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Universität zu Köln
Mathematisch-Naturwissenschaftliche Fakultät
Fachgruppe Physik

I. Physikalisches Institut

Klaus Liebrecht price 2014

(Bild: © Patric Foud)

Marc Peter Westig received the Klaus Liebrecht dissertation price of the Faculty of Mathematics and Natural sciences of the University of Cologne for the year 2014. In his PhD thesis with the title "Quantum limited balanced superconducting 380-520 GHz mixer on a silicon membrane and mesoscopic tunnel devices for terahertz frequencies", he worked on new detector circuits for astronomical applications and on device physics aspects of superconductors out of thermal equilibrium. Key results of his thesis include the experimental proof of the first on-chip superconducting balanced mixer at 500 GHz with quantum limited performance and a new hybrid SIS junction technology, suitable for terahertz frequencies.

(fsc 2015-02-12)

Astrochemical Dating of a Stellar Nursery

An international research team led by scientists from the Coordinated Research Center (CRC) 956 “Conditions and Impact of Star Formation” at the University of Cologne has used observations made with the GREAT instrument on board the SOFIA aircraft observatory and the APEX telescope to date the core of an interstellar cloud that is forming a group of Sun-like stars. This work, to which scientists from the University of Helsinki as well as from the Max-Planck-Institutes for Radio Astronomy (MPIfR) and Extraterrestrial Physics (MPE) contributed, is published in this week’s Nature journal.

More information can be found in the Press Release of the Universität zu Köln.

Scientific Publication: “H2D+ observations give an age of at least one million years for a cloud core forming Sun-like stars”, Nature (2014)
by Sandra Brünken, Olli Sipilä, Edward T. Chambers, Jorma Harju, Paola Caselli, Oskar Asvany, Cornelia E. Honingh, Tomasz Kamiński, Karl M. Menten, Jürgen Stutzki, Stephan Schlemmer

Further Informations:

MPIfR:The Age of Stellar Nurseries
MPE: Astrochemical Dating of a Stellar Nursery
DSI: SOFIA Observations Help Determine the Age of a Star Nursery
DLR: Age of star nursery precisely determined for the first time
Science News: Young suns took at least 900,000 years to arise
Further figures:

Das Alter von stellaren Kinderstuben

Astrochemische Altersbestimmung durch Moleküllinienbeobachtungen mit SOFIA und APEX

Ein internationales Forscherteam unter der Leitung von Wissenschaftlern des Sonderforschungsbereichs 956 „Bedingungen und Auswirkungen der Sternentstehung“ an der Universität zu Köln hat Beobachtungsdaten vom GREAT-Empfänger an Bord des Flugzeug-Observatoriums SOFIA sowie vom APEX-Teleskop in Chile dazu verwendet, das Alter eines Sternentstehungsgebiets in einer interstellaren Wolke genau zu bestimmen. Im Zentrum der Wolke entsteht eine Gruppe von sonnenähnlichen Sternen. Das Resultat, zu dem auch Wissenschaftler von der Universität Helsinki sowie der beiden Max-Planck-Institute für Radioastronomie (Bonn) und für extraterrestrische Physik (Garching) beigetragen haben, wird in der aktuellen Ausgabe der Zeitschrift „Nature“ veröffentlicht.

Mehr Informationen in der Pressemitteilung der Universität zu Köln.

Wissenschaftlicher Artikel: “H2D+ observations give an age of at least one million years for a cloud core forming Sun-like stars”, Nature (2014)
von Sandra Brünken, Olli Sipilä, Edward T. Chambers, Jorma Harju, Paola Caselli, Oskar Asvany, Cornelia E. Honingh, Tomasz Kamiński, Karl M. Menten, Jürgen Stutzki, Stephan Schlemmer

Weitere Informationen:

MPIfR:Das Alter von stellaren Kinderstuben
MPE: Das Alter von stellaren Kinderstuben
DSI: SOFIA hilft bei der Altersbestimmung von stellaren Kinderstuben
DLR: Wie lange dauert die Geburt eines Sterns?
Weitere Bilder:

(sbr 17-11-2014)

Interstellare Moleküle verzweigen sich

Eine Gruppe Wissenschaftler vom Max-Planck-Institut für Radioastronomie in Bonn, von der Universität zu Köln und von der Cornell University in Ithaca, NY, USA haben das erste Molekül mit verzweigtem Kohlenstoffgerüst im All entdeckt. Die Wissenschaftler führten eine Liniendurchmusterung von Sagittarius (kurz: Sgr) B2(N) bei 3 mm Wellenlänge mit dem Atacama Large Millimeter Array (ALMA) in Chile durch. Dabei fanden sie erstmalig iso-Propylcyanid. Diese Entdeckung, so wie eigene Modellrechnungen deuten darauf hin, dass verzweigte Moleküle recht gewöhlich im All sein könnten. Möglicherweise lassen sich bald noch komplexere Moleküle, wie z.B. Aminosäuren, finden, die bei der Enstehung des Lebens auf der Erde, und vielleicht auch anderswo, eine wichtige Rolle gespielt haben könnten.

