Framework for the architecture of exoplanetary systems

Abstract

We present a novel, model-independent framework for studying the architecture of an exoplanetary system at the system level. This framework allows us to characterise, quantify, and classify the architecture of an individual planetary system. Our aim in this endeavour is to generate a systematic method to study the arrangement and distribution of various planetary quantities within a single planetary system. We propose that the space of planetary system architectures be partitioned into four classes: similar, mixed, anti-ordered, and ordered. We applied our framework to observed and synthetic multi-planetary systems, thereby studying their architectures of mass, radius, density, core mass, and the core water mass fraction. We explored the relationships between a system’s (mass) architecture and other properties. Our work suggests that: (a) similar architectures are the most common outcome of planet formation; (b) internal structure and composition of planets shows a strong link with their system architecture; (c) most systems inherit their mass architecture from their core mass architecture; (d) most planets that started inside the ice line and formed in-situ are found in systems with a similar architecture; and (e) most anti-ordered systems are expected to be rich in wet planets, while most observed mass ordered systems are expected to have many dry planets. We find, in good agreement with theory, that observations are generally biased towards the discovery of systems whose density architectures are similar, mixed, or anti-ordered. This study probes novel questions and new parameter spaces for understanding theory and observations. Future studies may utilise our framework to not only constrain the knowledge of individual planets, but also the multi-faceted architecture of an entire planetary system. We also speculate on the role of system architectures in hosting habitable worlds.

Earths Are Not Super-Earths, Saturns Are Not Jupiters: Imprints of Pressure-bump Planet Formation on Planetary Architectures

“…The existence of intra-system similar Jupiter pairs and the diverse architecture that can be produced by their instability does not seem to be recovered by existing population syntheses (which do not include the effect of pressure bumps). For example, in Mishra et al (2023), it seems uncommon for synthesized systems (their Figure 6, right panel) to have giant planets in very similar masses (mass ratio 0.8, corresponding to the peak in Figure 4). Their synthesized systems also do not show any significant mass inversion (large-small-large configuration, as opposed to the more typical monotonic or smalllarge-small configuration), which has been observed in a few systems and might be explained by the instability of Jupiter pairs.…”

“…This diagram is for illustration only, and the samples shown here may not be statistically representative of the whole planet population. All systems are chosen from a catalog of known systems with four planets compiled inMishra et al (2023), with the exception of HD 37124, which serves as an example of a Jupiter triplet. Generally, a system can contain multiple classes of planets; we highlight the planets that belong to the relevant class with filled markers, and other planets are indicated by open markers.…”

Planetary Engulfment Prognosis within the ρ CrB System

“…From the plethora of exoplanet discoveries, a vast array of system architectures have been revealed, many of which differ significantly from the solar system (Ford 2014;Winn & Fabrycky 2015;Horner et al 2020;Kane et al 2021;Mishra et al 2023aMishra et al , 2023b. The majority of these exoplanet discoveries have occurred through the use of the transit or radial velocity (RV) methods.…”

Surrounded by Giants: Habitable Zone Stability Within the HD 141399 System

“…The origin and evolution of planetary architectures are key areas of study within exoplanetary science. The large number of discovered planets allows a statistical analysis of these architectures and a direct comparison with the solar system (Ford 2014;Winn & Fabrycky 2015;Horner et al 2020;Kane et al 2021a;Mishra et al 2023aMishra et al , 2023b. In particular, we are beginning to understand the prevalence of Jupiter analogs (Wittenmyer et al 2011(Wittenmyer et al , 2020Fulton et al 2021;Rosenthal et al 2021), largely from the long baseline of radial velocity (RV) observations (Kane et al 2007;Ford 2008;Wittenmyer et al 2013).…”