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Title: Exploring the Evolution of Massive Clumps in Simulations That Reproduce the Observed Milky Way α-element Abundance Bimodality
Abstract

The Milky Way (MW) stellar disk has both a thin and a thick component. The thin disk is composed mostly of younger stars (≲8 Gyr) with a lower abundance ofα-elements, while the thick disk contains predominantly older stars (≳8–12 Gyr) with a higherαabundance, giving rise to anα-bimodality most prominent at intermediate metallicities. A proposed explanation for the bimodality is an episode of clumpy star formation, where high-αstars form in massive clumps that appear in the first few billion years of the MW’s evolution, while low-αstars form throughout the disk and over a longer time span. To better understand the evolution of clumps, we track them and their constituent stars in two clumpy MW simulations that reproduce theα-abundance bimodality, one with 10% and the other with 20% supernova feedback efficiency. We investigate the paths that these clumps take in the chemical space ([O/Fe]–[Fe/H]) as well as their mass, star formation rate (SFR), formation location, lifetime, and merger history. The clumps in the simulation with lower feedback last longer on average, with several lasting hundreds of millions of years. Some of the clumps do not reach high-α, but the ones that do on average have a higher SFR, longer lifetime, greater mass, and form closer to the Galactic center than the ones that do not. Most clumps that reach high-αmerge with others and eventually spiral into the Galactic center, but shed stars along the way to form most of the thick-disk component.

 
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Award ID(s):
1908331
NSF-PAR ID:
10440378
Author(s) / Creator(s):
; ; ; ;
Publisher / Repository:
DOI PREFIX: 10.3847
Date Published:
Journal Name:
The Astrophysical Journal
Volume:
953
Issue:
2
ISSN:
0004-637X
Format(s):
Medium: X Size: Article No. 128
Size(s):
["Article No. 128"]
Sponsoring Org:
National Science Foundation
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