A CNO Dichotomy among O2 Giant Spectra in the Magellanic Clouds

From a survey of the 3400 Å region in the earliest O-type spectra, we have found that two of the four O2 giants observed in the Large Magellanic Cloud have O IV lines there that are stronger than the N IV lines, while the other two have the opposite. A Small Magellanic Cloud counterpart also has N I...

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Authors: Walborn, Nolan Revere, Morrell, Nidia Irene, Howarth, Ian D., Crowther, Paul A., Lennon, Daniel J., Massey, Philip, Arias, Julia Ines
Format: article
Status:Published version
Publication Date:2004
Country:Argentina
Institution:Consejo Nacional de Investigaciones Científicas y Técnicas
Repository:CONICET Digital (CONICET)
Language:English
OAI Identifier:oai:ri.conicet.gov.ar:11336/37076
Online Access:http://hdl.handle.net/11336/37076
Access Level:Open access
Keyword:Magellanic Clouds
Abundances
Early type stars
Evolution of stars
Fundamental parameters
https://purl.org/becyt/ford/1.3
https://purl.org/becyt/ford/1
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spelling A CNO Dichotomy among O2 Giant Spectra in the Magellanic CloudsWalborn, Nolan RevereMorrell, Nidia IreneHowarth, Ian D.Crowther, Paul A.Lennon, Daniel J.Massey, PhilipArias, Julia InesMagellanic CloudsAbundancesEarly type starsEvolution of starsFundamental parametershttps://purl.org/becyt/ford/1.3https://purl.org/becyt/ford/1From a survey of the 3400 Å region in the earliest O-type spectra, we have found that two of the four O2 giants observed in the Large Magellanic Cloud have O IV lines there that are stronger than the N IV lines, while the other two have the opposite. A Small Magellanic Cloud counterpart also has N IV stronger than O IV. Inspection of the blue spectra of these stars shows that the former pair have weaker N lines in all ionization states (III, IV, and V) present as well as lines of C IV λ4658, while the latter three have stronger N lines and greater He/H. Space ultraviolet observations of two of the N-strong stars show N V wind profiles substantially stronger than those of C IV, while in the N-weak stars the C IV features are equal to or stronger than the N V. The N-strong stars are now reclassified as ON2 III(f*), newly defining that category. These characteristics strongly suggest a larger fraction of processed material in the atmospheres of the ON2 stars, which we confirm by modeling the optical spectra. In the context of current models, it is in turn implied that the ON2 stars are in a more advanced evolutionary state than the others, and/or that they had higher initial rotational velocities. The recent formulation of the effects of rotation on massive stellar evolution introduces an additional fundamental parameter, which the CNO abundances are in principle able to constrain. We present some illustrative comparisons with current Geneva evolutionary models for rotating massive stars. It is possible that these very hot, nitrogen-rich objects are products of homogeneous evolution. Our results will provide motivation for further physical modeling of the atmospheres and evolutionary histories of the most massive hot stars.Fil: Walborn, Nolan Revere. Space Telescope Science Institute; Estados UnidosFil: Morrell, Nidia Irene. Las campanas observatory; ChileFil: Howarth, Ian D.. University College London; Estados UnidosFil: Crowther, Paul A.. University of Sheffield; Reino UnidoFil: Lennon, Daniel J.. Isaac Newton Group of Telescopes; EspañaFil: Massey, Philip. Lowell Observatory; Estados UnidosFil: Arias, Julia Ines. Universidad Nacional de la Plata. Facultad de Ciencias Astronómicas y Geofísicas; ArgentinaIOP Publishing2004-06info:eu-repo/semantics/articleinfo:eu-repo/semantics/publishedVersionhttp://purl.org/coar/resource_type/c_6501info:ar-repo/semantics/articuloapplication/pdfapplication/pdfhttp://hdl.handle.net/11336/37076Walborn, Nolan Revere; Morrell, Nidia Irene; Howarth, Ian D.; Crowther, Paul A.; Lennon, Daniel J.; et al.; A CNO Dichotomy among O2 Giant Spectra in the Magellanic Clouds; IOP Publishing; Astrophysical Journal; 608; 2; 6-2004; 1028-10380004-637XCONICET DigitalCONICETenginfo:eu-repo/semantics/altIdentifier/doi/10.1086/420761info:eu-repo/semantics/altIdentifier/url/http://iopscience.iop.org/article/10.1086/420761/metainfo:eu-repo/semantics/openAccesshttps://creativecommons.org/licenses/by-nc-sa/2.5/ar/reponame:CONICET Digital (CONICET)instname:Consejo Nacional de Investigaciones Científicas y Técnicas2024-05-08T13:33:21Zoai:ri.conicet.gov.ar:11336/37076instacron:CONICETInstitucionalhttp://ri.conicet.gov.ar/Organismo científico-tecnológicoNo correspondehttp://ri.conicet.gov.ar/oai/requestdasensio@conicet.gov.ar; lcarlino@conicet.gov.arArgentinaNo correspondeNo correspondeNo correspondeopendoar:34982024-05-08 13:33:22.063CONICET Digital (CONICET) - Consejo Nacional de Investigaciones Científicas y Técnicasfalse
dc.title.none.fl_str_mv A CNO Dichotomy among O2 Giant Spectra in the Magellanic Clouds
title A CNO Dichotomy among O2 Giant Spectra in the Magellanic Clouds
spellingShingle A CNO Dichotomy among O2 Giant Spectra in the Magellanic Clouds
Walborn, Nolan Revere
Magellanic Clouds
