Critical study of the distribution of rotational velocities of Be stars : II: Differential rotation and some hidden effects interfering with the interpretation of the V sin i param...
- Autores
- Zorec, Juan; Frémat, Y.; Domiciano de Souza, A.; Royer, F.; Cidale, Lydia Sonia; Hubert, A. M.; Semaan, T.; Martayan, C.; Cochetti, Yanina Roxana; Arias, María Laura; Aidelman, Yael Judith; Stee, P.
- Año de publicación
- 2017
- Idioma
- inglés
- Tipo de recurso
- artículo
- Estado
- versión publicada
- Descripción
- Aims. We assume that stars may undergo surface differential rotation to study its impact on the interpretation of Vsin i and on the observed distribution Φ(u) of ratios of true rotational velocities u = V/Vc (Vc is the equatorial critical velocity). We discuss some phenomena affecting the formation of spectral lines and their broadening, which can obliterate the information carried by Vsin i concerning the actual stellar rotation. Methods. We studied the line broadening produced by several differential rotational laws, but adopted Maunder's expression Ω(0) = Ω0(1 + α cos2 0) as an attempt to account for all of these laws with the lowest possible number of free parameters. We studied the effect of the differential rotation parameter a on the measured Vsin i parameter and on the distribution Φ(u) of ratios u = V/Vc. Results. We conclude that the inferred Vsin i is smaller than implied by the actual equatorial linear rotation velocity Veq if the stars rotate with α < 0, but is larger if the stars have a α > 0. For a given |α| the deviations of Vsin i are larger when α < 0. If the studied Be stars have on average α < 0, the number of rotators with Veq 0.9Vc is larger than expected from the observed distribution Φ(u); if these stars have on average α > 0, this number is lower than expected. We discuss seven phenomena that contribute either to narrow or broaden spectral lines, which blur the information on the rotation carried by Vsin i and, in particular, to decide whether the Be phenomenon mostly rely on the critical rotation. We show that two-dimensional radiation transfer calculations are needed in rapid rotators to diagnose the stellar rotation more reliably.
Facultad de Ciencias Astronómicas y Geofísicas - Materia
-
Astronomía
stars: emission-line
Be - stars: rotation - Nivel de accesibilidad
- acceso abierto
- Condiciones de uso
- http://creativecommons.org/licenses/by-nc-sa/4.0/
- Repositorio
- Institución
- Universidad Nacional de La Plata
- OAI Identificador
- oai:sedici.unlp.edu.ar:10915/77716
Ver los metadatos del registro completo
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Critical study of the distribution of rotational velocities of Be stars : II: Differential rotation and some hidden effects interfering with the interpretation of the V sin i parameterZorec, JuanFrémat, Y.Domiciano de Souza, A.Royer, F.Cidale, Lydia SoniaHubert, A. M.Semaan, T.Martayan, C.Cochetti, Yanina RoxanaArias, María LauraAidelman, Yael JudithStee, P.Astronomíastars: emission-lineBe - stars: rotationAims. We assume that stars may undergo surface differential rotation to study its impact on the interpretation of Vsin i and on the observed distribution Φ(u) of ratios of true rotational velocities u = V/Vc (Vc is the equatorial critical velocity). We discuss some phenomena affecting the formation of spectral lines and their broadening, which can obliterate the information carried by Vsin i concerning the actual stellar rotation. Methods. We studied the line broadening produced by several differential rotational laws, but adopted Maunder's expression Ω(0) = Ω0(1 + α cos2 0) as an attempt to account for all of these laws with the lowest possible number of free parameters. We studied the effect of the differential rotation parameter a on the measured Vsin i parameter and on the distribution Φ(u) of ratios u = V/Vc. Results. We conclude that the inferred Vsin i is smaller than implied by the actual equatorial linear rotation velocity Veq if the stars rotate with α < 0, but is larger if the stars have a α > 0. For a given |α| the deviations of Vsin i are larger when α < 0. If the studied Be stars have on average α < 0, the number of rotators with Veq 0.9Vc is larger than expected from the observed distribution Φ(u); if these stars have on average α > 0, this number is lower than expected. We discuss