Imagerie des étoiles évoluées par interférométrie. Réarrangement de pupille - Astrophysics > Instrumentation and Methods for AstrophysicsReport as inadecuate




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Abstract: Atmospheric turbulence is an important limit to high angular resolution inastronomy. Interferometry resolved this issue by filtering the incoming lightwith single-mode fibers. Thanks to this technique, we obtained with the IOTAinterferometer very precise measurements of the spatial frequencies of sevenevolved stars. From these measurements, we performed a blind deconvolution torestore an image of the surface of the stars. Six of the them, Betelgeuse, MuCep, R leo, Mira, Chi Cyg and CH Cyg, feature very asymmetrical brightnessdistributions. On the other hand, the Arcturus data are extremely well fittedwith a simple limb-darkened photospheric disc. From the observations of $\chi$Cyg, we show that the star is surrounded by a molecular shell undergoing aballistic motion. We propose to use the same technique of spatial filteringwith single-mode fibers to correct for the effect of turbulence in the pupil ofa telescope. Because the pupil is redundant, this technique does require aremapping of the pupil. We developed a dedicated algorithm to show that it waspossible to reconstruct images at the diffraction limit of the telescope freeof any speckle noise. Our simulations show that a high dynamic range over10^6 could be obtained in the visible on an 8 meter telescope. A labexperiment is under construction to validate the concept of this newinstrument.



Author: Sylvestre Lacour

Source: https://arxiv.org/



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