Breakdown of Dust from Near-Sun Comet C/2020 F3 (NEOWISE)

Near-Sun comet C/2020 F3 (NEOWISE) approached the Sun to q=0.29 au on 2020 July 3 and subsequently became the brightest comet observable under dark skies in over a decade. We obtained high spatial resolution optical color and polarization observations with the Hubble Space Telescope (HST) on 2020 August 8 while the comet was at r=0.98 au from the Sun, Δ=0.97 au from Earth, and α=63° phase angle. These observations revealed the presence of reddened and highly polarized dust jets, as well as a general trend of decreasing dust redness and polarization away from the nucleus that likely resulted from the physical and/or chemical breakdown of dust grains under solar radiation. We connect these results to photometry, polarimetry, and spectroscopy from ground-based observations in 2020 July-August and from the SOHO LASCO C3 coronagraph in 2020 June to explore differences in the rate and nature of cometary dust breakdown processes near and away from the Sun.