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A spectroscopic survey of late-type giants in the Milky Way disk and local halo substructure

Published online by Cambridge University Press:  01 October 2007

A. A. Sheffield ,
S. R. Majewski ,
A. M. Cheung ,
C. M. Hampton ,
J. D. Crane  and
R. J. Patterson
A. A. Sheffield
Affiliation:
Department of Physics and Astronomy, Vassar College, 124 Raymond Ave., Poughkeepsie, NY 12604-0075 email: alsheffield@vassar.edu Department of Astronomy, University of Virginia, Box 400325, Charlottesville, VA 22904-4325 email: aap5u@virginia.edu, srm4n@virginia.edu, amc4e@virginia.edu, cmh4z@virginia.edu, rjp0i@virginia.edu
S. R. Majewski
Affiliation:
Department of Astronomy, University of Virginia, Box 400325, Charlottesville, VA 22904-4325 email: aap5u@virginia.edu, srm4n@virginia.edu, amc4e@virginia.edu, cmh4z@virginia.edu, rjp0i@virginia.edu
A. M. Cheung
Affiliation:
Department of Astronomy, University of Virginia, Box 400325, Charlottesville, VA 22904-4325 email: aap5u@virginia.edu, srm4n@virginia.edu, amc4e@virginia.edu, cmh4z@virginia.edu, rjp0i@virginia.edu
C. M. Hampton
Affiliation:
Department of Astronomy, University of Virginia, Box 400325, Charlottesville, VA 22904-4325 email: aap5u@virginia.edu, srm4n@virginia.edu, amc4e@virginia.edu, cmh4z@virginia.edu, rjp0i@virginia.edu
J. D. Crane
Affiliation:
Carnegie Observatories, 813 Santa Barbara St., Pasadena, CA 91101, USA email: crane@ociw.edu
R. J. Patterson
Affiliation:
Department of Astronomy, University of Virginia, Box 400325, Charlottesville, VA 22904-4325 email: aap5u@virginia.edu, srm4n@virginia.edu, amc4e@virginia.edu, cmh4z@virginia.edu, rjp0i@virginia.edu
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Abstract

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We report the results of a survey of late-type giants aimed at understanding the nature of the disk and nearby halo Galactic stellar populations. We have obtained medium resolution (2–4 Å) spectra for 749 late K and early M giants at mid-latitudes selected from the 2MASS catalog with the FOBOS system at Fan Mountain Observatory. These spectra provide radial velocities (RVs) at the 5 km s−1 level, spectroscopic [Fe/H] good to σ[Fe/H] = 0.25 dex, and information on the relative abundances of Mg/Fe and Na/Fe in these stars. Proper motions from UCAC2 are used to search for local substructures, in particular the leading arm of the Sagittarius tidal streamer passing through the solar neighborhood. The combined proper motions and RVs yield full 6D stellar space motions. We have, by way of kinematics, relatively cleanly isolated the thick disk from the typically high velocity substructures that compose the nearby halo.

We find evidence for substructure in the kinematics and metallicities of local halo stars.

Keywords

Galaxy: structureGalaxy: kinematics and dynamicsGalaxy: formationastrometry
Type
Contributed Papers
Information
Proceedings of the International Astronomical Union , Volume 3 , Symposium S248: A Giant Step: from Milli- to Micro-arcsecond Astrometry , October 2007 , pp. 506 - 507
Copyright
Copyright © International Astronomical Union 2008

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