AAS 207th Meeting, 8-12 January 2006
Session 131 Galactic Astronomy in the SDSS
Poster, Wednesday, 9:20am-6:30pm, January 11, 2006, Exhibit Hall

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[131.05] SEGUE Target Selection, Kinematics and Distribution of Blue Horizontal Branch Stars in the Galactic Halo

G.K. Nevils (Sam Houston State University), H. N. Newberg (Rensselaer Polytechnic Institute), C. A. P. Allende Prieto (McDonald Observatory and the University of Texas at Austin), T. B. Beers (Michigan State University), Y. L. Lee, S. L. Thirupathi (Physics Frontier Center/Joint Institute for Nuclear Astrophysics), R. W. Wilhelm (Texas Tech University), B. Y. Yanny (Fermilab)

Using a sample of 654 objects selected from the Sloan Digital Sky Survey (SEGUE) plates, we evaluated and adjusted the SDSS target algorithm for Blue Horizontal Branch (BHB) stars. We then tested the spectroscopically determined surface gravity for these stars against the Lenz et al. 1998 photometric ``v-parameter" = 0.283(u-g) - 0.354(g-r) + 0.455(r-i) + 0.766(i-z). Spectroscopic and photometric determinations of the surface gravity agreed within 0.35 dex. Using surface gravity and g-r color, we estimated the distance from the center of the Galaxy and the height off of the Galactic plane for each star. We compare the galactocentric radial velocities of our star sample with known radial velocity models of the Galactic Halo. The 76 objects located at galactic latitudes (b) of -20\degr and galactic longitude (l) of 110\degr match in coordinates, distance from the Sun and radial velocity the model of the Monoceros tidal stream.

G.K.N. was supported by an REU program at Rensselaer Polytechnic Institute, NSF grant PHYS 04-53231. H.J.N and G.K.N. acknowledge support from NSF grant AST 03-07571. T.C.B., S.T., and Y.L. acknowledge support from NSF grant AST 04-06784, as well as from NSF grant PHY 02-16783, Physics Frontier Center/Joint Institute for Nuclear Astrophysics (JINA).

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