The Aurora Borealis or Northern Lights. The green glow is caused by the radiation of oxygen atoms in the upper atmosphere.
The collimated jet from HH 111. The driving source is in the vicinity of the bright knot of emission towards the right of the image. Note how focussed the jet is and that it terminates in a bow shock.
The quasi- spherical continuous solar wind. |
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Jets From Young Stars Our universe is an extremely energetic and dynamic place and astronomers are now privy to many of the violent processes and interactions taking place. One thing that has become clear is that astronomical winds play a pivotal role in much of this activity. For example take stellar winds. Starting in our own neighbourhood, our star, the Sun has a continuous wind which often manifests itself in the form of huge solar flares. The effect of the outflowing of matter from the Sun is clearly seen in the form of spectacular auroras on Earth, which have been studied now for many hundreds of years. Winds persist for the lifetimes of all stars from the smallest (not much smaller than our sun) to massive blue and red Giants. Astronomical jets, which are the particular focus of the JETSET research training network, are one form of wind. In this particular case, all the energy in the wind is focussed into a narrow powerful stream of gas (a process we term collimation), as it flows away from its source at hyper-sonic speeds. To the left the solar wind is compared to a jet from a young star to illustrate this point. Winds in the form of fast jets are an integral part of the formation and evolution of objects ranging from young stars “protostars” to active galactic nuclei (AGNs). It is the primary aim of JETSET to provide insights into all aspects of astronomical jets (see work package descriptions). JETSET will approach this task by concentrating its efforts in three specific areas: obtaining better higher resolution observations of the jet launch region, the development of more innovative analytical and computational models and by pioneering a lab based experimental approach to the study of the jets. The jets themselves are not only highly collimated but can stretch for many light years moving at hundreds of kilometers per second. Although we do not fully understand how they are launched, it is clear that they are an integral part of the star formation process. Once a cloud collapses under its own weight to form a star, the protostar launches powerful bipolar jets which plough through and strongly interact with its environment. JETSET will focus exclusively on jets from young stars.
Star Formation and Stellar Nurseries |
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