Commission 27 of the I.A.U.
         Information Bulletin on Variable Stars
                      Number 4




                                       Konkoly Observatory
                                       Budapest
                                       14 January 1962





   DISCOVERY OF OVERTONES AND RESONANCE OSCILLATIONS IN
       BETA CANIS MAJORIS AND IN BETA CEPHEI

      A thorough investigation on the radial velocity variation 
of Beta CMa has disclosed the existence in this star of
at least ten different oscillations. These are resp. the free
pulsations in the fundamental mode and in the first five overtones 
(P_O, P_1, ..., P_5) and the difference oscillations P_{i,i+2}
arising from the coupling between the P_i and the P_i+2 from
P_02 to P_35.
      The ratios P_i/P_0 are entirely consistent with the
theoretical predictions for the polytrope of index 3 and
GAMMA_1=1.53.
      Of the two periods that have been detected earlier the
longer one, 0d.2513003, appears to correspond to the free pulsation 
in the fundamental mode P_0, while the shorter one,
0d.2500246, is the period P_24 of the coupling term between the
second and the fourth overtones.
      The line broadening is connected with the pulsation
in the fundamental mode.
      A similar investigation carried out on Beta Cep has
lead to the discovery of 55 different oscillations, all with
measurable amplitudes. They are: the first ten overtones
P_l, P_2, ...,P_10, the difference oscillations P_{i,i+2} between
them (9 in number), the further difference oscillations P_{i,i+3}(8)


        
P_{i+4}(7), P_{i,i+5}(6), P_{i,i+6}(5),P_{i,i+7}(4), P_{i,i+8}(3),
P_{i,i+9}(2) and P_{i,i+10} (1).
      The corresponding amplitudes range from 20 km/sec for
the main oscillation to 0.8 km/sec for the smallest.
      The ratios P_i/P_0 for the first four overtones are
again those foretold by the theory for the polytrope of index
3 with GAMMA_1=1.52.
      The single period given in the GCVS corresponds to
the main oscillation which is P_24=P_0. So P_24 is at perfect
resonance with P_0, as was the case in Nu Eri.
      The absence of line broadening in this star is ascribed 
to the absence or the extreme weakness of the directly excited 
fundamental pulsation P_0.
      The results thus far obtained from the five stars
Theta Oph, Nu Eri, Beta Cep, Beta Cru and Beta CMa show a 
continuous increase of GAMMA_1 from 1.51 for the shortest main period
to 1.53 for the largest.
      Full results will be published in the Zeitschrift fur
Astrophysik.



                               A. van HOOF
                          University of Louvain
                                Belgium