On the origin of planetary-mass objects in NGC1333

TL;DR

This study investigates the formation mechanisms of planetary-mass objects in NGC1333, finding evidence that they form like stars rather than planets, based on their spatial distribution and simulation analysis.

Contribution

It provides the first detailed spatial analysis of substellar objects in NGC1333 and compares observations with simulations to infer their formation process.

Findings

Planetary-mass objects share spatial distribution with stars and brown dwarfs.

Ejected planets would have different spatial and kinematic signatures.

Most low-mass objects likely formed through gravitational collapse, not planet-like formation.

Abstract

The dominant formation mechanism of brown dwarfs and planetary mass objects in star-forming regions is presently uncertain. Do they form like stars, via the collapse and fragmentation of cores in Giant Molecular clouds, or do they form like planets in the discs around stars and are ejected via dynamical interactions? In this paper, we quantify the spatial distribution of substellar objects in NGC1333, in particular focusing on planetary-mass objects that have been the target of recent deep imaging observations. We find that these objects have a spatial distribution that is indistinguishable from the stars, and more massive brown dwarfs. We also analyse N-body simulations and find that a population of ejected planets would have a significantly different spatial and kinematic distribution to stars, and brown dwarfs that also formed through gravitational collapse and fragmentation. We therefore conclude that the low-mass substellar objects in NGC1333 formed more like stars than planets, although we predict that a population of hitherto undetected ejected planetary mass objects may be lurking in this, and other star-forming regions.