Dynamically Excited Rotational States of Comets

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Session 9 -- Solar System

[9.03] Dynamically Excited Rotational States of Comets

Nalin H. Samarasinha (NOAO)

Until recently, it was the normal practice to assume that a comet is in its dynamically stable, least energetic rotational state, corresponding to a pure rotation around the shortest axis of the nucleus.

Torques caused by localized sublimation (as observed in comet Halley) when numerically integrated over many orbits indicate that a cometary nucleus can evolve into different rotational states based on the shape of the nucleus and the nature and locations of the localized sublimation. One such scenario yields dynamically excited rotational states which are stable over many apparitions. Comparison with observations suggests that the rotation of comet Halley may indeed be in an excited but stable rotational state.

We will present the results which explain the different evolutionary paths of cometary rotational states and the relationship between the non-graviational forces caused by sublimation and changes in the orbital motion.

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