Analysis of a longitudinal wave event observed by the Atmospheric Imaging Assembly ( AIA ) onboard the Solar Dynamics Observatory ( SDO ) is presented .
A time sequence of 131 Å 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 \sim 12 min and a decay time of \sim 9 min .
The measured phase speed of 500 \pm 50 km s ^ { -1 } matches the sound speed in the heated loop of \sim 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 ( EUV ) channels , and find that they are nearly in phase .
The measured polytropic index from the temperature and density perturbations is 1.64 \pm 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 .