A University of Warwick-led team says a white dwarf called WD J1330+6435, in the constellation Draco, is the first star that would genuinely look green to the human eye. The colour comes from sodium, calcium and lithium pulled from its own planetary debris, which absorb orange light in its dense atmosphere, according to a study published in RAS Techniques and Instruments.
Astronomers led by Mark Hollands of the University of Warwick have identified what they describe as the first credibly documented green star: a white dwarf catalogued as WD J1330+6435, located in the constellation Draco. The finding was published in the journal RAS Techniques and Instruments (RASTI) in a paper titled "Any colour you like: the diverse chromaticities of white dwarfs."
According to the English-language Wikipedia entry for the object, which cites the study's data, WD J1330+6435 lies roughly 280 light-years from Earth, has a surface temperature of about 4,310 kelvin (roughly 4,000 degrees Celsius), a mass near 0.74 times the Sun's, and an estimated age of about 9.1 billion years. Its spectral type, DZ, flags it as a white dwarf whose atmosphere has been polluted by metals.
Why this white dwarf looks green
White dwarfs are the dense, burnt-out cores left behind when Sun-like stars die. Most of them behave as near-perfect radiators, meaning their colour is set almost entirely by temperature, which is why ordinary stars appear only orange, white or blue to the eye. WD J1330+6435 is different because sodium, calcium and lithium — elements astronomers say were dragged onto its surface from the shattered remains of its own planetary system — have built up in its atmosphere.
The traces of sodium in the atmosphere of this white dwarf absorb the orange part of the spectrum, leaving behind a ghostly green glow.
— Mark Hollands, University of Warwick
Several outlets reported that the white dwarf's atmosphere is dense enough that sodium atoms are constantly jostled by surrounding helium, a quantum effect that widens the range of light the sodium absorbs to cover yellow, orange and part of the red spectrum. What remains visible to the eye, researchers say, is a chartreuse-green glow.
No one has actually seen it glow green
No telescope eyepiece has shown this colour directly: WD J1330+6435 is too faint and distant for its hue to be judged by eye. Instead, Hollands' team reconstructed the star's spectrum — the pattern of light split by wavelength, like a prism — and ran it through models of human colour vision to calculate how the star would appear to an observer standing nearby.
The team applied the same method to roughly 150 nearby white dwarfs (151, according to CNN Brasil and Courthouse News; 152, according to Sci.News) in search of stars whose atmospheric chemistry pushes their colour away from the temperature-driven norm. About five of them, or roughly one in 30, showed genuinely unusual colours.
Not the only unusual colour found
The same survey turned up other outliers. WD J1011+2845, about 48 light-years from Earth, appeared as a deep salmon pink because carbon molecules in its atmosphere absorb light beyond roughly 600 nanometres, pushing its perceived colour toward red rather than the blue-white astronomers would expect from its temperature. Sci.News also reported a white dwarf, listed as WD J2356-2054, that appeared vivid blue despite a temperature of only about 4,000 kelvin — a temperature that would normally produce a reddish, not blue, star.
Unusual white dwarf colours identified in the 2026 RASTI survey
White dwarf
Perceived colour
Distance from Earth
Reported cause
WD J1330+6435
Chartreuse green
~280 light-years (Draco)
Sodium, calcium and lithium from planetary debris absorb orange light
Researchers describe the findings cautiously. Agnès Kim of Penn State Scranton, commenting on the study, told CNN that linking a star's measured spectrum to how the human eye would perceive it brings together physics and biology in a way she finds compelling. Adam Burgasser of the University of California, San Diego, compared the chemical traces in such atmospheres to evidence at a crime scene that lets astronomers reconstruct the history of a dead star's planetary system.
Hollands has said that as spectroscopic surveys expand roughly tenfold in the coming years, the number of known green white dwarfs could rise from one or two to somewhere between 10 and 20, according to CNN Brasil's report on the study.
Questions
What is the name of the first green star?
It is WD J1330+6435, a white dwarf in the constellation Draco, identified in a study led by Mark Hollands of the University of Warwick.
Why do stars not normally appear green?
Most stars radiate light according to their temperature alone, which produces only orange, white or blue hues to the human eye; green requires a specific combination of absorbed wavelengths that ordinary stellar physics rarely produces.
How did astronomers know the star would look green if no one has seen it directly?
The team measured the star's spectrum and ran it through models of human colour vision to calculate its perceived colour, since the white dwarf is too faint and distant to be judged by eye through a telescope.
What causes the green colour in WD J1330+6435?
Sodium, calcium and lithium accreted from the remains of its planetary system have built up in its dense atmosphere; the sodium absorbs orange, yellow and part of the red spectrum, leaving a green glow, according to Mark Hollands.
Where was the study published?
In RAS Techniques and Instruments (RASTI), in a paper titled "Any colour you like: the diverse chromaticities of white dwarfs."
How the world is telling it
PortugueseBrazilian outlets such as CNN Brasil framed the discovery around the contrast with everyday stellar colours, emphasising the Warwick team's point that normal stars are practically only orange, white or blue, and highlighted forecasts that spectroscopic surveys could soon reveal 10 to 20 similar green white dwarfs.
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