- ID:
- ivo://CDS.VizieR/J/A+A/640/A128
- Title:
- Cygnus OB2 association NIR light curves
- Short Name:
- J/A+A/640/A128
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of a J, H, and K photometric variability survey of the central 0.78 square degrees of the young OB association Cygnus OB2. We used data observed with the Wide-Field CAMera at the United Kingdom Infrared Telescope in 2007 (spanning 217 days) to investigate the light curves of 5083 low mass candidate members in the association and explore the occurrence and main characteristics of their near-infrared variability. We identified 2529 stars (~50% of the sample) with significant variability with time-scales ranging from days to months. We classified the variable stars into the following three groups according to their light curve morphology: periodic variability (1697 stars), occultation variability (124 stars), and other types of variability (726 stars). We verified that the disk-bearing stars in our sample are significantly more variable in the near-infrared than diskless stars, with a steep increase in the disk-fraction among stars with higher variability amplitude. We investigated the trajectories described by variable stars in the color-space and measured slopes for 335 stars describing linear trajectories. Based on the trajectories in the color-space, we inferred that the sample analyzed is composed of a mix of young stars presenting variability due to hot and cold spots, extinction by circumstellar material, and changes in the disk emission in the near-infrared. We contemplated using the use of near- infrared variability to identify disk-bearing stars and verified that 53.4% of the known disk-bearing stars in our sample could have been identified as such based solely on their variability. We present 18 newly identified disk- bearing stars and 14 eclipsing binary candidates among CygOB2 lower-mass members.
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Search Results
- ID:
- ivo://CDS.VizieR/J/MNRAS/411/1585
- Title:
- CZ Lac multiperiodic Blazhko modulation
- Short Name:
- J/MNRAS/411/1585
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A thorough analysis of the multicolour CCD observations of the RRab-type variable, CZ Lacertae, is presented. The observations were carried out in two consecutive observing seasons in 2004 and 2005 within the framework of the Konkoly Blazhko Survey of bright, northern, short-period RRab variables.
213. Dahlmark variables
- ID:
- ivo://CDS.VizieR/II/238
- Title:
- Dahlmark variables
- Short Name:
- II/238
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Since 1967 32 fields in the Milky Way were observed for variable stars. * New variable stars in Cygnus (1982IBVS.2157....1D) [8/65] Survey of an area of 20{deg}x15{deg} centered at 20h50m, +45{deg} in Cygnus. This area has been followed photographically in two colours during the period 1967 to 1981. As a rule one observation per summer was obtained. * New variable stars in Cassiopeia (1986IBVS.2878....1D) [66/105] Survey in an area 20{deg}x15{deg} centered at 1h06m, +60{deg}01'. Seventeen plate pairs exposed in the period 1967 to 1981 were collected and treated in the same way as described in the previous report. These observations provide approximate B and V magnitudes. In addition, six exposures were obtained in the period August 8 to September 23, 1985 on Technical Pan film. * New variable stars in Cygnus, Lyra and Vulpecula (1993IBVS.3855....1D) [106/185] Area of 20{deg}x15{deg} centred at 19h46m +30{deg}. * New variable stars in Cygnus, Lacerta and Andromeda (1996IBVS.4329....1D) [186/220] Area of 20{deg}x15{deg} centered at 20h40m, +45{deg} (1950). * New variable stars in the northern Milky Way (1997IBVS.4458....1D) [221/280] Area of 20{deg}x15{deg} centered at 22h42m, +60{deg} (1950) * New variable stars in the northern Milky Way (1998IBVS.4642....1D) [281/315] Results of a variable-star search in the 20{deg}x15{deg} area centered at 20h18m, +60{deg} (1950). * New variable stars in Andromeda and Cassiopeia (1999IBVS.4734....1D [316/341] Results of a variable-star search in the 20{deg}x15{deg} area centered at 0h30m, +45{deg} (1950). * New variable stars in Lyra and Cygnus (2000IBVS.4898....1D) [342/366] Results of a variable-star search in the 20{deg}x15{deg} area centered at 19h00m/+45{deg} (1950). * New variable stars along the northern Milky way (2001IBVS.5181....1D) [367/420] Results of a variable-star search in the 20{deg}x15{deg} area centered at 21h22m/+{deg} (1950).
- ID:
- ivo://CDS.VizieR/J/A+AS/106/21
- Title:
- Delta Sct stars: a new revised list
- Short Name:
- J/A+AS/106/21
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- An extensive and up to date list of delta Sct stars is presented. This catalogue is intended to be a comprehensive review of observational characteristics of all the delta Sct stars known until now, including stars contained in earlier catalogues together with other new discovered variables, covering information published until November 1993. Global information in the form of histograms and diagrams are also shown.
