TY - JOUR
T1 - Hubble space telescope observations of cool white dwarf stars
T2 - Detection of new species of heavy elements
AU - Shipman, Harry
AU - Barnhill, Maurice
AU - Provencal, Judi
AU - Roby, Scott
AU - Bues, Irmela
AU - Cordova, France
AU - Hammond, Gordon
AU - Hintzen, Paul
AU - Koester, Detlev
AU - Liebert, James
AU - Oswalt, Terry
AU - Starrfield, Sumner
AU - Wegner, Gary
AU - Weidemann, Volker
PY - 1995/3
Y1 - 1995/3
N2 - Observations of cool white dwarf stars with the Hubble Space Telescope has uncovered a number of spectral features from previously unobserved species. In this paper we present the data on four cool white dwarfs. We present line 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 749 B (DBA). Many additional species of heavy elements were detected in GD 40 and G 74-7. In L 745-46A,while the detections are limited to Fe I, 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 I lines.
AB - Observations of cool white dwarf stars with the Hubble Space Telescope has uncovered a number of spectral features from previously unobserved species. In this paper we present the data on four cool white dwarfs. We present line 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 749 B (DBA). Many additional species of heavy elements were detected in GD 40 and G 74-7. In L 745-46A,while the detections are limited to Fe I, 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 I lines.
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U2 - 10.1086/117356
DO - 10.1086/117356
M3 - Article
AN - SCOPUS:3943083283
SN - 0004-6256
VL - 109
SP - 1231
EP - 1238
JO - Astronomical Journal
JF - Astronomical Journal
IS - 3
ER -