Characterizing the Activity of Manx Comets
Abstract
We will report on an investigation of the physical characteristics of several Manx comets to understand their origins, evolution, and roles in solar system growth. Manx comets are long period comets with little to no activity driven by sublimation. Characterizing these comets' activity and composition allows us to assess the fraction of rocky inner solar system material that has been ejected to the Oort Cloud and is now migrating in to the inner solar system. This helps us distinguish between solar system formation models. We characterize each comet's physical properties and investigate potential ice sublimation using several methods including analysis of dust and coma dynamics with composite images, quantifying changes in photometry with sublimation and thermal models, and calculating spectral reflectivity to determine surface material composition and likely asteroid class. Most recently, we have characterized the activity and physical properties of Manx comets C/2016 VZ18 and C/2016 EF9 with an ensemble of professional and amateur astronomy data. These comets were dormant up to ~1 au and then exhibited significant brightening close to perihelion that is atypical of surface ice sublimation. WISE observations show that their activity is likely driven by CO2, and we use deep stacked images to assess the nucleus sizes to be less than 1km. Assuming the volatiles exist at a depth, we developed and improved thermal models to characterize the heat transport to the interior. We verified these models to match the temperature profiles seen on the Rosetta mission, and adopted a material strength and crust depth to be 100 Pa and 10 cm based on literature values. Our models calculate the volatile production rate and implement the removal of a dust crust after exceeding a critical pressure in the interior. We calculate the depth and thickness of the ice to be 0.4 m and 0.15 m respectively. This is a model we will continue to update and implement for future long period comets.
- Publication:
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American Astronomical Society Meeting Abstracts #235
- Pub Date:
- January 2020
- Bibcode:
- 2020AAS...23522607B