White-light oscillations during a flare on II Peg

Mathioudakis, M.; Seiradakis, J. H.; Williams, David R.; Avgoloupis, S.; Bloomfield, D. Shaun; McAteer, R. T. J.

doi:10.1051/0004-6361:20030394

Cited by 88 publications

(72 citation statements)

References 13 publications

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“…QPP with similar parameters have been detected in stellar flares (see, e.g. Mathioudakis et al 2003;Mitra-Kraev et al 2005, and references therein). Typical periods of QPP are in the range of a few ms to several min.…”

Section: Introductionsupporting

confidence: 54%

Quasi-periodic modulation of solar and stellar flaring emission by magnetohydrodynamic oscillations in a nearby loop

Nakariakov¹,

Foullon²,

Verwichte³

et al. 2006

A&A

173

141

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We propose a new model for quasi-periodic modulation of solar and stellar flaring emission. Fast magnetoacoustic oscillations of a non-flaring loop can interact with a nearby flaring active region. This interaction occurs when part of the oscillation situated outside the loop reaches the regions of steep gradients in magnetic field within an active region and produces periodic variations of electric current density. The modulation depth of these variations is a few orders of magnitude greater than the amplitude of the driving oscillation. The variations of the current can induce current-driven plasma micro-instabilities and thus anomalous resistivity. This can periodically trigger magnetic reconnection, and hence acceleration of charged particles, producing quasi-periodic pulsations of X-ray, optical and radio emission at the arcade footpoints.

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Section: Introductionsupporting

confidence: 54%

Quasi-periodic modulation of solar and stellar flaring emission by magnetohydrodynamic oscillations in a nearby loop

Nakariakov¹,

Foullon²,

Verwichte³

et al. 2006

A&A

173

141

View full text Add to dashboard Cite

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“…They therefore suggest that the QPP in this stellar superflare may be of a similar nature to solar QPP. A well pronounced QPP has been reported during an very energetic flare on the RS CVn binary II Peg (Mathioudakis et al 2003). The QPP has a long period leading to the peak.…”

Section: Introductionmentioning

confidence: 76%

Oscillations in stellar superflares

Balona¹,

Broomhall²,

Kosovichev³

et al. 2015

Monthly Notices of the Royal Astronomical Society

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Two different mechanisms may act to induce quasi-periodic pulsations (QPP) in wholedisk observations of stellar flares. One mechanism may be magneto-hydromagnetic (MHD) forces and other processes acting on flare loops as seen in the Sun. The other mechanism may be forced local acoustic oscillations due to the high-energy particle impulse generated by the flare (known as 'sunquakes' in the Sun). We analyze shortcadence Kepler data of 257 flares in 75 stars to search for QPP in the flare decay branch or post-flare oscillations which may be attributed to either of these two mechanisms. About 18 percent of stellar flares show a distinct bump in the flare decay branch of unknown origin. The bump does not seem to be a highly-damped global oscillation because the periods of the bumps derived from wavelet analysis do not correlate with any stellar parameter. We detected damped oscillations covering several cycles (QPP), in seven flares on five stars. The periods of these oscillations also do not correlate with any stellar parameter, suggesting that these may be a due to flare loop oscillations. We searched for forced global oscillations which might result after a strong flare. To this end, we investigated the behaviour of the amplitudes of solar-like oscillations in eight stars before and after a flare. However, no clear amplitude change could be detected. We also analyzed the amplitudes of the self-excited pulsations in two δ Scuti stars and one γ Doradus star before and after a flare. Again, no clear amplitude changes were found. Our conclusions are that a new process needs to be found to explain the high incidence of bumps in stellar flare light curves, that flare loop oscillations may have been detected in a few stars and that no conclusive evidence exists as yet for flare induced global acoustic oscillations (starquakes).

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“…QPP are also frequently detected in stellar flares, e.g., in wide-band optical wavelengths (e.g., Rodono 1974;Mullan et al 1992;Houdebine et al 1993;Mathioudakis et al 2003Mathioudakis et al , 2006Anfinogentov et al 2013), which are difficult to be detected in the Sun. A systematic study of QPPs in stellar white light flares was recently performed by Balona et al (2015); Pugh et al (2016).…”

Section: Introductionmentioning

confidence: 99%

Comparison of Damped Oscillations in Solar and Stellar X-Ray Flares

Cho

Nakariakov

Kim

et al. 2016

ApJ

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We explore the similarity and difference of the quasi-periodic pulsations (QPPs) observed in the decay phase of solar and stellar flares at X-rays. We identified 42 solar flares with pronounced QPPs, observed with the Reuven Ramaty High-Energy Solar Spectroscopic Imager (RHESSI) and 36 stellar flares with QPPs, observed with X-ray Multi Mirror Newton observatory (XMM-Newton). The Empirical Mode Decomposition (EMD) method and least-square fit by a damped sine function were applied to obtain the periods (P ) and damping times (τ ) of the QPPs. We found that (1) the periods and damping times of the stellar QPPs are 16.21±15.86 min and 27.21±28.73 min, while those of the solar QPPs are 0.90±0.56 and 1.53±1.10 min, respectively. (2) The ratio of the damping times to the periods (τ /P ) observed in the stellar QPPs (1.69±0.56) are statistically identical to those of solar QPPs (1.74±0.77). (3) The scalings of the QPP damping time with the period are well described by the power law in both solar and stellar cases. The power indices of the solar and stellar QPPs are 0.96±0.10 and 0.98±0.05, respectively. This scaling is consistent with the scalings found for standing slow magnetoacoustic and kink modes in solar coronal loops. Thus, we propose that the underlying mechanism responsible for the stellar QPPs is the natural magnetohydrodynamic oscillations in the flaring or adjacent coronal loops, as in the case of solar flares.

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White-light oscillations during a flare on II Peg

Cited by 88 publications

References 13 publications

Quasi-periodic modulation of solar and stellar flaring emission by magnetohydrodynamic oscillations in a nearby loop

Quasi-periodic modulation of solar and stellar flaring emission by magnetohydrodynamic oscillations in a nearby loop

Oscillations in stellar superflares

Comparison of Damped Oscillations in Solar and Stellar X-Ray Flares

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