The Study With The Distribution Of Water Ice Sublimation On Short Period Comet Surface

Comets are the primitive planetesimals left in the solar system.Studying the evolution of comet nucleus is of great significance for us to understand how solar system bodies formatted and evolved.After absorbing the energy from solar radiation,the volatile components of comets will sublimate and drive the dust movement,resulting in the material loss of comet nucleus.Therefore,the activity of comet nucleus affects the surface morphology and even the overall shape evolution.The orbit data were obtained from IAU(International Astronomical Union)MPC(Minor Planet Center).The spin and precession of comet nucleus were taken into account.The Mass loss-driven Shape Evolution Model(MONET)was used to simulate the short-period comets.The distribution of solar radiation and surface erosion depth in one orbital period of short-period comets 1P/Halley,9P/Tempel 1,19P/Borrelly,67P/C-G(Churyumov-Gerasimenko),81P/Wild 2 and 103P/Hartley 2 is calculated.The results show that the erosion depth of the northern and southern hemispheres is asymmetrical.The fundamental reason for this phenomenon lies in the nonlinear relationship among solar incident energy,orbital variation and water molecular productivity.For orbits with high eccentricity,the water molecular productivity of comet nuclei near perihelion and aphelion is significantly different and accumulates over time.For a comet with a large spin axis inclination,the hemisphere directly radiated by the sun near the perihelion will be eroded more than the aphelion.Considering latitude of direct sunlight point,this paper discussed the influence of comet rotation,orbit and precession to the active range of direct sunlight point,and then discussed the impact on its distribution of surface water ice sublimation.The possible reason of differences in erosion is also discussed,which explains the results of the numerical simulation in theory.This paper also compares the differences about distribution of erosion depth between Jupiter-family Comets and Halley-type Comets,and among Jupiter-family Comets.The results show that the comet’s semi-major axis determines the order of magnitudes of water ice erosion depth.The rotation and precession of the comet nucleus determines the distribution of water ice erosion depth.Finally,a new model of comet nucleus with heterogeneous material distribution,including heat conduction process and the recoil effect of gas injection on comet nucleus,will be the future research direction of this work.These improvements will give more real and detailed calculations.