COMMISSION 27 OF THE I. A. U.
	 INFORMATION BULLETIN ON VARIABLE STARS
		     Number 2643

			          Konkoly Observatory
			          Budapest
			          13 December 1984

			          HU ISSN 0374 - 0676

      VARIATIONS IN THE SHELL SPECTRUM OF THE Be STAR EW Lac


 We observed EW Lac with the grating spectrograph attached to the 60/90-cm
Schmidt telescope of Beijing Observatory, giving dispersions of 50 A/mm and
86 A/mm. 22 spectrograms of this star were obtained from Sept., 1982 to Sept.,
1984.
 We found that the hydrogen shell lines on four spectrograms taken on Dec.
16, 18, 26, 1983 and Sept. 10, 1984, showed considerable variations. While the
hydrogen shell lines were with single cores on December 16, 1983, these lines
displayed double absorption cores on December 18, 1983, with the two components
of nearly equal intensity. On a spectrogram taken on December 26, 1983, this
phenomenon weakened considerably but was still apparent in H6-H10, and at the
same time the R components became obviously weaker than the V components. On a
plate taken on Sept. 10, 1984, these lines showed again sharper and deeper single
cores as on Dec. 16, 1983 (see Fig. 1.).

                            [FIGURE 1]

A portion of the density tracing of Balmer lines in four spectra of EW Lac

				      Table I
		    Shell line velocities of EW Lac in km/sec.
-------------------------------------------------------------------------------
Plate	  Date	   H5	    H6	    H7	    H8	  H9	   H10	  H11	   H12
No.	  1983
-------------------------------------------------------------------------------
SA 1333   Dec.16   -17.0   -12.0   -12.1    -4.2  -12.8   -20.2  -18.6	  -10.2
SA 1334   1983 V  -155.5  -166.0  -166.9  -159.4 -171.3  -159.3 -204.6	 -167.8
	  Dec.18R - 23.2  - 20.0  - 21.3  - 10.3 - 18.6  - 15.4 - 50.2	 - 11.5
SA 1371   1983 V   /	  -108.5  -108.9  -112.3 -109.4  - 99.6 -108.8	 - 89.6
	  Dec.26R + 14.1  +  5.4  + 17.9  +  7.3    1.1  + 15.1 -  1.4	    /
SA 1427   1984	  + 7.6   - 17.9  - 21.6  - 19.0  - 4.4  - 17.8 - 29.5   - 23.1
	  Sept.10
-------------------------------------------------------------------------------

We also measured the radial velocity of the shell lines H5-H12. The mean error
in the velocity values is +- 3.9 km/sec. The results are listed in Table I.
Our R component radial velocities are in agreement with the values of other
authors derived from single cores. The V component radial velocities showed
much larger variations than those of the R components from December 
18-26, 1983.





			 GUO YU-LIAN and CAO HUI-LAI
			 Peking Astronomical Observatory
			 Akademia Sinica
			 Peking, China