Press Release 7/2011

Press Release 7/2011 - April 7, 2011

High Flying Astronomy with German Instrument

First Flight of SOFIA Airborne Observatory with GREAT Spectrometer.

SOFIA, the "Stratospheric Observatory for Infrared Astronomy", completed the first science flight on the morning of Wednesday, 6 April 2011, using the German Receiver for Astronomy at Terahertz Frequencies (GREAT) scientific instrument. The First results with GREAT include spectra of M17, an active star-forming region in our Milky Way, and the galaxy IC 342 at a distance of a few million light years. At altitudes up to 13 km the Earth's atmosphere enables the observation of far infrared radiation from space, giving access to a number of astronomically important spectroscopic lines. The GREAT instrument was developed by a team from the Max Planck Institute for Radio Astronomy (MPIfR) and the Universität zu Köln, led by Rolf Güsten, in collaboration with the Max Planck Institute for Solar System Research and the DLR Institute of Planetary Research.

On 6 April 2011, German scientists carried out their first astronomical observations on board the Stratospheric Observatory for Infrared Astronomy, SOFIA. A joint project between NASA and the German Aerospace Center (Deutsches Zentrum für Luft- und Raumfahrt; DLR), SOFIA is the world's only operational airborne observatory. SOFIA flies at altitudes higher than 10 kilometres and thus is able to perform observations that are not possible with ground based telescopes, which are hindered due to absorption by water vapour.


Figure 1: GREAT collected its first THz photons from the M17SW star forming cloud on April 06, 2011. Superposed on a near-infrared false-colour image measured by the Spitzer Space Telescope (NASA/JPL-Caltech/M. Povich, Univ. Wisc.), we display selected spectra of ionized carbon ([CII], white line) and warm carbon monoxide (CO, green line). The high spectral resolution of GREAT is mandatory to study the velocity structure across the cloud as unveiled by the different line profiles. The field studied on the sky is overlaid on the infra-red image, and the velocity integrated distribution of [CII] and CO is displayed in the inserts at the bottom.


When on 6 April 2011 at 06.40 local time (15.40 CEST) SOFIA touched ground again at its home base, the Dryden Aircraft Operations Facility (DAOF) in Palmdale, California, Rolf Güsten and his team had successfully concluded their first science flight with GREAT - the German Receiver for Astronomy at Terahertz Frequencies. The instrument had pointed, among others, at IC342, a prominent intermediate spiral galaxy in the constellation Camelopardalis, and at the Omega Nebula (M17), a site of actively forming massive stars 5000 light-years from Earth. For both sources, the radiation from ionized carbon at 1.9 THz and high-rotational transitions of warm carbon monoxide were measured, demonstrating the instrument`s ability to probe the interstellar medium in the environments of newly formed massive stars. Rolf Güsten (Principal Investigator of GREAT) rejoices at the success: "These very first spectra are the reward for investing several long years into cutting edge technology developments, and underline the scientific potential of airborne FIR spectroscopy. The large collecting area of GREAT's 2.7-m diameter telescope together with an enormous progress in Terahertz technology allows a 100 times faster data collection compared to earlier experiments - opening a new pathway for unique scientific experiments".

GREAT observed the strongest emission lines cooling the interstellar medium. The balance between heating and cooling processes regulates the temperature of the interstellar medium, thereby controlling the initial conditions for the formation of new stars. Co-Investigator Jürgen Stutzki from Cologne University explains: "The ionized carbon line, excited by the strong ultraviolet radiation from newly born stars, gives us unique insight into the physical processes and chemical conditions in the stellar nurseries. SOFIA will help to obtain a significant insight into how young stars form and change the clouds they were born in".

