Comet Rotation

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Comet Rotation

• Béatrice E.A. Mueller

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WHY study rotation?

• period is a physical parameter
• needed for interpretation of other observations
• gives insight into structural parameters which
  affect the damping time
• can be used to constrain bulk density
• spin evolution is expected in comets (e.g.
  Samarasinha)

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Comet 9P/Tempel 1

• Target of successful Deep Impact mission (July 4,
  2005) and future NExT mission.
• Seems to have changed its rotation period
  substantially, indicated by observations. Needs
  to be confirmed. (Mueller, Samarasinha, Farnham,
  Belton)

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A simple model (by Michael Belton)
S P I N R A T E
?
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10P/Tempel 2

• Extensively observed
• Seemed to have a small change in period between
  1988 1994 (Mueller and Ferrin 1996)
• Change confirmed by Mueller and Samarasinha
  (2006)
• No change observed between 1994 and 2000/2001 and
  2004
• One time event? Due to splitting, impact? Not
  real period change but NPA?

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19P/Borrelly

• Target of successful Deep Space 1 mission.
  Rotation period of 26 hours not precisely known
  (Mueller and Samarasinha 2002, Samarasinha and
  Mueller 2002)
• Work in progress Combine our data with other
  data to improve precision substantially
• Stay tuned for results at DPS 2007