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Large granulation c...
Large granulation cells on the surface of the giant star π1 Gruis
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- Paladini, C. (författare)
- Univ Libre Bruxelles, Inst Astron & Astrophys, CP 226, B-1050 Brussels, Belgium.;European Southern Observ, Alonso de Cordova 3107, Santiago, Chile., Chile.
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- Baron, F. (författare)
- Georgia State Univ, Dept Phys & Astron, POB 5060, Atlanta, GA 30302 USA.
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- Jorissen, A. (författare)
- Univ Libre Bruxelles, Inst Astron & Astrophys, CP 226, B-1050 Brussels, Belgium.
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- Le Bouquin, J. -B (författare)
- Univ Grenoble Alpes, CNRS, IPAG, F-38000 Grenoble, France.
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- Freytag, Bernd (författare)
- Uppsala universitet,Teoretisk astrofysik
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- Van Eck, S. (författare)
- Univ Libre Bruxelles, Inst Astron & Astrophys, CP 226, B-1050 Brussels, Belgium.
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- Wittkowski, M. (författare)
- European Southern Observ, Karl Schwarzschild Str 2, D-85748 Garching, Germany.
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- Hron, J. (författare)
- Univ Vienna, Dept Astrophys, Turkenschanzstr 17, A-1180 Vienna, Austria.
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- Chiavassa, A. (författare)
- Univ Nice Sophia Antipolis, Lab Lagrange, Observ Cote Azur, UMR 7293,CNRS, BP 4229, F-06304 Nice 4, France.
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Berger, J. -P (författare)
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- Siopis, C. (författare)
- Univ Libre Bruxelles, Inst Astron & Astrophys, CP 226, B-1050 Brussels, Belgium.
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- Mayer, A. (författare)
- Univ Vienna, Dept Astrophys, Turkenschanzstr 17, A-1180 Vienna, Austria.
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- Sadowski, G. (författare)
- Univ Libre Bruxelles, Inst Astron & Astrophys, CP 226, B-1050 Brussels, Belgium.
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- Kravchenko, K. (författare)
- Univ Libre Bruxelles, Inst Astron & Astrophys, CP 226, B-1050 Brussels, Belgium.
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- Shetye, S. (författare)
- Univ Libre Bruxelles, Inst Astron & Astrophys, CP 226, B-1050 Brussels, Belgium.
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- Kerschbaum, F. (författare)
- Univ Vienna, Dept Astrophys, Turkenschanzstr 17, A-1180 Vienna, Austria.
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- Kluska, J. (författare)
- Univ Exeter, Dept Phys & Astron, Stocker Rd, Exeter EX4 4QL, Devon, England.
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- Ramstedt, Sofia (författare)
- Uppsala universitet,Teoretisk astrofysik
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Univ Libre Bruxelles, Inst Astron & Astrophys, CP 226, B-1050 Brussels, Belgium;European Southern Observ, Alonso de Cordova 3107, Santiago, Chile., Chile. Georgia State Univ, Dept Phys & Astron, POB 5060, Atlanta, GA 30302 USA. (creator_code:org_t)
- 2017-12-20
- 2018
- Engelska.
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 553:7688, s. 310-
- Relaterad länk:
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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
- Convection plays a major part in many astrophysical processes, including energy transport, pulsation, dynamos and winds on evolved stars, in dust clouds and on brown dwarfs1,2. Most of our knowledge about stellar convection has come from studying the Sun: about two million convective cells with typical sizes of around 2,000 kilometres across are present on the surface of the Sun3—a phenomenon known as granulation. But on the surfaces of giant and supergiant stars there should be only a few large (several tens of thousands of times larger than those on the Sun) convective cells3, owing to low surface gravity. Deriving the characteristic properties of convection (such as granule size and contrast) for the most evolved giant and supergiant stars is challenging because their photospheres are obscured by dust, which partially masks the convective patterns4. These properties can be inferred from geometric model fitting5,6,7, but this indirect method does not provide information about the physical origin of the convective cells5,6,7. Here we report interferometric images of the surface of the evolved giant star π1 Gruis, of spectral type8,9 S5,7. Our images show a nearly circular, dust-free atmosphere, which is very compact and only weakly affected by molecular opacity. We find that the stellar surface has a complex convective pattern with an average intensity contrast of 12 per cent, which increases towards shorter wavelengths. We derive a characteristic horizontal granule size of about 1.2 × 1011 metres, which corresponds to 27 per cent of the diameter of the star. Our measurements fall along the scaling relations between granule size, effective temperature and surface gravity that are predicted by simulations of stellar surface convection10,11,12.
Ämnesord
- NATURVETENSKAP -- Fysik -- Astronomi, astrofysik och kosmologi (hsv//swe)
- NATURAL SCIENCES -- Physical Sciences -- Astronomy, Astrophysics and Cosmology (hsv//eng)
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Paladini, C.
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Baron, F.
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Jorissen, A.
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Le Bouquin, J. - ...
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Freytag, Bernd
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Van Eck, S.
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visa fler...
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Wittkowski, M.
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Hron, J.
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Chiavassa, A.
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Berger, J. -P
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Siopis, C.
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Mayer, A.
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Sadowski, G.
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Kravchenko, K.
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Shetye, S.
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Kerschbaum, F.
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Kluska, J.
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Ramstedt, Sofia
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