Physics projects for Y3 and Y4 students

Project description

Measuring magnetic fields in sunspots

(supervisor: David Kuridze)

Nature of project: data analysis, theory

Available to students on full-time physics degree schemes or joint students.

Project description and methodology

Sunspots are manifestation of strong magnetic field coming up from within the Sun’s interior and appear as dark regions on the surface. Sunspots, often the size of the earth or larger, are dark because they are cooler than their surroundings. They appear alone or in small groups called magnetic active regions and have lifetimes between several hours and weeks. The aim of this project is to measure the sunspot magnetic field using polarized states of light described by the Stokes profiles (I, Q, U, V ) in the magnetically sensitive spectral lines. The student will use high-resolution spectropolarimetric data from the Swedish 1-m Solar Telescope. The data will be used for calculation of a spatially averaged magnetic field strength of the sunspot using different methods (inversion algorithm, weak-field approximation).

A successful project will develop beyond the above in one/some of the following directions:
The main way to develop this project further is to measure magnetic field for spatially resolved sunspot features, such as umbra, penumbra, Lightbridge, and investigate time evolution of the sunspot field.

When considering where to take your project, please bear in mind the time available. It is preferable to do fewer things well than to try many and not get conclusive results on any of them. However, sometimes it is useful to have a couple of strands of investigation in parallel to work on in case delays occur.

Additional scope or challenge if taken as a Year-4 project: For a 4th year project, student can use multi wavelength data to investigate sunspot field at different height in the solar atmosphere.

Please speak to David Kuridze if you consider doing this project.

Initial literature for students:

  1. The Sun as a guide to Stellar Physcis, Editors: Oddbjørn Engvold, Jean-Claude Vial, Andrew Skumanich (book, chapter 5.3), ELSEVIER, 2019
  2. Kuridze, D., Mathioudakis, M., Morgan, H., et al. 2019, The Astrophysical Journal, 874, 126
  3. Wiegelmann, T., Thalmann, J., Solanki, S., 2014, The Astronomy and Astrophysics Review, Volume 22, 78, 106

Novelty, degree of difficulty and amount of assistance required

Fully processed data will be provided. Student should be able to use IDL. Inversion software is written and publicly available. Assistance to set up the software and learn how to use it will be provided.

Project milestones and deliverables (including timescale)

milestoneto be completed by
Review of mathematical formalism (Stokes formalism) of polarization of lightend of October
Learning how to open/load the SST spectropolarimetric data in IDL and understanding its structure Christmas
Running inversion code to measure magnetic fieldend of February
Analyses of inversion resultsEaster