Dynamics of the charged particles released from a Sun-grazing comet in the solar corona

The sun-grazing comet C/2011 W3(Lovejoy)showed a distorted,unconventional tail morphology near its perihelion(1.2Rs).Based on the“Solar Corona and Inner Heliosphere”modeling result of the magnetic field and plasma dynamics in the solar corona,we use the Runge-Kutta method to simulate the moving trajectory of charged dust and ion particles released at different positions from the C/2011 W3 orbit.We find that the dust particles near the sun,which are subject to a strong magnetic Lorentz force,travel differently from their counterparts distant from the sun,where the latter are mainly affected by the solar gravitational force and radiation pressure.According to the simulation results,we propose that the magnetic mirror effect can rebound the charged dust particles back away from the sun and be regarded as one crucial cause of the dust-free zone formation.We find that ions mainly move along magnetic field lines at an acute angle to the comet's direction of motion.The cometary ions'movement direction was determined by the comet's velocity and the coronal magnetic field,which are responsible for the C/2011 W3’s unique comet tail shape near perihelion.Additionally,the ion particles also experience perpendicular drift motion,mainly dominated by the electric field drift,which is similar to and can be used to approximate the solar wind's transverse velocity at its source region.

Highlight Advances in Planetary Physics in the Solar System: In Situ Detection Over the Past 20 Years

Planetary science is the science of studying planets,moons,and planetary systems.The scale of the research objects ranges from small meteoroids to large gas giant planets,and the research purpose is to determine their composition,dynamics,formation,evolution,mutual relationship,and history.With the development of human space technology,planetary exploration has become one of the most important space exploration activities of mankind.According to statistics from the Spacecraft Encyclopedia website,as of December 2021,a total of 252 planetary probes have been launched around the world.The missions reveal the deep space to humankind.In this paper,we review some advances in planetary science made by these missions in the past years.The topics involve interior structures,geological features,atmospheres,magnetospheres,and so on,not every aspect but as much as possible.Although there are still many extraordinary scientific results that have not been included,we believe that this review can already help people learn about the scientific results of planetary exploration and hopefully inspire the next generation of planetary missions.