Dying stars build humongous 'cocoons' that shake the fabric of space-time

According to recent calculations, dying stars emit massive "cocoons" of gas that might rumble with gravitational waves.

Astronomers frequently listen for the ringing of black holes around the cosmos ever since the first direct observation of the gravitational waves, also known as gravitational waves, was published in 2016. Nearly 100 collisions between black holes (and occasionally neutron stars) have been discovered by initiatives like the Laser Interferometer Gravitational-Wave Observatory (better known as LIGO), which shook the cosmos and sent waves through space.

But according to recent studies, dying stars' jets of roiling gas may soon cause cocoons of rumbling gas to form in space, which LIGO may soon detect. According to research presented this week at the 242nd meeting of the American Astronomical Society, researchers at Northwestern University utilized cutting-edge computer models of huge stars to demonstrate how these cocoons may emit gravitational waves that are "impossible to ignore". Real-world research on these reverberations may shed light on how violently massive stars die.

Massive stars that run out of fuel fall into black holes while simultaneously ejecting enormous jets of extremely fast-moving particles. The researchers reproduced these latter phases of a star's life in the hopes that the jets may result in gravitational waves, but another phenomenon seized the lead.

Ore Gottlieb, the study's principal investigator and an astronomer at Northwestern University's Center for Interdisciplinary Exploration and Research in Astrophysics, said in a statement that when he estimated the gravitational waves from the black hole's proximity, he discovered another source that was interfering with his calculations: the cocoon. The falling star's outer layers combine with the powerful jets emitted from within to create the chaotic gas glob known as the cocoon. Something large and asymmetrically moving is required to generate gravitational waves, much like the turbulent material inside the cocoon.

In order to escape, a jet must first dig its way out from the center of a star, according to Gottlieb. "Imagine drilling a hole through a wall. Debris leaks out of the wall when the rotating drill bit strikes it. That substance receives energy from the drill bit. Similar to that, when the jet pierces the star, stellar material heats up and spills out. This debris creates a cocoon's warm layers.

The ripples the cocoon produced should be simple for LIGO to pick up on during its subsequent series of measurements, according to Gottlieb's estimates. Additionally, because cocoons produce light, astronomers may learn more about them simultaneously using gravitational waves and telescopes, a thrilling achievement known as multi-messenger astronomy.

It will be a fascinating new peek into the interiors of stars and the end of their lives if LIGO does observe a cocoon in the near future. Additionally, it may be the first time that LIGO has been able to identify gravitational waves coming from a single object rather than from the collisions of two binary objects circling one another.

Gottlieb predicted that one day LIGO will discover the first non-binary source of gravitational waves. "As of now, LIGO has only detected gravitational waves from binary systems," he added. One of the first areas we should seek for this kind of supply is cocoons.

A peer-reviewed publication has not yet published the team's study.