Asymmetries in the HD141569 circumstellar disk

We present HST/STIS coronagraphic observations of the disk around HD141569. The data, with a spatial resolution and signal to noise higher than those previously obtained with HST/NICMOS2 allow a more detailed insight in the s ystem. They reveal a very structured system, in which two ring-like structu res at distances similar or equal to 200 and 325 AU from the star are the m ost prominent features. The region between 125 and 175 AU is clearly devoid of material. An arc-like structure is also detected at about 250 AU, as we ll as a diffuse extended emission, both on the North side of the disk. The system appears to be highly asymmetrical, both with respect to its major an d minor axes. Surprisingly, the brightness asymmetry with respect to both a xes in the inner and outer parts of the disk is reversed. Possible explanat ions to the asymmetries include anisotropic scattering and/or non axisymmet rical distribution of the dust within the system. It is shown that anisotro pic scattering cannot alone be responsible for all observed asymmetries. It is concluded that HD141569 disk is non axi-symmetrical. Eventhough no deta iled modeling is given in this observational paper, it is probable that the sculpting and brightness properties of the disk are due to the gravitation al perturbation of a massive body.