Smallest Known Star Discovered

This week astronomers at University of Cambridge announced discovery of EBLM JO555-57Ab, the smallest star ever identified by science. To ponder EBLM JO555-57Ab, cast an eye of imagination 600 light years across the cosmos. Recline in upholstered comfort, search for unmistakable washes of sunlight emanating from a cosmic body smaller than Jupiter, barely larger than Saturn. Marvel at the fickle nature of our universe while dismissing notions of mandatory solar enormity. Despite a meager footprint, know that a star, is a star, is a star.

Demure as EBLM JO555-57Ab appears, mass not size determines star status. More mass = more gravity, exceptional gravity smashes particles together creating nuclear fusion which releases energy as light, radiation and solar wind. See How Stars Work at –

Alexander Boetticher, lead study author doubts stars get much smaller than EBLM JO555-57Ab.

“Our discovery reveals how small stars can be. Had this star formed with only a slightly lower mass, the fusion reaction of hydrogen in its core could not be sustained, and the star would instead have transformed into a brown dwarf.”

EBLM JO555-57Ab resides in a double star system, but for this critical detail, astronomers might never have noticed EBLM JO555-57Ab passing in front of her larger companion star. Curiously, dim, coolish, barely a star like our now know smallest star, are the “best candidates” for finding Earth sized exoplanets with surface water. Boetticher adds –

[EBLM J0555-57Ab] is smaller, and likely colder, than many of the gas giant exoplanets that have so far been identified. 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. Thankfully, we can find these small stars with planet-hunting equipment, when they orbit a larger host star in a binary system.

It might sound incredible, but finding a star can at times be harder than finding a planet.

Artist’s concept of newly-measured smallest star, called EBLM J0555-57Ab, in contrast to planets Jupiter and Saturn and to the small, cool star Trappist-1, known to be home to at least 7 planets. Image via University of Cambridge.