New images of a dying star at the centre of a well-known planetary nebula 2,600 light years from Earth have revealed it to be a triple-star system, according to an international team of scientists.
The team led by researchers at Cardiff University's School of Physics and Astronomy, say the images of the Ring Nebula captured by JWST between July and August 2022 provide never-before-seen detail of its structure.
With unprecedented spatial resolution and spectral sensitivity, the images reveal some 20,000 dense globules in the nebula, which are rich in molecular hydrogen. Outside the bright ring is a visible halo with hundreds of radial spikes and roughly ten concentric arcs.
The arcs are thought to originate from the interaction of the central star with a low-mass companion orbiting at a distance comparable to that between the Earth and the dwarf-planet Pluto. In this way, nebulae like the Ring Nebula reveal a kind of astronomical archaeology, as astronomers study the nebula to learn about the star that created it.
Dr Roger Wesson, a Research Associate at Cardiff University's School of Physics and Astronomy who led the analysis, said: "These new images taken with JWST reveal structures that no previous telescope could detect.
"We can now see the subtle influence of a third, previously unknown star in the system, alongside a much more distant companion which was identified in 2021. This third star has sculpted the outflow from the dying central star of the nebula and imprinted a faint concentric pattern into the outer parts of the nebula."
Planetary nebulae such as the Ring form when stars with up to about eight times the mass of our Sun exhaust the hydrogen in their cores and eject their outer layers.
As the source of much of the carbon and nitrogen in the universe, the way in which these stars evolve and die is crucial to understanding the origin of these elements, without which life on Earth could not have developed.
Dr Wesson added: "Planetary nebulae were once thought of as very simple objects, roughly spherical and with a single star at their centre. Hubble showed that they were much more complicated than that, and with these latest images JWST is revealing yet more intricate detail in these objects.
"The evidence that the star has a close binary companion shaping its outflow provides some long-sought answers about how this intricate detail arises."
