Observational evidence for solar wind proton heating by ion-scale turbulence

Abstract

Based on in-situ measurements by Wind spacecraft from 2005 to 2015, this letter reports for the first time a clearly scale-dependent connection between proton temperatures and the turbulence in the solar wind. A statistical analysis of proton-scale turbulence shows that increasing helicity magnitudes correspond to steeper magnetic energy spectra. In particular, there exists a positive power-law correlation (with a slope $\sim 0.4$) between the proton perpendicular temperature and the turbulent magnetic energy at scales $0.3\lesssim k{\rho }_p\lesssim 1$, with $k$ being the wavenumber and ${\rho }_p$ being the proton gyroradius. These findings present evidence of solar wind heating by the proton-scale turbulence. They also provide insight and observational constraint on the physics of turbulent dissipation in the solar wind.

arXiv comment15 pages, 4 figures, accepted for publication in Geophysical Research Letters

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Cited by in corpus (4)

• Violation of the zeroth law of turbulence in space plasmas
• Magnetic helicity signature and its role in regulating magnetic energy spectra and proton temperatures in the solar wind
• Dependence of Solar Wind Proton Temperature on the Polarisation Properties of Alfvénic Fluctuations at Ion-kinetic Scales
• Growth of Outward Propagating Fast-Magnetosonic/Whistler Waves in the Inner Heliosphere Observed by Parker Solar Probe