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Parker Solar Probe Observations of Near-f $_Ce$ Harmonic Emissions in the Near-Sun Solar Wind and Their Dependence on the Magnetic Field Direction
| Author | Tigik, Sabrina; Vaivads, Andris; Malaspina, David; Bale, Stuart; |
| Keywords | Parker Data Used; Space plasmas; Plasma physics; Solar wind; 1544; 2089; 1534; Astrophysics - Solar and Stellar Astrophysics; Physics - Plasma Physics; Physics - Space Physics |
| Abstract | Wave emissions at frequencies near electron gyrofrequency harmonics are observed at small heliocentric distances below about 40 R $_\ensuremath\odot$ and are known to occur in regions with quiescent magnetic fields. We show the close connection of these waves to the large-scale properties of the magnetic field. Near electron gyrofrequency harmonic emissions occur only when the ambient magnetic field points to a narrow range of directions bounded by polar and azimuthal angular ranges in the RTN coordinate system of correspondingly 80\textdegree \ensuremath\lesssim \ensuremath\theta $_ B $ \ensuremath\lesssim 100\textdegree and 10\textdegree \ensuremath\lesssim \ensuremath\phi $_ B $ \ensuremath\lesssim 30\textdegree. We show that the amplitudes of wave emissions are highest when both angles are close to the center of their respective angular interval favorable to wave emissions. The intensity of wave emissions correlates with the magnetic field angular changes at both large and small timescales. Wave emissions intervals correlate with intervals of decreases in the amplitudes of broadband magnetic fluctuations at low frequencies of 10-100 Hz. We discuss possible generation mechanisms of the waves. |
| Year of Publication | 2022 |
| Journal | \apj |
| Volume | 936 |
| Number of Pages | 7 |
| Section | |
| Date Published | sep |
| ISBN | |
| URL | |
| DOI | 10.3847/1538-4357/ac8473 |
