* Astronomy

Imaging Polarimetry of Circumstellar Environments with ExPo

A team of Dutch astronomers designed and built the innovative imaging polarimeter ExPo (the Extreme Polarimeter), which is a regular visitor instrument at the William Herschel Telescope (WHT). ExPo was designed and built at Utrecht University and has, due to the closure of astronomy in Utrecht, moved to Leiden University.
ExPo makes use of polarised light to study the faint, dust-rich environments around young and evolved stars. The advantage of using polarimetry, over normal intensity images, is that the unpolarised light from the star is easily removed, allowing directly observation of the star's surroundings in scattered (linearly polarised) light. The information contained in the polarised light constrains the properties of the scattering particles (dust), such as their size, albedo and structure.
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