- ID:
- ivo://CDS.VizieR/J/ApJ/831/11
- Title:
- KIC 9777062 RVs & asteroseismology in NGC6811
- Short Name:
- J/ApJ/831/11
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the analysis of an eccentric, partially eclipsing long-period (P=19.23 days) binary system KIC 9777062 that contains main-sequence stars near the turnoff of the intermediate-age open cluster NGC 6811. The primary is a metal-lined Am star with a possible convective blueshift to its radial velocities, and one star (probably the secondary) is likely to be a {gamma} Dor pulsator. The component masses are 1.603+/-0.006(stat.)+/-0.016(sys.) and 1.419+/-0.003+/-0.008M_{sun}_, and the radii are 1.744+/-0.004+/-0.002 and 1.544+/-0.002+/-0.002R_{sun}_. The isochrone ages of the stars are mildly inconsistent: the age from the mass-radius combination for the primary (1.05+/-0.05+/-0.09Gyr, where the last quote was systematic uncertainty from models and metallicity) is smaller than that from the secondary (1.21+/-0.05+/-0.15Gyr) and is consistent with the inference from the color-magnitude diagram (1.00+/-0.05Gyr). We have improved the measurements of the asteroseismic parameters {Delta}{nu} and {nu}_max_ for helium-burning stars in the cluster. The masses of the stars appear to be larger (or alternately, the radii appear to be smaller) than predicted from isochrones using the ages derived from the eclipsing stars. The majority of stars near the cluster turnoff are pulsating stars: we identify a sample of 28 {delta} Sct, 15 {gamma} Dor, and 5 hybrid types. We used the period-luminosity relation for high-amplitude {delta} Sct stars to fit the ensemble of the strongest frequencies for the cluster members, finding (m-M)_V_=10.37+/-0.03. This is larger than most previous determinations, but smaller than values derived from the eclipsing binary (10.47+/-0.05).
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Search Results
- ID:
- ivo://CDS.VizieR/J/MNRAS/357/497
- Title:
- Kinematics of W UMa-type binaries
- Short Name:
- J/MNRAS/357/497
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The kinematics of 129 W Ursae Majoris type binaries (W UMas) were studied. The sample is heterogeneous with different orbits and physically different components from F to K spectral-type main-sequence stars. The computed U, V, W space velocities indicate that the sample is also heterogeneous in velocity space.
- ID:
- ivo://CDS.VizieR/J/MNRAS/422/2600
- Title:
- KOI-74 radial velocities and fluxes
- Short Name:
- J/MNRAS/422/2600
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a light-curve analysis and radial velocity study of KOI-74, an eclipsing A star + white dwarf binary with a 5.2-d orbit. Aside from new spectroscopy covering the orbit of the system, we used 212-d of publicly available Kepler observations and present the first complete light-curve fitting to these data, modelling the eclipses and transits, ellipsoidal modulation, reflection and Doppler beaming. Markov chain Monte Carlo simulations are used to determine the system parameters and uncertainty estimates.
- ID:
- ivo://CDS.VizieR/J/ApJS/246/15
- Title:
- K2 periodic variables in M35 & NGC2158
- Short Name:
- J/ApJS/246/15
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a catalog of 1143 periodic variables, compiled from our image-subtracted photometric analysis of the K2 Campaign-0 super stamp. This super stamp is centered on the open clusters M35 and NGC2158. Approximately 46% of our periodic variables were previously unreported. Of the catalog variables, we find that 331 are members of M35 and 56 are members of NGC 2158 (P_m_>0.5). Our catalog contains two new transiting exoplanet candidates, both of which orbit field stars. The smaller planet candidate has a radius of 0.35+/-0.04R_J_ and orbits a K dwarf (Kp=15.4mag) with a transit depth of 2.9mmag. The larger planet candidate has a radius of 0.72+/-0.02R_J_ and orbits a late G-type star (Kp=15.7mag) with a transit depth of 2.2mmag. The larger planet candidate may be an unresolved binary or a false alarm. Our catalog includes 44 eclipsing binaries (EBs), including ten new detections. Of the EBs, one is an M35 member and five are NGC 2158 members. Our catalog contains a total of 1097 nontransiting variable stars, including a field {delta} Cepheid exhibiting double mode pulsations, 561 rotational variables, and 251 pulsating variables (primarily {gamma} Doradus and {delta} Scuti types). The periods of our catalog sources range between 43 minutes to 24 days. The known ages of our reported cluster variables will facilitate investigations of a variety of stellar evolutionary processes.
