Determining the potential surface distribution of CO2and H2O on the nucleus of comet 103P/Hartley 2 from EPOXI IR images
Abstract
Comet 103P/Hartley 2 is a fascinating object. It is the smallest of the comets visited by spacecraft, but had a very well-developed and productive coma. It is one of the so-called "hyperactive" comets, a category that includes short-period comets 46P/Wirtanen and 73P/Schwassman-Wachmann 3 as well as some long-period (Oort Cloud) comets. The gas production rates of these comets are near or exceed the rate that would be expected if 100% of the surface were covered in water ice. Close to perihelion, Hartley 2 was visited by the Deep Impact spacecraft as part of the extended EPOXI mission on 4 November 2010. In previous work, we showed that rather than being a typical comet with activity being dominated by H2O sublimation from the surface, similar amounts of CO2and H2O were directly sublimated from the nucleus and in fact most water was actually released by icy grains/chunks that were liberated by the rapid sublimation of CO2(Fougere et al. 2013, Icarus, 255, 688). In other previous work, we also found that the total H2O production rate from all sources had greatly decreased from apparition to apparition, 1990, 1997, and 2010 (Combi et al. 2011, ApJ Lett, 734:L6). Having nucleus activity being driven by CO2, the major carbon-bearing species in 103P/Hartley 2, distinguishes it from most comets where H2O drives the activity within ~3 AU from the Sun. We have modified our inversion scheme used to determine the potential surface distributions of the major volatile species (H2O, CO2, CO and O2) in order to study Hartley 2. For comet 67P/Churyumov-Gerasimenko, the original scheme used coma density measurements made by the ROSINA mass spectrometer when observing the solar illuminated and activated nucleus throughout the Rosetta mission (Fougere et al. 2016, MNRAS, 462, S156). For Hartley 2, we will instead constrain the inversion scheme with column densities derived from multiple remote sensing images and map the distributions of CO2and H2O on the surface of 103P/Hartley 2. Preliminary results show differences in the distributions of the active regions.
Acknowledgements We acknowledge support from grant 80NSSC17K0212 from the NASA Discovery Data Analysis Program.- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.P43C3479C
- Keywords:
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- 6008 Composition;
- PLANETARY SCIENCES: COMETS AND SMALL BODIES;
- 6045 Physics and chemistry of materials;
- PLANETARY SCIENCES: COMETS AND SMALL BODIES;
- 6207 Comparative planetology;
- PLANETARY SCIENCES: SOLAR SYSTEM OBJECTS;
- 5410 Composition;
- PLANETARY SCIENCES: SOLID SURFACE PLANETS