University of Warwick astronomers say their green star discovery models WD J1330+6435 as chartreuse green, the first star ever credibly reported that way. Dr Mark Hollands led the work and said the dense stars can produce colours nobody expected.
The study was published in RAS Techniques and Instruments. It says white dwarf stars, the dense remnants left behind when Sun-like stars reach the end of their lives, can appear green, pink, cyan, yellow and purple when their spectra are turned into colours a human eye could register.
Dr Mark Hollands and WD J1330+6435
Hollands said, “Most stars, including most white dwarfs, behave like ‘perfect radiators,’ so their colour is set almost entirely by temperature. But nobody had really looked into what else might be possible for white dwarfs.” He also said, “It turns out these incredibly dense stars can produce colours nobody expected, and some of them genuinely surprised me.”
The team calculated colour from spectra and a model of human colour vision rather than direct viewing. That approach let the researchers assign WD J1330+6435 a chartreuse green appearance even though no white dwarf is close enough for its colour to be seen directly.
RAS Techniques and Instruments
The published work expands the range tied to white dwarf atmospheres. The earliest white dwarf examples found were surprisingly hot and glowed white or pale blue, but the Warwick models say the picture is broader when dense atmospheres are included.
The study says the coolest white dwarf atmospheres can reach around 1 gram per cubic centimetre. In those conditions, trace elements such as carbon, calcium and sodium interact with dense helium plasma and absorb light across a wider range of colours.
WD J1330+6435 colours
WD J1330+6435 sits at roughly 4,000 degrees Celsius and has accreted rocky material from its planetary system. Its atmosphere has been enriched with calcium, lithium and sodium, and the models gave it a chartreuse green appearance.
The same study says carbon-rich white dwarfs are typically pink or purple, white dwarfs enriched with debris from shattered asteroids and comets tend towards yellow, and cooler white dwarfs with mixed hydrogen and helium atmospheres often take on a cyan or pale blue tinge. The result leaves one hard edge to the finding: the study says no other star, living or dead, has ever been credibly reported as green.
For readers following white dwarf research, the practical takeaway is simple. The colour range is no longer limited to orange, white and blue in theory, and WD J1330+6435 now sits as the clearest example of how dense atmospheres can shift what a star would look like in a model. Whether any future observation could ever directly confirm that green appearance remains unanswered.
