COMMISSION 27 OF THE I. A. U.
        INFORMATION BULLETIN ON VARIABLE STARS
                     Number 1101

                                Konkoly Observatory
                                Budapest
                                1976 February 11

   Rosemary Hill Observatory, Department of Physics and Astronomy,

        University of Florida, Contribution No. 65.


        RADIO EMISSION FROM WOLF-RAYET BINARIES


   Three Wolf-Rayet binaries have been examined for radio emission with
the NRAO* three element interferometer. The Wolf-Rayet systems observed
were CV Ser (WC8 + B0:), V 444 Cyg (WN5 + O6), and HD 193793 (WC7p + O5).
Based on the infrared excesses and electron densities given by Hackwell,
et al. (1974), detectable radio emission was considered likely.
   The radio observations were made during October 18-25, 1975. The
stars were observed simultaneously at 3.7 cm (8085 MHz) and 11.1 cm (2695
MHz). The interferometer spacings used were 900, 1800, and 2700 meters,
At least 19 hours were spent observing each star.
   A radio source was observed to coincide with the optical position
of HD 193793. The radio position agrees with the AGK 3 position, allowing
for proper motion, to within 0.5 arc seconds. The radio source was unresolved, 
indicating an angular diameter of less than 0.5 arc seconds. The
observed flux densities for HD 193793 were 21.0 +-1.0 mJy** and 26.2 +- 1.1
mJy at 3.7.cm and 11,1 cm, respectively. During the time HD 193793 was
observed, October 23-25, no variability was observed within the sensitivity
limits of the observations. The daily mean flux density values repeat
to within 4 mJy. Short term variations, having a time scale of about
one hour and an amplitude of 8 mJy, can not be ruled out.
   No radio emission at either frequency was observed from either CV Ser
or V 444 Cyg. An upper limit for the radio emission for these stars is
approximately 2 mJy. Since radio emission from binary stars is highly
variable, radio emission from CV Ser and V 444 Cyg should not be discounted.



University of Florida         D.R. FLORKOWSKI
Gainesville, Florida 32611    S.T. GOTTESMAN

* Operated by Associated Universities, Inc, under contract with the National
Science Foundation.
** 1 mJy = 10^-29 W m^-2 Hz^-1

Reference:

Hackwell, J. A., Gehrz, R. D., and Smith, J. R. 1974, Ap. J., 192, 383 [BIBCODE 1974ApJ...192..383H ]