Smallest exoplanet directly imaged

Exoplanets are an exciting new field of research. In less than twenty years, the number of known exoplanets has exploded from zero to almost a thousand, with almost three thousand potential candidates waiting to be confirmed. But these have all been discovered indirectly, usually using the radial velocity or transit methods, because direct imaging of an exoplanet is so difficult. Planets are incredibly small on a cosmic scale, mere motes of dust, and they’re impossibly far away. Adding to the challenge is the fact that they only shine dimly by reflected light, making them even harder to see against the glare of their parent stars. This is why only a handful of exoplanets have ever been directly imaged, and only ever by astronomers using the most advanced technology who know exactly where to look.
The VLT is a compound telescope made of four giant telescopes with 8.2 meter apertures, working in unison. It uses the very latest in adaptive optics technology, beaming a high powered laser into the sky to create an artificial star which sophisticated sensors monitor to map atmospheric distortions many times each second. High speed computers drive actuators which flex and distort the mirrors to cancel out those distortions, allowing the telescope to see almost as clearly as an equivalent sized space telescope. The Hubble Space Telescope, at 2.5 meters, is less than a third the size of one single element of the VLT.
HD 95086 is an extremely young star, with an age somewhere between ten and seventeen million years. It is still surrounded by a ring of gas and dust, which makes it particularly interesting to planetary scientists. By studying this ring, and the exoplanet which moves within it, we can improve our understanding of how planets form, and how they migrate to their final orbits.
HD 95086 is an A-class pre-main sequence star, which shines extremely brightly. Even at such a far orbital distance, the exoplanet should have an average surface temperature of seven hundred degrees Celsius. This means that gases like water vapour and methane could exist within its atmosphere. Astronomers hope to study this further when the new SPHERE instrument (an even more sophisticated second generation adaptive optics system) is fitted to the VLT later this year.
For more information, read the paper announcing the discovery on arXiv at: arXiv:1305.7428 [astro-ph.EP]