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Home > Les actualités > First discovery of an exoplanet by direct imaging with SPHERE

 First discovery of an exoplanet by direct imaging with SPHERE

Publication date : 6 July 2017

Installed since 2014 on the Very Large Telescope (VLT) of the European Southern Observatory (ESO) in Chile, the European SPHERE instrument has captured an image of an exoplanet for the first time using direct detection methods. To this day, only a handful of the 3,600 exoplanets detected since 1995 have been observed directly. With a mass 6 to 12 times that of Jupiter, HIP65426b is a young massive planet orbiting around a bright star in rapid rotation, located in the Scorpius-Centaurus stellar association. This discovery, which raises new questions about the formation of extrasolar systems, was made by an international team of scientists including researchers from Laboratoire d’Astrophysique de Marseille (LAM). The discovery will be published in the journal Astronomy & Astrophysics.



HIP 65426 b is the first exoplanet to be imaged by the SPHERE instrument using direct detection methods. Located 385 light-years away from the Solar System, in the Scorpius-Centaurus Association, this gas giant lies distant from its star: three times the distance between the Sun and Neptune, the farthest planet in our Solar System, over 14 billion kilometres away. "This is a major discovery!" gladly announces Arthur Vigan, CNRS researcher at LAM and one of the lead authors of this discovery. "We have already observed several hundreds of stars and this is the first new planet that we detect". Its estimated mass is 6 to 12 times that of Jupiter and its estimated temperature between 1,000-1,400 degrees Celsius. Its spectrum reveals the existence of water in its atmosphere and the probable presence of clouds – characteristics found on previously imaged exoplanets. "We are now going to study it and compare it to the other directly imaged giant exoplanets", adds Arthur Vigan.

The planet’s star, HIP 65426, which is twice the size of the Sun, does not appear to be surrounded by a debris disk, as is the case with most young exoplanet systems. Surprisingly, this star rotates very quickly, raising questions as to the origin and formation of planet HIP 65426 b. Researchers have established two possible scenarios to explain this unique system. The exoplanet may have been formed in a disk of gas and dust; when the disk dissipated, it interacted with other planets to move to such a distant orbit. Or, the star and planet may have both formed within an extreme binary star system, where two stars formed simultaneously but one, bigger star, prevented the other from completing its accretion phase and the latter became the planet HIP 65426 b.

The primary objective of the SPHERE instrument, installed on the VLT since 2014, is to use direct imaging to detect and study gaseous exoplanets and disks of dust around stars located near the Sun (within a few hundred light-years) with unparalleled high precision and contrast. It is a daunting task: such planets are located very close to their parent stars and known to emit little light. SPHERE can detect the signal of a planet up to a million times weaker than that of its parent star. By comparison, the instrument could detect, from Paris, the light of a candle 50 cm from a lighthouse in Marseille (775 km away).

The new discovery was largely enabled by the IRDIS camera and spectrograph of SPHERE, which was entirely developed at LAM. This is a huge success for the team of engineers and astronomers from LAM that has designed this camera, as well as many other key elements of SPHERE. "This is the result of more than 10 years of intense work on this amazing instrument" comments Kjetil Dohlen, the system engineer of SPHERE and IRDIS.

SPHERE is equipped with a deformable mirror that corrects for atmospheric turbulence over nanometric scales at over 1,200 times per second. The instrument also uses coronography to attenuate the light of the star and reveal that of the planet. Lastly, imaging and spectroscopy techniques are used to study their physical and spectral properties.

Observing the mechanisms behind the formation, evolution and interaction of giant planets remains difficult, but understanding them is vital: these planets represent the largest mass within the planetary systems they shape. They also play a key role in the dynamics of smaller, telluric planets like Earth. Future SPHERE observations will be decisive in efforts to better understand the formation and evolution of extrasolar systems. The planetary system group at LAM is in good position to continue this research and image new worlds.

About the large SHINE survey

In the framework of the SHINE (SpHere INfrared survey for Exoplanets) observation campaign. The SPHERE consortium is composed of 12 major European institutes, which designed and built the SPHERE exoplanet imager for the Very Large Telescope of the ESO. Institut de Planétologie et d’Astrophysique de Grenoble; Max-Planck-Institut für Astronomie in Heidelberg; Laboratoire d’Astrophysique de Marseille; Laboratoire d’Etudes Spatiales et d’Instrumentation en Astrophysique de l’Observatoire de Paris; Laboratoire Lagrange in Nice; ONERA; Observatoire de Genève; Italian National Institute for Astrophysics coordinated by the Osservatorio Astronomico di Padova; Institute for Astronomy, ETH Zurich; Astronomical Institute of the University of Amsterdam; Netherlands Research School for Astronomy (NOVA-ASTRON) and ESO.

About the contributions of Laboratoire d’Astrophysique de Marseille in SPHERE

In SPHERE, the Laboratoire d’Astrophysique de Marseille (LAM – http://www.lam.fr/) has been responsible of the system engineering of the complete SPHERE system and of the design of IRDIS. It is now one of the leading institutes in the SHINE survey.

In the instrument, the LAM has developed IRDIS (the main camera of SPHERE for differential imaging of exoplanets), torric mirrors of extreme quality for the main optical path and the readout electronics of the ultra-fast detectors for the adaptive optics system. LAM has also closely collaborated with ONERA, the institute responsible for the SPHERE extreme adaptive optics system.

LAM is now one of the main contributors in the SHINE survey: it is responsible for the identification of exoplanet candidates in the data and for the characterization of the new detected companions. In collaboration with the CeSAM group, LAM is developing database tools to manage the results of the SHINE survey and their scientific exploitation.

For more informations
Reference

Discovery of a warm, dusty giant planet around HIP 65426; Astronomy & Astrophysics; Chauvin, Desidera, Lagrange, Vigan et et a.; in press.
https://arxiv.org/abs/1707.01413

Contact

CNRS researcher l Arthur Vigan l 04 95 04 41 65 l arthur.vigan@lam.fr


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