White dwarf colors: why some stars calculate as green, pink, or blue

Most white dwarfs in a nearby sample had a calculated color close to white, but unusual atmospheric absorption can shift a star’s color toward green, pink, cyan, or even vivid blue. The colors come from spectra and models, not resolved photographs of the stars. A peer-reviewed study published October 15, 2026, reported the results for 152 white dwarfs within 20 parsecs of the Sun (the study in RAS Techniques and Instruments).

Most of the nearby sample was close to white

The study’s volume-limited sample contained 152 white dwarfs within 20 parsecs. Five were more than 0.01 in CIE 1960 u–v distance from the Planckian locus, a reference curve for blackbody colors. Those five were two yellow DZ stars and three pink DQpec stars.

Correlated color temperature describes a color by matching it to the temperature of a blackbody with a similar chromaticity. It is not the star’s effective temperature, the physical temperature of its surface. For the 147 stars close to the blackbody locus, 95% had correlated color temperatures between 3,800 and 18,700 K.

Green examples come from separate, deliberately selected groups used to illustrate color variety. They are not among the five outliers in the complete nearby sample, so those examples do not indicate how common green white dwarfs are.

How astronomers calculated the colors

The researchers converted observed spectra and model-atmosphere spectra into estimates of how human vision would perceive their colors. They integrated the spectra across the CIE 1931 XYZ color-matching functions, a standard model of human color response, from 360 to 830 nanometers. They then converted the results to sRGB, the color system used by most displays.

The result is a chromaticity: the color itself, separate from brightness. The researchers scaled display brightness while preserving chromaticity. The white dwarf disks were not resolved, so the study’s colored renderings are calculations, not direct images of colored stellar disks.

Why atmospheres can change a white dwarf’s color

Temperature often explains the color of a star whose spectrum resembles a blackbody. But white dwarf atmospheres can contain broad absorption features that remove light across wide parts of the spectrum. In the extremely dense atmospheres of the coolest white dwarfs, metals such as sodium and calcium, or carbon molecules, can alter the balance of visible wavelengths. The atmospheres can approach a density of 1 gram per cubic centimeter.

Carbon-rich DQ and DQpec stars can show broad C₂ Swan bands, which absorb visible light. In DZ stars, broad absorption from metals including sodium and calcium can shift the calculated color. Selected infrared-faint white dwarfs can appear cyan when hydrogen and helium produce collision-induced absorption that affects visible wavelengths.

Green, pink, and unexpectedly blue examples

The study calculates a chartreuse color for WD J1330+6435, a DZ white dwarf with an effective temperature of 4,240 K. Broad sodium and calcium absorption shape its spectrum. The authors note that the spectrum is somewhat noisy, so its calculated chromaticity could differ slightly from the star’s actual color.

For the DQpec white dwarf WD J1011+2845, whose estimated effective temperature is 4,300 K, distorted C₂ Swan bands suppress much of the light between 400 and 600 nanometers. Most of its visible flux lies above 600 nanometers, producing a calculated salmon-pink hue.

A cool white dwarf can also calculate as blue. WD J2356−2054 is a DZ star with an effective temperature of about 4,000 K. Broad sodium absorption suppresses much of the middle of its visible spectrum, leaving the light around 450 to 500 nanometers more prominent. The study calculates a vivid blue chromaticity for it, outside the blackbody locus, so it has no meaningful correlated color temperature.