High Angular Resolution and Young Stellar Objects: Imaging the Surroundings of MWC 158 by Optical Interferometry

¹ Institut de Planétologie et d’Astrophysique de Grenoble, UMR 5274, BP. 53, 38041 Grenoble Cedex 9, France
² ESO, Santiago Office, Alonso de Cordova 3107, Vitacura, Casilla 19001, Santiago de Chile, Chile

Abstract

In the course of our VLTI young stellar object PIONIER imaging program, we have identified a strong visibility chromatic dependency that appeared in certain sources. This effect, rising value of visibilities with decreasing wavelengths over one base, is also present in previous published and archival AMBER data. For Herbig AeBe stars, the H band is generally located at the transition between the star and the disk predominance in flux for Herbig AeBe stars. We believe that this phenomenon is responsible for the visibility rise effect. We present a method to correct the visibilities from this effect in order to allow “gray” image reconstruction software, like Mira, to be used. In parallel we probe the interest of carrying an image reconstruction in each spectral channel and then combine them to obtain the final broadband one. As an illustration we apply these imaging methods to MWC158, a (possibly Herbig) B[e] star intensively observed with PIONIER. Finally, we compare our result with a parametric model fitted onto the data.