The influence of the size of ice–dust particles on the amplitude of the change in the brightness of a comet caused by an outburst

Abstract

ABSTRACT This paper presents a new approach to analysing the brightness change of a Jupiter family comet. We assume that the coma contains particles composed of water ice, carbonaceous, and silicate dust. Different sizes of dust particles were taken into account following the adopted size distribution. From an analysis of modern space missions, it is clear that the sizes of the dominant coma particles at the time of the outburst are in the order of micrometres to centimetres. However, most of these particles have dimensions that are comparable to the wavelength of electromagnetic radiation coming from the Sun. In the case of dust particles, four groups were distinguished depending on their dimensions. The performed calculations show that the particle size significantly influences the change of the cometary brightness, i.e. the scattering efficiency of the incident sunlight that occurs on the particle. The conducted numerical simulations show that the changes in the brightness of the comet oscillate approximately from −8 to −1 mag. This means that we can talk about outbursts, the amplitudes of which are most often observed.