British researchers have found that the dense atmospheres of white dwarfs can give them a green, pink, purple or blue glow, ScienceDaily reports, according to infohub.kz.
Astronomers at the University of Warwick have discovered the first star that would appear genuinely green to the human eye. The object of the study was a cooling white dwarf, WD J1330+6435, with a temperature of about 4,000 degrees Celsius.
The scientists modelled how the color would be perceived, taking into account the characteristics of human vision, and found that this dead stellar remnant glows with a pistachio-green hue. The green color arises from traces of sodium, calcium and lithium that entered the star's atmosphere when its former planetary system was destroyed. The high density of the atmosphere strengthens the absorption of the orange part of the spectrum by sodium, leaving only a ghostly green emission.
The results, published in the journal RAS Techniques and Instruments, showed that the chemical composition of a white dwarf's atmosphere can radically alter its appearance. The study's authors estimate that roughly one in 30 white dwarfs in the Universe has an unusual color, including vivid pink, yellow or deep red tones.
"The presence of sodium in the atmosphere of this white dwarf absorbs the orange part of the spectrum, leaving a green glow. Imagine standing on a planet and looking at a green star. It looks like a frame from a science fiction film," said the lead researcher, Mark Hollands.