2012A&A...543A.162V

We investigate the structure of the circumstellar disk of the T Tauri star S CrA N and test whether the observations agree with the standard picture proposed for Herbig Ae stars. Our observations were carried out with the VLTI/AMBER instrument in the H and K bands with the low spectral resolution mode. For the interpretation of our near-infrared AMBER and archival mid-infrared MIDI visibilities, we employed both geometric and temperature-gradient models. To characterize the disk size, we first fitted geometric models consisting of a stellar point source, a ring-shaped disk, and a halo structure to the visibilities. In the H and K bands, we measured ring-fit radii of 0.73±0.03mas (corresponding to 0.095±0.018AU for a distance of 130pc) and 0.85±0.07mas (0.111±0.026AU), respectively. This K-band radius is approximately two times larger than the dust sublimation radius of ≃0.05AU expected for a dust sublimation temperature of 1500K and gray dust opacities, but approximately agrees with the prediction of models including backwarming (namely a radius of ≃0.12AU). The derived temperature-gradient models suggest that the disk is approximately face-on consisting of two disk components with a gap between star and disk. The inner disk component has a temperature close to the dust sublimation temperature and a quite narrow intensity distribution with a radial extension from 0.11AU to 0.14AU. Both our geometric and temperature-gradient models suggest that the T Tauri star S CrA N is surrounded by a circumstellar disk that is truncated at an inner radius of ≃0.11AU. The narrow extension of the inner temperature-gradient disk component implies that there is a hot inner rim.