Research Fellows Directory
Dr Vasilis Archontis
University of St Andrews
The activity on the Sun is mainly driven by magnetic fields of various scales, which are originally formed in the solar interior but eventually they emerge into the outer atmosphere (solar corona). On small-scales, observations have revealed that the solar surface is carpeted with thousands of small-scale magnetic sources (similar to north and south poles of a bar magnet) joined by loops of magnetic field lines. We study how these loops form and interact with each other. This interaction may release enough energy to heat the solar corona. Coronal heating (corona is 100 times hotter than the solar surface!) is a long standing mystery in astrophysics.
On large-scales, magnetic fields (~ 30000 Km) burst from the solar interior to form Active Regions (ARs) at the solar surface that appear bright in X-rays and consist of magnetic fields in arches and loops. ARs are the building blocks of solar magnetic activity but the process of their formation is still unknown. To study this, we perform three-dimensional experiments of rising magnetic fields in a highly stratified atmosphere. We investigate how the emergence of magnetic flux leads to the formation of an AR and how these regions evolve during their lifetime. ARs are commonly associated with the release of a considerable amount of energy and flux (e.g. jets) and the onset of dramatic explosions known as Coronal Mass Ejections (CMEs). Small and large-scale jets may contribute (through the release of energy and flux) to the heating of the solar corona and the driving of the solar wind. CMEs may eject a vast amount of material, high energy gamma and X-rays toward Earth, impact satellites and disrupt signals from GPS satellites. Our aim is to find the properties of solar magnetic fields that emerge to form ARs and lead to the onset of hot/fast jets and/or the triggering of CMEs.
Interests and expertise (Subject groups)