Proven: Gold, platinum are created by collisions of dead stars!
In a major development in astronomy, scientists have detected the warping of space caused by collision of dead stars. This has proven a long-suspected theory: that gold and heavy metals are created by such explosions. The outburst in question took place 130mn years ago in the 'NGC 4993' galaxy. It is 1,000 billion kilometers away: so far that light has only just reached earth!
The collision that was detected involved dead stars, or 'neutron stars', in Constellation Hydra that had masses 10-20% greater than the Sun. Even those were the leftovers of more massive stars which exploded earlier as supernovas. Such powerful explosions cause electrons and protons in the star to combine to form only neutrons. The remnants are extremely dense: a teaspoonful can weigh a billion tonnes.
Gravitational waves, ripples through space-time produced by violent phenomena in the cosmos, were predicted by Albert Einstein in 1916 in his Theory of General Relativity. They pass over earth all the time, but we only recently got advanced instruments to detect them.
Such collisions send out gravitational waves that stretch and squeeze everything they pass through by a minuscule amount: less than an atom. Effects of the explosion were detected by the LIGO-VIRGO Collaboration lab at Livingston in Louisiana, which has two 4km pipelines crossing each other at right angles. Each pipe has a powerful laser that accurately measures the tiniest of changes in their length.
The LIGO detector, which was designed to catch gravitational ripples, was upgraded two years ago. It has since sensed collision of black holes four times. On August 17, for the first time, it detected gravitational waves (and light, and gold) from the collision of neutron stars- a kilonova. That helped telescopes all over the world to capture the first pictures of such an event.
Researchers had suspected the resultant release of energy created rare elements. "We have discovered that this neutron star merger scattered heavy elements, like gold and platinum, out into space at high speeds," said Dr Kate Maguire of Queen's University Belfast. "They tell us that heavy elements are cinders, forged in the billion-degree remnants of merging neutron stars," said Dr Joe Lyman of Warwick University.
Gravitational waves were first directly detected only in 2014, then from the collision of black holes. But no light emanated, so they were invisible and could only be heard, plus they lasted for fraction of a second. The latest discovery of gravitational waves (as well as light) from collision of neutron stars, which lasted 100 seconds, has opened new doors for scientists.
During this discovery, researchers could also measure the rate of expansion of the universe with a technique that was proposed in 1986. Stephen Hawking said it was "the first rung of a ladder" for the new method. The LIGO's sensitivity is now being increased to double within a year. Researchers hope this paves the way for detecting newer celestial objects that are currently unimaginable.
