3D simulations of realistic power halos in magnetohydrostatic sunspot atmospheres

linking theory and observation

Carlos Rijs, S. P. Rajaguru, Damien Przybylski, Hamed Moradi, Paul Cally, Sergiy Shelyag

Research output: Contribution to journalArticleResearchpeer-review

9 Citations (Scopus)

Abstract

The well-observed acoustic halo is an enhancement in time-averaged Doppler velocity and intensity power with respect to quiet-Sun values that is prominent for the weak and highly inclined field around the penumbra of sunspots and active regions. We perform 3D linear wave modeling with realistic distributed acoustic sources in a magnetohydrostatic sunspot atmosphere and compare the resultant simulation enhancements with multiheight SDO observations of the phenomenon. We find that simulated halos are in good qualitative agreement with observations. We also provide further proof that the underlying process responsible for the halo is the refraction and return of fast magnetic waves that have undergone mode conversion at the critical a = c atmospheric layer. In addition, we also find strong evidence that fast Alfvén mode conversion plays a significant role in the structure of the halo, taking energy away from photospheric and chromospheric heights in the form of field-aligned Alfvén waves. This conversion process may explain the observed "dual-ring" halo structure at higher (>8 mHz) frequencies.

Original languageEnglish
Article number45
Number of pages13
JournalThe Astrophysical Journal
Volume817
Issue number1
DOIs
Publication statusPublished - 20 Jan 2016

Keywords

  • Sun: chromosphere
  • Sun: magnetic fields
  • Sun: oscillations
  • Sun: photosphere
  • sunspots

Cite this

Rijs, Carlos ; Rajaguru, S. P. ; Przybylski, Damien ; Moradi, Hamed ; Cally, Paul ; Shelyag, Sergiy. / 3D simulations of realistic power halos in magnetohydrostatic sunspot atmospheres : linking theory and observation. In: The Astrophysical Journal. 2016 ; Vol. 817, No. 1.
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abstract = "The well-observed acoustic halo is an enhancement in time-averaged Doppler velocity and intensity power with respect to quiet-Sun values that is prominent for the weak and highly inclined field around the penumbra of sunspots and active regions. We perform 3D linear wave modeling with realistic distributed acoustic sources in a magnetohydrostatic sunspot atmosphere and compare the resultant simulation enhancements with multiheight SDO observations of the phenomenon. We find that simulated halos are in good qualitative agreement with observations. We also provide further proof that the underlying process responsible for the halo is the refraction and return of fast magnetic waves that have undergone mode conversion at the critical a = c atmospheric layer. In addition, we also find strong evidence that fast Alfv{\'e}n mode conversion plays a significant role in the structure of the halo, taking energy away from photospheric and chromospheric heights in the form of field-aligned Alfv{\'e}n waves. This conversion process may explain the observed {"}dual-ring{"} halo structure at higher (>8 mHz) frequencies.",
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3D simulations of realistic power halos in magnetohydrostatic sunspot atmospheres : linking theory and observation. / Rijs, Carlos; Rajaguru, S. P.; Przybylski, Damien; Moradi, Hamed; Cally, Paul; Shelyag, Sergiy.

In: The Astrophysical Journal, Vol. 817, No. 1, 45, 20.01.2016.

Research output: Contribution to journalArticleResearchpeer-review

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T1 - 3D simulations of realistic power halos in magnetohydrostatic sunspot atmospheres

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AU - Rijs, Carlos

AU - Rajaguru, S. P.

AU - Przybylski, Damien

AU - Moradi, Hamed

AU - Cally, Paul

AU - Shelyag, Sergiy

PY - 2016/1/20

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