He i in the central giant H ii region of NGC 5253: A 2D observational approach to collisional and radiative transfer effects

Context. NGC 5253 is a nearby peculiar blue compact dwarf (BCD) galaxy that, on account of its proximity, provides an ideal laboratory for detailed spatial study of starburst galaxies. An open issue not addressed so far is how the collisional and self-absorption effects on He i emission influence th...

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Authors: Monreal-Ibero, Ana, Walsh, J. R., Westmoquette, M. S., Vílchez Medina, José Manuel
Format: article
Status:Published version
Publication Date:2013
Country:España
Institution:Consejo Superior de Investigaciones Científicas (CSIC)
Repository:DIGITAL.CSIC. Repositorio Institucional del CSIC
OAI Identifier:oai:digital.csic.es:10261/404770
Online Access:http://hdl.handle.net/10261/404770
Access Level:Open access
Keyword:Galaxies: starburst
Galaxies: abundances
Galaxies: dwarf
Galaxies: individual: NGC 5253
Galaxies: ISM
Galaxies: kinematics and dynamics
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oai_identifier_str oai:digital.csic.es:10261/404770
network_acronym_str ES
network_name_str España
repository_id_str
dc.title.none.fl_str_mv He i in the central giant H ii region of NGC 5253: A 2D observational approach to collisional and radiative transfer effects
title He i in the central giant H ii region of NGC 5253: A 2D observational approach to collisional and radiative transfer effects
spellingShingle He i in the central giant H ii region of NGC 5253: A 2D observational approach to collisional and radiative transfer effects
Monreal-Ibero, Ana
Galaxies: starburst
Galaxies: abundances
Galaxies: dwarf
Galaxies: individual: NGC 5253
Galaxies: ISM
Galaxies: kinematics and dynamics
title_short He i in the central giant H ii region of NGC 5253: A 2D observational approach to collisional and radiative transfer effects
title_full He i in the central giant H ii region of NGC 5253: A 2D observational approach to collisional and radiative transfer effects
title_fullStr He i in the central giant H ii region of NGC 5253: A 2D observational approach to collisional and radiative transfer effects
title_full_unstemmed He i in the central giant H ii region of NGC 5253: A 2D observational approach to collisional and radiative transfer effects
title_sort He i in the central giant H ii region of NGC 5253: A 2D observational approach to collisional and radiative transfer effects
dc.creator.none.fl_str_mv Monreal-Ibero, Ana
Walsh, J. R.
Westmoquette, M. S.
Vílchez Medina, José Manuel
author Monreal-Ibero, Ana
author_facet Monreal-Ibero, Ana
Walsh, J. R.
Westmoquette, M. S.
Vílchez Medina, José Manuel
author_role author
author2 Walsh, J. R.
Westmoquette, M. S.
Vílchez Medina, José Manuel
author2_role author
author
author
dc.contributor.none.fl_str_mv Ministerio de Economía y Competitividad (España)
European Commission
Consejo Superior de Investigaciones Científicas (España)
European Southern Observatory
Consejo Superior de Investigaciones Científicas [https://ror.org/02gfc7t72]
dc.subject.none.fl_str_mv Galaxies: starburst
Galaxies: abundances
Galaxies: dwarf
Galaxies: individual: NGC 5253
Galaxies: ISM
Galaxies: kinematics and dynamics
topic Galaxies: starburst
Galaxies: abundances
Galaxies: dwarf
Galaxies: individual: NGC 5253
Galaxies: ISM
Galaxies: kinematics and dynamics
description Context. NGC 5253 is a nearby peculiar blue compact dwarf (BCD) galaxy that, on account of its proximity, provides an ideal laboratory for detailed spatial study of starburst galaxies. An open issue not addressed so far is how the collisional and self-absorption effects on He i emission influence the determination of the He+ abundance in 2D and what is the relation to the physical and chemical properties of the ionised gas. Aims. A 2D, imaging spectroscopy, study of the spatial behaviour of collisional and radiative transfer effects in He+ and their impact on the determination of He+ abundance is presented for the first time in a starburst galaxy. Methods. The He i lines were analysed based on previously presented integral field spectroscopy (IFS) data, obtained with FLAMES at the VLT and lower resolution gratings of the Giraffe spectrograph, as well as with GMOS at Gemini and the R381 grating. Results. Collisional effects reproduce the electron density (ne) structure. They