Revisiting the membership, multiplicity, and age of the Beta Pictoris Moving Group in the Gaia era

Author(s): Rena A. Lee, Eric Gaidos, Jennifer van Saders, Gregory A. Feiden, Jonathan Gagné
Abstract: Determining the precise ages of young (tens to a few hundred Myr) kinematic (‘moving’) groups is important for placing star, protoplanetary disc, and planet observations on an evolutionary timeline. The nearby ∼25 Myr-old β Pictoris Moving Group (BPMG) is an important benchmark for studying stars and planetary systems at the end of the primordial disc phase. Gaia DR3 astrometry and photometry, combined with ground-based observations and more sophisticated stellar models, permit a systematic re-evaluation of BPMG membership and age. We combined Gaia astrometry with previously published radial velocities to evaluate moving group membership in a Bayesian framework. To minimize the effect of unresolved stellar multiplicity on age estimates, we identified and excluded multistar systems using Gaia astrometry, ground-based adaptive optics imaging, and multi-epoch radial velocities, as well as literature identifications. We estimated age using isochrone and lithium-depletion-boundary fitting with models that account for the effect of magnetic activity and spots on young, rapidly rotating stars. We find that age estimates are highly model-dependent; Dartmouth magnetic models with ages of 23 ± 8 and 33⁺₋₁₁⁹ Myr provide best fits to the lithium depletion boundary and Gaia M_G versus B_P–R_P colour–magnitude diagram, respectively, whereas a Dartmouth standard model with an age of 11⁺₋₃⁴ Myr provides a best fit to the 2-Micron All-Sky Survey-Gaia M_KS versus B_P–R_P colour–magnitude diagram.
Organisation(s): Department of Astrophysics
External organisation(s): University of Hawaii at Manoa, University of Hawaii, Eidgenössische Technische Hochschule Zürich, University of North Georgia, Planétarium Rio Tinto Alcan, University of Montreal
Journal: Monthly Notices of the Royal Astronomical Society
Volume: 528
Pages: 4760-4774
No. of pages: 15
ISSN: 0035-8711
DOI: https://doi.org/10.1093/mnras/stae007
Publication date: 03-2024
Peer reviewed: Yes
Austrian Fields of Science 2012: 103003 Astronomy, 103004 Astrophysics
Keywords
ASJC Scopus subject areas: Astronomy and Astrophysics, Space and Planetary Science
Portal url: https://ucrisportal.univie.ac.at/en/publications/e7440c21-ac95-4660-b6d2-fffb0e29bbce

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