A new infrared image of NGC 2392 shows a bubble of ionized gas, rings, and comet-like dust clumps around the hot core of a dying star. The nebula is expected to dissipate within about 10,000 years.
James Webb Space Telescope Photographed the NGC 2392, a planetary nebula known asThe Lion NebulaThe image combines near- and mid-infrared observations and reveals dense dust structures alongside ionized gas.
At the center of the nebula is the fiery core left over from a dying star. In the image, it appears as a small point of light, resembling a lion's nose. Around it extend rings, bubbles, tendrils, and clumps of dust that together form a structure reminiscent of a face and a mane.
This is a publication of an image and scientific explanation by ESA/Webb, and not an announcement of a new peer-reviewed research paper.
A planetary nebula not associated with planets
NGC 2392 is located in the constellation Gemini, about 5,000 light-years from Earth, according to NASA. William Herschel identified it as early as 1787.
Despite its name, a planetary nebula is not related to planets. It is a historical name for objects that appeared round and fuzzy in early telescopes and reminded astronomers of planetary disks.
Such a nebula forms when a low- or intermediate-mass star reaches a late stage in its evolution. After the nuclear reactions in its core change, the star becomes unstable and ejects its outer layers. The ejected material spreads out, forming envelopes of gas and dust.
The exposed core remains very hot. Its radiation ionizes the expelled gas and causes the nebula to glow. Later, the core will become a white dwarf that gradually cools.
A similar process is also seen inThe Ring Nebula photographed by Webb, which was also formed from material shed by a star in the final stages of its life.
The bear saw the lion in visible light.
The Hubble Space Telescope imaged NGC 2392 in January 2000 using the Wide Field Planetary Camera 2. The visible-light image revealed a bright inner region and an outer envelope containing comet-like objects.
Observations have shown that the nebula is not a simple sphere. It consists of two elliptical lobes of material, one of which is in front of the other from our perspective. A dense ring of material around the star's equator may influence the direction of the gas's expansion.
Webb does not replace the Hubble image but adds information to it in other wavelength ranges. NIR Cam Watching in the near infrared, while MIRI Focuses on the mid-infrared. These regions are particularly sensitive to dust, molecular hydrogen, and structures that are difficult to see in visible light.
The lion's face is made of ionized gas.
The central core is so hot that its radiation ionizes the hydrogen around it, creating a bubble of ionized gas that visually resembles the lion's "face."
The bubble is not smooth. It contains voids, rings, envelopes, and tendrils. As it expands, it sweeps up material and hits some of the dust grains in its path.
Astronomers are still trying to understand how the wind and radiation from the central core create such complex systems. Asymmetric rings and envelopes have been observed inPlanetary nebulae additional, and sometimes a companion star helps shape them. For example, The Crystal Ball Nebula Surrounds a Binary System.
A “mane” of dust that survived
The "mane" in the image is the inner part of a dust envelope illuminated by the central core. Along the edges of the envelope are dense clumps with comet-like tails.
The clumps have managed to survive so far despite the intense radiation. Their density allows them to block some of the radiation and protect the material behind them. Also visible in the composite image are clumps of molecular hydrogen.
Comet tail-like structures were already visible in the Hubble image. Webb's infrared observations allow us to better discern the composition and distribution of the dust.
Webb revealed similar structures of matter around dying stars as well.PMR 1 Nebula, resembling a brain inside a skull.
The colors in the picture are not the colors the eye would see.
The combined image includes measurements at several wavelengths that are invisible to the human eye. Visible colors have been assigned to the data to differentiate between filters, materials, and structures.
NIRCam data includes wavelengths of 1.15, 1.87, 2.12, and 3.35 microns. Among other things, it tracks ionized hydrogen, molecular hydrogen, and materials containing carbon molecules.
This data was supplemented by a MIRI observation at a wavelength of about 10 microns, which is particularly sensitive to silicates and dust. Therefore, the purple-blue color of the “mane” should not be seen as a representation of its natural color to the eye.
A brief moment in the life of a star
The gas and dust that make up NGC 2392 have been shaped over thousands of years, and they continue to drift away from the central core. Webb's image freezes a single moment in an ongoing process.
According to ESA, the nebula is expected to dissipate within about 10,000 years. This is a relatively short period of time for stellar evolution, which takes millions or billions of years.
After the gas dissipates, the core will remain as a white dwarf. Also White dwarfs are not always completely silent objects: astronomers have documented, for example, Unexplained shock wave around a system containing a white dwarf.
The material ejected by the star will not disappear. It will gradually mix into the interstellar medium and may participate in future generations of stars and planetary systems.
Questions and Answers
What is a planetary nebula?
An expanding envelope of gas and dust ejected by a low- to intermediate-mass star late in its life. The name is historical and does not indicate a connection to planets.
Why is NGC 2392 called the Lion Nebula?
The internal structure resembles the face of a lion, the outer dust shell looks like a mane, and the bright core in the center resembles a small nose.
What do Webb observations add to the Hubble picture?
Hubble observed the nebula primarily in visible light. Webb's NIRCam and MIRI observe in infrared light, which reveals clumps of dust, molecular hydrogen, and regions of ionized gas.
Are the colors in the image the natural colors of the nebula?
No. Infrared light is invisible to the eye, so image processors assigned visible colors to data from different wavelengths.
For the original publication: ESA/Webb image message, Hubble image and NASA historical information
More on the subject on the science website
- From dry rock to water-rich material: DESI analyzed the remains of planets around dead stars
- The Roman Space Telescope will be fueled and ready for launch on August 30th.
- Gemini Telescope Reveals Crystal Ball Nebula: Light from a Dying Star That Began Its Journey to Us About 1,500 Years Ago
- The launch of the Roman space telescope to search for extrasolar planets could take place as early as September 2026
- NASA launches tiny space telescope Pandora to study atmospheres of 20 exoplanets
