Drozdovskaya, MN, Walsh, C orcid.org/0000-0001-6078-786X, Visser, R et al. (2 more authors) (2015) The complex chemistry of outflow cavity walls exposed: the case of low-mass protostars. Monthly Notices of the Royal Astronomical Society, 451 (4). pp. 3836-3856. ISSN 0035-8711
Abstract
Complex organic molecules are ubiquitous companions of young low-mass protostars. Recent observations suggest that their emission stems, not only from the traditional hot corino, but also from offset positions. In this work, 2D physicochemical modelling of an envelope-cavity system is carried out. Wavelength-dependent radiative transfer calculations are performed and a comprehensive gas-grain chemical network is used to simulate the physical and chemical structure. The morphology of the system delineates three distinct regions: the cavity wall layer with time-dependent and species-variant enhancements; a torus rich in complex organic ices, but not reflected in gas-phase abundances and the remaining outer envelope abundant in simpler solid and gaseous molecules. Strongly irradiated regions, such as the cavity wall layer, are subject to frequent photodissociation in the solid phase. Subsequent recombination of the photoproducts leads to frequent reactive desorption, causing gas-phase enhancements of several orders of magnitude. This mechanism remains to be quantified with laboratory experiments. Direct photodesorption is found to be relatively inefficient. If radicals are not produced directly in the icy mantle, the formation of complex organics is impeded. For efficiency, a sufficient number of FUV photons needs to penetrate the envelope, and elevated cool dust temperatures need to enable grain-surface radical mobility. As a result, a high stellar luminosity and a sufficiently wide cavity favour chemical complexity. Furthermore within this paradigm, complex organics are demonstrated to have unique lifetimes and be grouped into early (formaldehyde, ketene, methanol, formic acid, methyl formate, acetic acid and glycolaldehyde) and late (acetaldehyde, dimethyl ether and ethanol) species.
Metadata
Item Type: | Article |
---|---|
Authors/Creators: |
|
Copyright, Publisher and Additional Information: | © 2015 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved. This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society. Reproduced in accordance with the publisher's self-archiving policy. |
Keywords: | astrochemistry; stars: protostars |
Dates: |
|
Institution: | The University of Leeds |
Academic Units: | The University of Leeds > Faculty of Engineering & Physical Sciences (Leeds) > School of Physics and Astronomy (Leeds) > Astrophysics (Leeds) |
Depositing User: | Symplectic Publications |
Date Deposited: | 16 Nov 2016 12:21 |
Last Modified: | 16 Nov 2016 12:21 |
Published Version: | https://doi.org/10.1093/mnras/stv1177 |
Status: | Published |
Publisher: | Oxford University Press |
Identification Number: | 10.1093/mnras/stv1177 |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:107114 |