In this Licentiate thesis I review the properties of the solar atmosphere and the diagnostic value ofdifferent spectral lines in the visible and ultraviolet (UV) along with the millimeter (mm) continua in theelectromagnetic spectrum of the Sun.While the solar atmosphere has been routinely observed in high-resolution from ground-based opti-cal telescopes such as the Swedish Solar Telescope (SST), and more recently in the UV from space tele-scopes such as the Interface Region Imaging Spectrograph (IRIS), radio observations lag behind despitetheir 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 differentfrequencies at potentially milliarcsecond scales if the full array is able to operate with the longest base-lines. This new spectral window onto the Sun is expected to advance various fields of research suchas 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 themm-intensities can be modelled by simply assuming local-thermodynamic equilibrium.In da Silva Santos et al. (2018) we find that coordinated observations from SST, IRIS and ALMA willpermit us to estimate with greater accuracy the full thermodynamical state of the plasma as a functionof optical depth based on experiments with a snapshot of a three-dimensional magnetohydrodynamicsimulation of the Sun’s atmosphere. Particularly, the mm-continuum improves the accuracy of inferredtemperatures in the chromosphere. Here we expand on the Why and How this can be done. The goal isto better constrain the temperature stratification in the solar atmosphere in order to understand chromo-spheric heating.
| Identifer | oai:union.ndltd.org:UPSALLA1/oai:DiVA.org:su-162711 |
| Date | January 2018 |
| Creators | da Silva Santos, João Manuel |
| Publisher | Stockholms universitet, Institutionen för astronomi, Stockholm |
| Source Sets | DiVA Archive at Upsalla University |
| Language | English |
| Detected Language | English |
| Type | Licentiate thesis, comprehensive summary, info:eu-repo/semantics/masterThesis, text |
| Format | application/pdf |
| Rights | info:eu-repo/semantics/openAccess |
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