A Method to Constrain the Size of the Protosolar Nebula

TL;DR

This paper introduces a method to constrain the size of the early solar system's protoplanetary disk by analyzing the orbits of small bodies, using non-detections to rule out disks larger than 80 AU.

Contribution

It presents a novel dynamical approach linking small body orbital properties to the primordial disk size, providing new constraints on the early solar system.

Findings

Disks larger than 80 AU are inconsistent with observed small body orbits.

Non-detections of high-inclination, low-eccentricity objects constrain disk size.

Future surveys will refine these constraints further.

Abstract

Observations indicate that the gaseous circumstellar disks around young stars vary significantly in size, ranging from tens to thousands of AU. Models of planet formation depend critically upon the properties of these primordial disks, yet in general it is impossible to connect an existing planetary system with an observed disk. We present a method by which we can constrain the size of our own protosolar nebula using the properties of the small body reservoirs in the solar system. In standard planet formation theory, after Jupiter and Saturn formed they scattered a significant number of remnant planetesimals into highly eccentric orbits. In this paper, we show that if there had been a massive, extended protoplanetary disk at that time, then the disk would have excited Kozai oscillations in some of the scattered objects, driving them into high-inclination (i > 50 deg), low-eccentricity orbits (q > 30 AU). The dissipation of the gaseous disk would strand a subset of objects in these high-inclination orbits; orbits that are stable on Gyr time scales. To date, surveys have not detected any Kuiper Belt Objects with orbits consistent with this dynamical mechanism. Using these non-detections by the Deep Ecliptic Survey (DES) and the Palomar Distant Solar System Survey we are able to rule out an extended gaseous protoplanetary disk (R_D > 80 AU) in our solar system at the time of Jupiter's formation. Future deep all sky surveys such as the Large Synoptic Survey Telescope (LSST) will all us to further constrain the size of the protoplanetary disk.