Astronomers Discover A White Dwarf Star That Could Look Green To Human Eyes

Astronomers have identified a white dwarf star that could appear green to human eyes, according to a new study. The finding shows that these stars, which are the remains of stars like the Sun, can have different colours because of the elements present in their outer layers. According to the study's lead author, Mark Hollands, an astrophysicist at the University of Warwick in England, most normal stars appear orange, white or blue. However, some white dwarf stars can show unusual colours because of the physical conditions in their outer layers, reported CNN.

These colour differences are linked to the interaction between helium in the stars' atmospheres and small amounts of other elements. The elements present can vary depending on the material that has interacted with each star during its lifetime.

The study found that elements such as iron, magnesium and sodium, which are commonly found in rocks, can be present on the surfaces of white dwarfs. This material may come from a former planetary system or an asteroid that moved too close to the star.

Hollands told CNN that such an asteroid can break apart into dust and debris, which then fall onto the white dwarf and mix with its outer layers. By studying these elements, scientists can learn about the chemical makeup of rocky material.

Adam Burgasser, a professor of astronomy and astrophysics at the University of California San Diego, said that studying white dwarfs can help scientists understand the elements that made up planets and how those planets formed.

For the study, Hollands examined 151 known white dwarf stars located within 20 parsecs, or around 65 light-years, of Earth.

The green star contains calcium, sodium and lithium as its main elements. Another white dwarf appeared almost salmon pink because of a high concentration of carbon molecules, Hollands said.

Scientists cannot directly see these white dwarfs from Earth. Instead, Hollands calculated their colours using data from their spectra. A spectrum is like a fingerprint created when starlight is separated into different wavelengths, similar to how a prism splits sunlight into a rainbow.

Agnes Kim, an astrophysicist and professor of physics at Penn State Scranton, who was not involved in the study, said that connecting the spectrum of a star to the colour visible to human eyes brings physics and biology together.

She also noted that the study offers an interesting way to understand how these distant objects might appear to people.

Burgasser added that the method used to classify white dwarfs according to their temperatures and atmospheric properties could be useful for future research.