A team of astronomers has found that planet formation in the young solar system began much earlier than previously thought.
According to the study, the building blocks of the planets began to grow at the same time as their parent star.
The study, which was conducted on some of the oldest stars in the universe, indicates that the building blocks of planets such as Jupiter and Saturn began to form while the young star (now called the Sun) was growing.
It was previously thought that planets form only when a star reaches its final size, but the new study, published in the journal Nature Astronomy, indicates that stars and planets “grow” together.
The study, led by the University of Cambridge, changes our understanding of how planetary systems, including our own solar system, form, potentially solving a major astronomy puzzle.
Lead author of the study, Dr Amy Bonsor from the University of Cambridge’s Institute of Astronomy, said: “We have a pretty good idea of how planets form, but one of the prominent questions we asked was when they form: does planet formation start early, when the parent star is still growing, or later. millions of years?”
To answer the question, the researchers studied the atmospheres of white dwarf stars – the old, fading remnants of stars like our Sun – to investigate the building blocks of planet formation.
“Some white dwarfs are amazing laboratories because their atmospheres are almost like a celestial graveyard,” said Dr Bonsor.
And while the planets’ interiors are out of reach of telescopes, a special class of white dwarfs – known as polluted systems – contain heavy elements such as magnesium, iron and calcium in their normally clean atmosphere.
It is assumed that these elements came from small bodies such as asteroids left behind by the formation of planets, which collided with white dwarfs and burned in their atmospheres.
Therefore, observations of polluted white dwarfs can probe the shattered interiors of these asteroids, giving astronomers a direct insight into the conditions under which they formed.
The scientists analyzed observations from the atmospheres of regarding 200 polluted white dwarfs from nearby galaxies.
According to their findings, the mixture of elements seen in the atmospheres of these white dwarfs can only be explained if many of the original asteroids melted at once.
This would have caused the heavy iron to sink into the core while the lighter elements float to the surface.
This process, known as differentiation, is what made Earth’s iron-rich core.
Dr Bonsor explained: “The cause of the melting can only be attributed to very short-lived radioactive elements, which were present in the early stages of the planetary system but decay in just a million years. In other words, if these asteroids melted with something that existed only for a very short time at the dawn of the planetary system, the planet formation process should start very quickly.”
The study indicates that the picture of early formation is likely to be correct, which means that planets such as Jupiter and Saturn have plenty of time to grow to their current sizes.
Bonsor added: “This is just the beginning – every time we find a new white dwarf, we can gather more evidence and learn more regarding how planets form. We can track elements like nickel and chromium, and say how big the asteroid was when its iron core was formed. It’s amazing that we’re able to investigate processes like this in exoplanet systems.”
Source: The Independent
