New observations have brought to light that stars can form through the dynamic interaction of gas within interstellar gas clouds. This process unfolds faster than previously assumed, research within the FEEDBACK programme on board the flying observatory SOFIA revealed.
Gas clouds in the Cygnus X Region, a region where stars form, are composed of a dense core of molecular hydrogen (H2) and an atomic shell. These ensembles of clouds interact with each other dynamically in order to quickly form new stars. That is the result of observations conducted by an international team led by scientists at the University of Cologne’s Institute of Astrophysics and at the University of Maryland. Until now, it was unclear how this process precisely unfolds. The Cygnus X region is a vast luminous cloud of gas and dust approximately 5,000 light years from Earth. Using observations of spectral lines of ionized carbon (CII), the scientists showed that the clouds have formed there over several million years, which is a fast process by astronomical standards. The results of the study ‘Ionized carbon as a tracer for the assembly of interstellar clouds’ will appear in the next issue of Nature Astronomy. The paper is already accessible online.
The observations were carried out in an international project led by Dr Nicola Schneider at the University of Cologne and Prof Alexander Tielens at the University of Maryland as part of the FEEDBACK programme on board the flying observatory SOFIA (Stratospheric Observatory for Infrared Astronomy). The new findings modify previous perceptions that this specific process of star formation is quasi-static and quite slow. The dynamic formation process now observed would also explain the formation of particularly massive stars.
By comparing the distribution of ionized carbon, molecular carbon monoxide and atomic hydrogen, the team found that the shells of interstellar gas clouds are made of hydrogen and collide with each other at speeds of up to twenty kilometres per second. “This high speed compresses the gas into denser molecular regions where new, mainly massive stars form. We needed the CII observations to detect this otherwise ‘dark’ gas,” said Dr Schneider. The observations show for the first time the faint CII radiation from the periphery of the clouds, which could not be observed before. Only SOFIA and its sensitive instruments were capable of detecting this radiation.
SOFIA was operated by NASA and the German Aerospace Center (DLR) until September 2022. The observatory consisted of a converted Boeing 747 with a built-in 2.7-metre telescope. It was coordinated by the German SOFIA Institute (DSI) and the Universities Space Research Association (USRA). SOFIA observed the sky from the stratosphere (above 13 kilometres) and covered the infrared region of the electromagnetic spectrum, just beyond what humans can see. The Boeing thus flew above most of the water vapour in the Earth’s atmosphere, which otherwise blocks out infrared light. This allowed the scientists to observe a wavelength range that is not accessible from Earth. For the current results, the team used the upGREAT receiver installed on SOFIA in 2015 by the Max Planck Institute for Radio Astronomy in Bonn and the University of Cologne.
Even though SOFIA is no longer in operation, the data collected so far are essential for basic astronomical research because there is no longer an instrument that extensively maps the sky in this wavelength range (typically 60 to 200 micrometres). The now active James Webb Space Telescope observes in the infrared at shorter wavelengths and focuses on spatially small areas. Therefore, the analysis of the data collected by SOFIA is ongoing and continues to provide important insights – also regarding other star-forming regions: “In the list of FEEDBACK sources, there are other gas clouds in different stages of evolution, where we are now looking for the weak CII radiation at the peripheries of the clouds to detect similar interactions as in the Cygnus X region,” Schneider concluded.
Press and Communications Team: Jan Voelkel
Understanding more precisely how stars form from interstellar molecular clouds is one of the most pressing astrophysical questions. NASA's James Webb Space Telescope is now providing spectacular new images of the Orion Nebula, a very active birthplace of young stars in our immediate neighborhood.
Together with an international team of experts, researchers from the I. Physikalisches Institut of the University of Cologne (Yoko Okada and Markus Röllig ) had their first look at the new images. In the coming weeks, they will analyze the data more deeply to decipher the details of star formation in Orion.
An enormous hole 22 meters in diameter has been dug near the summit of Cerro Chajnantor in Chile’s Atacama Desert, at an elevation of 18,400 feet. The hole stands ready for the cement foundation on which the Fred Young Submillimeter Telescope (FYST, pronounced “feest”) will one day rest. The foundation, which was designed in Chile, began construction in the fall of 2021 and is scheduled to be installed at the summit from May to June.
Rotational action spectroscopy is an experimental method in which rotational spectra of molecules,
typically in the microwave to sub-mm-wave domain of the electromagnetic spectrum (B1–1000 GHz),
are recorded by action spectroscopy. Action spectroscopy means that the spectrum is recorded not by
detecting the absorption of light by the molecules, but by the action of the light on the molecules, e.g.,
photon-induced dissociation of a chemical bond, a photon-triggered reaction, or photodetachment of
an electron. Typically, such experiments are performed on molecular ions, which can be well controlled
and mass-selected by guiding and storage techniques. Though coming with many advantages, the application of action schemes to rotational spectroscopy was hampered for a long time by the small energy content of a corresponding photon. Therefore, the first rotational action spectroscopic methods
emerged only about one decade ago. Today, there exists a toolbox full of different rotational action
spectroscopic schemes which are summarized in this review.
During an internship of guest student Julian Fischer, measurements were made at the I. Physikalisches Institut in the working group of Prof. Schlemmer.
