Stars and brown dwarfs in the σ Orionis cluster (Research Note) III. OSIRIS/GTC low-resolution spectroscopy of variable sources
Data(s) |
01/10/2012
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Resumo |
Context. Although many studies have been performed so far, there are still dozens of low-mass stars and brown dwarfs in the young σ Orionis open cluster without detailed spectroscopic characterisation. Aims. We look for unknown strong accretors and disc hosts that were undetected in previous surveys. Methods. We collected low-resolution spectroscopy (R ~ 700) of ten low-mass stars and brown dwarfs in σ Orionis with OSIRIS at the Gran Telescopio Canarias under very poor weather conditions. These objects display variability in the optical, infrared, Hα, and/or X-rays on time scales of hours to years. We complemented our spectra with optical and near-/mid-infrared photometry. Results. For seven targets, we detected lithium in absorption, identified Hα, the calcium doublet, and forbidden lines in emission, and/or determined spectral types for the first time. We characterise in detail a faint, T Tauri-like brown dwarf with an 18 h-period variability in the optical and a large Hα equivalent width of –125 ± 15 Å, as well as two M1-type, X-ray-flaring, low-mass stars, one with a warm disc and forbidden emission lines, the other with a previously unknown cold disc with a large inner hole. Conclusions. New unrevealed strong accretors and disc hosts, even below the substellar limit, await discovery among the list of known σ Orionis stars and brown dwarfs that are variable in the optical and have no detailed spectroscopic characterisation yet. |
Formato |
application/pdf |
Identificador | |
Idioma(s) |
en |
Publicador |
EDP Sciencies |
Relação |
http://eprints.ucm.es/38133/ http://dx.doi.org/10.1051/0004-6361/201219626 10.1051/0004-6361/201219626 CSD2006-70 AyA2009-10368 AyA2011-30147-C03-03 |
Direitos |
info:eu-repo/semantics/openAccess |
Palavras-Chave | #Astrofísica #Astronomía |
Tipo |
info:eu-repo/semantics/article PeerReviewed |