Astronomers have detected the youngest exoplanet ever discovered, orbiting incredibly close to a distant star. The discovery of the infant planet, known as K2-33b, could allow astronomers to gain a clearer understanding of the earlier stages of planetary formation.

Prolific planet-hunting telescopes such as Kepler and Hubble have identified over 3,000 alien worlds orbiting far-flung stars. The vast majority of these exoplanets are discovered around stars that formed over a billion years ago, meaning that the planets themselves are generally in the mid-late stages of their lives.


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Whilst the study of these exoplanets has revealed a great deal regarding their evolution, the relative absence of youthful planets such as K2-33b has prevented astronomers from unravelling many of the mysteries that persist regarding the early stages of planetary life cycles.

The orbit of K2-33b as compared to that of Mercury (Credit: NASA/JPL-Caltech)

K2-33b was first detected as a periodic dip in light from its parent star, created as the exoplanet passed between the stellar body and the Kepler Space Telescope. Follow up observations by the W. M. Keck Observatory, Hawaii, and infrared data collected by the Spitzer Space Telescope confirmed that the system still plays host to a depleted protoplanetary disk, meaning that planetary formation had, at least in astronomical terms, only just concluded.

"Our Earth is roughly 4.5 billion years old," states Trevor David of Caltech in Pasadena, lead author of a study on the discovery. "By comparison, the planet K2-33b is very young. You might think of it as an infant." David is a graduate student working with astronomer Lynne Hillenbrand, also of Caltech.

It is estimated that K2-33b, which is believed to be slightly larger than Neptune, is between 5-10 million years old, making it the youngest exoplanet discovered to date. Data collected by the Earth and space-bound observatories revealed that the exoplanet orbits very close to its parent star, a characteristic that does not conform with current theories on planetary formation.

Ordinarily, it is thought that a body as massive and young as K2-33b should form in a fairly distant orbit from its parent star, yet the newly discovered exoplanet was observed 10 times closer than Mercury orbits from our Sun. Astronomers are at a loss to explain the unusual orbit.

Much older planets had been observed in ultra-close orbits, but the migration process is thought to have taken hundreds of millions of years, and so could not explain the orbit traversed by K2-33b. It is therefore possible that the planet was simply created in its current orbit through some process unaccounted for by the current models for planetary formation.

A paper on the findings has been published online in the journal Nature.

Source: NASA

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