Investigating 2M1155−79B: A Nearby, Young, Low-mass Star Actively Accreting from a Nearly Edge-on, Dusty Disk

• Published in: The Astronomical journal Vol. 164; no. 5; pp. 227 - 235
• Main Authors: Dickson-Vandervelde, D. Annie, Kastner, Joel H., Gagné, Jonathan, Schneider, Adam C., Faherty, Jacqueline, Wilson, Emily C., Pinte, Christophe, Ménard, Francois
• Format: Journal Article
• Language: English
• Published: Madison The American Astronomical Society 01.11.2022; IOP Publishing; American Astronomical Society
• Subjects: Accretion disks; Age; Astronomy; Astrophysics; Deposition; Infrared analysis; Infrared astronomy; Infrared photometry; Infrared spectra; Low mass stars; M stars; Near infrared radiation; Planet formation; Pre-main sequence stars; Protoplanetary disks; Radiative transfer; Sciences of the Universe; Sky surveys (astronomy); Space telescopes; Spectral energy distribution; Star & galaxy formation; Star formation; Stars; Pre-main sequence stars; Protoplanetary disks; Astrophysics - Earth and Planetary Astrophysics; Astrophysics - Solar and Stellar Astrophysics
• ISSN: 0004-6256; 1538-3881
• DOI: 10.3847/1538-3881/ac9674

We investigate the nature of an unusually faint member of the ϵ Cha association ( D ∼ 100 pc, age ∼5 Myr), the nearest region of star formation of age <8 Myr. This object, 2MASS J11550336−7919147 (2M1155−79B), is a wide-separation (∼580 au), comoving companion to low-mass (M3) ϵ Cha association member 2MASS J11550485−7919108 (2M1155−79A). We present near-infrared (NIR) spectra of both components, along with analysis of photometry from Gaia Early Data Release 3, the Two Micron All Sky Survey, the Vista Hemisphere Survey, and the Wide-field Infrared Survey Explorer (WISE). The NIR spectrum of 2M1155−79B displays strong He i 1.083 emission, a sign of active accretion and/or accretion-driven winds from a circumstellar disk. Analysis of WISE archival data reveals that the mid-infrared excess previously associated with 2M1155−79A instead originates from the disk surrounding 2M1155−79B. Based on these results, as well as radiative transfer modeling of its optical/IR spectral energy distribution, we conclude that 2M1155−79B is most likely a young, late M star that is partially obscured by, and actively accreting from, a nearly edge-on circumstellar disk. This would place 2M1155−79B among the rare group of nearby ( D ≲ 100 pc), young (age <10 Myr) mid-M stars that are orbited by and accreting from highly inclined protoplanetary disks. Like these systems, the 2M1155−79B system is a particularly promising subject for studies of star and planet formation around low-mass stars.