Coma morphology and dust emission pattern of comet C/2020 F3 (NEOWISE)
Date Issued
2021
Author(s)
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 velocity on spiral structures expanding around the nucleus, we estimated a mean deprojected expansion velocity Vd = 1.11 ± 0.08 km s-1. Assuming that a new shell formed after every rotation of the comet, a period of 7.8 ± 0.2 h was derived. The spin axis orientation was estimated at RA 210° ± 10°, Dec. +35° ± 10°. The coma morphology 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 (0.80-800 μm), with inversely correlated densities (0.003-3.0 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.
Volume
506
Issue
4
Start page
6195
Issn Identifier
0035-8711
Ads BibCode
2021MNRAS.506.6195M
Rights
open.access
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