Planetary companions around the metal-poor star HIP 11952
Abstract
Aims: We carried out a radial-velocity survey to search for planets around metal-poor stars. In this paper we report the discovery of two planets around HIP 11952, a metal-poor star with [Fe/H] = -1.9 that belongs to our target sample.
Methods: Radial velocity variations of HIP 11952 were monitored systematically with FEROS at the 2.2 m telescope located at the ESO La Silla observatory from August 2009 until January 2011. We used a cross-correlation technique to measure the stellar radial velocities (RV).
Results: We detected a long-period RV variation of 290 d and a short-period one of 6.95 d. The spectroscopic analysis of the stellar activity reveals a stellar rotation period of 4.8 d. The Hipparcos photometry data shows intra-day variabilities, which give evidence for stellar pulsations. Based on our analysis, the observed RV variations are most likely caused by the presence of unseen planetary companions. Assuming a primary mass of 0.83 M⊙, we computed minimum planetary masses of 0.78 MJup for the inner and 2.93 MJup for the outer planet. The semi-major axes are a1 = 0.07 AU and a2 = 0.81 AU, respectively.
Conclusions: HIP 11952 is one of very few stars with [Fe/H] < -1.0 which have planetary companions. This discovery is important to understand planet formation around metal-poor stars.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- April 2012
- DOI:
- 10.1051/0004-6361/201117826
- arXiv:
- arXiv:1208.4000
- Bibcode:
- 2012A&A...540A.141S
- Keywords:
-
- stars: abundances;
- techniques: spectroscopic;
- planetary systems;
- techniques: radial velocities;
- stars: individual: HIP 11952;
- Astrophysics - Earth and Planetary Astrophysics;
- Astrophysics - Solar and Stellar Astrophysics
- E-Print:
- Published in A&