HST synthetic spectral analysis of U Gem in early and late quiescence: A heated white dwarf and accretion belt?

F. H. Cheng, E. M. Sion, Keith Horne, I. Hubeny, M. Huang, S. D. Vrtilek

Research output: Contribution to journalArticle

17 Scopus citations

Abstract

We have re-examined two archival HST FOS G130H spectra of the prototype dwarf nova U Geminorum obtained during its quiescence 13 days and 70 days after a wide outburst. Using synthetic spectral fitting with two flux-emitting components, a slowly rotating white dwarf photosphere, and a rapidly spinning accretion belt (Vrot sin i=3200 km s-1) significantly improves the spectral fit but does not provide a unique solution. We found clear evidence for the cooling of the white dwarf, confirming earlier results, and evidence for the cooling of the accretion belt or gas in Keplerian motion as well. If an accretion belt is really present, then for the white dwarf and belt, respectively, 13 days post-outburst, we find Twd=37 000 ±400 K and Tbelt=45 000±2500 K, while at 70 days post outburst, we find Twd=33 500±700 K and Tbelt=37 500±4000 K. These results are compared with our HST GHRS G160M observations obtained 13 days and 61 days after a narrow outburst of U Gem.

Original languageEnglish (US)
Pages (from-to)1165-1169
Number of pages5
JournalAstronomical Journal
Volume114
Issue number3
DOIs
StatePublished - Jan 1 1997

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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