37th DPS Meeting, 4-9 September 2005
Session 56 TNOs and Centaurs
Poster, Thursday, September 8, 2005, 6:00-7:15pm, Music Recital Room

[Previous] | [Session 56] | [Next]

[56.05] Centaur Colors: New Data and Analysis

G. J. Consolmagno (Specola Vaticana), W. Romanishin (University of Oklahoma), S. C. Tegler (Northern Arizona University)

We report B-R colors for three newly discovered Centaurs (minor bodies orbiting between Jupiter and Neptune) measured at the Vatican Advanced Technology Telescope on Mt. Graham, Arizona. For 60558, B-R = 1.4 ± 0.04; for 55576, B-R = 1.81 ± 0.04; and for 2003 WL7, B-R = 1.23 ± 0.04. With these data, we now have colors of all Centaurs brighter than 22nd magnitude in R discovered to date except the recently discovered 2004 PY42: 26 objects in all.

Given the drop in the discovery rate for Centaurs bright enough to be well observed with 2 meter class telescopes (only two such objects found since the end of 2003), a review of these data appears to be timely. We find excellent agreement for B-R colors of the 15 objects in this data set observed both by us and by other groups. The whole sample of 26 Centaur B-R colors shows a strong bimodality, split into distinct red and gray groups, in agreement with several previous studies. Although any differences in the orbital parameters of the red and gray groups may be hidden by large dispersion of parameters, there is a hint that the red Centaurs have a lower inclination distribution than the gray and perhaps have slightly larger semimajor axes. This, plus the observed colors of other classes of Kuiper belt objects, leads us to speculate on a two-source model for the origin of Centaurs. The red ones may have arisen from the dynamically cold classical belt, and the gray ones from the Plutinos or the scattered disk.

[Previous] | [Session 56] | [Next]

Bulletin of the American Astronomical Society, 37 #3
© 2004. The American Astronomical Soceity.