Atmospheric Parameter Determination of RR Lyrae Stars With Mephisto Multi-band Photometry
Abstract
Phase-resolved atmospheric parameters of pulsating stars, including RR Lyrae stars and Cepheids, are essential for studying stellar structure and pulsation physics and for establishing accurate stellar benchmarks for Galactic structure and assembly history. We present a photometric framework that simultaneously infers Teff, log g, and [Fe/H] from Mephisto multi-epoch, multi-band (u, v, g, r, i, z) photometry. A supervised neural-network forward model is built by training on synthetic colors derived from theoretical stellar atmosphere models. It reproduces the synthetic colors to a precision of 0.01 per cent. The model is applied to observed multi-epoch colors to derive phase-dependent atmospheric parameters. We apply the method to six RRab and four RRc stars in three globular clusters observed with Mephisto. We find typical per-phase uncertainties of about 62 K in effective temperature (Teff), 0.10 dex in surface gravity (log g), and 0.16 dex in metallicity ([Fe/H]). Repeated measurements across the pulsation cycle reduce the typical formal uncertainty of the final [Fe/H] estimates to roughly 0.03 dex. A sensitivity analysis indicates that the five Mephisto colors provide distinct and complementary constraints on the three stellar atmospheric parameters: (u-v) provides robust constraints on log g, (v-g) is informative for estimating [Fe/H], and (u-v), (v-g), (g-r), (r-i), and (i-z) all provide information on Teff. The results demonstrate that Mephisto multi-epoch, multi-band photometry can deliver precise, cost-effective phase-resolved atmospheric parameters for RR Lyrae stars, offering an efficient way to construct large samples of stellar benchmarks for studies of stellar pulsation physics and Galactic structure and evolution.
Related
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BibTeX
@misc{zou2026atmospheric,
title = {{Atmospheric Parameter Determination of RR Lyrae Stars With Mephisto Multi-band Photometry}},
author = {Xingzhu Zou and Maosheng Xiang and Tanda Li and Lanya Mou and Haibo Yuan and Xinlei Chen and Yu Pan and Kaushik Chatterjee and Guowang Du and Yuan Fang and Helong Guo and Brajesh Kumar and Edoardo P. Lagioia and Chenxu Liu and Xiangkun Liu and Tao Wang and Yuan-Pei Yang and Jinghua Zhang and Shiyan Zhong and Xufeng Zhu and Xiaowei Liu},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.38601},
eprint = {2610.38601},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.38601},
}
RIS
TY - UNPB
TI - Atmospheric Parameter Determination of RR Lyrae Stars With Mephisto Multi-band Photometry
AU - Xingzhu Zou
AU - Maosheng Xiang
AU - Tanda Li
AU - Lanya Mou
AU - Haibo Yuan
AU - Xinlei Chen
AU - Yu Pan
AU - Kaushik Chatterjee
AU - Guowang Du
AU - Yuan Fang
AU - Helong Guo
AU - Brajesh Kumar
AU - Edoardo P. Lagioia
AU - Chenxu Liu
AU - Xiangkun Liu
AU - Tao Wang
AU - Yuan-Pei Yang
AU - Jinghua Zhang
AU - Shiyan Zhong
AU - Xufeng Zhu
AU - Xiaowei Liu
PY - 2026
DA - 2026/10/28
PB - arXiv
DO - 10.48550/arxiv.2610.38601
UR - https://arxiv.org/abs/2610.38601
AB - Phase-resolved atmospheric parameters of pulsating stars, including RR Lyrae stars and Cepheids, are essential for studying stellar structure and pulsation physics and for establishing accurate stellar benchmarks for Galactic structure and assembly history. We present a photometric framework that simultaneously infers Teff, log g, and [Fe/H] from Mephisto multi-epoch, multi-band (u, v, g, r, i, z) photometry. A supervised neural-network forward model is built by training on synthetic colors derived from theoretical stellar atmosphere models. It reproduces the synthetic colors to a precision of 0.01 per cent. The model is applied to observed multi-epoch colors to derive phase-dependent atmospheric parameters. We apply the method to six RRab and four RRc stars in three globular clusters observed with Mephisto. We find typical per-phase uncertainties of about 62 K in effective temperature (Teff), 0.10 dex in surface gravity (log g), and 0.16 dex in metallicity ([Fe/H]). Repeated measurements across the pulsation cycle reduce the typical formal uncertainty of the final [Fe/H] estimates to roughly 0.03 dex. A sensitivity analysis indicates that the five Mephisto colors provide distinct and complementary constraints on the three stellar atmospheric parameters: (u-v) provides robust constraints on log g, (v-g) is informative for estimating [Fe/H], and (u-v), (v-g), (g-r), (r-i), and (i-z) all provide information on Teff. The results demonstrate that Mephisto multi-epoch, multi-band photometry can deliver precise, cost-effective phase-resolved atmospheric parameters for RR Lyrae stars, offering an efficient way to construct large samples of stellar benchmarks for studies of stellar pulsation physics and Galactic structure and evolution.
ER -