Diagnostics of a flare on EQ Peg B from optical pulsations |
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Authors: | Yu T Tsap A V Stepanov Yu G Kopylova B E Zhilyaev |
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Institution: | 1.Crimean Astrophysical Observatory (CrAO),Crimea,Ukraine;2.Pulkovo Astronomical Observatory,Russian Academy of Sciences,Pulkovo, St. Petersburg,Russia;3.Main Astronomical Observatory,National Academy of Sciences of Ukraine,Kiev,Ukraine |
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Abstract: | Based on the methods of coronal seismology, we have investigated the ten-second quasi-periodic pulsations of the optical flare
emission from the active red dwarf EQ Peg B detected with the William Herschel Telescope on La Palma. We propose and analyze
a model in which they could be produced by sausage oscillations of a coronal flare loop. The amplitude and phase relations
between the displacement components of the radial oscillations and the conditions for their excitation in loops with footpoints
frozen into the photosphere are considered. The temperature (≈6 × 107 K), plasma density (≈2.7 × 1011 cm−3), and magnetic field strength (≈540 G) in the region of energy release have been determined. Our estimate of the flare loop
length (≈0.4R
⋆) provides evidence for the existence of extended coronae on red dwarf stars. |
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