Evrim Yazgin
Cosmos science journalist
A giant planet orbiting a very young star could be the youngest transiting exoplanet found. Its discovery could shed light on how planets form.
More than a dozen exoplanets have been found transiting stars that are 10–40 million years old. For comparison, our Sun is about 4.6 billion years old.
Until now no planets have been found transiting younger stars – probably because they are not fully formed or are obscured by the protoplanetary disc that surrounds young stars.
According to research published in Nature, astronomers have found the youngest transiting planet. The protoplanet is dubbed IRAS 04125+2902 b.
Its host star, IRAS 04125+2902, is just 3 million years old. It’s 520 light-years from Earth.
IRAS 04125+2902 b orbits the star every 8.83 days. The planet has a radius 10.7 times that of Earth and a mass 30% that of Jupiter. The protoplanet is “a possible precursor of the super-Earths and sub-Neptunes frequently found around main-sequence stars”, the authors of the paper write.
“It was previously thought that the detection of a transiting planet in a disk-bearing system was improbable,” the authors add. They say that a special set of circumstances allowed for the transiting IRAS 04125+2902 b to be spotted.
The planet’s orbit is edge-on when viewed from Earth. It is also not obscured by other debris in the outer disc surrounding the star, which is face-on. And the inner disc around the star – to a distance about 20 times that between Earth and our Sun – is depleted of material.
All this means that IRAS 04125+2902 b is visible where other protoplanets of a similar age would not be.
The researchers say the exoplanet provides a unique opportunity to observe planet formation.
“Given its close proximity to Earth and rare configuration, the system is a powerful environment for understanding early formation and migration,” they write.