Sgr B2(N) ist eine riesige Molekülwolke in der Nähe des Zentrums der Milchstraße, in der viele massereiche Sterne entstehen und in der viele Moleküle entdeckt wurden. Die Gruppe entdecke bereits früher das Isomer n-Propylcyanid, Ethylformiat und Aminoacetonitril. Letzteres könnte als Vorläufer für Glycin, der einfachsten Aminosäure, dienen.

Highlights der Laborspektroskopiegruppe.
Pressemitteilungen des MPIfR in Bonn und der Universität zu Köln.
A. Belloche, R. T. Garrod, H. S. P. Müller und K. M. Menten, Detection of a Branched Alkyl Molecule in the Interstellar Medium: iso-Propyl Cyanide, Science 345 (2014) 1584–1587.

Interstellar Molecules are branching out

A group of scientists from the Max-Planck-Institut für Radioastronomie in Bonn, from the Universität zu Köln, and from the Cornell University in Ithaca, NY, USA have detected in space the first molecule with a branched carbon backbone. The scientists carried out a line survey of Sagittarius (short: Sgr) B2(N) at 3 mm wavelength employing the Atacama Large Millimeter Array (ALMA) in Chile. They detected for the first time iso-propyl cyanide. This detection as wel as own model calculations suggest that branched molecules could be quite common in space. It may well be that even more complex molecules, such as aamino acids, will be detected in space. These molecules may have played a prominent role for the formation of life on Earth and possibly elsewhere.

Sgr B2(N) is giant molecular cloud close to the center of Milkyway, in which many high-mass stars are being formed and in which many molecules have been detected. The group detected previously the isomer n-propyl cyanide, ethyl formate and aminoacetonitril. The latter could act as a precursor for glycine, the simplest amino acid.

Highlights of the laboratory spectroscopy group.
Press release of the MPIfR in Bonn.
A. Belloche, R. T. Garrod, H. S. P. Müller und K. M. Menten, Detection of a Branched Alkyl Molecule in the Interstellar Medium: iso-Propyl Cyanide, Science 345 (2014) 1584–1587.
(HSPM, 2014-10-06

Measurement of a very accurate transition frequency (1 ppb) of an anion by action spectroscopy

P. Jusko, O. Asvany, A.-C. Wallerstein, S. Brünken, and S. Schlemmer
report in this weeks Physical Review Letters on
Two-Photon Rotational Action Spectroscopy of Cold OH at 1 ppb Accuracy.

An IR-THz double-resonance light induced reaction (LIR) depletion technique was employed to record the fundamental rotational transition J = 1 – 0 of OH near 1.123 THz in a 4 K 22-pole ion trapping machine with an accuray of 1.4 kHz or about one part in a billion. An improvement in accuracy of more than two orders of magnitude was achieved with respect to the previous laboratory measurement.

The article was highlighted as editors' suggestion in PRL.

(hspm 2014-06-27)

Ubiquitous argonium (ArH+) in the diffuse ISM (P. Schilke et al.)

A molecular tracer of almost pure atomic gas

In section 6. Interstellar and circumstellar matter

by P. Schilke, D. A. Neufeld, H. S. P. Müller, et al., A&A 566, A29

It is not entirely unexpected to find that a molecular ion is a tracer for diffuse atomic ISM clouds. It has been known for some time that ions such as HCO+ observed in absorption against the background of point-like radio sources trace low-density, mainly atomic material. More recently, ions such as H2O+ have been detected with Herschel. Nevertheless, it is a surprise to find that argonium (ArH+) can be detected not only in the Crab nebula but also (as shown in the article by Schilke et al.) in clouds along the line of sight to various strong submm sources in the Galactic plane. It is also surprising to find that, based on the diffuse cloud chemistry models, ArH+ likes to live in clouds with a molecular fraction 2n(H2)/n(HI) of approximately 10–3. All molecules are not alike !

The article was marked as Highlight of the week by Astron. Astrophys.

GREAT Far-IR Spectrometer Opens Window to New Science Opportunities

With successful commissioning of its high-frequency channel, the GREAT (German Receiver for Astronomy at Terahertz Frequencies) far-infrared spectrometer onboard SOFIA is ready to explore new realms.

Figure 1: First-light observations by the GREAT H-channel on SOFIA: map of planetary nebula NGC 7027 in the neutral oxygen emission line at 63 microns. The effective angular resolution is indicated by the gray circle at lower left. (Credit: GREAT Consortium)
Figure 2: High-resolution spectrum of OI toward the center of NGC 7027 showing complex velocity structure in the outflow. (Credit: GREAT Consortium)

The new so-called H-channel was first tested during SOFIA flights on May 5, 6, and 7, and confirmed to be working perfectly. It is based upon an extremely sensitive superconducting detector, developed and built at KOSMA, I. Physikalisches Institut, University of Cologne and a novel terahertz laser, a so-called quantum cascade laser. With that receiver added, the GREAT instrument is now capable of high-resolution spectroscopy of astrophysically important lines of atomic neutral oxygen [OI] at a wavelength of 63 μm ( frequency of 4.74 TeraHertz).

