'Extra hot and young' Earth-sized exoplanet with a ‘lava hemisphere’ discovered

A team of scientists has discovered a new Earth-sized exoplanet in a planetary system previously known for having just two planets. The newly-discovered planet is however extra hot and young. The object, called HD 63433 d, is also tidally locked on its axis, meaning that it has one side which constantly faces its Sun-sized star while the other side endures constant darkness.

The planetary system is believed to be 500 million years old and HD 63433 d exoplanet is known to be the youngest Earth-sized planet closest to the Earth, which is 400 million years old. The planetary system, called HD 63433, is about 10 times younger than our solar system.

Lava hemisphere

Since the exoplanet is tidally locked, experts believe the scorching temperatures on the dayside could be comparable to other lava worlds in the space. The team behind this discovery even thinks that the planet's dayside could be a "lava hemisphere."

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It must be noted that the star in the system is also a G-type star. Such a star has about 0.9 to 1.1 solar masses and an effective temperature between about 5,300 and 6,000 K. Our own star ‘Sun’ is also a G-type star.

How was the exoplanet discovered?

The team of scientists, led by Benjamin Capistrant and Melinda Soares-Furtado, used data from NASA's TESS (Transiting Exoplanet Survey Satellite) to identify a third unknown object in the planetary system. Upon muting signals from the two known exoplanets, the scientists could detect the presence of a third planet during its ‘transit,’ a period when a planet crosses in front of its star, blocking a tiny piece of the starlight.

This allowed them to see an additional signal - a small transit that would reappear every 4.2 days. Upon further investigation, they were able to validate that this was actually a third, smaller planet.

The planet is so close to its star that the temperature on its dayside surface can reach 1,257 Celsius. It is 8 times closer to its star than Mercury is to the Sun. Some scientists even believe the planet lacks a substantial atmosphere.

(With inputs from agencies)