Tomography of the Solar Corona with the Wide-Field Imager for the Parker Solar Probe

Abstract

The Wide-field Imager for the Parker Solar Probe (PSP/WISPR) comprises two telescopes that record white-light total brightness $[B]$ images of the solar corona. Their fields of view cover a widely changing range of heliocentric heights over the 24 highly eccentric orbits planned for the mission. In this work, the capability of PSP/WISPR data to carry out tomographic reconstructions of the three-dimensional (3D) distribution of the coronal electron density is investigated. Based on the precise orbital information of the mission, $B$-images for Orbits 1, 12, and 24 are synthesized from a 3D magnetohydrodynamic model of the corona. For each orbit, the time series of synthetic images is used to carry out a tomographic reconstruction of the coronal electron density and results are compared with the model. As the PSP perihelion decreases, the range of heights that can be tomographically reconstructed progressively shifts to lower values, and the period required to gather the data decreases. For Orbit 1 tomographic reconstruction is not possible. For Orbit 12, tomographic reconstruction is possible in the heliocentric height range ${\approx}\, 5\,\mbox{--}\,15~\mathrm{{R}_{\odot}}$, over a region spanning up to ${\approx}\,160^{\circ}$ in Carrington longitude, with data gathered over a ${\approx}\, 3.4$ day-long period. For Orbit 24, tomographic reconstruction is possible in the heliocentric height range ${\approx}\,3\,\mbox{--}\,10~\mathrm {R}_{\odot}$, over a region spanning up to ${\approx} \,170^{\circ}$ in Carrington longitude, with data gathered over a ${\approx}\, 2.8$ day-long period.