MAGNETIC STARS. 6-th Scientific Conference of the Subcommission No.4 of the Multilateral Cooperation of the Academies of Sciences of Socialist Countries "Physics and Evolution of Stars". Riga, April 10-12, 1984, p. 69
Spectroscopic variability of the magnetic supergiant nu Cep
G. Scholz, E. Gerth
Academy of Sciences of the GDR, Central Institute of Astrophysics, Potsdam (GDR)
Zentralinstitut für Astrophysik der Akademie der Wissenschaften der DDR, DDR-1500 Potsdam Telegrafenberg
J.V. Glagolevskij, I.I. Romanyuk
Special Astrophysical Observatory, Academy of Sciences, USSRExtended abstract
Photometric and spectroscopic variability is a property of virtually all supergiants. Very different time scales of supergiant variability can be deduced from studies of individual stars, but these time scales are often ill-defined. In summer 1983 our spectroscopic observations yielded the recurrence of the strong magnetic field which was detected firstly in 1978. A search for period of the Beff value yields 5.27 years. The radial valocities give hints at the existence of very different periods. The longest period is 2.79 years, thus indicating a ratio of l:2 between both values. Other well-defined periods of the radial velocity variation can be near to 140 days (in the periodogram of the magnetic field strengths too), 40 days, 21.6 days, 14.8 days, 10.4 days and several smaller values which are not to be interpreted at present. Some periods are considerably greater than the period to be expected for the fundamental mode in case of radial pulsation (~10 days). This could be an indication for the existence of nonradial pulsations. As another interpretation, we should also consider the possibility that the variability is related to the rotation of the star. For the different hydrogen lines we observe an outflow of matter, therefore it is not to exclude that the variability is due to quasi-random surface motions, which produce the observed periods. Up to now, we have no reasonable explanation for the slow variation of the magnetic field and of the radial velocity with a time scale of years; maybe nu Cep is a binary.
(This is a summary of a lecture held by G. Scholz at the conference 1984 in Riga, which was printed as a manuscript in the conference booklet on page 69.)
The present article:P 63. Scholz, G., Gerth, E., Glagolevskij, Yu.V., Romanyuk, I.I.:
Spectroscopic variability of the magnetic supergiant nu Cep
MAGNETIC STARS. 6-th Scientific Conference of the Subcommission No. 4
of the Multilateral Cooperation of the Academies of Sciences of Socialist Countries
on Physics and Evolution of Stars, Riga 1984, p. 69
Abstract www.ewald-gerth.de/63abs.htm
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