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UV Spectroscopy of Star-Grazing Comets Within the 49 Ceti Debris DiskWe present the analysis of time-variable Doppler-shifted absorption features in far-UV spectra of the unusual 49 Ceti debris disk. This nearly edge-on disk is one of the brightest known and is one of the very few containing detectable amounts of circumstellar (CS) gas as well as dust. In our two visits of Hubble Space Telescope STIS spectra, variable absorption features are seen on the wings of lines arising from CII and CIV but not for any of the other CS absorption lines. Similar variable features have long been seen in spectra of the well-studied Beta Pictoris debris disk and attributed to the transits of star-grazing comets. We calculated the velocity ranges and apparent column densities of the 49 Cet variable gas, which appears to have been moving at velocities of tens to hundreds of kms(-1) relative to the central star. The velocities in the redshifted variable event seen in the second visit show that the maximum distances of the in falling gas at the time of transit were about 0.050.2 au from the central star. A preliminary attempt at a composition analysis of the redshifted event suggests that the C/O ratio in the in falling gas is super-solar, as it is in the bulk of the stable disk gas.
Document ID
20170003295
Document Type
Reprint (Version printed in journal)
Authors
Miles, Brittany E.
(California Univ. Los Angeles, CA, United States)
Roberge, Aki
(NASA Goddard Space Flight Center Greenbelt, MD United States)
Welsh, Barry
(Eureka Scientific, Inc. Oakland, CA, United States)
Date Acquired
April 7, 2017
Publication Date
June 21, 2016
Publication Information
Publication: The Astrophysical Journal
Volume: 824
Issue: 126
ISSN: 2041-8205
Subject Category
Astrophysics
Report/Patent Number
GSFC-E-DAA-TN41164
Funding Number(s)
CONTRACT_GRANT: GO-12901
CONTRACT_GRANT: NAS5-26555
Distribution Limits
Public
Copyright
Other
Keywords
far-UV spectra
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