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Start Over Subject infrared photometry Subject multiple stars Subject proper motions
1. Ages & masses for GPS1 WD-MS binary systems
ID:
ivo://CDS.VizieR/J/ApJ/870/9
Title:
Ages & masses for GPS1 WD-MS binary systems
Short Name:
J/ApJ/870/9
Date:
21 Oct 2021
Publisher:
CDS
Description:
Observational tests of stellar and Galactic chemical evolution call for the joint knowledge of a star's physical parameters, detailed element abundances, and precise age. For cool main-sequence (MS) stars the abundances of many elements can be measured from spectroscopy, but ages are very hard to determine. The situation is different if the MS star has a white dwarf (WD) companion and a known distance, as the age of such a binary system can then be determined precisely from the photometric properties of the cooling WD. As a pilot study for obtaining precise age determinations of field MS stars, we identify nearly 100 candidates for such wide binary systems: a faint WD whose Gaia-PS1-SDSS (GPS1) proper motion (Tian+ 2017, I/343) matches that of a brighter MS star in Gaia/TGAS (Gaia Collaboration 2016, I/337) with a good parallax ({sigma}_{rho}_/{rho}=<0.05). We model the WD's multi-band photometry with the BASE-9 code using this precise distance (assumed to be common for the pair) and infer ages for each binary system. The resulting age estimates are precise to =<10% (=<20%) for 42 (67) MS-WD systems. Our analysis more than doubles the number of MS-WD systems with precise distances known to date, and it boosts the number of such systems with precise age determination by an order of magnitude. With the advent of the Gaia DR2 (Gaia Collaboration, 2018, I/345) data, this approach will be applicable to a far larger sample, providing ages for many MS stars (that can yield detailed abundances for over 20 elements), especially in the age range of 2-8Gyr, where there are only few known star clusters.
2. Ages of field stars from white dwarf comp. in Gaia
ID:
ivo://CDS.VizieR/J/ApJS/253/58
Title:
Ages of field stars from white dwarf comp. in Gaia
Short Name:
J/ApJS/253/58
Date:
21 Oct 2021
Publisher:
CDS
Description:
We analyze 4050 wide binary star systems involving a white dwarf (WD) and usually a main-sequence (MS) star, drawn from the large sample assembled by Tian+ (2020, J/ApJS/246/4). Using the modeling code BASE-9, we determine the system's ages, the WD progenitors' zero-age MS masses, the extinction values (AV), and the distance moduli. Discarding the cases with poor age convergences, we obtain ages for 3551 WDs, with a median age precision of {sigma}{tau}/{tau}=20%, and system ages typically in the range of 1-6Gyr. We validated these ages against the very few known clusters and through cross validation of 236 WD-WD binaries. Under the assumption that the components are coeval in a binary system, this provides precise age constraints on the usually low-mass MS companions, mostly inaccessible by any other means.
3. AllWISE motion survey
ID:
ivo://CDS.VizieR/J/ApJ/783/122
Title:
AllWISE motion survey
Short Name:
J/ApJ/783/122
Date:
21 Oct 2021
Publisher:
CDS
Description:
The AllWISE processing pipeline has measured motions for all objects detected on Wide-field Infrared Survey Explorer (WISE) images taken between 2010 January and 2011 February. In this paper, we discuss new capabilities made to the software pipeline in order to make motion measurements possible, and we characterize the resulting data products for use by future researchers. Using a stringent set of selection criteria, we find 22445 objects that have significant AllWISE motions, of which 3525 have motions that can be independently confirmed from earlier Two Micron All Sky Survey (2MASS) images, yet lack any published motions in SIMBAD. Another 58 sources lack 2MASS counterparts and are presented as motion candidates only. Limited spectroscopic follow-up of this list has already revealed eight new L subdwarfs. These may provide the first hints of a "subdwarf gap" at mid-L types that would indicate the break between the stellar and substellar populations at low metallicities (i.e., old ages). Another object in the motion list --WISEA J154045.67-510139.3-- is a bright (J~9mag) object of type M6; both the spectrophotometric distance and a crude preliminary parallax place it ~6pc from the Sun. We also compare our list of motion objects to the recently published list of 762 WISE motion objects from Luhman (2014, J/ApJ/781/4). While these first large motion studies with WISE data have been very successful in revealing previously overlooked nearby dwarfs, both studies missed objects that the other found, demonstrating that many other nearby objects likely await discovery in the AllWISE data products.
