Waves in Solar Coronal Loops

Wang, Tongjiang

doi:10.1002/9781119055006.ch23

Cited by 48 publications

(18 citation statements)

References 239 publications

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“…One promising indirect method for obtaining information about the coronal magnetic field is magnetohydrodynamic (MHD) seismology, based on the estimation of the coronal Alfvén speed (e.g. Nakariakov & Ofman 2001;Liu & Ofman 2014;Wang 2016). Similar plasma diagnostic techniques are used in laboratory plasma and Earth's magnetospheric research (e.g., Fasoli et al 2002;Nakariakov et al 2016b, respectively).…”

Section: Introductionmentioning

confidence: 99%

Magnetohydrodynamic Seismology of Quiet Solar Active Regions

Anfinogentov

Nakariakov

2019

ApJL

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The ubiquity of recently discovered low-amplitude decayless kink oscillations of plasma loops allows for the seismological probing of the corona on a regular basis. In particular, in contrast to traditionally applied seismology which is based on the large-amplitude decaying kink oscillations excited by flares and eruptions, decayless oscillations can potentially provide the diagnostics necessary for their forecasting. We analysed decayless kink oscillations in several distinct loops belonging to active region NOAA 12107 on 10 July 2010 during its quiet time period, when it was observed on the West limb in EUV by the Atmospheric Imaging Assembly on-board Solar Dynamics Observatory. The oscillation periods were estimated with the use of the motion magnification technique. The lengths of the oscillating loops were determined within the assumption of its semicircular shape by measuring the position of their foot-points. The density contrast in the loops was estimated from the observed intensity contrast accounting for the unknown spatial scale of the background plasma. The combination of those measurements allows us to determine the distribution of kink and Alfvén speeds in the active region. Thus, we demonstrate the possibility to obtain seismological information about coronal active regions during the quiet periods of time.

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Section: Introductionmentioning

confidence: 99%

Magnetohydrodynamic Seismology of Quiet Solar Active Regions

Anfinogentov

Nakariakov

2019

ApJL

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“…In this case, the pulsations could reveal fundamental properties of the energy release process itself. The second possibility is that the pulsations arise from MHD waves propagating in magnetic loops (Edwin & Roberts 1983;Nakariakov & Verwichte 2005;Wang 2016). Their characteristics would depend on the type of MHD waves (e.g.…”

Section: Introductionmentioning

confidence: 99%

Detection and Interpretation of Long-lived X-Ray Quasi-periodic Pulsations in the X-class Solar Flare on 2013 May 14

Dennis

Tolbert

Inglis

et al. 2017

ApJ

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Quasi-periodic pulsations (QPP) seen in the time derivative of the GOES soft X-ray light curves are analyzed for the near-limb X3.2 event on 14 May 2013. The pulsations are apparent for a total of at least two hours from the impulsive phase to well into the decay phase, with a total of 163 distinct pulses evident to the naked eye. A wavelet analysis shows that the characteristic time scale of these pulsations increases systematically from ∼25 s at 01:10 UT, the time of the GOES peak, to ∼100 s at 02:00 UT. A second 'ridge' in the wavelet power spectrum, most likely associated with flaring emission from a different active region, shows an increase from ∼40 s at 01:40 UT to ∼100 s at 03:10 UT. We assume that the QPP that produced the first ridge result from vertical kink-mode oscillations of the newly formed loops following magnetic reconnection in the coronal current sheet. This allows us to estimate the magnetic field strength as a function of altitude given the density, loop length, and QPP time scale as functions of time determined from the GOES light curves and RHESSI images. The calculated magnetic field strength of the newly formed loops ranges from ∼500 G at an altitude of 24 Mm to a low value of ∼10 G at 60 Mm, in general agreement with the expected values at these altitudes. Fast sausage mode oscillations are also discussed and cannot be ruled out as an alternate mechanism for producing the QPP.

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“…Waves and oscillations in the magnetohydrodynamic (MHD) regime have been abundantly observed in the highly structured solar atmosphere (see e.g., Nakariakov & Verwichte 2005;Banerjee et al 2007;De Moortel & Nakariakov 2012;Wang 2016, for recent reviews). Apart from being important agents for atmospheric heating (see e.g., Klimchuk 2006;Parnell & De Moortel 2012;Arregui 2015;De Moortel & Browning 2015, for some recent reviews), these waves and oscillations can also be exploited in the context of solar magneto-seismology (SMS) to infer the atmospheric parameters that are difficult to directly measure (for early ideas that laid the foundation of this practice, see Uchida 1970, Rosenberg 1970, Zajtsev & Stepanov 1975, Roberts et al 1984; also see recent reviews by e.g., Nakariakov & Verwichte 2005, Roberts 2008, Erdélyi & Goossens 2011, Nakariakov et al 2016.…”

Section: Introductionmentioning

confidence: 99%

Impulsively Generated Wave Trains in Coronal Structures. I. Effects of Transverse Structuring on Sausage Waves in Pressureless Tubes

Chen

et al. 2017

ApJ

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The behavior of the axial group speeds of trapped sausage modes plays an important role in determining impulsively generated wave trains, which have often been invoked to account for quasi-periodic signals with quasi-periods of order seconds in a considerable number of coronal structures. We conduct a comprehensive eigenmode analysis, both analytically and numerically, on the dispersive properties of sausage modes in pressureless tubes with three families of continuous radial density profiles. We find a rich variety of the dependence on the axial wavenumber k of the axial group speed v gr . Depending on the density contrast and profile steepness as well as on the detailed profile description, the v gr − k curves either possess or do not possess cutoff wavenumbers, and they can behave in either a monotonical or non-monotonical manner. With time-dependent simulations, we further show that this rich variety of the group speed characteristics heavily influences the temporal evolution and Morlet spectra of impulsively -2 -generated wave trains. In particular, the Morlet spectra can look substantially different from "crazy tadpoles" found for the much-studied discontinuous density profiles. We conclude that it is necessary to re-examine available high-cadence data to look for the rich set of temporal and spectral features, which can be employed to discriminate between the unknown forms of the density distributions transverse to coronal structures.

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Waves in Solar Coronal Loops

Cited by 48 publications

References 239 publications

Magnetohydrodynamic Seismology of Quiet Solar Active Regions

Magnetohydrodynamic Seismology of Quiet Solar Active Regions

Detection and Interpretation of Long-lived X-Ray Quasi-periodic Pulsations in the X-class Solar Flare on 2013 May 14

Impulsively Generated Wave Trains in Coronal Structures. I. Effects of Transverse Structuring on Sausage Waves in Pressureless Tubes

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