Parker Solar Probe Enters the Magnetically Dominated Solar Corona

J C Kasper; K G Klein; E Lichko; Jia Huang; C H K Chen; S T Badman; J Bonnell; P L Whittlesey; R Livi; D Larson; M Pulupa; A Rahmati; D Stansby; K E Korreck; M Stevens; A W Case; S D Bale; M Maksimovic; M Moncuquet; K Goetz; J S Halekas; D Malaspina; Nour E Raouafi; A Szabo; R MacDowall; Marco Velli; Thierry Dudok de Wit; G P Zank

doi:10.1103/PhysRevLett.127.255101

Parker Solar Probe Enters the Magnetically Dominated Solar Corona

Phys Rev Lett. 2021 Dec 17;127(25):255101. doi: 10.1103/PhysRevLett.127.255101.

Authors

J C Kasper¹, K G Klein², E Lichko², Jia Huang³, C H K Chen⁴, S T Badman⁵, J Bonnell⁵, P L Whittlesey⁵, R Livi⁵, D Larson⁵, M Pulupa⁵, A Rahmati⁵, D Stansby⁶, K E Korreck⁷, M Stevens⁷, A W Case⁷, S D Bale⁸, M Maksimovic⁹, M Moncuquet⁹, K Goetz¹⁰, J S Halekas¹¹, D Malaspina¹², Nour E Raouafi¹³, A Szabo¹⁴, R MacDowall¹⁴, Marco Velli¹⁵, Thierry Dudok de Wit¹⁶, G P Zank¹⁷

Affiliations

¹ BWX Technologies, Inc., Washington, DC 20001, USA and Climate and Space Sciences and Engineering, University of Michigan, Ann Arbor, Michigan 48109, USA.
² Lunar and Planetary Laboratory, University of Arizona, Tucson, Arizona 85719, USA.
³ Climate and Space Sciences and Engineering, University of Michigan, Ann Arbor, Michigan 48109, USA.
⁴ Department of Physics and Astronomy, Queen Mary University of London, London E1 4NS, United Kingdom.
⁵ Space Sciences Laboratory at University of California, Berkeley, California, USA.
⁶ Mullard Space Science Laboratory, University College London, Holmbury St. Mary, Surrey RH5 6NT, United Kingdom.
⁷ Smithsonian Astrophysical Observatory, Cambridge, Massachusetts 02138, USA.
⁸ Physics Department, University of California, Berkeley, California 94720-7300, USA and Space Sciences Laboratory at University of California, Berkeley, California 94720-7300, USA.
⁹ LESIA, Observatoire de Paris, Universite PSL, CNRS, Sorbonne Universite, Universite de Paris, 5 place Jules Janssen, 92195 Meudon, France.
¹⁰ School of Physics and Astronomy, University of Minnesota, Minneapolis, Minnesota 55455, USA.
¹¹ Department of Physics and Astronomy, University of Iowa, Iowa City, Iowa 52242, USA.
¹² Laboratory for Atmospheric and Space Physics, University of Colorado Boulder, Boulder, Colorado 80303, USA.
¹³ The Johns Hopkins Applied Physics Laboratory, Laurel, Maryland 20723, USA.
¹⁴ Heliospheric Physics Laboratory, NASA Goddard Space Flight Center, Greenbelt, Maryland, 20771, USA.
¹⁵ Earth Planetary and Space Sciences, UCLA, California 90095, USA.
¹⁶ LPC2E, CNRS and University of Orléans, Orléans, France.
¹⁷ Department of Space Science and Center for Space Plasma and Aeronomic Research, University of Alabama in Huntsville, Huntsville, Alabama 35805, USA.

PMID: 35029449
DOI: 10.1103/PhysRevLett.127.255101

Abstract

The high temperatures and strong magnetic fields of the solar corona form streams of solar wind that expand through the Solar System into interstellar space. At 09:33 UT on 28 April 2021 Parker Solar Probe entered the magnetized atmosphere of the Sun 13 million km above the photosphere, crossing below the Alfvén critical surface for five hours into plasma in casual contact with the Sun with an Alfvén Mach number of 0.79 and magnetic pressure dominating both ion and electron pressure. The spectrum of turbulence below the Alfvén critical surface is reported. Magnetic mapping suggests the region was a steady flow emerging on rapidly expanding coronal magnetic field lines lying above a pseudostreamer. The sub-Alfvénic nature of the flow may be due to suppressed magnetic reconnection at the base of the pseudostreamer, as evidenced by unusually low densities in this region and the magnetic mapping.