Determination of rotational velocities in B and Be stars: physical processes and methods

In the present work we have used the method suggested by Carrol (1933) for the determination of the projected equatorial rotation velocity: v sin(i) by means of the Fourier Transform of a sample of B8 to B9.5 spectral type stars and luminosity classes III and V with Be and Bn type stars among them,...

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Detalles Bibliográficos
Autores principales: Díaz, A, Ringuelet, Adela Emilia
Formato: Articulo Comunicacion
Lenguaje:Español
Publicado: 1990
Materias:
Astronomía
Galaxia
Acceso en línea:http://sedici.unlp.edu.ar/handle/10915/143243
Aporte de:
SEDICI (UNLP) de Universidad Nacional de La Plata
id I19-R120-10915-143243
record_format dspace
institution Universidad Nacional de La Plata
institution_str I-19
repository_str R-120
collection SEDICI (UNLP)
language Español
topic Astronomía
Galaxia
spellingShingle Astronomía
Galaxia
Díaz, A
Ringuelet, Adela Emilia
Determination of rotational velocities in B and Be stars: physical processes and methods
topic_facet Astronomía
Galaxia
description In the present work we have used the method suggested by Carrol (1933) for the determination of the projected equatorial rotation velocity: v sin(i) by means of the Fourier Transform of a sample of B8 to B9.5 spectral type stars and luminosity classes III and V with Be and Bn type stars among them, which were observed by Baade (1989) with the Coudé Echelle spectrometer (C.E.S.) on the 1.4 m telescope (C.A.T.) at the E.S.O. The measured lines were MgII λ 4481 and HeI λ 4471 (this one was blended with [HeI] λ 4470 in some cases) and the signal to noise ratio was 1500. This method was tested with convolution of the rotational profile with the non-L.T.E. theoretical line profile of HeI λ 4471 (Teff = 20000 K, log(g) = 3.0) computed by Mihalas (1974) and then the Fourier transform was applied to the red wing of the profile and from it's zeroes the imposed values of v sin(i) were recovered. From the observed stars a very good correlation was obtained the rotation velocity from MgII λ 4481 measured in this work and Baade's determinations -which were obtained from the MgII λ 4481 full half width calibrated with the rotational velocities of the B.S.C. (Hoffleit, 1982)-. We obtained a linear relation between rotational velocities MgII λ 4481 and HeI λ 4471 up to v sin(i) < 140 km/s and beyond this value HeI yields greater velocities than MgII. We concluded that the formation region of HeI λ4471 is affected by non rigid rotational laws, in special for high rotators where this region could be quite large.
format Articulo
Comunicacion
author Díaz, A
Ringuelet, Adela Emilia
author_facet Díaz, A
Ringuelet, Adela Emilia
author_sort Díaz, A
title Determination of rotational velocities in B and Be stars: physical processes and methods
title_short Determination of rotational velocities in B and Be stars: physical processes and methods
title_full Determination of rotational velocities in B and Be stars: physical processes and methods
title_fullStr Determination of rotational velocities in B and Be stars: physical processes and methods
title_full_unstemmed Determination of rotational velocities in B and Be stars: physical processes and methods
title_sort determination of rotational velocities in b and be stars: physical processes and methods
publishDate 1990
url http://sedici.unlp.edu.ar/handle/10915/143243
work_keys_str_mv AT diaza determinationofrotationalvelocitiesinbandbestarsphysicalprocessesandmethods
AT ringueletadelaemilia determinationofrotationalvelocitiesinbandbestarsphysicalprocessesandmethods
bdutipo_str Repositorios
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