| dc.creator | Zorec, Juan | |
| dc.creator | Frémat, Y. | |
| dc.creator | Domiciano de Souza, A. | |
| dc.creator | Royer, F. | |
| dc.creator | Cidale, Lydia Sonia | |
| dc.creator | Hubert, A. M. | |
| dc.creator | Semaan, T. | |
| dc.creator | Martayan, C. | |
| dc.creator | Cochetti, Yanina Roxana | |
| dc.creator | Arias, María Laura | |
| dc.creator | Aidelman, Yael Judith | |
| dc.creator | Stee, P. | |
| dc.date | 2017-06 | |
| dc.date | 2019-07-04T17:57:10Z | |
| dc.identifier | http://sedici.unlp.edu.ar/handle/10915/77716 | |
| dc.identifier | issn:1432-0746 | |
| dc.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. | |
| dc.description | Facultad de Ciencias Astronómicas y Geofísicas | |
| dc.format | application/pdf | |
| dc.language | en | |
| dc.rights | http://creativecommons.org/licenses/by-nc-sa/4.0/ | |
| dc.rights | Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International (CC BY-NC-SA 4.0) | |
| dc.subject | Astronomía | |
| dc.subject | stars: emission-line | |
| dc.subject | Be - stars: rotation | |
| dc.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 | |
| dc.type | Articulo | |
| dc.type | Articulo | |
