2MASS J15460752−6258042: a mid-M dwarf hosting a prolonged accretion disc. Issue 1 (13th March 2020)

• Record Type: Journal Article
• Authors: Lee, Jinhee; Song, Inseok; Murphy, Simon
• Is Part Of: Monthly notices of the Royal Astronomical Society. Volume 494:Issue 1(2020)
• Page Start: 62
• Page End: 68
• Publication Date: 2020-03-13
• Subjects: accretion, accretion discs -- stars: late-type -- stars: pre-main-sequence -- open clusters and associations: individual; Astronomy -- Periodicals; Periodicals; 520.5
• DOI: 10.1093/mnras/staa689
• Languages: English
• ISSNs: 0035-8711

Abstract

ABSTRACT: We report the discovery of the oldest (∼55 Myr) mid-M type star known to host ongoing accretion. 2MASS J15460752–6258042 (2M1546, spectral type M5, 59.2 pc) shows spectroscopic signs of accretion such as strong H α, He i, and [O i ] emission lines, from which we estimate an accretion rate of ∼10 −10 M⊙ yr −1 . Considering the clearly detected infrared excess in all WISE bands, the shape of its spectral energy distribution (SED) and its age, we believe that the star is surrounded by a transitional disc, clearly with some gas still present at inner radii. The position and kinematics of the star from Gaia DR2 and our own radial-velocity measurements suggest membership in the nearby ∼55 Myr-old Argus moving group. At only 59 pc from Earth, 2M1546 is one of the nearest accreting mid-M dwarfs, making it an ideal target for studying the upper limit on the lifetimes of gas-rich discs around low-mass stars.