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631. Kinematics of RR Lyr and HB stars in NGP
ID:
ivo://CDS.VizieR/J/MNRAS/375/1381
Title:
Kinematics of RR Lyr and HB stars in NGP
Short Name:
J/MNRAS/375/1381
Date:
21 Oct 2021
Publisher:
CDS
Description:
Radial velocities and proper motions (derived from the GSC-II data base) are given for 38 RR Lyrae (RRL) stars and 79 blue horizontal branch (BHB) stars in a ~200deg^2^ area around the North Galactic Pole (NGP). Both heliocentric (UVW) and galactocentric (VR, Vphi, Vz) space motions are derived for these stars using a homogeneous distance scale consistent with (m-M)0=18.52 for the Large Magellanic Cloud (LMC).
632. Known Galactic field Blazhko stars
ID:
ivo://CDS.VizieR/J/A+A/549/A101
Title:
Known Galactic field Blazhko stars
Short Name:
J/A+A/549/A101
Date:
21 Oct 2021
Publisher:
CDS
Description:
A list of known Galactic field stars exhibiting Blazhko effect containing 242 stars is presented. All the entries including their designations, positions, pulsation, and Blazhko periods were collected from the available literature. The actual values of parameters are given.
633. K2 periodic variables in M35 & NGC2158
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.
634. Ks light curve of 299 SMC new Cepheids
ID:
ivo://CDS.VizieR/J/MNRAS/459/1687
Title:
Ks light curve of 299 SMC new Cepheids
Short Name:
J/MNRAS/459/1687
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present K_s_-band light curves for 299 Cepheids in the Small Magellanic Cloud (SMC) of which 288 are new discoveries that we have identified using multi-epoch near-infrared photometry obtained by the VISTA survey of the Magellanic Clouds system (VMC). The new Cepheids have periods in the range from 0.34 to 9.1d and cover the magnitude interval 12.9<=<K_s_><=17.6mag. Our method was developed using variable stars previously identified by the optical microlensing survey OGLE. We focus on searching new Cepheids in external regions of the SMC for which complete VMC K_s_-band observations are available and no comprehensive identification of different types of variable stars from other surveys exists yet.
635. Ks photometry of LMC RR Lyrae
ID:
ivo://CDS.VizieR/J/A+A/502/505
Title:
Ks photometry of LMC RR Lyrae
Short Name:
J/A+A/502/505
Date:
21 Oct 2021
Publisher:
CDS
Description:
RR Lyrae variable stars are the primary Population II distance indicator. Likewise, the LMC constitutes a key step in the extragalactic distance scale. By combining near-IR photometry and spectroscopically measured metallicities for a homogeneous sample of 50 RR Lyr stars in the Large Magellanic Cloud (LMC), we investigate the metallicity dependence of the period-luminosity relation in the near-infrared (IR), use the newly derived relations to re-derive the distance to the LMC, and compare the distance moduli obtained from RR Lyr and red clump stars.
636. K2 ugri & H{alpha} photometry in the Lagoon Nebula
ID:
ivo://CDS.VizieR/J/AJ/162/101
Title:
K2 ugri & H{alpha} photometry in the Lagoon Nebula
Short Name:
J/AJ/162/101
Date:
14 Mar 2022 06:42:13
Publisher:
CDS
Description:
Space observatories have provided unprecedented depictions of the many variability behaviors typical of low-mass, young stars. However, those studies have so far largely omitted more massive objects (~2M{sun} to 4-5M{sun}) and were limited by the absence of simultaneous, multiwavelength information. We present a new study of young star variability in the ~1-2Myr old, massive Lagoon Nebula region. Our sample encompasses 278 young, late B to K-type stars, monitored with Kepler/K2. Auxiliary u, g, r, i, H{alpha} time-series photometry, simultaneous with K2, was acquired at the Paranal Observatory. We employed this comprehensive data set and archival infrared photometry to determine individual stellar parameters, assess the presence of circumstellar disks, and tie the variability behaviors to inner disk dynamics. We found significant mass-dependent trends in variability properties, with B/A stars displaying substantially reduced levels of variability compared to G/K stars for any light-curve morphology. These properties suggest different magnetic field structures at the surface of early-type and later-type stars. We also detected a dearth of some disk-driven variability behaviors, particularly dippers, among stars earlier than G. This indicates that their higher surface temperatures and more chaotic magnetic fields prevent the formation and survival of inner disk dust structures corotating with the star. Finally, we examined the characteristic variability timescales within each light curve and determined that the day-to-week timescales are predominant over the K2 time series. These reflect distinct processes and locations in the inner disk environment, from intense accretion triggered by instabilities in the innermost disk regions to variable accretion efficiency in the outer magnetosphere.
637. K2 Variability Catalogue II
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.
638. K2 Variable Catalogue
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.
639. KV Vel and TW Crv JHK light curves
ID:
ivo://CDS.VizieR/J/A+A/526/A150
Title:
KV Vel and TW Crv JHK light curves
Short Name:
J/A+A/526/A150
Date:
21 Oct 2021
Publisher:
CDS
Description:
From a number of known post common envelopes binaries (PCEB) only a handful have yet been observed at near-infrared (NIR) wavelengths, and even fewer have modeled NIR light curves. At shorter wavelengths one has access to the cooler and larger components of these systems and has a chance to detect emission from its faint and heavily irradiated atmospheres. By modeling NIR light curves of PCEBs, we intend to constrain their system parameters and study the properties of the system components.
640. KZ Hya times of maximum light
ID:
ivo://CDS.VizieR/J/AJ/135/1958
Title:
KZ Hya times of maximum light
Short Name:
J/AJ/135/1958
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present 109 new times of maximum light of the SX Phoenicis (SX Phe) star KZ Hydrae (KZ Hya) based mainly on our extensive photometric observations for two decades, leading to determination of a general ephemeris combined with the data in the literature.