Magnetic field detection in the B2 Vn star HR 7355★
| Autor: | Richard H. D. Townsend, Th. Rivinius, L. Barrera, S. Štefl, Th. Szeifert, Dietrich Baade |
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| Rok vydání: | 2010 |
| Předmět: |
Physics
Field (physics) Astronomy and Astrophysics Astrophysics::Cosmology and Extragalactic Astrophysics Astrophysics Star (graph theory) Spectral line Magnetic field Dipole Stars Amplitude Space and Planetary Science Astrophysics::Solar and Stellar Astrophysics Astrophysics::Earth and Planetary Astrophysics Equivalent width Astrophysics::Galaxy Astrophysics |
| Zdroj: | Monthly Notices of the Royal Astronomical Society: Letters. 405:L46-L50 |
| ISSN: | 1745-3933 1745-3925 |
| DOI: | 10.1111/j.1745-3933.2010.00856.x |
| Popis: | The B2Vn star HR 7355 is found to be a He-rich magnetic star. Spectropolarimetric data were obtained with FORS1 at UT2 on Paranal observatory to measure the disk-averaged longitudinal magnetic field at various phases of the presumed 0.52 d cycle. A variable magnetic field with strengths between B_z = -2200 and +3200G was found, with confidence limits of 100 to 130G. The field topology is that of an oblique dipole, while the star itself is seen about equator-on. In the intensity spectra the HeI-lines show the typical equivalent width variability of He-strong stars, usually attributed to surface abundance spots. The amplitudes of the equivalent width variability of the HeI lines are extraordinarily strong compared to other cases. These results not only put HR 7355 unambiguously among the early-type magnetic stars, but confirm its outstanding nature: With v sin i = 320 km/s the parameter space in which He-strong stars are known to exist has doubled in terms of rotational velocity. |
| Databáze: | OpenAIRE |
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