Smallest-ever star is only slightly larger than Saturn


Defying what astronomers believed until now, a new star – the smallest ever discovered till date – has been found. The star called EBLM J0555-57Ab is so small that is is just slightly larger than Saturn in size.

Located about six hundred light years away, the star was discovered by astronomers at University of Cambridge in the UK when it passed in front of its much larger companion. EBLM J0555-57Ab was detected when it passed in front of, or transited, its larger parent star, forming what is called an eclipsing stellar binary system.

The parent star became dimmer in a periodic fashion, the signature of an orbiting object. Researchers measured the mass of the star was established via the Doppler, wobble method, using data from the CORALIE spectrograph.

With a size just a sliver larger than that of Saturn, the gravitational pull at its stellar surface is about 300 times stronger than what humans feel on Earth. The discovery is also the best possible candidates for detecting Earth-sized planets which can have liquid water on their surfaces, such as TRAPPIST-1, an ultracool dwarf surrounded by seven temperate Earth-sized worlds, researchers said.

The team behind the discovery says that the star is likely as small as stars can possibly become. If it were any smaller, the pressure at the centre of the star would no longer be sufficient to enable this process to take place, they said.

The star was identified by WASP, a planet-finding experiment run by several universities.

This star is smaller, and likely colder than many of the gas giant exoplanets that have so far been identified, researchers said.

While a fascinating feature of stellar physics, it is often harder to measure the size of such dim low-mass stars than for many of the larger planets, they said.

The star has a mass comparable to the current estimate for TRAPPIST-1, but has a radius that is nearly 30 per cent smaller.

“The smallest stars provide optimal conditions for the discovery of Earth-like planets, and for the remote exploration of their atmospheres,” said Amaury Triaud, senior researcher at University of Cambridge


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