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

Abstract

We present detailed chemical element abundance ratios of 17 elements 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/HIRES 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 dSph, indicate that UMi 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.

arXiv comment10 pages, 7 figures, tables

References in corpus (40)

• Maps of Dust IR Emission for Use in Estimation of Reddening and CMBR Foregrounds
• The chemical composition of the Sun
• Star Formation Histories, Abundances and Kinematics of Dwarf Galaxies in the Local Group
• First stars V - Abundance patterns from C to Zn and supernova yields in the early Galaxy
• The Universal Stellar Mass-Stellar Metallicity Relation for Dwarf Galaxies
• The effective temperature scale of FGK stars. II. Teff : color : [Fe/H] calibrations
• Abundance Patterns in the Draco, Sextans and Ursa Minor Dwarf Spheroidal Galaxies
• New Grids of ATLAS9 Model Atmospheres
• Abundances and Kinematics of Field Halo and Disk Stars I: Observational Data and Abundance Analysis
• Two distinct ancient components in the Sculptor Dwarf Spheroidal Galaxy: First Results from DART
• Multi-Element Abundance Measurements from Medium-Resolution Spectra. III. Metallicity Distributions of Milky Way Dwarf Satellite Galaxies
• A Keck/DEIMOS spectroscopic survey of faint Galactic satellites: searching for the least massive dwarf galaxies
• Stellar Velocities in the Carina, Fornax, Sculptor and Sextans dSph Galaxies: Data from the Magellan/MMFS Survey
• Bipolar Supernova Explosions: Nucleosynthesis & Implication on Abundances in Extremely Metal-Poor Stars
• The evolution of the Milky Way from its earliest phases : constraints on stellar nucleosynthesis
• Abundances of 30 elements in 23 metal-poor stars
• NLTE abundances of Mn in a sample of metal-poor stars
• A new view of the dwarf spheroidal satellites of the Milky Way from VLT/FLAMES: Where are the very metal poor stars?
• The Highly Unusual Chemical Composition of the Hercules Dwarf Spheroidal Galaxy
• Chromium: NLTE abundances in metal-poor stars and nucleosynthesis in the Galaxy
• Chemistry of the Sagittarius Dwarf Galaxy: a Top-Light IMF, Outflows and the R-Process
• The Star Formation & Chemical Evolution History of the Fornax Dwarf Spheroidal Galaxy
• Kinematically Cold Populations at Large Radii in the Draco and Ursa Minor Dwarf Spheroidals
• The Star Formation History and the spatial distribution of stellar populations in the Ursa Minor Dwarf Spheroidal Galaxy
• The Chemical Evolution of the Ursa Minor Dwarf Spheroidal Galaxy
• High-Resolution Spectroscopy of Extremely Metal-Poor Stars in the Least Evolved Galaxies: Leo IV
• The s-process in the Galactic halo: the fifth signature of spinstars in the early Universe?
• The Anisotropic Distribution of M 31 Satellite Galaxies: A Polar Great Plane of Early-Type Companions
• Subaru/HDS Abundances in Three Giant Stars in the Ursa Minor Dwarf Spheroidal Galaxy
• Explaining the Ba, Y, Sr, and Eu abundance scatter in metal-poor halo stars: constraints to the r-process
• The Imprint of Reionization on the Star Formation Histories of Dwarf Galaxies
• The chemical evolution of Manganese in different stellar systems
• Detailed Abundances of Two Very Metal-Poor Stars in Dwarf Galaxies
• Neutron-capture element deficiency of the Hercules dwarf spheroidal galaxy
• Extended Star Formation in Dwarf Spheroidal Galaxies: the Cases of Draco, Sextans, and Ursa Minor
• The metal-poor Knee in the Fornax Dwarf Spheroidal Galaxy
• Manganese in dwarf spheroidal galaxies
• A comparison of the s- and r-process element evolution in local dwarf spheroidal galaxies and in the Milky Way
• All quiet in the outer halo: chemical abundances in the globular cluster Pal 3
• The Evolution of Barium and Europium in Local Dwarf Spheroidal Galaxies

Cited by in corpus (25)

• Origin of the Heaviest Elements: the Rapid Neutron-Capture Process
• TOPoS: II. On the bimodality of carbon abundance in CEMP stars. Implications on the early chemical evolution of galaxies
• The Impact of Modeling Assumptions in Galactic Chemical Evolution Models
• Chemical Abundances in the Ultra-Faint Dwarf Galaxies Grus I and Triangulum II: Neutron-Capture Elements as a Defining Feature of the Faintest Dwarfs
• Stellar Abundances for Galactic Archaeology Database IV - Compilation of Stars in Dwarf Galaxies
• The Southern Stellar Stream Spectroscopic Survey (S5): Chemical Abundances of Seven Stellar Streams
• The formation of the Milky Way halo and its dwarf satellites; a NLTE-1D abundance analysis. II. Early chemical enrichment
• The formation of the Milky Way halo and its dwarf satellites, a NLTE-1D abundance analysis. I. Homogeneous set of atmospheric parameters
• Evidence for Sub-Chandrasekhar Type Ia Supernovae from Stellar Abundances in Dwarf Galaxies
• Zinc in the Sculptor dwarf spheroidal galaxy
• The Origin of r-process Enhanced Metal-Poor Halo Stars In Now-Destroyed Ultra-Faint Dwarf Galaxies
• Simultaneous Constraints on the Star Formation History and Nucleosynthesis of Sculptor dSph
• Neutron star binary orbits in their host potential: effect on early r-process enrichment
• High Resolution Optical Spectroscopy of Stars in the Sylgr Stellar Stream
• Manganese spread in Ursa Minor as a proof of sub-classes of type Ia supernovae
• The SAMI-Fornax Dwarfs Survey III: Evolution of [$\alpha$/Fe] in dwarfs, from Galaxy Clusters to the Local Group
• The chemical connection between damped Lyman-α systems and Local Group dwarf galaxies
• Discovery of 18 stars with -3.10 < [Fe/H] < -1.45 in the Sagittarius dwarf galaxy
• The Pristine Inner Galaxy Survey (PIGS) IX. The largest detailed chemical analysis of very metal-poor stars in the Sagittarius dwarf galaxy
• Neutron-capture elements in dwarf galaxies III: A homogenized analysis of 13 dwarf spheroidal and ultra-faint galaxies
• Does the chemical signature of TYC 8442-1036-1 originate from a rotating massive star that died in a faint explosion?
• Too small to succeed: the difficulty of sustaining star formation in low-mass haloes
• Impact of NLTE on determinations of atmospheric parameters and chemical abundances of very metal-poor stars
• A relic from a past merger event in the Large Magellanic Cloud
• An ancient system hidden in the Galactic plane?