According to the Space.com article, astronomers have identified what they describe as the first-ever genuinely green star, a white dwarf designated WD J1330+6435 located about 326 light‑years from Earth. The researchers explain that the star’s green hue arises because sodium in its atmosphere absorbs the orange portion of the visible spectrum, leaving a ghostly green glow. This effect occurs after the white dwarf begins accreting rocky material from a nearby planetary companion, enriching its atmosphere with calcium, lithium and sodium. The article notes that this process likens the dead star to a cosmic zombie that “snacks on its planets”.
The team, led by Mark Hollands of the University of Warwick, examined how the extreme density of white dwarfs allows elements such as carbon, calcium and sodium to interact with dense helium plasma and absorb light across a broader range of colors than they would at lower densities. In the case of WD J1330+6435, the presence of sodium shifts the emitted light toward green. The researchers also studied another white dwarf, WD J1011+2845, situated roughly 48 light‑years away, which exhibits a deep salmon‑pink glow due to carbon carried from its core to the surface by a strong convection zone. This finding suggests that white dwarfs can display a variety of colors beyond the traditional white or pale blue associated with their temperature.
Despite this palette, the article emphasizes that most white dwarfs still appear white. The researchers found that only five of the 151 white dwarfs within approximately 65 light‑years of Earth show extraordinary coloring. Extrapolating from this sample, they estimate that about one in thirty white dwarfs in the universe possesses an unusual hue. Boris Gänsicke, also of the University of Warwick, noted that while this fraction may seem small, it translates to a substantial number of oddly colored stars across the cosmos. Nevertheless, when averaging over a representative population, the typical white dwarf remains white.
The study was published on October 14 in the journal RAS Techniques and Instruments. The article concludes by noting that, to date, no other star—living or dead—has been credibly reported as green, making WD J1330+6435 the first known genuinely green star.