Abundances
Early type stars
Evolution of stars
Fundamental parameters
https://purl.org/becyt/ford/1.3
https://purl.org/becyt/ford/1
title_short A CNO Dichotomy among O2 Giant Spectra in the Magellanic Clouds
title_full A CNO Dichotomy among O2 Giant Spectra in the Magellanic Clouds
title_fullStr A CNO Dichotomy among O2 Giant Spectra in the Magellanic Clouds
title_full_unstemmed A CNO Dichotomy among O2 Giant Spectra in the Magellanic Clouds
title_sort A CNO Dichotomy among O2 Giant Spectra in the Magellanic Clouds
dc.creator.none.fl_str_mv Walborn, Nolan Revere
Morrell, Nidia Irene
Howarth, Ian D.
Crowther, Paul A.
Lennon, Daniel J.
Massey, Philip
Arias, Julia Ines
author Walborn, Nolan Revere
author_facet Walborn, Nolan Revere
Morrell, Nidia Irene
Howarth, Ian D.
Crowther, Paul A.
Lennon, Daniel J.
Massey, Philip
Arias, Julia Ines
author_role author
author2 Morrell, Nidia Irene
Howarth, Ian D.
Crowther, Paul A.
Lennon, Daniel J.
Massey, Philip
Arias, Julia Ines
author2_role author
author
author
author
author
author
dc.subject.none.fl_str_mv Magellanic Clouds
Abundances
Early type stars
Evolution of stars
Fundamental parameters
https://purl.org/becyt/ford/1.3
https://purl.org/becyt/ford/1
topic Magellanic Clouds
Abundances
Early type stars
Evolution of stars
Fundamental parameters
https://purl.org/becyt/ford/1.3
https://purl.org/becyt/ford/1
description From a survey of the 3400 Å region in the earliest O-type spectra, we have found that two of the four O2 giants observed in the Large Magellanic Cloud have O IV lines there that are stronger than the N IV lines, while the other two have the opposite. A Small Magellanic Cloud counterpart also has N IV stronger than O IV. Inspection of the blue spectra of these stars shows that the former pair have weaker N lines in all ionization states (III, IV, and V) present as well as lines of C IV λ4658, while the latter three have stronger N lines and greater He/H. Space ultraviolet observations of two of the N-strong stars show N V wind profiles substantially stronger than those of C IV, while in the N-weak stars the C IV features are equal to or stronger than the N V. The N-strong stars are now reclassified as ON2 III(f*), newly defining that category. These characteristics strongly suggest a larger fraction of processed material in the atmospheres of the ON2 stars, which we confirm by modeling the optical spectra. In the context of current models, it is in turn implied that the ON2 stars are in a more advanced evolutionary state than the others, and/or that they had higher initial rotational velocities. The recent formulation of the effects of rotation on massive stellar evolution introduces an additional fundamental parameter, which the CNO abundances are in principle able to constrain. We present some illustrative comparisons with current Geneva evolutionary models for rotating massive stars. It is possible that these very hot, nitrogen-rich objects are products of homogeneous evolution. Our results will provide motivation for further physical modeling of the atmospheres and evolutionary histories of the most massive hot stars.
publishDate 2004
dc.date.none.fl_str_mv 2004-06
dc.type.none.fl_str_mv info:eu-repo/semantics/article
info:eu-repo/semantics/publishedVersion
http://purl.org/coar/resource_type/c_6501
info:ar-repo/semantics/articulo
format article
status_str publishedVersion
dc.identifier.none.fl_str_mv http://hdl.handle.net/11336/37076
Walborn, Nolan Revere; Morrell, Nidia Irene; Howarth, Ian D.; Crowther, Paul A.; Lennon, Daniel J.; et al.; A CNO Dichotomy among O2 Giant Spectra in the Magellanic Clouds; IOP Publishing; Astrophysical Journal; 608; 2; 6-2004; 1028-1038
0004-637X
CONICET Digital
CONICET
url http://hdl.handle.net/11336/37076
identifier_str_mv Walborn, Nolan Revere; Morrell, Nidia Irene; Howarth, Ian D.; Crowther, Paul A.; Lennon, Daniel J.; et al.; A CNO Dichotomy among O2 Giant Spectra in the Magellanic Clouds; IOP Publishing; Astrophysical Journal; 608; 2; 6-2004; 1028-1038
0004-637X
CONICET Digital
CONICET
dc.language.none.fl_str_mv eng
language eng
dc.relation.none.fl_str_mv info:eu-repo/semantics/altIdentifier/doi/10.1086/420761
info:eu-repo/semantics/altIdentifier/url/http://iopscience.iop.org/article/10.1086/420761/meta
dc.rights.none.fl_str_mv info:eu-repo/semantics/openAccess
https://creativecommons.org/licenses/by-nc-sa/2.5/ar/
eu_rights_str_mv openAccess
rights_invalid_str_mv https://creativecommons.org/licenses/by-nc-sa/2.5/ar/
dc.format.none.fl_str_mv application/pdf
application/pdf
dc.publisher.none.fl_str_mv IOP Publishing
publisher.none.fl_str_mv IOP Publishing
dc.source.none.fl_str_mv reponame:CONICET Digital (CONICET)
instname:Consejo Nacional de Investigaciones Científicas y Técnicas
instname_str Consejo Nacional de Investigaciones Científicas y Técnicas
reponame_str CONICET Digital (CONICET)
collection CONICET Digital (CONICET)
repository.name.fl_str_mv CONICET Digital (CONICET) - Consejo Nacional de Investigaciones Científicas y Técnicas
repository.mail.fl_str_mv dasensio@conicet.gov.ar; lcarlino@conicet.gov.ar
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score 15,812429

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