Space-Time Distribution of G-Band and Ca II H-Line Intensity Oscillations in Hinode/SOT-FG Observations

TL;DR

This study analyzes high-resolution Hinode/SOT-FG observations to reveal a mesh pattern of oscillatory power in the solar photosphere and chromosphere, showing how magnetic fields influence oscillations at different frequencies.

Contribution

It uncovers a large-scale mesh pattern of oscillation power in the solar atmosphere and links it to convection cell sizes and turbulence, advancing understanding of solar dynamics.

Findings

Oscillations at 5.5-8.0 mHz are suppressed by magnetic fields.

A 2-3 Mm mesh pattern of oscillatory power is observed.

The mesh pattern correlates with stable convection cells.

Abstract

We study the space-time distributions of intensity fluctuations in 2 - 3 hour sequences of multi-spectral, high-resolution, high-cadence broad-band filtergram images (BFI) made by the SOT-FG system aboard the Hinode spacecraft. In the frequency range 5.5 < f < 8.0 mHz both G-band and Ca II H-line oscillations are suppressed in the presence of magnetic fields, but the suppression disappears for f > 10 mHz. By looking at G-band frequencies above 10 mHz we find that the oscillatory power, both at these frequencies and at lower frequencies too, lies in a mesh pattern with cell scale 2 - 3 Mm, clearly larger than normal granulation, and with correlation times on the order of hours. The mesh pattern lies in the dark lanes between stable cells found in time-integrated G-band intensity images. It also underlies part of the bright pattern in time-integrated H-line emission. This discovery may reflect dynamical constraints on the sizes of rising granular convection cells together with the turbulence created in strong intercellular downflows.