JWST reveals the Ring Nebula like never before

Out there in space, the stars remind us that even our Sun won’t live forever.

This cutaway showcases the various regions of the surface and interior of the Sun, including the core, which is the only location where nuclear fusion occurs. As time goes on and hydrogen is consumed, the helium-containing region in the core expands and the maximum temperature increases, causing the Sun’s energy output to increase. The balance between the inward-pulling gravity and the outward-pushing radiation pressure is what determines the size and stability of a star.

All stars eventually exhaust their nuclear fuel, running out of fusible material.

The Egg Nebula, as imaged here by Hubble, is a preplanetary nebula, as its outer layers have not yet been heated to sufficient temperatures by the central, contracting star to become fully ionized. Many of the giant stars visible today will evolve into a nebula like this before shedding their outer layers completely and dying in a white dwarf/planetary nebula combination. As the central star loses mass, the outermost objects in that stellar system, such as the analogue of our Oort cloud and Kuiper belt, become ejected.

For Sun-like stars, they’ll grow into red giants, and afterward, gently die away.

When the central star in a dying stellar system heats up to about temperatures of ~30,000 K, it becomes hot enough to ionize the previously ejected material, creating a true planetary nebula in the case of a Sun-like star. Here, NGC 7027 has just recently crossed that threshold, and is still rapidly expanding. At just ~0.1-to-0.2 light-years across, it is one of the smallest and youngest planetary nebulae known.

They first pulse, blowing off their outer, gaseous layers.

Around a variety of stellar corpses and dying stars, doubly-ionized oxygen atoms produce a characteristic green glow, as electrons cascade down the various energy levels when heated to temperatures exceeding ~50,000 K. Here, the planetary nebula IC 1295 shines brilliantly. This phenomenon also helps color the so-called “green pea” galaxies, as well as Earth’s aurorae.

Then the central, fuel-exhausted star contracts and heats up: forming a white dwarf.

When our Sun runs out of fuel, it will become a red giant, followed by a planetary nebula with a white dwarf at the center. The Cat’s Eye Nebula is a visually spectacular example of this potential fate, with the intricate, layered, asymmetrical shape of this particular one suggesting a binary companion. At the center, a young white dwarf heats up as it contracts, reaching temperatures tens of thousands of Kelvin hotter than the surface of the red giant that spawned it. The outer shells of gas are mostly hydrogen, which gets returned to the interstellar medium at the end of a Sun-like star’s life.

This heating ionizes and illuminates the ejected material, creating a planetary nebula.

This 2013 image of the Ring Nebula, taken with the Hubble Space Telescope, showcases the visible light features of the Ring Nebula: the closest planetary nebula to Earth. The Nebula, despite its elliptical, ring-like appearance here, is actually shaped like a distorted donut with two lobes, one pointing toward us and one away from us, emerging from the central region.

The closest planetary nebula to Earth is just over ~2000 light-years away: the Ring Nebula.

The Ring Nebula can be found just inside the Summer Triangle in the constellation of Lyra: just south of the brightest star, Vega. Found in between the 2nd and 3rd brightest stars in Lyra’s constellation, the imaginary line connecting the blue giant stars Sheliak and Sulafat contains the Ring Nebula, circled in red, which can be spotted even with a pair of off-the-shelf binoculars.

Discovered in 1779, its ring-like appearance is only part of the story.

Outside of the main features seen in the ring nebula, thin, wispy, outermore populations of gas, mostly hydrogen gas, are revealed by the Large Binocular Telescope at Mount Graham International Observatory. By combining data from multiple observatories, composite images revealing unprecedented features can be constructed.

An enormous set of diffuse, hydrogen-rich shells surround it.

The red outer shells are signs of ionized hydrogen gas, huge and intricate outside the ring itself. Sulfur and Oxygen ions, expelled from the star and prominent in the ring area, are viewed in the other colors shown here. Spectroscopic imaging, where particular emission lines from a specific element, is key to teasing out these features.

Two lobes of low-density gas extend in both directions along our line-of-sight.

This schematic shows the geometry and structure of the Ring Nebula (Messier 57) as it would appear if viewed from the side, rather than along our line-of-sight. This shows the nebula’s wide halo, inner region, lower-density lobes of material stretching toward and away from us, and the prominent, glowing disc.

The “ring” feature appears so prominently because we’re oriented along the nebula’s poles.

This view showcases a three-dimensional model of the Ring Nebula, as well as its inner and outer structures, as we would experience it if it were rotated a full 360 degrees around the main ring structure. Perpendicular lobes, spike-rich emission emerging from dense knots, and the outer halos are all visible.

But JWST’s infrared eyes reveal features superior to any other view.

This three-panel animation fades between visible light (Hubble) views, near-infrared (JWST NIRCam) views, and even cooler mid-infrared (JWST MIRI) views. This planetary nebula is one of the most well-studied in all of history, yet JWST can still reveal features never seen before.

Its high-resolution cameras reveal ~20,000 dense knots of gas inside.

The near-infrared JWST view (with NIRCam) of the Ring Nebula showcases tendril-like filaments emerging from the main ring, a thin series of concentric shells outside the main ring, and wispy, knotty globules on the interior of the main ring: approximately 20,000 of them. The nebula is very hydrogen-rich, with carbon-based molecules appearing in a thin ring.

The inner filaments showcase intricate details as radiation gradually boils them away.

The mid-infrared (JWST MIRI) view of the Ring Nebula showcases the diffuse, low-density gas inside the nebula, the extended filaments emerging outward from the main ring, and the concentric ring features that are likely carved by a binary companion to the Ring Nebula, perhaps located at the same distance that our Solar System’s Kuiper belt is found from our Sun.

Roughly 10 concentric arcs, rich in hydrocarbons, surround the main “ring” feature.

This animated view that transitions between JWST’s NIRCam and JWST’s MIRI views of the Ring Nebula reveals the difference in structure and detail that different wavelengths of light can reveal. The nebula appears bigger in mid-infrared light because outermore, cooler components radiate at wavelengths that are invisible at short wavelengths, but that emit detectable signatures at longer wavelengths.

Inside, warm, lower-density material fills the inner spheroidal region.

This animation fades between JWST’s NIRCam (infrared) views and Hubble’s optical views. JWST reveals additional stars, background galaxies, and gas features both inside and outside the nebula compared to Hubble’s views. The power of JWST’s improved resolution and deeper infrared wavelength coverage is on full display in this animation.

Overall, JWST unveils the Ring Nebula more accurately than ever before.

In 2005, NASA’s Spitzer, the infrared space telescope that paved the way for JWST, imaged the Ring Nebula and discovered this interior and exterior set of structures around it. Compared to JWST’s views, it’s easy to see what improvements have occurred from the previous to the current generation of infrared space telescopes.

Mostly Mute Monday tells an astronomical story in images, visuals, and no more than 200 words.