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391. JHKs photometry of T2Cs in globular clusters
ID:
ivo://CDS.VizieR/J/MNRAS/370/1979
Title:
JHKs photometry of T2Cs in globular clusters
Short Name:
J/MNRAS/370/1979
Date:
21 Oct 2021
Publisher:
CDS
Description:
We report the result of our near-infrared observations (JHKs) for type II Cepheids (including possible RV Tau stars) in galactic globular clusters. We detected variations of 46 variables in 26 clusters (10 new discoveries in seven clusters) and present their light curves. Their periods range from 1.2d to over 80d. They show a well-defined period-luminosity relation at each wavelength. Two type II Cepheids in NGC 6441 also obey the relation if we assume the horizontal branch stars in NGC 6441 are as bright as those in metal-poor globular clusters in spite of the high metallicity of the cluster.
392. JHKs photometry of VVV RR Lyrae stars
ID:
ivo://CDS.VizieR/J/ApJ/857/54
Title:
JHKs photometry of VVV RR Lyrae stars
Short Name:
J/ApJ/857/54
Date:
21 Oct 2021
Publisher:
CDS
Description:
RR Lyrae stars (RRLs) are tracers of the Milky Way's fossil record, holding valuable information on its formation and early evolution. Owing to the high interstellar extinction endemic to the Galactic plane, distant RRLs lying at low Galactic latitudes have been elusive. We attained a census of 1892 high-confidence RRLs by exploiting the near-infrared photometric database of the VVV survey's disk footprint spanning ~70{deg} of Galactic longitude, using a machine-learned classifier. Novel data-driven methods were employed to accurately characterize their spatial distribution using sparsely sampled multi-band photometry. The RRL metallicity distribution function (MDF) was derived from their K_s_-band light-curve parameters using machine-learning methods. The MDF shows remarkable structural similarities to both the spectroscopic MDF of red clump giants and the MDF of bulge RRLs. We model the MDF with a multi-component density distribution and find that the number density of stars associated with the different model components systematically changes with both the Galactocentric radius and vertical distance from the Galactic plane, equivalent to weak metallicity gradients. Based on the consistency with results from the ARGOS survey, three MDF modes are attributed to the old disk populations, while the most metal-poor RRLs are probably halo interlopers. We propose that the dominant [Fe/H] component with a mean of -1dex might correspond to the outskirts of an ancient Galactic spheroid or classical bulge component residing in the central Milky Way. The physical origins of the RRLs in this study need to be verified by kinematical information.
393. JHKs, WISE and Spitzer data of Galactic Cepheids
ID:
ivo://CDS.VizieR/J/ApJ/852/78
Title:
JHKs, WISE and Spitzer data of Galactic Cepheids
Short Name:
J/ApJ/852/78
Date:
21 Oct 2021
Publisher:
CDS
Description:
Classical Cepheids are well-known and widely used distance indicators. As distance and extinction are usually degenerate, it is important to develop suitable methods to robustly anchor the distance scale. Here, we introduce a near-infrared optimal distance method to determine both the extinction values of and distances to a large sample of 288 Galactic classical Cepheids. The overall uncertainty in the derived distances is less than 4.9%. We compare our newly determined distances to the Cepheids in our sample with previously published distances to the same Cepheids with Hubble Space Telescope parallax measurements and distances based on the IR surface brightness method, Wesenheit functions, and the main-sequence fitting method. The systematic deviations in the distances determined here with respect to those of previous publications is less than 1%-2%. Hence, we constructed Galactic mid-IR period-luminosity (PL) relations for classical Cepheids in the four Wide-Field Infrared Survey Explorer (WISE) bands (W1, W2, W3, and W4) and the four Spitzer Space Telescope bands ([3.6], [4.5], [5.8], and [8.0]). Based on our sample of hundreds of Cepheids, the WISE PL relations have been determined for the first time; their dispersion is approximately 0.10mag. Using the currently most complete sample, our Spitzer PL relations represent a significant improvement in accuracy, especially in the [3.6] band which has the smallest dispersion (0.066mag). In addition, the average mid-IR extinction curve for Cepheids has been obtained: A_W1_/A_Ks_~0.560, A_W2_/A_Ks_~0.479, A_W3_/A_Ks_~0.507, A_W4_/A_Ks_~0.406, A_[3.6]_/A_Ks_~0.481, A_[4.5]_/A_Ks_~0.469, A_[5.8]_/A_Ks_~0.427, and A_[8.0]_/A_Ks_~0.427mag.
