Advisors

Wiegelmann, Thomas
Thomas Wiegelmann
Scientist
Phone: +49 551 384 979-155
Schunker, Hannah
Hannah Schunker
Phone: +49 551 384 979-440
+49 551 384 979-299
Links: Homepage

Links

1.
Hannah Schunker, D. C. Braun, A. C. Birch, R. B. Burston, and L. Gizon, "SDO/HMI survey of emerging active regions for helioseismology," Astronomy and Astrophysics 595, A107 (2016).
2.
Thomas Wiegelmann and Takashi Sakurai, "Solar Force-free Magnetic Fields," Living Rev. Sol. Phys. 9, 5 (2012).

How to apply

Open PhD Project

Evolution of the coronal magnetic field of emerging active regions

Studying the vector magnetic field of emerging active regions on the Sun

Solar active regions on the surface of the Sun are the source of dynamic phenomena in the upper atmosphere of the Sun like flares and coronal mass ejections. However, it is not known how these active regions are formed, or how their formation affects the dynamics in the upper atmosphere. Data for close to 180 emerging active regions have been identified and are included in the SDO/Helioseismic and Emerging Active Region survey (Schunker et al. 2016). An important component which has not yet been studied is the vector magnetic field at the surface. The three-dimensional structure of the solar corona above active regions can be reconstructed, using these surface magnetograms, by the assumption of a vanishing Lorentz-force, the so-called force-free assumption (Wiegelmann and Sakurai 2012).

An example of an extrapolation of the magnetic field using surface observations from the SDO/HEAR survey of AR11158. Zoom Image
An example of an extrapolation of the magnetic field using surface observations from the SDO/HEAR survey of AR11158.

This project concentrates on studying the evolution of the vector magnetic field of active regions and the extension into the atmosphere as they emerge. From this, statistical studies can be done to understand the common physical properties of the emergence process, as well as any significant deviations. Some examples of specific questions that will be answered are:

  1. What is the orientation of the magnetic field when active regions begin forming?
  2. At what stage of the surface evolution do loops form?
  3. How do the loops evolve (twist, height, flux, area, complexity... .)?
  4. How fast do the loops evolve (height/time, flux/time, current/time, (free) energy etc.)?
 
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