Infrared Astronomy

The research group uses infrared interferometry to investigate the physical properties of young stars, stars in later stages of development and active galactic nuclei in the visual and infrared spectral region.

The Institute develops new methods and instruments for infrared interferometry and spectroscopy.

Note on interferometry:

Interferometry is the superposition of waves. The method has been used for a long time in radio astronomy. In contrast to optical astronomy, there is no need here to directly superimpose the signals of the telescopes; instead, the complete wave information from each individual telescope is recorded in terms of amplitude and phase. If the exact time is also known, the signals of all telescopes can be made to interfere in the computer. Radio telescopes on different continents can thus be linked together (Very Long Baseline Interferometry).

Interferometry in the infrared and visible light regions is much more difficult to perform because, on the one hand, both the wavelength and the coherence length are significantly smaller, and, on the other, it is not possible to record the phase of the light, only the brightness information.

Note regarding resolution:

Interferometry aims to obtain high-resolution images of astronomical objects. This is because the resolution achieved depends on the aperture of the telescope and on the wavelength. A radio telescope with the resolving power of an optical 60-millimetre telescope requires an antenna diameter of 1.2 kilometres!

Research Topics

• Infrared spectral interferometry with milliarcsecond angular resolution and high spectral resolution

• Infrared aperture synthesis imaging of young and evolved stars

• Polarimetry of young stars

• High-resolution measurements of surface structures on stars, mass loss and dust envelopes of  giants, supergiants and AGB stars

• Infrared aperture synthesis interferometry of giants and B[e] stars

• Spectral interferometry and spectroscopy of LBV stars

• Infrared interferometry with milliarcsecond resolution of AGN tori

• Development of radiation transport models for the detailed interpretation of interferometric measurements

• Participation in instrumentation projects: VLTI/AMBER, LBT/LINC-NIRVANA, VLTI/MATISSE and ARGOS for LBT