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Plasma turbulence cascading from MHD to kinetic scales in the heliospheric plasma is believed to play a key role in coronal heating and fast solar wind acceleration, but the properties of the turbulence remain poorly constrained by…

Solar and Stellar Astrophysics · Physics 2026-02-03 Eduard P. Kontar , A. Gordon Emslie , Daniel L. Clarkson , Alexander Pitna

Radio waves are strongly scattered in the solar wind, so that their apparent sources seem to be considerably larger and shifted than the actual ones. Since the scattering depends on the spectrum of density turbulence, better understanding…

Internal waves with frequency larger than twice the local minimum allowable wave frequency can be susceptible to parametric subharmonic instability (PSI). This instability draws energy from the wave and provides a mechanism for generating…

Fluid Dynamics · Physics 2026-05-28 Logan Knudsen , Jacob Wenegrat , James Hilditch , Leif Thomas

Finding low-mass planets around solar-type stars requires to understand the physical variability of the host star, which greatly exceeds the planet-induced radial-velocity modulation. This project aims at analyzing - observationally and…

Solar and Stellar Astrophysics · Physics 2025-09-24 Dainis Dravins , Hans-Günter Ludwig

This letter describes a new phenomenon on the Parker Solar Probe of recurring plasma density enhancements that have $\Delta$n/n ~10% and that occur at a repetition rate of ~5 Hz. They were observed sporadically for about five hours between…

Solar and Stellar Astrophysics · Physics 2023-08-01 F. S. Mozer , O. Agapitov , S. D. Bale , R. Livi , O. Romeo , K. Sauer , I. Y. Vasko , J. Verniero

We make use of the Parker Solar Probe (PSP) data to explore the nature of solar wind turbulence focusing on the Alfv\'enic character and power spectra of the fluctuations and their dependence on distance and context (i.e. large scale solar…

Microturbulence, i.e. enhanced fluctuations of plasma density, electric and magnetic fields, is of great interest in astrophysical plasmas, but occurs on spatial scales far too small to resolve by remote sensing, e.g., at ~ 1-100 cm in the…

Astrophysics · Physics 2009-11-13 Gelu M. Nita , Dale E. Gary , Gregory D. Fleishman

We use the plasma density based on measurements of the probe-to-spacecraft potential in combination with magnetic field measurements by MAG to study fields and density fluctuations in the solar wind observed by Solar Orbiter during the…

Slow magnetoacoustic waves in a static background provide a seismological tool to probe the solar atmosphere in the analytic frame. By analyzing the spatiotemporal variation of the electron number density of plume structure in coronal holes…

Solar and Stellar Astrophysics · Physics 2020-09-09 Il-Hyun Cho , Valery M. Nakariakov , Yong-Jae Moon , Jin-Yi Lee , Dae Jung Yu , Kyung-Suk Cho , Vasyl Yurchyshyn , Harim Lee

Parker Solar Probe measurements have recently shown that coherent fast magnetosonic and Alfv\'{e}n ion-cyclotron waves are abundant in the solar wind and can be accompanied by higher-frequency electrostatic fluctuations. In this letter we…

Solar and Stellar Astrophysics · Physics 2024-04-26 I. Y. Vasko , F. S. Mozer , T. Bowen , J. Verniero , X. An , A. V. Artemyev , J. W. Bonnell , J. Halekas , I. V. Kuzichev

We present a measurement of the spectral index of density fluctuations between ion and electron scales in solar wind turbulence using the EFI instrument on the ARTEMIS spacecraft. The mean spectral index at 1 AU was found to be -2.75 +/-…

Space Physics · Physics 2012-07-17 C. H. K. Chen , C. S. Salem , J. W. Bonnell , F. S. Mozer , S. D. Bale

Parker Solar Probe (PSP) observed sub-Alfvenic solar wind intervals during encounters 8 - 14, and low-frequency magnetohydrodynamic turbulence in these regions may differ from that in super-Alfvenic wind. We apply a new mode-decomposition…

Treatments of the radio scattering due to density turbulence in the solar wind typically employ asymptotic approximations to the phase structure function. We use a general structure function (GSF) that straddles the asymptotic limits and…

Solar and Stellar Astrophysics · Physics 2015-09-28 Madhusudan Ingale

We study the acoustic properties of the solar chromosphere in the high-frequency regime using a time sequence of velocity measurements in the chromospheric Ca II 854.2 nm line taken with the Interferometric Bidimensional Spectrometer…

Astrophysics · Physics 2010-11-11 K. P. Reardon , F. Lepreti , V. Carbone , A. Vecchio

We analyzed intermittency in the solar wind, as observed on the ecliptic plane, looking at magnetic field and velocity fluctuations between 0.3 and 1 AU, for both fast and slow wind and for compressive and directional fluctuations. Our…

Astrophysics · Physics 2015-06-24 R. Bruno , V. Carbone , L. Sorriso-Valvo , B. Bavassano

Shear Alfven wave parametric decay instability (PDI) provides a potential path toward significant wave dissipation and plasma heating. However, fundamental questions regarding how PDI is excited in a realistic three-dimensional (3D) open…

Plasma Physics · Physics 2024-05-03 Feiyu Li , Xiangrong Fu , Seth Dorfman

Electric field measurements of the Time Domain Sampler (TDS) receiver, part of the Radio and Plasma Waves (RPW) instrument on board Solar Orbiter, often exhibit very intense broadband wave emissions at frequencies below 20~kHz in the…

The power spectrum of magnetic-field fluctuations in the fast solar wind ($V_{\rm SW}> 500 \mbox{ km} \mbox{ s}^{-1}$) at magnetohydrodynamic (MHD) scales is characterized by two different power laws on either side of a break frequency…

The observed features of the radio sources indicate complex propagation effects embedded in the waves of solar radio bursts. In this work, we perform ray-tracing simulations on radio wave transport in the corona and interplanetary region…

Solar and Stellar Astrophysics · Physics 2021-03-24 PeiJin Zhang , ChuanBing Wang , Eduard P. Kontar

Using the local helioseismic technique of ring diagram we analyze the frequencies of high--degree f- and p-modes derived from both velocity and continuum intensity data observed by MDI. Fitting the spectra with asymmetric peak profiles, we…

Astrophysics · Physics 2011-02-11 S. C. Tripathy , H. M. Antia , Kiran Jain , F. Hill