Ground - based near - infrared imaging of the HD 141569 circumstellar disk

We present the first ground-based near-infrared image of the circumstellar disk around the post-Herbig Ae/Be star HD141569A initially detected with the HST. Observations were carried out in the near-IR (2.2 µm) at the Palomar 200-inch telescope using the adaptive optics system PALAO. The main large scale asymmetric features of the disk are detected on our ground-based data. In addition, we measured that the surface brightness of the disk is slightly different than that derived by HST observations (at 1.1 µm and 1.6 µm). We interpret this possible color-effect in terms of dust properties and derive a minimal grain size of 0.6 ± 0.2µm for compact grains and a power law index for the grain size distribution smaller than −3. Basic dynamical considerations are consistent with the presence of a remnant amount of gas in the disk.