High flying astronomy with German instrument

Infrared Spectrometer on board the SOFIA observatory successfully completes maiden flight

As the Jumbo touched down on the runway of the Dryden Aircraft Operations Facility in Palmdale/California at 6.40 am local time it heralded in a new era for observational astronomy: it was April 6, 2011, and the jet which had been converted into the SOFIA infrared observatory had just completed its first research flight with GREAT, the spectrometer developed by a team which included the Max Planck Institute for Radio Astronomy. The observation programme included the M 17 molecular cloud, a region of our galaxy with increased star formation, and also galaxy IC 342 only a few million light years away.

Glossary

GREAT
the German Receiver for Astronomy at Terahertz Frequencies, is a receiver for spectroscopic observations in the far-infrared region of the electromagnetic spectrum between frequencies of 1.25 and 5 terahertz (60-240 microns wavelength), which are not accessible from the ground because they are absorbed by water vapour in the atmosphere. GREAT was developed by the Max Planck Institute for Radio Astronomy (MPIfR) and the University of Cologne, in collaboration with the Max Planck Institute for Solar System Research and the DLR Institute of Planetary Research. Rolf Güsten (MPIfR) is the project manager for GREAT. The development of the instrument was financed by the participating institutes, the Max Planck Society, the German Research Foundation and the German Aerospace Center (DLR).

SOFIA
The Stratospheric Observatory for Infrared Astronomy is a joint project between the German Aerospace Center (DLR) and the National Aeronautics and Space Administration (NASA). It is funded on behalf of the DLR by the Federal Ministry of Economics and Technology on the basis of legislation by the German Parliament, and also by the State of Baden-Württemberg, and the University of Stuttgart. The operation of the scientific programme is coordinated in Germany by the German SOFIA Institute (DSI) at the University of Stuttgart; in the US the coordination is undertaken by the Universities Space Research Association (USRA).

M 17
An interstellar molecular cloud containing around 10,000 solar masses of gas that is illuminated by a cluster of young stars with a total luminosity of more than one million solar luminosities. The ultraviolet radiation from the cluster ionises and heats the molecular gas, possibly compressing it into a state which gives rise to more stars. The SOFIA observations make it possible to measure the effect of this compression and compare it to the heating effect of the gas that leads to an expansion. This enables us to investigate the star-forming process.

IC 342
The nearest gas-rich spiral galaxy with active star formation in its nucleus. Within its central 30 arc seconds two spiral arms with molecular gas end in a clumpy central ring of dense gas, which in turn surrounds a young star cluster. Its massive young stars heat the ambient gas and dust and create a rich chemistry and intense emission from this region, which specialists call a photon dominated region (PDR). The intense emission from these PDRs allows the in-depth study of the chemical and physical conditions for the formation of massive stars - not only in our Milky Way, but also in neighbouring galaxies.