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Spectroscopic constraints on CH_3OH formation: CO mixed with CH_3OH ices towards young stellar objects

Penteado, E. M. and Boogert, A. C. A. and Pontoppidan, K. M. and Ioppolo, S. and Blake, G. A. and Cuppen, H. M. (2015) Spectroscopic constraints on CH_3OH formation: CO mixed with CH_3OH ices towards young stellar objects. Monthly Notices of the Royal Astronomical Society, 454 (1). pp. 531-540. ISSN 0035-8711. PMCID PMC6893920.

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The prominent infrared absorption band of solid CO – commonly observed towards young stellar objects (YSOs) – consists of three empirically determined components. The broad ‘red component’ (2136 cm^(−1), 4.681 μm) is generally attributed to solid CO mixed in a hydrogen-bonded environment. Usually, CO embedded in the abundantly present water is considered. However, CO:H_2O mixtures cannot reproduce the width and position of the observed red component without producing a shoulder at 2152 cm^(−1), which is not observed in astronomical spectra. Cuppen et al. showed that CO:CH_3OH mixtures do not suffer from this problem. Here, this proposition is expanded by comparing literature laboratory spectra of different CO-containing ice mixtures to high-resolution (R = λ/Δλ = 25 000) spectra of the massive YSO AFGL 7009S and of the low-mass YSO L1489 IRS. The previously unpublished spectrum of AFGL 7009S shows a wide band of solid ^(13)CO, the first detection of ^(13)CO ice in the polar phase. In this source, both the ^(12)CO and ^(13)CO ice bands are well fitted with CO:CH_3OH mixtures, while respecting the profiles and depths of the methanol bands at other wavelengths, whereas mixtures with H_2O cannot. The presence of a gradient in the CO:CH_3OH mixing ratio in the grain mantles is also suggested. Towards L1489 IRS, the profile of the ^(12)CO band is also better fitted with CH_3OH-containing ices, although the CH_3OH abundance needed is a factor of 2.4 above previous measurements. Overall, however, the results are reasonably consistent with models and experiments about formation of CH_3OH by the hydrogenation of CO ices.

Item Type:Article
Related URLs:
URLURL TypeDescription CentralArticle
Pontoppidan, K. M.0000-0001-7552-1562
Ioppolo, S.0000-0002-2271-1781
Blake, G. A.0000-0003-0787-1610
Alternate Title:Spectroscopic constraints on CH3OH formation: CO mixed with CH3OH ices towards young stellar objects
Additional Information:© 2015 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. Accepted 2015 August 21. Received 2015 August 21; in original form 2015 July 17. First published online September 22, 2015. EMP and HMC acknowledge the European Research Council (ERC-2010-StG, Grant Agreement no. 259510-KISMOL) for financial support. HMC is grateful for support from the VIDI research program 700.10.427, which is financed by The Netherlands Organization for Scientific Research (NWO). SI acknowledges financial support from the Royal Society. GAB gratefully acknowledges support from the NASA Origins of Solar Systems and NSF AAG programs.
Funding AgencyGrant Number
European Research Council (ERC)259510-KISMOL
Nederlandse Organisatie voor Wetenschappelijk Onderzoek (NWO)VIDI 700.10.427
Subject Keywords:astrochemistry – stars: formation – stars: individual: L1489 IRS, AFGL 7009S – ISM: abundances – ISM: molecules – infrared: ISM
Issue or Number:1
PubMed Central ID:PMC6893920
Record Number:CaltechAUTHORS:20151119-140540769
Persistent URL:
Official Citation:E. M. Penteado, A. C. A. Boogert, K. M. Pontoppidan, S. Ioppolo, G. A. Blake, and H. M. Cuppen Spectroscopic constraints on CH3OH formation: CO mixed with CH3OH ices towards young stellar objects MNRAS (November 21, 2015) Vol. 454 531-540 doi:10.1093/mnras/stv1987 First published online September 22, 2015
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:62257
Deposited By: George Porter
Deposited On:19 Nov 2015 23:52
Last Modified:09 Dec 2019 18:56

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