They can glow white, yellow, red and blue, but never green \u2013\u00a0or so we thought.<\/p>\n
A team of astronomers say their study demonstrates the myriad of different colours present in stars across the Universe including pink, purple and green.<\/p>\n
More amazing Chandra observations<\/p>\n
![\"Artist's](\"https:\/\/www.newsbeep.com\/nz\/wp-content\/uploads\/2026\/10\/uy-scuti-star.jpg\")
Credit: Dzika Mrowka<\/p>\n
![\"Artist's](\"https:\/\/www.newsbeep.com\/nz\/wp-content\/uploads\/2026\/10\/green-star.jpg\")
Artist’s impression of cool white dwarf WDJ1330+6435, which has accreted sodium-rich rocky material from its planetary system into its atmosphere. Its atmospheric density causes it to glow green. Credit: Mark A. Garlick\/University of Warwick
\nWhy stars glow different colours<\/p>\n
The team behind the study say their observations show that white dwarf stars<\/a> \u2013\u00a0the dense husks left behind when ageing stars run out of fuel \u2013\u00a0can glow in a range of colours.<\/p>\n In essence, stars glow different colours due to their temperature, from the cool, red glow of older stars to the scorching pale blue of new-born stars.<\/p>\n It was thought that white dwarf stars followed the same rule. Indeed, white dwarfs are so-called because they’re generally seen to glow a fiercely hot-white.<\/p>\n But astronomers say orange, white and blue are not the only colours a star can be.<\/p>\n Their study shows that, if we could observe certain white dwarf stars up close, we’d see them glow yellow, purple, pink, cyan and green.<\/p>\n “Most stars, including most white dwarfs, behave like \u2018perfect radiators,\u2019 so their colour is set almost entirely<\/a> by temperature. But nobody had really looked into<\/a> what else might be possible for white dwarfs,” says Dr Mark Hollands, an astronomer at the University of Warwick in the UK.<\/p>\n “It turns out these incredibly dense stars can produce colours nobody expected, and some of them genuinely surprised me.”<\/p>\n The team behind the study say it’s all down to the density of the stars.<\/p>\n The coolest white dwarf atmospheres reach about 1 gram per cubic centimetre, which is about the same density as water and millions of times as dense as our Sun’s photosphere.<\/p>\n At this density, trace elements like carbon, calcium and sodium interact with the surrounding helium plasma.<\/p>\n That makes the elements absorb a wider range of colours of light than they would at lower densities.<\/p>\n There are no white dwarf stars close enough for the team to have observed them directly, so instead they calculated the colours using the stars’ spectra.<\/p>\n A spectrum is the fingerprint produced when light from a star is split into its constituent colours.<\/p>\n Astronomers can learn a lot about the chemistry of celestial objects by observing them in this way.<\/p>\n The team ran spectra through a model of human colour vision to find out what colour each star would appear to the human eye.<\/p>\n The team found that each star fell into distinct colour groups depending on what’s in its atmosphere.<\/p>\n Carbon-rich white dwarfs are typically pink or purple.<\/p>\n White dwarfs that have swallowed debris from asteroids and comets tend to be more yellow.<\/p>\n Cooler white dwarfs with mixed hydrogen and helium atmospheres are often cyan or pale blue.<\/p>\n Star WD J1330+6435, which is about 4,000\u00b0C (7,200\u00b0F), has swallowed rocky debris from its orbiting planets.<\/p>\n That, say the team, has enriched its atmosphere with calcium, lithium, and sodium, causing it to glow green \u2013\u00a0according to models.<\/p>\n They say no other star has ever been ‘credibly’ reported as green, making it the first known genuinely green star in the Galaxy.<\/p>\n “The traces of sodium in the atmosphere of this white dwarf absorb the orange part of the spectrum, leaving behind a ghostly green glow,” says Dr Hollands.<\/p>\n “Imagine standing on a planet and looking up at a green star. It feels like something out of science fiction.”<\/p>\n The astronomers say they’ve also found what could be the reddest star ever recorded: WD J1011+2845, a white dwarf star 48 lightyears from Earth.<\/p>\n This star has a deep convection zone that has brought carbon from its core to its surface.<\/p>\n The carbon molecules distort the star\u2019s light to produce a deep salmon-pink glow.<\/p>\n But white dwarfs are still white (mostly)<\/p>\n The team looked at 151 white dwarfs within about 65 lightyears of Earth.<\/p>\n They say five showed strange colouring, with two glowing yellow and three pink. That could mean one in 30 white dwarfs in the Universe shines with a strange colour.<\/p>\n However, the remaining 146 glow in the warm white of a light bulb which, the team say, corrects a misconception that white dwarfs are typically blue.<\/p>\n “One in thirty might not sound like a huge fraction, but across the entire population of white dwarfs in the Universe, that is still a lot of oddly coloured stars out there,” Professor Boris G\u00e4nsicke, Department of Physics at the University of Warwick.<\/p>\n “Yet if we take the median across a representative population of white dwarfs, we found that the average white dwarf really is white.”<\/p>\n![\"Globular](\"https:\/\/www.newsbeep.com\/nz\/wp-content\/uploads\/2026\/10\/heic1321a-29dcefe-scaled-e1602578090372.jpg\")
Globular cluster M15 contains hot blue and cooler golden stars. Credit: ESA, Hubble, NASA<\/p>\n![\"Artist's](\"https:\/\/www.newsbeep.com\/nz\/wp-content\/uploads\/2026\/10\/WD_00049-2_crop-2048x1170-1.jpg\")
Artist’s impression of a rocky planet orbiting a white dwarf. Credit: W. M. Keck Observatory\/Adam Makarenko
\nWhat makes white dwarfs so colourful?<\/p>\n![\"Simulated](\"https:\/\/www.newsbeep.com\/nz\/wp-content\/uploads\/2026\/10\/star-colours.jpg\")
Simulated images showing the calculated colours of white dwarfs. Credit: Mark Hollands\/University of Warwick
\nThe star that glows green<\/p>\n![\"Cool](\"https:\/\/www.newsbeep.com\/nz\/wp-content\/uploads\/2026\/10\/pink-star.jpg\")
Cool white dwarf WDJ0902+2010 has a deep convection zone that lifts interior carbon to the surface forming carbon molecules that make it appear pink to the human eye. Credit: Mark A. Garlick\/University of Warwick
\nThe reddest star<\/p>\n