X-ray properties of RR Lyrae and Cepheid variables from eROSITA

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Hauptverfasser: Ilkiewicz, Krystian, Netzel, Henryka
Format: Preprint
Veröffentlicht: 2025
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author Ilkiewicz, Krystian
Netzel, Henryka
author_facet Ilkiewicz, Krystian
Netzel, Henryka
contents We present a search for X-ray counterparts to RR Lyrae and Cepheid variables using data from the first eROSITA all-sky survey. We identify seven RR Lyrae and eight Cepheid variables with positional matches to X-ray sources. While most Cepheid associations appear reliable, the RR Lyrae matches are predominantly spurious. Only one source, OGLE-BLG-RRLYR-00252, appears to be a plausible RR Lyrae detection, potentially representing the first observational evidence of X-ray emission from a star of this type. Its inferred luminosity suggests that RR Lyrae stars are intrinsically at least two orders of magnitude fainter in X-rays than the brightest Cepheids. We also observe a tentative increase in X-ray luminosity with pulsation period among classical Cepheids, and higher luminosities in type II Cepheids at comparable periods. These trends may reflect intrinsic differences in atmospheric structure and shock efficiency, offering new insight into the mechanisms driving high-energy emission in pulsating stars.
format Preprint
id arxiv_https___arxiv_org_abs_2512_12290
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle X-ray properties of RR Lyrae and Cepheid variables from eROSITA
Ilkiewicz, Krystian
Netzel, Henryka
Solar and Stellar Astrophysics
We present a search for X-ray counterparts to RR Lyrae and Cepheid variables using data from the first eROSITA all-sky survey. We identify seven RR Lyrae and eight Cepheid variables with positional matches to X-ray sources. While most Cepheid associations appear reliable, the RR Lyrae matches are predominantly spurious. Only one source, OGLE-BLG-RRLYR-00252, appears to be a plausible RR Lyrae detection, potentially representing the first observational evidence of X-ray emission from a star of this type. Its inferred luminosity suggests that RR Lyrae stars are intrinsically at least two orders of magnitude fainter in X-rays than the brightest Cepheids. We also observe a tentative increase in X-ray luminosity with pulsation period among classical Cepheids, and higher luminosities in type II Cepheids at comparable periods. These trends may reflect intrinsic differences in atmospheric structure and shock efficiency, offering new insight into the mechanisms driving high-energy emission in pulsating stars.
title X-ray properties of RR Lyrae and Cepheid variables from eROSITA
topic Solar and Stellar Astrophysics
url https://arxiv.org/abs/2512.12290