seven phenomena that contribute either to narrow or broaden spectral lines, which blur the information on the rotation carried by Vsin i and, in particular, to decide whether the Be phenomenon mostly rely on the critical rotation. We show that two-dimensional radiation transfer calculations are needed in rapid rotators to diagnose the stellar rotation more reliably.Facultad de Ciencias Astronómicas y Geofísicas2017-06info:eu-repo/semantics/articleinfo:eu-repo/semantics/publishedVersionArticulohttp://purl.org/coar/resource_type/c_6501info:ar-repo/semantics/articuloapplication/pdfhttp://sedici.unlp.edu.ar/handle/10915/77716enginfo:eu-repo/semantics/altIdentifier/issn/1432-0746info:eu-repo/semantics/altIdentifier/doi/10.1051/0004-6361/201628761info:eu-repo/semantics/openAccesshttp://creativecommons.org/licenses/by-nc-sa/4.0/Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International (CC BY-NC-SA 4.0)reponame:SEDICI (UNLP)instname:Universidad Nacional de La Platainstacron:UNLP2025-10-15T11:05:50Zoai:sedici.unlp.edu.ar:10915/77716Institucionalhttp://sedici.unlp.edu.ar/Universidad públicaNo correspondehttp://sedici.unlp.edu.ar/oai/snrdalira@sedici.unlp.edu.arArgentinaNo correspondeNo correspondeNo correspondeopendoar:13292025-10-15 11:05:50.863SEDICI (UNLP) - Universidad Nacional de La Platafalse |
dc.title.none.fl_str_mv |
Critical study of the distribution of rotational velocities of Be stars : II: Differential rotation and some hidden effects interfering with the interpretation of the V sin i parameter |
title |
Critical study of the distribution of rotational velocities of Be stars : II: Differential rotation and some hidden effects interfering with the interpretation of the V sin i parameter |
spellingShingle |
Critical study of the distribution of rotational velocities of Be stars : II: Differential rotation and some hidden effects interfering with the interpretation of the V sin i parameter Zorec, Juan Astronomía stars: emission-line Be - stars: rotation |
title_short |
Critical study of the distribution of rotational velocities of Be stars : II: Differential rotation and some hidden effects interfering with the interpretation of the V sin i parameter |
title_full |
Critical study of the distribution of rotational velocities of Be stars : II: Differential rotation and some hidden effects interfering with the interpretation of the V sin i parameter |
title_fullStr |
Critical study of the distribution of rotational velocities of Be stars : II: Differential rotation and some hidden effects interfering with the interpretation of the V sin i parameter |
title_full_unstemmed |
Critical study of the distribution of rotational velocities of Be stars : II: Differential rotation and some hidden effects interfering with the interpretation of the V sin i parameter |
title_sort |
Critical study of the distribution of rotational velocities of Be stars : II: Differential rotation and some hidden effects interfering with the interpretation of the V sin i parameter |
dc.creator.none.fl_str_mv |
Zorec, Juan Frémat, Y. Domiciano de Souza, A. Royer, F. Cidale, Lydia Sonia Hubert, A. M. Semaan, T. Martayan, C. Cochetti, Yanina Roxana Arias, María Laura Aidelman, Yael Judith Stee, P. |
author |
Zorec, Juan |
author_facet |
Zorec, Juan Frémat, Y. Domiciano de Souza, A. Royer, F. Cidale, Lydia Sonia Hubert, A. M. Semaan, T. Martayan, C. Cochetti, Yanina Roxana Arias, María Laura Aidelman, Yael Judith Stee, P. |
author_role |
author |
author2 |
Frémat, Y. Domiciano de Souza, A. Royer, F. Cidale, Lydia Sonia Hubert, A. M. Semaan, T. Martayan, C. Cochetti, Yanina Roxana Arias, María Laura Aidelman, Yael Judith Stee, P. |
author2_role |
author author author author author author author author author author author |
dc.subject.none.fl_str_mv |
Astronomía stars: emission-line Be - stars: rotation |
topic |
Astronomía stars: emission-line Be - stars: rotation |
dc.description.none.fl_txt_mv |