394. JHK variable stars in M33
ID:
ivo://CDS.VizieR/J/MNRAS/411/263
Title:
JHK variable stars in M33
Short Name:
J/MNRAS/411/263
Date:
21 Oct 2021
Publisher:
CDS
Description:
We have conducted a near-infrared monitoring campaign at the UK InfraRed Telescope (UKIRT), of the Local Group spiral galaxy M 33 (Triangulum). The main aim was to identify stars in the very final stage of their evolution, and for which the luminosity is more directly related to the birth mass than the more numerous less-evolved giant stars that continue to increase in luminosity. The most extensive dataset was obtained in the K-band with the UIST instrument for the central 4'x4' (1kpc^2^) --- this contains the nuclear star cluster and inner disc. These data, taken during the period 2003-2007, were complemented by J- and H-band images. Photometry was obtained for 18,398 stars in this region; of these, 812 stars were found to be variable, most of which are Asymptotic Giant Branch (AGB) stars. Our data were matched to optical catalogues of variable stars and carbon stars, and to mid-infrared photometry from the Spitzer Space Telescope. In this first of a series of papers, we present the methodology of the variability survey and the photometric catalogue, which is made publicly available at the Centre de Donnees astronomiques de Strasbourg (CDS), and discuss the properties of the variable stars. Most dusty AGB stars had not been previously identified in optical variability surveys, and our survey is also more complete for these types of stars than the Spitzer survey.
395. K2 Campaign 9 added events
ID:
ivo://CDS.VizieR/J/PASP/128/L4401
Title:
K2 Campaign 9 added events
Short Name:
J/PASP/128/L4401
Date:
21 Oct 2021
Publisher:
CDS
Description:
K2's Campaign 9 (K2C9) will conduct a ~3.7 deg^2^ survey toward the Galactic bulge from 2016 April 22 through July 2 that will leverage the spatial separation between K2 and the Earth to facilitate measurement of the microlens parallax {pi}_E_ for >~170 microlensing events. These will include several that are planetary in nature as well as many short-timescale microlensing events, which are potentially indicative of free-floating planets (FFPs). These satellite parallax measurements will in turn allow for the direct measurement of the masses of and distances to the lensing systems. In this article we provide an overview of the K2C9 space- and ground-based microlensing survey. Specifically, we detail the demographic questions that can be addressed by this program, including the frequency of FFPs and the Galactic distribution of exoplanets, the observational parameters of K2C9, and the array of resources dedicated to concurrent observations. Finally, we outline the avenues through which the larger community can become involved, and generally encourage participation in K2C9, which constitutes an important pathfinding mission and community exercise in anticipation of WFIRST.
