Volatile-Rich Circumstellar Gas in the Unusual 49 Ceti Debris Disk

Abstract

We present Hubble Space Telescope STIS far-UV spectra of the edge-on disk around 49 Ceti, one of the very few debris disks showing sub-mm CO emission. Many atomic absorption lines are present in the spectra, most of which arise from circumstellar gas lying along the line-of-sight to the central star. We determined the line-of-sight CI column density, estimated the total carbon column density, and set limits on the OI column density. Surprisingly, no line-of-sight CO absorption was seen. We discuss possible explanations for this non-detection, and present preliminary estimates of the carbon abundances in the line-of-sight gas. The C/Fe ratio is much greater than the solar value, suggesting that 49 Cet harbors a volatile-rich gas disk similar to that of Beta Pictoris.

Accepted for publication in ApJ Letters. 5 pages, 4 figures

References in corpus (5)

• The Structure of the Local Interstellar Medium V: Electron Densities
• Molecular Gas Clumps from the Destruction of Icy Bodies in the $\beta$ Pictoris Debris Disk
• The Carbon-Rich Gas in the Beta Pictoris Circumstellar Disk
• A Resolved Molecular Gas Disk around the Nearby A Star 49 Ceti
• The Structure of the Local Interstellar Medium. VI. New MgII, FeII, and MnII Observations Toward Stars Within 100 Parsecs

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