Radiative transfer in cylindrical threads with incident
 radiation

Gouttebroze, P.; Labrosse, Nicolas

doi:10.1051/0004-6361/200811483

Cited by 37 publications

(48 citation statements)

References 15 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…it can be reduced to the range [0, π]. To interpolate across the azimuthal grid, a Fourier method is used (Gouttebroze, 2005):…”

Section: Geometry and Integration Methodsmentioning

confidence: 99%

“…However, a 2D cross-section of a cylinder can be used as a suitable approximation. We used the 2D cylindrical radiative transfer code for this, which considers both hydrogen and helium, of Gouttebroze and Labrosse (2009), referred to as C2D2E. It considers a 5-level plus continuum hydrogen atom and a 33-level plus continuum helium atom, including 29 levels for He I and 4 levels for He II.…”

Section: Modellingmentioning

confidence: 99%

See 1 more Smart Citation

Solar Prominence Modelling and Plasma Diagnostics at ALMA Wavelengths

Rodger

Labrosse

2017

Sol Phys

View full text Add to dashboard Cite

Our aim is to test potential solar prominence plasma diagnostics as obtained with the new solar capability of the Atacama Large Millimeter/submillimeter Array (ALMA). We investigate the thermal and plasma diagnostic potential of ALMA for solar prominences through the computation of brightness temperatures at ALMA wavelengths. The brightness temperature, for a chosen line of sight, is calculated using the densities of electrons, hydrogen, and helium obtained from a radiative transfer code under non-local thermodynamic equilibrium (non-LTE) conditions, as well as the input internal parameters of the prominence model in consideration. Two distinct sets of prominence models were used: isothermal-isobaric fine-structure threads, and large-scale structures with radially increasing temperature distributions representing the prominence-to-corona transition region. We compute brightness temperatures over the range of wavelengths in which ALMA is capable of observing (0.32 -9.6 mm), however, we particularly focus on the bands available to solar observers in ALMA cycles 4 and 5, namely 2.6 -3.6 mm (Band 3) and 1.1 -1.4 mm (Band 6). We show how the computed brightness temperatures and optical thicknesses in our models vary with the plasma parameters (temperature and pressure) and the wavelength of observation. We then study how ALMA observables such as the ratio of brightness temperatures at two frequencies can be used to estimate the optical thickness and the emission measure for isothermal and non-isothermal prominences. From this study we conclude that for both sets of models, ALMA presents a strong thermal diagnostic capability, provided that the interpretation of observations is supported by the use of non-LTE simulation results.

show abstract

“…it can be reduced to the range [0, π]. To interpolate across the azimuthal grid, a Fourier method is used (Gouttebroze, 2005):…”

Section: Geometry and Integration Methodsmentioning

confidence: 99%

Section: Modellingmentioning

confidence: 99%

Solar Prominence Modelling and Plasma Diagnostics at ALMA Wavelengths

Rodger

Labrosse

2017

Sol Phys

View full text Add to dashboard Cite

show abstract

“…All models have a constant microturbulent velocity of 5 km s −1 . Helium is taken into account only for the density determination but not to contribute to the electron density at the low temperatures considered here -note that a helium contribution to the electron density was recently considered for cylinders by Gouttebroze & Labrosse (2009). We took the helium abundance to be equal to 0.1.…”

Section: Model Calculationsmentioning

confidence: 99%

Radiative equilibrium in solar prominences reconsidered

Heinzel

Anzer

2012

A&A

View full text Add to dashboard Cite

Aims. We reconsider the question which kinetic temperatures can lead to prominence configurations that are in radiative equilibrium. We compare these temperatures to those from other calculations. Methods. For this purpose we solved the full non-LTE radiative-transfer problem for a gas consisting of hydrogen, helium and calcium. We used simple isobaric 1D slabs and began with isothermal models. Then we solved the radiative-relaxation problem and determined the radiative-equilibrium conditions within the whole slab. Results. By adding the calcium radiative losses, we found that these equilibrium temperatures are considerably lower than those obtained for a pure hydrogen gas. This is because the newly calculated CaII line losses appear to play a significant role in the energy balance, similar to chromospheric conditions. The equilibrium temperatures obtained span the range between 4400−9500 K, depending on the gas pressure and slab thickness.

show abstract

“…On the other hand, δ He indicates the helium ionization degree. A realistic value of this parameter is δ He = 0.1 according to the results of Gouttebroze & Labrosse (2009). From Eq.…”

Section: Equilibrium and Basic Equationsmentioning

confidence: 99%

“…The plasma is assumed to be partially ionized, because electrons, protons, neutral hydrogen, neutral helium (He i), and singly ionized helium (He ii) are the species taken into account. Recent studies by Gouttebroze & Labrosse (2009) Forteza et al (2007Forteza et al ( , 2008, the derivation of the basic MHD equations for a non-adiabatic, partially ionized, singlefluid plasma has been generalized by now considering five different species, allowing us to study how the presence of neutral and singly ionized helium affects their previous results. This paper is organized as follows.…”

Section: Introductionmentioning

confidence: 99%

Time damping of non-adiabatic magnetohydrodynamic waves in a partially ionized prominence plasma: effect of helium

Soler

Oliver

Ballester

2010

A&A

View full text Add to dashboard Cite

Context. Prominences are partially ionized, magnetized plasmas embedded in the solar corona. Damped oscillations and propagating waves are commonly observed. These oscillations have been interpreted in terms of magnetohydrodynamic (MHD) waves. Ion-neutral collisions and non-adiabatic effects (radiation losses and thermal conduction) have been proposed as damping mechanisms. Aims. We study the effect of the presence of helium on the time damping of non-adiabatic MHD waves in a plasma composed by electrons, protons, neutral hydrogen, neutral helium (He i), and singly ionized helium (He ii) in the single-fluid approximation.Methods. The dispersion relation of linear non-adiabatic MHD waves in a homogeneous, unbounded, and partially ionized prominence medium is derived. We compute the period and the damping time of Alfvén, slow, fast, and thermal waves. A parametric study of the ratio of the damping time to the period with respect to the helium abundance is performed.Results. The efficiency of ion-neutral collisions, as well as thermal conduction, is increased by the presence of helium. However, if realistic abundances of helium in prominences (∼10%) are considered, this has a minor influence on the wave damping. Conclusions. The presence of helium can be safely neglected in studies of MHD waves in partially ionized prominence plasmas.

show abstract

Radiative transfer in cylindrical threads with incident radiation

Cited by 37 publications

References 15 publications

Solar Prominence Modelling and Plasma Diagnostics at ALMA Wavelengths

Solar Prominence Modelling and Plasma Diagnostics at ALMA Wavelengths

Radiative equilibrium in solar prominences reconsidered

Time damping of non-adiabatic magnetohydrodynamic waves in a partially ionized prominence plasma: effect of helium

Contact Info

Product

Resources

About