Astrometric and Spectroscopic Confirmation of a Brown Dwarf Companion to   GSC 08047-00232
  We report VLT/NACO imaging observations of the stars GSC 08047-00232 and HIP 6856, probable members of the large Tucana-Horologium association. During our previous ADONIS/SHARPII deep imaging survey, a substellar candidate companion was discovered around each star. Based on VLT/NACO astrometric measurements, we find that GSC 08047-00232 and the faint candidate companion near to it share the same proper motion with a significance of 3.1sigma. On the contrary, the candidate companion to HIP 6856 is probably a background object with a significance of 4.3sigma. We also detect a new fainter and closer candidate companion to HIP 6856, but which is likely a background object too with a significance of 4sigma. Recent VLT/NACO spectroscopic measurements of GSC 08047-00232 finally confirm the substellar nature of this young brown dwarf with a derived spectral type M9.5. GSC 08047-00232 B, with an estimated mass of 25MJup and an effective temperature of 2100K, is presently the third substellar companion identified among young, nearby associations. 
G. Chauvin, A.-M. Lagrange, F. Lacombe, C. Dumas, D. Mouillet, B.   Zuckerman, E. Gendron, I. Song, J.-L. Beuzit, P. Lowranc...