ULTRAVIOLET SPECTROSCOPIC ANALYSIS OF TRANSIENT MASS FLOW OUTBURST IN U CEPHEI

作者：Tupa Peter R^*; DeLeo Gary G; McCluskey George E; Kondo Yoji; Sahade Jorge; Gimenez Alvaro; Caton Daniel B

来源：Astrophysical Journal, 2013, 775(1): 46.

DOI：10.1088/0004-637X/775/1/46

• binaries: eclipsing
• binaries: spectroscopic
• circumstellar matter
• ultraviolet: stars

Spectra from the International Ultraviolet Explorer taken in 1989 September over one full orbital period of U Cephei (U Cep, HD 5796) are analyzed. The TLUSTY and SYNSPEC stellar atmospheric simulation programs are used to generate synthetic spectra to which U Cep continuum levels are normalized. Absorption lines attributed to the photosphere are divided out to isolate mass flow and accretion spectra. A radial velocity curve is constructed for conspicuous gas stream features, and shows evidence for a transient flow during secondary eclipse with outward velocities ranging between 200 and 350 km s(-1), and a number density of (3 +/- 2) x 10(10) cm(-3). The validity of C IV 1548 and 1550 and Si IV 1393 and 1402 lines are re-examined in the context of extreme rotational blending effects. A G-star to B-star mass transfer rate of (5 +/- 4) x 10(-9) M-circle dot yr(-1) is calculated as an approximate upper limit, and a model system is presented.

• 出版日期2013-9-20