A survey of N IV and O IV features near 3400 Å in O2-O5 spectra

We have conducted a survey of little-known N IV and O IV multiplets near 3400 Å in an extensive sample of well-classified, very early O-type spectra. The initial motivation was to search for additional useful classification criteria for these types, but an unexpected result is the high sensitivity o...

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Detalles Bibliográficos
Autores principales: Morrell, Nidia Irene, Walborn, Nolan Revere, Arias, Julia Inés
Formato: Articulo
Lenguaje:Inglés
Publicado: 2005
Materias:
Ciencias Astronómicas
O-type spectra
spectral types O4 and O5
Acceso en línea:http://sedici.unlp.edu.ar/handle/10915/84411
Aporte de:
SEDICI (UNLP) de Universidad Nacional de La Plata
id I19-R120-10915-84411
record_format dspace
institution Universidad Nacional de La Plata
institution_str I-19
repository_str R-120
collection SEDICI (UNLP)
language Inglés
topic Ciencias Astronómicas
O-type spectra
spectral types O4 and O5
spellingShingle Ciencias Astronómicas
O-type spectra
spectral types O4 and O5
Morrell, Nidia Irene
Walborn, Nolan Revere
Arias, Julia Inés
A survey of N IV and O IV features near 3400 Å in O2-O5 spectra
topic_facet Ciencias Astronómicas
O-type spectra
spectral types O4 and O5
description We have conducted a survey of little-known N IV and O IV multiplets near 3400 Å in an extensive sample of well-classified, very early O-type spectra. The initial motivation was to search for additional useful classification criteria for these types, but an unexpected result is the high sensitivity of these features to evolutionary CNO processing. We have found a useful discriminant between O2 and later types in the relative strengths of the O IV multiplets, one of which is subject to selective emission in the hottest spectra; the overall strengths of these lines also decrease between spectral types O4 and O5. More remarkable, however, are the variations in the N/O ratios among both individual stars and clusters. For instance, several O4 If + spectra have very large ratios, while main-sequence stars in the Carina Nebula generally have smaller values than others of the same spectral types in other regions. These effects correspond to different degrees of mixing of processed material as a function of evolutionary age and initial rotational velocities; the second effect provides significant further evidence that very massive stars mix while still on the main sequence. Thus, further analysis of these features will likely provide valuable diagnostics of important evolutionary parameters.
format Articulo
Articulo
author Morrell, Nidia Irene
Walborn, Nolan Revere
Arias, Julia Inés
author_facet Morrell, Nidia Irene
Walborn, Nolan Revere
Arias, Julia Inés
author_sort Morrell, Nidia Irene
title A survey of N IV and O IV features near 3400 Å in O2-O5 spectra
title_short A survey of N IV and O IV features near 3400 Å in O2-O5 spectra
title_full A survey of N IV and O IV features near 3400 Å in O2-O5 spectra
title_fullStr A survey of N IV and O IV features near 3400 Å in O2-O5 spectra
title_full_unstemmed A survey of N IV and O IV features near 3400 Å in O2-O5 spectra
title_sort survey of n iv and o iv features near 3400 å in o2-o5 spectra
publishDate 2005
url http://sedici.unlp.edu.ar/handle/10915/84411
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