The extended blue continuum and line emission around the central radio galaxy in Abell 2597

We present results from detailed imaging of the centrally dominant radio el liptical galaxy in the cooling-flow cluster Abell 2597, using data obtained with the Wide Field and Planetary Camera 2 (WFPC2) on the Hubble Space Tel escope (HST). This object is one of the archetypal "blue-lobed" cooling-flo w radio elliptical galaxies, also displaying a luminous emission-line nebul a, a compact radio source, and a significant dust lane and evidence of mole cular gas in its center. We show that the radio source is surrounded by a c omplex network of emission-line filaments, some of which display a close sp atial association with the outer boundary of the radio lobes. We present a detailed analysis of the physical properties of ionized and neutral gas ass ociated with the radio lobes, and show that their properties are strongly s uggestive of direct interactions between the radio plasma and ambient gas. We resolve the blue continuum emission into a series of knots and clumps, a nd present evidence that these are most likely due to regions of recent sta r formation. We investigate several possible triggering mechanisms for the star formation, including direct interactions with the radio source, filame nts condensing from the cooling flow, or the result of an interaction with a gas-rich galaxy, which may also have been responsible for fueling the act ive nucleus. We propose that the properties of the source are plausibly exp lained in terms of accretion of gas by the cD during an interaction with a gas-rich galaxy, which, combined with the fact that this object is located at the centre of a dense, high-pressure intracluster medium, can account fo r the high rates of star formation and the strong confinement of the radio source.