COMMISSION 27 OF THE I. A. U.
         INFORMATION BULLETIN ON VARIABLE STARS
                     Number 2152

                                 Konkoly Observatory
                                 Budapest
                                 1982 May 28

                                 HU ISSN 0374-0676


       PHOTOELECTRIC OBSERVATIONS OF 20 Leo (HR 3889)



 20 Leo is a spectroscopic - visual triple system in which a component
is a delta Scuti variable star; the photometric variability was discovered
by Danziger and Dickens (1967) and Elliott (1974). Fekel and Bopp (1977)
have shown that component A is a spectroscopic binary (P = 4.15 d) consisting 
of two nearly equal, perhaps marginal Am stars, and the visual companion B 
(P ~ 200 y) is the delta Scuti star. The three stars have nearly like
mass, rotational velocity and evolutionary state.
 Elliott (1974) has found photometric variability with a period of about
0.082 d; he reports that little evidence was found for beats, and the
amplitude DeltaV of the light curve is ~ 0.02 mag.


                          Table I
  J.D.Hel.   DeltaV  sigma   n    J.D.Hel.     DeltaV  sigma  n

2445031.371   1.286   .002   4   2445031.484   1.292   .002   3
       .392   1.294   .001   6          .496   1.291   .004   6
       .403   1.284   .003   6          .507   1.291   .003   6
       .415   1.286   .003   5          .518   1.288   .004   5
       .426   1.290   .002   4          .528   1.291   .001   4
       .437   1.296   .002   5          .537   1.291   .005   6
       .449   1.296   .004   6          .548   1.300   .004   6
       .458   1.295   .001   4          .559   1.290   .006   6
       .466   1.294   .001   4          .570   1.285   .005   6
       .476   1.290   .002   6          .579   1.291   .006   4


 We have observed 20 Leo during the night of March 2, 1982 at the 102 cm
reflector of the Merate Observatory; we have used a standard V filter, a
Lallemand photomultiplier and a Weitbrecht-Gardiner amplifier. The comparison 
(CF) and the check (CK) stars were HD 84739 and 84497, respectively.
The results of the observations are reported in Table I and Figure 1. One
can see that the variability of 20 Leo is small during the whole observing
time; the amplitude is of order 0.01 mag and the curve does not seem to
be regular. If we compare our results to Elliott's ones, we can conclude
that there are amplitude changes and there exists probably more than one
pulsation mode.

                        [FIGURE 1]

 Since the delta Scuti component cannot be separated photometrically from
its companions, the intrinsic amplitude is larger than that observed. If
we use the DeltaV-L-P relation (Antonello et al., 1981) to predict the
intrinsic probable maximum amplitude, and, following Fekel and Bopp, assume
three equal luminosities for the three components, we obtain a probable
observed maximum amplitude DeltaV ~ 0.03 mag.



                     E. ANTONELLO, L. MANTEGAZZA
                     Osservatorio Astronomico di Brera
                     Via E. Bianchi 46, 22055 MERATE
                     ITALY



References:
Antonello, E., Fracassini, M. and Pastori, L.: 1981, Astrophys. Space Sci.
 78, 435. [BIBCODE 1981Ap&SS..78..435A ]
Danziger, I. and Dickens, R.: 1967, Astrophys. J. 149, 55. [BIBCODE 1967ApJ...149...55D ]
Elliott, J.: 1974, Astron. J. 79, 1082. [BIBCODE 1974AJ.....79.1082E ]
Fekel, F.C. and Bopp, B.W.: 1977, Publ. Astron. Soc. Pacific 89, 216. [BIBCODE 1977PASP...89..216F ]