论文标题
HR 1614移动组不是溶解的群集
The HR 1614 moving group is not a dissolving cluster
论文作者
论文摘要
速度空间中的HR 1614过度密度，很长一段时间以来被称为旧的（〜2 Gyr）和富含金属的（[Fe/H] 〜0.2）附近的移动组，其具有溶解的群集起源。太阳附近的这种古老和金属富含的群体的存在是非常出乎意料的，因为已知附近的绝大多数移动群体年轻。根据新的和明显更大的数据集，我们旨在重新投资HR 1614移动组的属性和来源。 为了识别和表征HR 1614移动组，我们使用GAIA DR2的星体数据；距离星空代码的距离，灭绝和红色更正； Galah和Apogee光谱调查的元素丰度； Skymapper调查中的光度金属度。估计Skymapper恒星的贝叶斯年龄。由于赫拉克勒斯流是距HR 1614移动组最接近速度空间的运动结构，因此我们将其用于比较。根据它们的太空速度选择了可能是两组成员的恒星。 HR 1614移动组主要位于负U速度，在U-V空间中不会形成恒定能量的拱门，并且在V中倾斜。过度密度不是化学均匀的，而是其恒星都存在于多种金属，年龄和元素丰度率的广泛范围。它们基本类似于在银河系薄和厚的磁盘中观察到的，即金属富含金属（-0.2 <[fe/h] <0.4）和alpha-poor的年轻人群（〜3 Gyr）。因此，不应将其视为解散的开放群集或增生人群。我们建议HR 1614具有复杂的起源，可以通过结合几种不同的机制来解释，例如与银河条和螺旋结构的共振，溶解螺旋结构的相相结合以及由于外部扰动而引起的相结合。
The HR 1614 overdensity in velocity space and has for a long time been known as an old (~2 Gyr) and metal-rich ([Fe/H]~0.2) nearby moving group that has a dissolving cluster origin. The existence of such old and metal-rich groups in the solar vicinity is quite unexpected since the vast majority of nearby moving groups are known to be young. In the light of new and significantly larger data sets we aim to re-investigate the properties and origin of the HR 1614 moving group. To identify and characterise the HR 1614 moving group we use astrometric data from Gaia DR2; distances, extinction, and reddening corrections from the StarHorse code; elemental abundances from the GALAH and APOGEE spectroscopic surveys; and photometric metallicities from the SkyMapper survey. Bayesian ages were estimated for the SkyMapper stars. Since the Hercules stream is the closest kinematical structure to the HR 1614 moving group in velocity space, we use it for comparison purposes. Stars that are likely to be members of the two groups were selected based on their space velocities. The HR 1614 moving group is located mainly at negative U velocities, does not form an arch of constant energy in the U-V space and is tilted in V. The overdensity is not chemically homogeneous but that its stars exist at a wide range of both metallicities, ages, and elemental abundance ratios. They are essentially similar to what is observed in the Galactic thin and thick disks, a younger population (~3 Gyr) that is metal-rich (-0.2<[Fe/H]<0.4) and alpha-poor. It should therefore not be considered as a dissolving open cluster, or an accreted population. We suggest that HR 1614 has a complex origin that could be explained by combining several different mechanisms such as resonances with the Galactic bar and spiral structure, phase-mixing of dissolving spiral structure, and phase-mixing due to an external perturbation.
