Aims. We study the enigmatic B[e] star MWC 300 to investigate its disk and binary with milli-arcsecond-scale angular resolution. Methods. We observed MWC 300 with the VLTI/AMBER instrument in the H and K bands and compared these observations with temperature-gradient models to derive model parameters. Results. The measured low visibility values, wavelength dependence of the visibilities, and wavelength dependence of the closure phase directly suggest that MWC 300 consists of a resolved disk and a close binary. We present a model consisting of a binary and a temperature-gradient disk that is able to reproduce the visibilities, closure phases, and spectral energy distribution. This model allows us to constrain the projected binary separation (∼4.4 mas or ∼7.9 AU), the flux ratio of the binary components (∼2.2), the disk temperature power-law index, and other parameters.

Aims. We study the sub-AU-scale circumstellar environment of the Herbig Ae star HD 144432 with near-infrared VLTI/AMBER observations to investigate the structure of its inner dust disk. Methods. The interferometric observations were carried out with the AMBER instrument in the H and K band. We interpret the measured H-and K-band visibilities, the near-and mid-infrared visibilities from the literature, and the spectral energy distribution (SED) of HD 144432 by using geometric ring models and ring-shaped temperature-gradient disk models with power-law temperature distributions.Results. We derive a K-band ring-fit radius of 0.17 ± 0.01 AU and an H-band radius of 0.18 ± 0.01 AU (for a distance of 145 pc). This measured K-band radius of ∼0.17 AU lies in the range between the dust sublimation radius of ∼0.13 AU (predicted for a dust sublimation temperature of 1500 K and gray dust) and the prediction of models including backwarming (∼0.27 AU). We find that an additional extended halo component is required in both the geometric and temperature-gradient modeling. In the best-fit temperaturegradient model, the disk consists of two components. The inner part of the disk is a thin ring with an inner radius of ∼0.21 AU, a temperature of ∼1600 K, and a ring thickness ∼0.02 AU. The outer part extends from ∼1 AU to ∼10 AU with an inner temperature of ∼400 K. We find that the disk is nearly face-on with an inclination angle of <28 • . Conclusions. Our temperature-gradient modeling suggests that the near-infrared excess is dominated by emission from a narrow, bright rim located at the dust sublimation radius, while an extended halo component contributes ∼6% to the total flux at 2 μm. The mid-infrared model emission has a two-component structure with ∼20% of the flux originating from the inner ring and the rest from the outer parts. This two-component structure is indicative of a disk gap, which is possibly caused by the shadow of a puffed-up inner rim.