Cygnus A: stars, dust and cones

We present new Hubble Space Telescope ( HST  ) continuum and spectral line images of the radio galaxy Cygnus A. The images show much complex structure in the central kpc². Continuum images show the central dust lane in detail, allowing detailed maps of E ( B  ?  V ) to be constructed; the dust appears to follow a roughly Galactic extinction law. The emission-line components are resolved in the line images and investigated in detail. A clear 'opening cone' morphology is found, especially in the lines of Hα and O  i ]. Blue condensations are seen in the south-eastern emission component and surrounding the central region. These are almost certainly due to star formation, which began <1 Gyr ago as deduced from the colour of the regions. More extended blue continuum is also seen and corresponds to the blue polarized component detected by other recent spectropolarimetric observations.