COMMISSION 27 OF THE I. A. U.
         INFORMATION BULLETIN ON VARIABLE STARS
                      Number 903

                                     Konkoly Observatory
                                     Budapest
                                     1974 June 29


             THE SECONDARY PERIOD OF AE UMa

    The variability of AE UMa = BV 92 was discovered on Bamberg
plates some twenty years ago (E. Geyer, R. Kippenhahn and W. Strohmeier, 
Kleine Veroff. Bamberg No 11, 1955). According to E. K.
Kharadze (Abastumani Bull. 10. 125, 1949) the star's spectral type
is A2, while W. Gotz and W. Wenzel (MVS No 571, 1961) classify it
as A9.

    V. P. Tsesevich (Astr. Circ. No 170, 1956) and G. S. Filatov (Astr.
Circ. No 215, 1960) observed the star visually, but the type of
variability could not be determined with certainty. Recent 
investigations by Tsesevich (Astr. Circ. No 775, 1973) have, however,
shown that the star belongs to the class of dwarf cepheids and has
a period of 0.086017055d. Tsesevich also called the attention to
the light curve variation of the variable.

   In order to determine the secondary period of AE UMa more
than one thousand photoelectric blue and yellow observations were
collected with the 20 in. Cassegrain and 24 in. Newton telescopes
of the Konkoly Observatory from January 15, 1974 till April 23,
1974. BD+44deg1882 was used as comparison star whose constancy was
checked by BD+44deg1881.

   The time of the 18 maxima observed are listed in the Table.
The brightnesses of the maxima in blue (b) and yellow (y) light
relative to the comparison star are also given.

   First the period of modulation P_m was derived from the heights
of the observed blue maxima (see upper part of the Figure) as P_m
0d.29364. Utilizing the maxima at nearly the same phase of modulation 
the main period P_0 was redetermined: P_0 = 0d.086017. This
value agrees remarkably well with Tsesevich's period.
The O - C values were calculated by the new elements:

   C_0(mean max.) = 2442062.5820 + 0d.086017 . E and
   C_m(min.ampl.) = 2442062.5960 + 0d.29364 . N

In the Figure Delta(b_max) and O - C_0 are plotted against the phase of
modulation psi = (O - C_m) / P_m.


                               Table

J.D. max     Delta(y_max)  Delta(b_max)    O - C    O - C_m    E    N

2442062.5835   +0.90           +0.77      +0.0015  +0.2811      0   -  1
    095.5293     .85             .69      +0.0028  +0.0456   +383   +112
       .6118     .69             .51      -0.0007  +0.1281    384    112
    106.4520     .73             .54      +0.0013  +0.1036    510    149
    119.5258:    .83:            .69:     +0.0003: +0.2573    662    193
    121.5017:    .70:            .52:     -0.0019: +0.1777    685    200
    128.2968     .81             .63      -0.0022  +0.2191    764    223
       .3872     .91             .76      +0.0022  +0.0158    765    224
       .4727     .77             .58      +0.0017  +0.1013    766    224
       .5550:    .74:            .57:     -0.0020: +0.1836    767    224
    133.4622     .73             .58      +0.0022  +0.0990    824    241
       .5440     .69             .54      -0.0020  +0.1808    825    241
    134.4055:    .70:            .53:     -0.0007: +0.1613    835    244
    147.3935:    .79:            .66:     -0.0013: +0.2292    986    288
    148.4295     .73             .60      +0.0025  +0.0906    998    292
       .5096     .69             .54      -0.0034  +0.1707    999    292
    159.4365     .78             .67      -0.0006  +0.2329   1126    329
    161.4145   +0.67           +0.50      -0.0010  +0.1555   1149    336


From P_0 and P_m we easily obtain the secondary period P_1 and the
period ratio P_1/P_0:

       P_1 = 0d.066529 and P_1/P_0 = 0.773

   It is worthy of note that exactly the same P_1/P_0 ratio was
obtained by Julia Balazs and L. Detre (Budapest Mitt. No 40, 1956)
for RV Ari which has only a slightly longer main period (0d.0931)
than AE UMa. It is also interesting that the phase relation 
between the D(b_max) - psi and (O - C_0) - psi curves is nearly the same for
both dwarf cepheids.

   In the next observational season the investigation of AE UMa
will be continued to determine its periods more accurately.



Konkoly Observatory,
Budapest
                                               B. SZEIDL



                       [FIGURE 1]