Planetary and exoplanetary Astronomy Lunch Seminar (PALS) for 2022-11-14

Series: Planetary and exoplanetary Astronomy Lunch Seminar (PALS)
Date: Monday 14-November-2022
Time: 11:15-12:15
Location: ATL 1250 and Zoom (contact for link)
Speaker: Qasim Afghan
Title: Structural Analysis of Long Period Comet Dust Tails using the Finson-Probstein Model

Abstract: Long period comets (LPCs), originating from the Oort Cloud, are highly unprocessed bodies that provide insight into the conditions present in the early Solar System. By analysing comet dust tails, characteristics of the parent comet body and the heliospheric conditions it experiences during its perihelion passage can be ascertained. Using images taken by the amateur astronomer community, these dust tails are analysed using the Finson-Probstein model. This modelled dust tail structure is then projected and overlaid onto the comet image to directly compare and identify similarities and discrepancies between the model and the image. Using the novel analysis method of mapping the image onto dust grain beta vs ejection time parameter space[1], tail structures can be more easily identified, analysed and tracked over time. This talk will focus on two specific comets, C/2020 F3 (NEOWISE) and C/2014 Q1 (PanSTARRS). Comet NEOWISE (C/2020 F3) displayed a highly structured dust tail, exhibiting the most prominent dust tail features visible from Earth since Comet McNaught (C/2006 P1) in the Southern Hemisphere and Comet Hale-Bopp (C/1995 O1) in the Northern Hemisphere. Fine-scale dust tail structures are identified and characterised to create a ‘profile’ of the comet’s dust tail. This is then compared with similar structures seen in other cometary dust tails, providing explanations on how these structures form and the shared characteristics of LPCs as a population. The first identification of a ‘dust tail gap’, a region of low dust number density, was identified in amateur images of the dust tail of long period comet C/2014 Q1 (PanSTARRS) . This gap presented itself as a wedge-shaped region devoid of dust in the middle of the dust tail. This dust-sparse area corresponds to the comet’s perihelion, when the comet should be at its most active. This dust tail ‘gap’ is analysed and parameterized, and the results used to investigate the origins of this peculiar structure.

[1] Price, Oliver, Geraint H. Jones, Jeff Morrill, Mathew Owens, Karl Battams, Huw Morgan, Miloslav Drückmuller, and Sebastian Deiries. 2019. "Fine-Scale Structure In Cometary Dust Tails I: Analysis Of Striae In Comet C/2006 P1 (Mcnaught) Through Temporal Mapping". Icarus 319: 540-557. doi:10.1016/j.icarus.2018.09.013.

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