Aims: Even with three planets in the system, the data points keep anomalously high dispersion around the fitted solution. The high residuals are only partially due to the strong p-mode oscillations of the host star. We therefore studied the possible presence of a fourth planet in this system.
Methods: During the past years we carried out additional and extremely precise radial-velocity measurements with the HARPS spectrograph. These data turned out to be highly important for constraining the many free parameters in a four-planet orbital fit. Nevertheless, the search for the best solution remains difficult in this complex and multi-dimensional parameter space. The new Stakanof software, that uses an optimized genetic algorithm, helped us considerably in this task and made our search extremely efficient and successful.
Results: We provide a full orbital solution of the planetary system around μ Arae. It turns out to be the second system known to harbor 4 planetary companions. Before this study,
Astronomy and Astrophysics
- Pub Date:
- February 2007
- instrumentation: spectrographs;
- techniques: radial velocities;
- stars: individual: <ASTROBJ>μ Arae</ASTROBJ> (HD 160691);
- stars: planetary systems;
- 11 pages, 8 low-resolution figures. Submitted to A&