COMMISSION 27 OF THE I.A.U. INFORMATION BULLETIN ON VARIABLE STARS Number 1407 Konkoly Observatory Budapest 1978 April 3 GLIESE 867 - A NEW FLARE-STAR SYSTEM Gliese 867 is a visual double star, both components of which are classified dMe (Dyer, 1954). Kunkel (1975) has included both stars in his list of known flare stars solely on the basis of their emission-line spectra (private communication). Bopp and Espenak (1977) have forwarded evidence for photometric variations in G867A. We confirm here that both G867A and B flare and that G867A undergoes significant night-to-night variations. Observations were carried out on the 0.75 meter reflector at the South African Astronomical Observatory using a high-speed pulse-counting photometer belonging to the University of Cape Town's Department of Astronomy. The latter was equipped with an Amperex 56DVP photomultiplier tube and glass filters approximating to the Johnson UBV system. For further details of the instrumentation see Nather and Warner (1971). G867A was monitored on six nights totalling 13.1 hours. Two flares were recorded one of which was preceded by a precursor. Details of the observations are given in Table 1(a). Table 1(b) gives results of observations of G867B totalling 6.6 hours, in which time twenty-one flares were observed. Light curves for these flares will be published elsewhere. G867A was also compared on four nights in U, B and V to a nearby 10m star y(alpha (1950) ~22h35m.2, delta (1950) ~-20d42.7'). This star was checked against HD214380 for constancy. No variations of amplitude greater than 0m.003 are indicated. Results are given in Table 2 as differential magnitudes in the sense DeltaV'= V'(y)-V' (G867A) and are in an instrumental system, untransformed to Johnson UBV. Night-to-night variations are confirmed but our results show a tendency to be redder in (B-V) when brighter in V rather than the reverse as found by Bopp and Espenak (1977). G867 is a particularly interesting flare star. Component B was extraordinarily active during the period of our observations. Component A is also known to be a 4.1 day spectroscopic binary, both components of which are of the same spectral type. (Herbig and Moorhead, 1965). One, however, is considerably stronger in emission than the other. It would be of interest to determine whether one or both members of G867A contribute to the flaring and in what proportion. Further study of the G867 system is now being planned. Application has been made for telescope time during August/September 1978. Observers interested in undertaking observations at this or another time could contact the undersigned with a view to making a coordinated effort. P. BRENDAN BYRNE Armagh Observatory Armagh BT61 9DG N. Ireland References: Bopp, B.W. and Espenak, F., Astron. J., 82, 916 (1977) [BIBCODE 1977AJ.....82..916B ] Dyer, E.R., Astron. J., 59, 218 (1954) [BIBCODE 1954AJ.....59..218D ] Herbig, G.H. and Moorhead, J.M., Astrophys. J., 141, 649 (1965) [BIBCODE 1965ApJ...141..649H ] Kunkel, W.E., "Variable Stars and Stellar Evolution", IAU Symp. No. 67, Ed. V.E. Sherwood and L. Plaut., D. Reidel, Holland (1975) p. 15 [BIBCODE 1975IAUS...67...15K ] Nather, R.E. and Warner, B., Mon. Not. R. Astron. Soc., 152, 209 (1971) [BIBCODE 1971MNRAS.152..209N ] Table 1(a) - G867A Date Time of Observation Flares Comment (U.T.) If-I_0/I_0 Begin End Time of 3sigma/I_0 Integ- Colour General Peak ration 1977 Oct. 25 18.20.12 18.43.32 2s U only 18.54.29 19.20.09 " " 19.28.54 19.59.54 " " 20.10.51 20.46.31 " " 20.54.29 20.58.19 20.57.05 0.404 0.036 " " Precursor? 21.00.25 21.05.41 21.03.45 0.871 0.036 " " 21.07.12 21.25.13 " " 21.33.42 22.20.14 " " Oct. 26 18.13.20 18.36.20 " " 18.46.27 19.27.47 " " 19.35.26 20.12.30 " " 20.19.53 20.56.33 " " 21.03.57 21.37.17 " " 21.44.08 22.15.08 " " 22.22.56 22.38.50 " " Oct. 28 19.15.50 19.36.15 3s " 19.41.13 21.20.07 20.55.12 0.310 0.011 " " 21,22.28 21.33.52 " " Nov. 18 18.25.25 19.01.00 2s UB&V each colour 19.13.20 19.38.00 " " 19.40.34 19.58.10 " " Nov. 19 18.34.31 18.35.34 3s " each colour 18.37.26 20.15.00 " " Nov. 21 19.12.34 20.28,00 " " Table 1(a) - G867B Date Time of Observation Flares Comment (U.T.) If-Io/Io Begin End Time of 3sigma/Io Integ- Colour General Peak ration 1977 Sept.10 21.20.52 21.25.32 0.271 0.038 2s U only 21.35.16 0.348 0.037 " " 21.44.52 *0.332 0.038 " " *Between 21.46.38 *0.346 0.038 " " 21h43m and 21.49.48 *0.533 0.038 " " 22h50m, 21.59.12 *0.648 0.038 " " there was 22.09.09 *0.305 0.038 " " a general 22.12.23 *0.515 0.038 " " rise in the 22.19.07 *0.372 0.038 " " star's 23.25.04 0.668 0.058 " " brightness 23.36.00 0.285 0.058 " " of 20%. Am- Sept.11 00.45.07 00.06.29 0.264 0.058 " " plitudes of 21.17.52 22.22.24 21.29.06 0.427 0.132 " " these flares 21.34.40 0.213 0.132 " " are referred 21.44.44 0.626 0.281 " " to the qui- 22.01.48 0.340 0.234 " " escent part 22.17.24 0.497 0.181 " " of the light 22.24.36 23.06.46 22.45.30 0.219 0.130 " " curve. 23.08.26 23.39.36 23.26.58 0.351 0.102 " " 23.45.37 23.59.41 0.218 0.194 " " Sept.12 00.45.08 00.23.23 0.451 0.152 " " Table 2 - G867A Date Time Sec z DeltaV' Delta(B'-V') Delta(U'-B') (U.T.) 25.10.1977 20:49 1.106 1.170 +1.947 +1.148 26.10.1977 20:14 1.052 1.059 +1.920 +1.030 18.11.1977 19:09 1.115 1.063 +1.916 +1.024 19.11.1977 18:30 1.061 1.085 +1.950 +1.087