On the Theory of Coronal Heating Mechanisms

Kuperus, M.; Ionson, J. A.; Spicer, D. S.

doi:10.1146/annurev.aa.19.090181.000255

Cited by 164 publications

(76 citation statements)

References 21 publications

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“…Kuperus et al 1981;Parker 1994;Walsh and Ireland 2003), 2Mm and more above the visible solar surface. At a first glance, this seems odd, since the corona is a tenuous structure fed by mass, momentum and energy from below.…”

Section: Introductionmentioning

confidence: 99%

The Connection of Type Ii Spicules to the Corona

Judge

Pontieu

McIntosh

et al. 2012

ApJ

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We examine the hypothesis that plasma associated with "Type II" spicules is heated to coronal temperatures, and that the upward moving hot plasma constitutes a significant mass supply to the solar corona. 1D hydrodynamical models including timedependent ionization are brought to bear on the problem. These calculations indicate that heating of field-aligned spicule flows should produce significant differential Doppler shifts between emission lines formed in the chromosphere, transition region, and corona. At present, observational evidence for the computed 60-90 km s −1 differential shifts is weak, but the data are limited by difficulties in comparing the proper motion of Type-II spicules, with spectral and kinematic properties of associated transition region and coronal emission lines. Future observations with the upcoming IRIS instrument should clarify if Doppler shifts are consistent with the dynamics modeled here.

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Section: Introductionmentioning

confidence: 99%

The Connection of Type Ii Spicules to the Corona

Judge

Pontieu

McIntosh

et al. 2012

ApJ

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“…At the magnetic surface where the frequency of the inciding wave equals the local Alfvén frequency, a resonant Alfvén wave can be excited. The resonant peak resulting from this energy transfer supplies the small lengthscales necessary for dissipation to become effective (Kuperus et al 1981;Goossens 1991). Numerical results reveal that sideways excitation is most efficient when the loop is driven at the frequency of a fast eigenmode, lying inside the Alfvén continuum, a so-called "quasi-mode" (Poedts et al 1989;Poedts & Kerner 1992;Steinolfson & Davila 1993;Ofman & Davila 1995;Ofman & Davila 1996;Wright & Rickard 1995).…”

Section: Introductionmentioning

confidence: 99%

Fast and Alfvén waves driven by azimuthal footpoint motions

Groof

Paes

Goossens

2002

A&A

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Abstract. The excitation of Alfvén and fast magneto-acoustic waves in coronal loops driven by footpoint motions is studied in linear, ideal MHD. The analysis is restricted to azimuthally polarized footpoint motions so that only Alfvén waves are directly excited which couple to fast magneto-acoustic waves at later times. In the present study a periodic driver is applied at one end of the loop. The effects of a more realistic random driver are studied in the companion paper De Groof & Goossens (2002) (hereafter referred to as Paper II). The first part of the paper is devoted to the study of resonant absorption and phase-mixing in the absence of coupling (azimuthal wavenumber ky = 0). Since the density varies across the loop, resonances occur at the magnetic surfaces where the driving frequency equals the local Alfvén frequency. In a second part where Alfvén waves with ky = 0 coupling to fast waves are taken into account, we find that the behaviour of the MHD waves is strongly dependent on the driving frequency ω d . Especially driving frequencies equal to a quasi-mode frequency seem to make the difference. The fast waves excited in these cases are global oscillations of the system and form quasi-modes as they are damped through the resonant coupling with Alfvén modes. Since these resonances occur at the same location where the original Alfvén wave peaks, the resonant peak is further amplified. While in most cases coupling has a negative effect on the growth of the directly excited Alfvén waves, driving with a quasi-mode frequency leads to a faster growth of the resonant peaks and a more efficient decrease in length scales than in the uncoupled case.

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“…Winding up of magnetic flux tubes in pole-pole or pole-spot connections, due to differential rotation builds up currents in the corona (Sakurai 1979, and heating is expected as a result of their dissipation (cf. Kuperus et al 1981). An alternative mechanism is due to the interaction between pole-pole and pole-spot connection which execute a different mode of motion.…”

Section: Heating Of the Coronamentioning

confidence: 99%

Interacting Magnetospheres in RS CVn Binaries – Coronal Heating and Flares

Uchida

Sakurai

1983

International Astronomical Union Colloquium

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Coronae and flares of RS CVn systems are interpreted as due to gradual and sudden releases of magnetic free energy which is built up throught the interaction of magnetic fields of stars in these close binary systems. X RAY AND RADIO OBSERVATIONSRecent observations of RS CVn binaries in soft X-rays (Walter et al 1980) and in radio wavelengths (Gibson et al 1978, Feldman et al 1978 indicate the presence of vigorous coronae and the occurrence of flares. These, combined with the starspot hypothesis based on the "Photometric Wave" (PW) in the light curves (Hall 1972, Eaton andHall 1979), strongly suggest that these high temperature or high energy phenomena may be due to activated magnetic fields in the outer atmospheres of the component stars, as already found in the case of the Sun (e.g., Sheeley et al 1974, Sakurai and. In the present paper, we look into this possibility by examining the magnetic field configuration and various distorting effects. ACTIVE-LONGITUDE-BELT MODELIn presenting our argument we first introduce a new aspect into the starspot hypothesis. We propose that the PW may correspond to the stellar analogue, in an extreme form, of an "Active-Longitude-Belt" on the Sun (ALB) in which active spot-groups are seen to emerge, drift across and disappear, rather than being due to a gigantic, long-lived starspot, or aggregate of spots. Introduction of the notion of an ALB relieves us of the somewhat unnatural, though very fascinating, assumption of a gigantic spot or aggregate of spots, staying almost fixed on 629 [629][630][631][632] P. B. Byrne and M. Rodond feds.), Activity in

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On the Theory of Coronal Heating Mechanisms

Cited by 164 publications

References 21 publications

The Connection of Type Ii Spicules to the Corona

The Connection of Type Ii Spicules to the Corona

Fast and Alfvén waves driven by azimuthal footpoint motions

Interacting Magnetospheres in RS CVn Binaries – Coronal Heating and Flares

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