- ID:
- ivo://CDS.VizieR/J/AJ/147/70
- Title:
- Variability in TAOS I. 58 new variable stars
- Short Name:
- J/AJ/147/70
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Taiwanese-American Occultation Survey project is designed for the detection of stellar occultations by small-size Kuiper Belt Objects, and it has monitored selected fields along the ecliptic plane by using four telescopes with a 3deg^2^ field of view on the sky since 2005. We have analyzed data accumulated during 2005-2012 to detect variable stars. Sixteen fields with observations of more than 100 epochs were examined. We recovered 85 variables among a total of 158 known variable stars in these 16 fields. Most of the unrecovered variables are located in the fields observed less frequently. We also detected 58 variable stars which are not listed in the International Variable Star Index of the American Association of Variable Star Observers. These variable stars are classified as 3 RR Lyrae, 4 Cepheid, 1 {delta} Scuti, 5 Mira, 15 semi-regular, and 27 eclipsing binaries based on the periodicity and the profile of the light curves.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/403/247
- Title:
- Variability in the ROSAT All-Sky Survey
- Short Name:
- J/A+A/403/247
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a systematic search for variability among the ROSAT All-Sky Survey (RASS) X-ray sources. We generated lightcurves for about 30000 X-ray point sources detected sufficiently high above background. For our variability study different search algorithms were developed in order to recognize flares, periods and trends, respectively. The variable X-ray sources were optically identified with counterparts in the SIMBAD, the USNO-A2.0 and NED data bases, but a significant part of the X-ray sources remains without cataloged optical counterparts. A complete list of the 1207 variable sources we found is presented here.
- ID:
- ivo://CDS.VizieR/J/A+A/534/A125
- Title:
- Variability of A- and F-stars from Kepler
- Short Name:
- J/A+A/534/A125
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Kepler spacecraft is providing time series of photometric data with micromagnitude precision for hundreds of A-F type stars. We present a first general characterization of the pulsational behaviour of A-F type stars as observed in the Kepler light curves of a sample of 750 candidate A-F type stars, and observationally investigate the relation between {gamma} Doradus ({gamma} Dor), {delta} Scuti ({delta} Sct), and hybrid stars.
- ID:
- ivo://CDS.VizieR/J/A+A/461/183
- Title:
- Variability of classical T Tauri
- Short Name:
- J/A+A/461/183
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the results of a study the long term variability of Classical T Tauri stars (CTTS) over up to 20 years, characterize it from a set of statistical parameters and discuss its origin. We characterize the long term photometric variations of 49 CTTs with sufficient data for allowing a robust statistical analysis and propose an empirical classification scheme. Several patterns of long term photometric variability are identified. The most common pattern, exhibited by a group of 15 stars which includes T Tau itself, consists of low level variability (with V-amplitude less than 0.4mag) with no significant changes occurring from season to season over many years. A related subgroup of 22 stars exhibit a similar stable long term variability pattern, though with larger amplitudes (up to 1.6mag). Besides these representative groups, we identify three smaller groups of 3-5 stars each of which have distinctive photometric properties. The long term variability of most CTTS is fairly stable and merely reflects shorter term variability due to cold and hot surface spots. Only a small fraction of CTTS undergo significant brightness changes on the long term (months, years), which probably arise from slowly varying circumstellar extinction.
- ID:
- ivo://CDS.VizieR/J/AZh/78/408
- Title:
- Variability of Cyg X-1 in 1994-1998
- Short Name:
- J/AZh/78/408
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Photoelectric UBVR photometry of Cyg X-1 obtained during the coordinated international campaign 'Optical Monitoring of Unique Astrophysical objects', carried out in observatories of CIS countries (Georgia, Kazakhstan, Russia, Uzbekistanin and Ukraine) 1994-1998 is presented. The data are presented as a single set, taking into account systematic differences between individual data sets. In total 2258 UBVR observations were obtained during 407 nights.
- ID:
- ivo://CDS.VizieR/J/PAZh/26/27
- Title:
- Variability of Cyg X-1 (V1357) in 1995-1996
- Short Name:
- J/PAZh/26/27
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Photoelectric UBVR photometry of Cyg X-1 with 1-m Tian'-Shan' and 48-cm Maidanak Observatory reflectors from October 1995 through November 1996 are presented.
