BE Ursae Majoris: A Detached Binary with a Unique Reprocessing Spectrum

May 1987 • 1987ApJ...316..399F

Authors • Ferguson, Donald H. • Liebert, James • Cutri, Roc • Green, Richard F. • Willner, S. P. • Steiner, Joao E. • Tokarz, Susan

Abstract • New infrared photometry, optical and UV spectrophotometry, and a photographic ephemeris are presented for the detached binary BE UMa. Results show the primary to be a DO white dwarf with an effective temperature of 80,000 + or - 15,000 K and a mass of 0.6 + or - 0.1 solar masses. No evidence is found for variability of the primary. The main-sequence secondary star is shown to be of early-M spectral type, with a formal range of M1-M5 being possible. A reflection effect in reprocessed line and continum radiation is produced by EUV radiation from the primary incident on the secondary atmosphere. It is suggested that the temperature of the reprocessed component of the secondary's atmosphere is in the 5000-8500 K range, and that emission lines of decreasing ionization form deeper in the irradiated envelope. Relatively narrow He II and high-excitation metal lines are formed from recombination and continuum fluorescence processes.

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Roc Cutri

IPAC Deputy Director