The Influence of Cold Jupiters in the Formation of Close-in Planets. I. Planetesimal Transport

Abstract

The formation of a cold Jupiter (CJ) is expected to quench the influx of pebbles and the migration of cores interior to its orbit, thus limiting the efficiency of rocky planet formation either by pebble accretion and/or orbital migration. Observations, however, show that the presence of outer CJs (>1 au and ≳0.3M Jup) correlates with the presence of inner super-Earths (at <1 au). This observation may simply be a result of an enhanced initial reservoir of solids in the nebula required to form a CJ or a yet-to-be-determined mechanism assisted by the presence of the CJ. In this work, we focus on the latter alternative and study the orbital transport of planetesimals interior to a slightly eccentric (∼0.05) CJ subject to the gravity and drag from a viscously evolving gaseous disk. We find that a secular resonance sweeping inward through the disk gradually transports rings of planetesimals when their drag-assisted orbital decay is faster than the speed of the resonance scanning. This snowplow-like process leads to large concentration (boosted by a factor of ∼10–100) of size-segregated planetesimal rings with aligned apsidal lines, making their expected collisions less destructive, due to their reduced velocity dispersion. This process is efficient for a wide range of α-disk models (and thus disk lifetimes) and Jovian masses, peaking for values ∼1–5M Jup, which are typical of observed CJs in radial velocity surveys. Overall, our work highlights the major role that the disk's gravity may have on the orbital redistribution of planetesimals, depicting a novel avenue by which CJs may enhance the formation of inner planetary systems, including super-Earths and perhaps even warm and hot Jupiters.

The Metallicity Dimension of the Super Earth-cold Jupiter Correlation

“…The current planet sample remains too small to fully establish the correlation between inner small planets and outer giant planets and explore its dependence on properties of the host stars and the planetary systems (see some early attempts by Zhu 2019 andWeiss 2023), making it difficult to test predictions of formation models (e.g., Schlecker et al 2021;Best et al 2024;Bitsch & Izidoro 2023). The ongoing RV follow-up observations of transiting systems (e.g., Bonomo et al 2023;Van Zandt et al 2023;Weiss et al 2024) and upcoming Gaia astrometric detections (e.g., Perryman et al 2014;Espinoza-Retamal et al 2023) aided by careful statistical analysis will be helpful in this regard.…”

“…The inversion of this conditional rate seems to suggest that most, if not all, of cold Jupiter systems should have inner super Earths Bryan et al 2019; but see also Barbato et al 2018 andRosenthal et al 2022 for some lower estimates). The observed strong correlation between super Earths and cold Jupiters has motivated further development of various theoretical models (e.g., Bitsch et al 2020;Chen et al 2020;Schlecker et al 2021;Best et al 2024;Bitsch & Izidoro 2023;Chachan & Lee 2023).…”

Massive Debris Disks May Hinder Secular Stirring by Planetary Companions: An Analytic Proof of Concept

“…For instance, Rafikov (2013aRafikov ( , 2013b was first to show that massive, axisymmetric protoplanetary disks can counteract perturbations due to eccentric stellar companions in S-and P-type systems. This could help in, e.g., overcoming the infamous fragmentation barrier by preventing planetesimals from being compelled into highly eccentric and destructive orbits (see also Silsbee & Rafikov 2015a, 2015bSefilian 2017;Silsbee & Rafikov 2021;Best et al 2024), provided that the protoplanetary disk remains nearly axisymmetric (see, e.g., Marzari et al 2009Marzari et al , 2012. A related study by Batygin et al (2011b) has shown that massive protoplanetary disks can suppress and, in some cases, inhibit the Kozai-Lidov oscillations expected from a distant stellar companion on an inclined orbit.…”