COMMISSION 27 OF THE I. A. U.
         INFORMATION BULLETIN ON VARIABLE STARS
                     Number 2143

                                 Konkoly Observatory
                                 Budapest
                                 1982 May 13

                                 HU ISSN 0374-0676




        PHOTOELECTRIC FLARE OBSERVATIONS OF GLIESE 867 B




  The flare star Gliese 867 B was observed on 1 October 1981, as part of an
international programme (Butler and Rodono 1981). The suggested interval for
monitoring the star Gliese 867 B was from 17:30 to 20:00 UT. We were able to
secure continuous observations of the star from 16:12 to 19:36 UT through the
104-cm Sampurnanand reflector equipped with thermo-electrically cooled
EMI 6094S photomultiplier tube. The star was monitored through the
U and B filters of Johnson and Morgan system. The monitoring interval through
the U filter extended from 18:51 to 19:36 UT while through the B filter the
intervals ranged from 16:12 to 16:31 UT and from 16:42 to 18:47 UT. Two
flares were recorded during the observations through the U filter but no
flare was present in the B filter observations. The stellar intensity was
measured against sky background only without observing any comparison star.

                            [FIGURE 1]
                            [FIGURE 2]

  The light curves which represent the flow of excess radiation I_f radiated
at a given moment expressed in units of flow I_0 from the star in normal
non-excited state, with time, are given in Figures 1 and 2 (flare No. 1 and 2).
These light curves show that they are Type I (Gurzadyan, 1980) flare events
and no spikes are associated with them. Flare 1 is unusual at its maximum
and the rate of development is also slow as compared to usual UV Ceti type
flares. The light curve and the rate of development of flare 2 is normal of
its kind.


                                     Table I
Characteristics of the flares on Gliese 867 B (dM 4e: V = 11.8m; B-V = 1.61m
d = 8.3 pc)
UT        Flare duration  I_f+0/I_0  Deltam_U   P      F(z)   Energy     Total emission
max       (in minutes)                         (min)           released   during the
          Before   After                                       at flare   event
            max     max                                        max.
          t_b      t_b                                         10^29 ergs/s 10^30 ergs/s
19h17.9m  0.50     1.6     2.05      0.78    0.82     2.22     0.45       1.08
19h32.6m  0.25     2.8     2.40      0.95    0.89     2.40     0.52       1.17

  Flare characteristics are given in Table I. The equivalent time of flare
(P) was planimetered as the area under the light curve, to derive the total
energy radiated by the flare event.





           B.B. SANWAL

           Uttar Pradesh State Observatory,
           Manora Peak, Naini Tal-263129,
           India





References:

Butler, J. and Rodono, M. 1981, Private Communication.
Gurzadyan, G.A., 1980, p 9, Flare Stars, Pergamon Press. [BIBCODE 1980flst.book.....G ]