The solar f-mode as an interfacial mode at the chromosphere-corona transition

Rosenthal, C. S.; Gough, D. O.

doi:10.1086/173826

Cited by 36 publications

(13 citation statements)

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“…However, observations (Fernandes et al 1992;Duvall et al 1998) revealed significant deviations of the frequencies of the solar f -modes from the simple relation given in Eq. (17), so their diagnostic importance grew significantly (Rosenthal & Gough 1994;Rosenthal & Christensen-Dalsgaard 1995;Ghosh et al 1995;Mȩdrek et al 1999;Murawski 2000a,b). Attempts were made to explain the frequency shifts of the high spherical harmonic degree solar f -modes by considering them as interfacial waves, which propagate at the chromosphere-corona transition (Rosenthal & Gough 1994;Rosenthal & Christensen-Dalsgaard 1995).…”

Section: F -Modementioning

confidence: 99%

“…(17), so their diagnostic importance grew significantly (Rosenthal & Gough 1994;Rosenthal & Christensen-Dalsgaard 1995;Ghosh et al 1995;Mȩdrek et al 1999;Murawski 2000a,b). Attempts were made to explain the frequency shifts of the high spherical harmonic degree solar f -modes by considering them as interfacial waves, which propagate at the chromosphere-corona transition (Rosenthal & Gough 1994;Rosenthal & Christensen-Dalsgaard 1995). The other hypothesis mentioned earlier invokes frequency shifts and line broadening of the f -mode due to the turbulent motions (Murawski & Roberts 1993a,b;Mȩdrek et al 1999;Murawski 2000a,b).…”

Section: F -Modementioning

confidence: 99%

“…9(a) and show a linearly decreasing trend with kx, indicated by the red line with slope ∼ −0.01. However, such kx-dependent frequency shifts of the f -mode are expected both from the influence of turbulent motions (Mȩdrek et al 1999;Murawski 2000a,b;Mole et al 2008, where shifts are linear in k), as well as for interfacial waves propagating in the transition region between chromosphere and corona (Rosenthal & Gough 1994;Rosenthal & Christensen-Dalsgaard 1995). By comparison, purely viscous effects proportional to νk 2 would yield a relative frequency shift δω 2 /ω 2 ≈ 2νk 3/2 x / √ g, which is around 10 −3 for kx = 10.…”

Section: F -Modementioning

confidence: 99%

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Properties of p and f modes in hydromagnetic turbulence

Singh

Brandenburg

Chitre

et al. 2015

Monthly Notices of the Royal Astronomical Society

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With the ultimate aim of using the fundamental or f -mode to study helioseismic aspects of turbulence-generated magnetic flux concentrations, we use randomly forced hydromagnetic simulations of a piecewise isothermal layer in two dimensions with reflecting boundaries at top and bottom. We compute numerically diagnostic wavenumber-frequency diagrams of the vertical velocity at the interface between the denser gas below and the less dense gas above. For an Alfvén-to-sound speed ratio of about 0.1, a 5% frequency increase of the f -mode can be measured when k x H p = 3-4, where k x is the horizontal wavenumber and H p is the pressure scale height at the surface. Since the solar radius is about 2000 times larger than H p , the corresponding spherical harmonic degree would be 6000-8000. For weaker fields, a k x -dependent frequency decrease by the turbulent motions becomes dominant. For vertical magnetic fields, the frequency is enhanced for k x H p ≈ 4, but decreased relative to its nonmagnetic value for k x H p ≈ 9.

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Section: F -Modementioning

confidence: 99%

Section: F -Modementioning

confidence: 99%

Section: F -Modementioning

confidence: 99%

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Properties of p and f modes in hydromagnetic turbulence

Singh

Brandenburg

Chitre

et al. 2015

Monthly Notices of the Royal Astronomical Society

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“…Secondly, mode coupling between the identified modes and some invisible modes [such as modes with high spherical degree ℓ, or interfacial modes (Rosenthal & Gough 1994)] can also quite securely be discarded on the following grounds. The participation of every single mode in a resonant process is unlikely, because mode coupling is supposedly a rare phenomenon that requires specific resonant conditions.…”

Section: The 1985 Eventmentioning

confidence: 99%

Non-linear behaviour of the pulsating white dwarf G29-38 — I. Evolution of the temporal spectrum

Vuille

2000

Monthly Notices of the Royal Astronomical Society

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An analysis of the evolution of the amplitude spectrum over many seasons of the DA pulsating white dwarf G29‐38 has been performed. Neither beating nor resonant mode coupling can account for the observed appearance and disappearance of modes, although some of them clearly grow while others get damped. Therefore some unknown non‐adiabatic, non‐linear process has to be invoked that affects both the mode selection mechanism and the driving efficiency on a time‐scale as short as a day.

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“…For simplicity, initially we shall focus on the f mode. The solar f mode is usually taken to be an incompressible, buoyancy-driven oscillation confined to the near-surface photospheric region (although Rosenthal and Gough (1994) and Rosenthal and Christensen-Dalsgaard (1995) proposed an alternative explanation as an interfacial mode at the chromospherecorona transition).…”

Section: Introductionmentioning

confidence: 99%

Effects of Random Flows on the Solar f Mode: I. Horizontal Flow

2008

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We examine the effect of random horizontal flows on the dispersion relation of high-degree solar f modes. We follow the approach of Murawski and Roberts (Astron. Astrophys. 272, 595, 1993), addressing some limitations of that paper, and extending the results to include damping and to apply for a general turbulent spectrum. We find a reduction in frequency below the classical result that is about three times that observed. For large wavenumber the damping rate is larger than the frequency correction by a factor of the order of the nondimensional wavenumber, which appears to be consistent with observation.

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The solar f-mode as an interfacial mode at the chromosphere-corona transition

Cited by 36 publications

References 0 publications

Properties of p and f modes in hydromagnetic turbulence

Properties of p and f modes in hydromagnetic turbulence

Non-linear behaviour of the pulsating white dwarf G29-38 — I. Evolution of the temporal spectrum

Effects of Random Flows on the Solar f Mode: I. Horizontal Flow

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