Metal-Poor Stars as Metal-Rich Impostors via Planet Engulfment
Abstract
Planet engulfment leads to planetary mass accretion and angular momentum deposition into the stellar envelope. This study uses MESA models to investigate the long-term impact of engulfment on stellar metallicity and rotational velocity, as well as the effect of rotational mixing on metal enrichment. Our models show that engulfment occurring during the late main-sequence (MS) stage yields significantly higher surface enrichment than at the ZAMS. Rotational mixing generally suppresses enrichment; however, metal-poor stars can sustain super-solar abundances for several Gyr, whereas high-metallicity stars remain largely unaffected. Although engulfment causes an instantaneous spin-up, this angular momentum injection is transient, and the star quickly re-converges to its standard rotational evolution. Thus, MS spin-up cannot serve as a long-term observational indicator. Because convective envelope thickness and MS lifetime dictate the magnitude and duration of enrichment, identifying engulfment signatures requires balancing the long-lived but diluted signals in 0.7 M_sun stars against the strong yet short-lived enrichment in 1.2 M_sun stars. Consequently, 1.0 M_sun stars offering both substantial enrichment and a relatively long MS lifetime represent optimal targets for observational searches.
Related
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BibTeX
@misc{li2026metalpoor,
title = {{Metal-Poor Stars as Metal-Rich Impostors via Planet Engulfment}},
author = {Zongheng Li and Shi Jia and Jie Su and Shang-Fei Liu and Jianheng Guo},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.29174},
eprint = {2609.29174},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.29174},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Metal-Poor Stars as Metal-Rich Impostors via Planet Engulfment
AU - Zongheng Li
AU - Shi Jia
AU - Jie Su
AU - Shang-Fei Liu
AU - Jianheng Guo
PY - 2026
DA - 2026/09/26
PB - arXiv
DO - 10.48550/arxiv.2609.29174
UR - https://arxiv.org/abs/2609.29174
AB - Planet engulfment leads to planetary mass accretion and angular momentum deposition into the stellar envelope. This study uses MESA models to investigate the long-term impact of engulfment on stellar metallicity and rotational velocity, as well as the effect of rotational mixing on metal enrichment. Our models show that engulfment occurring during the late main-sequence (MS) stage yields significantly higher surface enrichment than at the ZAMS. Rotational mixing generally suppresses enrichment; however, metal-poor stars can sustain super-solar abundances for several Gyr, whereas high-metallicity stars remain largely unaffected. Although engulfment causes an instantaneous spin-up, this angular momentum injection is transient, and the star quickly re-converges to its standard rotational evolution. Thus, MS spin-up cannot serve as a long-term observational indicator. Because convective envelope thickness and MS lifetime dictate the magnitude and duration of enrichment, identifying engulfment signatures requires balancing the long-lived but diluted signals in 0.7 M_sun stars against the strong yet short-lived enrichment in 1.2 M_sun stars. Consequently, 1.0 M_sun stars offering both substantial enrichment and a relatively long MS lifetime represent optimal targets for observational searches.
ER -