Massive Crash in Space Reveals the Answer
Jets and Debris from a Neutron Star Collision. Credit: NASA’s Goddard Space Flight Center/CI Lab. This animation captures phenomena observed over the course of nine days following the neutron star merger known as GW170817. They include gravitational waves (pale arcs); a near-light-speed jet that produced gamma rays (magenta); expanding debris from a “kilonova” that produced ultraviolet (violet), optical, and infrared (blue-white to red) emissions; and, once the jet directed toward us expanded into our view from Earth, X-rays (blue).
The crash was so tremendous that it was seen – and heard – from our little outpost about 100 million years away (which is actually incredibly close) across space and time.
Stellar collisions are typically between black holes, and produce gravitational waves (detected for the first time in just the past two years). But this “kilanova” collision, observed in the constellation Hydra on August 17 and announced by a global scientific team on October 16, was between two neutron stars, and was massive enough that, as The New York Times reports, it “set off sensors in space and on Earth, as well as producing a loud chirp in antennas designed to study ripples in the cosmic fabric. It sent astronomers stampeding to their telescopes, in hopes of answering one of the long-sought mysteries of the universe.” Some of those stampeding astronomers were at the Weizmann Institute of Science, including Profs. Avishay Gal-Yam and Eran Ofek. Their findings are adding to the knowledge gained from this collision.
And unlike crashes between black holes, the neutron star merger put out massive amounts of new types of data. As Prof. Gal-Yam says, “When black holes collide, the only thing we can detect is gravitational waves; everything else is swallowed inside.” But with this crash, scientists got more than gravitational waves: because neutron stars are lighter than black holes, some of their mass and radiation exited with the waves. Equipment detected X, gamma, and infrared rays; visible light; and – for the first time – heavy elements such as tellurium, cesium, and iodine. In fact, Prof. Gal-Yam says that “Our findings suggest, among other things, that every atom of iodine on Earth, including the iodine you put on your wound, had arrived here in the distant past from a merger of neutron stars.”
Thanks to a powerful initiative – and its powerful equipment – known as LIGO (Laser Inferometer Gravitational-Wave Observatory) that is housed at Caltech, where its inventors just won the 2017 Nobel Prize in Physics, a globe-circling network of astrophysicists is able to continually watch deep space, scanning for new events and processing the massive amounts of data that emerge.
The information from the neutron star collision is sure to keep many dozens of LIGO-affiliated teams – including those at Weizmann – busy for years, as it has shed unprecedented light on space … and Earth.
For example, scientists have long known where light elements come from, and while they theorized that heavy elements were produced by neutron star mergers, were never able to prove it – until now. Some of our most prized precious metals, such as gold, silver, and uranium, are also likely produced by neutron star collisions.
Whether it’s the lighter elements, such as calcium, that make up life on Earth – including us – or the heavier elements that create our nuclear bombs and wedding bands, the stars are part of us, for better or for worse.