Refining the Census of the Upper Scorpius Association with Gaia

Journal Article · Wed Jul 01 04:00:00 EDT 2020 · The Astronomical Journal (Online)

DOI:https://doi.org/10.3847/1538-3881/AB9599· OSTI ID:23013276

Luhman, K. L. ^[1]

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1. Department of Astronomy and Astrophysics, The Pennsylvania State University, University Park, PA 16802 (United States)

We have refined the census of stars and brown dwarfs in the Upper Sco association (∼10 Myr, ∼145 pc) by (1) updating the selection of candidate members from our previous survey to include the high-precision astrometry from the second data release of Gaia, (2) obtaining spectra of a few hundred candidate members to measure their spectral types and verify their youth, and (3) assessing the membership (largely with Gaia astrometry) of 2020 stars toward Upper Sco that show evidence of youth in this work and previous studies. We arrive at a catalog of 1761 objects that are adopted as members of Upper Sco. The distribution of spectral types among the adopted members is similar to those in other nearby star-forming regions, indicating a similar initial mass function. In previous studies, we have compiled mid-infrared photometry from the Wide-field Infrared Survey Explorer and the Spitzer Space Telescope for members of Upper Sco and used those data to identify the stars that show evidence of circumstellar disks; we present the same analysis for our new catalog of members. As in earlier work, we find that the fraction of members with disks increases with lower stellar masses, ranging from ≲10% for >1 M {sub ⊙} to ∼22% for 0.01–0.3 M {sub ⊙}. Finally, we have estimated the relative ages of Upper Sco and other young associations using their sequences of low-mass stars in M{sub G{sub R{sub P}}} versus G {sub BP} − G {sub RP}. This comparison indicates that Upper Sco is a factor of two younger than the β Pic association (21–24 Myr) according to both nonmagnetic and magnetic evolutionary models.

• OSTI ID: 23013276
• Journal Information: The Astronomical Journal (Online), Journal Name: The Astronomical Journal (Online) Journal Issue: 1 Vol. 160; ISSN 1538-3881
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
COMPARATIVE EVALUATIONS
DISTRIBUTION
DWARF STARS
INFRARED SURVEYS
MASS
PHOTOMETRY
REFINING
SPACE
SPECTRA
TELESCOPES