SOFIA, the "Stratospheric Observatory for Infrared Astronomy", completed its first series of science flights, using the German Receiver for Astronomy at Terahertz Frequencies (GREAT). The scientific results are now being published in a special issue of the European journal “Astronomy & Astrophysics” (Volume 542, May 10) along with reports on GREAT’s advanced technologies. They include first detections of new interstellar molecules and important spectral lines in space, and address different stages of the star formation process. The “Deutsches SOFIA Institut” (DSI) of the University of Stuttgart coordinates SOFIA’s science mission and operation on behalf of the German partners.
The first series of astronomical observations with GREAT on board of SOFIA were successfully completed in November 2011. Now, six months later, the scientific results have been published in a special issue of the prestigious European journal “Astronomy & Astrophysics”. In total, 22 articles by an international group of scientists report on the first astronomical results as well as the technologies employed in the GREAT instrument on board SOFIA.
As a joint project between NASA and the German Aerospace Center (Deutsches Zentrum für Luft- und Raumfahrt, DLR), SOFIA operates a 2.7-m telescope in a modified Boeing 747SP aircraft and is the world's largest ever airborne infrared observatory. SOFIA flies at altitudes as high as 13700 meters to provide access to astronomical signals at far-infrared wavelengths that would otherwise be blocked due to absorption by water vapour in the atmosphere. The SOFIA observatory and the GREAT instrument open the far-infrared skies for high-resolution spectroscopy, and GREAT pushes its technology to higher frequencies and sensitivities than ever reached before.
Many of the contributed papers study the star formation process in its earliest phases, first when the protostellar molecular cloud is contracting and condensing, and then when the embryonic star is vigorously interacting with its surrounding parental molecular cloud –tearing it apart and ionizing it. The high spectral resolution capabilities of GREAT enabled scientists to resolve the velocity field of gas in the parental molecular clouds traced by the important cooling line radiation of ionized carbon in several star forming regions.
GREAT detected the velocity signature of infalling gas motion (“collapse”) in the envelopes of three protostars, directly probing the dynamics of a forming star. Two interstellar molecular species were detected for the first time ever: OD, an isotopic substitute of hydroxyl (OH) with the hydrogen atom replaced by the heavier deuterium, and the mercapto radical SH. Observations of the ground-state transition of OH at a frequency of 2.5 Terahertz (120 microns wavelength) explored new astrochemical territories while pushing the technological frontier.
The remnant envelope of an evolved star, ionized by its hot stellar core, was also investigated
as was the violent shock interaction of a supernova remnant and the surrounding interstellar
medium. Furthermore, the circumnuclear accretion disk, ultimately feeding the black hole in the
centre of the Milky Way galaxy was studied, as well as star formation in the circumnuclear region
of the nearby galaxy IC342.
“The rich harvest of scientific results from this first observing campaign with SOFIA and the
GREAT instrument gives a first glimpse of the tremendous scientific potential of this observatory
and promises unique astronomical observations for years to come, particularly in the topical
research areas of star formation and astrochemistry” states the Deputy Director of the SOFIA
Science Mission, Hans Zinnecker, from DSI. In parallel with Rolf Güsten from the
Max-Planck-Institut für Radioastronomie, the Principal Investigator of the GREAT project, Zinnecker
organized the selection process and ultimately selected some of the most exciting observing
proposals from the German astronomical community.
“The high resolving power of the GREAT spectrometer is designed for studies of interstellar gas and the stellar life cycle, from a protostar’s early embryonic phase when still embedded in its parental cloud to an evolved star’s death when the stellar envelope is ejected back into space”, says Güsten. “This stunning collection of first scientific results is reward for the many years of development work, and underlines the huge scientific potential of airborne far-infrared spectroscopy.”
Note that results and papers based on early science observations with the FORCAST receiver (mid-infrared camera) onboard SOFIA have been published in a special issue of the U.S. journal "Astrophysical Journal Letters" that was covered in a separate press release.
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 in the atmosphere. GREAT is a first generation German SOFIA instrument, developed by the
Max-Planck Institute for Radio Astronomy (MPIfR) and the KOSMA at the Universität zu Köln, in
collaboration with the Max-Planck Institute for Solar System Research and the DLR Institute for
Planetary Research. Rolf Güsten (MPIfR) is the Principal Investigator for GREAT. The development of
the instrument was financed by the participating institutes, the Max-Planck Society (MPG), and the
Deutsche Forschungsgemeinschaft (DFG).
SOFIA, the "Stratospheric Observatory for Infrared Astronomy" is a joint project of the
National Aeronautics and Space Administration (NASA) and the Deutsches Zentrum für Luft- und
Raumfahrt e.V. (DLR; German Aerospace Centre, grant: 50OK0901). 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 University of Stuttgart. Scientific operation for Germany is
coordinated by the German SOFIA-Institute (DSI) of the University of Stuttgart, in the US by the
Universities Space Research Association (USRA).
Original Papers:
http://www.aanda.org/index.php?option=com_toc&url=/articles/aa/abs/2012/06/contents/contents.html
http://www.mpifr.de/div/submmtech/heterodyne/great/GREAT_science.html
Parallel Press Releases:
A & A press release
http://www.aanda.org/index.php?option=com_content&task=view&id=823&Itemid=277
MPI fuer Radioastronomie
www.mpifr-bonn.mpg.de/public/pr/pr-great-may2012-en.html
DLR
http://www.dlr.de/dlr/en/desktopdefault.aspx/tabid-10081/151_read-3535/
Universität zu Köln
http://www.portal.uni-koeln.de/nachricht+M50a30d44785.html
NASA's SOFIA featured in the Astrophysical Journal Special Edition, http://www.nasa.gov/mission_pages/SOFIA/12-122HQ.html
Further Information:
Deutsches SOFIA-Institut (DSI)
Max-Planck-Institut für Radioastronomie (MPIfR).
GREAT and Submillimeter Technology Group at MPIfR.
KOSMA, I. Physikalisches Institut der Universität zu Köln.
Deutsches Zentrum für Luft- und Raumfahrt (DLR).
NASA/SOFIA and SOFIA Science Center.
Contact Information:
Deutsches SOFIA-Institut:
Hans Zinnecker
Deputy Director - SOFIA Sciences Mission
Fon:
E-mail:
hzinnecker@sofia.usra.edu
Dörte Mehlert,
Press and Public Outreach,
Fon: +49(0)711-6856-9632
E-mail:
mehlert@dsi.uni-stuttgart.de
Max-Planck-Institut für Radioastronomie
Rolf Güsten,
GREAT Principal Investigator,
Max-Planck-Institut für Radioastronomie, Bonn.
Fon: +49(0)228-525-383
E-mail:
rguesten@mpifr-bonn.mpg.de
Norbert Junkes,
Press and Public Outreach,
Fon: +49(0)228-525-399
E-mail:
njunkes@ mpifr-bonn.mpg.de
I. Physikalisches Institut, Universität zu Köln:
Susanne Herbst,
Scientific Coordinator,
Fon: +49(0)221-470-7028
E-mail:
herbst@ph1.uni-koeln.de
Deutsches Zentrum für Luft- und Raumfahrt e.V.:
Henning Krause,
Press and Public Outreach,
Fon: +49(0)2203-601-2502
E-mail:
henning.krause@dlr.de
Max-Planck-Institut für Sonnensystemforschung:
Birgit Krummheuer,
Press and Public Outreach,
Fon: +49(0)5556-979-462 (mobile: 0173 3958625)
E-mail:
krummheuer@mps.mpg.de
