We present 3D MHD simulations of the wind-wind interactions between a solar type star and a short period hot Jupiter exoplanet .
This is the first such simulation in which the stellar surface evolution is studied in detail .
In our simulations , a planetary outflow , based on models of FUV evaporation of the exoplanets upper atmosphere , results in the build-up of circumstellar and circumplanetary material which accretes onto the stellar surface in a form of coronal rain , in which the rain is HJ wind material falling onto the stellar surface .
We have conducted a suite of mixed geometry high resolution simulations which characterise the behaviour of interacting stellar and planetary wind material for a representative HJ hosting system .
Our results show that magnetic topology plays a central role in forming accretion streams between the star and HJ and that the nature of the accretion is variable both in location and in rate , with the final accretion point occurring at \phi~ { } = ~ { } 227 ^ { \circ } ahead of the sub-planetary point and \theta~ { } = ~ { } 53 ^ { \circ } below the orbital plain .
The size of the accretion spot itself has been found to vary with a period of 67 \mathrm { ks } .
Within the accretion spot , there is a small decrease in temperature accompanied by an increase in density compared with ambient surface conditions .
We also demonstrate that magnetic fields can not be ignored as accretion is highly dependent upon the magnetic topology of both the HJ and the host .
We characterise this behaviour as Star Planet Wind Interaction ( SPWI ) .