scholarly journals P-mode leakage and Lyman-α intensity

2007 ◽  
Vol 3 (S247) ◽  
pp. 74-77 ◽  
Author(s):  
W. Finsterle ◽  
M. Haberreiter ◽  
S. Kosovichev ◽  
W. Schmutz
Keyword(s):  
Shock Waves ◽  
Wave Energy ◽  
Statistical Approach ◽  
Heating Process ◽  
Solar Chromosphere ◽  
Observational Test

AbstractWe present an observational test of the hypothesis that leaking p modes heat the solar chromosphere. The amplitude of the leaking p modes in magneto-acoustic portals is determined using MOTH and MDI data. We simulate the propagation of these modes into the chromosphere to determine the height where the wave energy is dissipated by shock waves. A statistical approach is then used to check if this heating process could account for the observed variability of the intensity in the Lyman-α emission.

Shock Waves and the Interpretation of the Chromospheric Calcium K-line

1972 ◽  
Vol 2 (3) ◽  
pp. 146-147 ◽  
Author(s):  
L. E. Cram
Keyword(s):  
Energy Source ◽  
Shock Waves ◽  
Energy Loss ◽  
Temperature Rise ◽  
Energy Input ◽  
Mechanical Energy ◽  
Theoretical Models ◽  
Radiative Energy ◽  
Heating Process ◽  
Radiative Energy Loss

Dissipation of shock waves has often been proposed as the energy source required to sustain the outward temperature rise in the solar atmosphere. Theoretical models for the heating process have been developed by equating the mechanical energy input to the radiative energy loss at each height, but neither of these processes is well understood, and the lack of data means that the models are necessarily crude.

scholarly journals Small-scale structure and dynamics of the lower solar atmosphere

2007 ◽  
Vol 3 (S247) ◽  
pp. 66-73 ◽  
Author(s):  
Sven Wedemeyer-Böhm ◽  
Friedrich Wöger
Keyword(s):  
Shock Waves ◽  
Three Dimensional ◽  
Small Scale ◽  
Solar Chromosphere ◽  
Hydrodynamic Simulations ◽  
Comprehensive Picture ◽  
Post Shock ◽  
Lower Solar Atmosphere ◽  
Shock Fronts ◽  
Dynamic Interplay

AbstractThe chromosphere of the quiet Sun is a highly intermittent and dynamic phenomenon. Three-dimensional radiation (magneto-)hydrodynamic simulations exhibit a mesh-like pattern of hot shock fronts and cool expanding post-shock regions in the sub-canopy part of the inter-network. This domain might be called “fluctosphere”. The pattern is produced by propagating shock waves, which are excited at the top of the convection zone and in the photospheric overshoot layer. New high-resolution observations reveal a ubiquitous small-scale pattern of bright structures and dark regions in-between. Although it qualitatively resembles the picture seen in models, more observations – e.g. with the future ALMA – are needed for thorough comparisons with present and future models. Quantitative comparisons demand for synthetic intensity maps and spectra for the three-dimensional (magneto-)hydrodynamic simulations. The necessary radiative transfer calculations, which have to take into account deviations from local thermodynamic equilibrium, are computationally very involved so that no reliable results have been produced so far. Until this task becomes feasible, we have to rely on careful qualitative comparisons of simulations and observations. Here we discuss what effects have to be considered for such a comparison. Nevertheless we are now on the verge of assembling a comprehensive picture of the solar chromosphere in inter-network regions as dynamic interplay of shock waves and structuring and guiding magnetic fields.

scholarly journals Acoustic shock waves in the solar chromosphere from millimeter observations

2006 ◽  
Vol 2 (S233) ◽  
pp. 104 ◽  
Author(s):  
Maria A. Loukitcheva ◽  
Sami K. Solanki ◽  
Stephen White
Keyword(s):  
Shock Waves ◽  
Solar Chromosphere

scholarly journals Wave-driven Mass Loss of Stripped Envelope Massive Stars: Progenitor-dependence, Mass Ejection, and Supernovae

2021 ◽  
Vol 923 (1) ◽  
pp. 41
Author(s):  
Shing-Chi Leung ◽  
Samantha Wu ◽  
Jim Fuller
Keyword(s):  
Wave Energy ◽  
Critical Phenomenon ◽  
Heating Process ◽  
Ejection Process ◽  
Radial Extent ◽  
Cooling Phase ◽  
Stellar Models ◽  
Hydrodynamical Simulations ◽  
Massive Star Evolution ◽  
Mass Ejection

Abstract The discovery of rapidly rising and fading supernovae powered by circumstellar interaction has suggested the pre-supernova mass eruption phase as a critical phenomenon in massive star evolution. It is important to understand the mass and radial extent of the circumstellar medium (CSM) from theoretically predicted mass ejection mechanisms. In this work, we study the wave heating process in massive hydrogen-poor stars, running a suite of stellar models in order to predict the wave energy and pre-explosion timescale of surface energy deposition. We survey stellar models with main-sequence progenitor masses from 20–70 M ⊙ and metallicity from 0.002–0.02. Most of these models predict that less than ∼1047 erg is deposited in the envelope, with the majority of the energy deposited in the last week of stellar evolution. This translates to CSM masses less than ∼10−2 M ⊙ that extend to less than ∼1014 cm, too small to greatly impact the light curves or spectra of the subsequent supernovae, except perhaps during the shock breakout phase. However, a few models predict somewhat higher wave energy fluxes, for which we perform hydrodynamical simulations of the mass ejection process. Radiative transfer simulations of the subsequent supernovae predict a bright but brief shock-cooling phase that could be detected in some Type Ib/c supernovae if they are discovered within a couple days of explosion.

Magnetic Fields and the Supply of Low-frequency Acoustic Wave Energy to the Solar Chromosphere

2019 ◽  
Vol 871 (2) ◽  
pp. 155 ◽  
Author(s):  
S. P. Rajaguru ◽  
C. R. Sangeetha ◽  
Durgesh Tripathi
Keyword(s):  
Magnetic Fields ◽  
Acoustic Wave ◽  
Wave Energy ◽  
Low Frequency ◽  
Solar Chromosphere

Investigation of shock-wave deformation history from recovered structure

1986 ◽  
Vol 44 ◽  
pp. 434-435
Author(s):  
M.A. Mogilevsky ◽  
L.S. Bushnev
Keyword(s):  
Shock Wave ◽  
Plastic Deformation ◽  
Dislocation Density ◽  
Shock Waves ◽  
Shock Front ◽  
Single Crystals ◽  
Residual Deformation ◽  
Deformation Structure ◽  
Deformation History ◽  
Deformation Velocity

Single crystals of Al were loaded by 15 to 40 GPa shock waves at 77 K with a pulse duration of 1.0 to 0.5 μs and a residual deformation of ∼1%. The analysis of deformation structure peculiarities allows the deformation history to be re-established.After a 20 to 40 GPa loading the dislocation density in the recovered samples was about 1010 cm-2. By measuring the thickness of the 40 GPa shock front in Al, a plastic deformation velocity of 1.07 x 108 s-1 is obtained, from where the moving dislocation density at the front is 7 x 1010 cm-2. A very small part of dislocations moves during the whole time of compression, i.e. a total dislocation density at the front must be in excess of this value by one or two orders. Consequently, due to extremely high stresses, at the front there exists a very unstable structure which is rearranged later with a noticeable decrease in dislocation density.

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