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Astronomers have discovered a pair of stars with the shortest orbits ever observed

Astronomers have discovered a pair of stars with such short orbits that they orbit each other in just 51 minutes.  The system is known as cataclysmic variability, when the two stars approach over billions of years causing the white dwarf to start accreting, or eating material from the partner star (as shown above).
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Astronomers have discovered a pair of stars with such short orbits that they orbit each other in just 51 minutes.

The system appears to be one of a rare binary system known as a “cataclysmic variable,” in which a star similar to our sun orbits tightly around the hot, dense core of a white dwarf — a burned-out star.

Cataclysmic variability occurs when two stars approach over billions of years, when the white dwarf starts accreting or eating material from the partner star.

This process can produce huge, variable flashes of light that astronomers thought centuries ago were the result of some unknown cataclysm.

About 3,000 light-years from Earth in the constellation Hercules, the “cataclysmic” system has the shortest orbit of its kind ever discovered.

It was discovered by astronomers at MIT and named ZTF J1813+4251.

Astronomers have discovered a pair of stars with such short orbits that they orbit each other in just 51 minutes.  The system is known as cataclysmic variability, when the two stars approach over billions of years causing the white dwarf to start accreting, or eating material from the partner star (as shown above).

Astronomers have discovered a pair of stars with such short orbits that they orbit each other in just 51 minutes. The system is known as cataclysmic variability, when the two stars approach over billions of years causing the white dwarf to start accreting, or eating material from the partner star (as shown above).

WHAT IS A CATACLYSMIC VARIABLE?

Cataclysmic variability occurs when two stars approach over billions of years, when the white dwarf starts accreting or eating material from the partner star.

This process can produce huge, variable flashes of light that astronomers thought centuries ago were the result of some unknown cataclysm.

It is for this reason that cataclysmic variables are among the most frequently found astronomical objects by amateurs.

This is because the cataclysm variable during the explosion phase is bright enough to be detected by very modest instruments, and the only celestial bodies easily confused with it are the bright asteroids, which move clearly from night to night.

Unlike other such systems observed in the past, the experts captured this cataclysmic variable as the stars repeatedly eclipsed each other, allowing the team to precisely measure the properties of each star.

They then ran simulations of what the system is doing today and how it should evolve over the next hundreds of millions of years.

This has led researchers to theorize that the stars are currently in transition, and that a sun-like star is orbiting and “donating” much of its hydrogen atmosphere to the voracious white dwarf.

Over time, astronomers say, the sun-like star will eventually collapse into a mostly dense, helium-rich core.

In another 70 million years, the stars will move closer together in an ultrashort orbit lasting only 18 minutes before they begin to expand and drift apart.

Decades ago, researchers at MIT and elsewhere predicted such cataclysmic transitions to ultrashort orbits, but this is the first time such a transition system has been observed directly.

“This is a rare event where we catch one of these systems in the act of transitioning from hydrogen to helium accretion,” said Kevin Burdge of MIT’s Department of Physics.

“People predicted that these objects would go into ultrashort orbits, and it was long debated whether they were short enough to emit detectable gravitational waves. This discovery stops that.”

Using a camera attached to a telescope at Palomar Observatory in California, Burdge and colleagues discovered the new system within the vast star catalog observed by the Zwicky Transient Facility (ZTF) to capture high-resolution images of large areas. the sky

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

Burdge combed the catalog for signals from systems with ultrashort orbits, whose dynamics can be so extreme that they should emit dramatic bursts of light and gravitational waves.

These flash repeatedly with a period of less than an hour – a frequency that usually signals at least two closely orbiting systems, one of which crosses the other and briefly blocks their light.

The discovery was made by the Zwicky Transient Facility (ZTF) at Caltech's Palomar Observatory with assistance from the WM Keck Observatory in Hawaii (pictured).

The discovery was made by the Zwicky Transient Facility (ZTF) at Caltech’s Palomar Observatory with assistance from the WM Keck Observatory in Hawaii (pictured).

Burdge used an algorithm to remove more than 1 billion stars, each recorded over 1000 ways and zeroed in on ZTF J1813+4251.

“This thing came up, where I saw an eclipse happening every 51 minutes, and I said, OK, it’s definitely a binary,” Burdge said.

He and his colleagues then focused on a system using the WM Keck Observatory in Hawaii and the Gran Telescopio Canarias in Spain.

They found that the first object was probably a white dwarf about 1/100 the size of the sun and about half the mass.

The second was a sun-like star near the end of its life, one-tenth the size and mass of the sun (about the size of Jupiter).

However, something didn’t quite fit.

“This one star looked like the sun, but the sun can’t fit into an orbit shorter than eight hours – what’s going on here?” Burdge said.

I realized that ZTF J1813+4251 is most likely a cataclysmic variable – a discovery that means it is the shortest-orbiting cataclysmic variable discovered to date.

“It’s a special system,” Burdge said. “We were doubly fortunate to find a system that answers a big open question and is one of the most beautifully behaved cataclysmic variables known.”

This discovery was published in the journal Nature.

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