Fig. I.5: Design diagram of the Large Binocular Telescope. It will carry two primary mirrors with a diameter of 8.4 metres, whose beams can be made to interfere. The fully-grown elephant serves to give an idea of size.
Some Important Questions  
case, the equatorial dust disk mentioned above forms the plane of symmetry to the flows and the bright gas clouds. The MPIA’s astronomers are seeking answers to some important questions such as: how are the particles accelerated? How long does the bipolar phase last? Does every newly born star generate flows of this sort, and what role does this phenomenon play in the development of young stars?
The later stages of stars are also being investigated at the MPIA. Stars which are substantially more massive than the sun explode as Type II supernovae at the end of their lives. What happens in the last ten thousand years before the explosion? We are now familiar with a class of stars which are probably in this pre-supernova stage: the Luminous Blue Variables. Evidently they too are already casting off parts of their outer shell as they create a gas cloud around themselves. One of these nebulae has been examined at the MPIA – it contained a bipolar structure whose cause has still not been clarified.

Extragalactic Research

It is a cosmologist’s dream to be able to look back into the era of the universe when the first galaxies were being formed. However, the protogalaxies are so remote, and
the light from them is consequently so faint, that it has so far been impossible to discover them. In order to attain this goal, astronomers must use sensitive detectors working at the limits of the most powerful telescopes, and they also need to develop ingenious search strategies. Since the mid-1990’s, the CADIS (Calar Alto Deep Imaging Survey) observation programme has been running on the 2.2- and 3.5-metre telescope at Calar Alto, with the aim of searching for the first galaxies in the universe (Chapter II.2). This programme is intended to run for at least five years and it is currently one of the MPIA’s key projects.
The question as to the evolution of galaxies is also closely linked to the question of the nature of quasars. These are compact regions in the centre of certain galaxies. From a region which is probably not very much larger than our planetary system, they are able to radiate several tens of thousands of times more energy than all the stars in the surrounding galaxy taken together. According to the theory which is current today, a massive Black Hole is located at the centre of a quasar; this sucks in the surrounding matter, and the observed radiation is released. The investigation of quasars and of the galaxies at whose centres they are located (the mother galaxies) has been one of the MPIA’s fields of work for many years now.
Another focus of extragalactic research at the MPIA is the investigation of jets from galaxies: this phenomenon shows remarkable similarities to the bipolar flows from stars, but it is on a substantially larger scale. In this case, one or two collimated jets of particles emanate from a central source – a quasar or a radio galaxy – to end in large clouds (or lobes, as they are known), where they dissipate. In the interior of the jets, electrically charged particles (electrons and possibly positrons) are moving in strong magnetic fields at almost the speed of light. Since the 1980’s, the MPIA has been making major contributions to the issue of how the particles are accelerated in the jet, although this issue has still not been finally clarified. (Chapter IV.2).
Researchers at the MPIA also deal with normal spiral galaxies, of the same type as our Milky Way system. The arms of the spiral play a decisive part in the birth of stars, and therefore in the development of galaxies. However, many fundamental aspects of this phenomenon have still not been understood. How do the spiral arms come into being, and for how long do they remain stable? In addition to this, some spiral galaxies, probably including our own Milky Way, possess a bar-shaped structure which runs through the central region, with the spiral arms starting at its ends. Under what conditions are the bars created, and why do they not form in all spiral galaxies? At the MPIA, these questions are investigated with the help of computer models which are used to interpret observations (Chapter IV.2).
Although the spiral structure is the most striking feature of the spiral galaxies, it has become increasingly

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