Astronomical Observatory

Astronomical Observatory

The Astronomical Observatory of the University of Ghent dates from 1904, and was at that time located in the ``Institut des Sciences'', now known as the ``Plateau-Rozier'' building, in the center of town. The principal objective of its observing activities have been, and still are, educational. In the 1970s the observatory moved into a new location (ED50 coordinates 0h14m50.12s E, 51deg01'25'' N) at the Krijgslaan 281 (S9). It became a part of the Department of Mathematical Physics and Astronomy in 1993.

The old observatory (oude sterrenwacht) in the ``Plateau-Rozier'' building has been renovated and now serves as a public observatory. Its operations are for a large part managed by a society of amateur astronomers called Vrienden van de oude Sterrenwacht van de RUG, vzw (VSRUG)

Research activities

Stellar dynamics, galactic and extragalactic astronomy
In this research area most of the staff members are active. Stars form conglomerates that are called stellar systems. These contain from several hundred thousand (globular clusters) to several thousands of millions stars (galaxies). The study of stellar systems is a very vigorous research area in astronomy. Currently it is still not known how exactly stellar systems were born. Astronomers all over the world are probing the deep universe to find the progenitors of the galaxies as we know them today, using the most powerful telescopes.

At the Astronomical Observatory, the inner dynamical structure of stellar systems is studied. The main goal is to understand how galaxies can be in equilibrium, and how they evolve in time. This is done mainly by studying their light, both photometrically and spectroscopically, and by producing models that fit the observations. From these models, the essential characteristics of galaxies can be inferred.

More specifically, topics under study include

Space Plasma Waves
Plasmas in space (outside the Earth) are characterized by the presence of magnetic fields and more than one species of ions, often generated in different conditions and streaming with respect to each other. Some of the typical and most studied examples are the interaction of the solar wind (the expanding outer corona of the Sun) with cometary environments, or of the heliosphere (defined as the realm where the solar wind plasma dominates) with the surrounding interstellar matter. Highly successful missions to comets P/Giacobini-Zinner, P/Halley and P/Grigg-Skjellerup have shown how assimilation of cometary ions into the solar wind occur through collective effects which generate low-frequency turbulence. Why low-frequency electromagnetic fluctuations dominate is not quite clear.

Theoretical descriptions of such plasma modes and instabilities involve at least two distinct ion populations, rendering the treatment more complicated. Wave theory traditionally starts from linear modes, but the quasilinear and nonlinear aspects determine the ultimate levels of low-frequency turbulence. Good agreement has been reached in this stimulating interplay between theoretical concepts and observational evidence. There are similar applications to certain types of solar flares, magnetospheric and auroral plasmas and dusty plasmas in the solar system. The framework can even be used to model nonlinear mode coupling in stellar pulsations.

In particular, the study of waves in dusty plasmas has become a subject in its own right. Dust occurs in many astrophysical circumstances, like interstellar and circumstellar media, planetary rings and cometary comae and tails. These dust grains are immersed in ambient plasmas and become electrically charged by various processes, after which they interact with electromagnetic fields. Intriguing phenomena observed in the 1980s by Voyager cameras and attributed to micron-sized charged dust are radial spokes in the B-ring and braids in the F-ring of Saturn, not explainable by classical mechanical pictures. As the dust grains can have very high negative charges and in proportion even higher masses than ordinary ions, characteristic frequencies are considerably smaller than corresponding electron or ion quantities, giving rise to new low-frequency eigenmodes. Further complications arise because the dust charges fluctuate, leading to new electrostatic and electromagnetic instabilities.

We are interested in general treatments for low-frequency modes in plasmas with different ion species, and have studied appropriate generalizations of canonical nonlinear evolution equations, applicable to space plasmas. The modelling of variable dust charges and its influence on plasma waves is a recent theoretical challenge, for which much remains to be done.

Observing activities

Scientific and teaching staff

Maarten Baes
Herwig Dejonghe
Sven De Rijcke
Emmanuel Van Hese
Bart Catry
Frank Verheest

Technical staff

Guy Wauters

Related Student activities

Werkgroep Sterrenkunde

Related sites

Additional information can be obtained at