Physical survey of 24 Centaurs with visible photometry |
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| Affiliation: | 1. Laboratory for Atmospheric and Space Physics, University of Colorado at Boulder, 1234 Innovation Dr., Boulder, CO 80303. USA;2. Southwest Research Institute, 1050 Walnut St. #300, Boulder, CO 80302. USA;3. Lowell Observatory, 1400 W. Mars Hill Rd., Flagstaff, AZ 86001. USA;4. W. M. Keck Observatory, 65-1120 Mamalahoa Hwy., Kamuela, HI 96743. USA;1. Department of Earth and Planetary Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-0033, Japan;2. Planetary Science Institute, 1700 E. Fort Lowell, Suite 106, Tucson, AZ 85719-2395, USA;3. School of Computer Science and Engineering, The University of Aizu, 90 Kami-Iwase, Tsuruga, Ikki-machi, Aizu-Wakamatsu, Fukushima 965-8580 Japan;4. NASA Johnson Space Center, Houston TX 77058, USA;5. Centre for Astrophysics and Planetary Science, School of Physical Sciences, The University of Kent, Canterbury CT2 7NH, UK;6. Research Center for the Early Universe, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-0033, Japan |
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| Abstract: | We present optical observations of 24 Centaurs performed between 1998 and 2002 with the University of Hawaii 2.2-m telescope. This is the largest such Centaur survey to date. We report colors for all objects, and show that they cover a continuum with mean V–R color of 0.58±0.01 and standard deviation 0.15. The color distribution fits between those of the Kuiper Belt and the cometary nuclei, and seems consistent with the dynamical concept of the majority of Centaurs originating from the Kuiper Belt. We find no strong correlation between a Centaur's color and its orbital elements; there is at best a <3−σ correlation with semimajor axis, with redder Centaurs being farther from the Sun. We have calculated the phase-darkening slope parameters G for 5 Centaurs, 4 of which are reported for the first time. They range from −0.18 to 0.13. We have sufficient data to constrain the rotation periods of two Centaurs, 1999 UG5 (which we reported earlier) and 1998 SG35. We performed a comparison of the surface brightness profiles of 10 apparently-inactive Centaurs with point sources. We found no coma around these 10 objects, including C/LINEAR (2000 B4), and generally the upper limits to the dust mass loss rates are below 0.05 kg s−1. |
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