The 19 February 2016 Outburst of Comet 67P/C-G: Heating of the Coma by Dust Raised in an Avalanche
Abstract
The Microwave Instrument for the Rosetta Orbiter (MIRO) is a U.S. instrument with French, German, and Taiwanese participation. It is on the European Space Agency's Rosetta spacecraft which, from August 2014 through September 2016, was flying along side comet 67P/Churyumov-Gerasimenko. MIRO is designed to study the nucleus and coma of the comet as a coupled system. It makes broad-band continuum measurements at 190 and 563 GHz (1.6 and 0.5 mm) of thermal emission from the nucleus and large dust particles in the coma. MIRO also has a high resolution (44 kHz) spectrometer fixed tuned to submillimeter lines of H2O, H217O, H218O, CO, NH3, and three CH3OH transitions, allowing us to determine the abundance, velocity, and temperature of these species in the coma.On 19 February 2016, most of the instruments on Rosetta observed a strong outburst in activity (Grün et al. 2016, MNRAS). The first signs of this outburst were a large cloud of dust rising from the nucleus, and an increase in the excitation temperature of gas in the coma from ~20 to ~50 K. A few minutes later there is evidence of an increase in gas density. We previously suggested that this sequence of events is best explained by a landslide or collapse on the nucleus which first raises dust. The dust then radiatively heats the entire coma, after which nucleus ices, newly exposed by the landslide, begin sublimating and increasing coma gas density. We will present our latest calculations on the feasibility of small dust particles (which have high temperature) radiatively increasing the temperature of water molecules in the coma, and will compare predicted with observed gas temperatures.
- Publication:
-
AAS/Division for Planetary Sciences Meeting Abstracts #49
- Pub Date:
- October 2017
- Bibcode:
- 2017DPS....4941505H