COMMISSION 27 OF THE I. A. U.
          INFORMATION BULLETIN ON VARIABLE STARS
                       Number 897

                                    Konkoly Observatory
                                    Budapest
                                    1974 June 15



  PHOTOELECTRIC OBSERVATIONS OF THE FLARE ACTIVITY OF RED DWARFS


    In 1969-1973 photoelectric observations have been carried out
 at the Crimean Astrophysical Observatory for a number of dM and dMe
 stars. Before there were no exhaustive informations on the flare 
 activity of these stars. The patrol photoelectric observations at the
 64 cm meniscus telescope are in a photometric system close to B, and
 those at the 70 cm reflector to U. Results of the observations are
 given in the Table. In the columns of this Table are inserted: 
 1) Serial number of the star from catalogue(1); 2) designations from other
 catalogues; 3) apparent magnitudes; 4) absolute magnitudes; 5) spectral
 types; 6) durations of the photoelectric patrol (hours) in B;
 7) numbers of flares recorded in B; 8) duration of the photoelectric
 patrol hours in U; 9) numbers of flares recorded in U.
    The periods of the photoelectric patrol of the stars are shown
 in Fig. 1. Open rectangulars note periods of observations in B, the
 solid rectangulars those, in U. The triangles mark the moments of the
 registered flares.
                           

    1       2             3      4      5        6      7   8      9
    N(1)                  V     M_V             T_B    n_B T_U    n_U
a   29.1    FF And       10m38  8m7    dM0e      5h8    0  10h3    1
b   182                   9,6   8,8    dMIe     28,5    0   6,3    1
c   207.1   V 371 Ori    11,68 10,8    dM3e     15,3    0
d   447                  11,10 13,50   dM5      29,7    0
e   526     BD+15d2620    8,50 10,02   dM4Ye    27,1    0
f   644A    V1054 Oph     9,76 10,79   dM4,5e   36,0    4
       B                  9,8  10,8    dM4,5e
g   905                  12,29 14,80   dM6e     17,0    0

    The light curves of the observed flares in relative intensities,
 i= I_f-I_o/I_o versus UT are shown in Fig. 2, I_o is the intensity deflection
 due to the normal flux from a quiescent star, I_f is that during the
 flare. For each flare the following data, according to (2), are given:
 P= Integral( i dt), the equivalent duration of the flare in minutes, and 
sigma/I_o,
 where sigma is the standard deviation in I_o.
           
                          N.I. SHAKHOVSKAYA
                       Crimean Astrophysical Observatory

(1.) W. Gliese, Veroff.astr.Rechen.Inst.
  Heidelberg, Nr. 24, 1971. [BIBCODE 1971VeARI..24....1G ]
(2.) A.D. Andrews, P.E. Gershberg, V.S. Oskanjan,
  IBVS, 1969, No. 326. [BIBCODE 1969IBVS..326....1A ]

                       [FIGURE 1]

                       [FIGURE 2]