Lithium in Wide Binaries: Effective Temperature Governs Depletion while Rotation Plays a Minor Role
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| Format: | Preprint |
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2026
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| author | Xie, Cheng-Cheng Tian, Hai-Jun Shi, Jian-Rong Zhou, Ze-Ming |
| author_facet | Xie, Cheng-Cheng Tian, Hai-Jun Shi, Jian-Rong Zhou, Ze-Ming |
| contents | Using a sample of 116 wide binary systems as coeval and chemically homogeneous stellar pairs, we investigate the factors governing lithium depletion in main-sequence stars. We recover the well-established morphology of the lithium--effective temperature ($T_{\mathrm{eff}}$) relation, including the Li dip (6200--6600\,K), the Li plateau (6000--6200\,K), and a linear trend for cooler stars ($T_{\mathrm{eff}}$ $<$ 6000\,K), where lithium abundance increases by $\sim$0.15\,dex per 100\,K. We demonstrate that the apparent correlation between projected rotational velocity ($v\sin i$) and lithium abundance is secondary to the underlying $T_{\mathrm{eff}}$ dependence; $v\sin i$ is not an independent driver of lithium depletion in our sample. Notably, we identify an anomalous system within the Li dip where the primary star exhibits a $\sim$1.4\,dex lithium excess compared to its secondary companion at nearly identical $T_{\mathrm{eff}}$. We discuss two plausible origins for this anomaly: external enrichment via planetesimal accretion or planetary engulfment, and binary interactions with an unresolved tertiary companion. Our results confirm $T_{\mathrm{eff}}$ as the dominant parameter controlling lithium depletion, while highlighting that additional, non-standard processes can occasionally produce significant lithium enrichment. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2603_18603 |
| institution | arXiv |
| publishDate | 2026 |
| record_format | arxiv |
| spellingShingle | Lithium in Wide Binaries: Effective Temperature Governs Depletion while Rotation Plays a Minor Role Xie, Cheng-Cheng Tian, Hai-Jun Shi, Jian-Rong Zhou, Ze-Ming Solar and Stellar Astrophysics Using a sample of 116 wide binary systems as coeval and chemically homogeneous stellar pairs, we investigate the factors governing lithium depletion in main-sequence stars. We recover the well-established morphology of the lithium--effective temperature ($T_{\mathrm{eff}}$) relation, including the Li dip (6200--6600\,K), the Li plateau (6000--6200\,K), and a linear trend for cooler stars ($T_{\mathrm{eff}}$ $<$ 6000\,K), where lithium abundance increases by $\sim$0.15\,dex per 100\,K. We demonstrate that the apparent correlation between projected rotational velocity ($v\sin i$) and lithium abundance is secondary to the underlying $T_{\mathrm{eff}}$ dependence; $v\sin i$ is not an independent driver of lithium depletion in our sample. Notably, we identify an anomalous system within the Li dip where the primary star exhibits a $\sim$1.4\,dex lithium excess compared to its secondary companion at nearly identical $T_{\mathrm{eff}}$. We discuss two plausible origins for this anomaly: external enrichment via planetesimal accretion or planetary engulfment, and binary interactions with an unresolved tertiary companion. Our results confirm $T_{\mathrm{eff}}$ as the dominant parameter controlling lithium depletion, while highlighting that additional, non-standard processes can occasionally produce significant lithium enrichment. |
| title | Lithium in Wide Binaries: Effective Temperature Governs Depletion while Rotation Plays a Minor Role |
| topic | Solar and Stellar Astrophysics |
| url | https://arxiv.org/abs/2603.18603 |