SH032-01
Electron Heat Flux in the Near-Sun Environment

Friday, 11 December 2020: 10:30
Virtual
Jasper S Halekas1, Phyllis L Whittlesey2, Davin E Larson3, Daniel McGinnis4, Stuart D Bale5, Matthieu Berthomier6, Anthony W Case7, Benjamin D G Chandran8, Justin Christophe Kasper9, Kristopher G. Klein10, Kelly E Korreck7, Roberto Livi2, Robert J MacDowall11, Milan Maksimovic12, David Malaspina13, Lorenzo Matteini14, Marc Pulupa2 and Michael Louis Stevens7, (1)University of Iowa, Department of Physics and Astronomy, Iowa City, IA, United States, (2)Space Sciences Laboratory, University of California Berkeley, Berkeley, CA, United States, (3)Space Sciences Laboratory, Berkeley, CA, United States, (4)University of Iowa, Iowa City, IA, United States, (5)University of California Berkeley, Space Sciences Laboratory, Berkeley, CA, United States, (6)LPP, Ecole Polytechnique, UPMC, Paris, France, (7)Smithsonian Astrophysical Observatory, Cambridge, MA, United States, (8)University of New Hampshire, Durham, NH, United States, (9)University of Michigan, Climate and Space Sciences and Engineering, Ann Arbor, MI, United States, (10)University of Arizona, Lunar and Planetary Laboratory, Tucson, AZ, United States, (11)NASA/Goddard Space Flight Center, Greenbelt, United States, (12)LESIA, Observatoire de Paris, Université PSL, CNRS, Sorbonne Université, Université de Paris, Meudon, France, (13)University of Colorado, Astrophysical and Planetary Sciences Department, Boulder, CO, United States, (14)LESIA, OBSPM, Paris, France
Recorded Presentation
Abstract:
We survey the electron heat flux observed by the Parker Solar Probe (PSP) in the near-Sun environment at heliocentric distances of 0.125-0.25 AU. We utilize measurements from the Solar Wind Electrons Alphas and Protons and FIELDS experiments to compute the solar wind electron heat flux and its components and to place these in context. PSP observations reveal that electron heat flux signatures near the Sun have a close correspondence with plasma beta, consistent with regulation by collisionless mechanisms. The magnitude of the heat flux is anticorrelated with solar wind speed, as a result of the lower saturation heat flux in the higher-speed wind. The net heat flux decreases in high-beta regions in the vicinity of the heliospheric current sheet, but in most such cases the omnidirectional suprathermal electron flux remains at a comparable level or even increases, seemingly inconsistent with disconnection from the Sun. The measured heat flux values appear inconsistent with regulation primarily by collisional mechanisms near the Sun. Instead, the observed heat flux dependence on plasma beta and the distribution of suprathermal electron parameters are both consistent with theoretical instability thresholds associated with oblique whistler/magnetosonic modes.
Previous Abstract | Next Abstract >>