SOFIA is in New Zealand for the third time – it visited the country in 2013 and 2015 as well. On 6 June 2016, the joint NASA and German Aerospace Center (Deutsches Zentrum für Luft- und Raumfahrt; DLR) flying observatory landed at Christchurch Internationl Airport at 01:37 CEST (11:37 local time). The Stratospheric Observatory for Infrared Astronomy (SOFIA) will embark on the first scientific flight of this year's campaign in the southern hemisphere on 9 June. Equipped with the German-built remote infrared spectrometers GREAT (German Receiver for Astronomy at Terahertz Frequencies) and FIFI-LS (Field-Imaging Far-Infrared Line Spectrometer), as well as with the US FORCAST (Faint Object InfraRedCAmera for the SOFIA Telescope) SOFIA will conduct a total of 25 observation flights until 20 July 2016.
With these instruments, it is possible to observe molecular and dust clouds in star forming regions. The scientists will be looking in particular at our neighbouring dwarf galaxies, the Large and Small Magellanic Cloud – visible only in the southern sky – as well as at the motion of matter in the centre of our Milky Way, to compare the star forming regions in these different types of galaxies.
"During this year's research programme, for the first time three observation instruments will be used. For the scientists, this is a major benefit, as such star-forming regions can be observed in various stages of their development," explains Alois Himmes, SOFIA Project Manager at the DLR Space Administration. As an example, the spectral 'fingerprints' of atoms and molecules can be measured to determine the gas densities, temperatures and velocities of the clouds. "The full dynamics of star formation can thus be examined in detail – from huge but less dense molecular clouds, to small but compact clouds and the so-called protoplanetary discs, in the centre of which a new star has already started to shine," adds Himmes.
SOFIA left its home base in Palmdale, California on 4 June 2016 and landed in Christchurch, New Zealand after a refuelling stop in Hawaii. During this transfer flight, FIFI-LS and FORCAST were stowed in special transport racks in the cargo bay of the Boeing 747SP. GREAT was already attached to the instrument flange of the 2.7-metre diameter telescope installed on the Jumbo jet. "GREAT was used in the recent research flights from Palmdale and will also be used for the first eight flights in New Zealand," explains Himmes.
More than 100 staff members – including scientists, pilots, engineers, maintenance and security staff – will be in Christchurch until the end of July. SOFIA takes advantage of the long winter nights in New Zealand because, during this time, the water vapour concentration in Earth's atmosphere is much lower than in the northern hemisphere summer. Even the smallest amount of water vapour in the air absorbs the infrared radiation, and it can no longer be measured by the spectrometers.
Exploring vast molecular clouds with GREAT
For the first time, an upgraded version of GREAT will also be flying in New Zealand – upGREAT. Instead of one detector, like in GREAT, upGREAT operates 14 detectors simultaneously. These are divided into two arrays and can therefore map a molecular cloud significantly faster. "With upGREAT, the performance and observing efficiency of our instruments is increased approximately 10 times, and new unexplored frequency ranges become accessible," explains Rolf Güsten, head of the GREAT instrument at the Max Planck Institute for Radio Astronomy in Bonn. "This year, the investigations will focus on the mapping of atomic oxygen in the Magellanic Clouds and in the galactic centre to study the chemistry of protoplanetary disks and planetary nebula, as well as the hunt for molecules thus far not detected in space."
FIFI-LS acquires data on star formation
FIFI-LS will be exploring the southern hemisphere for the first time. This instrument observes with substantially more wavelengths than GREAT, and can perform faster large-scale mapping of extensive molecular clouds. This time, FIFI-LS will be used to study the elements oxygen, nitrogen and carbon in star forming regions and the interstellar medium – the space between the stars both in our Milky Way and in other more distant galaxies. "This allows us to generate a detailed inventory of the material in the vicinity of the galactic centre," explains Alfred Krabbe, head of the FIFI-LS instrument and the German SOFIA Institute (DSI) at the University of Stuttgart. "We will also investigate the large star-forming region in the Large Magellanic Cloud. This can only be done from New Zealand."
FORCAST closes the campaign
During its nine flights, FORCAST will measure at shorter wavelengths than FIFI-LS and observe in particular dust discs around newly formed stars, but also the dust that has been thrown back into the Universe by old stars and supernovae. On 25 July, SOFIA will fly back to Palmdale again. Following a period of maintenance of the aircraft and the telescope, another 40 scientific flights will be carried out from California from mid-August until the end of 2016.