Abstract
We confirm 66 low-mass stellar and brown dwarf systems (K7-M9) plus 19 visual or spectroscopic companions of the β Pictoris moving group (BPMG). Of these, 41 are new discoveries, increasing the known low-mass members by 45%. We also add four objects to the 14 known with masses predicted to be less than . Our efficient photometric + kinematic selection process identified 104 low-mass candidates, which we observed with ground-based spectroscopy. We collected infrared observations of the latest spectral types (>M5) to search for low-gravity objects. These and all <M5 candidates were observed with high-resolution optical spectrographs to measure the radial velocities and youth indicators, such as lithium absorption and Hα emission, needed to confirm BPMG membership, achieving a 63% confirmation rate. We also compiled the most complete census of BPMG membership, with which we tested the efficiency and false-membership assignments using our selection and confirmation criteria. Using the new census, we assess a group age of 226 Myr, consistent with past estimates. With the now-densely sampled lithium depletion boundary, we resolve the broadening of the boundary by either an age spread or astrophysical influences on lithium-burning rates. We find that 69% of the now-known members with AFGKM primaries are M stars, nearing the expected value of 75%. However, the new initial mass function for the BPMG shows a deficit of 0.2-0.3 stars by a factor of ∼2. We expect that the AFGK census of the BPMG is also incomplete, probably due to biases of searches toward the nearest stars.
Original language | English (US) |
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Article number | 69 |
Journal | Astronomical Journal |
Volume | 154 |
Issue number | 2 |
DOIs | |
State | Published - Aug 2017 |
Keywords
- activity stars
- binaries
- individual: (β Pictoris Moving Group) stars
- kinematics and dynamics stars
- low-mass stars
- pre-main sequence
- spectroscopic open clusters and associations
ASJC Scopus subject areas
- Astronomy and Astrophysics
- Space and Planetary Science
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ACRONYM II. The {beta} Pictoris Moving Group
Shkolnik, E. (Creator), Allers, K. N. (Creator), Kraus, A. L. (Creator), Liu, M. C. (Creator) & Flagg, L. (Creator), Strasbourg Astronomical Data Center, 2018
DOI: 10.26093/cds/vizier.51540069, https://cdsarc.cds.unistra.fr/viz-bin/cat/J/AJ/154/69
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