NOAO >   Observing Info >   Approved Programs >   2006B-0571

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Proposal Information for 2006B-0571


PI: Mei-Yin Chou, University of Virginia, srm4n@virginia.edu
Address: Dept. of Astronomy, P.O. Box 400325, Charlottesville, VA 22903-0818, USA

CoI: Steven Majewski, University of Virginia
CoI: Verne V. Smith, NOAO
CoI: Katia Cunha, NOAO
CoI: Richard J. Patterson, University of Virginia
CoI: David Martinez Delgado, Instituto de Astrofisica de Canarias

Title: Chemical Trends in Halo Tidal Streams

Abstract: Though it is now clear that accretion of dwarf galaxies likely played a prominent role in creating the Milky Way (MW) halo, the chemical abundance patterns of current MW satellites are typically very different than those of halo stars, and the reason for these differences remains a matter of speculation. We propose to test the bridge from dwarf galaxy to halo star \it directly by exploring chemical trends along the tidal tails of disrupting dwarf galaxies. Our initial abundance analysis on debris from the Sagittarius (Sgr) dwarf galaxy has already revealed a significant [Fe/H] trend along the leading arm from the core to debris stripped some 2 Gyr ago from the satellite. This trend vividly demonstrates the origin of differences between current dwarf galaxies and the stars they contributed to the halo and presents a new method for mapping the star formation and dynamical histories of galaxies. We propose to improve our analysis of the Sgr stream by undertaking echelle resolution observations of stars in the dynamically simpler \it trailing arm of Sgr. We also plan to repeat this analysis on the Monoceros (Mon)/Canis Major/Argo and Tri-And systems to: (1) establish whether Mon is a satellite tidal stream and not the Galactic warp, (2) test the putative associations of Canis Major, Argo and Tri- And with Mon, and (3) search for abundance variations along the Mon stream like those seen for the Sgr stream.


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