A Cluster Where Local Gas in the Milky Way is Mixing with Circumgalactic Gas and Forms Stars with a Wide Range of Abundances

The Milky Way promotes the formation of young stellar objects (YSOs) by accreting nearby metal-poor gas. The degree of mixing varies, resulting in different metallicity of the stars. We found a pre-main-sequence star cluster at R.A. ∼54 . ° 0, decl. ∼31 . ° 7, rad ∼3 . ° 9, where APOGEE shows that the metallicity of the stars ranges from [Fe/H] ∼ −1 dex, [ α /M] ∼−0.3 dex, which should be close to the abundances of the accreted gas, to [Fe/H] ∼ 0.3 dex, [ α /M] ∼ 0.1 dex, the abundances of the Milky Way’s local gas, arranged in a straight line. In the EBHIS H I survey data, there is a accretion gas stream located near local standard of rest velocity −46.3 km s −1 , a gas cavity produced during star formation near −3.8 km s −1 , and a local gas structure near 6.5 km s −1 . Our target cluster is composed of two subclusters, and the accretion gas stream happens to bifurcate and connect to the two subclusters, respectively, thus providing strong evidence. The YSO cluster found in this work serves as a very interesting laboratory for star formation.