Saturday 21 September 2013

A superjovian exoplanet directly imaged orbiting the A-class pre main-sequence star HD 95086.

HD 95086 is an A-class pre main-sequence star (young star which has not yet begun to fuse hydrogen, but which is emitting energy due to gravitational contraction) in the constellation of Carina, 295 light years from the Earth. It is believed to be between 10 and 17 million years old, has a mass 1.6 times that of the Sun, and has previously been shown to be surrounded by a debris disk (ring of asteroidal or cometary material).

In a paper published on the online arXiv database at Cornell University Library on 30 August 2013, a team of scientists led by Julien Rameau of the Institut de Planétologie et d’Astrophysique de Grenoble at Université Joseph Fourier describe the discovery of a planet orbiting HD 95086 by direct imaging with  the Nasmyth Adaptive Optics System Near-Infrared Imager and Spectrograph on the Very Large Telescope on Cerro Paranal in the Atacama Desert of northern Chile.

The planet is assigned the name HD 95086b, making the star HD 95086A; when naming objects in other stellar systems astronomers give upper case letters to stars and lower case letters to planets. It is thought to have a mass 4-5 times that of Jupiter, making it the smallest exoplanet yet discovered by direct imaging, and to orbit HD 90586A at a distance of 56 AU, i.e. it is 56 times as far from its parent star as the Earth, or nearly twice as far as Neptune.

Infra-red image of HD 95086b made using the Nasmyth Adaptive Optics System Near-Infrared Imager and Spectrograph on the Very Large Telescope in the Atacama Desert of northern Chile. Rameau et al. (2013).

The HD 95086 system was observed at infra-red wavelengths in January 2012 and February and March 2013, in order to confirm that the movement of the two bodies relative to one-another.

Chart of the Carina Constellation showing the position of the HD 95086 system (center of red circle). European Southern Observatory.

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