ESO astronomers have discovered a pair of enormous stars, known as an overcontact binary system, that orbit so close to each other that a bridge of stellar material has formed. Scientists predict that at some point, the strange partnership will end in spectacular fashion, with the stellar bodies either merging to create a single titanic star, or in a violent supernova, that would birth a binary black hole system.
Situated in the Tarantula Nebula around 160,000 light-years distant from Earth, VFTS 352 is unusual for a number of reasons. For one, the O-type stars that form the system are the most massive ever discovered, boasting a combined mass the equivalent of 57 Suns, and a surface temperature of around 40,000 ºC (72,032 ºF), making it the hottest overcontact binary system ever discovered. But most intriguingly, the stars are almost identical in size.
It has been observed in the past that when O-type stars orbit close enough for a bridge to form, that one of the bodies is significantly larger than the other, resulting in the smaller body siphoning material off of its companion, essentially becoming a "vampire star." But in the case of VFTS 352, the mass of both O-trype stars is incredibly similar, meaning that they share around 30 percent of their mass in a roughly even manner, so far as we can tell from telescopic observations.
Based on previous observations of similar binary systems, this stage in the life of the stellar twins is likely to be short-lived, at least in cosmic terms. In time, the close proximity of the stars may result in them merging to form a single enormous stellar body. In this scenario, the vast, rapidly spinning star would most probably end its life in an energetic explosion known as a long-duration gamma-ray burst.
The second possibility, predicated on a mixing of material between the two stars interiors via powerful tidal forces, would see the stellar bodies explode in twin supernovae, creating a binary system of black holes – an evolutionary path that would exist outside of standard stellar evolution predictions.
A paper on the findings has been published online in the Astrophysical Journal.
Scroll down to see an animation of the binary system VFTS 352.