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Title: Hubble space telescope investigation of main-belt comet 133P/Elst-Pizarro

We report new observations of the prototype main-belt comet (active asteroid) 133P/Elst-Pizarro taken at high angular resolution using the Hubble Space Telescope. The object has three main components: (1) a point-like nucleus; (2) a long, narrow antisolar dust tail; and (3) a short, sunward anti-tail. There is no resolved coma. The nucleus has a mean absolute magnitude H{sub V} = 15.70 ± 0.10 and a light curve range ΔV = 0.42 mag, the latter corresponding to projected dimensions 3.6 × 5.4 km (axis ratio 1.5:1) at the previously measured geometric albedo of 0.05 ± 0.02. We explored a range of continuous and impulsive emission models to simultaneously fit the measured surface brightness profile, width, and position angle of the antisolar tail. Preferred fits invoke protracted emission, over a period of 150 days or less, of dust grains following a differential power-law size distribution with index 3.25 ≤q ≤ 3.5 and with a wide range of sizes. Ultra-low surface brightness dust projected in the sunward direction is a remnant from emission activity occurring in previous orbits, and consists of the largest (≥cm-sized) particles. Ejection velocities of one-micron-sized particles are comparable to the ∼1.8 m s{sup –1} gravitational escape speed of themore » nucleus, while larger particles are released at speeds less than the gravitational escape velocity. The observations are consistent with, but do not prove, a hybrid hypothesis in which mass loss is driven by gas drag from the sublimation of near-surface water ice, but escape is aided by centripetal acceleration from the rotation of the elongated nucleus. No plausible alternative hypothesis has been identified.« less
Authors:
;  [1] ;  [2] ;  [3] ;  [4] ;  [5]
  1. Department of Earth, Planetary and Space Sciences, University of California at Los Angeles, 595 Charles Young Drive East, Los Angeles, CA 90095-1567 (United States)
  2. The Johns Hopkins University Applied Physics Laboratory, 11100 Johns Hopkins Road, Laurel, MD 20723 (United States)
  3. Max Planck Institute for Solar System Research, Justus-von-Liebig-Weg 3, 37077 Gottingen (Germany)
  4. Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States)
  5. Lunar and Planetary Laboratory, University of Arizona, 1629 East University Boulevard, Tucson, AZ 85721-0092 (United States)
Publication Date:
OSTI Identifier:
22340257
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astronomical Journal (New York, N.Y. Online); Journal Volume: 147; Journal Issue: 5; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ACCELERATION; ASTEROIDS; BRIGHTNESS; COMETS; COMPARATIVE EVALUATIONS; DISTRIBUTION; DUSTS; ICE; MASS TRANSFER; ORBITS; PLANETS; RADIO TELESCOPES; RESOLUTION; ROTATION; SPACE; STELLAR WINDS; SURFACES; VELOCITY; VISIBLE RADIATION; WATER