Astronomers have identified a star whose atmosphere suggests it might appear green to the human eye. This object is located 284 light-years from Earth. The unusual hue is due to the star's atmosphere absorbing some light, which alters the spectrum of the remaining radiation.
This refers to a white dwarf designated WD J1330+6435. A white dwarf is a dense stellar core remaining after a star has exhausted its fuel and shed its outer layers. These structures are significantly smaller than typical stars but possess extremely high density.
The reason for the unusual coloration lies in the presence of sodium and calcium on the star's surface. These elements absorb specific wavelengths: sodium absorbs some orange light, while calcium absorbs violet light. As a result of this interaction, the remaining light can be perceived by the human eye as green.
It is important to note that this star has not been captured in any images. Due to the great distance, even the most powerful telescopes only display it as a glowing point. Scientists analyzed the object's radiation and modeled what its color would be upon direct observation.
White dwarfs form during the final stage of evolution for stars similar to the Sun. When such stars cease consuming their primary fuel, their outer envelopes are ejected, and the remaining core shrinks to a size comparable to Earth's.
Despite the name, white dwarfs do not always appear white; they can exhibit pink, purple, yellow, or bluish tones. The color of these objects depends on the temperature and chemical composition of their atmospheres. According to the researchers, such anomalous shades are extremely rare—only about 3.4% of studied white dwarfs show a noticeable deviation from white.
The age of this star is estimated to be approximately 8.4 billion years, with it having existed as a white dwarf for about six billion years. The study authors emphasize that they are unaware of any other stars for which green color has been confirmed by equally reliable calculations. The text also mentions that a well-preserved skull of a two-horned rhinoceros was previously found in Greece, dating back about 8–8.5 million years.