Chemistry in the Envelopes around Massive Young Stars

Abstract

Recent observational studies of intermediate- and high-mass star-forming regions at submillimeter and infrared wavelengths are reviewed, and chemical diagnostics of the different physical components associated with young stellar objects are summarized. Procedures for determining the temperature, density and abundance profiles in the envelopes are outlined. A detailed study of a set of infrared-bright massive young stars reveals systematic increases in the gas/solid ratios, the abundances of evaporated molecules, and the fraction of heated ices with increasing temperature. Since these diverse phenomena involve a range of temperatures from < 100 K to 1000 K, the enhanced temperatures must be communicated to both the inner and outer parts of the envelopes. This `global heating' plausibly results from the gradual dispersion of the envelopes with time. Similarities and differences with low-mass YSOs are discussed. The availability of accurate physical models will allow chemical models of ice evaporation followed by `hot core' chemistry to be tested in detail.

arXiv comment16 pages, 6 figures, to be published in IAU Symposium 197, Astrochemistry: from Molecular Clouds to Planetary Systems, eds. Y.C. Minh and E.F. van Dishoeck, ASP (uses newpasp.sty)

References in corpus (7)

• Massive Stars: Their Environment and Formation
• Structure and Evolution of the Envelopes of Deeply Embedded Massive Young Stars
• The Impact of the Massive Young Star GL 2591 on its Circumstellar Material: Temperature, Density and Velocity Structure
• Envelope structure of deeply embedded young stellar objects in the Serpens Molecular Cloud
• Models for Dense Molecular Cloud Cores
• Thermal Water Vapor Emission from Shocked Regions in Orion
• Observation of Infrared and Radio Lines of Molecules toward GL2591 and Comparison to Physical and Chemical Models

Cited by in corpus (5)

• ISO spectroscopy of gas and dust: from molecular clouds to protoplanetary disks
• Chemistry as a probe of the structures and evolution of massive star forming regions
• Physical-chemical modeling of the low-mass protostar IRAS 16293-2422
• Gas-phase H2O and CO2 toward massive protostars
• Highly abundant HCN in the inner hot envelope of GL 2591: probing the birth of a hot core?