Nearby Young, Active, Late-type Dwarfs in Gaia's First Data Release

Abstract

The Galex Nearby Young Star Survey (GALNYSS) has yielded a sample of ∼2000 UV-selected objects that are candidate nearby (D < ∼150 pc), young (age ∼10-100 Myr), late-type stars. Here, we evaluate the distances and ages of the subsample of (19) GALNYSS stars with Gaia Data Release 1 (DR1) parallax distances D ≤ 120 pc. The overall youth of these 19 mid-K to early-M stars is readily apparent from their positions relative to the loci of main sequence stars and giants in Gaia-based color-magnitude and color-color diagrams constructed for all stars detected by Galex and the Wide-field Infrared Space Explorer for which parallax measurements are included in DR1. The isochronal ages of all 19 stars lie in the range ∼10-100 Myr. Comparison with Li-based age estimates indicates a handful of these stars may be young main-sequence binaries rather than pre-main sequence stars. Nine of the 19 objects have not previously been considered as nearby, young stars, and all but one of these are found at declinations north of +30• . The Gaia DR1 results presented here indicate that the GALNYSS sample includes several hundred nearby, young stars, a substantial fraction of which have not been previously recognized as having ages < ∼100 Myr.

The Nearby, Young, χ1 Fornacis Cluster: Membership, Age, and an Extraordinary Ensemble of Dusty Debris Disks

“…Bolometric fluxes used to estimate log(L x /L bol ) were obtained from a star's G magnitude and spectral-typedependent bolometric correction (Pecaut & Mamajek 2013). The resulting NUV-G colors and log(L x /L bol ) values for the stars listed in Table 5 are within the ranges expected for stars of age <100 Myr (i.e., roughly -8 to -5 and -3.5 to -3.0, respectively; e.g., Kastner et al 2017). The lack of UV or X-ray counterparts to ∼2/3 of the stars in Tables 1 and 2 is readily explained as being due to the limited sensitivities of the ROSAT and GALEX all-sky surveys and the limited sky coverage of pointed XMM-Newton observations.…”

The CARMENES search for exoplanets around M dwarfs

“…However, both are young and candidate members of the AB Doradus association. The first was listed as a candidate by Schlieder et al (2012b), and the second by Kastner et al (2017). The second is also an active star discussed in Fuhrmeister et al (2018).…”

A kinematically unbiased, all-sky search for nearby, young, low-mass stars

“…This substitution is justified by the fact that, for our final sample of 146 objects, the absolute difference between DR1 and DR2 parallaxes is less than twice the combined error bar from DR1 and DR2 for > 95 per cent of the sample stars, and this difference is never larger than 5.0 pc. Expanding on Kastner et al (2017), our initial selection of stars for this study was based on cross-matching Gaia DR1 catalogue entries with the GALEX All-sky Imaging Survey (AIS) point source catalogue, but without the additional proper motion constraints used by Rodriguez et al (2013). 1 We adopted a cross-matching radius of 3 arcsec to associate Gaia DR1 entries with NUV photometry from the GALEX AIS and, subsequently, near-IR (JHK s ) and mid-IR (W1 − W4) photometry from 2MASS and WISE, respectively, using the Vizier cross-match service.…”

“…With the sudden availability of such data, in the form of the first two data releases from the Gaia space astrometry mission (Data Releases 1 and 2, hereafter DR1 and DR2; Gaia Collaboration 2016, 2018), the study of nearby, young stars and MGs can now make major strides. This potential motivated the recent study, described in Kastner et al (2017), in which we evaluated the distances and ages of all 19 nearby young star candidates from the sample of ∼2000 stars compiled by the GALEX (UV, Bianchi et al 2014) Nearby Young Star Survey (GALNYSS; Rodriguez et al 2013) that were included in Gaia DR1. The youth of the majority of these 19 mid-K to early-M stars was supported by their positions, relative to both the loci of main-sequence (MS) stars and theoretical isochrones, in Gaia colour-magnitude and colour-colour diagrams.…”

“…The youth of the majority of these 19 mid-K to early-M stars was supported by their positions, relative to both the loci of main-sequence (MS) stars and theoretical isochrones, in Gaia colour-magnitude and colour-colour diagrams. Surprisingly few of the GALNYSS stars included in Gaia DR1 have kinematics consistent with membership in known MGs, however (Kastner et al 2017). Recent all-sky searches for nearby, young stars are beginning to identify dozens of new young stars unassociated with nearby MGs (Bowler et al 2019;Schneider et al 2019).…”