Resumen
Cometary and solar wind data are compared with the purpose of identifying the solar wind conditions which are associated with comet plasma tail disconnection events (DEs). The cometary data are from The International Halley Watch Atlas of Large-Scale Phenomena (Brandt et al. 1992). A systematic visual analysis of the atlas images (Voelzke & Matsuura, P&SS 46, 835, 1998) revealed, among other morphological structures, 47 DEs along the plasma tail of comet P/Halley. The solar wind data are in situ measurements from IMP-8 (King, IMS Source Book p10, 1982), which are used to construct the actual variation of solar wind speed, density and dynamic pressure during the analysed intervals. This work compares the onsets of these DEs with the solar wind dynamic pressure variations in order to clarify if pressure effects play an important role in the formation of DEs and if they can even be considered as the triggering mechanism. The analysis however reveals a poor correlation (23%) between the onsets of P/Halley´s DEs and the associated pressure effects. This result is in good agreement with Wegmann (A&A 294, 601, 1995) who concluded in an independent and theoretical analysis, that about 25% of all tail disconnections must be caused by interplanetary shocks. The DEs onsets of comet P/Halley analysed in this work, calculated from observational data, do not corroborate the idea that DEs are associated with dynamic pressure effects.
