2017/06/14 by Evgenya L. Shkolnik, Katelyn N. Allers, Adam L. Kraus +2 · 1 citation
Physics and Astronomy · #Astronomy and Astrophysical Research #Astrophysics and Star Formation Studies #Brown dwarf #Exoplanet #Infrared #Initial mass function #Radial velocity #Stars #Stellar classification #Stellar, planetary, and galactic studies #astro-ph.SR
paper · pdf · doi:10.3847/1538-3881/aa77fa
Accepted to AJ
arxiv created 2017/06/14 · openalex created_date 2017/06/23 · openalex publication_date 2017/07/24 · arxiv updated 2017/08/02 · openalex updated_date 2026/08/05
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 H α 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 22 ± 6 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.