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Magnetic geometry a...
Magnetic geometry and surface differential rotation of the bright Am star Alhena A
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- Blazere, Aurore (författare)
- Univ Liege, Inst Astrophys & Geophys, Quartier Agora B5c, Alle 6 Aout 19c, B-4000 Liege, Belgium;Univ Paris Diderot, PSL Univ, Sorbonne Univ, LESIA,Observ Paris,CNRS,Sorbonne Paris Cite, 5 Pl Jules Janssen, F-92195 Meudon, France
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- Petit, Pascal (författare)
- Univ Toulouse, UPS, CNRS, CNES,IRAP, F-31400 Toulouse, France
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- Neiner, Coralie (författare)
- Univ Paris Diderot, PSL Univ, Sorbonne Univ, LESIA,Observ Paris,CNRS,Sorbonne Paris Cite, 5 Pl Jules Janssen, F-92195 Meudon, France
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- Folsom, Colin (författare)
- Univ Toulouse, UPS, CNRS, CNES,IRAP, F-31400 Toulouse, France
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- Kochukhov, Oleg (författare)
- Uppsala universitet,Observationell astrofysik
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- Mathis, Stephane (författare)
- Univ Paris Diderot, PSL Univ, Sorbonne Univ, LESIA,Observ Paris,CNRS,Sorbonne Paris Cite, 5 Pl Jules Janssen, F-92195 Meudon, France;Univ Paris Diderot, IRFU DAp Ctr Saclay, CNRS, Lab AIM Paris Saclay,CEA DRF, F-91191 Gif Sur Yvette, France
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- Deal, Morgan (författare)
- Univ Paris Diderot, PSL Univ, Sorbonne Univ, LESIA,Observ Paris,CNRS,Sorbonne Paris Cite, 5 Pl Jules Janssen, F-92195 Meudon, France
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- Landstreet, John (författare)
- Univ Western Ontario, Dept Phys & Astron, London, ON N6A 3K7, Canada
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(creator_code:org_t)
- 2020-01-13
- 2020
- Engelska.
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Ingår i: Monthly notices of the Royal Astronomical Society. - : OXFORD UNIV PRESS. - 0035-8711 .- 1365-2966. ; 492:4, s. 5794-5810
- Relaterad länk:
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https://academic.oup...
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https://urn.kb.se/re...
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https://doi.org/10.1...
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Abstract
Ämnesord
Stäng
- Alhena A (y Gem A) is a bright Am star, with the strongest disc -integrated magnetic field strength reported so far for an Am star. Its spectrum exhibits standard circularly polarized Zeeman signatures, contrary to all previously studied Am stars that display abnormal signatures dominated by a single -signed lobe. We present here the result of follow-up observations of Athena, using very high signal-to-noise spectropolarimetric data obtained over 25 observing nights with NARVAL at Telescope Bernard Lyot, in the frame of the BRITE (BRIght Target Explorer) spectropolarimetric survey. We confirm that Alhena A is magnetic and we determine its surface magnetic properties using different methods. Inclined dipole models are used to reproduce the longitudinal field measurements, as well as the Stokes V line profiles themselves. In both cases, the model is consistent with a polar field strength of 30 G. This is confirmed by a Zeeman -Doppler Imaging (ZDI) model, which also unveils smaller scale magnetic structures. A rotational period of 8.975 d was identified using intensity line profile variations. The ZDI inversion suggests that the surface magnetic field is sheared by differential rotation, with a difference in rotation rate between high and low latitudes at about 15 per cent of the solar value. This result challenges theories of the development of surface differential rotation in intermediate mass main -sequence stars.
Ämnesord
- NATURVETENSKAP -- Fysik -- Astronomi, astrofysik och kosmologi (hsv//swe)
- NATURAL SCIENCES -- Physical Sciences -- Astronomy, Astrophysics and Cosmology (hsv//eng)
Nyckelord
- stars: binaries
- stars: chemically peculiar
- s s e ly-type -s s: individual: Alhena-stars: magnetic field
Publikations- och innehållstyp
- ref (ämneskategori)
- art (ämneskategori)
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