Do we need to know the temperature in prestellar cores?

TL;DR

This paper emphasizes the importance of accurately modeling temperature variations in prestellar cores, showing that assuming isothermality can lead to misinterpretation of molecular line observations and core properties.

Contribution

It demonstrates that small temperature differences within prestellar cores significantly affect molecular line profiles and derived chemical abundances, challenging the common isothermal assumption.

Findings

Isothermal models can misrepresent molecular line profiles.

Temperature variations influence the interpretation of core chemistry.

Assuming isothermality may lead to incorrect core property estimates.

Abstract

Molecular line observations of starless (prestellar) cores combined with a chemical evolution modeling and radiative transfer calculations are a powerful tool to study the earliest stages of star formation. However, conclusions drawn from such a modeling may noticeably depend on the assumed thermal structure of the cores. The assumption of isothermality, which may work well in chemo-dynamical studies, becomes a critical factor in molecular line formation simulations. We argue that even small temperature variations, which are likely to exist in starless cores, can have a non-negligible effect on the interpretation of molecular line data and derived core properties. In particular, ``chemically pristine'' isothermal cores (low depletion) can have centrally peaked C$^{18}$O and C$^{34}$S radial intensity profiles, while having ring-like intensity distributions in models with a colder center and/or warmer envelope assuming the same underlying chemical structure. Therefore, derived molecular abundances based on oversimplified thermal models may lead to a mis-interpretation of the line data.