scholarly journals Simulation of 10830 Å absorption with a 3D hydrodynamic model reveals the solar He abundance in upper atmosphere of WASP-107b

2021 ◽  
Author(s):  
M L Khodachenko ◽  
I F Shaikhislamov ◽  
L Fossati ◽  
H Lammer ◽  
M S Rumenskikh ◽  
...  
Keyword(s):  
Metastable State ◽  
Radiation Pressure ◽  
Hydrodynamic Model ◽  
Planetary System ◽  
Fluid Model ◽  
Upper Atmosphere ◽  
Helium Abundance ◽  
Velocity Range ◽  
Impact Processes ◽  
Self Consistent

Abstract Transmission spectroscopy of WASP-107b revealed 7–8 per cent absorption at the position of metastable HeI triplet at 10830 Å in the velocity range of [-20; 10] km/s. This absorption is stronger than that measured in other exoplanets. With a dedicated 3D self-consistent hydrodynamic multi-fluid model we simulated the expanding upper atmosphere of WASP-107b and reproduced within the observations accuracy the measured HeI absorption profiles, constraining the stellar XUV flux to (6–10) erg cm−2 s−1 at 1 a.u., and the upper atmosphere helium abundance He/H to 0.075–0.15. The radiation pressure acting on the metastable HeI atoms was shown to be an important factor influencing the absorption profiles. Its effect is counterbalanced by the collisional depopulation of the HeI metastable state. Altogether, the observed HeI absorption in WASP-107b can be interpreted with the expected reasonable parameters of the stellar-planetary system and appropriate account of the electron and atom impact processes.

Self-consistent hydrodynamic two-fluid model of vortex plasma

2021 ◽  
Vol 33 (3) ◽  
pp. 037116
Author(s):  
Victor L. Mironov
Keyword(s):  
Fluid Model ◽  
Self Consistent ◽  
Two Fluid Model ◽  
Two Fluid

scholarly journals Dynamics of Alfvén waves in partially ionized astrophysical plasmas

2009 ◽  
Vol 76 (3-4) ◽  
pp. 305-315 ◽  
Author(s):  
DASTGEER SHAIKH
Keyword(s):  
Energy Transfer ◽  
Fluid Model ◽  
Propagation Speed ◽  
Neutral Atoms ◽  
Astrophysical Plasmas ◽  
Exchange Processes ◽  
Consistent Model ◽  
Self Consistent ◽  
Partially Ionized ◽  
Energy Equations

AbstractWe develop a two dimensional, self-consistent, compressible fluid model to study evolution of Alfvenic modes in partially ionized astrophysical and space plasmas. The partially ionized plasma consists mainly of electrons, ions and significant neutral atoms. The nonlinear interactions amongst these species take place predominantly through direct collision or charge exchange processes. Our model uniquely describe the interaction processes between two distinctly evolving fluids. In our model, the electrons and ions are described by a single-fluid compressible magnetohydrodynamic (MHD) model and are coupled self-consistently to the neutral fluid via compressible hydrodynamic equations. Both plasma and neutral fluids are treated with different energy equations that adequately enable us to monitor non-adiabatic and thermal energy exchange processes between these two distinct fluids. Based on our self-consistent model, we find that the propagation speed of Alfvenic modes in space and astrophysical plasma is slowed down because these waves are damped predominantly due to direct collisions with the neutral atoms. Consequently, energy transfer takes place between plasma and neutral fluids. We describe the mode coupling processes that lead to the energy transfer between the plasma and neutral and corresponding spectral features.

A self-consistent fluid model for radio-frequency discharges in SiH4–H2 compared to experiments

1997 ◽  
Vol 82 (5) ◽  
pp. 2060-2071 ◽  
Author(s):  
G. J. Nienhuis ◽  
W. J. Goedheer ◽  
E. A. G. Hamers ◽  
W. G. J. H. M. van Sark ◽  
J. Bezemer
Keyword(s):  
Radio Frequency ◽  
Fluid Model ◽  
Self Consistent ◽  
Radio Frequency Discharges

scholarly journals Fast ignitor: Fluid dynamics of channel formation and laser beam propagation

1997 ◽  
Vol 15 (4) ◽  
pp. 541-556 ◽  
Author(s):  
S. Hain ◽  
P. Mulser
Keyword(s):  
Electromagnetic Wave ◽  
Radiation Pressure ◽  
Fluid Model ◽  
Fluid Dynamic ◽  
Beam Propagation ◽  
Dense Matter ◽  
Nonlinear Propagation ◽  
Channel Formation ◽  
Fast Ignitor ◽  
Ablation Pressure

