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名稱Title
2021天文年會
國立嘉義大學蘭潭校區
5月21日至23日

論文摘要

The Red Clump, Blue Clump, and the Binary Fraction of the Galactic Star Cluster M67

[ Poster ]

Erh-Shiang Yeh

M67 (NGC 2682) is a solar age (~4~6 Gyr) protruding open cluster stepping over 30' in the sky, with more than 500 known members, at a heliocentric distance of 800 to 900 pc, with solar age (~4~6 Gyr). Here we present characterization of M67 on the basis of the Gaia EDR3 data. With an iterative selection of reliable stellar members, we derived more accurate the angular size, distance and age than in the literature. Furthermore, we also try to distinguish white dwarf in M67 to rebuild the history of M67. The cluster has a marked red clump, the "crossroad" of the giant branch, horizontal branch, and asymptotic giant branch, which has been traditionally used as a distance ladder for galaxies. In addition, we notice a "blue clump", a kink near the main-sequence turn-off as a result of stellar evolution, which exists only for clusters within a certain age range. We discuss how this feature can be used to constrain the distance, age, and reddening of a cluster. The member list also allows us to compute the binary fraction as a function of stellar mass and of cluster radius.