COMMISSION 27 OF THE I. A. U.
         INFORMATION BULLETIN ON VARIABLE STARS
                     Number 2215

                                    Konkoly Observatory
                                    Budapest
                                    1982 October 21

                                    HU ISSN 0374-0676


           HD 185510: A NEW VARIABLE STAR


   Because Bidelman and MacConnell (1973) reported Ca II H and K emission,
we suspected HD 185510 might be an RS CVn binary and therefore might show
the photometric wave characteristic of most stars of that type. According
to their table VII, mv = 8.1m and the spectral type is K0 III/IV.
  Henry, observing with the No. 4 16-inch Cassegrain at Kitt Peak, 
obtained data on 3 nights between JD 2444716.9 and 2444719.9. Henry and
Sherlin, observing with the 48-inch Newtonian at Cloudcroft, obtained data
on 6 nights between JD 2444872.6 and 2444893.6 and on 11 nights between
2445115.9 and 2445153.9. All observations were made in V with BD - 6deg5222
as the comparison star. The individual differential magnitudes, corrected
for differential extinction and transformed differentially to V of the UBV
system, have been sent to the I.A.U. Commission 27 Archive for Unpublished
Observations of Variable Stars (Breger 1979), where they are available as
file no. 106.
  Examination of our data showed immediately that HD 185510 is variable,
with an amplitude of DeltaV = 0.20m. We had difficulty finding one period which
would combine all of the data into a light curve which had a smooth shape
and no discrepant points. As the figure below shows, the period does seem
to be around 25 days. This is a plot of the nightly means of the second
group of Cloudcroft data, where DeltaV is in the sense variable minus 
comparison.

  Additional photometry should be obtained in order to determine the
photometric period accurately and see if all of our data can be phased 
together properly. We have been in communication with Luis Balona and T.
Lloyd Evans of the South Africa Astronomical Observatory, who tell us they
are obtaining spectroscopic and photometric observations of this star (and
all of the stars in table VII of Bidelman and MacConnell). If radial 
velocity measures indicate HD 185510 is a binary system with an orbital period


                               [FIGURE 1]


around 25 days, then it would be a long-period RS CVn binary by the 
definition of Hall (1976).


                       GREGORY W. HENRY
                       STEPHEN MURRAY

                       Cloudcroft Observatory
                       Cloudcroft, New Mexico 88317

                       DOUGLAS S. HALL

                       Dyer Observatory
                       Vanderbilt University
                       Nashville, Tennessee 37235





References:

Bidelman, W. P. and MacConnell, D. J. 1973, A. J. 78, 687. [BIBCODE 1973AJ.....78..687B ]

Breger, M. 1979, I.B.V.S. No. 1659.

Hall, D. S. 1976, I.A.U. Colloq. No. 29, 287. [BIBCODE 1976ASSL...60..287H ]


                       [DATAFILE 1]