LABOCA observations of giant molecular clouds in the southwest region of the Small Magellanic Cloud

Context. The amount of molecular gas is a key to understanding the future star formation in a galaxy. Because H2 is difficult to observe directly in dense and cold clouds, tracers such as the CO molecule are used. However, at low metallicities especially, CO only traces the shielded interiors of the...

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Autores: Bot, C., Rubio, M.
Tipo de recurso: artículo
Estado:Versión publicada
Fecha de publicación:2010
País:Chile
Idioma:inglés
OAI Identifier:oai:repositorio.anid.cl:10533/237202
Acceso en línea:https://hdl.handle.net/10533/237202
Access Level:acceso abierto
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spelling Rubio, M.Bot, C.201010.1051/0004-6361/200913372https://hdl.handle.net/10533/237202http://purl.org/coar/access_right/c_abf2LABOCA observations of giant molecular clouds in the southwest region of the Small Magellanic CloudBot, C.Rubio, M.2019-12-18T18:14:59Z2022-07-07T23:39:27Z2019-12-18T18:14:59Z2022-07-07T23:39:27Z2010Context. The amount of molecular gas is a key to understanding the future star formation in a galaxy. Because H2 is difficult to observe directly in dense and cold clouds, tracers such as the CO molecule are used. However, at low metallicities especially, CO only traces the shielded interiors of the clouds. In this context, millimeter dust emission can be used as a tracer to unveil the total dense gas masses. However, the comparison of masses deduced from the continuum SIMBA 1.2 mm emission and virial masses (understood to trace the entire potential of the clouds) in a sample of giant molecular clouds in the Small Magellanic Cloud (SMC) by previous studies found a discrepancy between these two quantities that requires explanation. Aims. We attempt to more accurately assess possible uncertainties in the dust emission observed in the sample of giant molecular clouds from the SMC. We focus on the mass comparison in the densest parts of the giant molecular clouds where CO is detected to confirm the mass discrepancy previously observed. Methods. New observations of the southwest region of the SMC were obtained with the LABOCA camera on the APEX telescope. All the giant molecular clouds previously observed in CO are detected and their emission at 870 μm is compared to ancillary data. The different contributions to the sub-millimeter emission are estimated, as well as dust properties (temperatures, emissivities), to determine molecular cloud masses precisely. Results. The (sub-)millimeter emission observed in the giant molecular clouds in the southwest region of the SMC is dominated by dust emission, and masses are deduced for the part of each cloud where CO is detected and compared to the virial masses. The mass discrepancy between both methods is confirmed at 870 μm using the LABOCA observations: the virial masses are on average 4 times lower than the masses of dense gas inferred from dust emission, in contrast to what is observed for equivalent clouds in our Galaxy. Conclusions. At present, the origin of this mass discrepancy in the SMC remains unknown. The direct interpretation of this effect is that the CO linewidth used to compute virial masses do not measure the full velocity distribution of the gas. Geometrical effects and uncertainties in the dust properties are also discussed.FONDAPFONDAP1501000315010003virtual::43087-1WOS:000284625300012https://hdl.handle.net/10533/237202enginstname: Conicytreponame: Repositorio Digital RI2.010.1051/0004-6361/200913372info:eu-repo/grantAgreement/Fondap/15010003https://www.aanda.org/articles/aa/abs/2010/16/aa13372-09/aa13372-09.htmlAtribución-NoComercial-SinDerivadas 3.0 Chilehttp://creativecommons.org/licenses/by-nc-nd/3.0/cl/info:eu-repo/semantics/openAccessLABOCA observations of giant molecular clouds in the southwest region of the Small Magellanic CloudAstronomy & AstrophysicsArticuloinfo:eu-repo/semantics/articleinfo:eu-repo/semantics/publishedVersionArticulohttps://hdl.handle.net/10533/237202http://purl.org/coar/resource_type/c_2df8fbb1045fc0e1-ef55-4532-8afe-69fe789d964dvirtual::43087-1045fc0e1-ef55-4532-8afe-69fe789d964dvirtual::43087-110533/237202oai:repositorio.anid.cl:10533/2372022023-07-24 16:56:59.724https://repositorio.anid.clRepositorio ANIDaletelier@anid.cl
dc.title.none.fl_str_mv LABOCA observations of giant molecular clouds in the southwest region of the Small Magellanic Cloud
dc.title.journal.none.fl_str_mv Astronomy & Astrophysics
title LABOCA observations of giant molecular clouds in the southwest region of the Small Magellanic Cloud
spellingShingle LABOCA observations of giant molecular clouds in the southwest region of the Small Magellanic Cloud
Bot, C.
title_short LABOCA observations of giant molecular clouds in the southwest region of the Small Magellanic Cloud
title_full LABOCA observations of giant molecular clouds in the southwest region of the Small Magellanic Cloud
title_fullStr LABOCA observations of giant molecular clouds in the southwest region of the Small Magellanic Cloud
title_full_unstemmed LABOCA observations of giant molecular clouds in the southwest region of the Small Magellanic Cloud
title_sort LABOCA observations of giant molecular clouds in the southwest region of the Small Magellanic Cloud
dc.creator.none.fl_str_mv Bot, C.