The result: a signal reminiscent of the Cologne Cathedral ... which even occurs at 111 GHz.
Normally, the group measures and studies the spectroscopic fingerprints of molecules (especially with astrophysical relevance). Molecules have, comparable to humans, unique fingerprints by which they can be identified. Therefore, molecules in distant galaxies, star forming regions, etc. can be detected by these signatures.
Large-scale [CII] mapping provides new insight into the kinematics of the ISM. The interaction between massive stars and the ISM is probed through [CII] observations. Spectrally resolving the [CII] emission is necessary to probe the microphysics induced by the feedback of massive stars. We show that certain heterodyne instrument data quality issues can be resolved using a spline-based technique, and better data correction routines allow for more efficient observing strategies.
The present Virtual Special Issue (VSI), ”Laboratory Spectroscopy for Astrophysics”, celebrates Stephan Schlemmer’s remarkable contributions to the field of molecular spectroscopy, molecular collisions, and laboratory astrophysics over the last three decades, on the occasion of his 60th birthday on September 7, 2020. This VSI, guest edited by three of the authors (P. J., J. O. and H. M.), contains contributions covering all relevant forms of molecular spectroscopy, in particular involving laboratory astrophysics in the microwave, infrared or XUV part of the spectrum, at high or low resolution.
The German-French programme GENESIS (Generation of Structures in the Interstellar Medium) is a cooperation between the University of Cologne’s Institute for Astrophysics, LAB at the University of Bordeaux and Geostat/INRIA Institute Bordeaux. In a highlight publication of the journal Astronomy & Astrophysics, the research team presents the new mathematical methods to characterize turbulence using the example of the Musca molecular cloud in the constellation of Musca.
Die Hülle eines S-Sterns
Sagittarius A*, das extrem massereiche Schwarze Loch im Zentrum unseres Milchstraßensystems, umkreisen auf engen Bahnen mehrere Dutzend Sterne – die Mitglieder des S-Sternhaufens. Einer von ihnen, der Stern S 50, ist mit einer länglichen Struktur mit der Bezeichnung X 7 verknüpft. Um was handelt es sich dabei?
More than a hundred people gathered virtually at the end of April for the 2021 annual conference on the CCAT-prime project, which is building the Fred Young Submillimeter Telescope (FYST) in Chile. Despite pandemic challenges, telescope planning, development and construction continues, with “first light” now scheduled for 2023.
Der Europäische Forschungsrat (ERC) hat die beiden Kölner Wissenschaftler Professor Dr. Michael Bollig und Professor Dr. Stephan Schlemmer mit dem ERC Advanced Grant ausgezeichnet. Bollig wird für sein Projekt REWILDING mit knapp 2,5 Millionen Euro gefördert. Schlemmer erhält für sein Projekt „MissIons“ ebenfalls Fördergelder in Höhe von 2,5 Millionen Euro. Der ERC Advanced Grant gilt als der wichtigste Förderpreis der europäischen Forschungslandschaft.
Am Südhimmel, etwa 4.300 Lichtjahre von der Erde entfernt, liegt RCW 120, eine riesige leuchtende Wolke aus Gas und Staub. Ein internationales Team, das hauptsächlich von Forschern und Forscherinnen der Universität Köln und der West Virginia University (USA) geleitet wurde, konnte das Alter von RCW 120 auf weniger als 150.000 Jahre eingrenzen, was sehr jung für einen solchen Nebel ist. Die Untersuchungen ergaben, dass die stellare Rückkopplung – ein Prozess, bei dem Sterne Energie zurück in ihre Umgebung abgeben – die Sternbildung in der Umgebung positiv beeinflusst. Diese Erkenntnisse können Aufschluss über die hohe Rate an Sternentstehungen im frühen Stadium unseres Universums geben. Die Ergebnisse dieser Studie sind in der April-Ausgabe der Zeitschrift Science Advances veröffentlicht (Luisi et al. 2021).
Die fliegende Sternwarte SOFIA (das Stratosphären-Observatorium Für Infrarot-Astronomie) hat eine Reihe von Beobachtungsflügen vom Flughafen Köln/Bonn aus erfolgreich abgeschlossen. Mit an Bord waren Wissenschaftlerinnen und Wissenschaftler der Uni Köln und des MPI für Radioastronomie in Bonn, die weitere Erkenntnisse zur Entstehung von neuen Sternen gewinnen konnten
Hoch in den Bergen Chiles, auf dem 5.600 Meter hohen Cerro Chajnantor in der Atacama-Wüste, befindet sich einer der trockensten Orte der Erde. Mithilfe des neu entstehenden Fred Young Submillimeter Telescope (FYST) erhoffen sich Astronomen neue Einblicke in die Entstehung der Sterne und Galaxien in unserem Universum. Forscher und Forscherinnen der Universität zu Köln unter Leitung von Professor Dr. Jürgen Stutzki sind an dem internationalen Konsortium von Wissenschaftlern beteiligt. Durch die Finanzierung der kanadischen Kooperationspartner mit 4,9 Millionen Dollar durch die Canada Foundation for Innovation ist das Projekt jetzt auf sichere Füße gestellt.