Ideal Monatomic Gas

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L Ofman - One of the best experts on this subject based on the ideXlab platform.

  • evidence of thermal conduction suppression in a solar flaring loop by coronal seismology of slow mode waves
    The Astrophysical Journal, 2015
    Co-Authors: Tongjiang Wang, L Ofman, Xudong Sun, Elena Provornikova, Joseph M Davila
    Abstract:

    Analysis of a longitudinal wave event observed by the Atmospheric Imaging Assembly (AIA) onboard the Solar Dynamics Observatory is presented. A time sequence of 131 A images reveals that a C-class flare occurred at one footpoint of a large loop and triggered an intensity disturbance (enhancement) propagating along it. The spatial features and temporal evolution suggest that a fundamental standing slow-mode wave could be set up quickly after meeting of two initial disturbances from the opposite footpoints. The oscillations have a period of ~12 minutes and a decay time of ~9 minutes. The measured phase speed of 500 ± 50 km s−1 matches the sound speed in the heated loop of ~10 MK, confirming that the observed waves are of slow mode. We derive the time-dependent temperature and electron density wave signals from six AIA extreme-ultraviolet channels, and find that they are nearly in phase. The measured polytropic index from the temperature and density perturbations is 1.64 ± 0.08 close to the adiabatic index of 5/3 for an Ideal Monatomic Gas. The interpretation based on a 1D linear MHD model suggests that the thermal conductivity is suppressed by at least a factor of 3 in the hot flare loop at 9 MK and above. The viscosity coefficient is determined by coronal seismology from the observed wave when only considering the compressive viscosity dissipation. We find that to interpret the rapid wave damping, the classical compressive viscosity coefficient needs to be enhanced by a factor of 15 as the upper limit.

Tongjiang Wang - One of the best experts on this subject based on the ideXlab platform.

  • evidence of thermal conduction suppression in a solar flaring loop by coronal seismology of slow mode waves
    The Astrophysical Journal, 2015
    Co-Authors: Tongjiang Wang, L Ofman, Xudong Sun, Elena Provornikova, Joseph M Davila
    Abstract:

    Analysis of a longitudinal wave event observed by the Atmospheric Imaging Assembly (AIA) onboard the Solar Dynamics Observatory is presented. A time sequence of 131 A images reveals that a C-class flare occurred at one footpoint of a large loop and triggered an intensity disturbance (enhancement) propagating along it. The spatial features and temporal evolution suggest that a fundamental standing slow-mode wave could be set up quickly after meeting of two initial disturbances from the opposite footpoints. The oscillations have a period of ~12 minutes and a decay time of ~9 minutes. The measured phase speed of 500 ± 50 km s−1 matches the sound speed in the heated loop of ~10 MK, confirming that the observed waves are of slow mode. We derive the time-dependent temperature and electron density wave signals from six AIA extreme-ultraviolet channels, and find that they are nearly in phase. The measured polytropic index from the temperature and density perturbations is 1.64 ± 0.08 close to the adiabatic index of 5/3 for an Ideal Monatomic Gas. The interpretation based on a 1D linear MHD model suggests that the thermal conductivity is suppressed by at least a factor of 3 in the hot flare loop at 9 MK and above. The viscosity coefficient is determined by coronal seismology from the observed wave when only considering the compressive viscosity dissipation. We find that to interpret the rapid wave damping, the classical compressive viscosity coefficient needs to be enhanced by a factor of 15 as the upper limit.

Joseph M Davila - One of the best experts on this subject based on the ideXlab platform.

