Main Objective: Investigation the role of waves in chromospheric and coronal heating in different magnetic field structures.
Scientific Justification: The heating of the solar corona has remained an unsolved problem in solar physics. Propagating magnetoacoustic waves have been thought to be an important source of energy needed to balance radiation losses in the solar chromosphere and corona. Although many observational studies have examined the oscillations in the solar atmosphere as a candidate for the heating mechanism, it is still not fully understood. For example, there are a variety of magnetic field structures on the solar surface such as sunspots, plages, and quiet network, but there are few systematic studies on the relation between wave propagation and the magnetic field structures seen from different view angles.
We will observe (a) network in quiet regions and (b) sunspots and plages in active regions in multiple spectral lines to track the propagating waves from the photosphere to the corona, and also observe these structures from different angles. To this end, we will conduct the spectroscopic observations of plasma in each structure using DST (Domeless Solar Telescope at Hida Obs. of Kyoto Univ., Japan) for photosphere and chromosphere, IRIS for upper chromosphere and transition region, and EIS/Hinode for corona.
From the fluctuations in line-of-sight velocity and intensity, we will investigate the variation of the amplitude and the phase relations among the different heights and physical quantities as a function of period. Then, we will identify the mode of MHD waves and examine the energy flux in the different magnetic field structures.
In our preliminary study, using H-alpha full disk Dopplergrams, we found that the chromosphere has significant power in the period down to 100 seconds or shorter in line-of-site velocity. We also found characteristic center-to-limb variations in the power of Doppler velocity in 3-minute, 5-minute, and around 20-minute periods associated with different magnetic field structures. So we want to request a time cadence shorter than 20 seconds and also want to observe each target near the disk center and far from the disk center. |
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