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We develop a general method for the self consistent calculation of the hydrodynamics of an astrophysical object irradiated by a radiation field with an arbitrary strength and spectral energy distribution (SED). Using the XSTAR…

High Energy Astrophysical Phenomena · Physics 2017-03-22 Sergei Dyda , Randall Dannen , Tim Waters , Daniel Proga

Solar flare electron acceleration is an efficient process, but its properties (mechanism, location) are not well constrained. Via hard X-ray (HXR) emission, we routinely observe energetic electrons at the Sun, and sometimes we detect…

Solar and Stellar Astrophysics · Physics 2023-10-09 Ross Pallister , Natasha L. S. Jeffrey

The solar interior is filled with turbulent thermal convection, which plays a key role in the energy and momentum transport and the generation of the magnetic field. The turbulent flows in the solar interior cannot be optically detected due…

Solar and Stellar Astrophysics · Physics 2024-10-10 Hiroyuki Masaki , Hideyuki Hotta

The Reynolds number, Re, is an important quantity for describing a turbulent flow. It tells us about the bandwidth over which energy can cascade from large scales to smaller ones, prior to the onset of dissipation. However, calculating it…

Plasma Physics · Physics 2025-06-04 Daniel Wrench , Tulasi N. Parashar , Sean Oughton , Kevin de Lange , Marcus Frean

Understanding solar wind flows is crucial for unraveling the dynamics of the Sun's corona and improving space weather forecasting. However, the complex nature of the solar wind and the absence of reliable ground-truth data present…

Solar and Stellar Astrophysics · Physics 2024-10-04 Valmir Moraes Filho , Vadim Uritsy , Barbara Thompson

The solar atmosphere is composed of many species which are populated at different ionization and excitation levels. The upper chromosphere, transition region, and corona are nearly collisionless. Consequently, slippage between, for…

Solar and Stellar Astrophysics · Physics 2020-08-04 Juan Martínez-Sykora , Mikolaj Szydlarski , Viggo H. Hansteen , Bart De Pontieu

The atmosphere of the Sun is highly structured and dynamic in nature. From the photosphere and chromosphere into the transition region and the corona plasma-$\beta$ changes from above to below one, i.e. while in the lower atmosphere the…

Astrophysics · Physics 2008-11-26 H. Peter

We show that the coronal heating and the fast solar wind acceleration in the coronal holes are natural consequence of the footpoint fluctuations of the magnetic fields at the photosphere, by performing one-dimensional magnetohydrodynamical…

Astrophysics · Physics 2009-11-11 Takeru K. Suzuki , Shu-ichiro Inutsuka

We perform large-scale molecular dynamics simulations to study heated granular fluids in three dimensions. Granular particles dissipate their kinetic energy due to solid frictional interaction with other particles. The velocity of each…

Statistical Mechanics · Physics 2018-01-25 Prasenjit Das , Sanjay Puri , Moshe Schwartz

We present here numerical simulations of surface solar convection which cover a box of 30$\times30\times$3.2 Mm$^3$ with a resolution of 315$\times315\times$82, which is used to investigate the dynamics of scales larger than granulation. No…

Astrophysics · Physics 2010-11-11 M. Rieutord , H. -G. Ludwig , T. Roudier , A. Nordlund , R. Stein

The solar abundances have undergone a major downward revision in the last decade, reputedly as a result of employing 3D hydrodynamical simulations to model the inhomogeneous structure of the solar photosphere. The very low oxygen abundance…

Solar and Stellar Astrophysics · Physics 2009-10-27 E. Caffau , H. -G. Ludwig , M. Steffen

The aim of this work is to give new observational constraints on solar surface flows by determining the horizontal scale dependence of the velocity and intensity fields, as represented by their power spectra, and to offer some theoretical…

Solar and Stellar Astrophysics · Physics 2015-05-14 M. Rieutord , T. Roudier , F. Rincon , J. -M. Malherbe , N. Meunier , T. Berger , Z. Frank

(abridged) The interaction of a fast wind with a spherical Asymptotic Giant Branch (AGB) wind is thought to be the basic mechanism for shaping Pre-Planetary Nebulae (PPN) and later Planetary Nebulae (PN). Due to the large speed of the fast…

Astrophysics · Physics 2008-11-26 Matthias Stute , Raghvendra Sahai

We present simulations of a comet interacting with the solar wind. Such simulations are treated in the framework of the ideal, 2D magnetohydrodynamics (MHD), using the FLASH code in order to solve the equations of such a formalism. Besides,…

With the adaptation of the FLASH code we simulate magnetohydrodynamic-gravity waves and vortices as well as their response in the magnetized three-dimensional (3D) solar atmosphere at different heights to understand the localized energy…

Solar and Stellar Astrophysics · Physics 2015-06-17 K. Murawski , I. Ballai , A. K. Srivastava , D. Lee

The plasma of the lower solar atmosphere consists of mostly neutral particles, whereas the upper solar atmosphere is mostly ionised particles and electrons. A shock that propagates upwards in the solar atmosphere therefore undergoes a…

Solar and Stellar Astrophysics · Physics 2020-05-27 Ben Snow , Andrew Hillier

The heating of the solar wind is a key to understand its dynamics and acceleration process. The observed radial decrease of proton temperature in the solar wind is slow compared to the adiabatic prediction and it is thought to be caused by…

Space Physics · Physics 2026-03-03 Victor Montagud-Camps , Roland Grappin , Andrea Verdini

Scientific codes are an indispensable link between theory and experiment; in (astro-)plasma physics, such numerical tools are one window into the universe's most extreme flows of energy. The discretization of Maxwell's equations - needed to…

Computational Physics · Physics 2021-03-09 J. F. Mahlmann , M. A. Aloy , V. Mewes , P. Cerdá-Durán

Hydrodynamic simulations of granular convection predict the existence of supersonic flows covering ~3-4% of the solar surface at any time, but these flows have not been detected unambigously as yet. Using data from the spectropolarimeter…

Solar and Stellar Astrophysics · Physics 2009-07-22 L. R. Bellot Rubio

We study the solar emission of light dark sector particles that self-interact strongly enough to self-thermalize. The resulting outflow behaves like a fluid which accelerates under its own thermal pressure to highly relativistic bulk…

High Energy Physics - Phenomenology · Physics 2022-11-21 Jae Hyeok Chang , David E. Kaplan , Surjeet Rajendran , Harikrishnan Ramani , Erwin H. Tanin