20-24 March 2023
Haus H, Telegrafenberg
Europe/Berlin timezone

The Cosmic Hunt for Members in the Outskirts of Ultra Faint Dwarf Galaxies: Ursa Major I, Coma Berenices, and Boötes I

22 Mar 2023, 10:31
Haus H, Telegrafenberg

Haus H, Telegrafenberg

Potsdam, Germany
Poster SESSION 3 : Dwarf galaxies: dwarf spheroidal, ultra-faint dwarfs, dwarf irregulars SESSION 3 : Dwarf galaxies: dwarf spheroidal, ultra-faint dwarfs, dwarf irregulars


Fletcher Waller (University of Victoria)


The chemical abundance patterns exhibited by stars in Ultra-Faint Dwarf (UFD) galaxies can provide a wealth of information about the evolutionary history of UFDs, including what dynamical history the stars in a UFD may have experienced. Of particular interest are stars in the outer regions of UFDs because they may hold evidence of tidal stripping, mergers, or other mechanisms; and because of the localized nature of enrichment events in UFDs, it is important to use every available star in analyses of UFD histories. I present detailed abundances from high-resolution spectroscopy with Gemini/GRACES for five new stars in three UFDs, Coma Berenices (Com Ber), Ursa Major I (UMaI), and Boötes I (BooI), where four of our five stars are at distances greater than two half-light radii. The chemistries for all three galaxies are consistent with the outermost stars forming in the central regions, then moving to their current locations through dynamical mechanisms. In BooI, the lower metallicity and lack of strong carbon enrichment of its outermost stars could also be evidence of a dwarf galaxy merger. The abundance ratios and chemical patterns of the stars in Com Ber are consistent with contributions from SN Ia (including an unusually high Ni value), which is unexpected for its star formation history and in conflict with previous suggestions that this system evolved chemically from a single core collapse supernova event. We look forward to the new GHOST (Gemini High-resolution Optical SpecTrograph), which will make these types of chemical abundance-quality observations possible for many more stars in UFDs.

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Primary author

Fletcher Waller (University of Victoria)


Dr Kim Venn (University of victoria) Mr Federico Sestito (University of Victoria) Jaclyn Jensen (University of Victoria) Asya Borukhovetskaya (University of Victoria) Dr Chris Hayes (NRC Herzberg Astronomy & Astrophysics) Dr Alan McConnachie (NRC-Herzberg Astronomy & Astrophysics) Dr Julio Navarro (University of Victoria) Dr Collin Kielty

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