Gergely Hajdu

Nicolaus Copernicus Astronomical Center, Polish Academy of Sciences

Session VI: Stars, star systems and interstellar matter

Thursday 14th September 2023 11:28 – 11:41

abstract:
We present the first detection of circumstellar matter around a sample of RR Lyrae stars, identified through their variable mean magnitudes in the OGLE survey, and confirmed by other data sets (MACHO, EROS-2, KMTNet). While other phenomena, such as blending with other sources, may lead to a similar change of the mean magnitudes of RR Lyrae stars, the unchanging light-curve shapes and amplitudes lead to an unambiguous separation between them and variable extinction from circumstellar matter. The extinction ratios calculated from multi-wavelength light curves possess a wide range, hinting at a similarly wide variety of dust properties. We discuss the prevalence, implications and possible formation mechanisms of circumstellar matter around RR Lyrae variables, with special attention to its connection to binarity.