Precise radial velocities of giant stars

• Verfasst von: Luque, Rafael [VerfasserIn]
• Verfasst von: Reffert, Sabine [VerfasserIn]
• Verfasst von: Quirrenbach, Andreas [VerfasserIn]
• Verfasst von: Wolthoff, Vera [VerfasserIn]
• Titel: Precise radial velocities of giant stars
• Titelzusatz: XIII. A second Jupiter orbiting in 4:3 resonance in the 7 CMa system
• Verf.angabe: R. Luque, T. Trifonov, S. Reffert, A. Quirrenbach, M.H. Lee, S. Albrecht, M. Fredslund Andersen, V. Antoci, F. Grundahl, C. Schwab, and V. Wolthoff
• E-Jahr: 2019
• Jahr: 06 November 2019
• Umfang: 8 S.
• Fussnoten: Gesehen am 12.02.2020
• Titel Quelle: Enthalten in: Astronomy and astrophysics
• Ort Quelle: Les Ulis : EDP Sciences, 1969
• Jahr Quelle: 2019
• Band/Heft Quelle: 631(2019) Artikel-Nummer A136, 8 Seiten
• ISSN Quelle: 1432-0746
• DOI: doi:10.1051/0004-6361/201936464
• Datenträger: Online-Ressource
• Sprache: eng
• K10plus-PPN: 168988116X

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 sin i ~ 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.