High and Low Stages of T CrB

Volume 19 number 1 (1990)

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T. Iijima

Astronomical Observatory of

Abstract

In the period from 1981 to 1987, probably except for some months in 1982, T CrB showed the usual spectrum of an M-type giant with prominent emission lines fo H I, He I, etc. The emission of HE II 4686 was temporarily observed. All emission lines weakened or disappeared in the early half of 1988. At the same time the luminosity slightly decreased (B=11.8). This stage continued until March 1990. Then in April the emissions of H I again became prominent and a weak emission of HE II 4686 was detected. The intensity of H I emissions has been largely varying in the period from April to July 1990, which might have been related to a pulsation of the cool component. It seems that the mass transfer in the binary system ceases in a certain unknown condition.