COMMISSION 27 OF THE I. A. U.
            INFORMATION BULLETIN ON VARIABLE STARS
                           NUMBER 44


                                          Konkoly Observatory
                                          Budapest
                                          29 February 1964


                      DETERMINATIONS WANTED
                      OF THE GAMMA-VELOCITY
                    OF BETA CEPHEI IN 1964-67

     Beta Cep has been reported by B. Smith (1) to be a spectroscopic 
binary with the elements:

     (K_1) sin i = 16.0 km/sec, e = 0.66

     omega = 187deg, P = 50 years.

     The binary nature of the star and Smith's period are also
mentioned in the second edition of Kukarkin and Parenago's "General
Catalogue of Variable Stars".

     The reality of this period was however called in question by
Struve (2), and it is easy to show that the whole set of elements is not
self-consistent. The mass-function, for instance, admits only a
maximum orbital velocity of 11 km/sec for the period and the
eccentricity given, and for an assumed mass of 20 M_sun (chosen
deliberately high) and a mass ratio = 2 (which seems not exaggerate,
since the secondary is invisible). This excludes Smith's value for the
projected orbital velocity.

     But Smith's value for (K_1) sin i was based on a few very low
gamma-velocities determined at Yerkes and Poulkovo in the years
1914-17. Since then 50 years have elapsed, hence it would be desirable
to follow the run of the gamma-velocity in the course of this and the
coming years.

     The interest of accurate determinations of the orbital
elements of Beta Canis Maioris stars which are at the same time
members of binary systems lies in the fact that in this case the mass
function enables one to make a fair estimate of the probable inclination
of the orbital and hence of the equatorial plane. This in turn enables
one to derive the probable velocity of rotation. And the knowledge of
the real velocity of rotation provides an experimental test of the
soundness or the incorrectness of some recent interpretations of the
beat phenomena observed in those stars. (3) (4) (5).


                                            A. VAN HOOF
                                       Astronomical Institute
                                        University of Louvain.
                                              Belgium



                  References

(1) B. Smith, Astroph. Journ., 98, 82, 1943. [BIBCODE 1943ApJ....98...82S ]
(2) O. Struve, D.H. McNamara, S. M. Kung and C. Beymer, id., 118, 39,
    1953, [BIBCODE 1953ApJ...118...39S ]
(3) S. Chandrasekhar and N. R. Lebovitz, id., 136, 1105, 1962. [BIBCODE 1962ApJ...136.1105C ]
(4) E. Bohm-Vitense, Publ. Astr. Soc. Pacific, 75, 154, 1963. [BIBCODE 1963PASP...75..154B ]
(5) A. van Hoof, Zeitschr. f. Astroph., in print.