COMMISSION 27 OF THE I. A. U.
         INFORMATION BULLETIN ON VARIABLE STARS
                     Number 2225

                                  Konkoly Observatory
                                  Budapest
                                  1982 November 11

                                  HU ISSN 0374-0676



           IS UX Dra A CARBON BINARY STAR?


  The carbon star UX Dra, usually classified as a semiregular
variable, was observed photoelectrically at Brno Observatory
during the time period between August 1979 and October 1982.
Simultaneous high dispersion spectra of this star were taken
with the 2m telescope at the Ondrejov Observatory.
  The light curve obtained in three colour expresses a strong
regularity in alternating one deep and one shallow minima which
suggests the light changes of a photometric binary. The radial
velocity curve based on the measurements of details of the Swan
molecular bands C2(1,0) and C2(0,1) is in conformity with the 
hypothesis of the binary nature of UX Dra. The half-amplitude of the
radial velocity changes found is 2.2 km/s, the period is about
340 days, i.e. twice as long as the mean period declared for the
semiregular light changes of UX Dra. If UX Dra is really a 
photometric binary then the confrontation of both light and radial
velocity curves leads to the conclusion that the smaller and
warmer component of the system is occulted by a substantially
more massive carbon star during the primary minimum.
  Could anybody verify the alternation of the deep and shallow
minima in this star on the basis of some observations made
closely before 1979?





                 M. VETESNIK

        Department of Astronomy, Brno University
        61137 Brno, Czechoslovakia