TNG discovers a giant planet in the triple system HD132563

An extrasolar planet in the triple stellar system has been discovered at Telescopio Nazionale Galileo (TNG). Very few planets are known in this kind of systems.

The planet orbits with a period of about 4 years at 2.6 astronomical units from the secondary of the system, HD132563B. The planet mass is about 1.5 Jupiter masses. The primary of the system, HD132563A, was found to have a close stellar companion in a highly eccentric orbit. However, the separation between HD 132563 A and B is about 400 astronomical units, 10 times the separation of Pluto from the Sun in the Solar System, leaving room for a safe orbit for the planet around HD132563B.

The discovery of planets in multiple systems is important to understand the effects of dynamical interactions on the formation and evolution and to compare the chemical abundances of the stars with and without planets, which can not be performed with similar accuracies for isolated field stars.

This discovery is entirely based on TNG data, as part of a survey started several years ago looking for planets in multiple stellar systems. It made use of the high resolution spectrograph SARG to measure the subtle variations of the velocity of the star due to the presence of the planet.

The team includes scientists from Padova and Catania observatories, Telescopio Nazionale Galileo (Canary islands), Padova University, Mc Donald Observatory (USA), Nice Observatory (F) and Toronto University (CA).

There are good perspectives for finding lower mass planets and even Earth-like planets at TNG, with the commissioning of HARPS-N, a high-resolution spectrograph optimized for extreme radial velocity precision, expected for spring 2012 (Harps-n).

S. Desidera et al., "A giant planet in the triple system HD132563", Astronomy & Astrophysics, (in press)