Heidelberg Joint Astronomical Colloquium
Frank Snik (University of Leiden, NL)
Title: Advanced optical instrumentation for the characterization of habitable planets, including our own Earth
Abstract:
To directly image and characterize exoplanets, we need advanced optical systems on current and future telescopes that can suppress the bright glare of stars by 6-10 orders of magnitude, and analyze the feeble light of potential planetary companions. Such high-contrast imaging systems consist of advanced adaptive optics and associated wavefront sensing techniques, coronagraphy to (locally) suppress the diffracted starlight, contrast-enhancing techniques like angular/spectral/polarimetric differential imaging, and diagnostic capabilities like (high-resolution) spectroscopy and (spectro)polarimetry. In our group in Leiden we combine all these different aspects of high-contrast imaging, with the aim to achieve the ultimate contrast performance and characterization potential. We are currently exploiting brand-new liquid-crystal technologies that offer important performance benefits for coronagraphy, and for the system as a whole. We have currently installed our “vector-APP” coronagraph at MagAO, LBT, SCExAO, and the stratospheric balloon telescope HiCIBaS, and are developing versions for several other telescopes on the ground and in space. To prepare for our ultimate goal of directly characterizing the atmosphere and surface of a habitable exoplanet and potentially detecting signs of life, we are developing instruments to provide benchmark data for the only planet currently known to harbor life: our own Earth. We have recently performed field measurements of the most compelling biomarker: circular polarization due to homochirality of biological molecules. We are currently building instruments to map biomarkers for our planet as a whole from the ISS and from the moon. As a spin-off of all these activities, we are developing remote-sensing approaches for measuring the pollution in our own atmosphere. The instrument SPEXone, based on our spectropolarimetric technology, has been selected for NASA’s next large Earth-observation satellite to measure the influence of aerosol particles on our climate and health. We have even applied the same technique on smartphones (iSPEX), and are collaborating with an army of citizen scientists to perform measurements of air and water pollution.
