Astro2020 Science White Paper: Measuring Protostar Masses: The Key to Protostellar Evolution

TL;DR

Measuring protostar masses through molecular line kinematics is crucial for understanding their evolution, requiring large samples and advanced facilities like ALMA, combined with spectroscopy and modeling, to constrain the protostellar mass function.

Contribution

This paper emphasizes the importance of observationally constraining the protostellar mass function using ALMA and other facilities, highlighting the need for large samples and improved techniques.

Findings

ALMA enables protostar mass measurements.

Large samples (~100 sources) are needed to constrain the protostellar mass function.

Combining spectroscopy and modeling enhances understanding of protostellar evolution.

Abstract

Knowledge of protostellar evolution has been revolutionized with the advent of surveys at near-infrared to submillimeter wavelengths. This has enabled the bolometric luminosities and bolometric temperatures (traditional protostellar evolution diagnostics) to be measured for large numbers of protostars. However, further progress is difficult without knowing the masses of the central protostars. Protostar masses can be most accurately determined via molecular line kinematics from millimeter interferometers (i.e., ALMA). Theoretical investigations have predicted the protostellar mass function (PMF) for various protostellar mass accretion models, and it is now imperative to observationally constrain its functional form. While ALMA has enabled protostellar mass measurements, samples approaching 100 sources are necessary to constrain the functional form of the PMF, and upgrades to ALMA and/or a new mm/cm facility will increase the feasibility of measuring such a large number of protostar masses. The masses of protostars will enable their stellar structure (radius and intrinsic luminosity), evolution, and accretion histories to be better understood. This is made more robust when effective temperatures and accretion rates can be measured via ground/space-based near to mid-infrared spectroscopy. Furthermore, access to supercomputing facilities is essential to fit the protostar masses via radiative transfer modeling and updated theoretical/numerical modeling of stellar structure may also be required.