论文标题
银河球状簇中四个行星星云的适当运动成员测试
Proper-Motion Membership Tests for Four Planetary Nebulae in Galactic Globular Clusters
论文作者
论文摘要
四个行星星云（PNE）被认为是可能的或可能的银河球状簇（GC）成员。 These are Ps 1 = K648 in M15, GJJC 1 = IRAS 18333-2357 in M22, JaFu 1 in Palomar 6, and JaFu 2 in NGC 6441. In addition to lying close to the host GCs on the sky, these PNe have radial velocities that are consistent, within the errors and stellar velocity dispersions, with cluster membership.其余的成员资格标准是，中央恒星的适当动作（PMS）是否与宿主群集的适当动作（PMS）一致。我们已经对所有四个PNE进行了PM测试。两个中央恒星 - 最近在Gaia数据版本2（DR2）中列出的PS 1和GJJC 1-伴随的PMS的恒星。我们使用档案哈勃太空望远镜（HST）框架将PS 1 Central Star的PM更新为更精确的值。这两个PM在统计上与集群成员资格一致。对于其他两个PNE，我们使用档案HST图像来得出其核的PMS。对于JAFU 2，在几个时期有HST图像，而测得的核PM与宿主簇的PM非常吻合。对于JAFU 1，可用的档案HST图像不太最佳，结果的结论较低。中央恒星测量的PM与群集成员略有一致，但是对于更强大的会员测试来说，需要其他天文观测值。
Four planetary nebulae (PNe) are considered to be probable or possible members of Galactic globular clusters (GCs). These are Ps 1 = K648 in M15, GJJC 1 = IRAS 18333-2357 in M22, JaFu 1 in Palomar 6, and JaFu 2 in NGC 6441. In addition to lying close to the host GCs on the sky, these PNe have radial velocities that are consistent, within the errors and stellar velocity dispersions, with cluster membership. The remaining membership criterion is whether the proper motions (PMs) of the central stars are in agreement with those of the host clusters. We have carried out the PM test for all four PNe. Two of the central stars--those of Ps 1 and GJJC 1--have PMs listed in the recent Gaia Data Release 2 (DR2). We updated the PM of the Ps 1 central star to a more precise value using archival Hubble Space Telescope (HST) frames. Both PMs are statistically consistent with cluster membership. For the other two PNe, we used archival HST images to derive the PMs of their nuclei. For JaFu 2, there are HST images at several epochs, and the measured PM of the nucleus is in excellent agreement with that of the host cluster. For JaFu 1 the available archival HST images are less optimal and the results are less conclusive; the measured PM for the central star is marginally consistent with cluster membership, but additional astrometric observations are desirable for a more robust membership test.
