David Jewitt^1,2, Jessica Agarwal³, Jing Li³, Harold Weaver⁴, Max Mutchler⁵, and Stephen Larson⁶

¹Department of Earth, Planetary and Space Sciences, UCLA, 595 Charles Young Drive East, Los Angeles, CA 90095-1567, USA
²Department of Physics and Astronomy, University of California at Los Angeles, 430 Portola Plaza, Box 951547, Los Angeles, CA 90095-1547, USA
³Max Planck Institute for Solar System Research, Max-Planck-Str. 2, D-37191 Katlenburg-Lindau, Germany
⁴The Johns Hopkins University Applied Physics Laboratory, 11100 Johns Hopkins Road, Laurel, MD 20723, USA
⁵Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA
⁶Lunar and Planetary Laboratory, University of Arizona, 1629 E. University Boulevard, Tucson, AZ 85721-0092, USA

Splitting of the nuclei of comets into multiple components has been frequently observed but, to date, no main-belt asteroid has been observed to break up. Using the Hubble Space Telescope, we find that main-belt asteroid P/2013 R3 consists of 10 or more distinct components, the largest up to 200 m in radius (assumed geometric albedo of 0.05) each of which produces a coma and comet-like dust tail. A diffuse debris cloud with total mass ~2 × 10⁸ kg further envelopes the entire system. The velocity dispersion among the components, ΔV ~ 0.2-0.5 m s^–1, is comparable to the gravitational escape speeds of the largest members, while their extrapolated plane-of-sky motions suggest a break up between 2013 February and September. The broadband optical colors are those of a C-type asteroid. We find no spectral evidence for gaseous emission, placing model-dependent upper limits to the water production rate ≤1 kg s^–1. Breakup may be due to a rotationally induced structural failure of the precursor body.

Reference
Jewitt D, Agarwal J, Li J, Weaver H, Mutchler M and Larson S (2014) Disintegrating Asteroid P/2013 R3. The Astrophysical Journal Letters 784:L8
[doi:10.1088/2041-8205/784/1/L8]

Link to Article