Monster planet found around dwarf star

A“monster” planet, which should in theory not exist, has been discovered orbiting a faint dwarf star far, far away, surprised astronomers said yesterday.

The existence of the gassy giant challenges longstanding theories that such a big planet — about the size of Jupiter — cannot be formed around a star so small. The star has a radius and mass about half that of the sun.

Theory had predicted that small stars can form rocky planets, “but do not gather enough material together to form Jupiter-sized planets”, Britain’s Royal Astronomical Society said in a statement.

Planets are thought to form as gas and dust left over from massive galactic explosions, and swirling in disks around newborn stars, clump together to form bodies.

The planet was discovered by the Next-Generation Transit Survey (NGTS), based in Chile’s Atacama Desert. The project gave its name to the star NGTS1, and dubbed the planet NGTS-1b. The “b” signifies it is the first planet found around this star.

The survey uses an array of 12 telescopes to scour the sky and identify dips in light emitted by stars — a sign that a planet is moving in front of the star as perceived from Earth.

“The discovery of NGTS1b was a complete surprise to us — such massive planets were not thought to exist around such small stars,” said Daniel Bayliss from the University of Warwick, a lead author of the study accepted for publication in the science journal Monthly Notices of the Royal Astronomical Society.

“The planet is about 25 per cent the radius its host star. This makes is very large compared to its host star!” Bayliss said.