2023/09/29 by Sarah Betti, Katherine B. Follette, Betti, S. K. +25 · 6 citations
Environmental Science · Physics and Astronomy · #Astro and Planetary Science #Astrophysics of Galaxies (astro-ph.GA) #Earth and Planetary Astrophysics (astro-ph.EP) #FOS: Physical sciences #Isotope Analysis in Ecology #Solar and Stellar Astrophysics (astro-ph.SR) #Stellar, planetary, and galactic studies
paper · pdf · doi:10.48550/arxiv.2310.00072
openalex publication_date 2023/09/29 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/01
Accretion rates (M) of young stars show a strong correlation with object mass (M); however, extension of the M-M relation into the substellar regime is less certain. Here, we present the Comprehensive Archive of Substellar and Planetary Accretion Rates (CASPAR), the largest to-date compilation of substellar accretion diagnostics. CASPAR includes: 658 stars, 130 brown dwarfs, and 10 bound planetary mass companions. In this work, we investigate the contribution of methodological systematics to scatter in the M-M relation, and compare brown dwarfs to stars. In our analysis, we rederive all quantities using self-consistent models, distances, and empirical line flux to accretion luminosity scaling relations to reduce methodological systematics. This treatment decreases the original 1σ scatter in the log M-log M relation by ∼17%, suggesting that it makes only a small contribution to the dispersion. CASPAR rederived values are best fit by M∝ M2.02±0.06 from 10~MJ to 2~M_\odot, confirming previous results. However, we argue that the brown dwarf and stellar populations are better described separately and by accounting for both mass and age. Therefore, we derive separate age-dependent M-M relations for these regions, and find a steepening in the brown dwarf M-M slope with age. Within this mass regime, the scatter decreases from 1.36 dex to 0.94 dex, a change of ∼44%. This result highlights the significant role that evolution plays in the overall spread of accretion rates, and suggests that brown dwarfs evolve faster than stars, potentially as a result of different accretion mechanisms.