Astronomers have discovered thousands of exoplanets, but few have been directly imaged as most end up drowning in the brightness of their planets. star. A University of Hawaii student recently isolated a planet far enough from its host to be seen directly. You will find it "only" 35 light years from Earth.
The detection of exoplanets is essentially based on two methods. The first, that of transit, aims to detect dips in stellar luminosity, testifying to the passage of an exoplanet in front of its star from our point of view. The second, that of radial velocity, is based on changes in the wavelength of light from a star. Concretely, a planet evolving around a star exerts a slight gravitational influence which causes it to wobble slightly. The wavelength of its light then shifts as it approaches and moves away from us. For astronomers, this "wobble" therefore testifies to the presence of a planet.
These two methods are ideal for detecting massive exoplanets close to their star, because the signal indicating their presence will be larger and easier to discern. On the other hand, the fact that these planets are so close to their star implies that they are not directly visible, the latter beingdrowned in the luminosity of their host .
However, sometimes worlds are far enough from their star to be directly visible. Such is the case with this new discovery, the details of which are reported in The Astrophysical Journal Letters.
As part of a survey called COol Companions ON Ultrawide orbits (COCONUTS) which aimed to find planets moving at a great distance from their star, while being close to Earth , Zhoujian Zhang, a student at the University of Hawaii, stumbled upon a world six times more massive than Jupiter moving more than 6,400 Astronomical Units (AU) from its star.
At this distance, its orbital period is approximately 1.1 million years , which could be a record for a known exoplanet.
Baptized COCONUTS-2b, this planet was first detected in 2011 by the Wide-field Infrared Survey Explorer satellite, but at the time it was thought to be was a free-floating object, not a planet orbiting a star.
As part of his thesis, Zhang and his collaborators pointed out that this object was actually gravitationally bound to a low-mass star about three times less massive than Sun and about ten times younger. You will find all these beautiful people about 35 light years away of the Earth.
Formed only 800 million years ago approximately, COCONUTS-2b is the second coldest imaged exoplanet found to date, with a temperature of just 161°C. This photo was obtained thanks to the light emitted by the planet, produced by the residual heat trapped since its formation.
