A second planet in the Beta Pictoris system

© P Rubini / AM Lagrange




A team of astronomers led by Anne-Marie Lagrange, a CNRS researcher at the Institut de planétologie et d’astrophysique de Grenoble (OSUG - CNRS/Université Grenoble Alpes) [1], has discovered a second giant planet in orbit around b Pictoris, a star that is relatively young (23 million years old) and close (63.4 light years), and surrounded by a disk of dust.






The β Pictoris system has fascinated astronomers for the last thirty years since it enables them to observe a planetary system in the process of forming around its star. Comets have been discovered in the system, as well as a gas giant, β Pictoris b, detected by direct imaging and described in 2009 by Lagrange’s team. This time, the team had to analyse more than 10 years of high-resolution data, obtained with the HARPS instrument at ESO’s La Silla Observatory in Chile, in order to indirectly detect the presence of β Pictoris c [2]. This second giant planet, which has a mass nine times that of Jupiter, completes its orbit in roughly 1,200 days, and is relatively close to its star (approximately the distance between the Sun and the asteroid belt, whereas β Pictoris b is 3.3 times more distant). The researchers hope to find out more about the planet from data from the GAIA spacecraft and from the future Extremely Large Telescope now under construction in Chile.

Disque de poussières entourant β Pictoris et position des planètes β Pictoris b et c.
© P Rubini / AM Lagrange

Vue d’artiste du système β Pictoris. Au moins deux planètes géantes, âgées de 20 millions d’années tout au plus, orbitent autour de l’étoile (non visible) : β Pictoris c, la plus proche, qui vient d’être découverte, et β Pictoris b, plus éloignée. Le disque de poussières et de gaz est visible à l’arrière-plan.
© P Rubini / AM Lagrange

► This press release has originally been published by the CNRS.

Reference

Evidence for an additional planet in the β Pictoris system, Anne-Marie Lagrange, Nadège Meunier, Pascal Rubini, Miriam Keppler, Franck Galland, Eric Chapellier, Eric Michel, Luis Balona, Hervé Beust, Tristan Guillot, Antoine Grandjean, Simon Borgniet, Djamel Mekarnia, Paul Anthony Wilson, Flavien Kiefer, Mickael Bonnefoy, Jorge Lillo-Box, Blake Pantoja, Matias Jones Daniela Paz Iglesias, Laetitia Rodet, Matias Diaz, Abner Zapata, Lyu Abe, François-Xavier Schmider. Nature Astronomy 19 août 2019
DOI : 10.1038/s41550-019-0857-1

Scientific contact

 Anne-Marie Lagrange I IPAG I anne-marie.lagrange [at] univ-grenoble-alpes.fr I +0033 476514203

Published on August 19, 2019.

[1The team includes researchers from other French laboratories – Lagrange laboratory (CNRS/Observatoire de la Côte d’Azur/Université Côte d’Azur), Laboratoire d’études spatiales et d’instrumentation en astrophysique (CNRS/Observatoire de Paris – PSL/Sorbonne Université/Université de Paris), Institut d’astrophysique de Paris (CNRS/Sorbonne Université) – as well as researchers from the Max Planck Institute for Astronomy (Germany), the South African Astronomical Observatory, the University of Warwick (UK), Leiden Observatory (the Netherlands), European Southern Observatory, Universidad de Chile and Universidad de Valparaiso (Chile).

[2The method used was the radial velocity method: planets and stars orbit around a common centre of gravity which is usually located within the star. Thus, in the presence of a planet, the star describes orbits that are very small but nonetheless detectable by the radial velocity method, which is based on the Doppler effect (its light spectrum shifts alternately towards blue and red). Since β Pictoris is a relatively massive star (almost twice the mass of the Sun) that undergoes considerable pulsations (its size varies periodically), the signal obtained is extremely complicated, and it was first necessary to subtract the effect of the pulsations. In fact, this is the first time that a planet has been detected around such a star using this method.