A team of astronomers led by the University of Cambridge appear to have discovered the smallest known star yet. Named EBLM J0555-57Ab, this star is located about six hundred light years away from the Earth. EBLM J0555-57Ab is slightly bigger than Saturn and has a gravitational pull at its stellar surface that is about 300 times stronger than the Earth. Alexander Boetticher, is the lead author of this study, and a Master’s student at Cambridge’s Cavendish Laboratory and Institute of Astronomy.
Scientists believe that this is about the smallest star that can exist in the Universe. This is because a body that is smaller than EBLM J0555-57Ab, will not have sufficient pressure at its centre to enable the fusion of hydrogen nuclei into helium. This process of hydrogen fusion is what powers a star and our very own Sun is no different.
Referring to the study and its findings, Alexander Boetticher said “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.”. When compared with TRAPPIST-1, this newly discovered star has a similar mass but the radius is nearly 30% smaller. “
Image Source: Astronomy.com
“This star is smaller, and likely colder than many of the gas giant exoplanets that have so far been identified,” added Boetticher. “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.”
It is important to note here why this discovery has special significance to Scientists and Astronomy Lovers. Stars with mass less that 20% of the Sun are, in general, difficult to detect. This is not only due to their small size but also because they are not very bright.
Although they are the most numerous stars in the Universe, stars with sizes and masses less than 20% that of the Sun are poorly understood, since they are difficult to detect due to their small size and low brightness. The EBLM project is an important step in addressing this area.
The smallest stars provide optimal conditions for the discovery of Earth-like planets, and for the remote exploration of their atmospheres,” added co-author Amaury Triaud, senior researcher at Cambridge’s Institute of Astronomy.
“However, before we can study planets, we absolutely need to understand their star; this is fundamental.”
Article Source and Image credit: Astrowatch