Search for H3+ isotopologues toward CRL 2136 IRS 1

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dc.contributor University of Helsinki, Particle Physics and Astrophysics en Goto, Miwa Geballe, Thomas R. Harju, Jorma Caselli, Paola Sipilä, Olli Menten, Karl Usuda, Tomonori 2020-02-05T14:20:02Z 2020-02-05T14:20:02Z 2019-12
dc.identifier.citation Goto , M , Geballe , T R , Harju , J , Caselli , P , Sipilä , O , Menten , K & Usuda , T 2019 , ' Search for H3+ isotopologues toward CRL 2136 IRS 1 ' , Astronomy & Astrophysics , vol. 632 , A29 . en
dc.identifier.issn 0004-6361
dc.identifier.other PURE: 130918734
dc.identifier.other PURE UUID: 417c17b9-f9cf-4529-bc2c-3a191c60e486
dc.identifier.other ORCID: /0000-0002-1189-9790/work/68612424
dc.identifier.other WOS: 000515111600003
dc.description.abstract Context. Deuterated interstellar molecules frequently have abundances relative to their main isotopologues much higher than the overall elemental D-to-H ratio in the cold dense interstellar medium. H3+ and its isotopologues play a key role in the deuterium fractionation; however, the abundances of these isotopologues have not been measured empirically with respect to H3+ to date. Aims: Our aim was to constrain the relative abundances of H2D+ and D3+ in the cold outer envelope of the hot core CRL 2136 IRS 1. Methods: We carried out three observations targeting H3+ and its isotopologues using the spectrographs CRIRES at the VLT, iSHELL at IRTF, and EXES on board SOFIA. In addition, the CO overtone band at 2.3 μm was observed by iSHELL to characterize the gas on the line of sight. Results: The H3+ ion was detected toward CRL 2136 IRS 1 as in previous observations. Spectroscopy of lines of H2D+ and D3+ resulted in non-detections. The 3σ upper limits of N(H2D+)/N(H3+) and N(D3+)/N(H3+) are 0.24 and 0.13, respectively. The population diagram for CO is reproduced by two components of warm gas with the temperatures 58 and 530 K, assuming a local thermodynamic equilibrium (LTE) distribution of the rotational levels. Cold gas (<20 K) makes only a minor contribution to the CO molecular column toward CRL 2136 IRS 1. Conclusions: The critical conditions for deuterium fractionation in a dense cloud are low temperature and CO depletion. Given the revised cloud properties, it is no surprise that H3+ isotopologues are not detected toward CRL 2136 IRS 1. The result is consistent with our current understanding of how deuterium fractionation proceeds. en
dc.format.extent 9
dc.language.iso eng
dc.relation.ispartof Astronomy & Astrophysics
dc.rights en
dc.subject 115 Astronomy, Space science en
dc.subject astrochemistry; ISM: molecules; ISM: clouds; stars: individual: CRL 2136 IRS 1; ISM: lines and bands; infrared: ISM; Astrophysics - Solar and Stellar Astrophysics; Astrophysics - Astrophysics of Galaxies en
dc.title Search for H3+ isotopologues toward CRL 2136 IRS 1 en
dc.type Article
dc.description.version Peer reviewed
dc.description.version Peer reviewed
dc.type.uri info:eu-repo/semantics/other
dc.type.uri info:eu-repo/semantics/acceptedVersion
dc.type.uri info:eu-repo/semantics/publishedVersion

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