Paolo Leto, C. Trigilio, Lidia M. Oskinova, R. Ignace, C. S. Buemi, G. Umana, A. Ingallinera, Francesco Leone, N. M. Phillips, Claudia Agliozzo, Helge Tobias Todt, L. Cerrigone
- We present new radio/millimeter measurements of the hot magnetic star HR5907 obtained with the VLA and ALMA interferometers. We find that HR5907 is the most radio luminous early type star in the cm-mm band among those presently known. Its multi-wavelength radio light curves are strongly variable with an amplitude that increases with radio frequency. The radio emission can be explained by the populations of the non-thermal electrons accelerated in the current sheets on the outer border of the magnetosphere of this fast-rotating magnetic star. We classify HR5907 as another member of the growing class of strongly magnetic fast-rotating hot stars where the gyro-synchrotron emission mechanism efficiently operates in their magnetospheres. The new radio observations of HR5907 are combined with archival X-ray data to study the physical condition of its magnetosphere. The X-ray spectra of HR5907 show tentative evidence for the presence of non-thermal spectral component. We suggest that non-thermal X-rays originate a stellar X-ray aurora due toWe present new radio/millimeter measurements of the hot magnetic star HR5907 obtained with the VLA and ALMA interferometers. We find that HR5907 is the most radio luminous early type star in the cm-mm band among those presently known. Its multi-wavelength radio light curves are strongly variable with an amplitude that increases with radio frequency. The radio emission can be explained by the populations of the non-thermal electrons accelerated in the current sheets on the outer border of the magnetosphere of this fast-rotating magnetic star. We classify HR5907 as another member of the growing class of strongly magnetic fast-rotating hot stars where the gyro-synchrotron emission mechanism efficiently operates in their magnetospheres. The new radio observations of HR5907 are combined with archival X-ray data to study the physical condition of its magnetosphere. The X-ray spectra of HR5907 show tentative evidence for the presence of non-thermal spectral component. We suggest that non-thermal X-rays originate a stellar X-ray aurora due to streams of non-thermal electrons impacting on the stellar surface. Taking advantage of the relation between the spectral indices of the X-ray power-law spectrum and the non-thermal electron energy distributions, we perform 3-D modelling of the radio emission for HR5907. The wavelength-dependent radio light curves probe magnetospheric layers at different heights above the stellar surface. A detailed comparison between simulated and observed radio light curves leads us to conclude that the stellar magnetic field of HR 5907 is likely non-dipolar, providing further indirect evidence of the complex magnetic field topology of HR5907.…
MetadatenAuthor details: | Paolo LetoORCiD, C. Trigilio, Lidia M. OskinovaORCiDGND, R. Ignace, C. S. Buemi, G. Umana, A. Ingallinera, Francesco LeoneORCiD, N. M. Phillips, Claudia AgliozzoORCiD, Helge Tobias TodtORCiD, L. Cerrigone |
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DOI: | https://doi.org/10.1093/mnras/sty244 |
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ISSN: | 0035-8711 |
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ISSN: | 1365-2966 |
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Title of parent work (English): | Monthly notices of the Royal Astronomical Society |
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Publisher: | Oxford Univ. Press |
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Place of publishing: | Oxford |
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Publication type: | Article |
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Language: | English |
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Date of first publication: | 2018/01/31 |
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Publication year: | 2018 |
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Release date: | 2021/12/07 |
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Tag: | X-rays: stars; radio continuum: stars; stars: chemically peculiar; stars: early-type; stars: individual: HR 5907; stars: magnetic field |
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Volume: | 476 |
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Issue: | 1 |
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Number of pages: | 18 |
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First page: | 562 |
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Last Page: | 579 |
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Funding institution: | DLR grantHelmholtz AssociationGerman Aerospace Centre (DLR) [50OR1508] |
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Organizational units: | Mathematisch-Naturwissenschaftliche Fakultät / Institut für Physik und Astronomie |
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DDC classification: | 5 Naturwissenschaften und Mathematik / 53 Physik / 530 Physik |
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Peer review: | Referiert |
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Publishing method: | Open Access / Green Open-Access |
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