White Dwarfs Could Glow Green and Other Unexpected Colors, New Research Suggests

Astronomers have long assumed a star's color is set by its temperature, but new research says dense white dwarfs can break that rule.

Cool stars look orange, stars like the sun look white and the hottest stars glow pale blue, and white dwarfs were assumed to follow the same rule. New research suggests these stellar remnants could instead glow in a range of colors including green, pink, cyan, yellow and purple.

Team leader Mark Hollands of the University of Warwick said most white dwarfs behave like perfect radiators whose color is set almost entirely by temperature, but that nobody had looked into what else might be possible.

Why density matters

White dwarfs form when sun-sized stars run out of fuel and their cores collapse, leaving matter far denser than the sun's surface. In those conditions, elements such as carbon, calcium and sodium can interact with the surrounding dense helium plasma and absorb light across a wider range of colors. Space.com reports the research also considers white dwarfs that consume their rocky planets, which is why the story links a green glow to the sun's far-future fate.