I. L. Lai (Institute of Space Science, National Central University);W. H. Ip( Institute of Astronomy, National Central University)
Rosetta spacecraft observations at close distance have shown many interesting phenomenon on comet 67P/ Churyumov–Gerasimenko. The OSIRIS imaging observations shows that the dust coma was filled by numerous dust jets emanating from the nucleus surface. Gas outflow could drag dust grains as indicated by the colliminated dust jet structures on the sunlit side because of the diurnal thermal cycle and the irregular shape of the nucleus. This means that they can be used to trace the gas sublimation regions as the comet moved around the perihelion. In this work, we show the sources of dust jets would move in consonance with the sunlit belt. Therefore, a number of source regions characterized by repeated jet activity could be identified which might be the result of local topographical variations or chemical heterogeneities. We found that some jet sources could be turned on or off in short time intervals because of the highly irregular topography of the nucleus surface. With a time variability model of the global gas production rate, we also investigate the transport of dust grains calculated by dust particles dynamics under the influences of the rotating nucleus and gas dragging force. From these considerations, we find a deposition of the ejected dust from the Southern hemisphere to the Northern hemisphere during the southern summer season.