The Formation of Brown Dwarfs: Observations

TL;DR

This paper reviews observational evidence on brown dwarf formation, suggesting they form similarly to stars through cloud fragmentation, with some influence from other mechanisms, but no definitive evidence for alternative processes.

Contribution

It synthesizes current observational data to support a common formation mechanism for brown dwarfs and stars, emphasizing cloud fragmentation as primary.

Findings

Brown dwarfs share formation characteristics with stars.

Binary brown dwarfs and isolated proto-brown dwarfs support star-like formation.

No conclusive evidence for ejection or photoevaporation as primary formation mechanisms.

Abstract

We review the current state of observational work on the formation of brown dwarfs, focusing on their initial mass function, velocity and spatial distributions at birth, multiplicity, accretion, and circumstellar disks. The available measurements of these various properties are consistent with a common formation mechanism for brown dwarfs and stars. In particular, the existence of widely separated binary brown dwarfs and a probable isolated proto-brown dwarf indicate that some substellar objects are able to form in the same manner as stars through unperturbed cloud fragmentation. Additional mechanisms such as ejection and photoevaporation may play a role in the birth of some brown dwarfs, but there is no observational evidence to date to suggest that they are the key elements that make it possible for substellar bodies to form.