources in the R.A. 0-4hr half of Stripe 82, limited to r=22.0mag, that have at least 10 detections in the ugriz bands and color errors <0.2mag. These sources are then classified by color and by cross matching them to existing SDSS catalogs of interesting objects. Inhomogeneous ensemble differential photometry techniques are used to greatly improve our sensitivity to variability and reduce contamination by sources that appear variable due to large photometric noise or systematic effects caused by non-uniform photometric conditions throughout the survey. We use robust variable identification methods to extract 6520 variable candidates from this data set, resulting in an overall variable fraction of ~2.9% at the level of ~0.05mag variability. Despite the sparse and uneven time sampling of the light-curve data, we discover 143 periodic variables in total. Due to period ambiguity caused by relatively poor phase coverage, we identify a smaller final set of 101 periodic variables with well-determined periods and light curves. Among these are 55 RR Lyrae, 30 eclipsing binary candidates, and 16 high-amplitude Delta Scuti variables. In addition to these objects, we also identify a sample of 2704 variable quasars matched to the SDSS Quasar Catalog, which make up a large fraction of our variable candidates. An additional 2403 quasar candidates are tentatively identified and selected by their non-stellar colors and variability. A sample of 11328 point sources that appear to be nonvariable given the limits of our variability sensitivity is also briefly discussed. Finally, we describe several interesting objects discovered among our eclipsing binary candidates, and illustrate the use of our publicly available light-curve catalog by tracing Galaxy halo substructure with our small sample of RR Lyrae variables.
1466. Variables and dippers in young associations
ID:
ivo://CDS.VizieR/J/MNRAS/498/5972
Title:
Variables and dippers in young associations
Short Name:
J/MNRAS/498/5972
Date:
21 Oct 2021
Publisher:
CDS
Description:
Young associations in star-forming regions are stellar systems that allow us to understand the mechanisms that characterize the stars in their early life and what happens around them. In particular, the analysis of the discs and of the exoplanets around young stars allows us to know the key processes that prevail in their evolution and understand the properties of the exoplanets orbiting older stars. The Transiting Exoplanet Survey Satellite mission is giving us the opportunity to extract and analyse the light curves of association members with high accuracy, but the crowding that affects these regions makes difficult the light curve extraction. In the PATHOS project, cutting-edge tools are used to extract high-precision light curves and identify variable stars and transiting exoplanets in open clusters and associations. In this work, I analysed the light curves of stars in five young (<10Myr) associations, searching for variables and candidate exoplanets. Using the rotational periods of the association members, I constrained the ages of the five stellar systems (~2-10Myr). I searched for dippers, and I investigated the properties of the dust that forms the circumstellar discs. Finally, I searched for transiting signals, finding six strong candidate exoplanets. No candidates with radius Rp<0.9R_J_ have been detected, in agreement with the expectations. The frequency of giant planets resulted to be ~2-3 per cent, higher than that expected for field stars (<1 per cent); the low statistic makes this conclusion not strong, and new investigations on young objects are mandatory to confirm this result.
1467. Variables and Nebulae in Sgr B
ID:
ivo://CDS.VizieR/J/A+AS/76/205
Title:
Variables and Nebulae in Sgr B
Short Name:
J/A+AS/76/205
Date:
21 Oct 2021
Publisher:
CDS
Description:
(no description available)
1468. Variables and Nebulae in Sgr B
ID:
ivo://CDS.VizieR/J/A+AS/90/451
Title:
Variables and Nebulae in Sgr B
Short Name:
J/A+AS/90/451
Date:
21 Oct 2021
Publisher:
CDS
Description:
(no description available)
1469. Variables from 2MASS calibration fields
ID:
ivo://CDS.VizieR/J/ApJS/175/191
Title:
Variables from 2MASS calibration fields
Short Name:
J/ApJS/175/191
Date:
21 Oct 2021
Publisher:
CDS
Description:
The Two Micron All Sky Survey (2MASS) photometric calibration observations cover ~6 square degrees on the sky in 35 "calibration fields", each sampled in nominal photometric conditions between 562 and 3692 times during the 4 years of the 2MASS mission. We compile a catalog of variables from the calibration observations to search for M dwarfs transited by extrasolar planets. We present our methods for measuring periodic and nonperiodic flux variability. From 7554 sources with apparent K_s_ magnitudes between 5.6 and 16.1, we identify 247 variables, including extragalactic variables and 23 periodic variables. We have discovered three M dwarf eclipsing systems, including two candidates for transiting extrasolar planets.
1470. Variables in Centaurus field F170
ID:
ivo://CDS.VizieR/J/A+A/537/A116
Title:
Variables in Centaurus field F170
Short Name:
J/A+A/537/A116
Date:
21 Oct 2021
Publisher:
CDS
Description:
We have used deep V-band and JHKs-band observations to investigate variability and stellar populations near the Galactic plane in Centaurus, and compare the observations with the Galactic model of Besancon. By applying image subtraction technique to a series of over 580 V-band frames taken with the ESO VLT/VIMOS instrument during two contiguous nights in April 2005 we have detected 333 variables among 84,734 stars in the brightness range 12.7<V<26.0mag. Infrared data collected in March 2010 with the new ESO VISTA telescope allowed us to construct deep combined optical-IR colour-magnitude and colour-colour diagrams. All detected variables but four transit candidates are reported for the first time. The majority of the variables are eclipsing/ellipsoidal binaries and delta Scuti-type pulsators. The occurrence rate of eclipsing/ellipsoidal variables reached ~0.28% of all stars. This is very close to the highest fraction of binary systems detected using ground-based data so far (0.30%), but still about four times smaller than the average occurrence rate recently obtained from the Kepler space mission after 44 days of operation. Comparison of the observed Ks vs. V-Ks diagram with a diagram based on the Besancon model shows significant effects of both distance and reddening in the investigated direction of the sky. We demonstrate that the best model indicates presence of absorbing clouds at distances 11-13kpc from the Sun in the minor Carina-Sagittarius Arm.