Spitzer Space Telescope - Directors Discretionary Time Proposal #466


Eruption of comet 17P/Holmes

Principal Investigator: William Reach 
           Institution: Caltech 

     Technical Contact: William Reach, Caltech 

Co-Investigators:
Carey Lisse, JHU/APL
Harold Weaver, JHU/APL
Jeremie Vaubaillon, Caltech

Science Category: Comets 
Observing Modes: IRS Spectral Mapping, IRS Peak-Up Imaging, MIPS Scan Map 
  Hours Approved: 12.0

Abstract:
Comet 17P/Holmes was reported to increase in brightness by 
14 magnitudes on 2007 October 24. The material produced in this 
eruption is likely to be relatively pristine material that has not 
been exposed to sunlight since formation of the comet in the outer
Solar System. Opportunities to measure such material are rare, 
and its mineralogy is of great interest. The nature of the eruption 
is unknown. Spitzer observations will distinguish between 
naturally-produced cometary dust (weak spectral features), fine 
ejecta from a violent event (strong dust features, as was found from 
Deep Impact), large meteoroids (featureless spectrum but debris trail), 
and fragmentation.