Dix Planetary Science Seminar

In this talk, I will talk about cometary fragmentation in general as well as a case study of split comet 73P/Schwassmann-Wachmann 3. Fragmentation mechanisms remain somewhat mysterious with potential mechanisms including include tidal forces, rotational instability, thermal pressure, outgassing pressure, and impacts. Comet 73P has been observed to fragment on several occasions, however the cause of its fragmentation is poorly understood. We analyzed unpublished archival Hubble Space Telescope data in order to understand its fragmentation mechanism. For example, the literature presents a wide range of measured rotational periods for the nucleus of the comet, 73P-C, some that suggest the nucleus might have split due to rotational instability. However, we find the most likely value of the rotation period to be ~10.4 hours, much longer than the critical period for rotational instability for any reasonable nucleus density. I will also present our current work on fragments 73P-B and G, which show 10s to 100s of fragments within their comae. We will analyze the relative motion of these fragments in order to determine their speed and acceleration on the plane of the sky. This will allow us to conclude whether the fragmentation process was staggered over time or impulsive. From this work, we rule out rotational instability as potential breakup mechanism for 73P and provide a deeper analysis of its fragmentation evolution