Bibcode
Scholz, R.-D.; McCaughrean, M. J.; Zinnecker, H.; Lodieu, N.
Bibliographical reference
Astronomy and Astrophysics, v.430, p.L49-L52 (2005)
Advertised on:
1
2005
Journal
Citations
64
Refereed citations
59
Description
We have used archival survey data, most importantly from the SuperCOSMOS
Sky Surveys, to derive accurate proper motions and thus confirm the
membership of two previously announced isolated brown dwarfs in the
nearby, ˜10 Myr old TW Hydrae Association (TWA), 2MASSW
J1207334-393254 and 2MASSW 1139511-315921 (Gizis cite{gizis02}), and to
discover a new substellar candidate. This new object, SSSPM J1102-3431,
has extremely red optical, optical-to-infrared, and near-infrared
colours (R-I=3.2, I-J=3.4, J-Ks=1.15), while low-resolution
not only classifies it as a late-type (M8.5) object, but also shows
spectral signatures of low gravity as expected for a young brown dwarf.
If it is a true TWA member, brown dwarf cooling models predict its mass
to be ˜ 20 MJup. SSSPM J1102-3431 lies only ˜12
arcmin away from the T Tauri star TW Hya and their proper motions agree
to within the errors, and thus it is possible that the two objects form
an extremely wide binary system, with a separation of ˜40 000 AU
at d=56 pc. We have also obtained improved proper motions for SSS
120727.4-324700 and SSS 101726.7-535428, recent additions to the list of
TWA members (Song et al. cite{song03}). The relatively large proper
motion of the latter object is consistent with the suggested proximity
(d˜22 pc) of this lowest-mass stellar representative of the TWA.
Based on archival data from the SuperCOSMOS Sky Surveys, 2MASS, and
DENIS, and on spectroscopic observations with the ESO 3.6-m telescope
(ESO 072.C-0630).