论文标题
我们邻居的家庭图片：调查附近开放群集的质量功能和动态参数
The family pictures of our neighbours: investigating the mass function and dynamical parameters of nearby open clusters
论文作者
论文摘要
We determine the mass functions (MFs) and the dynamical parameters of 15 nearby open clusters (OCs) using the unprecedented data set of the Gaia Early Data Release 3. We select the members of each cluster by combining the photometric (colour and magnitude) and astrometric (parallax and proper motions) parameters of stars, minimizing the contamination from Galactic field interlopers.通过比较沿簇主序列的恒星的分布与最合适的合成种群的分布，我们发现了当今的MF和OC的二进制分数，以及它们的动态参数，例如质量，半质量半径和半质量的弛豫时间。我们发现，当今OC的全球MF与单个幂律函数（$ f（m）\ propto m^α$一致，斜率$ -3 <α<-0.6 $，包括二个sustolar，$ 0.2 <m/\ text {m} _ \ odot <1 $，以及超级质量质量制度。 MF斜率与年龄与半质量松弛时间的比率之间存在显着相关性，这与在银河球状簇中已经观察到的相同结论类似。但是，与球状簇相比，OC沿不同的轨道发展，可能表明其初始质量功能（IMF）的原始差异。与蒙特卡洛模拟的比较表明，所有分析的OCS都可以诞生，其中具有斜率$α_ {\ text {imf}} <-2.3 $的IMF。我们还表明，较少进化的OC的MF与太阳邻域的MF一致，表明OC的溶解与银河盘的形成之间可能存在联系。
We determine the mass functions (MFs) and the dynamical parameters of 15 nearby open clusters (OCs) using the unprecedented data set of the Gaia Early Data Release 3. We select the members of each cluster by combining the photometric (colour and magnitude) and astrometric (parallax and proper motions) parameters of stars, minimizing the contamination from Galactic field interlopers. By comparing the observed distribution of stars along the cluster main sequence with the best-fitting synthetic population, we find the present-day MF and the binary fraction of the OCs, along with their dynamical parameters like mass, half-mass radius, and half-mass relaxation time. We found that the global present-day MF of OCs are consistent with a single power-law function, $F(m)\propto m^α$, with slopes $-3<α<-0.6$ including both subsolar, $0.2<m/\text{M}_\odot<1$, and supersolar mass regimes. A significant correlation between the MF-slope and the ratio of age to half-mass relaxation time is evidenced, similarly to the same conclusion already observed among Galactic globular clusters. However, OCs evolve along different tracks in comparison with the globular clusters, possibly indicating primordial differences in their initial mass function (IMF). The comparison with Monte Carlo simulations suggests that all the analysed OCs could have been born with an IMF with slope $α_{\text{IMF}}<-2.3$. We also show that the less evolved OCs have a MF consistent with that of the solar neighbourhood, indicating a possible connection between the dissolution of OCs and the formation of the Galactic disc.
