Color differences within the dust tail of C/2024 G3 (ATLAS)

Abstract The dust tail of a comet is composed of dust particles with sizes ranging from microns to sub-microns, and appears white in photographs due to reflected light caused by Mie scattering of sunlight. However, due to the dramatic improvement of imaging and image processing technology in recent years, subtle color differences have become visible. The dust tail of C/2024 G3 (ATLAS) was branched into multiple parts, and the color appeared to be different locally. Most of the dust tail branches were synchronic bands along synchrones that indicate the periodicity of cometary activity, but the branches along syndynes, which are distributed when dust with a ratio of solar radiation pressure to gravity $\beta$ = 0.7–0.8 is continuously released, appear to be different in color from the other branches. We confirmed that these color differences probably really exist by measuring the red and blue signal intensity of the color image along each syndyne and comparing them between syndynes. This slight color difference is seen as the color of the dust tail by being emphasized by image processing, but we also considered the reasons why this slight difference occurs. The areas where the color differences were observed were areas where striae were occurring due to the fragmentation of dust particles, so we concluded that the color differences likely reflect changes in the properties of the dust particles due to fragmentation.