The concept of fast ignitor is intimately connected with the fundamental phenomenon of ultra-intense light beam propagation through dense matter in which kinetic effects combine with radiation pressure dominated hydrodynamics to form a complex scenario of extremely non-linear physics. In this paper, the fluid dynamic aspect of channel formation in a highly over-dense plasma is studied and possible attenuation mechanisms of the propagating pulse are evaluated in one dimension. Under the assumption that mass ablation reaches a quasistationary state, the radiation-assisted ablation pressure, the speed of the bow shock, and the density steepening around the critical point are determined self-consistently from the ID fluid conservation relations and the electromagnetic wave equation. Due to ponderomotive profile steepening, the ablation pressure is reduced by 40% in the subsonic region and is dominated by the radiation pressure in the supersonic domain. Channel lengths are calculated for various intensities and pellet compression ratios. Likewise, the nonlinear propagation of a superintense electromagnetic wave in an underdense plasma channel is investigated for the ID case with the help of a relativistic fluid model.

scholarly journals LIDT-DD: A New Self-Consistent Debris Disc Model Including Radiation Pressure and Coupling Dynamical and Collisional Evolution

2013 ◽  
Vol 8 (S299) ◽  
pp. 346-347
Author(s):  
Q. Kral ◽  
P. Thebault ◽  
S. Charnoz
Keyword(s):  
Radiation Pressure ◽  
New Model ◽  
Disc Model ◽  
Self Consistent ◽  
Radiation Forces ◽  
Coupling Dynamics ◽  
Long Timescales ◽  
Collisional Evolution

AbstractThe first attempt at developing a fully self-consistent code coupling dynamics and collisions to study debris discs (Kral et al. 2013) is presented. So far, these two crucial mechanisms were studied separately, with N-body and statistical collisional codes respectively, because of stringent computational constraints.We present a new model named LIDT-DD which is able to follow over long timescales the coupled evolution of dynamics (including radiation forces) and collisions in a self-consistent way.

Self-consistent gyroviscous fluid model of rotational discontinuities

1991 ◽  
Vol 96 (A9) ◽  
pp. 15767-15778 ◽  
Author(s):  
L.-N. Hau ◽  
B. U. Ö Sonnerup
Keyword(s):  
Fluid Model ◽  
Self Consistent

scholarly journals On the thermal atmospheric escape of π Men c

2021 ◽  
Author(s):  
E. S. Kalinicheva ◽  
◽  
V. I. Shematovich ◽  
Ya. N. Pavlyuchenkov ◽  
◽  
...  
Keyword(s):  
Mass Loss ◽  
Loss Rate ◽  
Mass Loss Rate ◽  
Upper Atmosphere ◽  
One Dimensional ◽  
Atmospheric Escape ◽  
Self Consistent ◽  
Atmospheric Mass ◽  
Suprathermal Particles

In this work we present the results of the modeling of exoplanet pi Men c upper atmosphere, produced using the previously developed one-dimensional self-consistent aeronomic model. The model used takes into account the contribution of suprathermal particles, which significantly refines the heating function of the atmosphere. The hight profiles of temperature, velocity and density were obtained, the atmospheric mass-loss rate was calculated. The presence of two hight-scales in the structure of the atmosphere was found: the first corresponds to a relatively dense stationary atmosphere, the second to a more rarefied corona.

scholarly journals PRODUCTION OF THERMAL PHOTONS IN A SIMPLE CHIRAL-HYDRODYNAMIC MODEL

2012 ◽  
Vol 18 ◽  
pp. 216-220
Author(s):  
J. PERALTA-RAMOS ◽  
M. S. NAKWACKI
Keyword(s):  
Boltzmann Equation ◽  
Equation Of State ◽  
Shear Viscosity ◽  
Hydrodynamic Model ◽  
Order Theory ◽  
Second Order ◽  
Temperature Dependent ◽  
Dissipative Effects ◽  
Linearized Boltzmann Equation ◽  
Self Consistent

We use a self-consistent chiral-hydrodynamic formalism which combines the linear σ model with second-order hydrodynamics in 2 + 1 dimensions to compute the spectrum of thermal photons produced in Au+Au collisions at [Formula: see text]. The temperature-dependent shear viscosity of the model, η, is calculated from the linearized Boltzmann equation. We compare the results obtained in the chiral-hydrodynamic model to those obtained in the second-order theory with a Lattice QCD equation of state and a temperature-independent value of η/s. We find that the thermal photon production is significantly larger in the latter model due to a slower evolution and larger dissipative effects.

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