COMMISSION 27 OF THE I. A. U.
        INFORMATION BULLETIN ON VARIABLE STARS
                    NUMBER 730

                                  Konkoly Observatory
                                  Budapest
                                  1972 October 30


            FLARE ACTIVITY OF Gl 669 A


   The double system Gl 669 AB (= Ross 867 + Ross 868) 
consists of the 11.3m_v dM4e and 12.8m_v dM5.5e stars separated
by about 16". Both stars exhibit the Ca 11 H and K lines and
the Balmer series in emission. The flare activity of Gl 669 B
(Ross 867) was observed photoelectrically in U-band by Kunkel
[1]. Gl 669 A was observed photoelectrically in V-band for a
total of 35.6 hours by Roques [2] but during that time no
flares were registered.
   Our photoelectric observations of Gl 669 A were carried
out on the 64 cm meniscus telescope at the Crimean Observatory 
in photometric system close to B. The star was observed for
a total of 12.5 hours during the period from 3 June to 5 July
1972, and one flare was registered. The flare characteristics
according to [3] are the follows:

----------------------------------------------------------------
  Date         UT       I_0+f - (I_0/I_0)   sigma/I_0   P_B(min)
               max    
----------------------------------------------------------------
 17.6.1972   22h15.8m          1.00           0.05       1.60
----------------------------------------------------------------

The light curve of the flare in Fig. 1 has relative intensity
i_B=I_0+f - I_0/I_0 as ordinate and Universal Time as abscissa.
   The discovery of the flare activity of Gl 669 A confirms
the conclusion [4,5] that the previous hypothesis, according
to which only the fainter component of a binary UV Ceti type
is always the flare star, is not valid.

                     [FIGURE 1]

During 1970 - 71 four spectrograms with dispersion 155 A/mm
in the spectral range 5700-7000 AA have been obtained with
the 2.6 m reflector at Crimean Observatory. The equivalent
widths of the H-alpha emission line - W_Halpha (A)-range on 
these spectrograms from 1.4 to 2.1 A (the probable error of
W_Halpha obtained from one spectrogram is equal to 25%). This
value is 6-7 times less than W_Halpha in the quiet spectra of
the most active flare stars EV Lac, AD Leo, YZ CMi, UV Cet [6].
According to the correlation between the emission intensity
in quiet state spectra and the flare activity level of the
flare stars [6], the activity level of the Gl 669A is 
approximately 100 times less compared to the very active flare
stars.




                     N.I. SHAKHOVSKAYA
               Crimean Astrophysical Observatory
                        W. SOFINA
                   Tomsk State University


    References:

1   W.E. Kunkel, An Optical Study of Stellar Flares, Austin, 1967.
2   P.E. Roques, PASP 67, p 34, 1955. [BIBCODE 1955PASP...67...34R ]
3   A.D. Andrews, P.F. Chugainov, R.E. Gershberg, V.S Oskanian,
    IBVS No. 326, 1969.
4   A.N. Kulapova, N.I. Shakhovskaya, Izvestiya Crimean Astrophys.
    Obs. 49 (in press). [BIBCODE 1974IzKry..49...65K ]
5   F.N. Owen, B.W. Bopp, T.J. Moffet, F.J. Lazor, Astrophys.Lett.
    10, No. 1. p 37. 1972. [BIBCODE 1972ApL....10...37O ]
6   R.F. Gershberg, N.I. Shakhovskaya, IAU Colloquium No. 15,
    Veroffentlichungen der Remeis Sternwarte, Bamberg, Bd IX,
    No. 100, p 126, 1971. [BIBCODE 1971ndnf.coll..126G ]