TY - JOUR
T1 - Precise radial velocities of giant stars
T2 - XIII. A second Jupiter orbiting in 4:3 resonance in the 7 CMa system
AU - Luque, R.
AU - Trifonov, T.
AU - Reffert, S.
AU - Quirrenbach, A.
AU - Lee, M. H.
AU - Albrecht, S.
AU - Andersen, M. Fredslund
AU - Antoci, V.
AU - Grundahl, F.
AU - Schwab, C.
AU - Wolthoff, null
PY - 2019/11/6
Y1 - 2019/11/6
N2 - 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.
AB - 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.
KW - techniques: radial velocities
KW - planetary systems
KW - planets and satellites: dynamical evolution and stability
KW - planets and satellites: detection
U2 - 10.1051/0004-6361/201936464
DO - 10.1051/0004-6361/201936464
M3 - Article
VL - 631
SP - 1
EP - 8
JO - Astronomy and Astrophysics
JF - Astronomy and Astrophysics
SN - 0004-6361
M1 - A136
ER -