Generalized Peas in a Pod: Extending Intra-system Mass Uniformity to Non-TTV Systems via the Gini Index

Goyal, Armaan V.; Wang, Songhu

doi:10.3847/1538-4357/ac7562

Cited by 11 publications

(14 citation statements)

References 27 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The occurrence rate of these giant planets increases as a function of the amount of solid material in the disk (which is itself correlated to the mass and metallicity of the host star, Fischer & Valenti 2005, as well as the formation location within the protoplanetary disk; Wittenmyer et al 2020;Fulton et al 2021). This starting point is, in part, motivated by the prevalence of "peas-in-a-pod" chains of super-Earths and sub-Neptunes discovered in the Kepler data set (Millholland et al 2017;Weiss et al 2018;Goyal & Wang 2022), as well as the existence of Jovian planets observed in some compact multiplanet systems (see Wang et al 2017;Adams et al 2020, and Figure 1 of Dawson et al 2019). More importantly, however, we find that a framework based on this initialization is able to qualitatively reproduce the observed properties of hot and warm Jupiters, as is further discussed in Section 7.4.…”

Section: Framework Overviewmentioning

confidence: 99%

Section: Framework Overviewmentioning

confidence: 99%

See 1 more Smart Citation

Evidence for Hidden Nearby Companions to Hot Jupiters

Rice

Wang

2023

Self Cite

View full text Add to dashboard Cite

The first discovered extrasolar worlds—giant, “hot Jupiter” planets on short-period orbits—came as a surprise to solar system–centric models of planet formation, prompting the development of new theories for planetary system evolution. The near absence of observed nearby planetary companions to hot Jupiters has been widely quoted as evidence in support of high-eccentricity tidal migration, a framework in which hot Jupiters form further out in their natal protoplanetary disks before being thrown inward with extremely high eccentricities, stripping systems of any close-in planetary companions. In this work, we present new results from a search for transit timing variations across the full 4 yr Kepler data set, demonstrating that at least 12% ± 6% of hot Jupiters have a nearby planetary companion. This subset of hot Jupiters is expected to have a quiescent dynamical history such that the systems could retain their nearby companions. We also demonstrate a ubiquity of nearby planetary companions to warm Jupiters (≥70% ± 16%), indicating that warm Jupiters typically form quiescently. We conclude by combining our results with existing observational constraints to propose an “eccentric migration” framework for the formation of short-period giant planets through postdisk dynamical sculpting in compact multiplanet systems. Our framework suggests that hot Jupiters constitute the natural end stage for giant planets spanning a wide range of eccentricities, with orbits that reach small enough periapses—either from their final orbital configurations in the disk phase or from eccentricity excitation in the postdisk phase—to trigger efficient tidal circularization.

show abstract

Section: Framework Overviewmentioning

confidence: 99%

Section: Framework Overviewmentioning

confidence: 99%

Evidence for Hidden Nearby Companions to Hot Jupiters

Rice

Wang

2023

Self Cite

View full text Add to dashboard Cite

show abstract

“…Previous studies of multiplanet systems have revealed that planets within the same system tend to have similar radii, orbital spacings (Weiss et al 2018b), and masses (Millholland et al 2017;Goyal & Wang 2022), such that they are like "peas in a pod". Put another way, planets within the same system have similar bulk densities.…”

Section: Planetary Core/water Mass Fractionsmentioning

confidence: 99%

A Comparison of the Composition of Planets in Single-planet and Multiplanet Systems Orbiting M dwarfs

