Based on the rate of material spiraling from one star to another in a nearby stellar binary system, astronomers now predict that the two stars will merge sometime between 2067 and 2099, producing a nova that will among the brightest stars in the sky, visible to the naked eye for about a month.

From the press release:

Currently, the faint star V Sagittae, V Sge, in the constellation Sagitta, is barely visible, even in mid-sized telescopes. However, around the year 2083, this innocent star will explode, becoming as bright as Sirius, the brightest star visible in the night sky. During this time of eruption, V Sge will be the most luminous star in the Milky Way galaxy. … “We now have a strong prediction for the future of V Sge,” said Professor Emeritus Bradley E. Schaefer, LSU Department of Physics & Astronomy. “Over the next few decades, the star will brighten rapidly. Around the year 2083, its accretion rate will rise catastrophically, spilling mass at incredibly high rates onto the white dwarf, with this material blazing away. In the final days of this death-spiral, all of the mass from the companion star will fall onto the white dwarf, creating a supermassive wind from the merging star, appearing as bright as Sirius, possibly even as bright as Venus.”

“V Sge is exponentially gaining luminosity with a doubling time scale of 89 years,” said Frank. “This brightening can only result with the rate of mass falling off the normal companion star increasing exponentially, ultimately because the binary orbit is in-spiraling rapidly.”

“In anticipation of this fast decaying of the orbit, the fate of V Sge is sealed,” stated Schaefer. “The critical and simple physics are derived from V Sge having the companion star being much more massive than the white dwarf star, so forcing the rate of mass transfer to rise exponentially. Anticipating the next few decades, V Sge will in-spiral at a rapid pace with increasing brightness. Inevitably, this in-spiral will climax with the majority of the gas in the normal star falling onto the white dwarf, all within the final weeks and days. This falling mass will release a tremendous amount of gravitational potential energy, driving a stellar wind as never before seen, and raise the system luminosity to just short of that of supernovae at peak.”

This explosive event will have peak brightness over a month, with two stars merging into one star. The end result of the merger will produce a single star with a degenerate white dwarf core, a hydrogen-burning layer, surrounded by a vast gas envelope mostly of hydrogen.

The press release has not yet been posted, but the press materials for the announcement can be found here.

If their hypothesis turns out to be true, it will be the first such event ever predicted.

Note that they are not predicting a supernova, an event caused by a variety of ways (all related to the death of a star). This is a less spectacular nova event, though because of its relative nearness will be very bright in our sky.