Soft X-ray oscillations from AT Mic: Flare plasma diagnostics |
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| Authors: | A V Stepanov Yu T Tsap Yu G Kopylova |
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| Institution: | (1) Pulkovo Astronomical Observatory, Russian Academy of Sciences, Pulkovo, St. Petersburg, 196140, Russia;(2) Crimean Astrophysical Observatory, p/o Nauchnyi, 334413 Crimea, Ukraine |
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| Abstract: | We consider the flare oscillations from the active red dwarf AT Mic detected with the XMM-Newton space observatory in the soft X-ray energy range (0.2–12 keV). Following Mitra-Kraev et al. (2005a), we associate the observed oscillations with a period of ≈750 s with the excitation of a standing slow magnetoacoustic (SMA) wave in a coronal loop. The damping of flare loop SMA oscillations is shown to be governed by electron thermal conduction. We have estimated the plasma density (≈3 × 1010 cm?3) and the minimum magnetic field strength (≈100 G) in the region of flare energy release. The adopted model is consistent with the results of a spectral analysis of the soft X-ray emission. The piston mechanism is assumed to be responsible for the excitation of loop SMA oscillations. |
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