Astronomy & Astrophysics

Table 1: AMBER and MIDI observation log for CPD $-57\hbox{$^\circ$ }~2874$ .
Table 2: Uniform disc diameters and observation log for the calibrators.
Table 3: Photometry of CPD $-57\hbox{$^\circ$ }~2874$ obtained at SAAO.
Table 4: Model parameters and $\chi ^2_{\rm red}$ (reduced chi-squared) derived from the fit of an elliptical Gaussian (Eqs. (1) and (2)) to the AMBER/VLTI and MIDI/VLTI visibilities. Angular sizes (in mas) correspond to FWHM diameters. The errors of the fit parameters include the calibration errors of the instrumental transfer function ( $\simeq$ $5\%$ ), estimated from all calibrator stars observed.