We report on multi-wavelength observations spanning radio to X-ray wavelengths of the M dwarf flare star , EV Lacertae , probing the characteristics of the outer atmospheric plasma from the upper chromosphere to the corona .
We detect the star at a wavelength of 2 cm ( 15 GHz ) for the first time .
UV and FUV line profiles show evidence of nonthermal broadening , and the velocity width appear to peak at lower temperatures than in the Sun ; this trend is confirmed in another active M dwarf flare star .
Electron density measurements indicate nearly constant electron pressures between \log T = 5.2 and 6.4 .
At higher coronal temperatures , there is a sharp increase of two orders of magnitude in density ( n _ { e } \sim 10 ^ { 13 } cm ^ { -3 } at \log T = 6.9 ) .
X-ray , EUV , FUV and NUV spectra constrain the DEM from the upper chromosphere through the corona .
The coronal pressures are inconsistent with the assumption of hydrostatic equilibrium , either through EM modeling or application of scaling laws , and imply large conductive loss rates and a large energy input at the highest temperatures .
The timescales for radiative and conductive losses in EV Lac ’ s upper atmosphere imply that significant continued heating must occur for the corona to maintain its quiescent properties .
The high frequency radio detection requires the high temperature X-ray-emitting coronal plasma to be spatially distinct from the radio emission source .
Length scales in the low-temperature corona are markedly larger than those in the high-temperature corona , further suggestions of an inhomogeneous mixture of thermal and nonthermal coronal plasma .