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| Paper: |
Washington Photometry and Hectochelle Spectroscopy of Giant Stars in the Leo II dSph Galaxy |
| Volume: |
352, New Horizons in Astronomy: Frank N. Bash Symposium 2005 |
| Page: |
285 |
| Authors: |
Siegel, M.H.; Majewski, S.R. |
| Abstract: |
We have used the KPNO 4-meter telescope to obtain high-precision Washington+DDO51 photometry over a five square degree region centered on the Leo II dSph galaxy. We identify Leo II red giant branch (RGB) star candidates using two-color and color-magnitude diagrams (CMDs), a very reliable method of identifying giant stars amongst the overwhelming foreground of Galactic dwarfs. The spatial distribution of the giant candidates follows the canonical single-mass King profile in the inner regions of Leo II, but shows faint extended structure beyond the nominal limiting radius. MMT Hectochelle spectra demonstrate that the majority of our Leo II giant candidates have radial velocities near that of Leo II, including 3-5 stars beyond Leo II's King limiting radius. The observed extended structure of Leo II either is the result of tidal disruption during a past perigalacticon or traces an extended halo of dark matter. With high precision (~1 km s−1) radial velocities, we hope to clarify these issues. |
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