- ID:
- ivo://CDS.VizieR/J/AJ/142/155
- Title:
- Variable stars photometry from Dome A
- Short Name:
- J/AJ/142/155
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Dome A on the Antarctic plateau is likely one of the best observing sites on Earth thanks to the excellent atmospheric conditions present at the site during the long polar winter night. We present high-cadence time-series aperture photometry of 10000 stars with i<14.5mag located in a 23deg^2^ region centered on the south celestial pole. The photometry was obtained with one of the CSTAR telescopes during 128 days of the 2008 Antarctic winter. We used this photometric data set to derive site statistics for Dome A and to search for variable stars. Thanks to the nearly uninterrupted synoptic coverage, we found six times as many variables as previous surveys with similar magnitude limits. We detected 157 variable stars, of which 55% were unclassified, 27% were likely binaries, and 17% were likely pulsating stars. The latter category includes {delta} Scuti, {gamma} Doradus, and RR Lyrae variables. One variable may be a transiting exoplanet.
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Search Results
- ID:
- ivo://CDS.VizieR/J/MNRAS/478/5091
- Title:
- Variable young stars photometry
- Short Name:
- J/MNRAS/478/5091
- Date:
- 10 Dec 2021 13:53:12
- Publisher:
- CDS
- Description:
- Variability in young stellar objects (YSOs) is one of their primary characteristics. Long-term, multifilter, high-cadence monitoring of large YSO samples is the key to understand the partly unusual light curves that many of these objects show. Here we introduce and present the first results of the HOYS-CAPS citizen science project that aims to perform such monitoring for nearby (d<1kpc) and young (age<10Myr) clusters and star-forming regions, visible from the northern hemisphere, with small telescopes. We have identified and characterized 466 variable (413 confirmed young) stars in eight young, nearby clusters. All sources vary by at least 0.2mag in V, have been observed at least 15 times in V, R, and I in the same night over a period of about 2 yr, and have a Stetson index of larger than 1. This is one of the largest samples of variable YSOs observed over such a time span and cadence in multiple filters. About two-thirds of our sample are classical T-Tauri stars, while the rest are objects with depleted or transition discs. Objects characterized as bursters show by far the highest variability. Dippers and objects whose variability is dominated by occultations from normal interstellar dust or dust with larger grains (or opaque material) have smaller amplitudes. We have established a hierarchical clustering algorithm based on the light-curve properties that allows the identification of the YSOs with the most unusual behaviour and to group sources with similar properties. We discuss in detail the light curves of the unusual objects V2492 Cyg, V350 Cep, and 2MASS J21383981+5708470.
- ID:
- ivo://CDS.VizieR/J/ApJ/707/89
- Title:
- Variation of mid-IR extinction
- Short Name:
- J/ApJ/707/89
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Based on the data obtained from the Spitzer/Galactic Legacy Infrared Midplane Survey Extraordinaire (GLIPMSE) Legacy Program and the Two Micron All Sky Survey (2MASS) project, we derive the extinction in the four IRAC bands, [3.6], [4.5], [5.8], and [8.0]um, relative to the 2MASS Ks band (at 2.16um) for 131 GLIPMSE fields along the Galactic plane within |l|<=65{deg}, using red giants and red clump giants as tracers. As a whole, the mean extinction in the IRAC bands (normalized to the 2MASS Ks band), A_[3.6]_/A_Ks_~0.63+/-0.01, A_[4.5]_/A_Ks_~0.57+/-0.03, A_[5.8]/A_Ks_~0.49+/-0.03, A_[8.0]_/A_Ks_~0.55+/-0.03, exhibits little variation with wavelength (i.e., the extinction is somewhat flat or gray). As far as individual sightline is concerned, however, the wavelength dependence of the mid-infrared interstellar extinction A_{lambda}_/A_Ks_ varies from one sightline to another, suggesting that there may not exist a "universal" IR extinction law.
- ID:
- ivo://CDS.VizieR/J/A+A/463/243
- Title:
- Variations of O-B stars in Mercator observations
- Short Name:
- J/A+A/463/243
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We selected a large sample of O-B stars that were considered as (candidate) slowly pulsating B, beta Cep, and Maia stars after the analysis of their Hipparcos data. We analysed both the Hipparcos data and our new seven passband Geneva data collected for these stars during the first three years of scientific operations of the Mercator telescope. We performed a frequency analysis for 28 targets with more than 50 high-quality Mercator observations to improve their variability classification. We searched for frequencies by using two independent frequency analysis methods and we applied a 3.6 S/N-level criterion to locate the significant peaks in the periodograms. In total we detected 60 frequencies, among which 32 new ones. We classified 21 objects as pulsating variables (7 new confirmed pulsating stars, including 2 hybrid beta Cep/SPB stars), 6 as non-pulsating variables (binaries or spotted stars), and 1 as photometrically constant stars. For the 27 confirmed variable stars in our sample, we give the values and the corresponding standard errors of the accepted frequencies, the amplitudes, the phases, the constant terms, and the residual standard deviations as found in the seven filters of the Geneva photometric system and in the Hp filter of the Hipparcos photometric system by fitting the data with a superposition of sinusoidal models with reference epoch HJD=2450000.
