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Authors: Szabo Adam, Larson Davin, Whittlesey Phyllis, Stevens Michael L., Lavraud Benoit, et al.
Title: The Heliospheric Current Sheet in the Inner Heliosphere Observed by the Parker Solar Probe

The Parker Solar Probe (PSP) completed its first solar encounter in 2018 November, bringing it closer to the Sun than any previous mission. This allowed in situ investigation of the heliospheric current sheet (HCS) inside the orbit of Venus. The Parker observations reveal a well defined magnetic sector structure placing the spacecraft in a negative polarity region for most of the encounter. The observed current sheet crossings are compared to the predictions of both potential field source surface and magnetohydrodynamic models. All the model predictions are in good qualitative agreement with the observed crossings of the HCS. The models also generally agree that the HCS was nearly parallel with the solar equator during the inbound leg of the encounter and more significantly inclined dur. . .
Date: 02/2020 Publisher: The Astrophysical Journal Supplement Series Pages: 47 DOI: 10.3847/1538-4365/ab5dac Available at:
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Authors: Riley Pete, Downs Cooper, Linker Jon A., Mikic Zoran, Lionello Roberto, et al.
Title: Predicting the Structure of the Solar Corona and Inner Heliosphere during Parker Solar Probe 's First Perihelion Pass

NASA’s Parker Solar Probe (PSP) spacecraft reached its first perihelion of 35.7 solar radii on 2018 November 5. To aid in mission planning, and in anticipation of the unprecedented measurements to be returned, in late October, we developed a three-dimensional magnetohydrodynamic (MHD) solution for the solar corona and inner heliosphere, driven by the then available observations of the Sun’s photospheric magnetic field. Our model incorporates a wave-turbulence-driven model to heat the corona. Here, we present our predictions for the structure of the solar corona and the likely in situ measurements that PSP will be returning over the next few months. We infer that, in the days prior to first encounter, PSP was immersed in wind emanating from a well-established, positive-polarity north. . .
Date: 04/2019 Publisher: The Astrophysical Journal Pages: L15 DOI: 10.3847/2041-8213/ab0ec3 Available at:
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Authors: Lamy Philippe, Floyd Olivier, Mikic Zoran, and Riley Pete
Title: Validation of MHD Model Predictions of the Corona with LASCO-C2 Polarized Brightness Images

Progress in our understanding of the solar corona requires that the results of advanced magnetohydrodynamic models driven by measured magnetic fields, and particularly the underlying heating models, be thoroughly compared with coronal observations. The comparison has so far mainly concerned the global morphology of the corona, synthetic images calculated from the models being compared with observed images. We go one step further by performing detailed quantitative comparisons between the calculated polarized radiance p B using the three-dimensional electron density produced by MHD models and well calibrated polarized images obtained by the Large Angle Spectrometric Coronagraph LASCO-C2 coronagraph complemented by ground-based images when available from the Mauna Loa Solar Observatory Ma. . .
Date: 11/2019 Publisher: Solar Physics DOI: 10.1007/s11207-019-1549-9 Available at:
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Authors: de Patoul Judith, Foullon Claire, and Riley Pete

Knowledge of the electron density distribution in the solar corona put constraints on the magnetic field configurations for coronal modeling and on initial conditions for solar wind modeling. We work with polarized SOHO/LASCO-C2 images from the last two recent minima of solar activity (1996-1997 and 2008-2010), devoid of coronal mass ejections. The goals are to derive the 4D electron density distributions in the corona by applying a newly developed time-dependent tomographic reconstruction method and to compare the results between the two solar minima and with two magnetohydrodynamic models. First, we confirm that the values of the density distribution in thermodynamic models are more realistic than in polytropic ones. The tomography provides more accurate distributions in the polar reg. . .
Date: 11/2015 Publisher: The Astrophysical Journal Pages: 68 DOI: 10.1088/0004-637X/814/1/68 Available at:
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