标题： 通过其运动学揭示上天蝎座星协的恒星形成历史 显示英文标题

标题： Unveiling the star formation history of the Upper Scorpius association through its kinematics

摘要： 星协不仅在物理空间中，而且在速度空间中都可以被识别为源的过密度。 它们成员的共同运动逐渐被银河潮汐场侵蚀，部分地类似于初始的运动结构。 利用盖亚EDR3的最新数据，结合GALAH和APOGEE的径向速度，我们追溯了属于上天蝎座（天蝎-半人马座的一个子群）的恒星的当前位置。 该子群大约一半（“聚集”群体）似乎由许多较小的实体组成，这些实体在过去曾处于更紧密的配置中。 运动学双重性的存在反映在较年轻的聚集群体和较老的弥散群体之间的年龄扩散中，这进一步通过具有不同分数$f_D$的盘状恒星（$f_D = 0.24\pm0.02$与$f_D = 0.10\pm 0.01$）得到确认。 上天蝎座中的恒星形成似乎持续了超过10百万年，并以小群体的形式进行，这些群体在几百万年后在较老群体的场中解散，但会保留一段时间其初始结构的记忆。 在这方面，通过等时线和运动学推断出的年龄差异可能提供一种强大的工具来量化气体去除的时间尺度。 显示英文摘要

摘要： Stellar associations can be discerned as overdensities of sources not only in the physical space but also in the velocity space. The common motion of their members, gradually eroded by the galactic tidal field, is partially reminiscent of the initial kinematic structure. Using recent data from Gaia EDR3, combined with radial velocities from GALAH and APOGEE, we traced back the present positions of stars belonging to Upper Scorpius, a subgroup of Scorpius-Centaurus, the nearest OB association. About one half of the subgroup (the "clustered" population) appears composed of many smaller entities, which were in a more compact configuration in the past. The presence of a kinematic duality is reflected into an age spread between this younger clustered population and an older diffuse population, in turn confirmed by a different fraction $f_D$ of disc-bearing stars ($f_D = 0.24\pm0.02$ vs $f_D = 0.10\pm 0.01$). Star formation in Upper Scorpius appears to have lasted more than 10 Myr and proceeded in small groups that, after a few Myr, dissolve in the field of the older population but retain for some time memory of their initial structure. The difference of ages inferred through isochrones and kinematics, in this regard, could provide a powerful tool to quantify the timescale of gas removal.