The limb-darkened Arcturus; Imaging with the IOTA/IONIC interferometer
Abstract
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.
Keywords
Cite
@article{arxiv.0804.0192,
title = {The limb-darkened Arcturus; Imaging with the IOTA/IONIC interferometer},
author = {S. Lacour and S. Meimon and E. Thiebaut and G. Perrin and T. Verhoelst and E. Pedretti and P. A. Schuller and L. Mugnier and J. Monnier and J. P. Berger and X. Haubois and A. Poncelet and G. Le Besnerais and K. Eriksson and R. Millan-Gabet and M. Lacasse and W. Traub},
journal= {arXiv preprint arXiv:0804.0192},
year = {2009}
}
Comments
12 pages, 12 figures, accepted in A&A