Southern Ring Nebula in near- and mid-infrared light
This side-by-side comparison shows observations of the Southern Ring Nebula in near-infrared light (left) and mid-infrared light (right) from the NASA/ESA/CSA Webb Telescope.
This scene was created by a white dwarf star – the remnant of a star like our Sun after it shed its outer layers and stopped burning fuel through nuclear fusion. Those outer layers now form the ejected shells seen in this view.
In the Near-Infrared Camera (NIRCam) image, the white dwarf appears to the lower left of the bright, central star, partially hidden by a diffraction spike. The same star appears – but brighter, larger, and redder – in the Mid-Infrared Instrument (MIRI) image. This white dwarf star is cloaked in thick layers of dust, which make it appear larger.
The brighter star in both images hasn’t yet shed its layers. It closely orbits the dimmer white dwarf, helping to distribute what it’s ejected.
Over thousands of years and before it became a white dwarf, the star periodically ejected mass – the visible shells of material. As if on repeat, it contracted, heated up, and then, unable to push out more material, pulsated. Stellar material was sent in all directions – like a rotating sprinkler – and provided the ingredients for this asymmetrical landscape.
Today, the white dwarf is heating up the gas in the inner regions – which appear blue in the left-hand image and red in the right-hand image. Both stars are lighting up the outer regions, shown in orange and blue, respectively.
The images look very different because NIRCam and MIRI collect different wavelengths of light. NIRCam observes near-infrared light, which is closer to the visible wavelengths our eyes detect. MIRI goes farther into the infrared, picking up mid-infrared wavelengths. The second star appears more clearly in the MIRI image, because this instrument can see the gleaming dust around it, bringing it more clearly into view.
The stars – and their layers of light – steal more attention in the NIRCam image, while dust plays the lead in the MIRI image, specifically dust that is illuminated.
Peer at the circular region at the centre of each image. Each contains a wobbly, asymmetrical belt of material. This is where the two ‘bowls’ that make up the nebula meet. (In this view, the nebula is at a 40-degree angle.) This belt is easier to spot in the MIRI image – look for the yellowish circle – but is also visible in the NIRCam image.
The light that travels through the orange dust in the NIRCam image – which look like spotlights – disappears at longer infrared wavelengths in the MIRI image.
In near-infrared light, stars have more prominent diffraction spikes because they are so bright at these wavelengths. In mid-infrared light, diffraction spikes also appear around stars, but they are fainter and smaller (zoom in to spot them).
Physics explains the difference in the resolution of these images. NIRCam delivers high-resolution imaging because these wavelengths of light are shorter. MIRI supplies medium-resolution imagery because its wavelengths are longer; the longer the wavelength, the coarser the images are. But both deliver an incredible amount of detail about every object they observe – providing never-before-seen vistas of the universe.
Read more about Webb's observations of the Southern Ring Nebula
