The Closest Dusty Cloud Ever Detected Around a R CrB Variable Star Using the VLTI/MIDI Instrument

Monochromatic model: In a first-order analysis, we neglected any variations with wavelength of the source geometry and fitted the curves with simple monochromatic geometric models, obtaining a global morphology in the N-band. Proposed model: central star + dust cloud + extended circumstellar envelope. Results for the best fit to the visibility curves (see Fig. 1): • Separation between the cloud and the central star: 16 ± 1 mas. • PA of the cloud: 75◦ ± 10◦ (modulo 180◦). • FWHM of the Gaussian CSE: 18 ± 3 mas. • Flux contributions to the total N-band flux of the whole system: 10% ± 2% for the central star and 8% ± 2% for the cloud.