Up to seven planets orbiting HD 10180
1er août 2010
Using ESO’s world-leading HARPS instrument, a European team including an astronomer from Paris Observatory has discovered a planetary system containing at least five planets, orbiting the Sun-like star HD 10180. The researchers also have evidence of two other planets, one of which would have a terrestrial mass. This would make the system similar to our Solar System. Furthermore, the team found evidence that the location of the planets follows a regular pattern, as also seen in our Solar System. Using numerical simulations, the researchers have shown that this 7-planets system is stable if general relativity is properly taken into account.
This system is probably the most populated extrasolar planetary system known to date. "We are now entering a new era in exoplanet research : the study of complex planetary systems and not just of individual planets. Studies of planetary motions in the new system reveal complex gravitational interactions between the planets and give us insights into the long-term evolution of the system" says Christophe Lovis, from Geneva observatory, lead author of the paper reporting the result. The team of astronomers used the HARPS spectrograph, attached to ESO’s 3.6-metre telescope at La Silla, Chile, for a six-year-long study of the Sun-like star HD 10180, located 127 light-years away in the southern constellation of Hydrus. Thanks to the 190 individual HARPS measurements, the astronomers detected the wobbles of the star caused by the planets.
- Figure 1 : Vue d’artiste du système planétaire HD10180. Crédit ESO/L. Calçada Cliquer sur l’image pour l’agrandir
The conclusions are presented today (August 24) at the international conference on "Detection and dynamics of transiting exoplanets", at the Observatoire de Haute-Provence, France. The collected data showed that the star HD10180 has five Neptune-like planets, with masses between 13 and 25 times Earth’s mass and with orbital periods between 6 and 600 days. It was further found evidence for the presence of two more planets. The first one is similar to Saturn and has a mass 65 times Earth’s mass and period of 2200 days. The other will be the lowest mass planet yet found, with only 1.4 times the mass of Earth and orbiting its central star HD10180 at a distance of 3.3 million kilometers in just 28.3 hours. The newly discovered system of planets around HD 10180 is unique in several respects. First of all, with at least five Neptune-like planets lying within a distance equivalent to the orbit of Mars, this system is more populated than our Solar System in its inner region, and has many more massive planets there. Furthermore, the system probably has no Jupiter-like gas giant. So far, astronomers know of fifteen systems with at least three planets. The last record holder was 55 Cancri, which contains five planets, two of them being giant planets. Using the new discovery as well as data for other planetary systems, the astronomers discovered an equivalent of the "Titius-Bode" law that exists in our Solar System : the location of the planets seems to follow a regular pattern.
- Figure 2 : Dans un modèle purement Newtonien, l’excentricité de la planète intérieure augmente à des valeurs très élevées (en rouge) donnant lieu à des instabilités, tandis qu’elle reste faible si la relativité générale est prise en compte (en vert). Crédit : J. Laskar Cliquer sur l’image pour l’agrandir
Figure 2 : In a purely Newtonian model, the eccentricity of the inner planet grows to very high values (red) giving rise to instabilities, while it remains small when general relativity is taken into account (green). Credit : J. Laskar Click on the image to enlarge it The team is composed of C. Lovis, D. Ségransan, M. Mayor, S. Udry, F. Pepe, and D. Queloz (Observatoire de Genève, Université de Genève, Switzerland), W. Benz (Universität Bern, Switzerland), F. Bouchy (Institut d’Astrophysique de Paris, France), C. Mordasini (Max-Planck-Institut für Astronomie, Heidelberg, Germany), N. C. Santos (Universidade do Porto, Portugal), J. Laskar (Observatoire de Paris, France), A. Correia (Universidade de Aveiro, Portugal), and J.-L. Bertaux (Université Versailles Saint-Quentin, France) and G. Lo Curto (ESO). ESO press release The HARPS search for southern extra-solar planets. XXV. Up to seven planets orbiting HD 10180 : probing the architecture of low-mass planetary systems C. Lovis, D. Ségransan, M. Mayor, S. Udry, W. Benz, J.-L. Bertaux, F. Bouchy, A. C. M. Correia, J. Laskar, G. Lo Curto, C. Mordasini, F. Pepe, D. Queloz, and N. C. Santos submitted. Contact Jacques Laskar (Observatoire de Paris, IMCCE, and CNRS)
Dernière modification le 4 mars 2013