White dwarf stars come in pink, purple and green, study finds; astronomers spot first known green star

University of Warwick team finds density and atmospheric chemistry give stellar remnants a surprising range of colours

By LineZotpaper

Published21 October 2026

Read Time2 min

White dwarf stars are not always white. Researchers at the University of Warwick in the U.K. have found that these dense stellar remnants can glow pink, cyan, yellow, purple and even green, including the first green star ever documented. The peer-reviewed findings were published October 15, 2026 in RAS Techniques and Instruments.

A team led by Mark Hollands at the University of Warwick modeled how white dwarf stars would appear to the human eye, using existing spectral data and a model of human color vision. Most stars behave like perfect radiators, with color set almost entirely by temperature. But the researchers found that the extreme density of white dwarfs allows trace elements such as carbon, calcium and sodium to interact with dense helium plasma, producing a much wider range of colors.

"It turns out these incredibly dense stars can produce colors nobody expected, and some of them genuinely surprised me," Hollands said.

The colors fall into groups based on atmosphere. Carbon-rich white dwarfs tend to be pink or purple, those polluted by debris from asteroids or comets tend to be yellow, and those with hydrogen and helium atmospheres appear more cyan or blue.

The most striking result is WD J1330+6435, described as the first documented green star. "The traces of sodium in the atmosphere of this white dwarf absorb the orange part of the spectrum, leaving behind a ghostly green glow," Hollands said. "Imagine standing on a planet and looking up at a green star. It feels like something out of science fiction."

The researchers may also have found the reddest star ever seen. White dwarf WD J1011+2845, 48 light-years from Earth, has a deep convection zone that brings carbon to the surface, squeezing almost all of its light beyond 600 nanometers and producing a salmon-pink glow unlike any ordinary star.

Most white dwarfs remain white. In a representative sample of 151 white dwarfs within 65 light-years of Earth, only five showed unusual colors: three pink and two yellow. The typical white dwarf has a color temperature of about 6,800 Kelvin, which looks white to the human eye.

Analysis

Why This Matters

The finding overturns the assumption that white dwarfs are simply white or colored only by temperature, adding a new layer of complexity to how stellar remnants are classified.
WD J1330+6435 is the first confirmed green star ever recorded, a color previously absent from stellar observations.
Understanding white dwarf colors could deepen knowledge of the remnants most stars, including our sun, will eventually become.

Background

White dwarfs are the hot, dense cores left behind when stars run out of fuel and blow their outer gases into space. They are not ordinary stars: their material can be millions of times denser than the sun's visible surface. Most white dwarfs behave like perfect radiators, so their color is tied to temperature. This study shows that density and atmospheric chemistry can override that simple relationship in the coolest, most compressed remnants.

Key Perspectives

Researchers (University of Warwick): The surprising colors are a real physical effect, produced when trace elements interact with dense helium plasma, and they are visible in several distinct groups depending on what contaminates the star's atmosphere. Astronomers studying stellar surveys: The findings suggest that surveys may over-represent hot, blue white dwarfs because they can be seen from farther away, meaning nearby colorful examples could be more common than previously realized. Skeptics: The colors were not observed directly but computed from spectral data using a model of human color vision, so the exact appearance of these stars at close range may differ from the visualizations.

What to Watch

Whether further surveys turn up additional green white dwarfs, which would confirm WD J1330+6435 is not a one-off.
Follow-up observations of WD J1011+2845 to verify its status as the reddest star known.
Future study of white dwarfs within the local neighborhood to measure how often unusual colors actually occur.

Sources

Surprising colors of white dwarf stars revealed for 1st time · EarthSky

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12 claims in this story checked against 1 source: 12 supported.

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SupportedWhite dwarfs can glow pink, cyan, yellow, purple and green.EarthSky: “white dwarfs can glow in pink, cyan, yellow, purple and green.”
SupportedWD J1330+6435 is the first documented green star.EarthSky: “It is the first documented green star. Astronomers have been on the lookout for green stars, but never confirmed one, until now.”
SupportedHollands said the dense stars can produce unexpected colours that surprised him.EarthSky: “It turns out these incredibly dense stars can produce colors nobody expected, and some of them genuinely surprised me.”
SupportedTrace elements interact with dense helium plasma, contributing to the wider range of colours.EarthSky: “This causes trace elements in the white dwarfs — such as carbon, calcium and sodium — to interact with the dense helium plasma. And they do so across a wide range of colors, wider than in less dense white dwarfs.”
SupportedCarbon-rich white dwarfs tend to look pink or purple.EarthSky: “The first group is carbon-rich white dwarfs. They tend to be pink or purple in color.”
SupportedWhite dwarfs polluted by asteroid or comet debris tend to look yellow.EarthSky: “white dwarfs with atmospheres polluted by debris from asteroids or comets tend to be more yellow.”
SupportedWhite dwarfs with hydrogen and helium atmospheres appear cyan or blue.EarthSky: “white dwarfs that have hydrogen and helium atmospheres are more cyan or blue.”
SupportedHollands said sodium absorbs orange light from the white dwarf, leaving a green glow.EarthSky: “The traces of sodium in the atmosphere of this white dwarf absorb the orange part of the spectrum, leaving behind a ghostly green glow.”
SupportedHollands said imagining a planet beneath a green star felt like science fiction.EarthSky: “Imagine standing on a planet and looking up at a green star. It feels like something out of science fiction.”
SupportedResearchers may have identified the reddest star seen so far.EarthSky: “the researchers might have identified the reddest star ever seen so far.”
SupportedWD J1011+2845 is 48 light-years from Earth.EarthSky: “White dwarf WD J1011+2845 is 48 light-years from Earth.”
SupportedIn a sample of 151 white dwarfs within 65 light-years, five had unusual colours: three pink and two yellow.EarthSky: “The researchers also looked at a more representative sample of white dwarfs, within 65 light-years of Earth. Of the 151 white dwarfs studied, just five displayed the unique coloring. Three of those stars were pink and two were yellow.”