The Gemini NICI planet-finding campaign: The offset ring of HR 4796 A

We present J, H, CH 4 short (1.578 μ m), CH 4 long (1.652 μ m) and K s-band images of the dust ring around the 10 Myr old star HR 4796 A obtained using the Near Infrared Coronagraphic Imager (NICI) on the Gemini-South 8.1 m Telescope. Our images clearly show for the first time the position of the star relative to its circumstellar ring thanks to NICI s translucent focal plane occulting mask. We employ a Bayesian Markov chain Monte Carlo method to constrain the offset vector between the two. The resulting probability ...