Interstellar planetesimals: potential seeds for planet formation?

Abstract

We investigate the trapping of interstellar objects during the early stages of star and planet formation. Our results show a very wide range of possible values that will be narrowed down as the population of interstellar objects becomes better characterized. When assuming a background number density of 2$\cdot$10${}^{15}$ pc${}^{-3}$ (based on 1I/'Oumuamua detection), a velocity dispersion of 30 km/s and an equilibrium size distribution, the number of interstellar objects captured by a molecular cloud and expected to be incorporated to each protoplanetary disk during its formation is O(10${}^9$) (50 cm-5 m), O(10${}^5$) (5 m-50 m), O(10${}^2$) (50 m-500 m), O(10${}^{-2}$) (500 m-5 km). After the disk formed, the number of interstellar objects it could capture from the ISM during its lifetime is 6$\cdot$10${}^{11}$ (50 cm-5 m), 2$\cdot$10${}^8$ (5 m-50 m), 6$\cdot$10${}^4$ (50 m-500 m), 20 (500 m-5 km); in an open cluster where 1% of stars have undergone planet formation, these values increase by a factor of O(10${}^2$-10${}^3$). These trapped interstellar objects might be large enough to rapidly grow into larger planetesimals via the direct accretion of the sub-cm sized dust grains in the protoplanetary disk before they drift in due to gas drag, helping overcome the meter-size barrier, acting as "seeds" for planet formation. They should be considered in future star and planet formation models and in the potential spread of biological material across the Galaxy.

Accepted to ApJ. 32 pages, 10 figures

References in corpus (13)

• Dust size distributions in coagulation/fragmentation equilibrium: Numerical solutions and analytical fits
• Initial Characterization of Interstellar Comet 2I/2019 Q4 (Borisov)
• The Natural History of 'Oumuamua
• The Size Distribution of Kuiper belt objects for D> 10 km
• The central 1000 AU of a pre-stellar core revealed with ALMA. I. 1.3 mm continuum observations
• Evidence that 1I/2017 U1 (`Oumuamua) was composed of molecular hydrogen ice
• The Nucleus of Interstellar Comet 2I/Borisov
• Could 1I/'Oumuamua be an icy fractal aggregate?
• On the dynamics of dust during protostellar collapse
• 1I/'Oumuamua as an N2 ice fragment of an exo-Pluto surface: I. size and compositional constraints
• A hypothesis for the rapid formation of planets
• Comparing the Properties of GMCs in M33 from Simulations and Observations
• Survivor bias: divergent fates of the Solar System's ejected vs. persisting planetesimals

Cited by in corpus (7)

• Chasing Nomadic Worlds: A New Class of Deep Space Missions
• The New Astronomical Frontier of Interstellar Objects
• A Case Study of Interstellar Material Delivery: α Centauri
• The Implications of 'Oumuamua on Panspermia
• Eccentricity Evolution in Gaseous Dynamical Friction
• Close Encounters of the Interstellar Kind: Examining the Capture of Interstellar Objects in Near Earth Orbit
• A Catalogue of Interstellar Material Delivery From Nearby Debris Disks