Context :

Aims : We present near ultraviolet ( NUV:1750 - 2800Å ) and far ultraviolet ( FUV : 1350 - 1750Å ) light-curves for flares on 4 nearby dMe-type stars ( GJ 3685A , CR Dra , AF Psc and SDSS J084425.9+513830.5 ) observed with the \it GALEX satellite .

Methods : Taking advantage of the time-tagged events recorded with the \it GALEX photon counting detectors , we present high temporal resolution ( < 0.01 sec ) analysis of these UV flare data .

Results : A statistical analysis of 700 seconds of pre-flare quiescence data for both CR Dra and SDSS J084425.9+513830.5 failed to reveal the presence of significant micro-flare activity in time bins of 0.2 , 1 and 10 second intervals .
Using an appropriate differential emission measure for both the quiescent and flaring state , it is possible to reproduce the observed FUV : NUV flux ratios .
A major determinant in reproducing this flux ratio is found to be the value of plasma electron density during the flare .
We also searched the count rate data recorded during each of the four flare events for periodicity associated with magneto-hydrodynamic oscillations in the active region coronal loops .
Significant oscillations were detected during the flare events observed on all 4 stars , with periodicities found in the 30 to 40 second range .
Flare oscillations with this periodicity can be explained as acoustic waves in a coronal loop of length of \approx 10 ^ { 9 } cm for an assumed plasma temperature of 5 - 20 \times 10 ^ { 6 } K. This suggests a loop length for these M-dwarf flares of less than 1 / 10 ^ { th } of the stellar radii .
We believe that this is the first detection of non-solar coronal loop flare oscillations observed at ultraviolet wavelengths .

Conclusions :