A POSSIBLE DISCONNECTION EVENT IN THE INNER COMA OF COMET BRADFIELD 1979X

High-resolution photographs of the long-period comet Bradfield 1979X t aken in blue as well as in red light were digitized and morphologicall y analysed. The photographs were taken with the ESO 3.6-m Telescope at La Silla, Chile, on 23 and 24 January 1980, when the comet had a geoc entric distance of Delta = 0.2 AU. They are therefore among the most h ighly resolved observations ever-obtained of a cometary coma. A change in the appearance of the plasma tail pear the nucleus between 23 and 24 January 1980 can clearly be observed. We interpret this distortion as the result of a possible disconnection event (DE). The starting tim e of the DE has been determined to 23 January 1980, between 4:00 UT an d 5:00 UT. The solar wind and interplanetary magnetic field properties for January 1980 were investigated to search for a possible associati on of the DE to Variations in the solar wind velocity and in the inter planetary magnetic field (IMF). The solar wind velocity remained fairl y constant and pretty low during,the time relevant for the DE. Althoug h the evidence is not unambiguous, a slight possibility for an associa tion to a variation in the IMF has been found. In addition to the DE, the structural enhanced images show indications for an enhanced abunda nce of gas and dust particles in sunward direction which could be the result of an asymmetric outgassing from the nucleus.