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arXiv · 2206.08070

Doubling of minute-long Quasi-Periodic Pulsations from super-flares on a low mass star

J. Gerry Doyle·Puji Irawati·Dmitrii Y. Kolotkov·Gavin Ramsay·Nived Vilangot Nhalil·Vik S. Dhillon·Tom R. Marsh·Ram Kesh Yadav
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Abstract

Using the ULTRASPEC instrument mounted on the 2.4-m Thai National Telescope, we observed two large flares, each with a total energy close to 10^34 erg with sub-second cadence. A combination of a wavelet analysis, a Fourier transform plus an empirical mode decomposition, reveals quasi-period pulsations (QPP) which exhibit an apparent doubling of the oscillation period. Both events showed oscillations of a few minutes over a interval of several minutes, and despite the availability of sub-second cadence, there was no evidence of sub-minute oscillations. The doubling of the QPP periods and shorter lifetime of shorter-period QPP modes strongly favour resonant dynamics of magnetohydrodynamic waves in a coronal loop. We estimate loop lengths to be 0.2-0.7 R*, in agreement with a typical length of solar coronal loops. These observations presents rare and compelling evidence for the presence of compact plasma loops in a stellar corona.

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J. Gerry Doyle, Puji Irawati, Dmitrii Y. Kolotkov, Gavin Ramsay, Nived Vilangot Nhalil, Vik S. Dhillon, Tom R. Marsh, Ram Kesh Yadav. 2022-06-16. Doubling of minute-long Quasi-Periodic Pulsations from super-flares on a low mass star. https://doi.org/10.1093/mnras%2Fstac1695

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