First dynamic spectra of stellar microwave flares

The authors have used the Very Large Array in spectral-line mode at 1.4 GHz to obtain dynamic spectra of stellar sources other than the Sun. Two very intense, highly circularly polarized, microwave outbursts were observed on the dMe flare star UV Cet (L726-8B), in addition to a slowly varying, unpolarized component. One outburst was purely left circularly polarized and showed no variations as a function of frequency across the 41 MHz band, whereas the other was as much as 70% right-circularly polarized and showed distinct variations with frequency. Although the slowly varying emission is probably due to incoherent gyrosynchrotron emission, the two flaring events are the result of coherent mechanisms. (author)