Astronomers have identified the first white dwarf star, dubbed WD J1330+6435, that exhibits a “ghostly green glow” resulting from consuming the rocky remnants of dead planets. This celestial discovery, made by a team from the University of Warwick, was announced last week.
Located approximately 280 light-years from Earth in the Milky Way, WD J1330+6435 can be faintly observed in the constellation Draco. Astrophysicist Mark Hollands described the find, saying, “It feels like something out of science fiction.”
This discovery marks a significant milestone, as it is the first documented instance of a white dwarf star exhibiting a green hue. Researchers revealed that the star’s color can change based on the elements it absorbs, including carbon, calcium, and sodium.
Hollands explained that most stars, including typical white dwarfs, emit light based on their temperature. He noted, “Cool stars look orange, and hot stars appear pale blue,” stating that the team had not previously explored the potential for different colors in white dwarfs. “It turns out these incredibly dense stars can produce colors nobody expected, and some of them genuinely surprised me,” he said.
The sodium present in the atmosphere of WD J1330+6435 absorbs orange wavelengths of light, leading to its distinctive green glow. Hollands remarked, “Imagine standing on a planet and looking up at a green star.”
White dwarfs are remnants of stars that have exhausted their nuclear fuel. As they deplete their energy, these stars shed their outer layers and can consume nearby planets and other matter, leading to the nickname “zombie” star. The rocky material absorbed by WD J1330+6435 contains calcium, lithium, and sodium, which contributed to its unique glow.
In addition to the discovery of the green star, astronomers also reported on another white dwarf located about 48 light-years away, identified as WD J1011+2845. This star has been characterized as potentially the reddest star ever observed, exhibiting a salmon-pink hue due to carbon being brought to its surface through a deep convection zone.
Researchers estimate that only 3 percent of white dwarfs exhibit such vibrant colors, with Boris Gänsicke from the University of Warwick stating that while “one in thirty might not sound like a huge fraction, across the entire population of white dwarfs in the universe, that is still a lot of oddly colored stars out there.” He added that, on average, most white dwarfs appear white.
Looking ahead, the Sun is expected to enter its white dwarf phase in approximately 5 billion years after exhausting its hydrogen and engulfing the inner planets of the solar system.
