Pan of HH 797

This image was captured with Webb’s Near-InfraRed Camera (NIRCam). Infrared imaging is powerful in studying newborn stars and their outflows, because the youngest stars are invariably still embedded within the gas and dust from which they are formed. The infrared emission of the star’s outflows penetrates the obscuring gas and dust, making Herbig-Haro objects ideal for observation with Webb’s sensitive infrared instruments. Molecules excited by the turbulent conditions, including molecular hydrogen and carbon monoxide, emit infrared light that Webb can collect to visualise the structure of the outflows. NIRCam is particularly good at observing the hot (thousands of degree Celsius) molecules that are excited as a result of shocks.

Using ground-based observations, researchers have previously found that the for cold molecular gas associated with HH 797, most of the red-shifted gas (moving away from us) is found to the south (bottom right), while the blue-shifted gas (moving towards us) is to the north (bottom left). A gradient was also found across the outflow, such that at a given distance from the young central star, the velocity of the gas near the eastern edge of the jet is more red-shifted than that of the gas on the western edge. Astronomers in the past thought this was due to the outflow’s rotation. In this higher resolution Webb image, however, we can see that what was thought to be one outflow is in fact made up of two almost parallel outflows with their own separate series of shocks (which explains the velocity asymmetries). The source, located in the small dark region (bottom right of centre), and already known from previous observations, is therefore not a single but a double star. Each star is producing its own dramatic outflow. Other outflows are also seen in this image, including one from the protostar in the top right of centre along with its illuminated cavity walls.