Academic Journal
Suprathermal ion energy spectra and anisotropies near the heliospheric current sheet crossing observed by the Parker Solar Probe during encounter 7
| العنوان: | Suprathermal ion energy spectra and anisotropies near the heliospheric current sheet crossing observed by the Parker Solar Probe during encounter 7 |
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| المؤلفون: | Desai, M, Mitchell, DG, McComas, DJ, Drake, JF, Phan, T, Szalay, JR, Roelof, EC, Giacalone, J, Hill, ME, Christian, ER, Schwadron, NA, McNutt, RL, Wiedenbeck, ME, Joyce, C, Cohen, CMS, Davis, AJ, Krimigis, SM, Leske, RA, Matthaeus, WH, Malandraki, O, Mewaldt, RA, Labrador, A, Stone, EC, Bale, SD, Verniero, J, Rahmati, A, Whittlesey, P, Livi, R, Larson, D, Pulupa, M, MacDowall, RJ, Niehof, JT, Kasper, JC, Horbury, TS |
| المساهمون: | Science and Technology Facilities Council (STFC) |
| المصدر: | 12 ; 1 |
| بيانات النشر: | American Astronomical Society |
| سنة النشر: | 2021 |
| المجموعة: | Imperial College London: Spiral |
| مصطلحات موضوعية: | Science & Technology, Physical Sciences, Astronomy & Astrophysics, MAGNETIC RECONNECTION, EARTHS MAGNETOPAUSE, CHARGE STATES, INTERPLANETARY SHOCKS, ACCELERATION, COMPTON, PROTON, COEFFICIENTS, SWITCHBACKS, PROPAGATION, astro-ph.SR, physics.space-ph, 0201 Astronomical and Space Sciences, 0202 Atomic, Molecular, Nuclear, Particle and Plasma Physics, 0306 Physical Chemistry (incl. Structural) |
| الوصف: | We present observations of ≳10–100 keV nucleon−1 suprathermal (ST) H, He, O, and Fe ions associated with crossings of the heliospheric current sheet (HCS) at radial distances of <0.1 au from the Sun. Our key findings are as follows: (1) very few heavy ions are detected during the first full crossing, the heavy-ion intensities are reduced during the second partial crossing and peak just after the second crossing; (2) ion arrival times exhibit no velocity dispersion; (3) He pitch-angle distributions track the magnetic field polarity reversal and show up to ∼10:1 anti-sunward, field-aligned flows and beams closer to the HCS that become nearly isotropic farther from the HCS; (4) the He spectrum steepens either side of the HCS, and the He, O, and Fe spectra exhibit power laws of the form ∼E−4–E6; and (5) maximum energies EX increase with the ion's charge-to-mass (Q/M) ratio as ${E}_{X}/{E}_{H}\propto {({Q}_{X}/{M}_{X})}^{\delta }$, where δ ∼ 0.65–0.76, assuming that the average Q states are similar to those measured in gradual and impulsive solar energetic particle events at 1 au. The absence of velocity dispersion in combination with strong field-aligned anisotropies closer to the HCS appears to rule out solar flares and near-Sun coronal-mass-ejection-driven shocks. These new observations present challenges not only for mechanisms that employ direct parallel electric fields and organize maximum energies according to E/Q but also for local diffusive and magnetic-reconnection-driven acceleration models. Reevaluation of our current understanding of the production and transport of energetic ions is necessary to understand this near-solar, current-sheet-associated population of ST ions. |
| نوع الوثيقة: | article in journal/newspaper |
| اللغة: | English |
| تدمد: | 0004-637X |
| Relation: | The Astrophysical Journal: an international review of astronomy and astronomical physics; http://hdl.handle.net/10044/1/99032; ST/S000364/1 |
| DOI: | 10.3847/1538-4357/ac4961 |
| الاتاحة: | http://hdl.handle.net/10044/1/99032 https://doi.org/10.3847/1538-4357/ac4961 |
| Rights: | © 2022. The Author(s). Published by the American Astronomical Society. Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. ; http://creativecommons.org/licenses/by/4.0/ |
| رقم الانضمام: | edsbas.ACAB5962 |
| قاعدة البيانات: | BASE |
Full Text Finder | تدمد: | 0004637X |
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| DOI: | 10.3847/1538-4357/ac4961 |