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ALMA observations of water deuteration: A physical diagnostic of the formation of protostars

dc.contributor.authorJENSEN, S. S.
hal.structure.identifierforeign laboratories [FL]
dc.contributor.authorJØRGENSEN, J. K.
hal.structure.identifierLeiden Observatory [Leiden]
dc.contributor.authorKRISTENSEN, L. E.
dc.contributor.authorFURUYA, K.
hal.structure.identifierAMOR 2019
dc.contributor.authorCOUTENS, Audrey
hal.structure.identifierLeiden Observatory [Leiden]
dc.contributor.authorVAN DISHOECK, E. F.
dc.contributor.authorHARSONO, D.
dc.contributor.authorPERSSON, M. V.
dc.date.issued2019
dc.identifier.issn0004-6361
dc.description.abstractEnThe deuterium fractionation of water can serve as a tracer for the chemical and physical evolution of water during star formation and can constrain the origin of water in Solar System bodies. We determine the HDO/H$_2$O ratio in the inner warm gas toward three low-mass Class 0 protostars selected to be in isolated cores, i.e., not associated with any cloud complexes. Previous sources for which the HDO/H$_2$O ratio have been established were all part of larger star-forming complexes. Targeting these isolated protostars allows comparison of the water chemistry in isolated and clustered regions to determine the influence of local cloud environment. We present ALMA observations of the HDO $3_{1,2}$-$2_{2,1}$ and $2_{1,1}$-$2_{1,2}$ transitions at 225.897 GHz and 241.562 GHz along with the H$_2^{18}$O $3_{1,3}$-$2_{2,0}$ transition at 203.407 GHz. The high angular resolution (0\farcs3-1\farcs3) allow the study of the inner warm envelope gas. Model-independent estimates for the HDO/H$_2$O ratios are obtained and compared with previous determinations in the warm gas toward low-mass protostars. We detect the targeted water transitions toward the three sources with S/N > 5. We determine the HDO/H$_2$O ratio toward L483, B335 and BHR71-IRS1 to be ($2.2\pm0.4$)$\times 10^{-3}$, ($1.7\pm0.3$)$\times 10^{-3}$, and ($1.8\pm0.4$)$\times 10^{-3}$, respectively, assuming $T_\mathrm{ex} = 124$ K. The degree of water deuteration of these isolated protostars are a factor of 2-4 higher relative to Class 0 protostars that are members of known nearby clustered star-forming regions. The results indicate that the water deuterium fractionation is influenced by the local cloud environment. This effect can be explained by variations in either collapse timescales or temperatures, which depends on local cloud dynamics and could provide a new method to decipher the history of young stars.
dc.language.isoen
dc.publisherEDP Sciences
dc.subject.enAstrophysics - Solar and Stellar Astrophysics
dc.subject.enAstrophysics - Astrophysics of Galaxies
dc.title.enALMA observations of water deuteration: A physical diagnostic of the formation of protostars
dc.typeArticle de revue
dc.identifier.doi10.1051/0004-6361/201936012
dc.subject.halPlanète et Univers [physics]/Astrophysique [astro-ph]/Cosmologie et astrophysique extra-galactique [astro-ph.CO]
dc.identifier.arxiv1909.10533
bordeaux.journalAstronomy and Astrophysics - A&A
bordeaux.pageid.A25
bordeaux.volume631
bordeaux.peerReviewedoui
hal.identifierhal-02298716
hal.version1
hal.popularnon
hal.audienceInternationale
hal.origin.linkhttps://hal.archives-ouvertes.fr//hal-02298716v1
bordeaux.COinSctx_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:journal&rft.jtitle=Astronomy%20and%20Astrophysics%20-%20A&A&rft.date=2019&rft.volume=631&rft.spage=id.A25&rft.epage=id.A25&rft.eissn=0004-6361&rft.issn=0004-6361&rft.au=JENSEN,%20S.%20S.&J%C3%98RGENSEN,%20J.%20K.&KRISTENSEN,%20L.%20E.&FURUYA,%20K.&COUTENS,%20Audrey&rft.genre=article


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