Particle kinetic analysis of a polar jet from SECCHI COR data

TL;DR

This study models a polar jet observed by SECCHI on STEREO, using kinetic particle simulations to analyze brightness evolution, estimate launch timing, initial velocities, and mass, providing insights into jet dynamics and source region conditions.

Contribution

It introduces a kinetic particle model to interpret coronagraph observations of a polar jet, estimating launch time, velocity distribution, and mass, with a focus on gravity as the dominant force.

Findings

Kinetic model accurately explains brightness evolution.

Initial velocity distribution deviates from Maxwellian at high energies.

Estimated jet mass and electron density are consistent with lower corona conditions.

Abstract

Aims. We analyze coronagraph observations of a polar jet observed by the Sun Earth Connection Coronal and Heliospheric Investigation (SECCHI) instrument suite onboard the Solar TErrestrial RElations Observatory (STEREO) spacecraft. Methods. In our analysis we compare the brightness distribution of the jet in white-light coronagraph images with a dedicated kinetic particle model. We obtain a consistent estimate of the time that the jet was launched from the solar surface and an approximate initial velocity distribution in the jet source. The method also allows us to check the consistency of the kinetic model. In this first application, we consider only gravity as the dominant force on the jet particles along the magnetic field. Results. We find that the kinetic model explains the observed brightness evolution well. The derived initiation time is consistent with the jet observations by the EUVI telescope at various wavelengths. The initial particle velocity distribution is fitted by Maxwellian distributions and we find deviations of the high energy tail from the Maxwellian distributions. We estimate the jet's total electron content to have a mass between 3.2 \times 1014 and 1.8 \times 1015 g. Mapping the integrated particle number along the jet trajectory to its source region and assuming a typical source region size, we obtain an initial electron density between 8 \times 109 and 5 \times 1010 cm-3 that is characteristic for the lower corona or the upper chromosphere. The total kinetic energy of all particles in the jet source region amounts from 2.1 \times 1028 to 2.4 \times 1029 erg.