COMMISSION 27 OF THE I. A. U.
         INFORMATION BULLETIN ON VARIABLE STARS
                      Number 1312

                                   Konkoly Observatory
                                   Budapest
                                   1977 July 28




      EVIDENCE OF MASS EJECTION FROM Beta PERSEI (ALGOL)




   Observational evidence of mass ejection has been detected in
the ultraviolet spectrum of beta Per obtained from the Balloon-borne
Ultraviolet Stellar Spectrometer (BUSS). The observations were
obtained at JD 2442330.674 in the 24 Angstrom spectral range centered
at 2800 Angstrom, which includes the Mg II resonance doublet at 2795.523
and 2802.698 Angstrom and their respective subordinate lines at 2797.989
and 2790.768 Angstrom. The spectrometer entrance slit had a width 
corresponding to 1/4 Angstrom. The wavelength scale was determined to an
accuracy of 1/4 Angstrom.
   The resonance lines are narrow and deep and the subordinate
lines are markedly pronounced. Both features are analogous to
those seen in shell stars. The deep subordinate lines are also
characteristic of high luminosity objects (class I or II) in
late B spectral types.
   To be noted are the shortward-shifting (by 3/4 Angstrom) of the
entire set of Mg II lines, as also seen in the shell star zeta Tau
(Morgan, Kondo and Modisette, Ap.J., 1977 September 1). The 
orbital phase of beta Per at the time of observation was 0.314; as
K1 = km/s, the orbital velocity of the primary at that time
(-17.6 km/s) cannot account for the shifting of the Mg II
lines. One possible explanation is that all Mg II lines originate
from an optically thick expanding shell. (The "photospheric"
Mg II lines are theoretically thought to originate in the outermost 
layers.) The outflowing matter might have been undergoing
an acceleration in the fashion of solar wind. If so, the observed 
expansion velocity of the shell, which is about 80 km/s,
does not preclude the possibility that the mass was being lost
from the binary system.
   The Copernicus observations of the Mg II lines, obtained by
Chen and Wood (1976, MNRAS, 176, 5P) in January 1974 at phases
between 0.845 and 0.093, did not show any measurable shifting
of these lines beyond what can be accounted for as the radial
velocity of the primary. A tentative explanation of the apparent
difference is that the 1974 October 10 BUSS observations were
obtained when a significant amount of mass was flowing out of
the primary. Had appropriate observations been made at about
the same time, Algol might have appeared as an active radio
source and a weak X-ray source. Algol has been identified as an
incipient radio source by Hjellming, Wade and Webster (1972,
Nature Phys.Sci., 238, 52) and as an occasional weak X-ray source
by Schnopper et al. (1976, Ap.J. 210, L75). Alternatively, it is
possible that a steady-state, non-uniform flow produces different 
Doppler-shifts at different phases.
   The BUSS spectrum of beta Per (B8 V + K IV) is shown together
with those of two comparison stars beta Lib (B8 V) and alpha Leo (B7 V).
Background has been subtracted in these plots. The spectral 
classification for beta Per is by Hill et al. (1971, Ap.J., 168, 443).




   YOJI KONDO                  J.L. MODISETTE
   SC23                        T.H. MORGAN
   Johnson Space Center        Houston Baptist University
   Houston, TX 77058, U.S.A.   Houston, TX 77036, U.S.A.


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