A true giant among dwarfs has been discovered, challenging theories about how planets form
ASTRONOMY
Anew paper published in Science reveals the discovery of a rare planet seemingly far too big for the star it orbits. The findings challenge everything we know about how planets and solar systems form – as well as how scientists model them.
“An object like the one we discovered is likely extremely rare, so detecting it has been really exciting,” said Megan Delamer, an astronomy graduate student at Penn State, USA, and co-author of the paper. “Our current theories of planet formation have trouble accounting for what we’re seeing.”
The newly identified giant planet is 13 times as massive as Earth, with a similar mass to the ice giant Neptune. What’s strange is that the ultracool star it’s orbiting (named LHS 3154) is nine times less massive than our Sun. That makes the mass ratio of the planet to its star more than 100 times that of Earth to the Sun.
The discovery marks the first time that scientists have found such a big planet orbiting such a small star. In fact, ultracool stars are famously the coldest and least massive stars in the Universe.
Existing scientific theories posit that stars form from vast clouds of dust and gas. When that process is finished, the remaining matter in the disc orbiting the star develops into planets. But LHS 3154 doesn’t have enough mass (and not enough matter in its disc) to make a planet as massive as this, according to existing theories – forcing scientists to re-examine their ideas.
In fact, according to the scientists’ calculations, the dust-to-mass a
