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Title: UNUSUAL WATER PRODUCTION ACTIVITY OF COMET C/2012 S1 (ISON): OUTBURSTS AND CONTINUOUS FRAGMENTATION

The Solar Wind ANisotropies (SWAN) all-sky hydrogen Lyα camera on the SOlar and Heliospheric Observer (SOHO) satellite observed the hydrogen coma of comet C/2012 S1 (ISON) for most of the last month of its activity from 2013 October 24 to November 24, ending just 4 days before perihelion and its final disruption. The water production rate of the comet was determined from these observations. SOHO has been operating in a halo orbit around the Earth-Sun L1 Lagrange point since its launch in late 1995. Most water vapor produced by comets is ultimately photodissociated into two H atoms and one O atom producing a huge hydrogen coma that is routinely observed in the daily SWAN images in comets of sufficient brightness. Water production rates were calculated from 22 images over most of the last month of the pre-perihelion apparition. The water production rate increased very slowly on average from October 24.9 until November 12.9, staying between 1.8 and 3.4 × 10{sup 28} s{sup –1}, after which it increased dramatically, reaching 1.6 to 2 × 10{sup 30} s{sup –1} from November 21.6 to 23.6. It was not detected after perihelion on December 3.7 when it should have been visible. We examine the active surface area necessary tomore » explain the water production rate and its variation and are able to place constraints on the physical size of the original nucleus necessary to account for the large amount of activity from November 12.9 and until just before perihelion.« less
Authors:
;  [1] ;  [2] ; ;  [3] ;  [4]
  1. Department of Atmospheric, Oceanic, and Space Sciences, University of Michigan, 2455 Hayward Street, Ann Arbor, MI 48109-2143 (United States)
  2. Finnish Meteorological Institute, Box 503, SF-00101 Helsinki (Finland)
  3. LATMOS/IPSL, Université de Versailles Saint-Quentin, 11, Boulevard d'Alembert, F-78280 Guyancourt (France)
  4. ACRI-st, Sophia-Antipolis (France)
Publication Date:
OSTI Identifier:
22365803
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal Letters; Journal Volume: 788; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ANISOTROPY; ATOMS; BRIGHTNESS; CAMERAS; COMETS; HELIOSPHERE; HYDROGEN; LIMITING VALUES; SATELLITES; SOLAR WIND; SUN; ULTRAVIOLET RADIATION; WATER; WATER VAPOR