发表机构
Peking University; Kavli Institute for Astronomy and Astrophysics, Peking University; Purple Mountain Observatory, Chinese Academy of Sciences; University of Science and Technology of China; Tsung-Dao Lee Institute, Shanghai Jiao Tong University（北京大学; 北京大学科维理天文与天体物理研究所; 中国科学院紫金山天文台; 中国科学技术大学; 上海交通大学汤川路研究所）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究通过双组分星斑模型解释年轻星团NGC 2264中锂元素等效宽度的离散现象，发现星斑覆盖率差异可解释68%的观测离散度，减少了对非标准锂消耗机制的需求。
AI 中文摘要
年龄为数百万年的星团中，锂元素等效宽度存在先前无法解释的离散现象。本研究表明，年轻星团NGC 2264中大部分锂元素离散度可归因于观测到的星斑存在。我们利用15颗弱线金牛座T型星（WTTSs）的多历元高分辨率ESPaDOnS光谱和测光数据，证明了Li I 6708埃的等效宽度随观测到的星斑覆盖率而变化。为量化星斑的贡献，我们构建了一个经验性的双组分星斑模型。当考虑可见星斑覆盖率的差异时，68%的WTTSs落在模型预测的EW(Li)离散范围内，该范围对应0-90%的可见星斑覆盖率。我们发现NGC 2264中年龄离散度或重力与Li I等效宽度之间无相关性。我们的结果表明，引入星斑可以解释NGC 2264中大部分表观锂元素离散度，并减少但并未完全消除在此类年轻年龄下需要引入旋转驱动的锂消耗或其他非标准解释的需求。未来对年轻恒星中锂和铍的同时测量可能为这一情景提供独立的检验。
英文摘要
Star clusters with ages of a few Myr have a previously unexplained dispersion in the lithium equivalent widths. In this work, we show that much of the lithium spread of the young cluster NGC 2264 can be attributed to the observational presence of starspots. We demonstrate that the equivalent width of Li I 6708 Angstrom changes with observed spot coverage, using a sample of 15 Weak-Lined T Tauri Stars (WTTSs) with multi-epoch high-resolution ESPaDOnS spectra and photometry. To quantify the contribution of starspots, we construct an empirical two-component starspot model. When differences in visible spot coverage are taken into account, 68% of the WTTSs fall within the model-predicted EW(Li) dispersion for a range from 0-90% visible spot coverage. We find no correlation between the age spread or gravity and Li I equivalent width in NGC 2264. Our results suggest that invoking starspots can explain much of the apparent lithium spread in NGC 2264 and reduces but does not fully eliminate the need to invoke rotation-driven lithium depletion or other non-standard explanations at such young ages. Future simultaneous measurements of lithium and beryllium in young stars may provide an independent test of this scenario.
CommentsAccepted for publication in The Astrophysical Journal
