Modified p-modes in penumbral filaments?

Abstract

Aims: The primary objective of this study is to search for and identify wave modes within a sunspot penumbra. Methods: Infrared spectropolarimetric time series data are inverted using a model comprising two atmospheric components in each spatial pixel. Fourier phase difference analysis is performed on the line-of-sight velocities retrieved from both components to determine time delays between the velocity signals. In addition, the vertical separation between the signals in the two components is calculated from the Stokes velocity response functions. Results: The inversion yields two atmospheric components, one permeated by a nearly horizontal magnetic field, the other with a less-inclined magnetic field. Time delays between the oscillations in the two components in the frequency range 2.5-4.5 mHz are combined with speeds of atmospheric wave modes to determine wave travel distances. These are compared to expected path lengths obtained from response functions of the observed spectral lines in the different atmospheric components. Fast-mode (i.e., modified p-mode) waves exhibit the best agreement with the observations when propagating toward the sunspot at an angle ~50 degrees to the vertical.

8 pages, 12 figures, accepted for publication in Astronomy & Astrophysics

References in corpus (3)

• Fine structure, magnetic field and heating of sunspot penumbrae
• On the fine structure of the sunspot penumbrae. II. The nature of the Evershed flow
• On the fine structure of the sunspot penumbrae. III The vertical extension of penumbral filaments

Cited by in corpus (10)

• Three-dimensional structure of a sunspot light bridge
• Deep probing of the photospheric sunspot penumbra: no evidence for magnetic field-free gaps
• Fine structures in the atmosphere above a sunspot umbra
• Effect of Coronal Loop Structure on Wave Heating by Phase Mixing
• Dependence of sunspot photospheric waves on the depth of the source of solar $p-$modes
• Temporal evolution of small-scale internetwork magnetic fields in the solar photosphere
• Signatures of the impact of flare ejected plasma on the photosphere of a sunspot light-bridge
• Three-lobed near-infrared Stokes V profiles in the quiet Sun
• Long-Term Evolution of Three Light Bridges Developed on the Same Sunspot
• The role of the Lorentz force in sunspot equilibrium