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W. H. Bauer (Wellesley College), P. D. Bennett (Eureka Scientific), A. Brown (CASA, U. Colorado)
VV Cephei is an eclipsing binary system consisting of an M2 Iab supergiant star with a substantial circumstellar wind, and a hot companion, probably an early B-type main sequence star. We observed the system with the STIS spectrograph on the Hubble Space Telescope during total eclipse, when the hot star’s light was scattered by the extensive M supergiant wind. A rich emission-line spectrum was observed, with over two thousand emission features. A weak continuum is present during total eclipse, which strengthens markedly shortward of 1500 Å. Numerous circumstellar and interstellar absorption features are also present.
We have used an on-line compilation of spectral lines to identify these features (Hirata and Horaguchi 1995, Vizier On-line Data Catalog, VI/69). We grouped lines with similar upper-level excitation potentials and examined the spectra to see if lines from those levels were observed, and down to what value of oscillator strength the lines were seen. Well over 90% of the emission features have plausible identifications using this procedure. The majority of the lines arise from singly ionized elements in the iron group with upper levels up to 14 eV. There are many blends in the spectra; roughly 5500 lines were selected from the database. Only about 400 features appear to be unblended.
We present sample pages from an atlas in which we have annotated the emission lines and the circumstellar and interstellar absorption features with their identifications.
This work was based on observations made with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. These observations are associated with program GO-7269, and were supported by NASA through a grant from the Space Telescope Science Institute.
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Bulletin of the American Astronomical Society, 37 #4
© 2005. The American Astronomical Soceity.