COMMISSION 27 OF THE I. A. U.
           INFORMATION BULLETIN ON VARIABLE STARS
                       Number 3035


                                       Konkoly Observatory
                                       Budapest
                                       17 June 1987

                                       HU ISSN 0374-0676


             VARIABILITY OF SOME S! STARS

   In IBVS No. 1490, D. Hoffleit suggested that almost all the S! stars in
Stephenson's (1976) "A Catalogue of S Stars" may be variable. I examined
the variability of the stars on the photographs taken since then with 8cm
and 10cm cameras for brighter stars, and mostly with 18cm Schmidt camera,
using Tri-X film and the yellow-green filter to get visual magnitude. The
names and positions of the stars are as follows, and all the stars are
found to be SR type variable.

Stephenson  Const.         R.A. (1950) Decl.
Cat. No.

S 10         Cas           0h43m54s +63 39.8
S123         Aur           5 56  4  +35  8.0
S139         Aur           6 11 12  +28  8.9
S223         Mon           7 18 22  - 7 42.5
S687         Cep          21 29 23  +61 20.2
S727         And          23 13  5  +50  2.5


The position of S10 is measured by the writer, identifying the star by
personal communication with Dr. Stephenson. The positions of other stars
are from Stephenson's (1984) Catalogue, 2nd edition.

   1) S10 Cas
   The star was measured on about 120 photos in only three observational
years, as the star was out of the field in other seasons. The star seems
to be SRb variable with the period of probably 210 days. The range is
12.3-14.2v. The light curve is shown in Figure 1.


                           [FIGURE 1]
                           [FIGURE 2]
                           [FIGURE 3]
                           [FIGURE 4]
                           [FIGURE 5]
                           [FIGURE 6]


   2) S123 Aur
   This star was measured on more than 170 photos taken in 1978-1987, and
found to be possibly SRa type with the range 11.5-13.0v. The following
elements are obtained:

        Max. = J.D. 244 3870 + 155d * E

In Figure 2, the light curve in only recent years is shown.

   3) S139 Aur
   This star was measured on 250 photos taken in 1979-1987, and it possibly 
is SRb type with the period of probably 175. The range was
12.4-13.8v so far.

   4) S223 Mon
   This star was measured on 130 photos taken in 1979-1987, and it is
possibly SRb variable with the range 10.2-11.5v and the period of 194d.
The following elements are obtained:

        Max. = J.D. 244 4230 + 194d * E

The light curve in three observational periods are shown in Figure 4.

   5) S687 Cep
   This star was measured on 230 photos taken in 1979-1987. The star
shows very regular variation with the period of 193d and the range of
11.8-13.4v. It is SRa type and the elements obtained are as follows:

         Max. = J.D. 244 3975 + 193.3d * E

In Figure 5 is shown the light curve in recent years.

   6) S727 And
   This star was measured on more than 370 photos taken in 1979-1987.
It is rather irregular than other stars, but it would be SRb type with the
period roughly from 88 to 104 days. The range was 10.4-11.3v so far.
Figure 6 shows the light variation in recent years.



                             M. HURUHATA
                             Hodozawa 88
                             Gotenba-shi,
                             412 Japan

References:

   Stephenson, C.B., 1976, Publ. Warner and Swasey Obs. Vol. 2, No. 2. [BIBCODE 1976PW&SO...2...21S ]
   Stephenson, C.B., 1984, Publ. Warner and Swasey Obs. Vol. 3, No. 1. [BIBCODE 1984PW&SO...3....1S ]