Astronomy
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ASTRONOMY At Stockholm Observatory, imaging investigations of the physical structures of circumstellar disks, primarily debris disks, are carried out using telescopes in the optical, far-infrared, and sub-mm wavelength regions, in order to better determine how disks evolve with time, and find similarities to our own Solar system. Sub-mm observations with LABOCA on APEX has been used to study a number of main-sequence stars with known ages and inferred disks (from mid- to far-infrared excess) at 870 µm, to probe extended, cold dust components (out to some hundreds of AU), in order to assess the existence, extent and mass of Kuiper-Belt-like disk structures. Together with the fairly accurately known ages of the stars, evolutionary aspects of the disks can be studied. In another project, properties of circumstellar dust disks are examined with a polarizing coronagraph instrument, where the direct light from the star is blocked out, making the faint scattered optical light from the disk detectable. By inserting a polarizing filter in different orientations, the angle and degree of polarization can be calculated and used to further enhance the contrast. This high-contrast imaging of low surface-brightness features can reveal gaps, knots, and asymmetries in the disks, perhaps indicating planets. In addition to observational projects, theoretical studies and simulations of disks are carried out at the department. |