A small star blew up a bigger star's funeral by exploding — but still missing the bullseye

• A star’s ‘death process’ was interrupted by its neighbouring star, according to a new study in Astronomy and Astrophysics.
• Instead of exploding into a supernova or turning into a white dwarf, the star’s outer layers now lie scattered and its core is exposed.
• Understanding how this happened can help scientists understand how Sun-like stars die and what the future may hold for our own solar system.

Stars have much longer life spans than humans. Our Sun, for instance, is 4.6 billion years old with another 4.5-5.5 billion years to go, before it dies. However, stars still change with age and eventually die.

The bigger star of the system HD101584 was doing just that when another star got in the way. Instead of turning into a white dwarf or exploding like a supernova — the star’s outer layers now lie scattered and its core’s been left exposed.

"The star system HD101584 is special in the sense that this ‘death process’ was terminated prematurely and dramatically as a nearby low-mass companion star was engulfed by the giant," said Hans Olofsson of the Chalmers University of Technology and the lead author of the study published in Astronomy & Astrophysics.

Death at a funeral
As a star gets older, it swells up into a large and bright red giant. Over time, it’s outer layers would shed, leaving behind just the core — a transformation that turns it into a white dwarf.

According to the observations collected by ALMA and APEX, the scientists were able to determine that the event was akin to what is called ‘stellar flight’.

As this star swelled up, its nearby smaller star got pulled in. Although it didn’t collide with the core to create a supernova, which is what normally happens, the move still triggered an outburst.

The deadly blow tore through the star’s gaseous layers, blasted through the previously ejected material to form rings of gas and, bluish and reddish blobs in the nebula.

Although the star’s death was premature and far from the way that scientists normally perceive the end of a star’s life — researchers hope that the new information will help them better understand the final evolution of stars like the Sun.

The two-star game
Binary stars are in vogue with the scientific community. The Zwicky Transient Facility (ZTF), for instance, is studying two white dwarf stars 8,000 light-years away from Earth. The pair is noted for being one of the few known sources of gravitational waves in the universe, which is causing them to inch closer and merge.

Another pair of stars are dragging the fabric of space and time along with them. According to Albert Einstein, that’s exactly what happens when the principle of general relativity is at play and the ‘frame-dragging’ effect occurs.

Binary systems are key to understanding how the universe functions and what the future holds with respect to Earth and its Sun.

"Currently, we can describe the death processes common to many Sun-like stars, but we cannot explain why or exactly how they happen. HD101584 gives us important clues to solve this puzzle since it is currently in a short transitional phase between better studied evolutionary stages," said the study’s co-author Sofia Ramstedt from the Uppsala University.

See also:
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Two dead stars are causing an eclipse every seven minutes

NASA's planet-hunter uncovers its first world with two stars 1,300 light-years away