- ID:
- ivo://CDS.VizieR/J/MNRAS/475/478
- Title:
- delta Scuti pulsating stars LAMOST views
- Short Name:
- J/MNRAS/475/478
- Date:
- 07 Dec 2021 13:11:57
- Publisher:
- CDS
- Description:
- About 766 {delta} Scuti stars were observed by LAMOST by 2017 June 16. Stellar atmospheric parameters of 525 variables were determined, while spectral types were obtained for all samples. In the paper, those spectroscopic data are catalogued. We detect a group of 131 unusual and cool variable stars (UCVs) that are distinguished from the normal {delta} Scuti stars (NDSTs). On the H-R diagram and the logg-T diagram, the UCVs are far beyond the red edge of pulsational instability trip. Their effective temperatures are lower than 6700K with periods in the range from 0.09 to 0.22d. NDSTs have metallicity close to that of the Sun as expected, while UCVs are slightly metal poor than NDSTs. The two peaks on the distributions of the period and stellar atmospheric parameters are all caused by the existence of UCVs. When those UCVs are excluded, it is discovered that the effective temperature, the gravitational acceleration, and the metallicity all are correlated with the pulsating period for NDSTs and their physical properties and evolutionary states are discussed. Detection of those UCVs indicates that about 25 per cent of the known {delta} Scuti stars may be misclassified. However, if some of them are confirmed to be pulsating stars, they will be a new-type pulsator and their investigations will shed light on theoretical instability domains and on the theories of interacting between the pulsation and the convection of solar-type stars. Meanwhile, 88 {delta} Scuti stars are detected to be the candidates of binary or multiple systems.
216. Delta Scuti stars
- ID:
- ivo://CDS.VizieR/J/A+AS/144/469
- Title:
- Delta Scuti stars
- Short Name:
- J/A+AS/144/469
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- An extensive and up-dated list of {delta} Sct stars is presented here. More than 500 papers, published during the last few years, have been revised and 341 new variables have been added to our last list, six years ago. This catalogue is intended to be a comprehensive review on the observational characteristics of all the {delta} Sct stars known until now, including stars contained in earlier catalogues together with other new discovered variables, covering information published until January 2000. In summary, 636 variables, 1149 references and 182 individual notes are presented in this new list.
- ID:
- ivo://CDS.VizieR/J/MNRAS/471/2491
- Title:
- delta Scuti stars seismic and physical observables
- Short Name:
- J/MNRAS/471/2491
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Asteroseismology is witnessing a revolution, thanks to high-precise asteroseismic space data (MOST, COROT, Kepler, BRITE) and their large ground-based follow-up programs. Those instruments have provided an unprecedented large amount of information, which allows us to scrutinize its statistical properties in the quest for hidden relations among pulsational and/or physical observables. This approach might be particularly useful for stars whose pulsation content is difficult to interpret. This is the case of intermediate-mass classical pulsating stars (i.e. {gamma} Dor, {delta} Scuti, hybrids) for which current theories do not properly predict the observed oscillation spectra. Here, we establish a first step in finding such hidden relations from data mining techniques for these stars. We searched for those hidden relations in a sample of {delta} Scuti and hybrid stars observed by COROT and Kepler (74 and 153, respectively). No significant correlations between pairs of observables were found. However, two statistically significant correlations emerged from multivariable correlations in the observed seismic data, which describe the total number of observed frequencies and the largest one, respectively. Moreover, three different sets of stars were found to cluster according to their frequency density distribution. Such sets are in apparent agreement with the asteroseismic properties commonly accepted for A-F pulsating stars.
- ID:
- ivo://CDS.VizieR/J/A+A/614/A46
- Title:
- delta Scuti stars <Teff>-{nu}max relation
- Short Name:
- J/A+A/614/A46
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- CoRoT and Kepler high-precision photometric data allowed the detection and characterization of the oscillation parameters in stars other than the Sun. Moreover, thanks to the scaling relations, it is possible to estimate masses and radii for thousands of solar-type oscillating stars. Recently, a {Delta}{nu}-{rho} relation has been found for delta Scuti stars. Now, analysing several hundreds of this kind of stars observed with CoRoT and Kepler, we present an empiric relation between their frequency at maximum power of their oscillation spectra and their effective temperature. Such a relation can be explained with the help of the {kappa}-mechanism and the observed dispersion of the residuals is compatible with they being caused by the gravity-darkening effect.
- ID:
- ivo://CDS.VizieR/J/A+A/373/576
- Title:
- Detection of Tycho variables stars
- Short Name:
- J/A+A/373/576
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an original way to detect variable stars in the Tycho photometric observations. A modified Kolmogorov-Smirnov statistical test has been constructed, based on a model of most of the satellite's parameters, leading to the dispersion in the measurements. This allows us to build a treatment taking into account truncated detections and censored measurements, and to search for variability in the faint part of the catalogue. The selection threshold of variable stars has been calibrated to minimize false alarm rate. Reliable results were thus obtained for stars as faint as 11 mag. One thousand and ninety-one suspected variable stars have been listed, 407 of which are already known in Hipparcos, GCVS or NSV, and 684 of which are suspected variable stars to be identified soon.
- ID:
- ivo://CDS.VizieR/J/ApJ/620/961
- Title:
- Diameters of Mira stars in JHK' bands
- Short Name:
- J/ApJ/620/961
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the first spatially resolved observations of a sample of 23 Mira stars simultaneously measured in the near-infrared J, H, and K' bands. The technique used was optical long-baseline interferometry, and we present for each star visibility amplitude measurements as a function of wavelength. We also present characteristic sizes at each spectral band, obtained by fitting the measured visibilities to a simple uniform disk model. This approach reveals the general relation J diameter < H diameter < K' diameter.
