COMMISSION 27 OF THE I. A. U. INFORMATION BULLETIN ON VARIABLE STARS Number 2082 Konkoly Observatory Budapest 1982 February 4 HU ISSN 0374-0676 o And: A NEW ACTIVE EPISODE? After the shell episode of July 1975 (I.A.U. Circ. No. 2802) we have performed continuous photoelectric observations of the shell star o And, beginning in the October of the same year (Bossi et al., 1976, Guerrero and Mantegazza, 1978, Bossi et al., 1980). In Table I abc we report the results of new photoelectric observations taken in 1980 and 1981. The Delta m_B values (the comparison star is 2 And) are also represented in Figure 1 compared with all those obtained since 1978. In the same figure the bars indicate, in magnitude, the range covered during the period of the observations, no bar refers to the nights in which the observations were of short duration. In addition to the lasting short period light variations, we immediately remark a considerable light decrease after the maximum reached in 1979, moreover the behaviour of the light curve suggests a future similar trend. Such a behaviour which can indicate an activity (Bossi et al., 1980), induced us to get some blue and red grating spectra of this star (with a dispersion of 35 and 18 A/mm). Figure 2, in which the transparency of the photographic emulsion is plotted, shows the H_alpha profile obtained from a red spectrum of November 28, 1981, in which a strong absorption core is flanked by two weak emission components. Moreover, in the blue spectra we observed a remarkable shell absorption superimposed on the other hydrogen photospheric lines. Table I a Photoelectric V observations -------------------------------------------------------- Hel. J.D. Hel. J.D. 2400000+ DeltaV Sigma 2400000+ DeltaV Sigma -------------------------------------------------------- 44473.424 1.503 .005 44540.267 1.444 .002 44484.341 1.529 .008 .301 1.464 .003 44490.465 1.519 .002 .330 1.467 .002 .499 1.524 .002 44541.220 1.497 .002 .524 1.528 .001 .264 1.498 .004 .550 1.521 .001 .321 1.511 .005 44506.306 1.519 .004 .365 1.501 .003 .316 1.517 .003 .404 1.502 .008 .333 1.522 .002 44862.329 1.420 .004 .366 1.526 .004 .393 1.456 .003 .396 1.515 .003 44865.342 1.496 .002 .424 1.514 .002 44891.341 1.440 .003 .452 1.519 .002 44892.253 1.446 .004 44540.222 1.441 .001 44915.237 1.468 .003 -------------------------------------------------------- Table I b Photoelectric B observations -------------------------------------------------------- Hel. J.D. Hel. J.D. 2400000+ DeltaB Sigma 2400000+ DeltaB Sigma -------------------------------------------------------- 44473.421 1.678 .007 44540.371 1.630 .002 44484.356 1.702 .003 .339 1.646 .003 44490.456 1.692 .002 44547.233 1.678 .003 .490 1.694 .002 .272 1.673 .002 .517 1.700 .001 .335 1.689 .005 .541 1.696 .003 .372 1.687 .005 44506.343 1.692 .004 .417 1.671 .004 .376 1.696 .003 44862.347 1.614 .006 .416 1.689 .004 44865.373 1.650 .002 .443 1.686 .002 44891.357 1.601 .002 44540.234 1.618 .004 44915.258 1.639 .003 .277 1.621 .007 ------------------------------------------------------- Table I c Photoelectric U Observations ------------------------------------------------------- Hel. J.D. Hel. J.D. 2400000+ DeltaU Sigma 2400000+ DeltaU Sigma ------------------------------------------------------- 44490.441 2.315 .016 44540.289 2.190 .002 .478 2.280 .005 .320 2.222 .003 .508 2.301 .005 44541.244 2.260 .003 .531 2.279 .004 .286 2.238 .005 .558 2.271 .010 .378 2.249 .004 44506.356 2.288 .004 .329 2.241 .007 .386 2.268 .002 44862.370 2.202 .002 .406 2.267 .003 44865.395 2.252 .011 .433 2.260 .003 44891.399 2.173 .001 .464 2.268 .005 44915.270 2.214 .003 44540.245 2.184 .002 ------------------------------------------------------- [FIGURE 1] [FIGURE 2] This incipient shell episode is very interesting, since it could contradict a supposed 26-29 years periodicity of the phenomenon (Fracassini et al., 1977, Harmanec and Koubsky, 1981). M. BOSSI, G. GUERRERO, L. MANTEGAZZA, M. SCARDIA Osservatorio Astronomico di Brera via E. Bianchi n. 46 22055 Merate Italy References: Bossi, M., Guerrero, G., Mantegazza, L., 1977: Astron.Astrophys. Suppl. 29, 327. [BIBCODE 1977A&AS...29..327B ] Bossi, M., Guerrero, G., Mantegazza, L., Scardia, M., 1980: Astrophys. Spa. Sci. 72, 433. [BIBCODE 1980Ap&SS..72..433B ] Fracassini, M., Pasinetti, L.E., Pastori, L., 1977: Astrophys. Spa. Sci. 49, 145. [BIBCODE 1977Ap&SS..49..145F ] Guerrero, G., Mantegazza, L., 1978: Astron Astrophys. Suppl. 36, 471. [BIBCODE 1979A&AS...36..471G ] Harmanec, P., Koubsky, P., 1981: Proceedings I.A.U. Symp. No. 98, Munnich, in press. [BIBCODE 1982IAUS...98..315H ]