The Impact of Stellar Clustering on the Observed Multiplicity of Super-Earth systems: Outside-in Cascade of Orbital Misalignments Initiated by Stellar Flybys
arXiv:2107.06412 · doi:10.1093/mnras/stab3046
Abstract
A recent study suggests that the observed multiplicity of super-Earth (SE) systems is correlated with stellar overdensities: field stars in high phase-space density environments have an excess of single-planet systems compared to stars in low density fields. This correlation is puzzling as stellar clustering is expected to influence mostly the outer part of planetary systems. Here we examine the possibility that stellar flybys indirectly excite the mutual inclinations of initially coplanar SEs, breaking their co-transiting geometry. We propose that flybys excite the inclinations of exterior substellar companions, which then propagate the perturbation to the inner SEs. Using analytical calculations of the secular coupling between SEs and companions, together with numerical simulations of stellar encounters, we estimate the expected number of "effective" flybys per planetary system that lead to the destruction of the SE co-transiting geometry. Our analytical results can be rescaled easily for various SE and companion properties (masses and semi-major axes) and stellar cluster parameters (density, velocity dispersion and lifetime). We show that for a given SE system, there exists an optimal companion architecture that leads to the maximum number of effective flybys; this results from the trade-off between the flyby cross section and the companion's impact on the inner system. Subject to uncertainties in the cluster parameters, we conclude that this mechanism is inefficient if the SE system has a single exterior companion, but may play an important role in "SE + two companions" systems that were born in dense stellar clusters. Whether this effect causes the observed correlation between planet multiplicity and stellar overdensities remains to be confirmed.
arXiv comment16 pages, 18 figures, accepted in MNRAS
References in corpus (39)
- SciPy 1.0--Fundamental Algorithms for Scientific Computing in Python
- Array Programming with NumPy
- Gaia Data Release 2. Summary of the contents and survey properties
- The Occurrence and Architecture of Exoplanetary Systems
- Architecture and Dynamics of Kepler's Candidate Multiple Transiting Planet Systems
- Architecture of Kepler's Multi-transiting Systems: II. New investigations with twice as many candidates
- About 30% of Sun-like Stars Have Kepler-like Planetary Systems: A Study of their Intrinsic Architecture
- The effects of fly-bys on planetary systems
- An Excess of Jupiter Analogs in Super-Earth Systems
- The Super Earth-Cold Jupiter Relations
- Black Hole and Neutron Star Binary Mergers in Triple Systems: Merger Fraction and Spin-Orbit Misalignment
- Architectures of Exoplanetary Systems. I: A Clustered Forward Model for Exoplanetary Systems around Kepler's FGK Stars
- Can planetary instability explain the Kepler dichotomy?
- Excitation and Propagation of Eccentricity Disturbances in Planetary Systems
- The effects of dynamical interactions on planets in young substructured star clusters
- Stability of Multiplanetary Systems in Star Clusters
- Orbit alignment in triple stars
- The effects of external planets on inner systems: multiplicities, inclinations, and pathways to eccentric warm Jupiters
- Stellar clustering shapes the architectures of planetary systems
- Hiding Planets Behind a Big Friend: Mutual Inclinations of Multi-Planet Systems with External Companions
- Obliquity Constraints on an Extrasolar Planetary-Mass Companion
- Compact planetary systems perturbed by an inclined companion: II. Stellar spin-orbit evolution
- Effects of Unseen Additional Planetary Perturbers on Compact Extrasolar Planetary Systems
- Eccentricities and Inclinations of Multi-Planet Systems with External Perturbers
- Dynamically hot Super-Earths from outer giant planet scattering
- Perturbation of Compact Planetary Systems by Distant Giant Planets
- Hidden Planetary Friends: On the Stability Of 2-Planet Systems in the Presence of a Distant, Inclined Companion
- Survival of habitable planets in unstable planetary systems
- On the Correlation between Hot Jupiters and Stellar Clustering: High-eccentricity Migration Induced by Stellar Flybys
- Fly-by encounters between two planetary systems II: Exploring the interactions of diverse planetary system architectures
- Strong Scatterings of Cold Jupiters and their Influence on Inner Low-mass Planet Systems: Theory and Simulations
- On the stellar clustering and architecture of planetary systems
- Hot Jupiter and ultra-cold Saturn formation in dense star clusters
- Encounters involving planetary systems in birth environments: the significant role of binaries
- Transit Probabilities in Secularly Evolving Planetary Systems
- The Impact of Stellar Clustering on the Observed Multiplicity and Orbital Periods of Planetary Systems
- Inclination Dynamics of Resonant Planets under the Influence of an Inclined External Companion
- Not the Birth Cluster: the Stellar Clustering that Shapes Planetary Systems is Generated by Galactic-Dynamical Perturbations
- Evidence for a Non-Dichotomous Solution to the Kepler Dichotomy: Mutual Inclinations of Kepler Planetary Systems from Transit Duration Variations