High-resolution infrared spectroscopy of the brown dwarf epsilon Indi Ba

V V Smith, T Tsuji, K H Hinkle, K Cunha, R D Blum, J A Valenti, S T Ridgway, R R Joyce, P Bernath

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We report on the analysis of high-resolution infrared spectra of the newly discovered brown dwarf epsilon Ind Ba. This is the closest known brown dwarf to the solar system, with a distance of 3.626 pc. Spectra covering the ranges of lambdalambda2.308-2.317 mum and lambdalambda1.553-1.559 mum were observed at a resolution of lambda/Deltalambda = R = 50,000. The physical parameters of effective temperature and surface gravity are derived for e Ind Ba by comparison with model spectra calculated from atmospheres computed using unified cloudy models. The results are T-eff = 1500 +/- 100 K, log g = 5.2 +/- 0.3 (in units of cm s(-2)), placing it in the critical boundary between the late L and early T dwarfs. The high spectral resolution also allows us to measure an accurate projected rotational velocity, with v sin i = 28 +/- 3 km s(-1). Combined with a published luminosity for epsilon Ind Ba [with log (L/L.) = -4.71], the derived parameters result in a "spectroscopic" mass estimate of similar to30M(J), a radius of similar to0.062 R., and a maximum rotational period of similar to3.0 hr. A compilation and comparison of effective temperatures derived from spectroscopy using model atmospheres versus those derived from luminosities and theoretical M-bol-radius relations reveal a systematic disagreement in the Teff scale. The source of this disagreement is unknown.

Original languageEnglish
Pages (from-to)L107-L110
Number of pages4
JournalThe Astrophysical Journal
Issue number2
Publication statusPublished - 20 Dec 2003


  • infrared : stars
  • stars : fundamental parameters
  • stars : individual (epsilon Indi B)
  • stars : low-mass, brown dwarfs

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