are negligible (i.e. ~0.1-0.6%) for transitions in the singlet cascade but relatively important for those in the triplet cascade. In particular, they can contribute up to 20% of the flux in the He iλ7065 line. Radiative transfer effects are important over an extended and circular area of ~30 pc in diameter centred on the super star clusters (SSCs). The singly ionised helium abundance, y+, has been mapped using extinction-corrected fluxes of six He i lines, realistic assumptions for electron temperature (Te), ne, and the stellar absorption equivalent width, as well as the most recent emissivities. We find a mean(± standard deviation) of 103y+ ~ 80.3(± 2.7) over the mapped area. The relation between the excitation and the total helium abundance, ytot, is consistent with no abundance gradient. Uncertainties in the derivation of helium abundances are dominated by the adopted assumptions. We illustrate the difficulty of detecting a putative helium enrichment owing to the presence of Wolf-Rayet (WR) stars in the main GH iiR. Data are marginally consistent with an excess in the N/He ratio in the nitrogen-enriched area. This excess would be close to both the atmospheric N/He ratios in WR stars and the uncertainties estimated for the N/He ratios. We explored the influence of the kinematics in the evaluation of the He i radiative transfer effects. Our data empirically support the use of the traditional assumption that motions in an extragalactic H ii region have a negligible effect in the estimation of the global optical depths. Individually, the broad kinematic component (associated with an outflow) is affected by radiative transfer effects in a much more significant way than the narrow one. We find a relation between the amount of extra nitrogen and the upper limit of the contribution from radiative transfer effects that requires further investigation. We suggest that the electron temperature could be a common agent causing this relation. © ESO, 2013.
publishDate 2013
dc.date.none.fl_str_mv 2013
2025
2025
dc.type.none.fl_str_mv info:eu-repo/semantics/article
http://purl.org/coar/resource_type/c_6501
Publisher's version
info:eu-repo/semantics/publishedVersion
format article
status_str publishedVersion
dc.identifier.none.fl_str_mv http://hdl.handle.net/10261/404770
url http://hdl.handle.net/10261/404770
dc.language.none.fl_str_mv Inglés
language_invalid_str_mv Inglés
dc.relation.none.fl_str_mv #PLACEHOLDER_PARENT_METADATA_VALUE#
#PLACEHOLDER_PARENT_METADATA_VALUE#
info:eu-repo/grantAgreement/MICINN//AYA2010-21887-C04-01
info:eu-repo/grantAgreement/EC/FP7/229517
http://dx.doi.org/10.1051/0004-6361/201321387
Sí
dc.rights.none.fl_str_mv info:eu-repo/semantics/openAccess
eu_rights_str_mv openAccess
dc.publisher.none.fl_str_mv EDP Sciences
publisher.none.fl_str_mv EDP Sciences
dc.source.none.fl_str_mv reponame:DIGITAL.CSIC. Repositorio Institucional del CSIC
instname:Consejo Superior de Investigaciones Científicas (CSIC)
instname_str Consejo Superior de Investigaciones Científicas (CSIC)
reponame_str DIGITAL.CSIC. Repositorio Institucional del CSIC
collection DIGITAL.CSIC. Repositorio Institucional del CSIC
repository.name.fl_str_mv
repository.mail.fl_str_mv
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spelling He i in the central giant H ii region of NGC 5253: A 2D observational approach to collisional and radiative transfer effectsMonreal-Ibero, AnaWalsh, J. R.Westmoquette, M. S.Vílchez Medina, José ManuelGalaxies: starburstGalaxies: abundancesGalaxies: dwarfGalaxies: individual: NGC 5253Galaxies: ISMGalaxies: kinematics and dynamicsContext. NGC 5253 is a nearby peculiar blue compact dwarf (BCD) galaxy that, on account of its proximity, provides an ideal laboratory for detailed spatial study of starburst galaxies. An open issue not addressed so far is how the collisional and self-absorption effects on He i emission influence the determination of the He+ abundance in 2D and what is the relation to the physical and chemical properties of the ionised gas. Aims. A 2D, imaging spectroscopy, study of the spatial behaviour of collisional and radiative transfer effects in He+ and their impact on the determination of He+ abundance is presented for the first time in a starburst galaxy. Methods. The He i lines were analysed based on previously presented integral field spectroscopy (IFS) data, obtained with FLAMES at the VLT and lower