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arXiv · 2609.05825

A Uniform Census of Variable Stars in M101 Based on HST/ACS Photometry

Jiyu Wang·Xiaodian Chen·Pinjian Chen·Jianxing Zhang·Shu Wang·Licai Deng
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Abstract

We present a homogeneous HST/ACS F555W/F814W time-series census of variable stars in two M101 disk fields, using a uniform multi-band reduction and reproducible variable-selection workflow for nearby SN-host galaxies. Supplementary archival F555W epochs are used only to refine selected long-period solutions. Candidates are selected with Lomb-Scargle period searches, Fourier light-curve modeling, two-band consistency statistics, artificial-star-test photometric corrections, and mode-aware Cepheid refinement. The final catalog contains 1417 variable-star candidates, including 1102 secure fundamental-mode and 78 secure first-overtone classical Cepheids. Of these secure Cepheids, 420 are newly identified relative to the Shappee & Stanek catalog. The catalog also contains luminous candidates outside the classical Cepheid locus. We release the catalog and source-level two-band light curves for studies of Cepheid physics, stellar variability, and distance-scale applications.

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Jiyu Wang, Xiaodian Chen, Pinjian Chen, Jianxing Zhang, Shu Wang, Licai Deng. 2026-09-05. A Uniform Census of Variable Stars in M101 Based on HST/ACS Photometry. https://arxiv.org/abs/2609.05825

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