Astronomers discover the first-ever green star, plus the reddest 'white dwarf' ever seen

Scientists have discovered the first-ever green star, as well as the reddest white dwarf ever seen, according to new research. White dwarfs, the dense, cooling cores left behind after low- to medium-mass stars exhaust their fuel, are known for their moniker deriving from their initial appearance as either white or pale blue. However, this study, published in the journal RAS Techniques and Instruments, suggests that these stars exhibit a wider range of colors, including pink, green, cyan, purple, and yellow.

The color variations are attributed to the higher density of white dwarfs compared to main-sequence stars. Cooler white dwarfs, with a density of about 1 gram per cubic centimeter, interact with trace elements like carbon, calcium, and sodium in their helium plasma, absorbing light across a broader spectrum. This alters their appearance, deviating from the typical orange, white, and blue hues associated with perfect radiators.

One of the intriguing findings is the discovery of WD J1330+6435, a green star containing rocky material. The green hue is a result of calcium, lithium, and sodium traces in its atmosphere, which absorb the orange part of the spectrum, leaving a ghostly green glow. This unique color is so extraordinary that it appears like something from science fiction.

Another remarkable star identified is WD J1011+2845, the reddest white dwarf ever observed. Located roughly 48 light-years away, this star exhibits a deep salmon-pink glow due to the presence of carbon molecules near its surface. The carbon molecules obstruct other wavelengths, causing the star to appear deep pink. These discoveries indicate that there may be many more colorful stellar remnants scattered throughout the universe than previously imagined.