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Related papers: Chromospheric Extension of the MURaM Code

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Increasingly realistic simulations of the corona are used to predict synthetic observables for instruments onboard both existing and upcoming heliophysics space missions. Synthetic observables play an important role in constraining coronal…

Solar and Stellar Astrophysics · Physics 2025-01-28 Cosima Alexandra Breu , Ineke De Moortel , Hardi Peter , Sami Khan Solanki

Physically realistic models of stellar spectra are needed in a variety of astronomical studies, from the analysis of fundamental stellar parameters, to studies of exoplanets and stellar populations in galaxies. Here we present a new version…

Solar and Stellar Astrophysics · Physics 2023-01-11 Jeffrey M. Gerber , Ekaterina Magg , Bertrand Plez , Maria Bergemann , Ulrike Heiter , Terese Olander , Richard Hoppe

We have used our PHOENIX multi-purpose model atmosphere code to calculate atmospheric models that represent novae in the optically thick wind phases of their outburst. We have improved the treatment of NLTE effects by expanding the number…

Astrophysics · Physics 2009-10-31 C. Ian Short , Peter H. Hauschildt , E. Baron

Current models of the solar wind must approximate (or ignore) the small-scale dynamics within the solar atmosphere, however these are likely important in shaping the emerging wave-turbulence spectrum and ultimately heating/accelerating the…

Solar and Stellar Astrophysics · Physics 2022-09-28 Adam J. Finley , Sacha A. Brun , Mats Carlsson , Mikolaj Szydlarski , Viggo Hansteen , Munehito Shoda

A cosmological hydrodynamic code is described, which includes a routine to compute cosmic ray acceleration and transport in a simplified way. The routine was designed to follow explicitly diffusive acceleration at shocks, and second-order…

Astrophysics · Physics 2007-05-23 Dongsu Ryu , Francesco Miniati , Tom W. Jones , Hyesung Kang

We explore the response of the He II 304 {\AA} and He I 584 {\AA} line intensities to electron beam heating in solar flares using radiative hydrodynamic simulations. Comparing different electron beams parameters, we found that the…

Solar and Stellar Astrophysics · Physics 2015-12-14 Paulo J. A. Simões , Lyndsay Fletcher , Nicolas Labrosse , Graham S. Kerr

Heating signatures from small-scale magnetic reconnection events in the solar atmosphere have proven to be difficult to detect through observations. Numerical models that reproduce flaring conditions are essential in the understanding of…

Solar and Stellar Astrophysics · Physics 2022-03-30 H. Bakke , M. Carlsson , L. Rouppe van der Voort , B. V. Gudiksen , V. Polito , P. Testa , B. De Pontieu

We proposed that the use of an approximate "jump condition" at the solar transition region permits fast and accurate numerical solutions of the one dimensional hydrodynamic equations when the corona undergoes impulsive heating. In…

Solar and Stellar Astrophysics · Physics 2017-08-30 C. D. Johnston , A. W. Hood , P. J. Cargill , I. De Moortel

Low-frequency turbulence in the solar chromosphere remains poorly understood. We address 1) the sources of low-frequency turbulence that potentially heat the chromosphere, and 2) how turbulence is transported and dissipated throughout the…

Impulsive nanoflares are expected to transiently heat the plasma confined in coronal loops to temperatures of the order of 10 MK. Such hot plasma is hardly detected in quiet and active regions, outside flares. During rapid and short heat…

Astrophysics · Physics 2009-11-13 Fabio Reale , Salvatore Orlando

Radiative cooling plays a crucial role in the dynamics of many astrophysical flows, and is particularly important in the dense shocked gas within Herbig-Haro (HH) objects and stellar jets. Simulating cooling processes accurately is…

High Energy Astrophysical Phenomena · Physics 2018-11-19 E. C. Hansen , P. Hartigan , A. Frank. A. Wright , J. C. Raymond

We analyze the important formation processes for the Mg I 457.1 nm line. This line is an intercom- bination line and the source function is close to the local thermodynamic equilibrium (LTE) value. The strong coupling to the local…

Solar and Stellar Astrophysics · Physics 2011-02-11 Oystein Langangen , Mats Carlsson

Observations of some starburst-driven galactic superwinds suggest that strong radiative cooling could play a key role in the nature of feedback and the formation of stars and molecular gas in star-forming galaxies. These catastrophically…

Astrophysics of Galaxies · Physics 2022-09-30 A. Danehkar , M. S. Oey , W. J. Gray

We present the results of a series of calculations studying the collapse of molecular cloud cores performed using a three-dimensional smoothed particle hydr odynamics code with radiative transfer in the flux-limited diffusion approximation.…

Astrophysics · Physics 2009-11-13 Stuart C. Whitehouse , Matthew R. Bate

Absorption-line measurements of the circumgalactic medium (CGM) display a highly non-uniform distribution of lower ionization state species accompanied by more widespread higher ionization state material. This suggests that the CGM is a…

Astrophysics of Galaxies · Physics 2022-03-14 Edward Buie , Evan Scannapieco , G. Mark Voit

Observations of the upper chromosphere shows an enormous amount of intricate fine structure. Much of this comes in the form of linear features which are most often assumed to be well aligned with the direction of the magnetic field in the…

Solar and Stellar Astrophysics · Physics 2017-10-23 Juan Martínez-Sykora , Bart De Pontieu , Mats Carlsson , Viggo Hansteen

Acceleration and transport of high-energy particles and fluid dynamics of atmospheric plasma are interrelated aspects of solar flares. We present here self-consistently combined Fokker-Planck modeling of particles and hydrodynamic…

Solar and Stellar Astrophysics · Physics 2009-09-28 Wei Liu , Vahe Petrosian , John T. Mariska

During a solar flare, it is believed that reconnection takes place in the corona followed by fast energy transport to the chromosphere. The resulting intense heating strongly disturbs the chromospheric structure, and induces complex…

Solar and Stellar Astrophysics · Physics 2019-04-30 Christopher M. J. Osborne , John A. Armstrong , Lyndsay Fletcher

We have reanalyzed SUMER observations of a parcel of coronal gas using new collisional ionization equilibrium (CIE) calculations. These improved CIE fractional abundances were calculated using state-of-the-art electron-ion recombination…

Astrophysics · Physics 2011-02-11 P. Bryans , E. Landi , D. W. Savin

The Lyman Continuum (LyC; $<911.12$\AA) forms at the top of the chromosphere in the quiet-Sun, making LyC a powerful tool for probing the chromospheric plasma during solar flares. To understand the effects of non-thermal energy deposition…

Solar and Stellar Astrophysics · Physics 2023-03-01 Shaun A. McLaughlin , Ryan O. Milligan , Graham S. Kerr , Aaron J. Monson , Paulo J. A. Simões , Mihalis Mathioudakis