Jupiter Impacts in the Thermal-Infrared: Comparing Atmospheric Responses in 1994, 2009 and 2010
Abstract
Rising plumes and high temperature shocks resulting from collisions of primitive bodies with Jupiter produce dramatic perturbations to the atmospheric structure and chemistry. Spectroscopy of Jupiter's 7-25 µm spectrum, from NASA/IRTF, VLT and Gemini, demonstrates that these atmospheric perturbations differ substantially between impacts and can reveal the nature of the impactor. VLT/VISIR spectroscopy of the July 2009 impact site revealed elevated abundances of ethane (and possibly acetylene), the products of shock-induced chemistry in a reducing environment (i.e., an absence of water, suggesting an asteroidal origin in 2009). This is counter to observations of the 1994 Shoemaker-Levy 9 (SL9) collisions, where no increase in hydrocarbons was observed, due to the formation of CO in a water-rich environment (consistent with a cometary origin). VLT and Gemini imaging demonstrated no excess thermal energy in the upper stratosphere following the 2009 and June 2010 impact events, and yet SL9 left traces of high-altitude heating at multiple impact sites. The 2010 event was considerably smaller in scale, generating a shock wave too small to penetrate the ammonia cloud depths to loft NH3 into the lower stratosphere, as was observed for the SL9 and 2009 impacts. Nor did the 2010 impact generate high-altitude particulate debris, which was clearly evident in the SL9 and 2009 impact sites. Finally, minearological differences between the 1994 and 2009 debris have been revealed by Gemini spectroscopy, indicating the presence of silicates in both cases, but also silicas in the 2009 collision.
We present results for the fate of stratospheric ammonia, hydrocarbons and particulates from the 2009 impact, plus the non-detection of thermal signatures of the 2010 event by Gemini and VLT. These are compared to SL9 results to describe the different origins of Jupiter impactors and the differences in the atmospheric response. * Fletcher is supported by a Glasstone Science Fellowship.- Publication:
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AAS/Division for Planetary Sciences Meeting Abstracts #42
- Pub Date:
- October 2010
- Bibcode:
- 2010DPS....42.3103F