Astronomy & Astrophysics

Free access article

Issue		A&A Volume 420, Number 2, June III 2004
Page(s)		647 - 653
Section		Stellar structure and evolution
DOI		10.1051/0004-6361:20035713

A&A 420, 647-653 (2004)
DOI: 10.1051/0004-6361:20035713

Infrared spectroscopy of a brown dwarf companion candidate near the young star GSC 08047-00232 in Horologium

R. Neuhäuser¹ and E. W. Guenther²

¹ Astrophysikalisches Institut, Universität Jena, Schillergäßchen 2-3, 07745 Jena, Germany
² Thüringer Landessternwarte Tautenburg, Sternwarte 5, 07778 Tautenburg, Germany

(Received 19 November 2003 / Accepted 3 March 2004)

Abstract
We present infrared H- and K-band spectra of a companion candidate $3^{\prime \prime}$ north of the young star GSC 08047-00232, a probable member of the nearby young Horologium association. From previously obtained JHK-band colors and the magnitude difference between primary and companion candidate, the latter could well be substellar (Neuhäuser et al. 2000) with the spectral type being roughly M 7-L 9 from the JHK colors (Chauvin et al. 2003). With the H- and K-band spectra now obtained with ISAAC at the VLT, the spectral type of the companion candidate is found to be M 6-9.5. Assuming the same age and distance as for the primary star ( ${\sim} 35$ Myr, 50 to 85 pc), this yields a mass of ${\sim} 25$ Jupiter masses for the companion, hence indeed substellar. After TWA-5 B and HR 7329 B, this is the third brown dwarf companion around a nearby ( $\le$ 100 pc) young ( $\le$ 100 Myr) star. A total of three confirmed brown dwarf companions (any mass, separation $\ge$ 50 AU) around 79 stars surveyed in three young nearby associations corresponds to a frequency of $6 \pm 4\%$ (with a correction for missing companions which are almost on the same line-of-sight as the primary star instead of being separated well), consistent with the expectation, if binaries have the same mass function as field stars. Hence, it seems that there is no brown dwarf desert at wide separations.

Key words: stars: late-type -- stars: low-mass, brown dwarfs -- stars: pre-main sequence

Offprint request: R. Neuhäuser, rne@astro.uni-jena.de

SIMBAD Objects

What is OpenURL?