- ID:
- ivo://CDS.VizieR/J/AcA/63/91
- Title:
- V-band light curves of variables in M80
- Short Name:
- J/AcA/63/91
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results of a search for variable stars in the globular cluster M 80. Application of the image subtraction method to the ground-based times-series of CCD frames resulted in finding nine new RR Lyr stars, six of the RRc and three of the RRab type, and four SX Phe variables.
- ID:
- ivo://CDS.VizieR/J/ApJ/756/23
- Title:
- V-band photometric follow-up of RR Lyrae from SEKBO
- Short Name:
- J/ApJ/756/23
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We investigate the steepening of the power-law slope beyond the Galactocentric radius of R~45kpc in the RR Lyrae (RRL) space density distribution found by Keller et al. (2008, Cat. J/ApJ/678/851). They identified 2016 RRL candidates derived from the analysis of archival observations of the Southern Edgeworth-Kuiper Belt Object (SEKBO) survey. Our aim is to verify the completeness of RRLs and ultimately the space density distribution function given by Keller et al. We followed up on a subset of 137 candidates with a range of magnitudes (V~14-20) using the Faulkes Telescope (FT) database and confirmed 57 candidates as real RRLs. A cross-match between SEKBO RRL survey and Sloan Digital Sky Survey Data Release-7 (SDSS DR-7) revealed 272 RRL candidates in common. Applying the color selection criteria proposed by Ivezi\'c et al. (2005AJ....129.1096I) resulted in 193 likely RRLs. The completeness as a function of magnitude was calculated empirically from the combined set of SEKBO RRL candidates from current FT data, SDSS cross-matched data, and the Prior et al. catalog (2009, Cat. J/ApJ/691/306). This resulted in a spatial density distribution characterized by two power laws with a break radius R within a range between 45kpc and 50kpc, similar to the results of Keller et al. We find the power-law slopes for the inner halo as n_inner_=-2.78+/-0.02 and for the outer halo as n_outer_=-5.0+/-0.2.
- ID:
- ivo://CDS.VizieR/J/other/JAD/15.2
- Title:
- VBLUW photometry of eclipsing binary stars
- Short Name:
- J/other/JAD/15.2
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- VBLUW photometric observations of 13 eclipsing binary stars carried out by C.J. van Houten with the Walraven 5-color photometer between 1965 and 1978 are presented together with a first analysis of the orbital periods.
- ID:
- ivo://CDS.VizieR/J/AJ/127/980
- Title:
- vby and BVI photometry of Omega Cen giants
- Short Name:
- J/AJ/127/980
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have obtained photometric observations in a 182arcmin^2 area, 25' to the north of the center of the globular cluster {omega} Centauri. The Stroemgren vby and broadband BI filters were used to obtain measurements for some 2500 stars. Preliminary examinations of parts of the data have been presented previously (Hughes & Wallerstein, 2000, Cat. <J/AJ/119/1225>; Hughes, Wallerstein, & van Leeuwen, 2002, in ASP Conf. Ser. 265, 73). Here we present the complete data set, study the giant branches, and use the B-I color index as a tool for assessing the ages of the populations within {omega} Cen.
- ID:
- ivo://CDS.VizieR/J/A+A/445/617
- Title:
- V823 Cas BV(RI)c differential photometry
- Short Name:
- J/A+A/445/617
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using extended multicolour CCD photometry of the triple-mode radial pulsator V823 Cas we studied the properties of the coupling frequencies invoked by nonlinear processes. Our results support that a resonance connection affects the mode coupling behaviour. The P1/P0 period ratio of V823 Cas has an "out of range" value if compared with the period ratios of the known double mode pulsators, while the P2/P1 period ratio is normal. The periods and period ratios cannot be consistently interpreted without conflict with pulsation and/or evolution models. We describe this failure with the suggestion that at present, the periods of V823 Cas are in a transient, resonance affected state, thus do not reflect the true parameters of the object. The anomalous period change behaviour of the fundamental and second overtone modes supports this idea. We have also raised the possibility that a f0+f2=2f1 resonance may act in triple mode pulsators.
- ID:
- ivo://CDS.VizieR/J/ApJ/660/1186
- Title:
- VCC galaxies classification with SDSS
- Short Name:
- J/ApJ/660/1186
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- From a quantitative analysis of 413 Virgo Cluster early-type dwarf galaxies (dEs) with SDSS imaging data, we find that the dE class can be divided into multiple subpopulations that differ significantly in their morphology and clustering properties. Three dE subclasses are shaped like thick disks and show no central clustering: (1) dEs with disk features like spiral arms or bars, (2) dEs with central star formation, and (3) ordinary, bright dEs that have no or only a weak nucleus.
