Drs Beatrice Mueller and Nalin Samarasinha will pursue a research project to determine the complete spin state of the well observed Jupiter family comet 10P/Tempel 2 combining their existing data taken at different observing geometries. They will confirm (or refute) the period change of this comet observed by Mueller and Ferrin. If the period change is confirmed, they will determine if comet 10P/Tempel 2 is spinning up or down. Mueller and Ferrin were not able to determine the sense of the period change. That comets should evolve rotationally is in theory not disputed, but models are not constrained due to the lack of observations. The measuring of changes in rotational periods has profound implications for understanding the influence of activity on the rotational state and on the eventual spin states of comets, the interior structure of cometary nuclei, their rigidity, and the efficiency of damping of mechanical energy. The interior structure of cometary nuclei is ultimately related to the formation and evolution of comets. This research by Drs Mueller and Samarasinha will add a complete spin state for a Jupiter family comet to the small existing data base of only a few spin states.
Drs Mueller and Samarasinha will also investigate using a numerical light curve program if the period change in comet 10P/Tempel 2 is not due to an actual change in rotational period but rather due to the comet being in a slightly more energetic non-principal axis spin state. Most comets are expected to be in a non-principal axis spin state but that is not what is observed. There are two reasons for this discrepancy: (a) light curve observations are not accurate enough to detect slightly excited spin states and/or (b) the damping times and/or excitation times are incorrect.
Drs Mueller and Samarasinha will mentor an undergraduate student with a focused project related to the above research that can be completed during the summer providing the student with experience in every aspect of this research. Drs Mueller and Samarasinha will submit images and photometry of comet 10P/Tempel 2 to the Small Bodies Node of the Planetary Data System, which gives access to the entire astronomical community. Their data can be combined with earlier and future data which will increase the science return beyond their results. ***
