MAIN-BELT COMET P/2008 R1 (GARRADD)
- Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822 (United States)
We present a study of the newly discovered main-belt comet P/2008 R1 (Garradd), an object with the dynamical characteristics of an asteroid and the physical characteristics of a comet. Photometry sets a limit to the effective radius of the nucleus at r{sub e} < 0.7 km (red geometric albedo 0.05 assumed). The coma shows a secular fading in our data caused by the escape of dust particles from the near-nucleus environment. The optical reflection spectrum is a nearly neutral continuum devoid of gaseous emission lines, from which we derive a limit to the cyanide (CN) radical production rate of Q {sub CN}< 1.4 x 10{sup 23} s{sup -1} and infer a mass-loss rate <1.5 kg s{sup -1} at the time of our observations. Unlike the first-reported main-belt comets, P/2008 R1 is not dynamically stable. The nearby 8:3 mean-motion resonance with Jupiter induces dynamical instability on timescales 20-30 Myr. Hence, we conclude that P/2008 R1 has recently arrived from a more stable source elsewhere. The high Tisserand parameter of the orbit (in fact, with T{sub J} = 3.216 it is the highest of any comet) points to a source in the asteroid belt itself, instead of in the Kuiper belt (putative source of the Jupiter family comets). We infer that P/2008 R1 is an icy body from the outer asteroid belt in which sublimation has been triggered by rising temperatures resulting from a decreasing perihelion distance.
- OSTI ID:
- 21269192
- Journal Information:
- Astronomical Journal (New York, N.Y. Online), Vol. 137, Issue 5; Other Information: DOI: 10.1088/0004-6256/137/5/4313; Country of input: International Atomic Energy Agency (IAEA); ISSN 1538-3881
- Country of Publication:
- United States
- Language:
- English
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