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- Title
Precise radial velocities of giant stars: XIII. A second Jupiter orbiting in 4:3 resonance in the 7 CMa system.
- Authors
Luque, R.; Trifonov, T.; Reffert, S.; Quirrenbach, A.; Lee, M. H.; Albrecht, S.; Fredslund Andersen, M.; Antoci, V.; Grundahl, F.; Schwab, C.; Wolthoff, V.
- Abstract
We report the discovery of a second planet orbiting the K giant star 7 CMa based on 166 high-precision radial velocities obtained with Lick, HARPS, UCLES, and SONG. The periodogram analysis reveals two periodic signals of approximately 745 and 980 d, associated with planetary companions. A double-Keplerian orbital fit of the data reveals two Jupiter-like planets with minimum masses mb sini ~ 1.9 MJ and mc sini ~ 0.9 MJ, orbiting at semimajor axes of ab ~ 1.75 au and ac ~ 2.15 au, respectively. Given the small orbital separation and the large minimum masses of the planets, close encounters may occur within the time baseline of the observations; thus, a more accurate N-body dynamical modeling of the available data is performed. The dynamical best-fit solution leads to collision of the planets and we explore the long-term stable configuration of the system in a Bayesian framework, confirming that 13% of the posterior samples are stable for at least 10 Myr. The result from the stability analysis indicates that the two planets are trapped in a low-eccentricity 4:3 mean motion resonance. This is only the third discovered system to be inside a 4:3 resonance, making this discovery very valuable for planet formation and orbital evolution models.
- Subjects
RADIAL velocity of stars; RESONANCE; PLANETARY mass; ORIGIN of planets; PLANETARY orbits; GIANT stars
- Publication
Astronomy & Astrophysics / Astronomie et Astrophysique, 2019, Vol 631, p1
- ISSN
0004-6361
- Publication type
Article
- DOI
10.1051/0004-6361/201936464