ε Indi Ba,Bb: The nearest binary brown dwarf

M. J. McCaughrean, L. M. Close, R. D. Scholz, R. Lenzen, B. Biller, W. Brandner, M. Hartung, N. Lodieu

Research output: Contribution to journalArticle

133 Scopus citations

Abstract

We have carried out high angular resolution near-infrared imaging and low-resolution (R ∼ 1000) spectroscopy of the nearest known brown dwarf, ε Indi B, using the ESO VLT NAOS/CONICA adaptive optics system. We find it to be a close binary (as also noted by Volk et al. 2003), with an angular separation of 0.732 arcsec, corresponding to 2.65 AU at the 3.626 pc distance of the ε Indi system. In our discovery paper (Scholz et al. 2003), we concluded that ε Indi B was a ∼50 MJup 12.5 dwarf: our revised finding is that the two system components (ε Indi Ba and ε Indi Bb) have spectral types of T1 and T6, respectively, and estimated masses of 47 and 28 MJup, respectively, assuming an age of 1.3 Gyr, Errors in the masses are ±10 and ±7 MJup, respectively, dominated by the uncertainty in the age determination (0.8-2 Gyr range). This uniquely well-characterised T dwarf binary system should prove important in the study of low-mass, cool brown dwarfs. The two components are bright and relatively well-resolved: ε Indi B is the only T dwarf binary in which spectra have been obtained for both components. The system has a well-established distance and age. Finally, their orbital motion can be measured on a fairly short timescale (nominal orbital period ∼15 yrs), permitting an accurate determination of the true total system mass, helping to calibrate brown dwarf evolutionary models.

Original languageEnglish (US)
Pages (from-to)1029-1036
Number of pages8
JournalAstronomy and astrophysics
Volume413
Issue number3
DOIs
StatePublished - Jan 1 2004

Keywords

  • Astrometry
  • Stars: binaries: general
  • Stars: late-type
  • Stars: low mass, brown dwarfs
  • Surveys

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

Fingerprint Dive into the research topics of 'ε Indi Ba,Bb: The nearest binary brown dwarf'. Together they form a unique fingerprint.

  • Cite this

    McCaughrean, M. J., Close, L. M., Scholz, R. D., Lenzen, R., Biller, B., Brandner, W., Hartung, M., & Lodieu, N. (2004). ε Indi Ba,Bb: The nearest binary brown dwarf. Astronomy and astrophysics, 413(3), 1029-1036. https://doi.org/10.1051/0004-6361:20034292