4. APOGEE DR14:Binary companions of evolved stars
ID:
ivo://CDS.VizieR/J/AJ/156/18
Title:
APOGEE DR14:Binary companions of evolved stars
Short Name:
J/AJ/156/18
Date:
21 Oct 2021
Publisher:
CDS
Description:
Multi-epoch radial velocity measurements of stars can be used to identify stellar, substellar, and planetary-mass companions. Even a small number of observation epochs can be informative about companions, though there can be multiple qualitatively different orbital solutions that fit the data. We have custom-built a Monte Carlo sampler (The Joker) that delivers reliable (and often highly multimodal) posterior samplings for companion orbital parameters given sparse radial velocity data. Here we use The Joker to perform a search for companions to 96231 red giant stars observed in the APOGEE survey (DR14) with >=3 spectroscopic epochs. We select stars with probable companions by making a cut on our posterior belief about the amplitude of the variation in stellar radial velocity induced by the orbit. We provide (1) a catalog of 320 companions for which the stellar companion's properties can be confidently determined, (2) a catalog of 4898 stars that likely have companions, but would require more observations to uniquely determine the orbital properties, and (3) posterior samplings for the full orbital parameters for all stars in the parent sample. We show the characteristics of systems with confidently determined companion properties and highlight interesting systems with candidate compact object companions.
5. Astrometry & photometry of dwarf carbon stars
ID:
ivo://CDS.VizieR/J/AJ/155/252
Title:
Astrometry & photometry of dwarf carbon stars
Short Name:
J/AJ/155/252
Date:
21 Oct 2021
Publisher:
CDS
Description:
Parallaxes are presented for a sample of 20 nearby dwarf carbon stars. The inferred luminosities cover almost two orders of magnitude. Their absolute magnitudes and tangential velocities confirm prior expectations that some originate in the Galactic disk, although more than half of this sample are halo stars. Three stars are found to be astrometric binaries, and orbital elements are determined; their semimajor axes are 1-3 au, consistent with the size of an AGB mass-transfer donor star.
6. Bright white dwarfs for high-speed photometry
ID:
ivo://CDS.VizieR/J/MNRAS/472/4173
Title:
Bright white dwarfs for high-speed photometry
Short Name:
J/MNRAS/472/4173
Date:
21 Oct 2021
Publisher:
CDS
Description:
The upcoming NASA Transiting Exoplanet Survey Satellite (TESS) will obtain space-based uninterrupted light curves for a large sample of bright white dwarfs distributed across the entire sky, providing a very rich resource for asteroseismological studies and the search for transits from planetary debris. We have compiled an all-sky catalogue of ultraviolet, optical and infrared photometry as well as proper motions, which we propose as an essential tool for the preliminary identification and characterization of potential targets. We present data for 1864 known white dwarfs and 305 high-probability white dwarf candidates brighter than 17mag. We describe the spectroscopic follow-up of 135 stars, of which 82 are white dwarfs and 25 are hot subdwarfs. The new confirmed stars include six pulsating white dwarf candidates (ZZ Cetis), and nine white dwarf binaries with a cool main- sequence companion. We identify one star with a spectroscopic distance of only 25pc from the Sun. Around the time TESS is launched, we foresee that all white dwarfs in this sample will have trigonometric parallaxes measured by the ESA Gaia mission next year.
7. Companions to APOGEE stars. I.
ID:
ivo://CDS.VizieR/J/AJ/151/85
Title:
Companions to APOGEE stars. I.