First-light spectra were obtained towards planetary nebula NGC 7027 (Figure 1). That nebula is an expanding bubble of gas expelled by a dying star with approximately the mass of our Sun, 3,000 light-years away in the constellation of Cygnus. The nebula has been extensively studied at other wavelengths, but only GREAT can resolve the velocities of the expanding envelope in the OI line. The spectrum (Figure 2) represents only 2 minutes of integration, illustrating the superb sensitivity of the GREAT instrument carried into the stratosphere by SOFIA.

GREAT is a Principal Investigator-class instrument for SOFIA, developed and maintained by the Max Planck Institute for Radio Astronomy (PI: Rolf Guesten) and KOSMA at the University of Cologne (Co-I: Juergen Stutzki), in collaboration with the DLR Institute of Planetary Research (Co-I: Heinz-Wilhelm Huebers) and the Max Planck Institute for Solar System Research (Co-I: Paul Hartogh).

SOFIA is a joint project of NASA and the German Aerospace Center (DLR). The aircraft is based at NASA Armstrong Flight Research Center that manages the program. NASA Ames Research Center at Moffett Field, Calif., manages the SOFIA science and mission operations in cooperation with the Universities Space Research Association (USRA) headquartered in Columbia, Md., and the German SOFIA Institute (DSI) at the University of Stuttgart.

For more information about SOFIA, visit:

For information about SOFIA's science mission, visit:

For information about GREAT, visit:


(fsc 2014-06-11)

SOFIA fliegt nach Süden

Deutsch-amerikanisches Flugzeug-Observatorium wird jenseits des Äquators in Neuseeland eingesetzt

SOFIA, das vom Deutschen Zentrum für Luft- und Raumfahrt (DLR) und der NASA gemeinsam betriebene "Stratosphären - Observatorium für Infrarot- Astronomie", fliegt erstmals in der südlichen Hemisphäre: Ziel der dreiwöchigen Stationierung am Flughafen Christchurch in Neuseeland ist die Untersuchung von Himmelskörpern, die nahezu ausschließlich von Flugrouten südlich des Äquators zu beobachten sind. Beim ersten der insgesamt neun geplanten Wissenschaftsflüge nahmen die deutschen und amerikanischen Forscher während des zehnstündigen Fluges in der Nacht vom 17. auf den 18. Juli 2013 (Ortszeit) zwei Nachbargalaxien der Milchstraße, die Magellanschen Wolken, sowie die um das Schwarze Loch im Zentrum unserer Galaxis rotierende Gasscheibe ins Visier. Bei diesen Flügen kommt der deutsche GREAT-Empfänger zum Einsatz, der von einem Konsortium deutscher Forschungsinstitute unter der Leitung von Rolf Güsten vom Bonner Max-Planck-Institut für Radioastronomie entwickelt und betrieben wird.

Presseinformation des Max-Planck-Institut für Radioastronomie
Press Release Max Planck Institute for Radio Astronomy
GREAT - the SOFIA high-frequency heterodyne instrument
Presseinformation der Universität zu Köln
DLR Nachrichten: SOFIA erkundet den Südhimmel über Neuseeland
Deutsches SOFIA Institut (DSI): SOFIA erkundet den Südhimmel über Neuseeland
Informationsdienst Wissenschaft (idw): SOFIA fliegt nach Süden
Spiegel online Wissenschaft: Fliegendes Teleskop "SOFIA" erkundet den Südhimmel
Universities Space Research Association (USRA): NASA's SOFIA Investigates the Southern Sky from New Zealand
NASA News; Dryden News Release 13-19: SOFIA Investigates Southern Sky From New Zealand

(fsc 2013-07-18)

SOFIA ist unterwegs nach Neuseeland. Next stop Christchurch, New Zealand.

SOFIA will travel to Christchurch, New Zealand, from July 12 to Aug. 2, 2013, for three weeks of observations of the southern sky. The scientific targets for the southern deployment of SOFIA include the center of our Milky Way Galaxy, young stars, star forming regions, and supernova remnants in the southern Milky Way, the Milky Way's two satellite galaxies known as the Magellanic Clouds, and several nearby galaxies.



Universities Space Research Association (USRA) Press Kit
TVNZ, NASA observatory lands in Christchurch
Flickr  gallery from SOFIA in New Zealand
Radio New Zealand

LiveTracker of SOFIA, SOFIA Cycle 1 OC1-C; Flight 1
LiveTracker, SOFIA Cycle 1 OC1-C; Flight 2
LiveTracker, SOFIA Cycle 1 OC1-C; Flight 3

(fsc 2013-07-13)