C. H. Chen and I. Kamp 2004 ApJ 602 985 doi:10.1086/381243
C. H. Chen1 and I. Kamp2
Show affiliationsWe have obtained Far Ultraviolet Spectroscopic Explorer and Hubble Space Telescope STIS spectra of HR 4796A, a nearby 8 Myr old main-sequence star that possesses a dusty circumstellar disk whose inclination has been constrained from high-resolution near-infrared observations to be ~17° from edge-on. We searched for circumstellar absorption in the ground states of C II λ1036.3, O I λ1039.2, Zn II λ2026.1, Lyman series H2, and CO (A-X) and failed to detect any of these species. We place upper limits on the column densities and infer upper limits on the gas masses assuming that the gas is in hydrostatic equilibrium, is well mixed, and has a temperature Tgas ~ 65 K. Our measurements suggest that this system possesses very little molecular gas. Therefore, we infer an upper limit for the gas-to-dust ratio (≤4.0) assuming that the gas is atomic. We measure less gas in this system than is required to form the envelope of Jupiter.
circumstellar matter; planetary systems: formation; stars: individual (HR 4796A)
Issue 2 (2004 February 20)
Received 2003 September 29, accepted for publication 2003 November 8
C. H. Chen and I. Kamp 2004 ApJ 602 985
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