UNCOVERING THE NATURE OF NOVA JETS: A RADIO IMAGE OF HIGHLY COLLIMATED OUTFLOWS FROM RS OPHIUCHI

Novae occur when hydrogen-rich fuel provided by a companion star ignites on the surface of a white dwarf (WD). Although the surface of the WD is nearly spherical, observations indicate that at least some nova explosions can produce bipolar outflows, or jets. The origin and nature of these jets are controversial. Proposed mechanisms for generating the jets include (1) intrinsically asymmetric explosions, (2) ejecta that move into an inhomogeneous environment, and (3) driving by highly collimated outflows such as those from black holes and protostars. Here we present radio images of the symbiotic recurrent nova RS Ophiuchi that strongly support the third option. The images show that the jets associated with the eruption in 2006 consisted of underlying narrow outflows with half-opening angles of just a few degrees that fed extended lobes of relativistic, synchrotron-emitting particles. Assuming a uniform jet velocity, the highly collimated flows persisted for more than a month after the start of the explosion. By revealing highly collimated outflows that begin within days after the eruption, our observations demonstrate that either the explosion did not destroy the accretion disk or an accretion disk is not needed to collimate jets from novae.