Göttingen 2025 – scientific programme

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EP: Fachverband Extraterrestrische Physik

EP 10: Poster Session

EP 10.4: Poster

Thursday, April 3, 2025, 11:00–12:30, ZHG Foyer 1. OG

Stochastic High Frequencies in massive stars — •Julieta Paz Sanchez Arias¹, Suryani Guha^1,2, and Alejandra Christen³ — ¹Astronomical Institute, Czech Academy of Science, Fričova 298, 251 65 Ondřejov, Czech Republic. — ²Faculty of Mathematics and Physics, Charles University, Prague, Czech Republic. — ³Instituto de Estadistica, Universidad de Valparaiso, Valparaiso, Chile.

The light curves of massive OB stars are known to be affected by red noise, which translates into a power excess in the low-frequency range. The origin of these stochastic low frequencies has been proposed to be convection and/or granulation at the stellar surface, internal gravity waves stochastically excited, and inhomogeneities in the winds of massive stars. However, the underlying physics of their origin is still poorly understood. Thanks to a new mathematical method for frequency analysis (the Empirical Mode Decomposition method), we have found frequencies excited at high frequency ranges in massive stars, which seem to be connected also with a stochastic process. In this work, we present numerical experiments with ARFIMA processes to model stochastic high frequencies (SHF) signals and detailed frequency analysis of a group of massive stars observed with TESS mission that exhibit SHF. The presence of these newly detected SHF provides additional tools to understand the origin of the red noise in massive stars.

Keywords: Asteroseismology; Blue Supergiant stars; frequency analysis