NOAO >   Observing Info >   Approved Programs >   2016B-0089

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Program Information for 2016B-0089


PI: Alexander Ji, MIT, alexji@mit.edu
Address: Division of Astrophysics, Department of Physics, Cambridge, MA, 02139 USA

CoI: Joshua Simon, Carnegie Institution of Washington
CoI: Anna Frebel, MIT
CoI: Terese Hansen, Carnegie Institution of Washington

Title: Detailed Chemical Abundances of the Ultra-faint Dwarf Galaxy Triangulum II

Abstract: Ultra-faint dwarf galaxies are unique probes of the earliest chemical evolution and star formation processes. We propose to observe the two brightest stars in the newly discovered ultra-faint dwarf galaxy Triangulum II using 9 hours on Gemini-N/GRACES. The high-resolution spectra will allow us to determine chemical abundances of over a dozen elements, including carbon, calcium, and barium. Such detailed abundances will yield insight into the formation of the Milky Way's stellar halo, determine whether Tri II is a relic from the era of first galaxies, clarify the astrophysical site of r-process nucleosynthesis, and probe the nature of the first stars. Tri II is an especially promising target as its luminosity and half-light radius are similar to the only other known first galaxy candidate Segue 1. Confirming Tri II as a first galaxy would be a first step towards studying variations among first galaxies and towards understanding what makes first galaxies distinct from systems with more extended star formation histories.

Program Type: Standard/Galactic

Scheduled Nights:
Run 1 (2016B):  GEM-N-SVC/GRACES -- 9hrs band 2 (GN-2016B-Q-44)


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NOAO >   Observing Info >   Approved Programs >   2016B-0089

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