Search

The results of studies of superfast line profile variability in spectra of early-type star on minute and second time scales are reviewed. The spectra of bright OBA stars were obtained with the 6-meter BTA telescope of the Special Astrophysical Observatory (SAO, Russia). Additionally selected OBA stars were observed with the 1-m telescope of SAO and with the 1.25-m telescope of the Crimean Astronomical Station of SAI, Russia. The variations of the line profiles are analyzed. Regular line profiles variations (LPVs) of the H, HeI, FeII, NII, OII, and SiII in spectra of program stars with periods from 10 to ~120 minutes and amplitudes of 1–2% of the continuum level were detected. The short-time transient quasi-regular LPVs with periods from 1 to 10 minutes and lifetime in the interval 20–100 minutes were also registered. The periods of such transients appeared to be variable. Their frequencies can change up to 20% during their lifetime. A nature of such transients is unknown and a similarity of their generation to that for the five-minute solar oscillations is an open question. A connection between irregular LPVs and local magnetic fields generating the stellar micro-flares is proposed. [ABSTRACT FROM AUTHOR]

We have carried out photometry and spectroscopy of the star V1327 Aql ( R = 16 m ) as part of our program of observations of poorly studied cataclysmic variables using the 1.5-m optical Russian—Turkish telescope (RTT-150, Turkey) and the 6-m telescope of the Special Astrophysical Observatory of the Russian Academy of Sciences. After analyzing our photometry, we have re-classified the variable as an RR Lyrae star. Our BV R photometry during 10 nights reveals brightness variations with the period 12h49m, with the B, V, and R amplitudes being 1.36 m , 1.13 m , and 1.11 m , respectively. We derived the first estimates of the star’s atmospheric parameters from our moderate-resolution spectra: T eff = 6280 K, log g = 3.3, [M/H] = −1.05. The extremely high radial velocity of the star’s motion ( V R = −470 km/s) and the star’s large distances to the Galactic center (13.1 kpc) and disk (4.2 kpc) testify to a probable extragalactic origin of this object. [ABSTRACT FROM AUTHOR]