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Observations of the bright novalike variable IX Velorum with the Hopkins Ultraviolet TelescopeThe Hopkins Ultraviolet Telescope, an experiment flown on the Space Shuttle as part of the Astro-1 mission, was used to obtain a spectrum of the novalike variable IX Vel (= CPD -48 deg 1577) in the wavelength range 830-1860 A. The observation revealed a rich absorption-line and continuum spectrum that peaks near 1050 A at a flux of 1.6 x 10(exp -11) ergs/sq cm/s/A. In the sub-Lyman-alpha region, some of the more prominent absorption lines are S VI lambda lambda-933, 945, C III lambda-977, Lyman-beta, O VI lambda lambda-1032, 1038, P V lambda lambda-1118, 1128, and C III lambda-1176. No emission was detected below the Lyman limit. The overall continuum shape of IX Vel in the FUV can be approximated using models of an optically thick accretion disk in which the integrated spectrum has been constructed by summing model stellar atmospheres or proper disk model spectra. However, if the distance to IX Vel is approximately 95 pc, standard disk models without reddening cannot simultaneously reproduce the color and flux in the UV. While interstellar reddening can reconcile this difference, the amount of reddening appears inconsistent with the absence of a 2200 A bump in the spectrum and the very low H I column density measured along the line of sight. Improved fits to the data can be obtained by modifying the accretion disk stucture within three white dwarf radii. None of the models reproduces the profiles of the Li- and Na-like ions, which are observed as strong but relatively narrow absorption lines, and which are almost surely due to a wind above the disk.
Document ID
19950034861
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Long, Knox S.
(Space Telescope Science Institute, Baltimore, MD United States)
Wade, Richard A.
(Pennsylvania State Univ. University Park, PA, United States)
Blair, William P.
(The Johns Hopkins Univ. Baltimore, MD, United States)
Davidsen, Arthur F.
(The Johns Hopkins Univ. Baltimore, MD, United States)
Hubeny, Ivan
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Date Acquired
August 16, 2013
Publication Date
May 10, 1994
Publication Information
Publication: Astrophysical Journal, Part 1
Volume: 426
Issue: 2
ISSN: 0004-637X
Subject Category
Astrophysics
Accession Number
95A66460
Funding Number(s)
CONTRACT_GRANT: NAGW-3171
CONTRACT_GRANT: NAS5-27000
Distribution Limits
Public
Copyright
Other

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