© University of Warwick/Dr Mark Garlick
Astronomers have discovered the remains of one of the oldest planetary systems in our galaxy. Evidence for this is provided by 2 white dwarfssince when 90 And the 120 light years away far from earth. You should more 10 billion years be old.
White dwarfs are the cores of extinct stars. These were not massive enough to explode in a supernova and turn into a black hole or neutron star. Instead, they have lost their outer shell and are now beginning to cool. They have high density but low illumination.
10.7 billion years
Researchers University of WarwickUnited Kingdom, has created 2 models of white dwarfs from the Space Telescope Jaya It was discovered. Through simulations, they wanted to know how long it took the cores to cool down. For this they used data from GAIA and Dark Energy Survey and spectrum device.X shooter” In the European Southern Observatory (ESO).
The investigation revealed that the star WDJ2147-4035 previously 2.5 solar masses It was heavy and about 10.7 billion years old is. Where 10.2 billion years It cools like a white dwarf. shines reddish It consists of Sodium, lithium and potassium And the carbon. This makes it the oldest white star yet discovered.
The second star WDJ1922+0233, a little smaller. It was chilling 9 billion years far. However, his exact age could not be determined. shines bluedue to its unusual atmosphere A mixture of helium and hydrogen lies.
The oldest system of the Milky Way
debris in Atmosphere Red WDJ2147-4035 from an ancient planetary system. Scientists wrote that it survived the star’s transformation into a white dwarf, but was then swallowed by the white dwarf. This makes it the oldest planetary system in the world Milky Way.
“These metal-polluted stars are not unique, there are other systems with Earth-like planets. 97 percent All stars become white dwarfs. Because they are so ubiquitous, it is very important to understand them,” says the study leader Abigail Elms in the current situation. They were formed from the oldest stars in our galaxy, and therefore contain information about how the first planetary systems formed.
In fact, astronomers can use minerals to understand what quantities were present in planets that were “devoured” by the white dwarf. In the case of WDJ1922 + 0233, this is clear: here you can find yourself Sodium and calcium And the potassium. From the quantity, the team deduces that a planet has devoured its crust with a composition and mass similar to Earth’s.
With the reddish WDJ2147-4035, the discovery remains ambiguous. “The fertile planetary debris is rich in lithium and potassium and is unlike anything in our solar system. The white dwarf because metal impuritiesfor him very cool surfaceHis old age and the fact that he magnetic Extremely rare,” says Elms.
At the time these stars were forming, there were fewer metals in the universe. Minerals are formed by giant stellar explosions and in star formation. The researchers said the two white dwarfs will thus provide a glimpse into how planetary systems formed in an environment low in metal but rich in gas. The results of the study have been published in the journal Monthly Notices of the Royal Astronomical Society released.
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