"This first scientific flight of GREAT is the beginning of German-American scientific collaboration on SOFIA. We are confidently looking forward to the upcoming routine operations", said Alois Himmes, SOFIA Project Manager at DLR. After these first flights, SOFIA will be available to a broader community of astronomers. "During summer 2011 scientists out of the German astronomical community will observe with SOFIA the first time using either GREAT or the US Faint Object InfraRed-CAmera for the SOFIA Telescope, FORCAST", explains Prof. Alfred Krabbe, Head of DSI at the University of Stuttgart (Universität Stuttgart).


Figure 2: GREAT mounted at the telescope onboard SOFIA.
(Credits: NASA Photo/ Tom Tschida.)


GREAT, the German Receiver for Astronomy at Terahertz Frequencies, is a receiver for spectroscopic observations in the far infrared spectral regime between frequencies of 1.25 and 5 terahertz (60-240 microns), which are not accessible from the ground due to absorption by water vapour. GREAT is one of two first generation German SOFIA instruments, developed by the Max Planck Institute for Radio Astronomy (MPIfR) and the Universität zu Köln, 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 and the Deutche Forschungsgemeinschaft.

SOFIA, the "Stratospheric Observatory for Infrared Astronomy" is a joint project of the Deutsches Zentrum für Luft- und Raumfahrt e.V. (DLR; German Aerospace Centre, grant: 50OK0901) and the National Aeronautics and Space Administration (NASA). It is funded on behalf of DLR by the Federal Ministry of Economics and Technology based on legislation by the German Parliament, the state of Baden-Württemberg, and the Universität Stuttgart. Scientific operation for Germany is coordinated by the German SOFIA-Institute (DSI) of the Universität Stuttgart, in the US by the Universities Space Research Association (USRA).

M17SW, is a molecular cloud, containing about 10000 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 radiation from the cluster ionizes and heats the molecular gas, possibly compressing it into the state where more stars form from the compressed gas. The SOFIA observations permit to distinguish the effect of this radiative compression from the heating effect that would rather lead to an expansion. In this way, we can predict the future of the molecular cloud with regard to its star formation activity.

IC 342, is the nearest gas-rich spiral with active star formation in its nucleus. Within its central 30" two molecular arms end in a clumpy central ring of dense gas, surrounding a young star cluster. The young stars heat the ambient gas and dust and create a rich chemistry and intense emission from these regions, also called photon dominated regions (PDR). The strong emission from these PDRs allows an in depth study of the chemical and physical conditions in these distant massive star-forming regions.

Further Information

< SOFIA Science Center

< Deutsches SOFIA-Institut (DSI)

< Bilder und Videos zu SOFIA beim DSI



< Submillimeter Technology Group at MPIfR

> MPS SOFIA GREAT-CTS Projektseite

< I. Physikalisches Institut, Universität zu Köln

< Deutsches Zentrum für Luft- und Raumfahrt (DLR)

< DLR Webcast SOFIA (8'15")

< Movie (15min) über die GREAT-Installation an Bord von SOFIA (Henning Krause, s.o.); Video: DLR/GREAT


Dr. Rolf Güsten
GREAT Principal Investigator
Max-Planck-Institut für Radioastronomie, Bonn
Tel: +49 (0)228-525-383

Dr. Norbert Junkes
Press and Public Outreach
Max-Planck-Institut für Radioastronomie, Bonn
Tel: +49 (0)228-525-399

Dr. Susanne Herbst
Press and Public Outreach
I. Physikalisches Institut, Universität zu Köln
Tel: +49 (0)221-470-7028

Dr. Dörte Mehlert
Press and Public Outreach
Deutsches SOFIA-Institut
Tel: +49 (0)711-6856-9632

Henning Krause
Press and Public Outreach
Deutsches Zentrum für Luft- und Raumfahrt e.V.
Tel: +49 (0) 2203-601-2502

Dr. Birgit Krummheuer
Press and Public Relations
Max Planck Institute for Solar System Research
Max-Planck-Straße 2
37191 Katlenburg-Lindau
Tel.: 05556 979 462
Fax: 05556 979 240
Mobil: 0173 3958625

© 2009, Max Planck Institute for
Solar System Research, Lindau