Robin Petry & Simon Lars Hesse
As part of the advanced lab course at the Technical University of Darmstadt, the pulsation-variable star “V1139 Her“
was observed with the TURMX telescope system from 12 June 2024 at 23:00 to 13 June 2024 at 6:15 (CEST).
The aim of the experiment was to record a light curve of the pulsation-variable star. The light curve describes how the
brightness of the star changes over time. The brightness of most stars is approximately constant. A star that changes its
brightness periodically is rather rare and therefore an interesting object to observe. The brightness can be specified as a
comparison of radiation fluxes to a comparison star. The measured light curve and a curve fit can be seen in the figure below.
The measurement points are shown in blue with uncertainty bars and the curve fit is shown in yellow. The horizontal
time axis is shown in days, with the first measurement time point defined as 0 d. The brightness is given as the ratio
between the radiant flux of the variable star SV and the radiant flux of a comparison star SC . A Fourier series up to
truncation order 6 was used for the curve fitting.
With the help of the curve fitting, the period duration and the relative change in brightness or radiant flux could be
determined. The period duration was determined to be 98.48 ± 0.09 min. The relative change in brightness is 22.56 ±
0.34 %.
