NICMOS Imaging of 2MASSWJ 1207334-393254 - A Planetary-Mass Companion Candidate
2MASSWJ 1207334-393254, a likely member of the nearby TW Hya association (age app 10 Myr and app 70 pc from Earth), is an app 30 Mjupiter brown dwarf (M8V spectrum due to its youth) for which a putative candidate planetary-mass companion was identified by Chauvin et al (Astron. and Astroph. 425, L29) with VLT/NACO observations in April 2004. Earlier, 2MASSWJ 1207334-393254 had been scheduled for observation in HST cycle 13 in a NICMOS H-band coronagraphic companion detection survey (GO 10176), but was re-programmed as an early "follow-up" observation given the ground-based derived implications for shorter wavelength space-based detection and efficacious diagnostic photometric measurements. Here, we present NICMOS camera 1 imaging photometry observations of 2MASSWJ 1207334-393254 and its point-like companion candidate in three bands: F090M (0.80 - 1.00 microns; similar to I-band), F110M (1.00 - 1.20 microns) and F160W (1.40 - 1.60 microns; similar to H-band) obtained on 28 Aug 2004. For the 773.7 +/- 2.2 mas (app 55 AU projected separation) distant companion we find in-band magnitudes for the companion candidate of F090M = 22.34 +/- 0.35 (delta-F090M = +7.14), F110M = 20.61 +/- 0.15 and (delta-F110M = +7.02) F160W = 18.24 +/- 0.02 (delta-F160W = +5.62). The NICMOS [0.90] - [1.6] micron color index of +4.1 +/- 0.4 is consistent with expectations for the spectral energy distribution of a mid to late L-dwarf (e.g., I - H of app +4.4 for spectral type L4). At the likely age of this candidate, the NICMOS and longer wavelength VLT/NACO derived photometric measures may implicate an object of several Jupiter masses. If the candidate companion is (as is yet to be) demonstrated to exhibit common proper motion with 2MASSWJ 1207334-393254 then the first image of a gravitationally bound companion of planetary mass may have already been secured. This work is supported through grants to the GO 10176 and 10177 teams from STScI, which is operated by AURA, Inc., under NASA contract NAS 5-26555.
American Astronomical Society Meeting Abstracts
- Pub Date:
- December 2004