Rotation, spectral variability, magnetic geometry and magnetosphere of the Of?p star CPD -28° 2561
We report magnetic and spectroscopic observations and modelling of the Of?p star CPD-28° 2561. Using more than 75 new spectra, we have measured the equivalent width variations and examined the dynamic spectra of photospheric and wind-sensitive spectral lines. A period search results in an unambiguou...
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| Autores principales: | , , , , , , , , , , , , , , , , , |
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| Formato: | Articulo |
| Lenguaje: | Inglés |
| Publicado: |
2015
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| Acceso en línea: | http://sedici.unlp.edu.ar/handle/10915/86059 |
| Aporte de: |
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I19-R120-10915-86059 |
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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 28° 2561 Stars: individual: CPD Stars: magnetic field Stars: massive Stars: rotation |
| spellingShingle |
Ciencias Astronómicas 28° 2561 Stars: individual: CPD Stars: magnetic field Stars: massive Stars: rotation Wade, G. A. Barbá, Rodolfo Héctor Grunhut, J. Martins, F. Petit, V. Sundqvist, J. O. Townsend, R. H. D. Walborn, N. R. Alecian, E. Alfaro, E. J. Maíz Apellániz, J. Arias, Julia Inés Gamen, Roberto Claudio Morrell, Nidia Irene Nazé, Y. Sota, A. Doula, A. ud MiMeS Collaboration Rotation, spectral variability, magnetic geometry and magnetosphere of the Of?p star CPD -28° 2561 |
| topic_facet |
Ciencias Astronómicas 28° 2561 Stars: individual: CPD Stars: magnetic field Stars: massive Stars: rotation |
| description |
We report magnetic and spectroscopic observations and modelling of the Of?p star CPD-28° 2561. Using more than 75 new spectra, we have measured the equivalent width variations and examined the dynamic spectra of photospheric and wind-sensitive spectral lines. A period search results in an unambiguous 73.41 d variability period. High-resolution spectropolarimetric data analysed using least-squares deconvolution yield a Zeeman signature detected in the mean Stokes V profile corresponding to phase 0.5 of the spectral ephemeris. Interpreting the 73.41 d period as the stellar rotational period, we have phased the equivalent widths and inferred longitudinal field measurements. The phased magnetic data exhibit a weak sinusoidal variation, with maximum of about 565 G at phase 0.5, and a minimum of about -335 G at phase 0.0, with extrema approximately in phase with the (double-wave) Hα equivalent width variation. Modelling of the Hα equivalent width variation assuming a quasi-3D magnetospheric model produces a unique solution for the ambiguous couplet of inclination and magnetic obliquity angles: (i, β) or (β, i) = (35°, 90°). Adopting either geometry, the longitudinal field variation yields a dipole polar intensity B<sub>d</sub> = 2.6 ± 0.9 kG, consistent with that obtained from direct modelling of the Stokes V profiles. We derive a wind magnetic confinement parameter η<sub>*</sub> ≃ 100, leading to an Alfvén radius R<sub>A</sub> ≃ 3-5R<sub>*</sub>, and a Kepler radius R<sub>K</sub> ≃ 20R<sub>*</sub>. This supports a physical scenario in which the Hα emission and other line variability have their origin in an oblique, corotating 'dynamical magnetosphere' structure resulting from a magnetically channelled wind. Nevertheless, the details of the formation of spectral lines and their variability within this framework remain generally poorly understood. |
| format |
Articulo Articulo |
| author |
Wade, G. A. Barbá, Rodolfo Héctor Grunhut, J. Martins, F. Petit, V. Sundqvist, J. O. Townsend, R. H. D. Walborn, N. R. Alecian, E. Alfaro, E. J. Maíz Apellániz, J. Arias, Julia Inés Gamen, Roberto Claudio Morrell, Nidia Irene Nazé, Y. Sota, A. Doula, A. ud MiMeS Collaboration |
| author_facet |
Wade, G. A. Barbá, Rodolfo Héctor Grunhut, J. Martins, F. Petit, V. Sundqvist, J. O. Townsend, R. H. D. Walborn, N. R. Alecian, E. Alfaro, E. J. Maíz Apellániz, J. Arias, Julia Inés Gamen, Roberto Claudio Morrell, Nidia Irene Nazé, Y. Sota, A. Doula, A. ud MiMeS Collaboration |
| author_sort |
Wade, G. A. |
| title |
Rotation, spectral variability, magnetic geometry and magnetosphere of the Of?p star CPD -28° 2561 |
| title_short |
Rotation, spectral variability, magnetic geometry and magnetosphere of the Of?p star CPD -28° 2561 |
| title_full |
Rotation, spectral variability, magnetic geometry and magnetosphere of the Of?p star CPD -28° 2561 |
| title_fullStr |
Rotation, spectral variability, magnetic geometry and magnetosphere of the Of?p star CPD -28° 2561 |
| title_full_unstemmed |
Rotation, spectral variability, magnetic geometry and magnetosphere of the Of?p star CPD -28° 2561 |
| title_sort |
rotation, spectral variability, magnetic geometry and magnetosphere of the of?p star cpd -28° 2561 |
| publishDate |
2015 |
| url |
http://sedici.unlp.edu.ar/handle/10915/86059 |
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Repositorios |
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