Further investigation of changes in cometary rotation

Abstract

Samarasinha & Mueller (2013) related changes of cometary rotation to other physical parameters for four Jupiter family comets defining a parameter $X$, which is approximately constant within a factor of two irrespective of the active fraction of a comet. Two additional comets are added to this sample in this paper and the claim of a nearly constant parameter $X$ for these six comets is confirmed, albeit with a larger scatter. Taking the geometric mean of $X$ for all the comets above excluding 2P/Encke (as $X$ for each comet was determined with respect to that of 2P/Encke), the expected changes in the rotation periods for a sample of 24 periodic comets are derived. We identify comets from this sample that are most likely to show observationally detectable changes in their rotation periods. Using this sample and including the six comets used to determine $X$, we find a correlation between the parameter $\zeta$ (i.e. the total water production per unit surface area per orbit approximated by that inside of 4 au) and the perihelion distance $q$; specifically we derive $\zeta$ $\propto$ $q^{-0.8}$ and provide a theoretical basis for this in Appendix A. This relationship between $\zeta$ and $q$ enables ready comparisons of activity due to insolation between comets. Additionally, a relationship between the nuclear radius $R$ and the rotation period $P$ is found. Specifically, we find that on average smaller nuclei have smaller rotation periods compared to the rotation periods of larger nuclei. This is consistent with expectations for rotational evolution and spin-up of comet nuclei, providing strong observational evidence for sublimation-driven rotational changes in comets.

arXiv comment13 pages, 3 tables, 4 figures. Accepted by AJ

References in corpus (5)

• Beginning of activity in 67P/Churyumov-Gerasimenko and predictions for 2014/5
• Rotation of Cometary Nuclei: New Lightcurves and an Update of the Ensemble Properties of Jupiter-Family Comets
• A rapid decrease in the rotation rate of comet 41P/Tuttle-Giacobini-Kresák
• Relating Changes in Cometary Rotation to Activity: Current Status and Applications to Comet C/2012 S1 (ISON)
• The Rotation and Other Properties of Comet 49P/Arend-Rigaux, 1984 - 2012

Cited by in corpus (8)

• The Sublimative Evolution of (486958) Arrokoth
• A rapid decrease in the rotation rate of comet 41P/Tuttle-Giacobini-Kresák
• The Sublimative Torques of Jupiter Family Comets and Mass Wasting Events on Their Nuclei
• Systematics and Consequences of Comet Nucleus Outgassing Torques
• Comet 67P/Churyumov-Gerasimenko rotation changes derived from sublimation induced torques
• Properties of the Bare Nucleus of Comet 96P/Machholz 1
• Secular and Rotational Light Curves of 6478 Gault
• Non-Gravitational Forces and Spin Evolution of Comets