Two Jovian planets around the giant star HD202696. A growing population of packed massive planetary pairs around massive stars?

Abstract

We present evidence for a new two-planet system around the giant star HD202696 (= HIP105056, BD+26 4118). The discovery is based on public HIRES radial velocity measurements taken at Keck Observatory between July 2007 and September 2014. We estimate a stellar mass of 1.91${}_{-0.14}^{+0.09}{M}_{\odot }$ for HD202696, which is located close to the base of the red giant branch. A two-planet self-consistent dynamical modeling MCMC scheme of the radial velocity data followed by a long-term stability test suggests planetary orbital periods of $P_{\mathrm{b}}$ = 517.8${}_{-3.9}^{+8.9}$ days and $P_{\mathrm{c}}$ = 946.6${}_{-20.9}^{+20.7}$ days, eccentricities of $e_{\mathrm{b}}$ = 0.011${}_{-0.011}^{+0.078}$ and $e_{\mathrm{c}}$ = 0.028${}_{-0.012}^{+0.065}$ , and minimum dynamical masses of $m_{\mathrm{b}}$ = 2.00${}_{-0.10}^{+0.22}$\,$M_{\mathrm{Jup}}$ and $m_{\mathrm{c}}$ = 1.86${}_{-0.23}^{+0.18}$,$M_{\mathrm{Jup}}$, respectively. Our stable MCMC samples are consistent with orbital configurations predominantly in a mean period ratio of 11:6 and its close-by high order mean-motion commensurabilities with low eccentricities. For the majority of the stable configurations we find an aligned or anti-aligned apsidal libration (i.e.\ $\Delta \omega$ librating around 0${}^{\circ }$ or 180${}^{\circ }$), suggesting that the HD202696 system is likely dominated by secular perturbations near the high-order 11:6 mean-motion resonance. The HD202696 system is yet another Jovian mass pair around an intermediate mass star with a period ratio below the 2:1 mean motion resonance. Therefore, the HD202696 system is an important discovery, which may shed light on the primordial disk-planet properties needed for giant planets to break the strong 2:1 mean motion resonance and settle in more compact orbits.

arXiv commentAccepted for publication in AJ on 18th December 2018. 15 pages, 11 Figures, 4 Tables (this .v2 is copy corrected and identical with the published paper)

References in corpus (41)

• emcee: The MCMC Hammer
• Gaia Data Release 2. Summary of the contents and survey properties
• The Gaia mission
• PARSEC: stellar tracks and isochrones with the PAdova and TRieste Stellar Evolution Code
• Estimating distances from parallaxes IV: Distances to 1.33 billion stars in Gaia Data Release 2
• The generalised Lomb-Scargle periodogram. A new formalism for the floating-mean and Keplerian periodograms
• A terrestrial planet candidate in a temperate orbit around Proxima Centauri
• A low mass for Mars from Jupiter's early gas-driven migration
• Interpreting Spectral Energy Distributions from Young Stellar Objects. II. Fitting observed SEDs using a large grid of pre-computed models
• The LCES HIRES/Keck Precision Radial Velocity Exoplanet Survey
• Runaway migration and the formation of hot Jupiters
• Reversing type II migration: resonance trapping of a lighter giant protoplanet
• The Lick-Carnegie Exoplanet Survey: A Uranus-mass Fourth Planet for GJ 876 in an Extrasolar Laplace Configuration
• Gas Flow Across Gaps in Protoplanetary Disks
• CERES: A Set of Automated Routines for Echelle Spectra
• An Empirical UBVRIJHK Color-Temperature Calibration for Stars
• Overstable Librations can account for the Paucity of Mean Motion Resonances among Exoplanet Pairs
• Extrasolar Planets in Mean-Motion Resonance: Apses Alignment and Asymmetric Stationary Solutions
• Secular Evolution of Hierarchical Planetary Systems
• The radial dependence of pebble accretion rates: A source of diversity in planetary systems I. Analytical formulation
• Systemic: A Testbed For Characterizing the Detection of Extrasolar Planets. I. The Systemic Console Package
• Amplitudes of solar-like oscillations: a new scaling relation
• Accounting for velocity jitter in planet search surveys
• Retired A Stars and Their Companions VI. A Pair of Interacting Exoplanet Pairs Around the Subgiants 24 Sextanis and HD200964
• An Empirically Derived Three-Dimensional Laplace Resonance in the Gliese 876 Planetary System
• ZASPE: A Code to Measure Stellar Atmospheric Parameters and their Covariance from Spectra
• Outward migration of Jupiter and Saturn in 3:2 or 2:1 resonance in radiative disks: implications for the Grand Tack and Nice models
• Characterizing the Orbital and Dynamical State of the HD 82943 Planetary System With Keck Radial Velocity Data
• Newly-Discovered Planets Orbiting HD~5319, HD~11506, HD~75784 and HD~10442 from the N2K Consortium
• Substellar Companions to Seven Evolved Intermediate-Mass Stars
• Traditional formation scenarios fail to explain 4:3 mean motion resonances
• Resonances Required: Dynamical Analysis of the 24 Sex and HD 200964 Planetary Systems
• Precise radial velocities of giant stars. X. Bayesian stellar parameters and evolutionary stages for 372 giant stars from the Lick planet search
• Formation and evolution of the two 4/3 resonant giants planets in HD 200946
• The Pan-Pacific Planet Search. IV. Two super-Jupiters in a 3:5 resonance orbiting the giant star HD33844
• Verifying reddening and extinction for Gaia DR1 TGAS main sequence stars
• Two Jovian-Mass Planets in Earthlike Orbits
• A Pair of Giant Planets around the Evolved Intermediate-Mass Star HD 47366: Multiple Circular Orbits or a Mutually Retrograde Configuration
• Dynamical analysis of the circumprimary planet in the eccentric binary system HD59686
• On the orbital evolution of a pair of giant planets in mean motion resonance
• Re-analysing the dynamical stability of the HD 47366 planetary system

Cited by in corpus (20)

• A public HARPS radial velocity database corrected for systematic errors
• An Integrable Model for the Dynamics of Planetary Mean Motion Resonances
• A pair of warm giant planets near the 2:1 mean motion resonance around the K-dwarf star TOI-2202
• Fly-by encounters between two planetary systems II: Exploring the interactions of diverse planetary system architectures
• On the safe use of prior densities for Bayesian model selection
• Adaptive quadrature schemes for Bayesian inference via active learning
• A general stability-driven approach for the refinement of multi-planet systems
• Modeling Radial Velocity Data of Resonant Planets to Infer Migration Histories
• Speckle Imaging Characterization of Radial Velocity Exoplanet Systems
• A Pair of Planets Likely in Mean-motion Resonance From Gravitational Microlensing
• A Bayesian inference and model selection algorithm with an optimisation scheme to infer the model noise power
• Measuring the Orbital Parameters of Radial Velocity Systems in Mean Motion Resonance---a Case Study of HD 200964
• A Trio of Giant Planets Orbiting Evolved Star HD 184010
• Precise radial velocities of giant stars XIII. A second Jupiter orbiting in 4:3 resonance in the 7 CMa system
• Deep Importance Sampling based on Regression for Model Inversion and Emulation
• A new third planet and the dynamical architecture of the HD33142 planetary system
• Dynamical architecture of the HD 107148 system
• Compressed particle methods for expensive models with application in Astronomy and Remote Sensing
• Automatic tempered posterior distributions for Bayesian inversion problems
• Influence of Modeling Assumptions on the Inferred Dynamical State of Resonant Systems: A Case Study of the HD 45364 System