  • evidence of thermal conduction suppression in a solar flaring loop by coronal seismology of slow mode waves
    The Astrophysical Journal, 2015
    Co-Authors: Tongjiang Wang, L Ofman, Xudong Sun, Elena Provornikova, Joseph M Davila
    Abstract:

    Analysis of a longitudinal wave event observed by the Atmospheric Imaging Assembly (AIA) onboard the Solar Dynamics Observatory is presented. A time sequence of 131 A images reveals that a C-class flare occurred at one footpoint of a large loop and triggered an intensity disturbance (enhancement) propagating along it. The spatial features and temporal evolution suggest that a fundamental standing slow-mode wave could be set up quickly after meeting of two initial disturbances from the opposite footpoints. The oscillations have a period of ~12 minutes and a decay time of ~9 minutes. The measured phase speed of 500 ± 50 km s−1 matches the sound speed in the heated loop of ~10 MK, confirming that the observed waves are of slow mode. We derive the time-dependent temperature and electron density wave signals from six AIA extreme-ultraviolet channels, and find that they are nearly in phase. The measured polytropic index from the temperature and density perturbations is 1.64 ± 0.08 close to the adiabatic index of 5/3 for an Ideal Monatomic Gas. The interpretation based on a 1D linear MHD model suggests that the thermal conductivity is suppressed by at least a factor of 3 in the hot flare loop at 9 MK and above. The viscosity coefficient is determined by coronal seismology from the observed wave when only considering the compressive viscosity dissipation. We find that to interpret the rapid wave damping, the classical compressive viscosity coefficient needs to be enhanced by a factor of 15 as the upper limit.

Elena Provornikova - One of the best experts on this subject based on the ideXlab platform.

  • evidence of thermal conduction suppression in a solar flaring loop by coronal seismology of slow mode waves
    The Astrophysical Journal, 2015
    Co-Authors: Tongjiang Wang, L Ofman, Xudong Sun, Elena Provornikova, Joseph M Davila
    Abstract:

    Analysis of a longitudinal wave event observed by the Atmospheric Imaging Assembly (AIA) onboard the Solar Dynamics Observatory is presented. A time sequence of 131 A images reveals that a C-class flare occurred at one footpoint of a large loop and triggered an intensity disturbance (enhancement) propagating along it. The spatial features and temporal evolution suggest that a fundamental standing slow-mode wave could be set up quickly after meeting of two initial disturbances from the opposite footpoints. The oscillations have a period of ~12 minutes and a decay time of ~9 minutes. The measured phase speed of 500 ± 50 km s−1 matches the sound speed in the heated loop of ~10 MK, confirming that the observed waves are of slow mode. We derive the time-dependent temperature and electron density wave signals from six AIA extreme-ultraviolet channels, and find that they are nearly in phase. The measured polytropic index from the temperature and density perturbations is 1.64 ± 0.08 close to the adiabatic index of 5/3 for an Ideal Monatomic Gas. The interpretation based on a 1D linear MHD model suggests that the thermal conductivity is suppressed by at least a factor of 3 in the hot flare loop at 9 MK and above. The viscosity coefficient is determined by coronal seismology from the observed wave when only considering the compressive viscosity dissipation. We find that to interpret the rapid wave damping, the classical compressive viscosity coefficient needs to be enhanced by a factor of 15 as the upper limit.

Jeffrey S Urbach - One of the best experts on this subject based on the ideXlab platform.

  • steady base states for navier stokes granular hydrodynamics with boundary heating and shear
    Journal of Fluid Mechanics, 2009
    Co-Authors: Francisco Vega Reyes, Jeffrey S Urbach
    Abstract:

    We study the Navier-Stokes steady states for a low density monodisperse hard sphere granular Gas (i.e a hard sphere Ideal Monatomic Gas with inelastic inter-particle collisions). We present a classification of the uniform steady states that can arise from shear and temperature (or energy input) applied at the boundaries (parallel walls). We consider both symmetric and asymmetric boundary conditions and find steady states not previously reported, including sheared states with linear temperature profiles. We provide explicit expressions for the hydrodynamic profiles for all these steady states. Our results are validated by the numerical solution of the Boltzmann kinetic equation for the granular Gas obtained by the direct simulation Monte Carlo method, and by molecular dynamics simulations. We discuss the physical origin of the new steady states and derive conditions for the validity of Navier-Stokes hydrodynamics.