The Inevitable Future of the Starless Core Barnard 68

TL;DR

This paper suggests that Barnard 68, a prototypical molecular cloud core, is currently undergoing a collision that will lead to its gravitational collapse and star formation within 200,000 years, highlighting core mergers' role in star formation.

Contribution

It introduces the idea that core collisions can trigger collapse and star formation, supported by numerical simulations of Barnard 68's future evolution.

Findings

Barnard 68 is likely experiencing a collision leading to collapse.

Simulations predict star formation in Barnard 68 within 200,000 years.

Core mergers may influence the initial mass function of stars.

Abstract

Dense, small molecular cloud cores have been identified as the direct progenitors of stars. One of the best studied examples is Barnard 68 which is considered a prototype stable, spherical gas core, confined by a diffuse high-pressure environment. Observations of its radial density structure however indicate that Barnard 68 should be gravitationally unstable and collapsing which appears to be inconsistent with its inferred long lifetime and stability. We argue that Barnard 68 is currently experiencing a fatal collision with another small core which will lead to gravitational collapse. Despite the fact that this system is still in an early phase of interaction, our numerical simulations imply that the future gravitational collapse is already detectable in the outer surface density structure of the globule which mimicks the profile of a gravitationally unstable Bonnor-Ebert sphere. Within the next 200,000 years Barnard 68 will condense into a low-mass solar-type star(s), formed in isolation, and surrounded by diffuse, hot interstellar gas. As witnessed in situ for Barnard 68, core mergers might in general play an important role in triggering star formation and shaping the molecular core mass distribution and by that also the stellar initial mass function.