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Physical Properties of Molecular Envelopes in Low-Mass Star-Forming Regions

Published online by Cambridge University Press:  25 May 2016

Nagayoshi Ohashi
Nagayoshi Ohashi*
Affiliation:
Academia Sinica Institute of Astronomy & Astrophysics, P.O. Box 1-87, Nankang, Taipei 115, Taiwan

Abstract

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We have carried out interferometric observations of pre-protostellar and protostellar envelopes in Taurus. Protostellar envelopes are dense gaseous condensations with young stellar objects or protostars, while pre-protostellar envelopes are those without any known young stellar objects. Five pre-protostellar envelopes have been observed in CCS JN=32–21, showing flattened and clumpy structures of the envelopes. The observed CCS spectra show moderately narrow line widths, ~0.1 to ~0.35 km s–1. One pre-protostellar envelope, L1544, shows a remarkable velocity pattern, which can be explained in terms of infall and rotation. Our C18O J=1–0 observations of 8 protostellar envelopes show that they have also flattened structures like pre-protostellar envelopes but no clumpy structures. Four out the eight envelopes show velocity patterns that can be explained by motions of infall (and rotation). Physical properties of pre-protostellar and protostellar envelopes are discussed in detail.

Type
Part 1. Chemistry in Pre-Stellar Cores and Low-Mass Star-Forming Regions
Information
Symposium - International Astronomical Union , Volume 197: Astrochemistry: From Molecular Clouds to Planetary Systems , 2000 , pp. 61 - 70
Copyright
Copyright © Astronomical Society of the Pacific 2000 

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