Scientists have discovered the smallest-known star in the universe – slightly larger than Saturn in size – which may possibly have Earth-sized planets with liquid water in its orbit.

EBLM J0555-57Ab has a comparable mass to Trappist-1, the ultracool dwarf star that was found earlier this year to be circled by at least seven Earth-sized planets. The newly-measured star is part of abinary system, and was identified as it passed in front of its muchlarger companion, a method which is usually used to detect planets,not stars.

EBLM J0555-57Ab looks a bit like it shouldn’t have made the cut: It’s only a tiny bit larger than Saturn, or about one-twelfth the size of our sun. In fact, the star is so small that it isn’t putting out much heat. This star is smaller, and likely colder than numerous gas giant exoplanets that have so far been identified, researchers said.

Researchers believe the star is just beyond the threshold separating brown dwarfs from stars.  EBLM J0555-57Ab is around 600 light-years from Earth, and is smaller than Jupiter – yet its mass is 85 times greater than that of the gas giant.

The star was identified by WASP, a planet-finding experiment run by several universities. It’s barely bigger than Saturn and even smaller than Jupiter. That’s just over where scientists think the line between stars and failed stars, also known as brown dwarfs, falls – at about 83 Jupiter-masses for stars with a composition like the new one’s.

“The smallest stars provide optimal conditions for the discoveryof Earth-like planets, and for the remote exploration of theiratmospheres,” said co-author Amaury Triaud, senior researcher atCambridge’s Institute of Astronomy. “However, before we can studyplanets, we absolutely need to understand their star; this is fundamental.”