COMMISSION 27 OF THE I. A. U.
         INFORMATION BULLETIN ON VARIABLE STARS
                    Number 3106


                                  Konkoly Observatory
                                  Budapest
                                  29 October 1987

                                  HU ISSN 0374 - 0676



              A NEW RED VARIABLE STAR

During the photographic photometry of the H-alpha emission stars in the 
region of the open cluster Tr 37 (Kun, 1986) a new variable star was found on
the plates taken with the 60/90/180 cm Schmidt telescope of Konkoly Observatory. 
The coordinates of the star (see the identification chart) are:

          alpha(1950)=21h40m56.3s, delta(1950)=+57d06'28.5".

Variability of the star was established from the following observations:
   
   Date of obs.   JD            Measured magnitude
                                 R    V     B
   28 June 1968 2440035.49        -   17.0   -
   31 Oct. 1972 2441622.43      13.2  -
   20 Oct. 1985 2446359.39      14.7  18.0  invisible
   16 June 1986 2446597.49      -     15.5  18.6
   14 Sep. 1986 2446687.49      -     15.0  -


                            [FIGURE 1]

 Figure 1. The identification chart. North is at the top and east is to 
 the left. The size of the chart is 15' X 15'.


The photographic R, V and B magnitudes were determined using Lichtbuer's
(1982) photoelectric sequence. The magnitudes listed here were averaged
from two plates taken on the same night. A red-filtered objective prism
plate obtained on 13th August 1986 shows this star brighter than the star
which is situated immediately to the west of it whereas the Palomar Observatory 
Sky Survey red print shows the reverse situation. Our objective prism
plate shows a TiO band characteristic for an M type star as well.
An IRAS point source is to be found at the coordinates RA(1950)=21h40m
59.1s and D(1950)=+57d06'20", and it is thought that this infrared emission
might well come from the red star. We cannot, however, exclude the possibility 
that the far infrared source is the neighbouring star which, according 
to Marschall and van Altena (1987), is a member of Tr 37 and may thus
be a pre-main-sequence star having infrared excess.
  Obviously this limited amount of information is insufficient for 
characterizing the nature of the star. The red colour and the large amplitude
suggest that the new variable is probably a Mira type star, similarly to
the red variables found in this region by Friedemann et al. (1977) and by
Pfau and Friedemann (1980). The most important questions to be answered 
include the determination of the period of the light variation if it exists,
and to decide whether the star is a member of Tr 37 or not. Examination of
the archival plate material of other observatories would probably shed more
light on the nature of this star.


                               M. KUN

                               Konkoly Observatory
                               H-1525 Budapest,
                               P.O. Box 67, Hungary


References:

Friedemann, C., Gurtler, J. and Pfau, W.: 1977, Astron. Nachr. 298, 327. [BIBCODE 1977AN....298..327F ]
Kun, M.: 1986, Astrophys. Sp. Sci. 125, 13. [BIBCODE 1986Ap&SS.125...13K ]
Lichtbuer, P. C.: 1982, Vatican Obs. Publ. 2, 1. [BIBCODE 1982VatOP...2....1C ]
Marschall, L. A. and van Altena, W. F.: 1987, Astron. J. 94, 71. [BIBCODE 1987AJ.....94...71M ]
Pfau, W. and Friedemann, C.: 1980, Astron. Nachr. 301, 69. [BIBCODE 1980AN....301...69P ]