Astronomers Discover First Known Green Star in Space

Astronomers have identified what appears to be the first genuinely green star, an unusual white dwarf whose color challenges traditional ideas about how stars look. The object, named WD J1330+6435, appears yellowish-green in scientific models because of the unusual chemistry of its dense atmosphere.

Located in the constellation Draco, the white dwarf is about 280 light-years from Earth, according to Reuters reporting on the discovery. Researchers led by astrophysicist Mark Hollands of the University of Warwick in England found that material from the star’s former planetary system has altered the way it absorbs light.

The findings, published in the journal RAS Techniques and Instruments, reveal that white dwarfs can display a wider range of colors than astronomers once expected.

Why This Green Star Looks Different

Most stars appear orange, white or blue, with their colors largely determined by surface temperature. The Sun, for example, emits light across a broad range of visible wavelengths, giving it a familiar white appearance from space.

However, white dwarfs follow a more complicated pattern. These objects are the dense remnants of stars that have exhausted their nuclear fuel and shed their outer layers.

Although most white dwarfs appear white, their atmospheric chemistry can produce unusual colors. In the case of WD J1330+6435, researchers believe sodium plays a crucial role.

The star has absorbed rocky material containing calcium, lithium and sodium from its former planetary system. Under the extreme density of its atmosphere, sodium atoms interact with surrounding helium atoms, changing the way they absorb light.

Instead of absorbing only a narrow band of orange light, the sodium absorbs a broader range of yellow, orange and some red wavelengths.

This leaves a greenish appearance in the remaining visible light. Researchers describe the calculated color as chartreuse, a shade between yellow and green.

The effect would not occur in the same way in a Sun-like star because its atmospheric conditions are different.

Scientists Calculated the Star’s Color

Despite the headlines, astronomers did not directly observe a bright green object through a telescope. Instead, they calculated how the star would appear to human eyes by analyzing its spectrum.

A spectrum reveals the different wavelengths of light emitted by an astronomical object. Scientists use these measurements to identify chemical elements and understand the physical conditions surrounding a star.

The research team combined observations with models of human color vision to determine the apparent colors of different white dwarfs.

Their analysis included 151 white dwarfs within approximately 65 light-years of Earth. Most appeared white, but the broader investigation revealed that atmospheric composition can produce several unusual color variations.

This approach is important because a star’s appearance can reveal information that would otherwise remain difficult to identify from its light alone.

A Pink Star Also Surprises Researchers

The green white dwarf was not the only unusual object identified in the research.

Another white dwarf, WD J1011+2845, located about 48 light-years away in the constellation Leo Minor, could appear salmon-pink. In this case, carbon is responsible for the unusual color.

Unlike the green star, which has accumulated material from its planetary system, the pink white dwarf brings carbon from its interior toward its surface.

That carbon changes how the atmosphere absorbs visible light, producing a different color.

The findings suggest that white dwarfs can appear in shades including pink, purple, yellow, cyan and green, depending on their temperature and atmospheric composition.

Nevertheless, unusual colors remain relatively rare. Most white dwarfs in the researchers’ sample appeared white.

What the Discovery Reveals About Former Planets

The discovery offers more than an unusual astronomical curiosity. It also provides clues about the remains of planetary systems.

When a star reaches the end of its life, its planetary system can undergo dramatic changes. Asteroids, rocky fragments and other debris may be disrupted and pulled toward the remaining white dwarf.

When this material accumulates in the star’s atmosphere, it introduces chemical elements that astronomers can detect through spectroscopy.

By studying those elements, researchers can investigate the composition of rocky material that once orbited the star.

WD J1330+6435 therefore provides an example of how a stellar remnant can preserve evidence of its former planetary environment. Its greenish appearance is linked to the same chemical processes that offer clues about the material surrounding it.

The discovery does not mean the star swallowed entire planets in a single event. Rather, the evidence points to the accumulation of rocky debris over time.

Could the Sun Ever Become a Green Star?

The Sun is expected to become a white dwarf billions of years from now, after exhausting its nuclear fuel and passing through later stages of stellar evolution.

However, scientists cannot conclude that the Sun will eventually appear green.

Its future color would depend on its temperature, atmospheric composition and whether rocky debris accumulated around the remnant. Those conditions are different from the circumstances observed in WD J1330+6435.

For now, the discovery demonstrates that the universe can produce surprising stellar colors through familiar physical processes operating under extreme conditions.

By examining more white dwarfs, astronomers may uncover additional examples and learn more about the final stages of stars and the planetary systems they leave behind.