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arXiv · 2109.02039

Coma morphology and dust emission pattern of comet C/2020 F3 (NEOWISE)

F. Manzini·V. Oldani·P. Ochner·E. Barbotin·L. R. Bedin·R. Behrend·G. Fardelli
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Abstract

The recent close approach of comet C/2020 F3 (NEOWISE) allowed us to study the morphology of its inner coma. From the measurement of the dust ejection velocityon spiral structures expanding around the nucleus, we estimated a mean deprojectedexpansion velocity Vd= 1.11+/-0.08 km s^-1. Assuming that a new shell formed after every rotation of the comet, a rotation period of 7.8+/-0.2 hours was derived. The spin axis orientation was estimated at RA 210+/-10d, Dec. +3+/-10d. The comamorphology appears related to two strong, diametrically opposite emissions located at mid-latitudes on the nucleus. A qualitative modelling of the coma produced consistent results with a wide range of dust sizes (0.80 to 800 micro-m), with inversely correlated densities (0.003 to 3.0 g cm^-3). Images taken with Vj and r-Sloan filters showed a greater concentration of dust in the first two shells, and an increasing density of radicals emitting in the B and V band-passes from the third shell outwards. Striae-like structures in the tail suggest that dust particles have different sizes.

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F. Manzini, V. Oldani, P. Ochner, E. Barbotin, L. R. Bedin, R. Behrend, G. Fardelli. 2021-09-05. Coma morphology and dust emission pattern of comet C/2020 F3 (NEOWISE). https://doi.org/10.1093/mnras/stab1849

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