COMMISSION 27 AND 42 OF THE IAU INFORMATION BULLETIN ON VARIABLE STARS Number 3804 Konkoly Observatory Budapest 12 November 1992 HU ISSN 0374 - 0676 THE H_Alpha PROFILE VARIATIONS IN THE SPECTRUM OF HD 225094, B3Ia The great deal of supergiants have variations of light, radial velocity, colour and occasionally in line profiles (see e.g. Abt, 1957; de Jager, 1980). The variations are explained probably by pulsations (Maeder, 1980; Lovy et al., 1984) and/or some other mechanisms. The star HD 225094 (HR 9097, BD +62d2356) is a member of the association Cas OB5 (Humphreys, 1978), has been classified as B3Ia supergiant and has the magnitude m_v=6.24 in the Bright Star Catalogue (Hoffleit, 1964). The light variability of this star was discovered by Guinan et al. (1982). They detected an irregular brightness variability with the full amplitude of about 0.1m on a timescale of several days. The observations by Hill et al. made in 1976 show the same results. Our recent (1991) observations in the Vilnius photometric system at Mt. Maidanak have resulted in a quite smooth change in the brightness with the full amplitude of about 0.1m and with possible characteristic timescale of 22-23 days. The supergiant HD 225094 has been observed with the 1.5-m telescope of Tartu Astrophysical Observatory at Toravere / Estonia during 1983-89. We have obtained ten spectra of satisfactory quality using the Cassegrain spectrograph ASP-32 on Kodak 103-aF plates. These spectra cover the H_Alpha region with the reciprocal dispersion 27 Angstrom * mm^-1 and are being used to investigate the possibility of H_alpha profile variations to test the hypothesis that the star has variability in spectral lines. All the spectrograms were digitized using the computer controlled Microdensitometer PDS 1010 of Tartu Astrophysical Observatory and elaborated using the spectrum-processing system KASPEK. Reduction routine steps are described by Annuk (1986). Despite the fact that the spectrograms have a quite high noise-level, the comparison of several spectra has shown that the profile of H_alpha line is Table 1. List of H_alpha profile observations for HD 225094 JD Date W(mAngstr.) V_rad 2445424.346 30. Mar. 83 - - 6509.292 19. Mar. 86 480(abs) 42.8(abs) 509.346 19. Mar. 86 307(abs) 23.3(abs) 707.604 04. Oct. 86 -390(em) -8.5(em) 871.336 16. Mar. 87 -582(em) -26.06(em) 909.519 23. Apr. 87 - - 7270.475 19. Apr. 88 - - 452.420 17. Oct. 88 -146(em) 6.7(em) 566.302 08. Feb. 89 - - 571.323 13. Feb. 89 - - [FIGURE 1] Fig. 1. Variability of H_alpha line profile in the spectrum of HD 225094 Despite the fact that the spectrograms have a quite high noise-level, the comparison of several spectra has shown that the profile of H_alpha line is variable on long timescale. The log of observations is presented in Table 1. The third and fourth columns give the values of equivalent width and radial velocity (when they were measurable) of H_alpha line, respectively. In Figure 1 the shapes of the profile are presented. One can see that the profile has mainly a "flooded" shape, but it is sometimes changing to either absorption or emission. The mechanism that might be responsible for the observed variations is the growth of the envelope with a following throw off of matter contained in it and/or "puffs" lacking spherical symmetry. Unfortunately our sequence of observations is irregular and we could not trace all the course of changing. Therefore more observations are needed to investigate this interesting supergiant. A. PASOK and I. KOLKA Tartu Astrophysical Observatory EE2444, Toravere ESTONIA References: Abt, H.A. 1957, Astrophys. J., 128, 138. [BIBCODE 1957ApJ...126..138A ] Annuk, K. 1986, Preprint, Acad. Sci. Estonia, A-5. de Jager, C. 1980, The Brightest Stars (D. Reidel. Publ. Co: Dordrecht, Holland) p. 340. [BIBCODE 1980GAM....19.....D ] Guinan, E.F., McCook, G.P., Weisenberger, A.G. 1982, IBVS, No. 2227. Hill, G., Hilditch, R, Pfannenschmidt, E. 1978, Publ. Dom. Astrophys. Obs., 15, 1. [BIBCODE 1976PDAO...15....1H ] Hoffleit, D., 1964, Catalogue of Bright Stars (Yale University Observatory: New Haven). [BIBCODE 1964cbs..book.....H ] Humphreys, R.M. 1978, Astrophys. J. Suppl., 88, 309. [BIBCODE 1978ApJS...38..309H ] Lovy, D., Maeder, A., Noels, A., Gabriel, M. 1984, Astron. Astrophys., 133, 307. [BIBCODE 1984A&A...133..307L ] Maeder, A., 1980, Astron. Astrophys., 90, 311. [BIBCODE 1980A&A....90..311M ]