Astronomers Find A "Cataclysmic" Star Pair That Orbit Each Other Every 51 Minutes

In yet another discovery, astronomers at MIT and elsewhere have found a pair of stars that has the shortest orbital period yet discovered. The star circles each other every 51 minutes.

Astronomers dub these systems as a "cataclysmic variable," in which a star similar to ours orbits tightly around a white dwarf- a hot, dense core of a burned-out star, ANI reported.

The discovery of a new cataclysmic variable has been published in the journal Nature. The newly discovered system, which the team has tagged ZTF J1813+4251, is a cataclysmic variable with the shortest orbit detected to date. Unlike other such systems observed in the past, the astronomers caught this cataclysmic variable as the stars eclipsed each other multiple times, allowing the team to precisely measure the properties of each star.

The researchers ran simulations of what the system is likely doing today and how it should evolve over the next hundreds of millions of years. They conclude that the stars are currently in transition and that the sun-like star has been circling and "donating" much of its hydrogen atmosphere to the voracious white dwarf. The sun-like star will eventually be stripped down to a mostly dense, helium-rich core. In another 70 million years, the stars will migrate even closer together, with an ultrashort orbit reaching just 18 minutes, before they begin to expand and drift apart.

Decades ago, researchers at MIT and elsewhere predicted that such cataclysmic variables should transition to ultrashort orbits. This is the first time such a transitioning system has been observed directly.

"This is a rare case where we caught one of these systems in the act of switching from hydrogen to helium accretion," says Kevin Burdge, a Pappalardo Fellow in MIT's Department of Physics. "People predicted these objects should transition to ultrashort orbits, and it was debated for a long time whether they could get short enough to emit detectable gravitational waves. This discovery puts that to rest."

The astronomers discovered the new system within a vast catalogue of stars, observed by the Zwicky Transient Facility (ZTF), a survey that uses a camera attached to a telescope at the Palomar Observatory in California to take high-resolution pictures of wide swaths of the sky.

The survey has taken more than 1,000 images of each of the more than 1 billion stars in the sky, recording each star's changing brightness over days, months, and years.