- White dwarf stars are known to be, well, white. But that might not always be the case.
- White dwarfs come in a variety of colors, a new study from researchers in the U.K. shows.
- There are even green white dwarfs. No green stars of any kind have been identified before.
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What are the true colors of white dwarf stars?
White dwarf stars are white. But is that always the case? It seems that white dwarfs can actually come in a variety of colors. Researchers at the University of Warwick in the U.K. said on October 15, 2026, that white dwarfs can glow in pink, cyan, yellow, purple and green.
Green is the most surprising, since astronomers have never observed any green stars of any kind. Orange, white and blue are the typical colors of stars we see in the night sky.
White dwarfs don’t shine like typical stars, by the way. They’re the hot, dense cores left over when stars run out of fuel and blow their gases into space. Our own sun will become a white dwarf one day. And now we get to wonder … what color will it be?
The researchers published their peer-reviewed findings in RAS Techniques and Instruments on October 15, 2026.
Density determines the colors of white dwarf stars
Mark Hollands, at the University of Warwick, led the new study. He said:
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. It turns out these incredibly dense stars can produce colors nobody expected, and some of them genuinely surprised me.
So why do white dwarfs come in these varieties of color? It all has to do with the density of the star. The coolest white dwarfs have the highest densities, around 0.036 pounds per cubic inch (1 gram per cubic centimeter). That’s millions of times denser than our sun’s photosphere (its visual surface).
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.
Astronomers can’t observe these colors directly. So the researchers used data astronomers already had. This is the spectrum of the white dwarfs, when their light is split into different wavelengths. Then, the researchers used a model of human color vision. That showed what each star would look like if viewed up close with the human eye.
Rainbow colors of white dwarf stars
The results revealed a wide range of colors. Indeed, white dwarfs were far from being just white. This also depended on what was in the atmospheres of the white dwarfs.
The colors fell into two distinct groups. The first group is carbon-rich white dwarfs. They tend to be pink or purple in color.
However, white dwarfs with atmospheres polluted by debris from asteroids or comets tend to be more yellow.
Meanwhile, white dwarfs that have hydrogen and helium atmospheres are more cyan or blue. This is due to hydrogen molecules colliding with helium atoms in their atmospheres.
1st known green star
One of the biggest surprises involved the white dwarf WD J1330+6435. It is the first documented green star. Astronomers have been on the lookout for green stars, but never confirmed one, until now.
Why is it green? As noted before, it has to do with its density and temperature, and the elements in its atmosphere. Calcium, lithium and sodium give it an overall chartreuse green appearance. Hollands said:
The traces of sodium in the atmosphere of this white dwarf absorb the orange part of the spectrum, leaving behind a ghostly green glow. Imagine standing on a planet and looking up at a green star. It feels like something out of science fiction.
Reddest star ever seen?
Red stars are common. In fact, red dwarfs are the most common stars in our galaxy. But now, the researchers might have identified the reddest star ever seen so far.
White dwarf WD J1011+2845 is 48 light-years from Earth. Why is it so red?
The white dwarf has a deep convection zone on the inside, where carbon is brought to the surface from deep below. Incredibly, the carbon molecules distort the star’s light so much that almost all of it is squeezed into wavelengths beyond 600 nanometers. This produces a deep salmon-pink glow unlike anything seen in an ordinary star, even a red dwarf.
Not all white dwarfs are colorful
Does this mean that all white dwarfs are colorful? No. Most of them are still white. 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.
As for the remaining white dwarfs, the medium color temperature was about 6,800 Kelvin (6500 C or 11,700 F). That looks white to the human eye.
This also shows that most white dwarfs are not typically blue, as is often thought. Hotter, bluer white dwarfs are over-represented in surveys, as they can be seen from farther away.
2-faced white dwarf star
While not a colorful white dwarf, astronomers also said in 2023 that they found a white dwarf, nicknamed Janus, that has two different faces. One side of the star is composed of hydrogen, while the other side is helium. The helium side appears more mottled or bubbly, while the hydrogen side is brighter.
Bottom line: Astronomers in the U.K. have found that the true colors of white dwarf stars can vary greatly. They even found the 1st known green star.
Source: Any colour you like: the diverse chromaticities of white dwarfs
Read more: Life around white dwarfs? Astronomers think it’s possible
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The post Surprising colors of white dwarf stars revealed for 1st time first appeared on EarthSky.