Scientists discover remnants of a mysterious solar system in deep space

Scientists discover remnants of a mysterious solar system in deep space

We know space is teeming with mystery. Adding to the intrigue, astronomers recently discovered an ancient solar system that is far different from our cosmic home.

About 90 light-years away, researchers spotted a white dwarf star over 10 billion years old — meaning the remaining hot core of a dead star similar to sun — that’s surrounded by a graveyard of shattered bits of planets called planetesimals. The faint star has attracted debris from these objects. But this solar system is unlike anything around us. It is abundant in elements such as lithium and potassium. Most importantly, there are no planets our solar system have such a composition.

Why this ancient solar system was in our early Milky way galaxy so different? How did it become rich in these materials, which were rare at the time?

“It’s a complete mystery,” Abigail Elms, a postdoctoral researcher at the University of Warwick who studies white dwarfs, told Mashable. The research was published this week in the scientific journal Monthly Notices of the Royal Astronomical Society.

As noted above, this solar system is old. This means that the white dwarf (called WDJ2147-4035) and the surrounding solar system formed and died before the sun and Earth were even born. In fact, the pieces of former planets around WDJ2147-4035 are the oldest planetesimals ever discovered in our galaxy around a white dwarf, Elms noted.

How do astronomers know what this archaic solar system was made of?

They discovered this white dwarf and another of a similar age using an observatory in space called Gaia. As it orbits the sun, this distant spacecraft maps stars and galaxies in space. After spotting these white dwarfs, the researchers turned to an instrument called the “X-Shooter” located at a high altitude in Chile to find out what is present and what is not present in the stars’ atmospheres (the X-Shooter is a type of extremely valuable an astronomical instrument called a “spectrometer”). In WDJ2147-4035, they found that chemicals such as lithium, potassium, and sodium had accumulated — or been attracted by gravity and accumulated around — the ancient star. White dwarfs are made of hydrogen or helium, so the rocky remnants of planets are responsible for supplying the other unique elements, the researchers concluded (by running simulations of the evolution of this solar system).

Artist’s concept of chunks of planets (planetesimals) orbiting white dwarf stars.
Credit: University of Warwick / Mark Garlick

Interestingly, the other white dwarf (WDJ1922+0233) they found was significantly different from the mystery one. It’s more familiar. They found that this star has attracted planetary debris that is similar to Earth’s rocky crust. So while one solar system remains an anomaly, the other shows that Earth is not so unique in the cosmos: there are others solar systems there somewhat like this.

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However, these two solar systems are full of graveyards of former planets. Over 95 percent of stars, like the sun, evolve into white dwarfs. Towards the end of their lives, they expand into colossal red giants, destroying or destroying nearby objects. As our sun expands, it will swallow up planets like Mercury, Venus, and perhaps even Earth before shedding its outer layers. Red giants will leave behind relics of shattered planets and moons. The remnant star itself will be a white dwarf.

This is our cosmic destiny. Just not for a long, long, long time.

“Our sun will evolve into a white dwarf in approximately 5 billion years,” Elms said.

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