SARG@TNG data contribute to the discovery of the youngest candidate exoplanet ever observed

In the last 15 years more than 400 exoplanets (planets orbiting around stars other than the Sun and thus beyond the Solar System) have been discovered. They span a wide range of masses, distances from their parent star and orbital properties and pose one of the most important problems of modern astrophysics. In fact, despite of the large amount of data collected so far, the mechanisms involved in the formation and evolution of planets are poorly understood. In particular, their "childhood" is a complete mistery.

Recently, a new discovery could shed new light on the first stages of planet evolution. In fact, a team of Spanish researchers has reported the detection of a very young candidate planet. It has been found by analyzing high-resolution echelle spectra of BD+20 1790, a young, active, metal rich, K5V star located in the constellation of Gemini. The instrument SARG of the Telescopio Nazionale Galileo has played an important role in this investigation.

The new candidate exoplanet (named BD+20 1790b) has been detected by observing periodic variations of the radial velocity of the parent star. It is a giant gaseous planet, with a mass 6 times larger than the mass of Jupiter, orbiting very close to its star (at a distance of about 0.07 AU, much smaller than the distance Sun-Mercury) with a period of only 7.78 days.

The importance of the discovery of BD+20 1790b resides in its very young age. In fact, with its 35 Myrs estimated age it is by far the youngest candidate exoplanet discovered around a main-sequence star. Its detection fills an hole in the range of exoplanets ages and could help astrophysicists to understand how planets form from the disks of dust and debris surrounding young stars.

Couriously, the radial velocity data of BD+20 1790 collected with SARG@TNG are not part of a exoplanet search program. Therefore, the discovery of BD+20 1790b is a serendipitous finding.

(M. Hernan-Obispo et al., "Evidence of a massive planet candidate orbiting the young active K5V star BD+20 1790", 2010, Astronomy and Astrophysics, in press (astro-ph 0912.2773v1))

Fig.1: Artist's impression of the planet around the star BD+20 1790. (Credit: El Mundo.es and M. Hernan-Obispo).