Eruptions of Coronal Jets in Numerical Simulations

Observations by Yohkoh, SOHO, Hinode and STEREO show that X-ray jets in the coronal holes, with an inverse-Y shape, occur at a rate of about 60 jets/day, and have a typical outward velocity of 160km/s, height of 50 Mm and width of 8 Mm, and liftime of 10 min (Savcheva et al., 2007). Numerical simulations suggest that jets are related to the reconnection between the newly emerging and pre-existing magnetic fields. We therefore here study the eruption of coronal jets by MHD simulations of flux emergence into the corona with ambient fields. To examine the role of the ambient fields, we carry out a set of simulations with fields of varying directions and strength. Reconnection of the emerging and ambient fields converts magnetic energy into thermal and kinetic energy of the plasma. The simulation results here captures the statistical properties of coronal jets, with temperature up to 2.5 MK, and speed up to 180 km/s. Heat conduction along the field lines and radiative cooling are also implemented to produce a more realistic thermal structure along the field lines, which allows us to compare the synthetic images with AIA observations.