DESI中银河系场星的双星比例：对化学丰度的依赖
The Binary Fraction of Milky Way Field Stars in DESI: Dependence on Chemical Abundance
- Shanghai Jiao Tong University（上海交通大学）
- University of Edinburgh（爱丁堡大学）
- University of Cambridge（剑桥大学）
机构由 AI 辅助整理，请以论文原文为准。
AI总结：
本研究利用DESI银河系巡天二期数据，通过多历元视线速度变化统计方法，发现银河系场主序转折星的双星比例主要随金属丰度降低而升高，其变化由化学丰度主导。
AI中文摘要：
双星群体编码了恒星形成的物理条件以及恒星群体后续演化的信息。我们采用一种基于多历元视线速度变化的统计方法，利用DESI银河系巡天二期数据，对银河系场主序转折星的双星比例$\mathit{f}_b$进行了约束。研究发现，$\mathit{f}_b$主要随[Fe/H]降低而升高；在[Fe/H] $\gtrsim -1.3$时，$\mathit{f}_b$随[Mg/Fe]升高呈适度增加趋势，而在更低的[Fe/H]下未检测到明显趋势。$\mathit{f}_b$随角动量和银道面高度的表观变化，很大程度上可由其 underlying 的[Fe/H]分布解释，剩余变化则大致遵循[Mg/Fe]的差异。在[Fe/H]-[Mg/Fe]平面的重叠区域内，薄盘、厚盘、恒星晕和GSE群体的双星比例无显著差异。因此，我们的测量表明，$\mathit{f}_b$的变化主要由化学丰度决定，这可由金属丰度依赖的气体冷却效率和碎裂机制解释；在固定[Fe/H]时，较弱的[Mg/Fe]依赖可能与恒星形成条件相关，高[Mg/Fe]恒星通常在气体更丰富、更湍流的环境中更早形成。
英文摘要：
Binary populations encode information about the physical conditions of star formation and the subsequent evolution of stellar populations. Adopting a statistical method based on multi-epoch line-of-sight velocity variations, we constrain the binary fraction, $f_b$, of field main-sequence turn-off stars in the Milky Way using data from the second data release of the DESI Milky Way Survey. $f_b$ is found to primarily increase with lower [Fe/H]. At $[\mathrm{Fe}/\mathrm{H}]\gtrsim -1.3$, $f_b$ shows a modest increase with increasing [Mg/Fe], whereas no clear trend is detected at lower [Fe/H]. The apparent variations of $f_b$ with angular momentum and Galactic height are largely explained by their underlying [Fe/H] distributions, while the remaining variations broadly follow differences in [Mg/Fe]. Within overlapping regions of the [Fe/H]--[Mg/Fe] plane, the thin disk, thick disk, stellar halo and GSE populations exhibit no significant differences in their binary fractions. Thus, our measurements indicate that the variation in $f_b$ is dominated by chemical abundance, which could be explained by the metallicity-dependent gas cooling efficiency and fragmentation. The weaker [Mg/Fe] dependence at fixed [Fe/H] might be associated with the formation conditions of stars, with higher [Mg/Fe] stars generally forming earlier under a more gas-rich and turbulent environment.
