Hinode and IRIS observations of the magnetohydrodynamic waves propagating from the photosphere to the chromosphere in a sunspot

Abstract

Magnetohydrodynamic (MHD) waves have been considered as energy sources for heating the solar chromosphere and the corona. Although MHD waves have been observed in the solar atmosphere, there are a lack of quantitative estimates on the energy transfer and dissipation in the atmosphere. We performed simultaneous Hinode and IRIS observations of a sunspot umbra to derive the upward energy fluxes at two different atmospheric layers (photosphere and lower transition region) and estimate the energy dissipation. The observations revealed some properties of the observed periodic oscillations in physical quantities, such as their phase relations, temporal behaviors, and power spectra, making a conclusion that standing slow-mode waves are dominant at the photosphere with their high-frequency leakage, which is observed as upward waves at the chromosphere and the lower transition region. Our estimates of upward energy fluxes are $2.0\times 10^7$ erg cm${}^{-2}$ s${}^{-1}$ at the photospheric level and $8.3\times 10^4$ erg cm${}^{-2}$ s${}^{-1}$ at the lower transition region level. The difference between the energy fluxes is larger than the energy required to maintain the chromosphere in the sunspot umbrae, suggesting that the observed waves can make a crucial contribution to the heating of the chromosphere in the sunspot umbrae. In contrast, the upward energy flux derived at the lower transition region level is smaller than the energy flux required for heating the corona, implying that we may need another heating mechanism. We should, however, note a possibility that the energy dissipated at the chromosphere might be overestimated because of the opacity effect.

36 pages, 11 figures, accepted for publication in ApJ

References in corpus (2)

• The Solar Optical Telescope for the Hinode Mission: An Overview
• Synthetic observations of wave propagation in a sunspot umbra

Cited by in corpus (6)

• The Frequency-dependent Damping of Slow Magnetoacoustic Waves in a Sunspot Umbral Atmosphere
• Numerical determination of the cutoff frequency in solar models
• Observed local dispersion relations for magneto-acoustic-gravity waves in the Sun's atmosphere: Mapping the acoustic cut-off frequency
• IRIS observations of chromospheric heating by acoustic waves in solar quiet and active regions
• Three-minute Sunspot Oscillations Driven by Magnetic Reconnection in a Light Bridge
• Oscillations observed in Umbra, Plage, Quiet-Sun and the Polarity Inversion Line of Active Region 11158 using HMI/SDO Data