Understanding the photometric variability of \theta Ori Aa

Understanding the photometric variability of ζ Ori Aa

B. Buysschaert, C. Neiner, T. Ramiaramanantsoa, N. D. Richardson, A. David-Uraz, A. F. J. Moffat and the BRITE Team

We studied the variability of the magnetic O-type supergiant ζ Ori Aa using multi- colour BRITE photometry. We confirmed the known rotation frequency frot=0.15±0.02 c/d, and detected some of its higher harmonics, of which 4f rot is compatible with the known DAC recurrence timescale. Thanks to simultaneous high-resolution CHIRON spectroscopy, we could identify another frequency fenv=0.10±0.02 c/d, caused by the circumstellar environment. Variations in the circumstellar environment are believed to cause the observed difference between the BRITE lightcurves.

Proceedings of the Polish Astronomical Society, vol. 5, 101-108 (2017)

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