Lithium and Beryllium in the Gaia-Enceladus Galaxy
Date Issued
2020
Author(s)
Abstract
Data from Gaia DR2 and APOGEE surveys revealed a relatively new component in
the inner Galactic halo, which is likely the dynamical remnant of a disrupted
dwarf galaxy named Gaia-Enceladus that collided with the Milky Way about 10
Gyrs ago. This merging event offers an extraordinary opportunity to study
chemical abundances of elements in a dwarf galaxy, since they are generally
hampered in external galaxies. Here, we focus on Li and Be in dwarf stars which
are out of reach even in Local Group galaxies.Searching in GALAH, Gaia-ESO
survey and in literature, we found several existing 7Li abundance
determinations of stars belonging to the Gaia-Enceladus galaxy. The 7Li
abundances of stars at the low metallicity end overlap with those of the
Galactic halo.These are effective extragalactic 7Li measurements, which suggest
that the {\it Spite plateau} is universal, as is the cosmological Li problem.
We found a Li-rich giant out of 101 stars, which suggests a small percentage
similar to that of the Milky Way. We also collect 9Be abundances for a
subsample of 25 Gaia-Enceladus stars from literature. Their abundances share
the Galactic [Be/H] values at the low metallicity end but grow slower with
[Fe/H] and show a reduced dispersion. This suggests that the scatter observed
in the Milky Way could reflect the different \beix\ evolution patterns of
different stellar components which are mixed-up in the Galactic halo.
Volume
496
Issue
3
Start page
2902
Issn Identifier
0035-8711
Rights
open.access
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