Astronomers reveal a dead star glowing an eerie shade of green

White dwarf WD J1330+6435 may be the first star known to shine in a colour ordinary stars cannot produce

By LineZotpaper AI staff

Published26 October 2026

Read Time3 min

Illustration: Astronomers reveal a dead star glowing an eerie shade of green

Astronomers have found what they say is the first known star that would appear green to the human eye: a white dwarf, or dead star, named WD J1330+6435. Research led by astrophysicist Mark Hollands of the University of Warwick shows the star's ultra-dense atmosphere suppresses other colours, leaving a ghoulish chartreuse glow.

Stars are rarely pure white, but green has long been missing from the stellar palette. Now astronomers report an exception: a white dwarf, the remnant core of a star that has exhausted its nuclear fuel, that would shine a startling shade of chartreuse green if viewed up close.

The finding comes from research led by Mark Hollands of the University of Warwick, published in RAS Techniques and Instruments. Hollands and his team selected dozens of white dwarfs already identified as spectrally unusual and calculated how the human eye would perceive the light each one emits.

"Most stars, including most white dwarfs, behave like 'perfect radiators,' so their color is set almost entirely by temperature. But nobody had really looked into what else might be possible for white dwarfs," Hollands said. "It turns out these incredibly dense stars can produce colors nobody expected, and some of them genuinely surprised me."

White dwarfs are extraordinarily compact, packing up to 1.4 times the Sun's mass into a body roughly the size of Earth. In the densest of them, atmospheric density can approach that of liquid water, millions of times denser than the Sun's atmosphere. At such densities, atoms interact with their neighbours and absorb much broader swathes of light than they would in an ordinary star.

In WD J1330+6435, with a surface temperature of about 4,240 Kelvin, sodium in the atmosphere absorbs a broad band of orange-yellow light while calcium suppresses violet, allowing green to dominate.

"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 star's colour may also tell a darker story. Alongside sodium and calcium, astronomers detected lithium, a sign of rocky material consistent with the dead star having consumed debris from its former planetary system. The researchers note that most white dwarfs are white; of 152 nearby white dwarfs examined, only about one in 30 had colours significantly different from those expected from temperature alone.

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Analysis

Why This Matters

The discovery challenges the long-held assumption that star colour is set almost entirely by temperature, showing that ultra-dense stellar remnants can display hues ordinary stars cannot produce.
Unusual white dwarf colours could help astronomers identify stars that have ingested rocky debris from their own planetary systems, supporting the emerging field of necroplanetology.
The finding offers a new window into the extreme physics of white dwarf atmospheres, where atoms behave very differently from those in normal stars.

Background

White dwarfs form from the cores of stars that have ejected their outer material after running out of fusion fuel, shining with residual heat instead. Their intense gravity compresses enormous mass into an Earth-sized object. Normally, a star's perceived colour depends on the balance of wavelengths it emits, which is set by its temperature. Because stars emit light across the whole spectrum, green is usually mixed with so many other colours that it does not dominate. In the dense atmosphere of a white dwarf, however, atoms can absorb unusually broad ranges of wavelengths, suppressing other colours and letting green break free.

What to Watch

Whether follow-up observations confirm that other white dwarfs in the 152-star sample show similar unusual hues, and whether more green examples turn up beyond the sample.
Further analysis of the lithium and other elements in WD J1330+6435 to determine whether they came from a devoured planetary system.
Whether unusual white dwarf colours are developed as a quick screening tool for stars that have consumed rocky debris.

Sources

In a First, Astronomers Reveal a Dead Star Glowing an Eerie Shade of Green · ScienceAlert

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12 claims in this story checked against 1 source: 11 supported.

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SupportedThe headline says astronomers have revealed a dead star glowing an eerie shade of green.ScienceAlert: “In a First, Astronomers Reveal a Dead Star Glowing an Eerie Shade of Green.”
SupportedThe summary says WD J1330+6435 may be the first star known to shine in a colour ordinary stars cannot produce.ScienceAlert: “But WD J1330+6435, with a surface temperature of just 4,240 Kelvin, would appear a startling shade of chartreuse green – the "most surprising color," the researchers say. Some white dwarfs appeared pink or purple, others vivid blue or cyan – with some displaying hues that ordinary stars simply can't produce.”
SupportedThe story says Hollands and his team found the first known star that would appear green to the human eye.ScienceAlert: “But now astronomers have found an exception – and in an especially apposite twist, it's a white dwarf – the remnant core of a star that's already "dead". It's a star named WD J1330+6435, and according to research led by astrophysicist Mark Hollands of the University of Warwick in the UK, if we could see it up close with the naked eye ... it would shine a ghoulish shade of chartreuse.”
SupportedThe story quotes Hollands saying most stars behave like perfect radiators and that nobody had really looked into what else might be possible for white dwarfs.ScienceAlert: “"Most stars, including most white dwarfs, behave like 'perfect radiators,' so their color is set almost entirely by temperature. But nobody had really looked into what else might be possible for white dwarfs," Hollands says.”
SupportedThe story quotes Hollands saying dense stars can produce unexpected colours that surprised him.ScienceAlert: “"It turns out these incredibly dense stars can produce colors nobody expected, and some of them genuinely surprised me."”
SupportedThe research was led by astrophysicist Mark Hollands of the University of Warwick and published in RAS Techniques and Instruments.ScienceAlert: “according to research led by astrophysicist Mark Hollands of the University of Warwick in the UK”
SupportedThe team selected dozens of white dwarfs already identified as spectrally unusual and calculated how their light would appear to the human eye.ScienceAlert: “They selected dozens of white dwarfs that had already been identified as spectrally weird and conducted a deeper analysis of the colors their light would produce. By examining the wavelengths of light emitted by each star and calculating how the human eye would perceive them, the researchers were able to predict what colors the stars would appear if viewed up close.”
SupportedWD J1330+6435 has a surface temperature of about 4,240 Kelvin, and its sodium and calcium absorption allows green to dominate.ScienceAlert: “But WD J1330+6435, with a surface temperature of just 4,240 Kelvin, would appear a startling shade of chartreuse green”
SupportedThe story says white dwarfs can have up to 1.4 times the Sun's mass in a body roughly the size of Earth.ScienceAlert: “these exposed cores – shining instead with residual heat – are extraordinarily compact, with masses up to 1.4 Suns squeezed into a body roughly the size of Earth.”
Partly supportedThe story says the densest white dwarfs can have atmospheric densities approaching liquid water's, millions of times the Sun's atmospheric density.ScienceAlert: “the atmospheres of the coolest white dwarfs can reach densities comparable to liquid water – millions of times denser than the Sun's atmosphere.”
SupportedThe story says astronomers detected lithium in WD J1330+6435, consistent with the star having consumed debris from its former planetary system.ScienceAlert: “In addition to sodium and calcium, astronomers have also detected lithium in WD J1330+6435 – all signs of rocky material, consistent with the dead star feasting on the debris of its former planetary system.”
SupportedThe story says that of 152 nearby white dwarfs examined, about one in 30 had colours significantly different from those expected based on temperature alone.ScienceAlert: “Of a sample of 152 nearby white dwarfs, the researchers found that just five – roughly one in 30 – had colors significantly different from those expected based on temperature alone.”