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An inefficient dwarf: chemical abundances and the evolution of the Ursa Minor dwarf spheroidal galaxy

Ural, Ugur; Cescutti, Gabriele; Koch, Andreas; Kleyna, Jan; Feltzing, Sofia LU and Wilkinson, Mark I. (2015) In Monthly Notices of the Royal Astronomical Society 449(1). p.761-770
Abstract
We present detailed chemical element abundance ratios of 17 elements with eight <= Z <= 60 in three metal-poor stars in the Ursa Minor dwarf spheroidal galaxy, which we combine with extant data from the literature to assess the predictions of a novel suite of galaxy chemical evolution models. The spectroscopic data were obtained with the Keck/High-Resolution Echelle Spectrograph instrument and revealed low metallicities of [Fe/H]= -2.12, -2.13 and -2.67 dex. While the most metal-poor star in our sample shows an overabundance of [Mn/Fe] and other Fe-peak elements, our overall findings are in agreement with previous studies of this galaxy: elevated values of the [alpha/Fe] ratios that are similar to, or only slightly lower than, the... (More)
We present detailed chemical element abundance ratios of 17 elements with eight <= Z <= 60 in three metal-poor stars in the Ursa Minor dwarf spheroidal galaxy, which we combine with extant data from the literature to assess the predictions of a novel suite of galaxy chemical evolution models. The spectroscopic data were obtained with the Keck/High-Resolution Echelle Spectrograph instrument and revealed low metallicities of [Fe/H]= -2.12, -2.13 and -2.67 dex. While the most metal-poor star in our sample shows an overabundance of [Mn/Fe] and other Fe-peak elements, our overall findings are in agreement with previous studies of this galaxy: elevated values of the [alpha/Fe] ratios that are similar to, or only slightly lower than, the halo values but with SN Ia enrichment at very low metallicity, as well as an enhancement of the ratio of first to second peak neutron capture elements [Y/Ba] with decreasing metallicity. The chemical evolution models which were tailored to reproduce the metallicity distribution function of the dwarf spheroidal, indicate that Ursa Minor had an extended star formation which lasted nearly 5 Gyr with low efficiency and are able to explain the [Y/Ba] enhancement at low metallicity for the first time. In particular, we show that the present-day lack of gas is probably due to continuous loss of gas from the system, which we model as winds. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
galaxies: abundances, galaxies: dwarf, galaxies: evolution, galaxies:, individual: UMi I dSph, Local Group
in
Monthly Notices of the Royal Astronomical Society
volume
449
issue
1
pages
761 - 770
publisher
Wiley-Blackwell
external identifiers
  • wos:000355345600055
  • scopus:84930845468
ISSN
1365-2966
DOI
10.1093/mnras/stv294
language
English
LU publication?
yes
id
20e3466c-2ae4-4436-80cd-ecb94d863df2 (old id 7613665)
date added to LUP
2015-07-21 13:31:52
date last changed
2017-11-12 03:02:33
@article{20e3466c-2ae4-4436-80cd-ecb94d863df2,
  abstract     = {We present detailed chemical element abundance ratios of 17 elements with eight &lt;= Z &lt;= 60 in three metal-poor stars in the Ursa Minor dwarf spheroidal galaxy, which we combine with extant data from the literature to assess the predictions of a novel suite of galaxy chemical evolution models. The spectroscopic data were obtained with the Keck/High-Resolution Echelle Spectrograph instrument and revealed low metallicities of [Fe/H]= -2.12, -2.13 and -2.67 dex. While the most metal-poor star in our sample shows an overabundance of [Mn/Fe] and other Fe-peak elements, our overall findings are in agreement with previous studies of this galaxy: elevated values of the [alpha/Fe] ratios that are similar to, or only slightly lower than, the halo values but with SN Ia enrichment at very low metallicity, as well as an enhancement of the ratio of first to second peak neutron capture elements [Y/Ba] with decreasing metallicity. The chemical evolution models which were tailored to reproduce the metallicity distribution function of the dwarf spheroidal, indicate that Ursa Minor had an extended star formation which lasted nearly 5 Gyr with low efficiency and are able to explain the [Y/Ba] enhancement at low metallicity for the first time. In particular, we show that the present-day lack of gas is probably due to continuous loss of gas from the system, which we model as winds.},
  author       = {Ural, Ugur and Cescutti, Gabriele and Koch, Andreas and Kleyna, Jan and Feltzing, Sofia and Wilkinson, Mark I.},
  issn         = {1365-2966},
  keyword      = {galaxies: abundances,galaxies: dwarf,galaxies: evolution,galaxies:,individual: UMi I dSph,Local Group},
  language     = {eng},
  number       = {1},
  pages        = {761--770},
  publisher    = {Wiley-Blackwell},
  series       = {Monthly Notices of the Royal Astronomical Society},
  title        = {An inefficient dwarf: chemical abundances and the evolution of the Ursa Minor dwarf spheroidal galaxy},
  url          = {http://dx.doi.org/10.1093/mnras/stv294},
  volume       = {449},
  year         = {2015},
}