An analysis of intensity profile of the solar energetic particles at the maximum of the 24th solar cycle on August 9, 2011

Abstract

Our Sun releases large amount of coronal matter into outer space due to violent eruption known as solar flare. This phenomenon has large impact on Earth by disrupting radio communication on satellites. It happens every solar cycle corresponding to change in Sun’s activity every periodic 11 year with varying number of sunspots on its surface.

In this research we study the behavior of solar energetic particle at the maximum of 24th solar cycle on August 9, 2011. The X-ray class of the selected solar event is X6.9 with solar flare position on the Sun as N18W68 and solar wind speed of 551.5 kms-1. The chosen element were He, C, N, O and Fe which are the elements having lower mass, medium mass and higher mass. The kp index for our event of interest was equal to 3 which indicated that it did not have much effect to earths magnetic field due to solar flare.

We collect data of an event from the SIS (Solar Isotope Spectrometer) instrument on ACE spacecraft (Advanced Composition Explorer). The data are then simulated for the motion of particles from the solar flare using transport equation of Ruffolo (1995, 1998) solved by numerical technique of finite different method in C++ program. Mean free path and injection time are obtained for particles that propagate from Sun to Earth by using compared fitting method of piecewise linear function between the data collected from spacecraft and simulation results. We determine the best piecewise linear injection function and chi square value for each mean free path. Chi square is defined as the difference between data from simulation result and data from spacecraft. We then, work out the injection time duration by the means of method called full width at half maximum of the injection function.

We found out that most particles with higher energy level propagated from Sun to Earth faster than particles with lower energy levels due to their higher speed. The trend of mean free path is found to be roughly constant for each event. The calculated approximate injection time for our event was between 30 – 60 min for each element which is very close to injection time as detected from Sun directly. Thus, we concluded that our solar event of interest didn’t had much effect from the space environment.

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