Tau.Neutrino said:
The image of PDS 70b around the young dwarf star PDS 70
SPHERE – Spectro-Polarimetric High-contrast Exoplanet REsearch
SPHERE is the extreme adaptive optics system and coronagraphic facility at the VLT. Its primary science goal is imaging, low-resolution spectroscopic, and polarimetric characterization of extra-solar planetary systems at optical and near-infrared wavelengths.
One major obstacle to directly imaging a distant exoplanet is that the light of any star is so powerful from our point of view that something close to it, like a planet orbiting the star, is swamped by the starlight. SPHERE is designed to exploit a clever way of suppressing the stellar light contribution. It turns out that the light emitted naturally by stars is unpolarised, meaning that the electromagnetic waves oscillate randomly in different directions. But when light is reflected by a surface (such as a planet or a dusty disc), the reflected waves are polarised.
there are three important stages in extracting the direct image of a planet. First, a state-of-the-art adaptive optics system has been incorporated into the instrument to correct for the turbulent effects of the Earth’s atmosphere with the aim of delivering images as sharp as if the telescope were floating in space. Secondly, a coronagraph is used to block out the light from the star itself and increase the contrast still further. Finally, a technique called differential imaging is applied that exploits differences (the filters) between planetary and stellar light in terms of colour or polarisation.
The instrument was installed and achieved first light in June, 2014.