Some celebrities save the best for last. For thousands of years, the dimmer star at the center of this scene has been sending out rings of gas and dust in all directions, and NASA’s James Webb Space Telescope has revealed for the first time that this star is cloaked in dust.
Two cameras aboard Webb captured the most recent image of this planetary nebula, known colloquially as the Southern Ring Nebula and catalogued as NGC 3132. It is about 2,500 light-years away.
Webb will allow astronomers to learn more about planetary nebulae like this one, which is clouds of gas and dust ejected by dying stars. Understanding which molecules are present and where they are located within the shells of gas and dust will aid researchers in refining their understanding of these objects.
This observation shows the Southern Ring Nebula almost face-on, but if we could rotate it to view it edge-on, its three-dimensional shape would look more clearly like two bowls joined at the bottom, opening away from one another with a large hole in the centre.
The local landscape is shaped by two stars in a tight orbit. In this complex system, Webb’s infrared images reveal new details. The stars—and their layers of light—are visible in the left image from Webb’s Near-Infrared Camera (NIRCam), while the right image from Webb’s Mid-Infrared Instrument (MIRI) reveals for the first time that the second star is surrounded by dust. The brighter star is further along in its stellar evolution and will most likely eject its own planetary nebula in the future.
Meanwhile, the brighter star influences the appearance of the nebula. As the two continue to orbit each other, they “stir the pot” of gas and dust, resulting in asymmetrical patterns.
Each shell represents an episode in which the fainter star lost mass. The widest shells of gas toward the image’s edges were ejected first. The most recent are those closest to the star. Tracing these ejections allows researchers to investigate the system’s history.
NIRCam observations also reveal extremely fine light rays surrounding the planetary nebula. Starlight from the central stars shines through gaps in the gas and dust, much like sunlight does through gaps in a cloud.
Because planetary nebulae have been around for tens of thousands of years, observing one is like watching a movie in super slow motion. Researchers can precisely measure the gas and dust present within each shell that the star puffed off.
Dust and molecules form within the shells of material ejected by the star, changing the landscape even as the star continues to expel material. This dust will eventually enrich the areas around it, eventually expanding into the interstellar medium. Because dust is so long-lived, it could end up travelling through space for billions of years before becoming incorporated into a new star or planet.
These delicate layers of gas and dust will dissipate into the surrounding environment over thousands of years.