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Hubble Space Telescope observations of cool white dwarf stars: Detection of new species of heavy elementsObservations of cool white dwarf stars with the Hubble Space Telescope (HST) has uncovered a number of spectral features from previouslly unobserved species. In this paper we present the data on four cool white dwarfs. We present identifications, equivalent width measurements, and brief summaries of the significance of our findings. The four stars observed are GD 40 (DBZ3, G 74-7 (DAZ), L 745-46A (DZ), and LDS 749B (DBA). Many additional species of heavey elements were detected in GD 40 and G 74-7. In L 745-46A, while the detections are limited to Fe 1, Fe II, and Mg II, the quality of the Mg II h and K line profiles should permit a test of the line broadening theories, which are so crucial to abundance determinations. The clear detection of Mg II h and k in LDS 749 B should, once an abundance determination is made, provide a clear test of the hypothesis that the DBA stars are the result of accretion from the interstellar medium. This star contains no other clear features other than a tantalizing hint of C II 1335 with a P Cygni profile, and some expected He 1 lines.
Document ID
Document Type
Reprint (Version printed in journal)
External Source(s)
Shipman, Harry
(University of Delaware, Newark, DE United States)
Barnhill, Maurice
(University of Delaware, Newark, DE United States)
Provencal, Judi
(University of Delaware, Newark, DE United States)
Roby, Scott
(University of Delaware, Newark, DE United States)
Bues, Irmela
(Remeis-Sternwarte Bamberg, Germany)
Cordova, France
(Pennsylvania State University University Park, PA, United States)
Hammond, Gordon
(University of South Florida, Tampa, FL United States)
Hintzen, Paul
(California State University Long Beach, CA, United States)
Koester, Detlev
(Universitat Kiel Kiel, Germany)
Liebert, James
(University of Arizona, Tucson, AZ United States)
Date Acquired
August 16, 2013
Publication Date
March 1, 1995
Publication Information
Publication: Astronomical Journal
Volume: 109
Issue: 3
ISSN: 0004-6256
Subject Category
Accession Number
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