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| Paper: |
Polarimetric Observations of Flare Stars |
| Volume: |
510, Stars: From Collapse to Collapse |
| Page: |
303 |
| Authors: |
Beskin, G.; Karpov, S.; Plokhotnichenko, V.; Stepanov, A.; Tsap, Yu. |
| Abstract: |
Here we present the results of our long-term observations of flaring stars with MANIA high temporal resolution equipment in polarimetric regime. More than forty flares from UV Ceti, EV Lacertae, Wolf 424 and CN Leo have been observed, and upper limits on its polarization have been derived on the level of about 1%, except for the one unique event — the giant flare of UV Ceti in 2008 with the amplitude of about 3 magnitudes in U-band. Near flare maximum more than a dozen of spike bursts have been discovered with sub-second durations and intrinsic polarizations exceeding 30–40%. We argue that these events are synchrotron emission of electron beams with the energies of several hundred MeV moving in the magnetic field of about 1.4 kG. Emission from such ultrarelativistic (with energies far exceeding 10 MeV) particles is being routinely observed in solar flares, but has never been detected from UV Ceti type stars. This is the first ever detection of linearly polarized optical light from the UV Ceti-type stars which indicates that at least some fraction of the flaring events on these stars are powered by a non-thermal synchrotron emission mechanism. |
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