Astronomers using ESO’s Very Large Telescope have captured an image of a faint object circling the young, dusty, early-type star HD 95086. With a mass of 4 to 5 times greater than Jupiter’s, the object would be the least massive planet to be directly imaged outside the Solar System.
This image shows the exoplanet candidate HD95086 b (ESO / J. Rameau)
“Direct imaging of planets is an extremely challenging technique that requires the most advanced instruments, whether ground-based or in space,” explained Dr Julien Rameau from the Institut de Planetologie et d’Astrophysique de Grenoble, France, lead author of a paper accepted for publication in the Astrophysical Journal Letters (arXiv.org version).
“Only a few planets have been directly observed so far, making every single discovery an important milestone on the road to understanding giant planets and how they form.”
The newly detected planet candidate, called HD95086 b, appears as a faint but clear dot close to its host star. A later observation showed that it was slowly moving along with the star across the sky. This suggests that the object is in orbit around the star. Its brightness also indicates that it has a predicted mass of 4 to 5 times that of Jupiter.
The star HD 95086 is just 10 to 17 million years old, and located in the southern constellation of Carina about 300 light-years away.
According to the study, HD95086 b orbits the star at a distance of about 56 AU (astronomical units).
The star itself is a little more massive than the Sun and is surrounded by a debris disc. These properties allowed the team to identify it as an ideal candidate to harbor young massive planets.
The youth of HD 95086 leads astronomers to believe that HD95086 b probably formed within the gaseous and dusty disc that surrounds the star.
“Its current location raises questions about its formation process,” noted co-author Dr Anne-Marie Lagrange, also from the Institut de Planetologie et d’Astrophysique de Grenoble.
“It either grew by assembling the rocks that form the solid core and then slowly accumulated gas from the environment to form the heavy atmosphere, or started forming from a gaseous clump that arose from gravitational instabilities in the disc.”
“Interactions between the planet and the disc itself or with other planets may have also moved the planet from where it was born.”
“The brightness of the star gives HD 95086 b an estimated surface temperature of about 700 degrees Celsius. This is cool enough for water vapor and possibly methane to exist in its atmosphere. It will be a great object to study,” concluded co-author Dr Gaël Chauvin.
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Bibliographic information: J. Rameau et al. 2013. Discovery of a probable 4-5 Jupiter-mass exoplanet to HD 95086 by direct-imaging. ApJ L, accepted for publication; arXiv: 1305.7428