resolution gratings of the Giraffe spectrograph, as well as with GMOS at Gemini and the R381 grating. Results. Collisional effects reproduce the electron density (ne) structure. They are negligible (i.e. ~0.1-0.6%) for transitions in the singlet cascade but relatively important for those in the triplet cascade. In particular, they can contribute up to 20% of the flux in the He iλ7065 line. Radiative transfer effects are important over an extended and circular area of ~30 pc in diameter centred on the super star clusters (SSCs). The singly ionised helium abundance, y+, has been mapped using extinction-corrected fluxes of six He i lines, realistic assumptions for electron temperature (Te), ne, and the stellar absorption equivalent width, as well as the most recent emissivities. We find a mean(± standard deviation) of 103y+ ~ 80.3(± 2.7) over the mapped area. The relation between the excitation and the total helium abundance, ytot, is consistent with no abundance gradient. Uncertainties in the derivation of helium abundances are dominated by the adopted assumptions. We illustrate the difficulty of detecting a putative helium enrichment owing to the presence of Wolf-Rayet (WR) stars in the main GH iiR. Data are marginally consistent with an excess in the N/He ratio in the nitrogen-enriched area. This excess would be close to both the atmospheric N/He ratios in WR stars and the uncertainties estimated for the N/He ratios. We explored the influence of the kinematics in the evaluation of the He i radiative transfer effects. Our data empirically support the use of the traditional assumption that motions in an extragalactic H ii region have a negligible effect in the estimation of the global optical depths. Individually, the broad kinematic component (associated with an outflow) is affected by radiative transfer effects in a much more significant way than the narrow one. We find a relation between the amount of extra nitrogen and the upper limit of the contribution from radiative transfer effects that requires further investigation. We suggest that the electron temperature could be a common agent causing this relation. © ESO, 2013.We are very grateful to the referee for the careful and diligent reading of the manuscript as well as for the useful comments that helped us to clarify and improve the first submitted version of this paper. Also, we thank R. L. Porter for advice on use of his tabulated He\u2009 i emissivities and for so promptly informing us of the Corrigendum. Based on observations carried out at the European Southern Observatory, Paranal (Chile), programmes 078.B-0043(A) and 383.B-0043(A). This paper uses the plotting package jmaplot , developed by Jes\u00FAs Ma\u00EDz-Apell\u00E1niz, http://dae45.iaa.csic.es:8080/~jmaiz/software . This research made use of the NASA/IPAC Extragalactic Database (NED), which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration. A.M.-I. is supported by the Spanish Research Council within the program JAE-Doc, Junta para la Ampliaci\u00F3n de Estudios, co-funded by the FSE. A.M.-I. is also grateful to ESO \u2013 Garching, where part of this work was carried out, for their hospitality and funding via their visitor program. This work has been partially funded by the Spanish PNAYA, project AYA2010-21887 of the Spanish MINECO. The research leading to these results has received funding from the European Community\u2019s Seventh Framework Programme (/FP7/2007-2013/) under grant agreement No 229517.Peer reviewedEDP SciencesMinisterio de Economía y Competitividad (España)European CommissionConsejo Superior de Investigaciones Científicas (España)European Southern ObservatoryConsejo Superior de Investigaciones Científicas [https://ror.org/02gfc7t72]202520252013info:eu-repo/semantics/articlehttp://purl.org/coar/resource_type/c_6501Publisher's versioninfo:eu-repo/semantics/publishedVersionhttp://hdl.handle.net/10261/404770reponame:DIGITAL.CSIC. Repositorio Institucional del CSICinstname:Consejo Superior de Investigaciones Científicas (CSIC)Inglés#PLACEHOLDER_PARENT_METADATA_VALUE##PLACEHOLDER_PARENT_METADATA_VALUE#info:eu-repo/grantAgreement/MICINN//AYA2010-21887-C04-01info:eu-repo/grantAgreement/EC/FP7/229517http://dx.doi.org/10.1051/0004-6361/201321387Síinfo:eu-repo/semantics/openAccessoai:digital.csic.es:10261/4047702026-05-22T06:33:51Z
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