Originally posted by Wikinews. Wikinews content appears under the Creative Commons Attribution 2.5 license except where specified. As these articles are static snapshots of news items that may be later updated, they may not represent the latest or final revision of that article, and posted information may be only preliminary. Astronomers discover smallest known star ------------------------------------------------------------------------------- July 14, 2017 Original URL: https://en.wikinews.org/wiki/Astronomers_discover_smallest_known_star On Wednesday, astronomers at the University of Cambridge in England announced the discovery of a dwarf star, known as EBLM J0555-57Ab, which is slightly bigger than Saturn and smaller than Jupiter. <!-- USAToday, Sputnik --> It was found using data from an array of automated telescopes called Wide Angle Search for Planets (WASP).<!-- CBC --> The study was published in the journal ''Astronomy & Astrophysics''.<!-- USAToday --> The star belongs to the Milky Way galaxy and it is approximately 600 light years away from Earth. It's mean radius is about 80 percent the size of the largest planet in the Solar System, Jupiter, but despite it's small size it is very dense. Its mass is almost 85±4 times the , the study said.<!-- CBC; the source incorrectly states 49000km as the radius. 49000 is ~80% of Saturn, but the study says it is comparable to that of Saturn and Saturn is ~80% of Jupiter in terms of radius.--> The star's surface gravitational pull is about eleven times stronger than the Sun's -- 300 times the strength by with earth attracts matter. <!-- Sputnik --> It is part of a binary star system. It moves around the galaxy with another star, both orbiting around the same central point. However, it stays so close to its companion star, that it takes about 7.8 days to orbit around the pair's shared centre.<!-- ar Xiv --> The distance between the two stars is less than between Mercury and the Sun, about eight percent of an astronomical unit, in stark contrast to the 100 -- 1000 astronomical units that typically separates two stars in such a system.<!-- CBC --> It was discovered by the method called "astronomical transit".<!--, when it moved in front of its partner star. --> This method is used to discover planets or satellites, and the astronomers initially thought it was merely an exoplanet. During the planet's revolution, when it crosses it's parent star, there is a dip it the brightness of the light coming from the parent star. The companion of this dwarf is of the size of the Sun, and it is brighter than the dwarf making the discovery more difficult.<!-- Sputnik, CBC --> "Indeed, until we measured the mass it looked just like a transiting planet", Amaury Triaud, co-author of the paper, told ''Popular Mechanics''. With a brightness 2000 to 3000 times fainter than the Sun, it was the mass that indicated it was actually a dim star.<!-- CBC --> According to lead author of the study, Alexander von Boetticher, their "discovery reveals how small stars can be." He added, "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".<!-- Sputnik --> A brown dwarf converts hydrogen to Deuterium, a hydrogen isotope, rather than helium, like other stars including the Sun. The tiny star's temperature is lesser than most known gas giant exoplanets.<!-- ac: there is an exoplanet hotter than some stars, and there is a star, cooler than some exoplanets! --> "That star likely represents the smallest natural fusion reactor that we know of[...] We're trying to replicate fusion on Earth in labs, but that's basically as small as it gets in nature", Triaud told CBC News. The size of the star makes it difficult to study, but the brightness of its companion star also makes it more challenging. "It's like trying to look at a candle beside a lighthouse," Triaud said.<!-- CBC --> == Sources == * https://sputniknews.com/science/201707131055492838-astronomers-tiniest-dwarf-star-ever/ * https://arxiv.org/abs/1706.08781 * https://www.usatoday.com/story/tech/science/2017/07/11/smallest-star-universe-has-been-discovered/469773001/ * http://www.cbc.ca/news/technology/smallest-star-discovered-1.4199325 * http://www.popularmechanics.com/space/deep-space/news/a27260/smallest-star-ever-discovered-by-astronomers/