COMMISSION 27 OF THE I. A. U.
           INFORMATION BULLETIN ON VARIABLE STARS
                        Number 2572

                                       Konkoly Observatory
                                       Budapest
                                       14 August 1984

                                       HU ISSN 0374 - 0676

       UNUSUAL LIGHT VARIATIONS OF THE CARBON STAR AFGL 2881

  We studied light variations of the infrared object AFGL 2881 (Price and 
Walker, 1976) on plates taken with the Schmidt telescope of the Radioastrophysical
Observatory. The finding chart published by Cohen and Kuhi (1977)
was used for identification of the optical counterpart of the object.
  The character of light variations of this carbon star turned out to be
rather unusual.
  At first, from June 1975 till Dec. 1978 (J.D. 2442572 - 2443858) the star
behaved as a long-period variable (Fig. 1). At the maximum light the red
magnitude mR was 10.8 +- 11.1, mV = 13.0 +- 13.4 and mB approx. 18 (the object
is visible only on one B-plate). At the minimum light mR= 13.0 +- 13.7, mV=15.0.
The three observed maxima give the following light elements

            Max = J.D. 2442690 + 560 E               (1)


                           [FIGURE 1]

 Figure 1. The mR light curve of the object AFGL 2881. "v" stands
 for observations below plate limit. Small arrows at the top represent
 the predicted dates of maxima.


   On plates taken later, however, the star was unexpectedly faint. On most
of the 13 red plates taken between Oct. 1979 and Oct. 1982 the star was below
plate limit, and never was seen brighter than mR = 14.4, even at phases 0.14
and 0.87 according to the equation (1). During the observing season 1983 when
exposures were made longer than previously, the star was observed declining
from mR = 14 at the beginning to mR = 16 at the end of the season.
  Thus our observations indicated that after Dec. 1978 the star AFGL 2881
faded in red light by two to three magnitudes in comparison to the earlier
mean light curve.
  More details on the variability of the AFGL 2881 will be given in a
forthcoming paper in the Investigation of the Sun and Red Stars.
   It would be important to know how rapidly the star faded and what was
its photometric behaviour during the long interval of faint light. It is
highly desirable to look through suitable red or V-plates, at least those
taken after 1978 in plate collections of other observatories. It would be
also interesting to compare the optical variations with those in infrared.


                             [FIGURE 2]

 Figure 2. The finding chart for AFGL 2881 (R.A. = 22h 16.5m, Decl.=
 +43d 32', 1950) and comparison stars. The anonymous red star (see
 text) is marked with a circle.


Not less interesting would be to follow possible return of the star to its
previous bright condition.
  Probably, the star AFGL 2881 faded because of additional dust expelled
from its surface as in the case of the variable carbon star HV 2379 (Bessell
and Wood, 1983).
  On the objective prism plate taken in Aug. 1974 we found another very
red star 2.2 arcmin south of the AFGL 2881. It is approx. 30 arcsec north of
comparison star No.11 (Figure 2). On this particular plate the anonymous red
star turned out to be about 1.5 mag brighter than AFGL 2881, contrary to that
seen on direct plates taken later. Positions of both red stars support identity
of AFGL 2881 with the star No.3125 in the General Catalogue of Cool
Carbon Stars (Stephenson, 1973), or with the star Case 749 (Blanco, 1956),
suggested by Altamore et al. (1980). On our plates in most cases this 
anonymous red star is below plate limit. However, long-period variations with
preliminary cycle length of about 440d for this red star are suspected.


                       A. ALKSNIS and A. RUDZINSKIS
                      Radioastrophysical Observatory
                      Latvian Academy of Sciences
                        Riga, Latvia, U.S.S.R.

References :
Altamore, A., Smriglio, F., Bussoletti, E., Corsi, C.E. and Rossi, L.: 1980,
   Astrophys. Space Sci., 72, 159. [BIBCODE 1980Ap&SS..72..159A ]
Bessell, M.S. and Wood, P.R.: 1983, Mon. Not. R. astr. Soc., 202, 31P. [BIBCODE 1983MNRAS.202P..31B ]
Blanco, V.M.: 1958, Astrophys. J., 127, 191. [BIBCODE 1958ApJ...127..191B ]
Cohen, M. and Kuhi, L.V.: 1977, Publ. astr. Soc. Pacific, 89, 829. [BIBCODE 1977PASP...89..829C ]
Price, S.D. and Walker, R.G.: 1976, The AFGL four colour infrared sky survey;
   AFGL-TR-76-0208. [BIBCODE 1976afci.book.....P ]
Stephenson, C.B.: 1973, Publ. Warner and Swasey Obs., 1, 79. [BIBCODE 1973gcss.book.....S ]