First insights from the distant cold
For more than a year now, the Apex telescope in Chile has been erasing knowledge gaps from the cosmic map - since then it has been providing insights from the neglected submillimetre range and allowing conclusions to be drawn about how the first stars and galaxies formed.
A good two dozen fresh releases demonstrate the value of the Atacama Pathfinder Experiment (APEX) that went live a year ago. The 12-meter telescope for wavelengths in the submillimeter range - it stands on the 5100-meter high Chajnantor plateau of the Atacama Desert in Chile, probably the driest place on earth - seems in fact sensitive and accurate enough to fulfill its ambitious goals tasks and questions The operators of the Max Planck Institute for Radio Astronomy, the European Southern Observatory (ESO) and the Swedish Onsala Space Observatory are happy to answer the question of star formation and astrochemistry.
APEX, designed for the wavelength range from 0.2 to 1.5 millimeters, offers access to completely new areas in astronomical observation from its very unusual location: With millimeter and submillimeter astronomy, the formation of the very first galaxies is to be observed in the universe, the formation processes of stars and planets and the chemistry and physics of molecular clouds – i.e. the dense gas and dust regions in which new stars are formed.
New Molecules and Wavelength Limits
One of the first successes of APEX is the discovery of a previously unknown, charged interstellar molecule: APEX and the 30-meter telescope from IRAM were able to observe the ion CF+, which consists of carbon and fluorine. So far, only one type of fluorine-containing molecule, HF, has been detected in space. The radio astronomers found the newly discovered ion, which is created by a reaction between carbon and the HF molecule, in the vicinity of the Orion Nebula, one of the closest and most active star birthplaces in our Milky Way. This discovery aids astronomers' understanding of interstellar fluorine chemistry and suggests that the HF molecule is widespread in interstellar molecular clouds.
Another first, again in the Orion region, was the discovery of 0.2 millimeter radiation from carbon monoxide (CO). Such short wavelengths are a particular challenge for research, because the water vapor in the earth's atmosphere absorbs them even more than the other wavelengths in the submillimeter range, and because they are at the very edge of the range for which APEX was designed. The detection of CO at these very shortest wavelengths accessible from Earth in one of the submillimeter "windows" is a testament to the excellence of the APEX telescope.
In addition, the scientists detected the emission of a molecule composed of hydrogen and deuterium (H2D+) in several cold dark clouds in the southern sky. This molecule is of particular interstellar importance because it still occurs in extremely cold gases (a few degrees above absolute zero), i.e. at temperatures below which almost all other types of molecules on the surface of interstellar dust grains have frozen out and can therefore hardly be observed.
Deep Looks at the Pillars of Creation
But these are not the only new findings: In addition, for example, there is the first observation of atomic carbon in the so-called "Pillars of Creation" in the Eagle Nebula (aka Messier 16) as well as investigations of the formation regions of massive stars and embedded hot cores in the submillimetre range. It was also possible to determine the mass and energy balance of high-velocity molecular outflows emanating from young stellar objects in these regions. Systematic measurements showed the particular variety of molecule types that can be observed in the submillimetre band.
Submillimetre observations of molecular regions in the dwarf galaxy NGC 6822 and the starburst galaxy NGC 253 show that APEX can also be used to study extragalactic sources.
Besides these astronomical studies, the operators are now also publishing a number of scientific papers on the technical aspects of APEX, such as the telescope itself, its software, receivers and spectrometers. The latter were developed at the Max Planck Institute for Radio Astronomy in Bonn and at Chalmers University in Sweden, while the guest receiver for 0.2 millimeter radiation was built at the University of Cologne.
APEX is also intended to pave the way for the much larger ALMA project (Atacama Large Millimeter Array): It uses a modified prototype of the ALMA antennas and stands on the site of the future ALMA observatory. ALMA is said to be made up of a vast network of dozens of 12-meter antennas spaced up to 14 kilometers apart. ALMA is expected to be phased in towards the end of this decade. This network of telescopes will make it possible to use the radio astronomical technique of aperture synthesis in submillimetre astronomy, enabling accurate imaging of objects at sub-arcsecond scales and thus complementing the optical observations of ESO's VLT/VLTI Observatory. © Max Planck Society
The Max Planck Society (MPG) is a basic research institution funded primarily by the federal and state governments. It operates around eighty Max Planck Institutes.
