Fragments of planets with crusts akin to Earth have recently been discovered in the atmospheres of four white dwarf stars nearby by astronomers at the University of Warwick.
According to Knowridge Science Report, the discovery provides a glimpse of planets "that may have once orbited them up to billions of years back."
Such crusts from the rocky planets' outer layers akin to Earth and Mars and could provide astronomers with greater understandings into the planets' chemistry that these so-called dying stars once hosted.
The discovery came out today in the Nature Astronomy journal, and it includes one of the "oldest planetary systems" observed by astronomers so far.
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More Than a Thousand Nearby White Dwarf Stars Studied
The research team from the University of Warwick evaluated data from the European Space Agency's Gaia telescope of more than a thousand nearby white dwarf stars when they came across an uncommon indication from one specific white dwarf.
They were also given financial backing from the European Research Council and the Science and Technology Facilities Council or STFC.
To assess the light from the star at different wavelengths, the astronomers used spectroscopy, enabling them to identify elements in the atmosphere of the stars, are absorbing light at various colors, and identify "what elements those are and how much is present.
Moreover, the researchers also inspected the 30,000 white dwarf spectra from the Sloan Digital Sky Survey, which came out over the past two decades.
Crust Similar to Asteroids
As indicated in the study, the amount of crust discovered is the same as that of the asteroids seen in the solar system, leading the researchers to believe that what they see roughly around all four stars is a substance broken off from a planet instead of the whole planet itself.
Past observations of white dwarfs have shown evidence of substance from the internal core and the mantle of planets, although no absolute evidence of crust material.
The crust is a small fraction of the mass of a planet, as well as the elements identified in this research are only identifiable when the star is quite cool.
Meanwhile, white dwarfs are said to be in their lifecycle's dying phase, as they have "burnt out their fuel and cool over billions of years."
The said four white dwarfs are believed to have burnt out their fuel up to 10 billion years back and could be among the oldest white dwarfs formed in the galaxy.
The 'Rocket Planet Formation'
Dr. Hollands adds: "As we understand it, rocky planet formation happens similarly in different planetary systems.
According to Dr. Mark Hollands, the study's lead author from the University of Warwick's Department of Physics, at first, they are formed from comparable material composition to the star. However, as time goes by, those materials separate "and you end up with different chemical composition" in various parts of the planets.
He added that they could see that the said three objects have gone through differentiation at some point, where the composition is distinctive to the star's starting composition.
Lastly, it is now well and clearly understood that most normal stars like the Sun harbor planets. However, now, there is the opportunity to look at the frequency of various material types.
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