A supernova exploded near Earth about 2.5 million years ago, possibly causing an extinction event.
- Researchers from the University of Munich find evidence of a supernova near Earth.
- A star exploded close to our planet about 2.5 million years ago.
- The scientists deduced this by finding unusual concentrations of isotopes, created by a supernova.
If you wanted some more shattering news, we now know that a supernova exploded very close to Earth about 2.5 million years ago. That might sound like a long time ago, but in the life of our 4.5 billion-year-old planet, that's just yesterday.
Supernovas are amazingly bright explosions of stars at the end of their lives. A recent study found a blast 4.5 million light-years away could release as much as 10 times the amount of energy that a sun can emit in its lifetime. It also spreads a tremendous amount of chemicals all throughout the cosmos. Just-released research looked at such a spread and found that concentrations of particular elements point to a supernova near Earth just 2.5 million years ago.
The scientists found an unusual amount of 53Mn, a radioisotope made by supernovas. Previous studies looked for such traces in concentrations of 60Fe, an isotope of iron.
The scientists, led by Dr. Gunther Korschinek from the Technical University of Munich, focused their study on ferromanganese crusts. These marine sediments, composed mainly of iron and manganese oxides, grow in time and jut out from the water. This makes them great record-keepers of chemicals in the water around them. While examining these ferromanganese crusts from locations in the Pacific Ocean, the team found not only the isotope 60Fe, but also 53Mn. The samples came from 1,589 meters (5,213 feet) down to 5,120 meters (3.18 miles) down.
What does the presence of 60Fe tell the researchers? It's half-life of 2.6 million years indicates that it was created in a nearby supernova explosion in relatively recently times. Otherwise, 60Fe would have decayed into nickel.
One other explanation for the presence of the isotope is its possible creation in the death throes of asymptotic giant branch (AGB) stars. But the presence of 53Mn, which cannot be produced by such stars, clearly points to supernovae as the origin, think the scientists.
This Manganese crust started to form about 20 million years ago. Growing layer by layer, it resulted in minerals precipitated out of seawater.
Elevated concentrations of 60 Fe and 56 Mn in layers from 2.5 million years ago hints at a nearby supernova explosion around that time. Credit: Dominik Koll/ TUM
"The increased concentrations of manganese-53 can be taken as the 'smoking gun' – the ultimate proof that this supernova really did take place," shared Dr. Korschinek in a press release.
The researchers used accelerator mass spectrometry to locate the 53Mn atoms in the crust that looks like hardened chocolate cake.
"This is investigative ultra-trace analysis," said Korschinek. "We are talking about merely a few atoms here." He explained further that the technique is also very useful in figuring out the sizes of the original stars, adding "accelerator mass spectrometry is so sensitive that it even allows us to calculate from our measurements that the star that exploded must have had around 11 to 25 times the size of the sun."
If there was a supernova in Earth's relatively recent history, what effect did it have on the planet? The scientists think it likely caused cosmic ray showers and affected the climate. It might have also caused a partial extinction event – the Pliocene marine megafauna extinction
Check out the study "Supernova-Produced 53Mn on Earth" in the journal Physical Review Letters.
This discovery finally points to the source of Earth's precious heavy elements, also proves Einstein correct in more ways than one.
Last September, scientists at a special observatory announced that they detected a gravitational wave for the first time. The detection took place in September, 2015, but wasn’t announced until last year. The observatory is known as the Laser Interferometer Gravitational-Wave Observatory (LIGO). It registered ripples in space-time formed from the collision of two black holes. Apparently, the fabric of the universe ripples just as water does.
We’ve tired the electromagnetic spectrum when it comes to examining the universe. Now, astronomers are fiddling with a whole new aperture, gravitational waves. A little over 100 years ago, Einstein first predicted gravitational waves as something that would happen throughout space-time as a result of dramatic events. September’s announcement proved him right, although he himself thought we’d never be able to detect them, the results being so slight.
Officials at the National Science Foundation, LIGO, MIT, Caltech, and other institutions have now made a second groundbreaking announcement, the detection of gravitational waves from another astronomical event, the merging of two neutron stars. This latest signal was detected on Aug. 17. A neutron star is the remnant of a larger star whose core has collapsed. Usually, this is followed by a supernova, where the outer layer of the star blows off in a colossal explosion.
The neutron stars that merged were each 1.1 to 1.4 times the mass of our sun. An event of this magnitude only occurs once in 80,000 years, LIGO scientists say. The light emitted by this neutron star collision resulted in a “fireball,” which is an intense burst of gamma radiation. Such a fireball or kilonova creates the heaviest known elements, such as gold, platinum, and lead, and sends them careening throughout the cosmos.
See an animated clip of a neutron star collision here:
These are small, dense stars. One teaspoon worth would weigh more than 10 million tons, more than the entire population of Earth. As the core continues to collapse, the gravity inside gets so strong it fuses protons and electrons together, forming neutrons, hence the name. When two neutron stars merge, one of two things happen. Either an even bigger neutron star is born or a black hole is made. This event, now known as GW170817, created an ultra-dense neutron star.
Though it occurred approximately 130 million years ago, the resulting gravitational waves reached Earth last August, with the ripples arriving one second before the light did. This is the very first time scientists recorded an astronomical event through both light and gravitational waves.
Over 1,200 scientists from 100 institutions around the world work at the LIGO Scientific Collaboration. LIGO is comprised of two observatories, one in Hanford, Washington, and the other in Livingston, Louisiana. Each contains an instrument so sensitive it can detect a single ripple in space-time lasting just a fraction of a second. In addition to the LIGO detectors, the newly launched Virgo observatory in Italy helped to zero-in on the location of the explosion. Other such observatories are in the works for Japan and India, which will further help pinpoint an event’s location.
Each observatory consists of an L-shaped tunnel. Laser light is sent by mirror down each of them. When there are no gravitational fluctuations, the laser bounces back normally. But when there are ripples in space-time, it squeezes and pulls the beam which gives scientists a reading.
Artist concept of neutron star falling into its neighbor. Credit: NASA
Caltech’s David H. Reitze is the executive director of the LIGO Laboratory. In a press release, he explained the importance of the groundbreaking even. “This detection opens the window of a long-awaited ‘multi-messenger’ astronomy. It’s the first time that we’ve observed a cataclysmic astrophysical event in both gravitational waves and electromagnetic waves — our cosmic messengers,” Dr. Reitze said, “Gravitational-wave astronomy offers new opportunities to understand the properties of neutron stars in ways that just can’t be achieved with electromagnetic astronomy alone.”
The event also solidified another of Einstein’s predictions. Not only does it further confirm the existence of gravitational waves but that they travel at the speed of light. Its little wonder that the scientists who put together LIGO won this year’s Nobel Prize in Physics.
See the announcement of this historic event in astronomy here: