COMMISSIONS 27 AND 42 OF THE IAU
             INFORMATION BULLETIN ON VARIABLE STARS
                         Number 3947

                                              Konkoly Observatory
                                              Budapest
                                              26 October 1993

                                              HU ISSN 0374 - 0676


                    EF DRACONIS IS A TRIPLE SYSTEM



 EF Draconis (1E1806.1+6944) was discovered serendipitously as an X-ray source in the
Einstein Observatory Extended Medium Sensitivity Survey (Gioia et al. 1987). Fleming
et al. (1989) made three radial-velocity measurements of the object and suggested that
the object is probably a W UMa-type variable. Shortly after Fleming et al.'s work, Robb
& Scarfe (1989) published their VRI light curves of the variable and confirmed that it is
a W UMa system. In 1989, Plewa et al. (1991) independently observed the system and
analysed their data. They concluded that EF Dra is an A-subtype of W UMa binaries,
with a mass ratio of 0.125. Wunder & Agerer (1992) also made B & V 
photometry of the variable and refined its orbital period.

                             [FIGURE 1]

         Figure 1.  Broadening function profiles of EF Dra. 
The letters P, S, and T indicate the profiles of the primary, secondary,
          and third components of the system, respectively.

  I observed the variable spectroscopically in 1991 and 1992 using the Cassegrain 
spectrograph and CCD detector on the 1.9-m telescope at David Dunlap Observatory. A total
of 43 spectra was obtained. The data were reduced for radial velocities by means of the
Spectral Broadening Function Method (Rucinski, 1992). It is interesting to discover that
this variable is actually a triple system. Two broadening function profiles obtained at
the two quadratures are shown in Fig. 1, in which P, S, and T indicate the profiles of
the primary, secondary, and third components of the system, respectively. The light of
the third component clearly revealed as a narrow component in the broadening function
profiles and must be included as "third light" in the light curve solution. A spectroscopic
orbit has been determined for the close pair, whose mass ratio was found to be small but
significantly different from the one derived by Plewa, et al. The close pair indeed belongs
to the A-subtype of W UMa stars. The velocity of the third component was constant
during the two periods of observations. It has a value of -38 km/sec comparative to the
systemic velocity of -42 km/sec of the contact binary in the triplet, which suggests that
the third component is physically related to the contact binary. A combined analysis of
the radial-velocity and existing light curves is in progress and will be published in the
near future.


                          WENXIAN LU^1
                          Department of Physics & Astronomy
                          Valparaiso University
                          Valparaiso, IN 46383, U.S.A.
                          E-mail: wlu@kepler.valpo.edu



References:

Fleming, T.A., Gioia, I.M., Maccacaro, T., 1989, AJ, 98, 692 [BIBCODE 1989AJ.....98..692F ]
Gioia, I.M., Maccacaro, T., Wolter, A. 1987, in IAU Symposium 124, Observational
   Cosmology, eds. A. Hewitt, G. Burbidge, Li-Zhi Fang (Reidel:Dordrecht), p.593 [BIBCODE 1987IAUS..124..593G ]
Plewa, T., Haber, G., Wlodarczyk, K.J., Krzesinski, J., 1991, Acta Astron., 41, 291 [BIBCODE 1991AcA....41..291P ]           
Robb, R.M., Scarfe, C.D., 1989, IBVS, No. 3370
Rucinski, S.M., 1992, AJ, 104, 1968 [BIBCODE 1992AJ....104.1968R ]
Wunder, E., Agerer, F., 1992, IBVS, No. 3811





 1 On leave from Shanghai Observatory, Academia Sinica