AAS 205th Meeting, 9-13 January 2005
Session 11 Brown Dwarfs and Exoplanets
Poster, Monday, January 10, 2005, 9:20am-6:30pm, Exhibit Hall

Previous   |   Session 11   |   Next

[11.02] High-Temperature Gas in the Circumstellar Environment of the Young Brown Dwarf 2MASSW J1207334-393254

H. L. Shipman, J. E. Gizis (U. Del.)

This young brown dwarf, a likely member of the TW Hydrae association, has very strong and variable H-alpha emission (Gizis and Bhahrat, ApJL 608, L113, and references therein.) This feature is an indication of a chromosphere. The brown dwarf’s age, based on estimates of the cluster age and its low surface gravity, is approximately 10 Myr. We have obtained HST spectra at wavelengths of 1175 - 1700 A. Most of the features that are usually found in cool star chromospheres and transition regions are present in the spectrum. We have identified the lines of O I 1302-1306, C II 1335, He II 1640, C IV 1548+1550, and N V 1238. Conspicuous by its absence is the pair of Si IV resonance lines at 1394+1402. These lines are indicative of gas at a variety of temperatures, including relatively high ones, in the outer atmosphere of this brown dwarf. We will present the spectrum and a preliminary interpretation.

This research has been supported by NASA through the Hubble Space Telescope Guest Investigator program. H.L.S. acknowledges support from the National Science Foundation's Distinguished Teaching Scholars Program. DUE-0306557.

Previous   |   Session 11   |   Next

Bulletin of the American Astronomical Society, 36 5
© 2004. The American Astronomical Society.