NOAO >   Observing Info >   Approved Programs >   2011A-0280

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Proposal Information for 2011A-0280


PI: David Sand, UC Santa Barbara, dave.j.sand@gmail.com
Address: Physics Department, Santa Barbara, CA 93106, USA

CoI: Beth Willman, Haverford College

Title: Diagnosing youth: Gemini spectroscopy to verify the young stellar populations in Leo IV and Canes Venatici I

Abstract: We propose to use Gemini/GMOS spectroscopy to confirm the presence of young stellar populations in two, ultra-faint Milky Way dwarf galaxies: Leo IV (M_V=-5.5, 160 kpc) and Canes Venatici I (M_V=- 7.9, 220 kpc; CVn I). These two outer halo satellites are, like all of the Milky Way's ~20 other dwarf satellites, dominated by an old, >10 Gyr stellar population. Unlike the other M_V > -8 satellites, Leo IV and CVn I have been claimed to also possess a small (< 10% in luminosity), spatially clumped population of 1 - 2 Gyr old stars. The presence of such stars in these low luminosity satellites would provide a remarkable test of models for the impact of supernova feedback and ionizing radiation on the baryon content of dwarf galaxies at the very bottom of the formation hierarchy. A wrinkle in these findings is that a cluster of unresolved blue galaxies could possibly be masquerading as young stars in each of these objects. The proposed observations will either confirm, or rule out, this scenario.


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NOAO >   Observing Info >   Approved Programs >   2011A-0280

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