2020/06/22 by Sivan Ginzburg, Eugene Chiang · 1 citation
Physics and Astronomy · #Accretion (finance) #Astro and Planetary Science #Astronomy #Astronomy and Astrophysical Research #Astrophysics #Exoplanet #Galaxy #Gas giant #Giant planet #Hot Jupiter #Metallicity #Physics #Planet #Planetary system #Stellar, planetary, and galactic studies #astro-ph.EP #astro-ph.SR
paper · pdf · doi:10.1093/mnras/staa2500
Submitted to MNRAS
arxiv created 2020/06/22 · openalex created_date 2020/06/25 · openalex publication_date 2020/08/17 · arxiv updated 2020/09/09 · openalex updated_date 2026/08/05
ABSTRACT Some Jupiter-mass exoplanets contain ∼100 \rm M_\hbox⊕ of metals, well above the ∼10 \rm M_\hbox⊕ typically needed in a solid core to trigger giant planet formation by runaway gas accretion. We demonstrate that such ‘heavy-metal Jupiters’ can result from planetary mergers near ∼10 au. Multiple cores accreting gas at runaway rates gravitationally perturb one another on to crossing orbits such that the average merger rate equals the gas accretion rate. Concurrent mergers and gas accretion implies the core mass scales with the total planet mass as Mcore ∝ M1/5 – heavier planets harbour heavier cores, in agreement with the observed relation between total mass and metal mass. While the average gas giant merges about once to double its core, others may merge multiple times, as merger trees grow chaotically. We show that the dispersion of outcomes inherent in mergers can reproduce the large scatter in observed planet metallicities, assuming 3-30 \rm M_\hbox⊕ pre-runaway cores. Mergers potentially correlate metallicity, eccentricity, and spin.