Beobachtungen mit dem IRAM-Teleskop
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Measurement Campaign at the IRAM Telescope, Spring 2013
In the spring of 2013, we conducted two one-week observation campaigns at the IRAM telescope in the Sierra Nevada, Spain, to search for simply deuterated hydrogen peroxide in the interstellar medium.
The IRAM telescope (Institute for Radio Astronomy in the Millimeter Range), with a diameter of 30 meters and a surface accuracy of 55 micrometers, is one of the largest and most sensitive radio telescopes in the world. Its location on a mountain in the Sierra Nevada, Spain, at an altitude of 2,850 meters guarantees good weather conditions for astronomical observations.
We have an interesting master’s thesis opportunity available for this project. You can also contact the supervising Doctoral candidate, Doris Herberth, or Prof. Thomas Giesen.
Photo gallery of the measurement campaign:
Brochure on the IRAM telescope
Measurement Campaign at the IRAM Telescope, 2008
In 2008, we conducted a measurement campaign at the IRAM telescope in the Sierra Nevada in Spain with the goal of detecting the molecule corannulene (C20H10) in interstellar space.
Corannulene belongs to the group of polycyclic aromatic hydrocarbons (PAHs). There is a theory that this group of molecules is responsible for the so-called “diffuse interstellar bands.” These are absorption bands that can be observed in the spectra of a wide variety of objects in our galaxy. According to this theory, they are caused by molecules that occur in many regions of our galaxy. Nevertheless, the molecular group responsible for these absorption bands has not yet been identified.
Most PAHs do not have a permanent dipole moment. However, this is a prerequisite for molecules to be excited into rotation by electromagnetic radiation.
Corannulene is an exception in this regard, as it is not “flat,” like the vast majority of PAHs, but rather has a bowl-shaped structure. For this reason, it possesses a dipole moment and thus a rotational spectrum, which allows it to be unambiguously detected in the interstellar medium. Given the similar formation processes, one can also expect numerous other PAHs to be present in regions where corannulene occurs, so that the detection of corannulene would simultaneously serve as evidence for the presence of PAHs in general.
In preparation for the astronomical measurements, the molecule’s rotational spectrum was first studied in the laboratory, which always serves as the basis for astronomical detection. In collaboration with observational astronomers, we then searched for an interstellar source where a sufficient concentration of corannulene was suspected to exist for detection. We chose the carbon-rich protoplanetary nebula “Red Rectangle,” located in the vicinity of the binary star HD 44179. We then performed a simulation of the emission spectrum of UV-excited corannulene under the conditions of this interstellar environment, thereby meeting all the prerequisites for conducting the observation campaign.
The measurement campaign at the IRAM telescope took place in February 2008. Observation time at this radio telescope is usually scheduled for the winter, as observation conditions are best at this time of year due to lower humidity.
We searched for various spectral lines of the molecule in the millimeter wavelength range. None of the spectral lines we were looking for could be detected in the astronomical spectra. However, the observations allowed us to derive an upper limit on the abundance of corannulene in the Red Rectangle.