A team of astronomers at the University of Cambridge have just discovered the smallest star ever measured. The tiny twinkle is only slightly larger than Saturn, but has a gravitational strength about 300 times greater than that of Earth.
The star is considered to be among the smallest possible star sizes, as the mass is only barely over the threshold to allow for hydrogen nuclei to fuse into helium, an essential reaction required to keep a star going.
If the star were any smaller, the pressure at the star’s center would inhibit such reactions from occurring. Furthermore, the star would transform into a brown dwarf at smaller sizes.
The same reactions are what power our own star, the sun. Scientists have been trying to reproduce hydrogen fusion on Earth.
Small stars, such as what was discovered, are considered to be the most likely to have Earth-sized planets with liquid water on their surfaces orbiting them, according to the University of Cambridge. One example is TRAPPIST-1, an ultracool dwarf star with seven Earth-sized, temperate planets.
The newly-discovered star has been labeled EBLM J0555-57Ab and is approximately 600 light-years from us. The star was found by WASP, the Wide Angle Search for Planets, an experiment for finding planets conducted by the Universities of Keele, Warwick, Leicester and St. Andrews. When EBLM J0555-57Ab crossed its parent star, the parent star became dimmer, allowing scientists to determine its existence as part of a binary system. This means there are only the two stars in orbit.
The mass of the new star was found using the CORALIE spectrograph, a device which separates light into different frequencies (think of different colors). The star is considered to be possibly colder than many gas giant exoplanets discovered thus far.
According to Alexander von Boetticher, author of the study, and master’s student at Cambridge’s Cavendish Laboratory and Institute of Astronomy, in cases of stars as small as EBLM J0555-57Ab, the chances of finding them are slimmer than finding planets on certain occasions. The new star has a similar mass to that of TRAPPIST-1, but with a radius almost 30 percent lower.
The smallest stars have the best conditions for remote exploration of their atmospheres, according to Amaury Triaud, senior researcher at Cambridge’s Institute of Astronomy. Despite their high abundance in our cosmos, these tiny nuclear bombs with sizes and masses under 20 percent that of the sun are not well understood by scientists.