396. K2 Campaign 2: young disk-bearing stars in Sco & Oph
ID:
ivo://CDS.VizieR/J/AJ/156/71
Title:
K2 Campaign 2: young disk-bearing stars in Sco & Oph
Short Name:
J/AJ/156/71
Date:
21 Oct 2021
Publisher:
CDS
Description:
The K2 Mission has photometrically monitored thousands of stars at high precision and cadence in a series of ~80-day campaigns focused on sections of the ecliptic plane. During its second campaign, K2 targeted over 1000 young stellar objects (YSOs) in the ~1-3 Myr {rho} Ophiuchus and 5-10 Myr Upper Scorpius regions. From this set, we have carefully vetted photometry from WISE and Spitzer to identify those YSOs with infrared excess indicative of primordial circumstellar disks. We present here the resulting comprehensive sample of 288 young disk-bearing stars from B through M spectral types and analysis of their associated K2 light curves. Using statistics of periodicity and symmetry, we categorize each light curve into eight different variability classes, notably including "dippers" (fading events), "bursters" (brightening events), stochastic, and quasi-periodic types. Nearly all (96%) of disk-bearing YSOs are identified as variable at 30-minute cadence with the sub-1% precision of K2. Combining our variability classifications with (circum)stellar properties, we find that the bursters, stochastic sources, and the largest amplitude quasi-periodic stars have larger infrared colors, and hence stronger circumstellar disks. They also tend to have larger H{alpha} equivalent widths, indicative of higher accretion rates. The dippers, on the other hand, cluster toward moderate infrared colors and low H{alpha}. Using resolved disk observations, we further find that the latter favor high inclinations, except for a few notable exceptions with close to face-on disks. These observations support the idea that YSO time-domain properties are dependent on several factors, including accretion rate and view angle.
397. Kepler compact pulsator candidates
ID:
ivo://CDS.VizieR/J/MNRAS/414/2860
Title:
Kepler compact pulsator candidates
Short Name:
J/MNRAS/414/2860
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present results from the final 6 months of a survey to search for pulsations in white dwarfs (WDs) and hot subdwarf stars with the Kepler spacecraft. Spectroscopic observations are used to separate the objects into accurate classes, and we explore the physical parameters of the subdwarf B (sdB) stars and white dwarfs in the sample. From the Kepler photometry and our spectroscopic data, we find that the sample contains five new pulsators of the V1093 Her type, one AM CVn type cataclysmic variable and a number of other binary systems.
398. Kepler cycle 1 observations of low-mass stars
ID:
ivo://CDS.VizieR/J/AJ/143/4
Title:
Kepler cycle 1 observations of low-mass stars
Short Name:
J/AJ/143/4
Date:
21 Oct 2021
Publisher:
CDS
Description:
We have analyzed Kepler light curves for 849 stars with Teff<=5200K from our Cycle 1 Guest Observer program. We identify six new eclipsing binaries, one of which has an orbital period of 29.91 days and two of which are probably W UMa variables. In addition, we identify a candidate "warm Jupiter" exoplanet. We further examine a subset of 670 sources for variability. Of these objects, 265 stars clearly show periodic variability that we assign to rotation of the low-mass star. At the photometric precision level provided by Kepler, 251 of our objects showed no evidence for variability. We were unable to determine periods for 154 variable objects. We find that 79% of stars with Teff<=5200K are variable. The rotation periods we derive for the periodic variables span the range 0.31days<=Prot<=126.5days. A considerable number of stars with rotation periods similar to the solar value show activity levels that are 100 times higher than the Sun.
399. Kepler Data Search
ID:
ivo://archive.stsci.edu/kepler
Title:
Kepler Data Search
Short Name:
Kepler CS
Date:
22 Jul 2020 21:17:20
Publisher:
Space Telescope Science Institute Archive
Description:
Launched in 2009, the Kepler Mission is surveying a region of our galaxy to determine what fraction of stars in our galaxy have planets and measure the size distribution of those exoplanets. Although Kepler completed its primary mission to determine the fraction of stars that have planets in 2013, it is continuing the search, using a more limited survey mode, under the new name K2. This service is the main Kepler data search.
400. Kepler Data Search
ID:
ivo://archive.stsci.edu/kepler_ktc
Title:
Kepler Data Search
Short Name:
KTC
Date:
22 Jul 2020 21:12:32
Publisher:
Space Telescope Science Institute Archive
Description:
This interface joins the Kepler Target Catalog (KTC) with other tables to allow users to access the Kepler data archive. Observed Kepler targets are included with their associated data set names. Since most of the Kepler light curve data is still proprietary, public data can be found by searching for release dates earlier than todays date.