The oldest dead star known to have a system of rocky planets just 90 light-years from Earth has been discovered and offers insights into the formation of worlds that formed nearly 11 billion years ago.
The star is the so-called white dwarf, a stellar corpse whose core has run out of hydrogen fuel. born regularly star 10.7 billion years ago (only 3 billion years after the great explosion), the stellar corpse, named WDJ2147-4035, is one of two white dwarfs contaminated with planetary debris recently discovered in data collected by the European Space Agency. Jaya Galaxy mapping mission.
Although they are not the first white dwarfs Found it piling rubble From an apparent derby to demolishing planets, they are the oldest and thus provide in-depth insights into the composition of planets that formed when the universe was less than 3 billion years old.
In the case of WDJ2147-4035, its former star was greater than the sunbut not huge enough to explode as a file Supernova at the end of his life. Instead, half a million years after its formation, or about 10.2 billion years ago, the hydrogen ran out of fuel for nuclear fusion in its core and swelled to become a star. red giant. It then inflates its outer layers to reveal its inert, helium-rich core – a white dwarf.
As gravitational fields flow as the star evolves through its red giant phase, some orbiting planets have been destroyed or disrupted, while others may be intact survived. In both cases, the perturbations have brought down large amounts of planetary debris that has been orbiting the white dwarf since then.
Astronomers led by Abigail Elms, a doctoral student at the University of Warwick in the UK, used measurements of light spectra from Gaia, scanning dark energy using dark energy camera On the Victor M. Blanco telescope at the Cerro Tololo Inter-American Observatory in Chile, and the X-Shooter instrument on the Very Large Telescope also in Chile, analyzing the chemical composition of WDJ2147-4035 in red, the second white dwarf WDJ1922 + 0233 shown in blue.
The results show an astonishing diversity in planetary structures. Blue WDJ1922 + 0233, which gets its color not from its temperature but through the unusual mixing of gases in its atmosphere helium and hydrogen, appears to be contaminated with substances similar in composition to those in the Earth’s continental crust.
The red WDJ2147-4035 is a puzzle. It is enriched with lithium, potassium, and sodium and temporarily detects an accumulation of carbon on the white dwarf.
“The red star WDJ2147-4035 is a mystery because the accumulating planetary debris is so rich in lithium and potassium and unlike anything known in our solar system,” Elms said.
Either way, the results provide further evidence that rocky planets were able to form abundantly in the distant past, even though heavy elements were less common in Universe Back then, as these items needed to be built by every generation of stars.
“It’s amazing to think that this happened on a 10-billion-year scale, and that those planets died before Earth was even formed,” Elms said.
search (Opens in a new tab) It was published in the November 5 issue of the Monthly Notices of the Royal Astronomical Society.
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