NOAO >   Observing Info >   Approved Programs >   2009B-0222

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Proposal Information for 2009B-0222


PI: Zeljko Ivezic, University of Washington, ivezic@astro.washington.edu
Address: Department of Astronomy, PO Box 351580, Seattle, WA 98195-1580, USA

CoI: Kathy Vivas, Centro de Investig. de Astronomia (CIDA)
CoI: Branimir Sesar, University of Washington

Title: The Most Distant Sub-structure in the Galactic Halo

Abstract: Using the multi-epoch SDSS data (Stripe 82), a very significant overdensity of RR Lyrae stars was recently discovered. This clump has the record of being the most distant from the Sun discovered to the date in the Milky Way. Its mean distance is 90 kpc from the Sun. We are proposing to use Gemini + GMOS to obtain spectra of several of the RR Lyrae stars in this clump. This would allow us: (i) to confirm that the sub-structure is coherent in velocity space, and (ii) to investigate its properties (metallicities and velocity dispersions) and hence, its origin. The detailed studies of halo sub-structures, such as the one we are proposing to observe with Gemini, are important to test the hierarchical models of Galaxy formation.


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NOAO >   Observing Info >   Approved Programs >   2009B-0222

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