Astronomers Spot First Ever Green Star
Scientists discover first green white dwarf
Translated by Qiyas from الراي — Original source
Russia Today – Astronomers have discovered the first green star ever, in a study showing that white dwarfs can exist in a variety of colors.
It was previously believed that white dwarfs—the remnants left behind by stars like our Sun after they die—behave in the same way. However, new research indicates that, despite their name, white dwarfs can actually appear in a wide range of colors.
According to the study’s authors, who found the first example of its kind, if one could approach these stars, they would appear pink, sky-blue, yellow, purple, and even green.
Mark Hollands of the University of Warwick, who led the research, said that most stars, including most white dwarfs, behave like “perfect radiators” (an idealized body that absorbs and emits radiation with maximum efficiency at all wavelengths). Thus, their color is determined almost entirely by temperature. However, no one had really explored what might be possible for white dwarfs.
He added that these extremely dense stars can produce colors that no one had anticipated, with some truly surprising him. Scientists note that white dwarfs are unusual because of their extreme density: they are millions of times denser than the Sun’s outer atmosphere, with a density roughly equivalent to that of water. This density means that any elements present can interact with the plasma in the white dwarf, absorbing light across many more colors. Consequently, these white dwarfs are not perfect radiators; instead, they reflect the chemical composition of the surrounding material.
No white dwarf is close enough for us to see its color directly. Instead, scientists in the new study determined its color using data from its spectrum—the “fingerprint” obtained by splitting the star’s light into its various wavelengths. They then processed the data through a model simulating human vision to identify the actual color.
The white dwarf WD J1330+6435, with a temperature of around 4,000 degrees Celsius, attracted scientists’ attention because it had accreted rocky material from its former planetary system, adding calcium, lithium, and sodium to its atmosphere and giving it a pale green glow. It is the first star of this color ever observed.