Rodríguez Martínez,

Martin,

Gaudi

et al. 2023

View full text Add to dashboard Cite

We investigate and compare the composition of M-dwarf planets in systems with only one known planet (“singles”) to those residing in multiplanet systems (“multis”) and the fundamental properties of their host stars. We restrict our analysis to planets with directly measured masses and radii, which comprise a total of 70 planets: 30 singles and 40 multis in 19 systems. We compare the bulk densities for the full sample, which includes planets ranging in size from 0.52 R ⊕ to 12.8 R ⊕, and find that single planets have significantly lower densities on average than multis, which we cannot attribute to selection biases. We compare the bulk densities normalized by an Earth model for planets with R p < 6 R ⊕ and find that multis are also denser with 99% confidence. We calculate and compare the core/water mass fractions (CMF/WMF) of low-mass planets (M p < 10 M ⊕) and find that the likely rocky multis (with R p < 1.6 R ⊕) have lower CMFs than singles. We also compare the [Fe/H] metallicity and rotation period of all single-planet versus multiplanet host stars with such measurements in the literature and find that multiplanet hosts are significantly more metal-poor than those hosting a single planet. Moreover, we find that the host star metallicity decreases with increasing planet multiplicity. In contrast, we find only a modest difference in the rotation period. The significant differences in planetary composition and metallicity of the host stars point to different physical processes governing the formation of single-planet and multiplanet systems in M dwarfs.

show abstract

“…Following the methodology of Goyal & Wang (2022), we adopt the adjusted Gini index (Gini 1912;Deltas 2003), a statistic commonly used in economics to quantify income or wealth inequality in a given population, as our primary metric for the assessment of intra-system size uniformity across our sample. For a given data vector x with size N, the standard Gini index can be calculated as follows:…”

Section: Gini Indexmentioning

confidence: 99%

“…The extension of peas-in-a-pod uniformity to planetary mass, however, necessitates consideration of orbital resonances due to the distinct observational means (Lithwick & Wu 2012) by which mass measurements may be obtained for systems near or distant from mean motion resonance (MMR): individual transiting planets in a nonresonant system may have their masses constrained by radial velocity (RV) follow-up (Batalha et al 2011;Weiss & Marcy 2014), while planet pairs whose orbits lie near MMR may have their masses determined instead via analysis of their transit timing variations (TTVs; Lithwick & Wu 2012;Steffen et al 2012;Xie 2013;Hadden & Lithwick 2017). Nonetheless, intra-system mass uniformity has been demonstrated independently for near-resonant systems exhibiting strong TTVs (Millholland et al 2017), predominantly nonresonant systems with RV masses (Goyal & Wang 2022), a mixed sample of both system types (Wang 2017;Otegi et al 2022), thereby suggesting that the emergence of peas-in-a-pod regularity persists regardless of proximity to MMR.…”

Section: Introductionmentioning

confidence: 99%

Enhanced Size Uniformity for Near-resonant Planets

Goyal,

Dai,

Wang

2023

ApJ

Self Cite

View full text Add to dashboard Cite

Super-Earths within the same close-in, compact planetary system tend to exhibit a striking degree of uniformity in their radius, mass, and orbital spacing, and this “peas-in-a-pod” phenomenon itself serves to provide one of the strongest constrains on planet formation at large. While it has been recently demonstrated from independent samples that such planetary uniformity occurs for both configurations near and distant from mean motion resonance, the question thus remains if the strength of this uniformity itself differs between near-resonant and nonresonant configurations such that the two modes may be astrophysically distinct in their evolution. We thus provide in this work a novel comparative size uniformity analysis for 48 near-resonant and 251 nonresonant multiplanet systems from the California Kepler Survey catalog, evaluating uniformity both across systems and between planetary pairs within the same system. We find that while multiplanet configurations exhibit strong peas-in-a-pod size uniformity regardless of their proximity to resonance, near-resonant configurations display enhanced intra-system size uniformity as compared to their analogous nonresonant counterparts at the level of both entire systems and subsystem planetary pairs and chains. These results are broadly consistent with a variety of formation paradigms for multiple-planet systems, such as convergent migration within a turbulent protoplanetary disk or planet–planet interactions incited by postnebular dynamical instabilities. Nevertheless, further investigation is necessary to ascertain whether the nonresonant and near-resonant planetary configurations respectively evolve via a singular process or mechanisms that are dynamically distinct.

show abstract

Generalized Peas in a Pod: Extending Intra-system Mass Uniformity to Non-TTV Systems via the Gini Index

Cited by 11 publications

References 27 publications

Evidence for Hidden Nearby Companions to Hot Jupiters

Evidence for Hidden Nearby Companions to Hot Jupiters

A Comparison of the Composition of Planets in Single-planet and Multiplanet Systems Orbiting M dwarfs

Enhanced Size Uniformity for Near-resonant Planets

Contact Info

Product

Resources

About