Astronomers have spotted a newborn planet orbiting around a young star that took only 3 million years to form – quite fast in cosmological terms – in a discovery that challenges current understanding of the speed of planet formation .
This baby world, which has about 10 to 20 times the mass of Earth, is one of the youngest planets ever discovered beyond our solar system – called an exoplanet. It resides with the remains of a disk of dense gas and dust orbiting the host star – called a protoplanetary disk – that provided the material for the planet’s formation.
The star it orbits is expected to be a stellar type known as an orange dwarf, which is less hot and less massive than our Sun. The star has about 70% the mass of the Sun and about half its luminosity. It is located about 520 light years from Earth in our galaxy. A light year is the distance that light travels in one year, 5.9 trillion miles (9.5 trillion km).
“This discovery confirms that the planets may have formed in a cohesive form within 3 million years, which was previously unclear because Earth took 10 to 20 million years to form,” said Madison Barber, a graduate student in the department of physics and astronomy at the university. Were engaged.” of North Carolina in Chapel Hill and lead author of the study published this week in the journal Nature.
“We don’t really know how long it takes for planets to form,” said Andrew Mann, a UNC astrophysicist and co-author of the study. “We know that giant planets must form faster than their disks are destroyed because they require so much gas from the disk. But it takes 5 to 10 million years for the disk to be destroyed. So do planets Is formed in 1 million years?
The planet, named IRAS 04125+2902 b and TIDYE-1b, orbits its star every 8.8 days at about one-fifth the distance that separates Mercury, our solar system’s innermost planet, from the Sun. Its mass lies between Earth, the largest of the rocky planets in our solar system, and Neptune, the smallest gas planet. Its density is less than that of Earth and its diameter is about 11 times larger. Its chemical structure is not known.
Researchers suspect that the planet formed away from its star and then moved inward.
“It is difficult to form large planets close to the star because the protoplanetary disk moves away fastest from those closest to the star, which means there is not enough material to form a large planet that closes so quickly,” Barber said. “
The researchers discovered this using the “transit” method, which observes the drop in brightness as the planet passes in front of the host star, from the perspective of a viewer on Earth. It was found by NASA’s Transiting Exoplanet Survey Satellite, or TESS, space telescope.
“It is the youngest known transiting planet. It is comparable to the youngest planets known,” Barber said.
Exoplanets that have not been detected using this method are sometimes imaged directly using telescopes. But these are typically massive, about 10 times larger than Jupiter, the largest planet in our solar system.
Stars and planets are formed from clouds of interstellar gas and dust.
“To form a star-planet system, a cloud of gas and dust will collapse and rotate into a flat atmosphere, with the star at the center and a disk around it. Planets will form in that disk. The disk will then begin to collapse The inner region near the star,” Barber said.
“It was previously thought that we would not be able to find a transiting planet at such a young age because the disk would be in the way. But for some reason about which we are not sure, the outer disk has become distorted, leaving an ideal window “To the star and allows us to detect transits,” Barber said.
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