- ID:
- ivo://CDS.VizieR/J/MNRAS/456/2260
- Title:
- K2 Variability Catalogue II
- Short Name:
- J/MNRAS/456/2260
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We are entering an era of unprecedented quantities of data from current and planned survey telescopes. To maximize the potential of such surveys, automated data analysis techniques are required. Here we implement a new methodology for variable star classification, through the combination of Kohonen Self-Organizing Maps (SOMs, an unsupervised machine learning algorithm) and the more common Random Forest (RF) supervised machine learning technique. We apply this method to data from the K2 mission fields 0-4, finding 154 ab-type RR Lyraes (10 newly discovered), 377 {delta} Scuti pulsators, 133 {gamma} Doradus pulsators, 183 detached eclipsing binaries, 290 semidetached or contact eclipsing binaries and 9399 other periodic (mostly spot-modulated) sources, once class significance cuts are taken into account. We present light-curve features for all K2 stellar targets, including their three strongest detected frequencies, which can be used to study stellar rotation periods where the observed variability arises from spot modulation. The resulting catalogue of variable stars, classes, and associated data features are made available online. We publish our SOM code in python as part of the open source pymvpa package, which in combination with already available RF modules can be easily used to recreate the method.
- ID:
- ivo://CDS.VizieR/J/A+A/579/A19
- Title:
- K2 Variable Catalogue
- Short Name:
- J/A+A/579/A19
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have created a catalogue of variable stars found from a search of the publicly available K2 mission data from Campaigns 1 and 0. This catalogue provides the identifiers of 8395 variable stars, including 199 candidate eclipsing binaries with periods up to 60d and 3871 periodic or quasi-periodic objects, with periods up to 20d for Campaign 1 and 15d for Campaign 0. Lightcurves are extracted and detrended from the available data. These are searched using a combination of algorithmic and human classification, leading to a classifier for each object as an eclipsing binary, sinusoidal periodic, quasi periodic, or aperiodic variable. The source of the variability is not identified, but could arise in the non-eclipsing binary cases from pulsation or stellar activity. Each object is cross-matched against variable star related guest observer proposals to the K2 mission, which specifies the variable type in some cases. The detrended lightcurves are also compared to lightcurves currently publicly available. The resulting catalogue is made available online at http://deneb.astro.warwick.ac.uk/phrlbj/k2varcat/, and gives the ID, type, period, semi-amplitude and range of the variation seen. We also make available the detrended lightcurves for each object.
- ID:
- ivo://CDS.VizieR/J/PAZh/25/276
- Title:
- KV Cyg, V435 Cyg, V699 Cyg UBVR photometry
- Short Name:
- J/PAZh/25/276
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The results of a UBVR photometry observations are presented for eclipsing binaries KV Cyg, V435 Cyg and V699 Cyg. Each binary was observed 1989/91 with the 60 cm telescopes at Maidanak Observatory (Uzbekistan).
- ID:
- ivo://CDS.VizieR/J/ApJ/712/1259
- Title:
- LCID project. II. Variables in IC1613
- Short Name:
- J/ApJ/712/1259
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of a new search for variable stars in the Local Group (LG) isolated dwarf galaxy IC 1613, based on 24 orbits of F475W and F814W photometry from the Advanced Camera for Surveys (ACS) on board the Hubble Space Telescope. We detected 259 candidate variables in this field, of which only 13 (all of them bright Cepheids) were previously known. Out of the confirmed variables, we found 90 RR Lyrae stars, 49 classical Cepheids (including 36 new discoveries), and 38 eclipsing binary stars for which we could determine a period. The RR Lyrae include 61 fundamental (RRab) and 24 first-overtone (FO, RRc) pulsators, and five pulsating in both modes simultaneously (RRd). As for the majority of LG dwarfs, the mean periods of the RRab and RRc (0.611 and 0.334 days, respectively) as well as the fraction of overtone pulsators (f_c_=0.28) place this galaxy in the intermediate regime between the Oosterhoff types. From their position on the period-luminosity diagram and light-curve morphology, we can unambiguously classify 25 and 14 Cepheids as fundamental and FO mode pulsators, respectively. Another two are clearly second-overtone Cepheids, the first ones to be discovered beyond the Magellanic Clouds. Among the remaining candidate variables, five were classified as {delta}-Scuti and five as long-period variables. Most of the others are located on the main sequence, the majority of them likely eclipsing binary systems, although some present variations similar to pulsating stars.
- ID:
- ivo://CDS.VizieR/J/AJ/137/507
- Title:
- Light and velocity curves of VZ Cep
- Short Name:
- J/AJ/137/507
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present new V-band differential photometry and radial velocity measurements of the unevolved, 1.18 day period, F+G-type, double-lined eclipsing binary VZ Cep. We determine accurate values for the absolute masses, radii, and effective temperatures.
- ID:
- ivo://CDS.VizieR/J/AJ/133/255
- Title:
- Light-curve and radial velocities of BD+42 2782
- Short Name:
- J/AJ/133/255
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- BD+42 2782 was recently discovered to be a variable star with a W UMa-type, eclipsing-binary light curve. We have obtained the first photoelectric light curves (R_C_, I_C_) and also the first radial velocity curves for this binary.