Rubio, M.
author Bot, C.
author_facet Bot, C.
Rubio, M.
author_role author
author2 Rubio, M.
author2_role author
description Context. The amount of molecular gas is a key to understanding the future star formation in a galaxy. Because H2 is difficult to observe directly in dense and cold clouds, tracers such as the CO molecule are used. However, at low metallicities especially, CO only traces the shielded interiors of the clouds. In this context, millimeter dust emission can be used as a tracer to unveil the total dense gas masses. However, the comparison of masses deduced from the continuum SIMBA 1.2 mm emission and virial masses (understood to trace the entire potential of the clouds) in a sample of giant molecular clouds in the Small Magellanic Cloud (SMC) by previous studies found a discrepancy between these two quantities that requires explanation. Aims. We attempt to more accurately assess possible uncertainties in the dust emission observed in the sample of giant molecular clouds from the SMC. We focus on the mass comparison in the densest parts of the giant molecular clouds where CO is detected to confirm the mass discrepancy previously observed. Methods. New observations of the southwest region of the SMC were obtained with the LABOCA camera on the APEX telescope. All the giant molecular clouds previously observed in CO are detected and their emission at 870 μm is compared to ancillary data. The different contributions to the sub-millimeter emission are estimated, as well as dust properties (temperatures, emissivities), to determine molecular cloud masses precisely. Results. The (sub-)millimeter emission observed in the giant molecular clouds in the southwest region of the SMC is dominated by dust emission, and masses are deduced for the part of each cloud where CO is detected and compared to the virial masses. The mass discrepancy between both methods is confirmed at 870 μm using the LABOCA observations: the virial masses are on average 4 times lower than the masses of dense gas inferred from dust emission, in contrast to what is observed for equivalent clouds in our Galaxy. Conclusions. At present, the origin of this mass discrepancy in the SMC remains unknown. The direct interpretation of this effect is that the CO linewidth used to compute virial masses do not measure the full velocity distribution of the gas. Geometrical effects and uncertainties in the dust properties are also discussed.
publishDate 2010
dc.date.issued.none.fl_str_mv 2010
dc.date.accessioned.none.fl_str_mv 2019-12-18T18:14:59Z
2022-07-07T23:39:27Z
dc.date.available.none.fl_str_mv 2019-12-18T18:14:59Z
2022-07-07T23:39:27Z
dc.type.none.fl_str_mv Articulo
dc.type.driver.none.fl_str_mv info:eu-repo/semantics/article
dc.type.openaire.none.fl_str_mv info:eu-repo/semantics/publishedVersion
format article
status_str publishedVersion
dc.identifier.folio.none.fl_str_mv 15010003
15010003
dc.identifier.idwos.none.fl_str_mv WOS:000284625300012
dc.identifier.uri.none.fl_str_mv https://hdl.handle.net/10533/237202
identifier_str_mv 15010003
WOS:000284625300012
url https://hdl.handle.net/10533/237202
dc.language.iso.none.fl_str_mv eng
language eng
dc.relation.none.fl_str_mv instname: Conicyt
reponame: Repositorio Digital RI2.0
dc.relation.doi.none.fl_str_mv 10.1051/0004-6361/200913372
dc.relation.projectid.none.fl_str_mv info:eu-repo/grantAgreement/Fondap/15010003
dc.relation.uri.none.fl_str_mv https://www.aanda.org/articles/aa/abs/2010/16/aa13372-09/aa13372-09.html
dc.rights.none.fl_str_mv Atribución-NoComercial-SinDerivadas 3.0 Chile
http://creativecommons.org/licenses/by-nc-nd/3.0/cl/
dc.rights.driver.none.fl_str_mv info:eu-repo/semantics/openAccess
rights_invalid_str_mv Atribución-NoComercial-SinDerivadas 3.0 Chile
http://creativecommons.org/licenses/by-nc-nd/3.0/cl/
eu_rights_str_mv openAccess
repository.name.fl_str_mv Repositorio ANID
repository.mail.fl_str_mv aletelier@anid.cl
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