Researchers Watch as the Largest Known Star Tears Itself Apart

The largest known star in the universe is tearing itself apart, according to an international team of researchers who say observations of the process offer a new look into how massive stars release material into interstellar space.

Stars boasting masses many times larger than the Sun burn brightly and quickly away, with lives much shorter than their less dramatic peers. Toward the end, they become unstable, ejecting material enriched by nuclear reactions that take place deep within the star. This material includes many of the necessary ingredients not only for the creation of rocky planets, but life. What is unclear, however, is how it is ejected and how the process affects the star's evolution.

An international team of researchers using the European Southern Observatory's (ESO) Very Large Telescope (VLT) has detected a huge cloud of glowing hydrogen gas around a star known as W26 in the galaxy's most massive cluster of stars, Westerlund 1. The discovery marks the first time an ionized nebula was ever discovered around a red supergiant like W26, which, with a radius 1,500 times larger than the Sun, is likely the largest star ever discovered.

Because W26 is not hot enough to cause the gas to glow, researchers speculate that either hot blue stars located elsewhere in the in the cluster or a hotter but fainter companion star are to blame. However, W26's size and brightness both suggest the star is nearing its end, and will shortly erupt in the form of a supernova.

In many ways, W26's nebula resembles one found around a star remnant that exploded in 1987, resulting in the closest observed supernova to Earth since 1604. Studying objects like these, the researchers explain, will unlock the answers to questions regarding the process through which these massive stars slough off their material, and how the process eventually triggers their fiery end.