COMMISSION 27 OF THE I. A. U.
                INFORMATION BULLETIN ON VARIABLE STARS
                            Number 3576

                                                       Konkoly Observatory
                                                       Budapest
                                                       12 March 1991

                                                       HU ISSN 0374 - 0676


          A VERY INTERESTING VARIABLE V627 Cas (AS 501):
               BRIGHTENING FORECAST FOR MID-1991


   Herbig and Rao (1972) included the object AS 501 (designated as V627
Cas) from the list of Merrill and Burwell (1950) into the second catalogue
of young stars with a sense of doubt. The spectral class of the star is 
around M2-M4 with H, TiI, FeI and FeII emission lines. It shows marked 
overabundances in the UV and IR emission and high level of linear polarization,
OH and H2O maser emission has been also found in the direction toward this
object. The problems connected with the uncertainty in the evolutionary status 
of V627 Cas were earlier discussed in details by Derviz and Kopatskaya
(1981), Kolotilov (1988) and Bergner et al. (1988).
   The UBVRIK observations were carried out in 1974-1984 by Kopatskaya
(1986) did not show any periodicity in the optical light variability. The
results of UBVRIJHKLM photometry of V627 Cas carried out in 1983-1988 are
published in the papers of Taranova and Yudin (1987), Goransky and Kolotilov
(1988) and Bergner et al. (1988). In particular Kolotilov (1988) suspected
the presence of an optical burst with the period close to 900 days.
   In 1988-1990 we proceeded the optical and IR photometry of V627 Cas,
the results of which are to be published elsewhere. Figure 1 shows the light
curve of V627 Cas in the V band folded with the period of 900 days through
the whole bulk of 1983-1990 data. The maxima were observed in the end of
1983, in mid-1986 and in the end of 1988, the next brightening is forecasted
for mid-1991. The brightness of V627 Cas in 1983-1990 in the IR bands did
not show any visible changes (DeltaJ<=0.1m).
   Let us note that, in addition to the photometric measurements, one of
the authors (A.S.M.) obtained the record of V627 Cas on the 6-m telescope
of the Special Astrophysical Observatory in the wavelength range lambdalambda3816-
5664 Angström. The observations were made in January 1989. Primarily, numerous
TiO absorption bands and the H_beta emission are evident here. Later, in August
1989 the record of the spectrum in the wavelength range 4000-7500 Angström was
obtained by Mendoza et al. (1990). It shows the TiO bands and the H_alpha
emission.


                                 [FIGURE 1]


   Earlier Kolotilov (1988) undertook an attempt to classify V627 Cas as
a nova-like symbiotic star. In this case the periodicity of the light curve
could have been associated with the orbital period of the system. However,
V627 Cas differs from the known symbiotic stars by a number of parameters.
   On the other hand, V627 Cas cannot be classified as a young star of
T Tau type. Particularly, on the IR color diagrams (in the range 2.2-60 micro m)
it coincides with the OH/IR stars. Besides, if we regard it as a member of
young stellar association near DI Cep, the bolometric flux from V627 Cas
calculated with respect to the IRAS data being F_bol=~1.4*10E-7 erg/cmE2 sec
is about 30 times as high as the one from DI Cep, belonging to typical T Tau
stars.
   Thus, the evolutionary status of V627 Cas still remains uncertain.
Formally, it is possible to interpret the available observational data 
assuming that we observe a peculiar red giant and a young star in the same 
direction. In the opposite case we are probably dealing with a symbiotic 
system, where the hot component is showing very violet (DeltaU=~0.6m at B
~constant), or very blue (DeltaB=~0.5m at V ~constant) emission bursts.
   Having noticed peculiar characteristics of the variable V627 Cas and
forecasting its brightening, we are calling the astronomical community for
various patrol observations of this star.


E.A. KOLOTILOV               A.S. MIROSHNICHENKO              B.F. YUDIN

Crimean Laboratory of        Main Astronomical Observatory    Shternberg State
the Shternberg State         U.S.S.R., 191140,                Astronomical
Astronomical Institute,      Leningrad, Pulkovo               Institute,
U.S.S.R., 334413, Nauchny,                                    U.S.S.R., 119899,
Crimea                                                        Moscow,
                                                              Universitetskyi
                                                              prospect, 13



References:

Bergner, Yu.K., Miroshnichenko, A.S., Yudin, R.V., Yutanov, N.Yu.,
       Kuratov, K.S. and Mukanov, D.B.: 1988, Pis'ma Astron. J., 14, 616. [BIBCODE 1988PAZh...14..616B ]
Derviz, T.E., Kopatskaya, E.N.: 1981, Pis'ma Astron. J., 7, 168. [BIBCODE 1981PAZh....7..168D ]
Goransky, V.P., Kolotilov, E.A.: 1988, Variable Stars, 22, 667. [BIBCODE 1988PZ.....22..667G ]
Herbig, G.H., Rao, K.N.: 1972, Astrophys. J., 174, 401. [BIBCODE 1972ApJ...174..401H ]
Kopatskaya, E.N.: 1986, Dissertation, Leningrad University.
Kolotilov, E.A.: 1988, Astrofizika, 29, 458. [BIBCODE 1988Afz....29..458K ]
Mendoza, E.E., Rolland, A. and Rodriguez, E.: 1990, Astron. Astrophys,
       Suppl. Ser., 84, 29. [BIBCODE 1990A&AS...84...29M ]
Merrill, P.W., Burwell C.G.: 1950, Astrophys. J., 112, 72. [BIBCODE 1950ApJ...112...72M ]
Taranova, O.G., Yudin, B.F.: 1987, Astron. Tsirkular, No. 1501, 7. [BIBCODE 1987ATsir1501....7T ]