Earth and other planets in our solar system have existed longer than previously thought, according to a new study of asteroid debris in a distant star system.
Published in Nature Astronomy on November 14thResearchobserved the oldest stars in the universe and suggests that stars and planets grew together. Previously it was thought that planets would not form until the star reached its maximum size.
The sun formed from a gas cloud 4.6 billion years ago and the planets formed around it.
“We know quite well how planets formed, but one question that remains is ‘when?’ Was it while the parent star was still growing, or was it millions of years later?” says Dr Amy Bonser of the Cambridge University Institute of Astronomy.
The antennas of the Atacama Large Millimeter and Submillimeter Interferometer (ALMA) radio telescope. Located on the Chajnantor plateau in San Pedro de Atacama, Chile, about 1,500 kilometers north of Santiago (Getty Images)
Using the Atacama Large Millimeter-Submillimeter Interferometer in Chile, researchers probed the atmosphere of a white dwarf (the remnant of a dead sun-like star) looking for planetesimals, the building blocks of planets. “Some white dwarfs surprised the lab because their tenuous atmospheres were like graveyards in the sky,” says Bonser.
The white dwarfs studied are unique because their atmospheres are contaminated with heavy elements such as magnesium, iron and calcium. According to the authors, these elements should come from asteroids born during the formation of the planets that subsequently collided with white dwarfs and melted in their atmospheres.
According to the paper, the process by which lighter elements float to the surface and iron sinks to the core is why Earth has an iron-rich core.
Planet formation is generally believed to have begun in rings of hydrogen, helium, and particles of ice and dust orbiting young stars. The dust particles combine to form planetesimals, which grow into asteroids or planets over time.
This study suggests that planetesimals formed almost immediately. “If these asteroids were merged into something that only existed for a short time early in the planetary system, the planet-forming process must start very quickly,” Bonser said. “Our work complements the growing consensus in the field that planet formation started early and that the first bodies formed at the same time as stars.”
Wishing for clear skies and big eyes.
