$α$ Centauri A in the far infrared

Дата и время публикации : 2012-12-17T10:33:41Z

Авторы публикации и институты :
R. Liseau (Department of Earth and Space Sciences, Chalmers University of Technology, Onsala Space Observatory, Onsala, Sweden)
B. Montesinos (Departamento de Astrofísica, Centro de Astrobiología)
G. Olofsson (Department of Astronomy, Stockholm University, Stockholm, Sweden)
G. Bryden (Jet Propulsion Laboratory, Pasadena, CA, USA)
J. P. Marshall (Departamento de Física Teórica, C-XI, Facultad de Ciencias, Universidad Autónoma de Madrid, Madrid, Spain)
D. Ardila (NASA Herschel Science Center, Infrared Processing and Analysis Center, California Institute of Technology, Pasadena, CA, USA, Herschel Science Center, European Space Agency)
A. Bayo Aran (European Southern Observatory, Santiago, Chile, Max Planck Institut für Astronomie, Heidelberg, Germany)
W. C. Danchi (Astrophysics Science Division, NASA Goddard Space Flight Center, Greenbelt, MD, USA)
C. del Burgo (Instituto Nacional de Astrofísica, Óptica y Electrónica)
C. Eiroa (Departamento de Física Teórica, C-XI, Facultad de Ciencias, Universidad Autónoma de Madrid, Madrid, Spain)
S. Ertel (UJF-Grenoble 1, CNRS-INSU, Institut de Planétologie et d’Astrophysique de Grenoble)
M. C. W. Fridlund (Astrophysics Mission Division, Research and Scientific Support Department ESA, ESTEC, Noordwijk, The Netherlands)
A. V. Krivov (Astrophysikalisches Institut und Universitätssternwarte, Friedrich-Schiller-Universität Jena, Jena, Germany)
G. L. Pilbratt (Astrophysics Mission Division, Research and Scientific Support Department ESA, ESTEC, Noordwijk, The Netherlands)
A. Roberge (NASA Goddard Space Flight Center, Exoplanets and Stellar Astrophysics Laboratory, Greenbelt, MD, USA)
P. Thébault (Observatoire de Paris, Section de Meudon 5, Meudon, Laboratoire d’études spatiales et d’instrumentation en astrophysique, France)
J. Wiegert (Department of Earth and Space Sciences, Chalmers University of Technology, Onsala Space Observatory, Onsala, Sweden)
G. J. White (Dept. of Physics and Astronomy, The Open University, Milton Keynes, UK, Space Science and Technology Department, CCLRC Rutherford Appleton Laboratory, Oxfordshire, UK)

Ссылка на журнал-издание: Ссылка на журнал-издание не найдена
Коментарии к cтатье: 5 pages, 1 figure, A&A Letters, in press
Первичная категория: astro-ph.SR

Все категории : astro-ph.SR

Краткий обзор статьи: Chromospheres and coronae are common phenomena on solar-type stars. Understanding the energy transfer to these heated atmospheric layers requires direct access to the relevant empirical data. Study of these structures has, by and large, been limited to the Sun thus far. The region of the temperature reversal can be directly observed only in the far infrared and submm. We aim at the determination of the characteristics of the atmosphere in the region of the temperature minimum of the solar sister star alpha Cen A. For the nearby binary system alpha Centauri, stellar parameters are known with high accuracy from measurements. For the basic model parameters Teff, log g and [Fe/H], we interpolate in the grid of GAIA/PHOENIX stellar model atmospheres and compute the corresponding model for the G2 V star alpha Cen A. Comparison with photometric measurements shows excellent agreement between observed photospheric data in the optical and infrared. For longer wavelengths, the modelled spectral energy distribution is compared to MIPS, PACS, SPIRE and LABOCA photometry. A specifically tailored Uppsala model based on the MARCS code and extending further in wavelength is used to gauge the emission characteristics of alpha Cen A in the FIR. Similar to the Sun, the FIR emission of alpha Cen A originates in the minimum temperature region above the stellar photosphere in the visible. However, in comparison with the solar case, the FIR photosphere of alpha Cen A appears marginally cooler, Tmin=T160mu=3920+/-375 K. Beyond the minimum near 160mu, the brightness temperatures increase and this radiation likely originates in warmer regions of the chromosphere of alpha Cen A. To the best of our knowledge this is the first time a temperature minimum has been directly measured on a main-sequence star other than the Sun.

Category: Physics