Chemical Abundance Analysis of Tucana III, the Second r-process
Enhanced Ultra-Faint Dwarf Galaxy
release_rkcleds33bfsxo7ajqja5pkvpy
by
J. Marshall, T. Hansen, J. Simon, T. Li, R. Bernstein, K. Kuehn, A.
Pace, D. DePoy, A. Palmese, A. Pieres, L. Strigari, A. Drlica-Wagner (+43 others)
2018
Abstract
We present a chemical abundance analysis of four additional confirmed member
stars of Tucana III, a Milky Way satellite galaxy candidate in the process of
being tidally disrupted as it is accreted by the Galaxy. Two of these stars are
centrally located in the core of the galaxy while the other two stars are
located in the eastern and western tidal tails. The four stars have chemical
abundance patterns consistent with the one previously studied star in Tucana
III: they are moderately enhanced in r-process elements. The
non-neutron-capture elements generally follow trends seen in other dwarf
galaxies, including a metallicity spread of 0.44 dex and the expected trend in
α-elements, i.e., the lower metallicity stars have higher Ca and Ti
abundance. Overall, the chemical abundance patterns of these stars suggest that
Tucana III was an ultra-faint dwarf galaxy, and not a globular cluster, before
being tidally disturbed. As is the case for the one other galaxy dominated by
r-process enhanced stars, Reticulum II, Tucana III's stellar chemical
abundances are consistent with pollution from ejecta produced by a binary
neutron star merger.
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