Investigating 2M1155-7919B: a Nearby, Young, Low-Mass Star Actively Accreting from a Nearly Edge-on, Dusty Disk

Abstract

We investigate the nature of an unusually faint member of the $\epsilon$ Cha Association ($D\sim 100$ pc, age $\sim 5$ Myr), the nearest region of star formation of age $<$8 Myr. This object, 2MASS J11550336-7919147 (2M1155$-$79B), is a wide ($\sim$580 AU) separation, comoving companion to low-mass (M3) $\epsilon$ Cha Association member 2MASS J11550485-7919108 (2M1155$-$79A). We present near-infrared spectra of both components, along with analysis of photometry from Gaia EDR3, 2MASS, VHS, and WISE. The near-IR spectrum of 2M1155$-$79B displays strong He I 1.083 emission, a sign of active accretion and/or accretion-driven winds from a circumstellar disk. Analysis of WISE archival data reveals that the mid-infrared excess previously associated with 2M1155$-$79A instead originates from the disk surrounding 2M1155$-$79B. Based on these results, as well as radiative transfer modeling of its optical/IR spectral energy distribution, we conclude that 2M1155$-$79B is most likely a young, late-M, star that is partially obscured by, and actively accreting from, a nearly edge-on circumstellar disk. This would place 2M1155$-$79B among the rare group of nearby ($D\lesssim 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.

11 pages, 6 figures, accepted for publication in AJ

References in corpus (18)

• The Gaia mission
• Estimating distances from parallaxes. V: Geometric and photogeometric distances to 1.47 billion stars in Gaia Early Data Release 3
• New evolutionary models for pre-main sequence and main sequence low-mass stars down to the hydrogen-burning limit
• Monte Carlo radiative transfer in protoplanetary disks
• The unWISE Catalog: Two Billion Infrared Sources from Five Years of WISE Imaging
• Gaia-2MASS 3D maps of Galactic interstellar dust within 3 kpc
• An Analysis of the Shapes of Interstellar Extinction Curves. VII. Milky Way Spectrophotometric Optical-through-Ultraviolet Extinction and Its R-Dependence
• Probing T Tauri Accretion and Outflow with 1 Micron Spectroscopy
• Misaligned Protoplanetary Disks in a Young Binary System
• Modeling T Tauri Winds from He I 10830 Profiles
• Refining the Census of the Upper Scorpius Association with Gaia
• A Survey for New Members of the Taurus Star-Forming Region with the Sloan Digital Sky Survey
• New Extinction and Mass Estimates from Optical Photometry of the Very Low Mass Brown Dwarf Companion CT Chamaeleontis B with the Magellan AO System
• Gaia-based Isochronal, Kinematic, and Spatial Analysis of the $\epsilon$ Cha Association
• Star-disk interaction in the T Tauri star V2129 Oph: An evolving accretion-ejection structure
• Exploring the planetary-mass population in the Upper Scorpius association
• A faint companion around CrA-9: protoplanet or obscured binary?
• Sporadic and intense accretion in a 1 Myr-old brown dwarf candidate