1. Centaur Physical Properties and Dynamics Emily Schaller (University of Arizona) Nader Haghighipour (University of Hawaii) Mike Brown (Caltech)

2. Centaur Physical Properties (Visible) B-R color bimodality (Peixinho et al., 2003; Tegler et al., 2003) – Colors do not correlate with dynamical properties (Tegler et al. 2008)

3. H-K (1.5-2.5 micron) spectra show featureless to moderate absorptions at 1.5 and 2.0 microns due to water ice (Barkume et al. 2008, Guilbert et al. 2009) Spectra can be parameterized by a mixture of water ice and a dark continuum component Centaur Physical Properties (Infrared) Pure water ice Featureless Guilbert et al. 2009

4. Keck NIRC H-K centaur spectral survey

5. Centaur Infrared Spectra Relative Reflectance Parameterized all 22 spectra with a mixture of water ice + dark sloped continuum component

6. Water ice and visible color B-R colors from Tegler et al. 2008

7. Water Ice and Albedo Albedos from Stansberry et al. 2008

8. Water ice and diameter Diameters from Stansberry et al. 2008

9. Water Ice and Orbital Elements

10. Centaur Dynamical Simulations Integrated 100 clones of each centaur for 100 million years Median dynamical lifetime for each centaur Compare with physical properties

11. Water Ice Fraction vs. Dynamical Lifetime

12. Conclusions Centaur water ice fraction does not correlate with visible color – Gray and red centaur populations have water ice and flat spectra – >Exposed water ice from collisions or sublimation cannot account for blue/gray colors Water ice fraction ranges from 0-40% (wider range than for non-Haumea family and KBOs) Physical properties do not correlate with object dynamical lifetimes

13. Dynamical Lifetime and Color