First identified in the early 19th century, the Helix Nebula is one of the closest to Earth, located about 650 light-years away in the constellation Aquarius. Astronomers have long studied it with various instruments, but Webb's new data provides unprecedented clarity. This proximity makes it an ideal laboratory for understanding the fate of stars similar to our Sun, revealing precise details about stellar transformation.
Thanks to its infrared instruments, Webb allows examination of the nebula's details, revealing comet-like structures and intense stellar winds. These elements show how gas expelled by the star disperses into space, providing the essential ingredients for the formation of new celestial bodies. Images from the NIRCam camera highlight gaseous pillars around the inner edge of the expanding shell, created by the collision of hot winds with cooler layers.
This image of the Helix Nebula, captured by Webb's NIRCam instrument, includes direction arrows, a scale bar, and a color key for reference. Infrared wavelengths have been translated into visible colors to represent differences in temperature and composition.
Credit: NASA, ESA, CSA, STScI, A. Pagan (STScI) Comparison with previous observations, such as those from the Hubble Space Telescope, highlights Webb's superior performance in infrared for capturing temperature nuances. The transitions from hot ionized gas near the center to cooler molecular regions outside now appear much sharper. This enhanced perspective helps scientists better trace the evolution of the nebula.
At the heart of the nebula, a white dwarf radiates and illuminates the surrounding gas, although it is out of frame in Webb's image. This remnant star is responsible for creating gaseous layers with distinct properties, from hot ionized gas to cold pockets rich in dust. These regions contain the raw material that could one day participate in the formation of stars and planets elsewhere, illustrating how the stellar cycle perpetuates itself.
The colors in Webb's image are not merely aesthetic; they indicate differences in temperature and chemical composition. Blue represents the hottest gas, energized by ultraviolet radiation, while yellow marks areas where hydrogen forms molecules. Red traces the coldest materials at the periphery, where the gas thins and dust can form. These shades help visualize how a star's final ejection becomes the building blocks of future worlds.
These observations deepen our understanding of planetary formation by showing that material ejected by dying stars, as in the Helix Nebula, contains the elements needed to seed new systems. The international collaboration behind Webb, involving NASA, ESA, and CSA, made this unprecedented view possible, paving the way for further discoveries about cosmic evolution.
This image of the Helix Nebula from the VISTA telescope (left) presents the full view of the planetary nebula, with a frame highlighting the narrower field captured by Webb's NIRCam camera (right).
Credit: NASA, ESA, CSA, STScI, A. Pagan (STScI) Planetary nebulae
Planetary nebulae are shells of gas and dust ejected by medium-mass stars, like our Sun, during their final phases. This phenomenon occurs when the star exhausts its nuclear fuel and begins to contract, releasing its outer layers into space. Despite their name, these nebulae have no direct link to planets; the term comes from their round, fuzzy appearance in early telescopes, reminiscent of planetary disks.
The formation of a planetary nebula is a gradual process that lasts thousands of years. The central star, having become a white dwarf, emits intense radiation that ionizes the surrounding gas, causing it to glow at different wavelengths. This light reveals detailed architectures, such as rings or jets, shaped by stellar winds and interactions with the interstellar medium. These nebulae are ephemeral on a cosmic scale, dissipating after a few tens of thousands of years.
By dispersing heavy elements, such as carbon and oxygen, into space, planetary nebulae play a central role in the chemical enrichment of the galaxy. These materials later serve as the basis for the formation of new stars and planets, perpetuating the cycle of stellar life. Studying these objects helps astronomers understand stellar evolution and the composition of the Universe.