Licentiate thesis: Constraints on the gas temperature in the solar atmosphere from multiwavelength inversions
Thursday 15 November 2018
to 12:00 at
João M. da Silva Santos (Institute for Solar Physics, Department of Astronomy, Stockholm University)
While the solar atmosphere has been routinely observed in high-resolution from ground-based optical telescopes such as the Swedish Solar Telescope (SST), and more recently in the UV from space telescopes such as the Interface Region Imaging Spectrograph (IRIS), radio observations lag behind despite
their great usefulness. This is likely to change thanks to the Atacama Large Millimeter Array (ALMA) that only started observing the Sun in 2016 with a few limitations, but the first results are promising.
ALMA observations probe the solar chromosphere at different heights by tuning into slightly different frequencies at potentially milliarcsecond scales if the full array is able to operate with the longest baselines. This new spectral window onto the Sun is expected to advance various fields of research such as wave propagation and oscillations in the chromosphere, thermal structure of filaments/prominences, triggering of flares and microflares, and more generally chromospheric and coronal heating, because the mm-intensities can be modeled by simply assuming local-thermodynamic equilibrium.
We find that coordinated observations from SST, IRIS and ALMA will
permit us to estimate with greater accuracy the full thermodynamical state of the plasma as a function of optical depth. Particularly, the mm-continuum improves the accuracy of inferred temperatures in the chromosphere. Here we expand on the Why and How this can be done. The goal is to better constrain the temperature stratification in the solar atmosphere in order to understand chromospheric heating.