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arXiv · 1712.05939

Detection of a centrifugal magnetosphere in one of the most massive stars in the $ρ$ Oph star-forming cloud

S. Hubrig·M. Schöller·S. P. Järvinen·M. Küker·A. F. Kholtygin·P. Steinbrunner
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Abstract

Recent XMM-Newton observations of the B2 type star rho Oph A indicated a periodicity of 1.205d, which was ascribed to rotational modulation. Since variability of X-ray emission in massive stars is frequently the signature of a magnetic field, we investigated whether the presence of a magnetic field can indeed be invoked to explain the observed X-ray peculiarity. Two FORS2 spectropolarimetric observations in different rotation phases revealed the presence of a negative ( _all=-419+-101G) and positive ( _all=538+-69G) longitudinal magnetic field, respectively. We estimate a lower limit for the dipole strength as B_d = 1.9+-0.2kG. Our calculations of the Kepler and Alfven radii imply the presence of a centrifugally supported, magnetically confined plasma around rho Oph A. The study of the spectral variability indicates a behaviour similar to that observed in typical magnetic early-type Bp stars.

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S. Hubrig, M. Schöller, S. P. Järvinen, M. Küker, A. F. Kholtygin, P. Steinbrunner. 2017-12-16. Detection of a centrifugal magnetosphere in one of the most massive stars in the $ρ$ Oph star-forming cloud. https://doi.org/10.1002/asna.201713457

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