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How dusty is alpha ...
How dusty is alpha Centauri? : Excess or non-excess over the infrared photospheres of main-sequence stars
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- Wiegert, Joachim, 1985 (författare)
- Chalmers tekniska högskola,Chalmers University of Technology
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- Liseau, René, 1949 (författare)
- Chalmers tekniska högskola,Chalmers University of Technology
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- Thebault, P. (författare)
- Observatoire de Paris-Meudon
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- Olofsson, Göran (författare)
- Stockholms universitet,Institutionen för astronomi,Stockholm University
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- Mora, A. (författare)
- European Space Astronomy Centre (ESAC)
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Bryden, G. (författare)
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- Marshall, J. P. (författare)
- Universidad Autonoma de Madrid (UAM)
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- Eiroa, C. (författare)
- Universidad Autonoma de Madrid (UAM)
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- Montesinos, B. (författare)
- Centro de Astrobiologia (CAB)
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- Ardila, D. (författare)
- European Space Astronomy Centre (ESAC),California Institute of Technology (Caltech)
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- Augereau, J. C. (författare)
- Université Grenoble Alpes,Grenoble Alpes University
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- Aran, A. Bayo (författare)
- Max Planck Gesellschaft zur Förderung der Wissenschaften e.V. (MPG),Max Planck Society for the Advancement of Science (MPG),European Southern Observatory Santiago
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- Danchi, W. C. (författare)
- NASA Goddard Space Flight Center
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- del Burgo, C. (författare)
- Instituto Nacional de Astrofísica, Óptica y Electrońica (INAOE),National Institute of Astrophysics, Optics and Electronics (INAOE)
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- Ertel, S. (författare)
- Université Grenoble Alpes,Grenoble Alpes University
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- Fridlund, M. C. W. (författare)
- Deutsches Zentrums für Luft- und Raumfahrt (DLR),German Aerospace Center (DLR),Universiteit Leiden (UL),Leiden University (UL)
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- Hajigholi, Mitra, 1986 (författare)
- Chalmers tekniska högskola,Chalmers University of Technology
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- Krivov, A. V. (författare)
- Friedrich-Schiller-Universität Jena,Friedrich Schiller University Jena
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- Pilbratt, G. L. (författare)
- European Space Research and Technology Centre (ESA ESTEC)
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- Roberge, A. (författare)
- NASA Goddard Space Flight Center
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- White, G. J. (författare)
- Open University,STFC Rutherford Appleton Laboratory
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- Wolf, S. (författare)
- Christian-Albrechts-Universität zu Kiel,University of Kiel
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(creator_code:org_t)
- 2014-03-17
- 2014
- Engelska.
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 563, s. A102-
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Abstract
Ämnesord
Stäng
- Context. Debris discs around main-sequence stars indicate the presence of larger rocky bodies. The components of the nearby, solar-type binary alpha Centauri have metallicities that are higher than solar, which is thought to promote giant planet formation. Aims. We aim to determine the level of emission from debris around the stars in the alpha Cen system. This requires knowledge of their photospheres. Having already detected the temperature minimum, T-min, of alpha Cen A at far-infrared wavelengths, we here attempt to do the same for the more active companion alpha Cen B. Using the alpha Cen stars as templates, we study the possible effects that T-min may have on the detectability of unresolved dust discs around other stars. Methods. We used Herschel-PACS, Herschel-SPIRE, and APEX-LABOCA photometry to determine the stellar spectral energy distributions in the far infrared and submillimetre. In addition, we used APEX-SHeFI observations for spectral line mapping to study the complex background around alpha Cen seen in the photometric images. Models of stellar atmospheres and of particulate discs, based on particle simulations and in conjunction with radiative transfer calculations, were used to estimate the amount of debris around these stars. Results. For solar-type stars more distant than alpha Cen, a fractional dust luminosity f(d) equivalent to L-dust/L-star similar to 2 x 10(-7) could account for SEDs that do not exhibit the T-min effect. This is comparable to estimates of f(d) for the Edgeworth-Kuiper belt of the solar system. In contrast to the far infrared, slight excesses at the 2.5 sigma level are observed at 24 mu m for both alpha Cen A and B, which, if interpreted as due to zodiacal-type dust emission, would correspond to f(d) similar to (1-3) x 10(-5), i.e. some 10(2) times that of the local zodiacal cloud. Assuming simple power-law size distributions of the dust grains, dynamical disc modelling leads to rough mass estimates of the putative Zodi belts around the alpha Cen stars, viz. less than or similar to 4 x 10(-6) M-(sic) of 4 to 1000 mu m size grains, distributed according to n(a) proportional to a(-3.5). Similarly, for filled-in T-min emission, corresponding Edgeworth-Kuiper belts could account for similar to 10(-3) M-(sic) of dust. Conclusions. Our far-infrared observations lead to estimates of upper limits to the amount of circumstellar dust around the stars alpha Cen A and B. Light scattered and/or thermally emitted by exo-Zodi discs will have profound implications for future spectroscopic missions designed to search for biomarkers in the atmospheres of Earth-like planets. The far-infrared spectral energy distribution of alpha Cen B is marginally consistent with the presence of a minimum temperature region in the upper atmosphere of the star. We also show that an alpha Cen A-like temperature minimum may result in an erroneous apprehension about the presence of dust around other, more distant stars.
Ämnesord
- NATURVETENSKAP -- Fysik -- Astronomi, astrofysik och kosmologi (hsv//swe)
- NATURAL SCIENCES -- Physical Sciences -- Astronomy, Astrophysics and Cosmology (hsv//eng)
Nyckelord
- stars: individual: Alpha Centauri
- binaries: general
- circumstellar matter
- infrared: stars
- infrared: planetary systems
- submillimeter: stars
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- art (ämneskategori)
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Wiegert, Joachim ...
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Liseau, René, 19 ...
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Thebault, P.
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Olofsson, Göran
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Mora, A.
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Bryden, G.
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visa fler...
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Marshall, J. P.
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Eiroa, C.
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Montesinos, B.
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Ardila, D.
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Augereau, J. C.
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Aran, A. Bayo
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Danchi, W. C.
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del Burgo, C.
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Ertel, S.
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Fridlund, M. C. ...
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Hajigholi, Mitra ...
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Krivov, A. V.
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Pilbratt, G. L.
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Roberge, A.
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White, G. J.
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Wolf, S.
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