Hot, metallic, Earth-sized planet with a density similar to Mercury detected 339 light years away and characterized by a global team of astronomers, including the University of Warwick
K2-229b is 20% larger than Earth but has a mass 2.6 times greater – and a dayside temperature of over 2000°C
Discovering details about far-flung planets across the universe gives us more clues as to how planets in our own solar system formed
A hot, metallic, Earth-sized planet with a density similar to Mercury – situated 339 light years away – has been detected and characterised by a global team of astronomers, including the University of Warwick.
Named K2-229b, the planet is almost 20% larger than Earth but has a mass which is over two-and-a-half times greater –and reaches a dayside temperature of over 2000°C (2330 Kelvin).
It finds itself very close to its host star (0.012 AU, around a hundredth of the distance between the Earth and the Sun), which itself is a medium-sized active K dwarf in the Virgo Constellation. K2-229b orbits this star every fourteen hours.
Using the K2 telescope, Dr. Armstrong and colleagues employed the Doppler spectroscopy technique – also known as the ‘wobble method’ to discover and characterise this faraway planet.
The astronomers knew the planet was there due to dips in the light from its host star as it orbited, periodically blocking starlight.
They then calculated the size, position, and mass of K2-229b by measuring the radial velocity of the star, and finding out how much the starlight ‘wobbles’ during orbit, due to the gravitational tug from the planet, which changes depending on the planet’s size.
The dense, metallic nature of K2-229b has numerous potential origins, and one hypothesis is that its atmosphere might have been eroded by intense stellar wind and flares, as the planet is so close to its star.
Another possibility is that K2-229b was formed after a huge impact between two giant astronomical bodies in space billions of years ago – much like the theory that the Moon was formed after Earth collided with a body the size of Mars.
Discovering details about far-flung planets across the universe gives us more clues as to how planets in our own solar system formed. As K2-229b is similar to Mercury, knowing more about the former can potentially reveal more about the latter.