The Officials' Dwellings

In the former astronomers' apartments, today researchers investigate stellar astrophysics and cosmic magnetic fields. They study physical processes in stars and the role of magnetic fields in various astronomical objects. Planets like the Earth usually have a magnetic field, as well as the Sun with its complex structure of magnetic fields. Galaxies like the Milky Way and presumably the entire cosmos are pervaded by magnetic fields. Up to now, there has been little research on the origin of these large-scale magnetic fields. The magnetic fields of the Sun generate sunspots; indirectly, they also cause the formation of aurorae in the Earth´s atmosphere. The Sun' s magnetic fields affect its outer layers, like the so-called corona. It is millions of degrees and without observational instruments is only visible during a solar eclipse.

In comparison to other stars, our Sun is not very active. In particular, young stars are much more active and have much stronger magnetic fields. If the Sun' s magnetic fields were like those of young stars, the conditions for life on Earth would be much worse; higher forms of life would probably exist only in the seas.

 

Fig. 1: Time series of x-ray images of the solar corona taken every six months from 1991 to 1995 by the satellite Yohkoh. The x-ray brightness of the Sun in the first image is 100 times greater than in the final image.

 

Fig.2:  The Hamburg telescope TIGRE is a 1.2m reflector for observing stellar activity of stars. It is located at the Observatory La Luz of the University Guanajuato in Mexico. TIGRE works robotically, with the programming and monitoring being performed from Bergedorf.

 

 

Galaxies and magnetic fields as computer models

The dynamics of stars or entire galaxies are very complex. Many physical processes act on various temporal and spatial scales. In these processes, magnetic fields play a significant role, although this has not been extensively explored. To get an overall picture, astrophysicists in Hamburg design theoretical models of magnetic field distribution. In some cases, the creation of a model demands months of computing time with the most modern and powerful supercomputers.

These models enable large-scale simulations of magnetic fields in galaxies to be performed, allowing researchers to investigate the distribution of physical quantities such as the temperature, density or magnetisation. On smaller scales, these models help understand the effect of cosmic magnetic fields on the structure of molecular clouds – the cradle of stars.

 

 Fig. 1: Simulation of the magnetic fields in the disc of a galaxy without spiral arms. The shading illustrates the density of matter in the galaxy: the brighter a region, the more matter it contains. The blue lines and arrows show the direction of the magnetic fields.

 Fig. 2: Lateral view of the same simulation. The wide extension of the magnetic fields reaching out into the intergalactic space is remarkable.