Short Name:
J/AJ/151/85
Date:
21 Oct 2021
Publisher:
CDS
Description:
In its three years of operation, the Sloan Digital Sky Survey Apache Point Observatory Galactic Evolution Experiment (APOGEE-1) observed >14000 stars with enough epochs over a sufficient temporal baseline for the fitting of Keplerian orbits. We present the custom orbit-fitting pipeline used to create this catalog, which includes novel quality metrics that account for the phase and velocity coverage of a fitted Keplerian orbit. With a typical radial velocity precision of ~100-200 m/s, APOGEE can probe systems with small separation companions down to a few Jupiter masses. Here we present initial results from a catalog of 382 of the most compelling stellar and substellar companion candidates detected by APOGEE, which orbit a variety of host stars in diverse Galactic environments. Of these, 376 have no previously known small separation companion. The distribution of companion candidates in this catalog shows evidence for an extremely truncated brown dwarf (BD) desert with a paucity of BD companions only for systems with a<0.1-0.2 AU, with no indication of a desert at larger orbital separation. We propose a few potential explanations of this result, some which invoke this catalog's many small separation companion candidates found orbiting evolved stars. Furthermore, 16 BD and planet candidates have been identified around metal-poor ([Fe/H]<-0.5) stars in this catalog, which may challenge the core accretion model for companions >10 M_Jup_. Finally, we find all types of companions are ubiquitous throughout the Galactic disk with candidate planetary-mass and BD companions to distances of ~6 and ~16 kpc, respectively.
8. Four new eclipsing mid M-dwarf systems from MEarth
ID:
ivo://CDS.VizieR/J/AJ/156/140
Title:
Four new eclipsing mid M-dwarf systems from MEarth
Short Name:
J/AJ/156/140
Date:
21 Oct 2021
Publisher:
CDS
Description:
Using data from the MEarth-North and MEarth-South transit surveys, we present the detection of eclipses in four mid M-dwarf systems: LP 107-25, LP 261-75, LP 796-24, and LP 991-15. Combining the MEarth photometry with spectroscopic follow-up observations, we show that LP 107-25 and LP 796-24 are short-period (1.388 and 0.523 day, respectively) eclipsing binaries in triple-lined systems with substantial third-light contamination from distant companions. LP 261-75 is a short-period (1.882 day) single-lined system consisting of a mid M-dwarf eclipsed by a probable brown dwarf secondary, with another distant visual brown dwarf companion. LP 991-15 is a long-period (29.3 day) double-lined eclipsing binary on an eccentric orbit with a geometry that produces only primary eclipses. A spectroscopic orbit is given for LP 991-15, and initial orbits for LP 107-25 and LP 261-75.
9. Hawaii Infrared Parallax Program. I.
ID:
ivo://CDS.VizieR/J/ApJS/201/19
Title:
Hawaii Infrared Parallax Program. I.
Short Name:
J/ApJS/201/19
Date:
21 Oct 2021
Publisher:
CDS
Description:
Astrometry and photometry for 318 ultracool dwarfs in 265 systems that have measured trigonometric parallaxes. To be included in this tabulation, an object must have a spectral type >=M6 or a K-band absolute magnitude >8.5mag. Parallaxes, proper motions, and coordinates at a specified epoch are given for all objects. Photometric measurements in MKO, 2MASS, Spitzer, and WISE systems are given when available. Various other flags that provide additional information about the object or photometry are included.
10. Infrared photometry of binaries in Orion OB1
ID:
ivo://CDS.VizieR/J/AJ/160/268
Title:
Infrared photometry of binaries in Orion OB1
Short Name:
J/AJ/160/268
Date:
21 Oct 2021
Publisher:
CDS
Description:
Statistics of low-mass pre-main-sequence binaries in the Orion OB1 association with separations ranging from 0.6" to 20" (220 to 7400au at 370pc) are studied using images from the VISTA Orion mini survey and astrometry from Gaia. The input sample based on the CVSO catalog contains 1137 stars of K and M spectral types (masses between 0.3 and 0.9M{odot}), 1021 of which are considered to be association members. There are 135 physical binary companions to these stars with mass ratios above ~0.13. The average companion fraction is 0.09{+/-}0.01 over 1.2 decades in separation, slightly less than, but still consistent with, the field. We found a difference between the Ori OB1a and OB1b groups, the latter being richer in binaries by a factor of 1.6{+/-}0.3. No overall dependence of the wide- binary frequency on the observed underlying stellar density is found, although in the Ori OB1a off-cloud population, these binaries seem to avoid dense clusters. The multiplicity rates in Ori OB1 and in sparse regions like Taurus differ significantly, hinting that binaries in the field may originate from a mixture of diverse populations.

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