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The Elemental Abundance Distributions of Milky Way Satellite Galaxies

The Elemental Abundance Distributions of Milky Way Satellite Galaxies. Evan Kirby (HF09) Caltech. Small Magellanic Cloud, HST/ACS credit: NASA, ESA, and A. Nota (STScI/ESA). in collusion with. Mike Bolte (HF90) Judy Cohen Anna Frebel Marla Geha (HF03) Raja Guhathakurta (HF92) Bob Kraft

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The Elemental Abundance Distributions of Milky Way Satellite Galaxies

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  1. The Elemental Abundance Distributions of Milky Way Satellite Galaxies • Evan Kirby (HF09) Caltech Small Magellanic Cloud, HST/ACS credit: NASA, ESA, and A. Nota (STScI/ESA)

  2. in collusion with ... • Mike Bolte (HF90) • Judy Cohen • Anna Frebel • Marla Geha (HF03) • Raja Guhathakurta (HF92) • Bob Kraft • Steve Majewski (HF92) • Connie Rockosi (HF01) • Michael Siegel • Josh Simon • Tony Sohn • Chris Sneden

  3. [Mg/Fe] [Ca/Fe] [Ca/Fe] [Ti/Fe] [Fe/H] [Mg+Ca+Ti/3Fe] Venn & Hill (2008) ESO Messenger 134, 23 [Fe/H] Venn et al. (2004) ApJ 128, 1177 Evolution of the Milky Way • Milky Way halo probably consists of dissolved dwarf satellites • Chemical abundances in satellites that survive today don't look like chemical abundances in the halo • What causes the differences? Johnston et al. (2008) ApJ 689, 936

  4. Keck + DEIMOS Method to Collect a Bunch of Abundances in dSphs flux observed synthetic [α/Fe] = +0.3 residual flux observed synthetic [α/Fe] = 0.0 residual rest wavelength (Å)

  5. Accuracy of [Fe/H]

  6. Accuracy of [X/Fe]

  7. within the solar cylinder (G dwarf problem): halo metallicity distribution: [Fe/H] [Fe/H] Δ N Δ N [O/H] [O/H] Pagel (1992) IAU Symp., Stellar Populations of Galaxies Pagel (1992) IAU Symp., Stellar Populations of Galaxies Overview of GalacticChemical Evolution

  8. . Metallicity Distributions Uranologists have detected a relic from the former universe – a star that may have been among the second generation of stars to form subsequently the Big Bang. … The team suspected that the methods used to find metal-poor stars in midget galaxies were colored in a way that caused the surveys to miss the most metal-poor stars. Team member Evan Kirby, a Caltech uranologist, highly-developed a method to estimate the metal copiousnesss of large numbers of stars at a time, making it possible to expeditiously search for the most metal-poor stars in midget galaxies. ––– http://science.knopok.net/?p=221 EK et al. (2009) ApJ 705, 328 Frebel, EK, & Simon (2010) Nature 464, 72

  9. Metallicity-Luminosity Relation

  10. Metallicity Spread vs. Luminosity

  11. Radial Gradients

  12. [O/Fe] burst quiescent burst Gilmore & Wyse (1991) ApJL 367, L55 [O/Fe] quiescent burst bursts continuous [O/Fe] continuous superimposed burst [Fe/H] Alpha Elements:Star Formation Timescales

  13. Fornax [Mg/Fe] [Si/Fe] SFR (Mʘ Myr-1) [Ca/Fe] [M/H] [Ti/Fe] age (Gyr) Dolphin et al. (2005) arXiv:astro-ph/0506430 [α/Fe] [Fe/H]

  14. Sculptor [Mg/Fe] [Si/Fe] SFR (Mʘ Myr-1) [Ca/Fe] [M/H] [Ti/Fe] age (Gyr) Dolphin et al. (2005) arXiv:astro-ph/0506430 [α/Fe] [Fe/H]

  15. Draco [Mg/Fe] [Si/Fe] SFR [Ca/Fe] [M/H] [Ti/Fe] age (Gyr) Grebel (1998) Moriond Astrophysics Meeting, Dwarf Galaxies and Cosmology [α/Fe] [Fe/H]

  16. Trends of Alpha Elements [Mg/Fe] [Si/Fe] [Ca/Fe] [Ti/Fe] [α/Fe] [Fe/H]

  17. Conclusions • Abundances trends with increasing luminosity: • Larger ‹[Fe/H]› • Larger σ(Z/Zʘ) • More gas infall • Flatter [α/Fe] at high [Fe/H] • Mass or redshift of infall into Milky Way gravitational potential may determine star formation history

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