Evolution of the symbiotic star AS 338 after its strong outburst in 1983

The photometric UBV observations of AS 338 that we began after its outburst in 1983 are presented. They were accompanied by yearly spectroscopic obser vations and by occasional estimations of the star's infrared JHKL magnitude s. In June 1993, the star's optical spectrum was extended to the ultraviole t via IUE observations of AS 338. Collectively, the above observations make it possible to trace the evolution of stellar activity over a period of 15 years in various spectral ranges. In particular, a short-time return of th e hot component of AS 338 to the state when He II lines reappeared in the s tar's spectrum was noted in 1993. At this time, a blend of the C IV lambda lambda 5802 and 5812 lines, which is typical of Wolf-Rayet spectra, was det ected in it. In June 1993, the temperature of the hot component was T-h app roximate to 8.8 x 10(4) K, and the ratio of its bolometric flux to that of the red giant was F-h,F-bol/F-g,F-bol approximate to 1.0. In August, its te mperature increased to similar to 1.0 x 10(5) K, while the bolometric Aux d ropped by a factor of similar to 1.5 (F-h,F-bol/F-g,F-bol approximate to 0. 7) In the B-V U diagram, the points referring to this so-called quiescent s tate form a separate group shifted in B-V from all the remaining ones locat ed in a horizontal strip with Delta U approximate to 3.(m)5 and Delta(B-V) approximate to 0.(m)4. This allows us to diagnose the state of the hot comp onent without spectroscopic observations of the star. In October 1993, the hot component flared up again. The main brightness rise took no more than 1 9 days. The outburst occurred shortly before eclipse egress of the hot comp onent, whose duration was similar to 0.01P(orb). In December 1993, F-h,F-bo l/F-g,F-bol less than or equal to 1.5 at maximum light. During the recurren t, even stronger outburst in April 1995, F-h,F-bol/F-g,F-bol less than or e qual to 3.4. The H alpha line during outbursts has a P Cyg profile and broa d wings stretching to velocities of +/-1500 km s(-1). The color temperature of the active hot component at short optical wavelengths and in the ultrav iolet lies in the range of effective temperatures for hot supergiants. Neve rtheless, it always produces an H II region in the circumstellar envelope t hat is larger in size than this binary system. (C) 2000 MAIK "Nauka/Interpe riodica".