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The Detection of Variable Radio Emission from the Fast Rotating Magnetic Hot B-Star HR 7355 and Evidence for Its X-Ray Aurorae

In this paper we investigate the multiwavelengths properties of the magnetic early B-type star HR7355. We present its radio light curves at several frequencies, taken with the Jansky Very Large Array, and X-ray spectra, taken with the XMM X-ray telescope. Modeling of the radio light curves for the Stokes I and V provides a quantitative analysis of the HR7355 magnetosphere. A comparison between HR7355 and a similar analysis for the Ap star CUVir, allows us to study how the different physical parameters of the two stars affect the structure of the respective magnetospheres where the non-thermal electrons originate. Our model includes a cold thermal plasma component that accumulates at high magnetic latitudes that influences the radio regime, but does not give rise to X-ray emission. Instead, the thermal X-ray emission arises from shocks generated by wind stream collisions close to the magnetic equatorial plane. The analysis of the X-ray spectrum of HR7355 also suggests the presence of a non-thermal radiation. Comparison between the spectral index of the power-law X-ray energy distribution with the non-thermal electron energy distribution indicates that the non-thermal X-ray component could be the auroral signature of the non-thermal electrons that impact the stellar surface, the same non-thermal electrons that are responsible for the observed radio emission. On the basis of our analysis, we suggest a novel model that simultaneously explains the X-ray and the radio features of HR7355 and is likely relevant for magnetospheres of other magnetic early type stars.

Identiferoai:union.ndltd.org:ETSU/oai:dc.etsu.edu:etsu-works-3794
Date01 June 2017
CreatorsLeto, P., Trigilio, Corrado, Oskinova, Lidia M., Ignace, Richard, Buemi, C. S., Umana, G., Ingallinera, A., Todt, H., Leone, F.
PublisherDigital Commons @ East Tennessee State University
Source SetsEast Tennessee State University
Detected LanguageEnglish
Typetext
SourceETSU Faculty Works

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