- 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.
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- 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.
- 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.
- ID:
- ivo://CDS.VizieR/J/ApJS/250/3
- Title:
- Variable MgII NALs in SDSS DR14
- Short Name:
- J/ApJS/250/3
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Compared to high ionization CIV absorption lines, variable MgII absorption lines are rare. Using spectra from the Sloan Digital Sky Survey, we investigate the variations in MgII narrow absorption lines (NALs) for quasars with multi-epoch observations. We have compiled 8958 MgII NALs in the spectral regions from the red wings of CIV emission lines to the red wings of MgII emission lines. Among these 8958 MgII NALs, 22 variable NALs are detected with |{Delta}W_r_^{lambda}2796^|>=3{sigma}_W_ and with velocity offsets ranging from {upsilon}_r_=522 to 145513km/s. We find that: (1) the detected frequency of MgII NALs with {upsilon}_r_<=10000km/s is significantly larger than the uniformly random value expected for the MgII NALs with {upsilon}_r_>10000km/s, (2) the incidence rates of the variable MgII NALs with {upsilon}_r_<=10000km/s are much larger than those with {upsilon}_r_>10000km/s, (3) the velocity offsets of variable MgII NALs with {upsilon}_r_<=10000km/s are much smaller than the maximum velocities expected from radiation-driven outflows, and (4) the variations of variable MgII NALs with {upsilon}_r_<=10000km/s are obviously correlated with the changes in the quasar radiative output. Therefore, the 16 variable MgII NALs, whose velocities are smaller than the maximum velocities expected from radiation-driven outflows, are likely related to quasar outflows, while the 6 variable MgII NALs, whose velocities are much larger than the maximum velocities expected from radiation-driven outflows, possibly originated in intervening gas. We also find that both the variations and fractional variations in absorption strengths are not related to the velocity offsets of MgII NALs and the time intervals between the two epochs of observations. Also, the fractional variations in absorption strengths are inversely correlated with absorption strengths. In addition, both the associated and intervening MgII NALs can significantly vary on a timescale of days.
- 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.
- ID:
- ivo://CDS.VizieR/J/ApJ/633/638
- Title:
- Variable quasar sample from SDSS
- Short Name:
- J/ApJ/633/638
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- SDSS repeat spectroscopic observations have resulted in multiepoch spectroscopy for 2500 quasars observed more than 50 days apart. From this sample, calibrating against stars observed simultaneously, we identify 315 quasars that have varied significantly between observations (with respect to assumed nonvariable stars observed concurrently). These variable quasars range in redshift from 0.5 to 4.72. This is the first large quasar sample studied spectroscopically for variability and represents a potentially useful sample for future high-redshift reverberation mapping studies. This also marks the first time the precise wavelength dependence of quasar variability has been determined, allowing both the continuum and emission-line variability to be studied.
- 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.
- ID:
- ivo://CDS.VizieR/J/AJ/145/160
- Title:
- Variables in LMC globular clusters. III. Reticulum
- Short Name:
- J/AJ/145/160
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This is the third in a series of papers studying the variable stars in old globular clusters in the Large Magellanic Cloud. The primary goal of this series is to look at how the characteristics and behavior of RR Lyrae stars in Oosterhoff-intermediate systems compare to those of their counterparts in Oosterhoff-I/II systems. In this paper we present the results of our new time-series BVI photometric study of the globular cluster Reticulum. We found a total of 32 variables stars (22 RRab, 4 RRc, and 6 RRd stars) in our field of view. We present photometric parameters and light curves for these stars. We also present physical properties, derived from Fourier analysis of light curves, for some of the RR Lyrae stars. We discuss the Oosterhoff classification of Reticulum and use our results to re-derive the distance modulus and age of the cluster.
- ID:
- ivo://CDS.VizieR/J/AJ/144/186
- Title:
- Variables in LMC globular clusters. II. NGC 1786
- Short Name:
- J/AJ/144/186
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This is the second in a series of papers studying the variable stars in Large Magellanic Cloud globular clusters. The primary goal of this series is to study how RR Lyrae stars in Oosterhoff-intermediate systems compare to their counterparts in Oosterhoff I/II systems. In this paper, we present the results of our new time-series B-V photometric study of the globular cluster NGC 1786. A total of 65 variable stars were identified in our field of view. These variables include 53 RR Lyraes (27 RRab, 18 RRc, and 8 RRd), 3 classical Cepheids, 1 Type II Cepheid, 1 Anomalous Cepheid, 2 eclipsing binaries, 3 Delta Scuti/SX Phoenicis variables, and 2 variables of undetermined type. Photometric parameters for these variables are presented. We present physical properties for some of the RR Lyrae stars, derived from Fourier analysis of their light curves. We discuss several different indicators of Oosterhoff type which indicate that the Oosterhoff classification of NGC 1786 is not as clear cut as what is seen in most globular clusters.
4410. Variables in M33
- ID:
- ivo://CDS.VizieR/J/MNRAS/371/1405
- Title:
- Variables in M33
- Short Name:
- J/MNRAS/371/1405
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have conducted a variability survey of the Local Group galaxy M33, using g', r', and i' observations from 27 nights spanning 17 months, made with the MegaPrime/MegaCam instrument on the 3.6m CFHT telescope (Canada-France-Hawaii Telescope). We identify more than 36000 variable sources with g', r', i'<~24, out of approximately two million point sources in a 1-deg^2^ field of view. This increases the number of known variables in this galaxy by more than a factor of 20. In this paper, we provide a brief description of the data and a general overview of the variable star population which includes more than 1300 candidate variable blue and red supergiant stars, more than 2000 Cepheids, and more than 19000 long-period variable asymptotic giant branch and red giant branch stars.
