Astrochemical confirmation of the rapid evolution of massive YSOs and explanation for the inferred ages of hot cores

Abstract

Aims. To understand the roles of infall and protostellar evolution on the envelopes of massive young stellar objects (YSOs). Methods. The chemical evolution of gas and dust is traced, including infall and realistic source evolution. The temperatures are determined self-consistently. Both ad/desorption of ices using recent laboratory temperature-programmed-desorption measurements are included. Results. The observed water abundance jump near 100 K is reproduced by an evaporation front which moves outward as the luminosity increases. Ion-molecule reactions produce water below 100 K. The age of the source is constrained to t \~ 8 +/- 4 x 10^4 yrs since YSO formation. It is shown that the chemical age-dating of hot cores at ~ few x 10^3 - 10^4 yr and the disappearance of hot cores on a timescale of ~ 10^5 yr is a natural consequence of infall in a dynamic envelope and protostellar evolution. Dynamical structures of ~ 350AU such as disks should contain most of the complex second generation species. The assumed order of desorption kinetics does not affect these results.

arXiv commentAccepted by A&A Letters; 4 pages, 5 figures

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• Multidimensional chemical modelling, II. Irradiated outflow walls
• The SOFIA Massive (SOMA) Star Formation Survey. I. Overview and First Results
• Chemical complexity in high-mass star formation: An observational and modeling case study of the AFGL 2591 VLA 3 hot core
• Chemical Diversity in High-Mass Star Formation
• The Greenhouse Effect in Buried Galactic Nuclei and the Resonant HCN Vibrational Emission
• Evolution of complex organic molecules in hot molecular cores: Synthetic spectra at (sub-)mm wavebands
• Energetic radiation and the sulfur chemistry of protostellar envelopes: Submillimeter interferometry of AFGL 2591
• The methanol lines and hot core of OMC2-FIR4, an intermediate-mass protostar, with Herschel-HIFI
• Modeling the water line emission from the high-mass star-forming region AFGL2591