Dead stars can glow green and other unexpected colors, study finds
Researchers report that white dwarfs, the dense remnants left by sun-like stars, can display colors beyond what temperature alone predicts. In particular, sodium in a white dwarf's atmosphere can absorb orange wavelengths and leave a green tint. The work suggests these dead stars may appear in hues such as green, pink, cyan, yellow, and purple, especially if they consume rocky planetary material.
White dwarfs are the collapsed cores left when stars about the sun's mass exhaust their fuel. Their material is extremely dense, and in that environment elements such as sodium, calcium, and carbon can absorb light differently than they would in thinner gases. Sodium specifically can remove orange wavelengths, allowing a green appearance.
The study suggests these remnants may fall into color groups based on atmospheric chemistry, not temperature alone. If a white dwarf pulls in rocky planetary debris, its spectrum and apparent hue could shift toward green, pink, cyan, yellow, or purple. The researchers note that distance has kept astronomers from seeing such colors directly.
This result could affect how astronomers, educators, and science communicators explain stellar color, since temperature may no longer be the sole guide for white dwarfs. Observers might use atmospheric chemistry to interpret unusual hues, while the public may find green or pink dead stars more memorable. Practical consequences for everyday life are likely limited, but the finding may enrich astronomy outreach and future observational priorities.