AI 中文总结
研究通过韦布空间望远镜观测大麦哲伦星系边缘，利用颜色 - 星等图推导质量函数，明确未分辨双星贡献，测量不同质量比系统的双星比例，推导特定质量区间MF并拟合幂律，发现双星形成效率和低质量MF形状对环境依赖弱。
AI 中文摘要
大麦哲伦星系（LMC）等邻近星系是检验不同物理条件下初始质量函数的理想实验室，但以往研究受光度深度限制，对低质量区域约束不足。本文分析了韦布空间望远镜对LMC边缘靠近中等年龄大质量星团NGC 1846区域的超深观测数据。利用特定颜色 - 星等图推导出低至前所未有的质量（$M = 0.17 M_{\odot}$）的质量函数（MF），明确考虑了未分辨双星的贡献。对于质量比$q > 0.6$的系统，测量出双星比例$f_{\rm bin}^{q>0.6}=0.15\pm0.01$。还推导了0.17 - 0.82 $M_{\odot}$质量区间的MF并拟合幂律，得到斜率$\alpha = -1.49 \pm 0.16$。结果表明双星形成效率和低质量MF形状对环境依赖较弱。
英文摘要
Nearby galaxies such as the Large Magellanic Cloud (LMC) offer an ideal laboratory to test the initial mass function under different physical conditions, but previous works have been limited by photometric depth and have therefore poorly constrained the low-mass regime. Here, we analyze ultra-deep James Webb Space Telescope observations of a field in the LMC outskirts, near the intermediate-age and massive star cluster NGC 1846. Using the $m_{\rm F322W2}$ versus $m_{\rm F115W}-m_{\rm F322W2}$ color-magnitude diagram, we derive the mass function (MF) down to unprecedentedly low masses ($M=0.17 M_{\odot}$), explicitly accounting for the contribution of unresolved binaries, whose fraction is constrained directly from the data. For systems with mass ratios $q>0.6$, we measure a binary fraction of $f_{\rm bin}^{q>0.6}=0.15\pm0.01$, implying a total binary fraction of $f_{\rm bin}^{\rm TOT}=0.34\pm0.02$ for a flat mass-ratio distribution. This is consistent with values in the Small Magellanic Cloud (SMC) and in the Milky Way field, suggesting similar binary formation efficiency across low-density environments. We also derive the MF over the mass interval 0.17-0.82 $M_{\odot}$ and fit it with a power law, obtaining a slope of $α= -1.49 \pm 0.16$. This slope is shallower than the canonical Salpeter value ($α=-2.35$) and slightly shallower than that measured in the SMC field, while remaining consistent with determinations for Galactic open clusters and for several clusters in the Magellanic Clouds and the Milky Way. Together, these results support a scenario in which both binary formation efficiency and the shape of the low-mass MF depend only weakly on the environment.
Comments10 pages, 8 figures, accepted for publication in A&A
