Research Projects

Polarimetry of planets

• polarimetric studies of solar system planets and moons
• simulation of the polarized radiation from planets
• polarimetric search of extra-solar planets

Light reflected by planets can be polarized due to Rayleigh scattering by molecules, due to Mie scattering by haze particles, or due to refraction and reflection from droplets in clouds. The intensity and the degree and position angle of polarization of the scattered light depends on the particle properties, the scattering angle, the wavelength, and the optical depth of the scattering atmosphere. Polarimetry is therefore a powerful technique to investigate the structure of planetary atmospheres and the properties of the scattering particles therein. Polarization studies are also considered to be a desirable technique for the search and investigation of extra-solar planets. Polarimetry is a very sensitive technique to distinguish between the unpolarized light coming directely from a star and the scattered an therefore polarized light from a nearby planet. For this reason there could be extra-solar planets which are better searched and characterized with polarimetry first. The ultimated goal of all these investigations is the detection of signs of biological life in other stellar systems.

SPHERE, the VLT Planet Finder

The Institute of Astronomy of the ETH is part of an international consortium which builds the "SPHERE Planet Finder" instrument for an 8m VLT telescope of the European Southern Observatory (ESO). SPHERE shall be operational in 2012 and then search during several hundred nights for planets around nearby stars. For this instrument we are building the Zurich IMaging POLarimeter (ZIMPOL), a camera designed to detect the reflected and therefore polarized light from extra-solar planets and circumstellar dust disks.

EPICS, the E-ELT Planet Finder

• responsible for studies on the EPICS polarimeter
• member in the EPICS science team

We are participating in the feasibility study for the EPICS Planet Finder for the E-ELT project. E-ELT is the European Extremely Large Telescope, a project of the European Southern Observatory (ESO) for a future gigantic 42m telescope. This telescope project is currently in the design phase and feasibility studies are carried out for possible focal plane instruments. The E-ELT is the highest priority project of ESO and if everything goes well a realization before 2020 seems possible.

Teaching

Publications

Previous positions

• 1986-1993 Institute for Astronomy, ETH Zürich, Switzerland
• 1993-1996 Mount Stromlo and Siding Spring Observatories, Canberra, Australia
• 1997-2001 Landessternwarte, Heidelberg, Germany