- ID:
- ivo://CDS.VizieR/J/MNRAS/415/1061
- Title:
- Variability of FBS blue stellar objects
- Short Name:
- J/MNRAS/415/1061
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A new method for combined calculations of magnitudes based on accurate measurements of POSS1 and POSS2 epoch plates is given. The photometric accuracy of various surveys and catalogs has been estimated and established and statistical weights for each of them have been calculated. To achieve the best possible magnitudes, weighted averaging of data from USNO-A2.0, APM, MAPS, USNO-B1.0, and GSC 2.3.2 catalogs have been used. The rms accuracy of magnitudes achieved for POSS1 is 0.184 mag for B and 0.173 mag for R and for POSS2 is 0.138 mag for B and 0.128 mag for R. We have derived the best POSS1 and POSS2 magnitudes for the FBS blue stellar objects. We have refined the transformation formulae between the POSS1 and POSS2 magnitudes and SDSS ones and standard UBV system. Using these accurate magnitudes, we have estimated the variability of the FBS blue stellar objects and revealed probable and possible variables. We have worked out methods to control and exclude accidental errors that appear in any survey. We have compared and combined our results with those given in NSVS database and obtained better candidates for variability. Having excluded variables, we have combined POSS1 and POSS2 data for the rest of objects to achieve even better magnitudes and colors; the rms being smaller than 0.1 mag both in B and R and for the B-R colors. This approach has been applied to the First Byurakan Survey blue stellar objects containing significant number of white dwarfs, cataclysmic variables, as well as extragalactic objects (quasars, Seyferts, BL Lac objects). Altogether 336 variable objects have been revealed with POSS2-POSS1 >= 3{sigma} of the errors. An electronic table of these objects is given. Candidate variables are divided into 4 classes: extreme, strong, probable and possible variables. For a more reliable sample of variable objects we excluded possible ones from the list and were left with 161 objects. Analyzing radio and X-ray properties of these objects, we have revealed their nature and re-discovered or revealed candidate AGN, CVs, WDs and other objects.
- ID:
- ivo://CDS.VizieR/J/A+A/455/L1
- Title:
- Variability of 5 gravitationally lensed QSOs
- Short Name:
- J/A+A/455/L1
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have searched for microlensing variability in the light curves of five gravitationally lensed quasars with well-determined time delays: SBS 1520+530, FBQ 0951+2635, RX J0911+0551, B1600+434 and HE 2149-2745. By comparing the light curve of the leading image with a suitably time offset light curve of a trailing image we find that two (SBS 1520+530 and FBQ 0951+2635) out of the five quasars have significant long-term (~ years) and short-term (~100-days) brightness variations that may be attributed to microlensing. The short-term variations may be due to nanolenses 10^-4^-10^-3^M_{sun}_, relativistic hot or cold spots in the quasar accretion disks, or coherent microlensing at large optical depth.
- ID:
- ivo://CDS.VizieR/J/ApJ/731/17
- Title:
- Variability of low-mass stars in SDSS Stripe 82
- Short Name:
- J/ApJ/731/17
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a catalog of periodic stellar variability in the "Stripe 82" region of the Sloan Digital Sky Survey. After aggregating and re-calibrating catalog-level data from the survey, we ran a period-finding algorithm (Supersmoother) on all point-source light curves. We used color selection to identify systems that are likely to contain low-mass stars, in particular M dwarfs and white dwarfs. In total, we found 207 candidates, the vast majority of which appear to be in eclipsing binary systems. The catalog described in this paper includes 42 candidate M dwarf/white dwarf pairs, four white dwarf pairs, 59 systems whose colors indicate they are composed of two M dwarfs and whose light-curve shapes suggest they are in detached eclipsing binaries, and 28 M dwarf systems whose light-curve shapes suggest they are in contact binaries. We find no detached systems with periods longer than 3 days, thus the majority of our sources are likely to have experienced orbital spin-up and enhanced magnetic activity.
- ID:
- ivo://CDS.VizieR/J/AJ/134/2099
- Title:
- Variability of point sources in infrared
- Short Name:
- J/AJ/134/2099
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a list of 552 sources with suspected variability, based on a comparison of mid-infrared photometry from the GLIMPSE I and Midcourse Space Experiment (MSX) surveys, which were carried out nearly a decade apart. We were careful to address issues such as the difference in resolution and sensitivity between the two surveys, as well as the differences in the spectral responses of the instruments. We selected only sources where the IRAC 8.0um and MSX 8.28um fluxes differ by more than a factor of 2, in order to minimize contamination from sources where the difference in fluxes at 8um is due to a strong 10um silicate feature. We present a subset of 40 sources for which additional evidence suggests variability, using 2MASS and MIPSGAL data. Based on a comparison with the variability flags in the IRAS and MSX point-source catalogs we estimate that at least a quarter of the 552 sources and at least half of the 40 sources in the subset are truly variable. In addition, we tentatively confirm the variability of one source using multiepoch IRAS LRS spectra. We suggest that most of the sources in our list are likely to be asymptotic giant branch stars.
