![Disk properties [Ri,Rco,Rdust] and exoplanet semimajor axis values are plotted in units of the PMS host stellar radius as a function of host star mass. The plot shows planets are less common inside the disk corotation radius suggesting that planetary inward migration is frequently halted in the vicinity of the corotation radius. Some planets have semimajor axis values < Rdust the dust sublimation radius, implying that planet migration must have occurred to populate the semimajor axis < Rdust region. Ri & Rco (gray diamonds and red squares respectively) are from the Pittman et al. (2025b) survey. -- [astro-ph.EP]](https://i0.wp.com/astrobiology.com/wp-content/uploads/2026/09/Exoplanet-System.png?fit=1200%2C676&ssl=1)
[astro-ph.EP] In this study, we seek to improve our understanding of the competing roles of disk-driven and planet-planet dynamical migration in sculpting planetary system architecture in the inner ≲1.5 au of protoplanetary disks.
Over a range of host star masses, we compare the orbit semimajor axis values of transiting multi-planet and resonant systems to observationally-derived estimates of protoplanetary disk inner truncation radius Ri, corotation radius Rco, and dust sublimation radius Rdust.
We find that disk-driven migration is primarily responsible for setting the inner edge of planetary systems near Rco and that subsequent dynamical migration shapes the distribution of planetary semimajor axis values over the range ≈20−300 R⋆.
If multi-planet systems form in a way similar to the resonant chain systems, either a zone of highly efficient planet formation at ≳100R⋆, followed by subsequent disk-driven migration, is implied, or a modified in-situ mechanism operating over a region from ≃15−100R⋆ and incorporating disk-driven migration is needed.
There are indications that after disk dispersal, dynamical migration causes a subset of planets to migrate to locations inside Rco.
Mark R. Swain, Geoffrey Bryden, Jonathan C. Tan, Eric Gaidos, George Zhou, Caeley V. Pittman, Christopher M. Johns-Krull, Ann Marie Cody, Meredith A. MacGregor, Laura Venuti, Aayush Gautam, Neal Turner, Zhaohuan Zhu, Evgenya Shkolnik, Connor Robinson, Valerie Scott, John Arballo
Comments: submitted to AAS Journals
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Cite as: arXiv:2608.22649 [astro-ph.EP] (or arXiv:2608.22649v1 [astro-ph.EP] for this version)
https://doi.org/10.48550/arXiv.2608.22649
Focus to learn more
Submission history
From: Mark Swain
[v1] Sun, 23 Aug 2026 23:15:29 UTC (1,814 KB)
https://arxiv.org/abs/2608.22649
Astrobiology
