Do we need to know the temperature in prestellar cores?

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.

ApJL, accepted

References in corpus (13)

• Systematic Molecular Differentiation in Starless Cores
• Observing the gas temperature drop in the high-density nucleus of L 1544
• The dust temperature distribution in prestellar cores
• Depletion and low gas temperature in the L183 prestellar core : the N2H+ - N2D+ tool
• The structure and stability of molecular cloud cores in external radiation fields
• The Thermal Structure of Gas in Pre-Stellar Cores: A Case Study of Barnard 68
• L1521E: the first starless core with no molecular depletion
• L1521E: A Starless Core in the Early Evolutionary Stage ?
• Line profiles of molecular ions toward the pre-stellar core LDN 1544
• CB17: Inferring the dynamical history of a prestellar core with chemo-dynamical models
• Abundances of Molecular Species in Barnard 68
• The dynamical influence of cooling in the envelope of prestellar and protostellar cores
• Photon Dominated Region Modeling of Barnard 68

Cited by in corpus (8)

• The Different Structures of the Two Classes of Starless Cores
• The Earliest Phases of Star formation observed with Herschel (EPoS): The dust temperature and density distributions of B68
• Detection of Structure in Infrared-Dark Clouds with Spitzer: Characterizing Star Formation in the Molecular Ring
• Gas-phase CO depletion and N2H+ abundances in starless cores
• Molecular Emission Line Formation in Prestellar Cores
• The Foggy Disks Surrounding Herbig Ae Stars: a Theoretical Study of the H2O Line Spectra
• The Earliest Phases of Star formation (EPoS): Temperature, density, and kinematic structure of the star-forming core CB 17
• Problems of Star Formation Theory and Prospects of Submillimeter Observations