Detection of circumstellar disks around nearby young brown dwarf candidates

TL;DR

This study identifies and characterizes circumstellar disks around young brown dwarf candidates, revealing new objects and accretion activity, which informs formation theories of low-mass objects and planet formation.

Contribution

It presents a new method combining photometry, Gaia parallaxes, and spectroscopy to detect disks and confirm youth in brown dwarf candidates, discovering 10 new disk-bearing objects.

Findings

Detected 23 brown dwarf candidates with disks, including 10 new objects.

Confirmed youth through lithium detection and accretion signatures.

Found a potential first brown dwarf member of a foreground population near Orion.

Abstract

It is important to detect and study circumstellar disks around late-M and brown dwarfs of nearby young associations to understand how these very low-mass objects form and how rocky planets form around them. The detection of new very low-mass members of nearby young associations will also significantly improve our current understanding of young associations. We searched for new young very low-mass members with circumstellar disks in a sample of 3928 candidates. We constructed spectral energy distributions of all candidates using observational photometric data from DENIS, 2MASS, and WISE and trigonometric parallaxes from Gaia to detect infrared excess emission that indicates the presence of circumstellar disks. We then followed up spectroscopic observations of candidates to search for lithium to confirm their youth. The H_alpha emission line was used to detect accretion. We detected 23 among the 3928 candidates with circumstellar disks: Ten objects are new, and 13 were previously reported in the literature. Our mass estimates also indicate that 21 are brown dwarf candidates and 2 are very low-mass stars. DENIS J0534552-104808 has a Gaia distance of 238 pc and might be the first brown dwarf candidate member of a foreground population in front of the Orion D cloud. This foreground population is probably associated with the supergiant kappa Ori. Based on our spectroscopic observations, we detected lithium in 11 candidates. We also identified seven accretors and one potential accretor. The intense long-lived accretion detected in DENIS-P J0500245-333042, a 20 Myr old brown dwarf candidate may be additional evidence to favor the formation of rocky planets around very low-mass objects.