An incredible stellar system has been found where two stars are so close that their surfaces are overlapping. It is the hottest and most massive double star system ever seen, and provides a rare glimpse into what is believed to be a relatively brief cosmic event.
The system is known as VFTS 352, found 160,000 light-years away in the Tarantula Nebula by the European South Observatory's Very Large Telescope. Both of the stars are nearly identical in size, with a combined mass 57 times greater than the Sun, meaning one is not sucking material from the other – rather, they are likely sharing 30% of their material. This has led to a “bridge” forming between their two connected surfaces.
The two stars, classed as O-type stars that shine blue-white, have surface temperatures of more than 40,000 degrees Celsius (72,000 degrees Fahrenheit), and complete an orbit of each other in just one Earth day. Double systems like this may be the main source of certain elements such as oxygen in the universe.
Their centers are separated by a mere 12 million kilometers (7.5 million miles), and the intense tidal forces (the gravitational pull of one star on the other) are thought to be mixing the material in their interiors. “The VFTS 352 is the best case yet found for a hot and massive double star that may show this kind of internal mixing,” said lead author Leonardo Almeida from the University of São Paulo, Brazil in a statement. “As such it’s a fascinating and important discovery.”
What will happen next to the stars is especially interesting. It’s possible that the two may combine into a single giant star in 600,000 years that would spin extremely rapidly, and ultimately end in a huge explosion up to four million years later known as a long-duration gamma-ray burst, one of the most explosive events in the universe.
The other possibility is that the two will go supernova separately in about three million years, both becoming black holes but continuing to orbit one another, forming a binary black hole system. “Such a remarkable object would be an intense source of gravitational waves,” Selma de Mink of the University of Amsterdam, the lead theoretical astrophysicist on the team, said in the statement.
Whatever happens, this system is proving to be a fascinating insight into a rare and ethereal phenomenon.