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Post Info TOPIC: Arcturus


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Alpha Boötis
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Arcturus (Alpha Boötis, HD 124897) is a red giant star located 36.7 light-years away in the constellation of Boötes

Picture 835 
Date: 15.05.17 


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RE: Arcturus
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Picture 342 
Date: 20.04.15 


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Picture 008Picture 007
Date 23.03.15 


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Picture 005Picture 011
 Arcturus labelled image. 


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Arcturus culminates at midnight on 27 April

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Title: The limb-darkened Arcturus; Imaging with the IOTA/IONIC interferometer
Authors: S. Lacour, S. Meimon, E. Thiebaut, G. Perrin, T. Verhoelst, E. Pedretti, P. A. Schuller, L. Mugnier, J. Monnier, J.P. Berger, X. Haubois, A. Poncelet, G. Le Besnerais, K. Eriksson, R. Millan-Gabet, M. Lacasse, W. Traub

This paper is an H band interferometric examination of Arcturus, a star frequently used as a spatial and spectral calibrator. Using the IOTA 3 telescope interferometer, we performed spectro-interferometric observation (R~35) of Arcturus. Atmospheric models and prescriptions were fitted to the data to derive the brightness distribution of the photosphere. Image reconstruction was also obtained using two software algorithms: Wisard and Mira. An achromatic power law proved to be a good model of the brightness distribution, with a limb darkening compatible with the one derived from atmospheric model simulations using our Marcs model. A Rosseland diameter of 21.05±0.21 was derived, corresponding to an effective temperature of T_eff=4295±26 K. No companion was detected from the closure phases, with an upper limit on the brightness ratio of 8e-4 at 1AU. Dynamic range at such distance from the photosphere was established at 1.5e-4 (1sigma rms). An upper limit of 1.7e-3 was also derived for the level of brightness asymmetries present on the photosphere.

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