Tail Morphology of Near-Sun Comet C/2020 F3 (NEOWISE)

We study the morphological changes of bright near-Sun comet C/2020 F3 (NEOWISE) using a series of multi-color wide-field images obtained in 2020 July 8–30, as the comet receded from 0.3 to 0.8 au from the Sun. Syndyne–synchrone modeling shows that the dusts that makes up the visible tail were mostly produced at and after perihelion. The images show changes of dust size distribution throughout the observations, with a gradual depletion of micron-sized particles. We discuss caveats in using the syndyne–synchrone model to study tail dynamics of comets at small perihelion distances. The r-band images consistently show a straight, non-dust tail throughout our observations that is likely to be made by neutral sodium atoms and H₂O⁺ molecules.