Astronomers have identified the oldest remains of planets in the Milky Way . And , they are comparatively nearby , just 90 light - geezerhood from Earth . Researchers used observations of white dwarfs to identify those“polluted ” by chunks of planetsand other dust , and found one that has existed for an forecast 10.7 billion year . That ’s over twice the age of our own Earth .
A white nanus is a late point in the evolution of adept like our Sun . Once they can no longer fuse H , star topology contract and ignite helium , forcing them to expand into a ruby-red giant star . Over time , such stars lose their loosely bound out bed , and if they are not monolithic enough to go on to become a supernova , their cores contract into white dwarfs .
planet that used to orbit the original star , before these dramatic transformation , are often offend apart . This planetary debris can then settle onto the blanched dwarf , deepen its alchemy in a fashion that astronomer can measure .
" We ’re finding the oldest leading remnants in the milklike Way that are contaminate by once Earth - comparable satellite . It ’s astonishing to think that this fall out on the scale leaf of 10 billion years , and that those planets drop dead way before the Earth was even take shape , " lead author Abbigail Elms , a graduate researcher at the University of Warwick , said in astatement .
The team identified the “ red ” white midget WDJ2147 - 4035 , estimated to be 10.7 billion years old , which has spent 10.2 billion years as a white dwarf . Among the heavy component present on this star were sodium , atomic number 3 and K , as well as potential carbon . The object is indeed dumbfound , and not just because it ’s polluted .
" The blood-red ace WDJ2147 - 4035 is a mystery as the accrete planetary debris are very lithium and atomic number 19 rich and unlike anything known in our own solar arrangement . This is a very interesting ashen dwarf as its ultra - coolheaded airfoil temperature , the metals polluting it , its old geezerhood , and the fact that it is magnetic , makes it highly rare , " Elms keep .
The team also identified a second polluted white midget , the " gamy " star WDJ1922 + 0233 . Both hotshot are the coldest polluted white dwarfs to date . The composition of the planetary rubble from this second objective is a lot more in line with the continental crust of the Earth . The ashen dwarf appears blue because of a peculiar mixture of helium and hydrogen in its atmosphere .
" When these old stars formed more than 10 billion years ago , the universe was less metal - plenteous than it is now , since metals are form in evolve stars and mammoth prima blowup . The two observed white dwarfs cater an exciting window into planetary organisation in a metallic element pitiable and gas pedal - deep surroundings that was different to the status when the solar organisation was form , " added fourth-year writer Professor Pier - Emmanuel Tremblay , also at the University of Warwick .
More evidence of ancient planets , similar in theme to the Earth , makes us marvel how likely it is that life could have evolved on those worlds . In the particular showcase of WDJ2147 - 4035 , it seems that things move too speedily from star to white nanus , but maybe there are other worlds out there that have survive ( and if there are , where is everyone ? ) .
The study was published inMonthly Notices of the Royal Astronomical Society .
