Evidence from APOGEE for the presence of a major building block of the halo buried in the inner Galaxy

Horta, Danny; Schiavon, Ricardo P.; Mackereth, J. Ted; Pfeffer, Joel; Mason, Andrew C.; Kisku, Shobhit; Fragkoudi, Francesca; Allende Prieto, Carlos; Cunha, Katia; Hasselquist, Sten; Holtzman, Jon; Majewski, Steven R.; Nataf, David; O'Connell, Robert W.; Schultheis, Mathias; Smith, Verne V.
Bibliographical reference

Monthly Notices of the Royal Astronomical Society

Advertised on:
1
2021
Number of authors
16
IAC number of authors
1
Citations
124
Refereed citations
106
Description
We report evidence from APOGEE for the presence of a new metal-poor stellar structure located within ∼4 kpc of the Galactic Centre. Characterized by a chemical composition resembling those of low-mass satellites of the Milky Way, this new inner Galaxy structure (IGS) seems to be chemically and dynamically detached from more metal-rich populations in the inner Galaxy. We conjecture that this structure is associated with an accretion event that likely occurred in the early life of the Milky Way. Comparing the mean elemental abundances of this structure with predictions from cosmological numerical simulations, we estimate that the progenitor system had a stellar mass of ∼5 × 108 M☉, or approximately twice the mass of the recently discovered Gaia-Enceladus/Sausage system. We find that the accreted:in situ ratio within our metal-poor ([Fe/H] < -0.8) bulge sample is somewhere between 1:3 and 1:2, confirming predictions of cosmological numerical simulations by various groups.
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Chemical Abundances in Stars

Stellar spectroscopy allows us to determine the properties and chemical compositions of stars. From this information for stars of different ages in the Milky Way, it is possible to reconstruct the chemical evolution of the Galaxy, as well as the origin of the elements heavier than boron, created mainly in stellar interiors. It is also possible to

Carlos
Allende Prieto