Title

S Ori J053825.4-024241: A Classical T Tauri-Like Object At The Substellar Boundary

Keywords

Accretion, accretion discs; Galaxy: open clusters and associations: individuals: σ Orionis; Stars: low mass, brown dwarfs; Stars: variables: general

Abstract

We present a spectrophotometric analysis of SOri J053825.4-024241, a candidate member close to the substellar boundary of the young (1-8Myr), nearby (∼360pc) σ Orionis star cluster. Our optical and near-infrared photometry and low-resolution spectroscopy indicate that S Ori J053825.4-024241 is a likely cluster member with a mass estimated from evolutionary models at 0.06 -0.02+0.07 M ⊙, which makes the object a probable brown dwarf. The radial velocity of S Ori J053825.4-024241 is similar to the cluster systemic velocity. This target, which we have classified as an M 6.0 ±1.0 low-gravity object, shows excess emission in the near-infrared and anomalously strong photometric variability for its type (from the blue to the J band), suggesting the presence of a surrounding disc. The optical spectroscopic observations show a continuum excess at short wavelengths and a persistent and resolved H α emission (pseudo-equivalent width of ∼-250 Å) in addition to the presence of other forbidden and permitted emission lines, which we interpret as indicating accretion from the disc and possibly mass loss. We conclude that despite the low mass of S Ori J053825.4-024241, this object exhibits some of the properties typical of active classical T Tauri stars. © ESO 2005.

Publication Date

1-1-2006

Publication Title

Astronomy and Astrophysics

Volume

445

Issue

1

Number of Pages

143-153

Document Type

Article

Personal Identifier

scopus

DOI Link

https://doi.org/10.1051/0004-6361:20053466

Socpus ID

29444444277 (Scopus)

Source API URL

https://api.elsevier.com/content/abstract/scopus_id/29444444277

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