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Two-phase ultraviolet spectrophotometry of the pulsating white dwarf ZZ PisciumSpectra of the pulsating white dwarf ZZ Psc (= G29-38) were obtained using the International Ultraviolet Explorer. By using a multiple-exposure technique in conjunction with simultaneous ground-based exposure-metering photometry, it was possible to obtain mean on-pulse and off-pulse spectra in the 1950-1310 A wavelength range. The ratio of the time-averaged on-pulse to off-pulse spectra is best fitted by a temperature variation that is in phase with the optical light variation. This result is consistent with the hypothesis that the observed variation is due to a high-order nonradial pulsation. Conventional ultraviolet spectra of ZZ Psc showed broad absorption features at 1390 and 1600 A. These features are also found in the spectra of the cool DA-type white dwarfs G226-29 and G67-23, and appear to increase in strength with decreasing temperature. A possible explanation for the 1600 A feature is absorption by the satellite band of resonance-broadened hydrogen Ly-alpha. Such absorption would also help explain a discrepancy between the observed pulsation amplitude shortward of 1650 A and the predicted amplitudes based on model atmospheres.
Document ID
19850044862
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Bond, H. E.
(Louisiana State Univ. Baton Rouge, LA, United States)
Kemper, E.
(Louisiana State University Baton Rouge, LA, United States)
Grauer, A. D.
(Arkansas, University Little Rock, AR, United States)
Holm, A. V.
(Louisiana State Univ. Baton Rouge, LA, United States)
Panek, R. J.
(Louisiana State Univ. Baton Rouge, LA, United States)
Schiffer, F. H., III
(Louisiana State Univ. Baton Rouge, LA, United States)
Date Acquired
August 12, 2013
Publication Date
February 15, 1985
Publication Information
Publication: Astrophysical Journal, Part 1
Volume: 289
ISSN: 0004-637X
Subject Category
Astrophysics
Accession Number
85A27013
Funding Number(s)
CONTRACT_GRANT: NAS5-25774
Distribution Limits
Public
Copyright
Other

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