Effects of the Solar Wind Conditions on Mercury's Exosphere: Hybrid Simulations
<pre class="western">We carry out a set of global hybrid simulations of the Mercury's magnetosphere with the interplanetary magnetic field oriented in the desired directions. <br />We study effects of changes of different solar wind parameters on the structure of the plasma circulation within Mercury&#8217;s magnetosphere. We focus our <br />study on the changes caused by changes in the orientation of the interplanetary magnetic field and the dynamic pressure (velocity) of the solar wind. <br />We study the structure of the of the Mercury&#8217;s magnetosphere under different solar wind conditions. Our primary focus is the assessment of the <br />precipitation levels of solar wind hydrogen on the Mercury's surface (the amount, the deposited energy, its spectra and angular distribution) and on the <br />formation of Mercury's exosphere. We examine density fluxes, energy levels and spectra of protons precipitating on Mercury&#8217;s surface as a function of <br />longitude and altitude. It has been established, that Mercury has a plasma belt formed by quasi-trapped solar wind plasma close to the Mercury&#8217;s surface. <br />Charged particles trapped in the belt mostly circle Mercury 1-2 times before they either precipitate on Mercury&#8217;s surface or escape into the Mercury&#8217;s <br />magnetospheric cavity. Lower dynamic pressure of the solar wind pushes magnetopause up above the Mercury&#8217;s surface and the plasma belt has more <br />space to develop. Its interaction with Mercury&#8217;s surface and dynamics under different solar wind conditions is essential on the precipitation of the plasma <br />on the Mercury&#8217;s surface. Higher dynamic pressure of the solar wind can push the bow shock towards Mercury&#8217;s surface and make the surface open to the <br />direct impact of the solar wind on the Mercury&#8217;s surface. Due to weak magnetic moment of the Mercury&#8217;s magnetosphere, the plasma environment at Mercury <br />is very dynamic.</pre>