标题： 使用MUSE观测到的年轻大质量SMC星团NGC 330。 恒星参数和自转速度 显示英文标题

标题： The young massive SMC cluster NGC 330 seen by MUSE III. Stellar parameters and rotational velocities

摘要： 恒星初始自转速率的起源，以及恒星表面自转速度如何通过内部角动量传输或与双星伴星相互作用而发生变化，在恒星天文学中仍然是悬而未决的问题。 在这里，我们旨在推导物理参数并研究年龄为35百万年的大麦哲伦云中NGC 330星团中B型和Be型恒星（投影）自转速度的分布。 NGC 330处于一个年龄范围，在该范围内，接近星团主序转折点的相互作用双星数量预计会很高。 我们开发了一种同时利用多波段哈勃太空望远镜测光数据和多单元光谱探测器光谱数据进行网格拟合的方法，以调整大气模型。 这使我们能够一致地约束超过250颗亮度大于mF814W = 18.8星等的B型和Be型恒星的物理参数。 NGC 330中的Be型恒星的自转速度显著高于B型恒星。 这些恒星的自转速度随颜色-绝对星等图中的位置变化，定性上符合双星群体合成的预测。 与更年轻的星团相比，NGC 330中的恒星平均旋转得更快。 NGC 330中35百万年老的恒星群体的自转速度定量上与经历显著双星相互作用的恒星群体的预测一致：大部分B型恒星可能是单星或在相互作用前的双星系统中的主要成员。 快速旋转的Be型恒星可能是先前相互作用中的质量和角动量增益者，而接近主序转折点的Be型恒星可能是被加速的单星。 主序转折点以上的缓慢旋转、看起来单星的恒星可能是合并产物。 从这个框架来看，NGC 330与其他年轻群体的不同v sin i特性可以得到理解。 显示英文摘要

摘要： The origin of initial rotation rates of stars, and how a star's surface rotational velocity changes during the evolution, either by internal angular momentum transport or due to interactions with a binary companion, remain open questions in stellar astrophysics. Here, we aim to derive the physical parameters and study the distribution of (projected) rotational velocities of B-type stars in the 35 Myr-old, massive cluster NGC 330 in the Small Magellanic Cloud. NGC 330 is in an age range where the number of post-interaction binaries is predicted to be high near the cluster turnoff (TO). We develop a simultaneous photometric and spectroscopic grid-fitting method adjusting atmosphere models on multi-band Hubble Space Telescope photometry and Multi Unit Spectroscopic Explorer spectroscopy. This allows us to homogeneously constrain the physical parameters of over 250 B and Be stars, brighter than mF814W = 18.8 mag. The rotational velocities of Be stars in NGC 330 are significantly higher than the ones of B stars. The rotational velocities vary as a function of the star's position in the color-magnitude diagram, qualitatively following predictions of binary population synthesis. A comparison to younger clusters shows that stars in NGC 330 rotate more rapidly on average. The rotational velocities of the 35 Myr old population in NGC 330 quantitatively agree with predictions for a stellar population that underwent significant binary interactions: the bulk of the B stars could be single stars or primaries in pre-interaction binaries. The rapidly spinning Be stars could be mass and angular momentum gainers in previous interactions, while those Be stars close to the TO may be spun-up single stars. The slowly rotating, apparently single stars above the TO could be merger products. The different vsini-characteristics of NGC 330 compared to younger populations can be understood in this framework.