2021A&A...650A.110M


Query : 2021A&A...650A.110M

2021A&A...650A.110M - Astronomy and Astrophysics, volume 650A, 110-110 (2021/6-1)

R-process enhancements of Gaia-Enceladus in GALAH DR3.

MATSUNO T., HIRAI Y., TARUMI Y., HOTOKEZAKA K., TANAKA M. and HELMI A.

Abstract (from CDS):


Context. The dominant site of production of r-process elements remains unclear despite recent observations of a neutron star merger. Observational constraints on the properties of the sites can be obtained by comparing r-process abundances in different environments. The recent Gaia data releases and large samples from high-resolution optical spectroscopic surveys are enabling us to compare r-process element abundances between stars formed in an accreted dwarf galaxy, Gaia-Enceladus, and those formed in the Milky Way.
Aims. Our aim is to understand the origin of r-process elements in Gaia-Enceladus.
Methods. We first constructed a sample of stars so that our study on Eu abundance is not affected by the detection limit. We then kinematically selected 76 Gaia-Enceladus stars and 81 in situ stars from the Galactic Archaeology with HERMES (GALAH) DR3, of which 47 and 55 stars, respectively, can be used to study Eu reliably.
Results. Gaia-Enceladus stars clearly show higher ratios of [Eu/Mg] than in situ stars. High [Eu/Mg] along with low [Mg/Fe] are also seen in relatively massive satellite galaxies such as the LMC, Fornax, and Sagittarius dwarfs. On the other hand, unlike these galaxies, Gaia-Enceladus does not show enhanced [Ba/Eu] or [La/Eu] ratios suggesting a lack of significant s-process contribution. From comparisons with simple chemical evolution models, we show that the high [Eu/Mg] of Gaia-Enceladus can naturally be explained by considering r-process enrichment by neutron-star mergers with delay time distribution that follows a power-law similar to type Ia supernovae but with a shorter minimum delay time.

Abstract Copyright: © ESO 2021

Journal keyword(s): stars: abundances - Galaxy: halo - Galaxy: abundances - Galaxy: kinematics and dynamics - nuclear reactions - nucleosynthesis - abundances

Simbad objects: 8

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Number of rows : 8
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2023
#notes
1 NAME Sculptor Dwarf Galaxy G 01 00 09.4 -33 42 32   9.79 8.6 8.81   ~ 1265 4
2 NAME Fornax Dwarf Spheroidal G 02 39 59.3 -34 26 57   9.02 7.4     ~ 1651 1
3 NAME Reticulum II G 03 35 42.1 -54 02 57           ~ 250 0
4 NAME LMC G 05 23 34.6 -69 45 22     0.4     ~ 16415 1
5 GrW 170817 GWE 13 09 48.0850 -23 22 53.343           ~ 1549 0
6 NAME Dra dSph G 17 20 14.335 +57 55 16.39   12.40 10.6     ~ 1269 1
7 NAME SDG G 18 55 03.1 -30 28 42   4.5 3.6     ~ 2019 2
8 NAME Gaia Enceladus-Sausage St* ~ ~           ~ 338 0

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2022.12.08-01:57:53

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