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Magnetic helicity is approximately conserved in resistive MHD models. It quantifies the entanglement of the magnetic field within the plasma. The transport and removal of helicity is crucial in both the dynamo in the solar interior and…

Solar and Stellar Astrophysics · Physics 2020-03-25 Christopher Prior , Gareth Hawkes , Mitch Berger

We study the turbulent velocity dispersion spectra of the coexistent HCN and HCO+ molecular species as a function of length scale in the M17 star-forming molecular cloud. We show that the observed downward shift of the ion's spectrum…

Astrophysics · Physics 2009-11-13 Hua-bai Li , Martin Houde

The higher order statistics of magnetic field magnitude fluctuations in the fast quiet solar wind are quantified systematically scale-by-scale for the first time. We find a single global non-Gaussian scale free behaviour from minutes to…

Space Physics · Physics 2015-05-28 B. Hnat , S. C. Chapman , G. Gogoberidze , R. Wicks

A problem of magnetosphere formation on ion inertia scale around weakly magnetized bodies is investigated by means of laboratory experiment, analytical analysis and 2.5D Hall MHD simulation. Experimental evidence of specific magnetic field…

The interplay between gravity, turbulence and the magnetic field determines the evolution of the molecular ISM and the formation of the stars. In spite of growing interests, there remains a lack of understanding of the importance of…

Astrophysics of Galaxies · Physics 2017-11-27 Guang-Xing Li , Andreas Burkert

The presence of magneto-acoustic waves in magnetic structures in the solar atmosphere is well-documented. Applying the technique of solar magneto-seismology (SMS) allows us to infer the background properties of these structures. Here, we…

Solar and Stellar Astrophysics · Physics 2016-01-27 N. Freij , I. Dorotovic , R. J. Morton , M. S. Ruderman , V. Karlovsky , R. Erdekyi

The magnetised solar wind modulates the Galactic cosmic ray flux in the heliosphere up to rigidities as high as 40 GeV. In this work, we present a new and straightforward extension of the popular, but limited force-field model, thus…

High Energy Astrophysical Phenomena · Physics 2019-12-25 Marco Kuhlen , Philipp Mertsch

AIM: To study the variation of the angular momentum and the rotational kinetic energy of the Sun, and associated variations in the gravitational multipole moments, on a timescale of the solar cycle. METHOD: Inverting helioseismic rotational…

Astrophysics · Physics 2009-11-13 H. M. Antia , S. M. Chitre , D. O. Gough

The cosmic rays differential intensity inside the heliosphere, for energy below 30 GeV/nuc, depends on solar activity and interplanetary magnetic field polarity. This variation, termed solar modulation, is described using a 2-D (radius and…

Solar and Stellar Astrophysics · Physics 2015-06-12 P. Bobik , G. Boella , M. J. Boschini , C. Consolandi , S. Della Torre , M. Gervasi , D. Grandi , K. Kudela , S. Pensotti , P. G. Rancoita , D. Rozza , M. Tacconi

The degree of deviation from the thermodynamic equilibrium in the ion velocity distribution functions (VDFs), measured by the Magnetospheric Multiscale (MMS) mission in the Earth's turbulent magnetosheath, is quantitatively investigated.…

Knowledge about the background solar wind plays a crucial role in the framework of space weather forecasting. In-situ measurements of the background solar wind are only available for a few points in the heliosphere where spacecraft are…

Solar and Stellar Astrophysics · Physics 2013-12-05 C. Gressl , A. M. Veronig , M. Temmer , D. Odstrcil , J. A. Linker , Z. Mikic , P. Riley

A well-known property of solar wind plasma turbulence is the observed anisotropy of the autocorrelations, or equivalently the spectra, of velocity and magnetic field fluctuations. Here we explore the related but apparently not well-studied…

Aims: The interactions of velocity scales on the Sun's surface, from granulation to supergranulation are still not understood, nor are their interaction with magnetic fields. We thus aim at giving a better description of dynamics in the…

Solar and Stellar Astrophysics · Physics 2009-02-16 T. Roudier , M. Rieutord , D. Brito , F. Rincon , J. M. Malherbe , N. Meunier , T. Berger , Z. Frank

In situ spacecraft data on the solar wind show events identified as magnetic reconnection with outflows and apparent "`$X$-lines" $10^{3-4}$ times ion scales. To understand the role of turbulence at these scales, we make a case study of an…

We examine statistics of magnetic field vector components to explore how intermittency evolves from near sun plasma to radial distances as large as 10 au. Statistics entering the analysis include auto-correlation, magnetic structure…

Observational evidence for the existence of cosmic magnetic fields in intergalactic space coherent over Mpc scales is presented. Using an unprecedentedly large sample of Faraday rotation measures of radio sources from the NRAO VLA Sky…

Cosmology and Nongalactic Astrophysics · Physics 2010-07-16 Jounghun Lee , Ue-Li Pen , A. Russell Taylor , Jeroen M. Stil , Caleb Sunstrum

Two sequences of solar images obtained by the Transition Region and Coronal Explorer in three UV passbands are studied using wavelet and Fourier analysis and compared to the photospheric magnetic flux measured by the Michelson Doppler…

Parker Solar Probe (PSP) observations during its first encounter at 35.7 $R_\odot$ have shown the presence of magnetic field lines which are strongly perturbed to the point that they produce local inversions of the radial magnetic field,…

Magnetic helicity is a fundamental constraint in both ideal and resistive magnetohydrodynamics. Measurements of magnetic helicity density on the Sun and other stars are used to interpret the internal behaviour of the dynamo generating the…

Solar and Stellar Astrophysics · Physics 2022-11-03 Parag Gupta , Radostin D. Simitev , David MacTaggart

Aims. Linear magnetohydrostatic (MHS) models of solar magnetic fields balance plasma pressure gradients, gravity and Lorentz forces where the current density is composed of a linear force-free component and a cross-field component that…

Solar and Stellar Astrophysics · Physics 2013-07-26 David MacTaggart , Abdulaziz Elsheikh , James McLaughlin , Radostin Simitev