Fastest nova ever recorded by astronomers

Fastest nova ever recorded by astronomers

Fastest nova ever recorded by astronomers

Fastest nova ever recorded by astronomers

An illustration of an intermediate polar system, a type of two-star system to which the research team believes V1674 Hercules belongs. Image Credit: Mark Garlick

A nova is a bright explosion in a binary star system in which a white dwarf steals material from its companion. The material is heated to a point where it ignites and is flung out at high speed, making the star a lot brighter than before. Unlike a supernova, white dwarfs can survive a nova event and do it again. Now astronomers have seen the fastest nova ever.

Most novas tend to brighten and then fade over the course of a few weeks, but as reported in the American Astronomical Society’s Research Notes, V1674 Hercules is not your usual nova. It faded in just a day and that was just the beginning of its madness.

“It was only about one day, and the previous fastest nova was one we studied in 1991, V838 Herculis, which declined in about two or three days,” project leader Professor Sumner Starrfield, an astrophysicist in ASU’s School of Earth and Space Exploration , said in a statement.

The star acts a bit like a ringing bell. There is a wobble every 501 seconds, and astronomers were able to observe it in both visible light and X-rays. On June 12, 2021, it was so bright that it could be seen with the naked eye. Even a year after the nova was first observed, the wobble continues to repeat itself.

They believe that the two stars and the material they exchange align with an “intermediate polar system.” In those binary interactions, the The gas flow from the large companion stellar companion first hits the accretion disk that surrounds the white dwarf (the dense remaining core of a star that has burned up all of its hydrogen) and then moves toward the dwarf along the magnetic field lines.

“Most unusually, this oscillation was seen before the eruption, but it was also evident when the nova was about 10 magnitudes brighter,” added study co-author Dr. Mark Wagner, chief of science at the Large Binocular Telescope Observatory used to observe the nova.

“One mystery that people struggle with is what causes this periodicity that you would see it across that brightness range in the system.”

The object was first discovered by an amateur astronomer from Japan, Seidji Ueda, who put it on the scientists’ radar. Understanding these stellar explosions, even in extremely rare cases like this one, isn’t just about expanding our knowledge of stars. It can also tell us how these events contributed to the chemical makeup of the solar system.

“We’re always trying to figure out how the solar system came to be, where the chemical elements in the solar system come from,” Starrfield says.

“One of the things we’re going to learn from this nova, for example, is how much lithium was produced by this explosion. We are now pretty sure that a significant amount of the lithium we have on Earth has been produced by these types of explosions.”

The system also somehow shapes the flow of the ejecta, suggesting there’s even more about V1674 Hercules’ idiosyncratic system that astronomers need to investigate.

While a nova is not a supernova, it is considered a precursor. With each nova, some of the matter remains on the white dwarf until it becomes too much and collapses on its own, creating a Type Ia supernova.