A large planet has been spotted orbiting a dwarf star that is just 3 million years old, offering possible clues to how the worlds in our solar system came into being
By Jonathan O’Callaghan
20 November 2024
An artist’s depiction of a system showing its host star, transiting planet and misaligned protoplanetary disc
NASA/JPL-Caltech/R. Hurt, K. Miller (Caltech/IPAC)
A world seen orbiting a 3-million-year-old star about 520 light years from Earth is one of the youngest known planets, offering a window into early planet formation.
The star is an early-stage dwarf star, one much dimmer and less massive than our sun. Its age has been estimated by comparing the intensity and wavelengths of the light it emits with other stars.
Madyson Barber at the University of North Carolina at Chapel Hill and her colleagues studied the star using NASA’s Transiting Exoplanet Survey Satellite (TESS). They found a planet about a third of the mass of Jupiter and 10 times the diameter of Earth by noticing the dip in the star’s light as the planet passed in front.
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The world’s mass and size suggest it is either a large rocky planet, known as a super-Earth, or a small gas giant, called a sub-Neptune, in the process of formation.
We think Earth took between 10 million and 20 million years to form, about 4.5 billion years ago, says Barber. “So it was kind of surprising to see anything at 3 million years.”