Radial Dependence of the Proto-globular Cluster Contribution to the Milky Way Formation

Chul Chung, Mario Pasquato, Sang Yoon Lee, Ugo N. Di Carlo, Deokkeun An, Suk Jin Yoon, Young Wook Lee

    Research output: Contribution to journalArticlepeer-review


    Recent interpretation of the color-magnitude diagrams of the Milky Way (MW) bulge has suggested that the observed double red-clump feature can be a natural consequence of He-enhanced stellar populations in the MW bulge. This implies that globular clusters (GCs), where the He-enhanced second-generation (SG) stars can be efficiently created, are the most likely candidate contributors of He-rich stars to the MW bulge. We extend this idea to the Galactic inner halo and investigate the fraction of the SG stars as a function of the Galactocentric distance. We use bluer blue horizontal branch (bBHB) stars, which are assumed to have originated from He-rich SG populations, as proxies of SG stars, and find that the fraction of bBHB stars increases with decreasing Galactocentric distance. Simulations of the GC evolution in the MW tidal field qualitatively support the observed trend of bBHB enhancement in the inner halo. In these simulations, the increasing tidal force with decreasing Galactocentric distance leads to stripping of stars not only from the outskirts but also from the central regions of GCs, where SG stars are more abundant. We discuss the implication and prospect of our findings concerning the formation history of the bulge and inner halo of the MW.

    Original languageEnglish (US)
    Article numberL31
    JournalAstrophysical Journal Letters
    Issue number2
    StatePublished - Oct 1 2019

    ASJC Scopus subject areas

    • Astronomy and Astrophysics
    • Space and Planetary Science


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