Physical structure of the envelopes of intermediate-mass protostars

TL;DR

This study investigates the physical structure of intermediate-mass protostars, revealing their density profiles align with collapse models and suggesting a smooth transition in formation processes across different mass ranges.

Contribution

It provides a systematic analysis of intermediate-mass protostars' density and temperature profiles, comparing them with low- and high-mass protostars to understand their formation.

Findings

Density profiles consistent with inside-out collapse theory.

Physical parameters show a smooth transition across mass groups.

Formation processes appear similar across low, intermediate, and high-mass protostars.

Abstract

Context: Intermediate mass protostars provide a bridge between low- and high-mass protostars. Furthermore, they are an important component of the UV interstellar radiation field. Despite their relevance, little is known about their formation process. Aims: We present a systematic study of the physical structure of five intermediate mass, candidate Class 0 protostars. Our two goals are to shed light on the first phase of intermediate mass star formation and to compare these protostars with low- and high-mass sources. Methods: We derived the dust and gas temperature and density profiles of the sample. We analysed all existing continuum data on each source and modelled the resulting SED with the 1D radiative transfer code DUSTY. The gas temperature was then predicted by means of a modified version of the code CHT96. Results: We found that the density profiles of five out of six studied intermediate mass envelopes are consistent with the predictions of the "inside-out" collapse theory.We compared several physical parameters, like the power law index of the density profile, the size, the mass, the average density, the density at 1000 AU and the density at 10 K of the envelopes of low-, intermediate, and high-mass protostars. When considering these various physical parameters, the transition between the three groups appears smooth, suggesting that the formation processes and triggers do not substantially differ.