Join the disputation
The PhD defence and trial lecture will be 100% in-person. The room opens for participation just before the disputation starts, and closes for new participants approximately 15 minutes after the defence has begun.
Join the trial lecture - 5th of December at 10:15 (Aud. 209, Svein Rosselands Hus)
“Zeeman Doppler Imaging and Stellar Magnetic Fields”
Conferral summary
This thesis explores the Sun as a benchmark for studying sun-like stars, employing spectral lines like Ca II and Hα to examine their atmospheric activity along with the millimetre data from Atacama Large Millimetre/submillimetre (ALMA), which offers a fresh perspective on stellar activity and thermal structure. Comparing synthetic spectra with millimetre maps and combining long-term solar observations from ALMA with various diagnostic tools reveals thermal structure and long-term variations in the solar activity, which emphasises ALMA's pivotal role in advancing our understanding of solar and stellar activity.
Shining Light on Solar-Stellar Activity with ALMA
The Sun is a stellar role model: it can be observed and studied closely and is treated as a benchmark for the study of the structure of sun-like stars. Traditional astrophysics research has heavily relied on spectral lines like Ca II and Hα, to explore the activity in the atmospheres of solar-like stars. Activity is a range of phenomena occurring in the outer layers of a star which can be observed as variations of the intensity.
However, probing plasma temperatures in stellar atmospheres directly is no small feat. Enter Atacama Large Millimetre/submillimetre (ALMA) observations, offering a fresh view of stellar activity and thermal structure.
In this thesis, I compare synthetic Ca II and Hα spectra with millimetre maps to gain a deeper understanding of the chromospheric properties of sun-like stars.
In addition, long-term solar observations from ALMA are combined with a range of other diagnostics, including UV/optical data, microwave data, and activity indices. These observations not only provide the first glimpse of long-term solar activity variation using ALMA data but also reveal intriguing short-term fluctuations.
In essence, this PhD thesis undertakes a comparative journey through solar and stellar activity. The study hinges on the incredible observations made by ALMA in conjunction with a wide range of observed and synthetic solar and stellar data.
Contact information for the Institute of Theoretical Astrophysics