Rotational Velocities for the Brighter A-Type Stars
In 1968 van den Heuvel showed that the rotational velocities at many A types have peaks below V sin i = 45 km s⁻¹ and above 90 km s⁻¹. We explored this bimodal behavior by obtaining new rotational velocities of 1761 A-type stars with coudé CCD spectra and, to date, new MK classifications for 956 of...
Guardado en:
| Autores principales: | , |
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| Formato: | Articulo |
| Lenguaje: | Inglés |
| Publicado: |
1993
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| Acceso en línea: | http://sedici.unlp.edu.ar/handle/10915/146382 |
| Aporte de: |
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I19-R120-10915-146382 |
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| 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 Rotational velocities A-type stars |
| spellingShingle |
Ciencias Astronómicas Rotational velocities A-type stars Abt, Helmut A. Morrell, Nidia Irene Rotational Velocities for the Brighter A-Type Stars |
| topic_facet |
Ciencias Astronómicas Rotational velocities A-type stars |
| description |
In 1968 van den Heuvel showed that the rotational velocities at many A types have peaks below V sin i = 45 km s⁻¹ and above 90 km s⁻¹. We explored this bimodal behavior by obtaining new rotational velocities of 1761 A-type stars with coudé CCD spectra and, to date, new MK classifications for 956 of those. We find that the slow rotators consist of Ap, Am, and short-period binaries while the rapid rotators are normal and λ Bootis stars. The overlap is only 8–10% and can probably be attributed to undetected abnormal stars and binaries.
The λ Bootis stars discovered purely by their having weak λ4481 Mg II constitute about 18% of the early A-type stars but 4% at the late ones. Statistically all such λ Bootis stars have V > 100 km s⁻¹ but they constitute only a small fraction of those stars.
More than half of the stars classified as A2 IV (and some at Al IV and A3 IV) seem to be a hitherto unrecognized class of slowly-rotating abnormal-abundance stars of luminosities like those of class V stars. |
| format |
Articulo Articulo |
| author |
Abt, Helmut A. Morrell, Nidia Irene |
| author_facet |
Abt, Helmut A. Morrell, Nidia Irene |
| author_sort |
Abt, Helmut A. |
| title |
Rotational Velocities for the Brighter A-Type Stars |
| title_short |
Rotational Velocities for the Brighter A-Type Stars |
| title_full |
Rotational Velocities for the Brighter A-Type Stars |
| title_fullStr |
Rotational Velocities for the Brighter A-Type Stars |
| title_full_unstemmed |
Rotational Velocities for the Brighter A-Type Stars |
| title_sort |
rotational velocities for the brighter a-type stars |
| publishDate |
1993 |
| url |
http://sedici.unlp.edu.ar/handle/10915/146382 |
| work_keys_str_mv |
AT abthelmuta rotationalvelocitiesforthebrighteratypestars AT morrellnidiairene rotationalvelocitiesforthebrighteratypestars |
| bdutipo_str |
Repositorios |
| _version_ |
1764820461113311234 |