Spectroscopic confirmation of the least massive known brown dwarf in chamaeleon

K. L. Luhman, Dawn E. Peterson, S. T. Megeath

Research output: Contribution to journalArticle

38 Citations (Scopus)

Abstract

We present spectroscopy of two candidate substellar members of the Chamaeleon I star-forming region. The candidates, which were identified photometrically by Oasa, Tamura, & Sugitani, have been observed at 1-2.5 μm during commissioning of the Gemini Near-Infrared Spectrograph. The late-type nature of one of the candidates, OTS 44, is confirmed through the detection of strong steam absorption bands. The other object, OTS 7, exhibits no late-type features and is likely a background star or galaxy. The gravity-sensitive shape of the H and K band continua demonstrate that OTS 44 is a young, pre-main-sequence object rather than a field dwarf. We measure a spectral type of M9.5 for OTS 44 based on a comparison of its spectrum to data for optically classified young late-type objects. Because OTS 44 is the coolest and faintest object with confirmed membership in Cha I, it is very likely the least massive known member of the cluster. By comparing the position of OTS 44 on the H-R diagram to the evolutionary models of Chabrier & Baraffe, we infer a mass of ∼0.015 M. Although this estimate is uncertain by at least a factor of 2, OTS 44 is nevertheless one of the least massive free-floating brown dwarfs confirmed spectroscopically to date.

Original languageEnglish (US)
Pages (from-to)565-568
Number of pages4
JournalAstrophysical Journal
Volume617
Issue number1 I
DOIs
StatePublished - Dec 10 2004

Fingerprint

OTS (ESA)
near infrared
diagram
spectroscopy
gravity
faint objects
stars
extremely high frequencies
young
steam
floating
spectrographs
diagrams
gravitation
galaxies
continuums
absorption spectra

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

Cite this

Luhman, K. L. ; Peterson, Dawn E. ; Megeath, S. T. / Spectroscopic confirmation of the least massive known brown dwarf in chamaeleon. In: Astrophysical Journal. 2004 ; Vol. 617, No. 1 I. pp. 565-568.
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Spectroscopic confirmation of the least massive known brown dwarf in chamaeleon. / Luhman, K. L.; Peterson, Dawn E.; Megeath, S. T.

In: Astrophysical Journal, Vol. 617, No. 1 I, 10.12.2004, p. 565-568.

Research output: Contribution to journalArticle

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AB - We present spectroscopy of two candidate substellar members of the Chamaeleon I star-forming region. The candidates, which were identified photometrically by Oasa, Tamura, & Sugitani, have been observed at 1-2.5 μm during commissioning of the Gemini Near-Infrared Spectrograph. The late-type nature of one of the candidates, OTS 44, is confirmed through the detection of strong steam absorption bands. The other object, OTS 7, exhibits no late-type features and is likely a background star or galaxy. The gravity-sensitive shape of the H and K band continua demonstrate that OTS 44 is a young, pre-main-sequence object rather than a field dwarf. We measure a spectral type of M9.5 for OTS 44 based on a comparison of its spectrum to data for optically classified young late-type objects. Because OTS 44 is the coolest and faintest object with confirmed membership in Cha I, it is very likely the least massive known member of the cluster. By comparing the position of OTS 44 on the H-R diagram to the evolutionary models of Chabrier & Baraffe, we infer a mass of ∼0.015 M⊙. Although this estimate is uncertain by at least a factor of 2, OTS 44 is nevertheless one of the least massive free-floating brown dwarfs confirmed spectroscopically to date.

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