Detection of circumstellar disks around nearby young brown dwarf candidates

¹ Department of Physics, International University, Ho Chi Minh City, Vietnam
² Vietnam National University, Ho Chi Minh City, Vietnam
³ Research School of Astronomy and Astrophysics, Australian National University, Cotter Rd, Weston, ACT 2611, Australia
⁴ Instituto de Astrofísica de Canarias, Spain

^★ Corresponding author: pbngoc@hcmiu.edu.vn

Received: 6 September 2024
Accepted: 12 July 2025

Abstract

Context. 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.

Aims. We searched for new young very low-mass members with circumstellar disks in a sample of 3928 candidates.

Methods. 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 Hα emission line was used to detect accretion.

Results. 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 κ 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.