The Active UV Phase of 59 Cyg

Abstract

Coordinated UV and visual observations of 59 Cyg in 1978–81 show strong mass ejection activity and strong variability in displacements and profiles of superionized lines during the new Be phase, starting from a “quasi normal B” phase in 1977, and increasing irregularly through 1981 to a low and then moderate Hα emission. These data show that visual data alone cannot describe the activity of the star.

Optical Emission-Line Spectra of Be Stars (Review Paper)

“…A recent addition to the list of very bright early-type stars occasionally showing characteristics of a Be star was provided by Singh (1982) who detected faint central Ha emission to be present in the spectrum of the B7V-type star Regulus (a Leo) in February, 1981. Finally, many faint new Be stars were detected during recent objectiveprism surveys both in the northern and in the southern Milky Way, as reported by Vega et al (1980), Vega (1982, by Mc Connell (1981) who covered a total of 4500 square degrees in the southern Milky Way finding altogether 731 new Ha emitting stellar objects, and by Pesch and Sanduleak ( , 1986 and Sanduleak and Pesch (1984) who discovered a total of 252 mostly new emission-line stars in the northern hemisphere. In a survey covering 59% of the northern sky above 10 galactic longitude, Stephenson (1986) recently found 206 faint Ha emission-line stars of which a few might prove to be Be stars.…”

“…Asymmetric double-peak emission lines are usually described by their V/R ratio, defined as the ratio of violet-side to red-side peak intensities above continuum in units of continuum intensity. For singly-peaked asymmetric emission lines, the corresponding designations may be "blue-dominated" if the short-wavelength part of the line is significantly more intense than the long-wavelength part, or "red-dominated" for the opposite case, following a recent suggestion by Mullan (1984). A useful measuring prescription how to determine V/R ratios as well as V and R peak intensities for singly-peaked asymmetric emission line profiles has also been devised by Doazan et al (1984).…”

“…In order to explain shell episodes in the framework of the rotating disk model for Be star envelopes, one has to assume that during shell episodes, the optical density in the disk for line radiation or the scale height of the disk or both increase for some time in such a way that the mean optical density of the line of sight to the star becomes sufficiently large in the line centre to produce shell absorption cores, as discussed by Hi rata and Kogure (1984).…”