ARCHITECTURE OF PLANETARY SYSTEMS BASED ON KEPLER DATA: NUMBER OF PLANETS AND COPLANARITY

By Julia Fang, Jean-Luc Margot. 2012

167 citations recorded by the source corpus.

We investigated the underlying architecture of planetary systems by deriving the distribution of planet multiplicity (number of planets) and the distribution of orbital inclinations based on the sample of planet candidates discovered by the Kepler mission. The scope of our study included solar-like stars and planets with orbital periods less than 200 days and with radii between 1.5 and 30 Earth radii, and was based on Kepler planet candidates detected during Quarters 1–6. We created models of planetary systems with different distributions of planet multiplicity and inclinations, simulated observations of these systems by Kepler, and compared the properties of the transits of detectable objects to actual Kepler planet detections. Specifically, we compared with both the Kepler sample's transit numbers and normalized transit duration ratios in order to determine each model's goodness of fit. We did not include any constraints from radial velocity surveys. Based on our best-fit models, 75%–80% of planetary systems have one or two planets with orbital periods less than 200 days. In addition, over 85% of planets have orbital inclinations less than 3° (relative to a common reference plane). This high degree of coplanarity is comparable to that seen in our solar system. These results have implications for planet formation and evolution theories. Low inclinations are consistent with planets forming in a protoplanetary disk, followed by evolution without significant and lasting perturbations from other bodies capable of increasing inclinations.

Subfields: Astronomy and Astrophysics, Instrumentation, Statistical and Nonlinear Physics

View Paper: https://www.semanticscholar.org/paper/852d9df2da63d8622d8ff2f4e62b39badf0c16f5

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In Astronomy and Astrophysics

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In Statistical and Nonlinear Physics

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Citations in the corpus

• DENSITIES AND ECCENTRICITIES OF 139 KEPLER PLANETS FROM TRANSIT TIME VARIATIONS (2013, background): “The inclination dispersion is found to be very small– a few degrees (e.g., Lissauer et al. 2011a; Figueira et al. 2012; Tremaine & Dong 2012; Fang & Margot 2012; Johansen et al. 2012; Weissbein et al. 2012).”
• About 30% of Sun-like Stars Have Kepler-like Planetary Systems: A Study of Their Intrinsic Architecture (2018, methodology): “Either using the combined constraints of Kepler and Radial Velocity (RV) data (Tremaine & Dong 2012; Figueira et al. 2012) or transit duration distributions normalized by orbital velocities (Fabrycky et al. 2014; Fang & Margot 2012), multi-tranet systems are found to be on average nearly co-planar.”
• Spacing of Kepler Planets: Sculpting by Dynamical Instability (2015, background): “Planets detected in these systems likely possess low mutual inclinations (e.g. Lissauer et al. 2011b; Tremaine & Dong 2012; Fang & Margot 2012; Fabrycky et al. 2014), and are spaced closely.”
• They are small worlds after all: revised properties of Kepler M dwarf stars and their planets (2015, background): “A full description of the occurrence of planets should include a description of their non-Poisson correlated distribution among stars (Swift et al. 2013; Muirhead et al. 2015; Ballard & Johnson 2016) and the coplanarity of their orbits (Lissauer et al. 2011; Fang & Margot 2012).”
• The Exoplanet Population Observation Simulator. I. The Inner Edges of Planetary Systems (2018, background): “Ensemble populations of systems with six or more planets with mutual inclinations of a few degrees provide a good match to the observed population of multi-planet systems (Lissauer et al. 2011; Fang & Margot 2012; Fabrycky et al. 2014; Ballard & Johnson 2016).”
• TESTING IN SITU ASSEMBLY WITH THE KEPLER PLANET CANDIDATE SAMPLE (2013, methodology): “There is also a consistency of the observed ratios despite different sample selections by different authors (Lissauer et al. 2011b; Tremaine & Dong 2012; Fang & Margot 2012), suggesting that the comparison is also robust with respect to the particular observational cuts.”
• A PLATEAU IN THE PLANET POPULATION BELOW TWICE THE SIZE OF EARTH (2013, background): “We find the in situ model plausible because it naturally explains the large number of close, sub-Neptunesize planets, the high rate of planet multiplicity and nearly co-planar and circular orbits (Lissauer et al. 2011; Fang & Margot 2012), and does not require tuning of planet migration models.”
• Close-in planetesimal formation by pile-up of drifting pebbles (2016, background): “The universality of pebble pile-ups would support the in situ formation scenario for the tightly packed exoplanetary systems detected by the Kepler mission (Fang & Margot 2012).”
• THE RADIUS DISTRIBUTION OF PLANETS AROUND COOL STARS (2013, background): “The low inferred mutual inclination of multi-transit systems (∼ 1◦– 3◦; Fabrycky et al. 2012; Fang & Margot 2012) together with the relative number of single versus multi-transit systems provides constraints on the number of planets in a given system within Kepler ’s discovery window, else it may…”
• The Occurrence and Architecture of Exoplanetary Systems (2014, methodology): “Fang & Margot (2012) combined this technique with multiplicity statistics and came to a similar conclusion.”
• The California-Kepler Survey. V. Peas in a Pod: Planets in a Kepler Multi-planet System Are Similar in Size and Regularly Spaced (2017, background): “Fang & Margot (2012), Pu & Wu (2015), and Dawson et al. (2016) have also estimated that the Kepler planets have a typical spacing of about 20 mutual Hill radii, but our updated planet radii and stellar masses allow more precise empirical estimates.”
• The Habitability of Planets Orbiting M-dwarf Stars (2016, background): “For Kepler’s multi-planet systems, flat (mutual inclinations drawn from a Rayleigh distribution with σ < 3◦) and manifold models are apt descriptors (Lissauer et al., 2011; Tremaine & Dong, 2012; Fang & Margot, 2012; Fabrycky et al., 2014; Swift et al., 2013a).”
• Breaking the chains: hot super-Earth systems from migration and disruption of compact resonant chains (2017, background): “The small contribution of near-coplanar stable systems provides large N systems whereas the broad inclination distribution of unstable systems creates a peak at low N. Fang & Margot (2012) were able to match the dichotomy by introducing an additional parameter: the multiplicity distribution.”