Aims. We assume that stars may undergo surface differential rotation to study its impact on the interpretation of Vsin i and on the observed distribution Φ(u) of ratios of true rotational velocities u = V/Vc (Vc is the equatorial critical velocity). We discuss some phenomena affecting the formation of spectral lines and their broadening, which can obliterate the information carried by Vsin i concerning the actual stellar rotation. Methods. We studied the line broadening produced by several differential rotational laws, but adopted Maunder's expression Ω(0) = Ω0(1 + α cos2 0) as an attempt to account for all of these laws with the lowest possible number of free parameters. We studied the effect of the differential rotation parameter a on the measured Vsin i parameter and on the distribution Φ(u) of ratios u = V/Vc. Results. We conclude that the inferred Vsin i is smaller than implied by the actual equatorial linear rotation velocity Veq if the stars rotate with α < 0, but is larger if the stars have a α > 0. For a given |α| the deviations of Vsin i are larger when α < 0. If the studied Be stars have on average α < 0, the number of rotators with Veq 0.9Vc is larger than expected from the observed distribution Φ(u); if these stars have on average α > 0, this number is lower than expected. We discuss seven phenomena that contribute either to narrow or broaden spectral lines, which blur the information on the rotation carried by Vsin i and, in particular, to decide whether the Be phenomenon mostly rely on the critical rotation. We show that two-dimensional radiation transfer calculations are needed in rapid rotators to diagnose the stellar rotation more reliably. Facultad de Ciencias Astronómicas y Geofísicas |
description |
Aims. We assume that stars may undergo surface differential rotation to study its impact on the interpretation of Vsin i and on the observed distribution Φ(u) of ratios of true rotational velocities u = V/Vc (Vc is the equatorial critical velocity). We discuss some phenomena affecting the formation of spectral lines and their broadening, which can obliterate the information carried by Vsin i concerning the actual stellar rotation. Methods. We studied the line broadening produced by several differential rotational laws, but adopted Maunder's expression Ω(0) = Ω0(1 + α cos2 0) as an attempt to account for all of these laws with the lowest possible number of free parameters. We studied the effect of the differential rotation parameter a on the measured Vsin i parameter and on the distribution Φ(u) of ratios u = V/Vc. Results. We conclude that the inferred Vsin i is smaller than implied by the actual equatorial linear rotation velocity Veq if the stars rotate with α < 0, but is larger if the stars have a α > 0. For a given |α| the deviations of Vsin i are larger when α < 0. If the studied Be stars have on average α < 0, the number of rotators with Veq 0.9Vc is larger than expected from the observed distribution Φ(u); if these stars have on average α > 0, this number is lower than expected. We discuss seven phenomena that contribute either to narrow or broaden spectral lines, which blur the information on the rotation carried by Vsin i and, in particular, to decide whether the Be phenomenon mostly rely on the critical rotation. We show that two-dimensional radiation transfer calculations are needed in rapid rotators to diagnose the stellar rotation more reliably. |
publishDate |
2017 |
dc.date.none.fl_str_mv |
2017-06 |
dc.type.none.fl_str_mv |
info:eu-repo/semantics/article info:eu-repo/semantics/publishedVersion Articulo 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://sedici.unlp.edu.ar/handle/10915/77716 |
url |
http://sedici.unlp.edu.ar/handle/10915/77716 |
dc.language.none.fl_str_mv |
eng |
language |
eng |
dc.relation.none.fl_str_mv |
info:eu-repo/semantics/altIdentifier/issn/1432-0746 info:eu-repo/semantics/altIdentifier/doi/10.1051/0004-6361/201628761 |
dc.rights.none.fl_str_mv |
info:eu-repo/semantics/openAccess http://creativecommons.org/licenses/by-nc-sa/4.0/ Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International (CC BY-NC-SA 4.0) |
eu_rights_str_mv |
openAccess |
rights_invalid_str_mv |
http://creativecommons.org/licenses/by-nc-sa/4.0/ Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International (CC BY-NC-SA 4.0) |
dc.format.none.fl_str_mv |
application/pdf |
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SEDICI (UNLP) |
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Universidad Nacional de La Plata |
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UNLP |
repository.name.fl_str_mv |
SEDICI (UNLP) - Universidad Nacional de La Plata |
repository.mail.fl_str_mv |
alira@sedici.unlp.edu.ar |
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