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From 6 to 16 GW and back again: a talk of Enceladus' enigmatic heat flow

Event Details

Event Dates: 

Monday, October 21, 2013 - 4:00pm

Seminar Location: 

  • JILA Auditorium

Speaker Name(s): 

Carly Howett

Speaker Affiliation(s): 

Seminar Type/Subject

Scientific Seminar Type: 

  • Astrophysical & Planetary Sciences Seminar

Event Details & Abstract: 

Enceladus’ heat flow provides a fundamental constraint on its tidal dissipation mechanisms, orbital evolution, and the physical processes that generate the plumes. An initial estimate of this value, 5.8±1.3 GW, was made by Spencer et al. (2006) using Cassini Composite Infrared Spectrometer (CIRS) 600 to 1100 cm-1 observations. This number was refined using 10 to 600 cm-1 CIRS observations to 15.8±3.1 GW by Howett et al. (2011). However, recent reanalysis of high-spatial resolution 10 to 1100 cm-1 CIRS observations of Enceladus’ active south polar region conducted by Spencer and Howett gives a heat flow of 4.2 GW. Whilst all of these heat flow estimates are much larger than those expected in a steady state, 1.1 GW (Meyer and Wisdom, 2007), their obvious discrepancy is a puzzle. Was the passive emission component simply underestimated in the 15.8 GW determination, or is there significant between-stripe endogenic emission that is excluded in the most recent estimate, or is something else going on?