The Accretion Process on Protostars

TL;DR

This paper reviews recent observational and numerical findings on mass accretion in protostars, highlighting current methods, challenges, and future directions to better understand early stellar growth.

Contribution

It provides an updated, comprehensive assessment of accretion processes in protostars, bridging observational and numerical approaches and discussing methodological challenges.

Findings

Different techniques for measuring protostellar accretion are analyzed.

Methodological differences significantly impact parameter estimates.

The paper suggests future steps for a more complete understanding of protostellar accretion.

Abstract

The process of mass accretion onto Young Stellar Objects (YSOs) plays a fundamental role in determining the final stellar mass and setting the initial conditions for planet formation. Despite its critical role, our understanding of accretion remains fragmented, particularly for what concerns the earliest, protostellar phases (Class 0/I). While the community has consolidated a comprehensive knowledge of the accretion process of the later-stage Classical T Tauri Stars (CTTSs), a similar level of understanding is critically lacking for the protostellar phase, where the bulk of the mass is assembled. This work aims to review recent major results, both from the observational and numerical point of view, bridging the gap between the two approaches and providing an updated, complete assessment of accretion in protostellar sources. We present different techniques to measure accretion on protostars, analyze how methodological differences affect parameter estimation, discuss the caveats in comparing with numerical models, and suggest the next steps to take towards an ever more exhaustive picture of the protostellar phase.