COMMUNICATIONS / MITTEILUNGEN
Perioden- und Lichtkurvenänderungen von AR Herculis
No. 51
Budapest, 1961
Abstract
The changes in the period and light curve of the cluster-type variable AR Her
have been investigated making use of all visual and photographic observations
published previously, and also of 3511 photographic and 1141 photoelectric
observations made recently in our observatory. The O-C diagrams for the
fundamental period and for the beat-period are shown. The validity of all
assumptions concerning relations between the variation of characteristic
quantities of the O-C curves is discussed and the existence of a third period
in the light variation indicated.
On the basis of all new photographic observations a mean light-surface
for the years 1955-57 has been constructed and compared with the light-surface
- being based upon photographic observations made under exactly similar
circumstances 18 years earlier. An important conclusion is the stability
of the shape of the curve describing the simultaneous changes in brightness
and phase of the maxima during one beat-period. The results were supported
by the light-surfaces as the superposition of two anharmonic oscillations
proved to be unsuccessful just as the application of other methods; some
results having been obtained with the aid of the harmonic analysis of the
light-surfaces.
After reducing our photoelectric observations to the B, V system, certain
regularity has been found in the variation of the color index. A final comment
deals with the significance of the results obtained in relation to the
theory of RR Lyrae stars.
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