NASA astronomers using the Far Ultraviolet Spectroscopic Explorer (FUSE) satellite and ground-based telescopes, have discovered the properties of a rare, extremely massive, and young binary star system at sizes dwarfing the Sun, NASA announced May 28.

Known as LH54-425, the system is located in the Large Magellanic Cloud, a satellite galaxy of the Milky Way. The two O-stars – the most massive and luminous types of stars in the universe – weigh in at approximately 62 and 37 times the mass of the Sun. The spectra was obtained by Georgia State University astronomer Stephen Williams using a 1.5-meter (4.9 foot) telescope at the an observatory in Chile.

"The stars are so close to each other — about one-sixth the average Earth-Sun distance — that they orbit around a common center of mass every 2.25 days," said Williams’ Georgia State colleague, Douglas Gies, in Atlanta.

With its combined mass of nearly 100 suns, the system is one the most extreme binaries known. The stars are believed to be less than 3 million years old, in comparison to the approximately 4.5 billion-year-old Sun.

Each star blows off a powerful stellar wind, and FUSE’s observations have provided details of when the two supersonic winds collide: The wind collision zone wraps around the smaller star and produces a curved surface of superheated gases that emit X-rays and far-ultraviolet radiation. FUSE is ideal for these measurements because the lines that best indicate the properties of stellar winds show up in the far ultraviolet part of the spectrum, where FUSE is most sensitive.

Against wind speed estimated at 5.4 million miles per hour, the more massive star sheds material at a rate of 500 trillion tons per second, about 400 times greater than what the Sun loses through the solar wind. The smaller star loses mass at about one-tenth that rate. NASA described the mass-loss rate of both stars as consistent with other single stars having the same temperature and luminosity.

Scientists said as the stars age and expand, they will transfer substantial mass to each other throughout a process that may begin in a million years. Being so close together, they are likely to merge as they evolve, producing a single extremely massive star like the more massive member of the Eta Carinae binary system, one of the most massive and luminous stars in the Milky Way, with perhaps 100 solar masses. Ultimately they will produce "a very energetic" supernova, according to NASA.

"These stars are evolving in the blink of an eye compared to the sun, which has looked pretty much the same for over 4 billion years," adds Rosina Iping of the Catholic University in Washington, D.C., and NASA’s Goddard Space Flight Center, which manages the FUSE program.