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Study Suggests A Supernova Exploded Near Earth About 2.5 Million Years Ago, Possibly Causing An Extinction Event

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Supernovas are amazingly bright explosions of massive stars at the end of their lives. During the gravitational collapse, the outer layers of the star are pushed away, and chemical elements formed inside the dying star are released into space. This cosmic dust rains down onto the Earth continuously, eventually becoming part of sediments deposited in the sea.

Research published in the journal Physical Review Letters used the concentrations of elements formed in an exploding star and preserved in oceanic sediments to hypothesize that a supernova exploded near Earth just 2.5 million years ago.

The authors, led by Dr. Gunther Korschinek from the Technical University of Munich, focused their study on ferromanganese crusts collected in the Pacific Ocean. Ferromanganese crusts form on the bottom of the ocean by layers of iron- and manganese-oxides precipitating out of seawater. The studied samples started to grow some 20 million years ago at depths ranging from 5,200 feet to 3.18 miles (approximately 1.600 to 5.120 meters). The researchers measured the concentrations of iron-60 and manganese-53 isotopes in the hardened crust. They differ from Earth’s most common form of the elements by their varying number of neutrons in the atomic nucleus. Both isotopes are synthesized in large stars shortly before supernova explosions and are unstable, decaying completely after 4 to 15 million years. Their presence in sediment samples is evidence for Earth passing through a cloud of cosmic dust generated by an exploding star in – geologically speaking – recent times.

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New research suggests innovative method to analyse the densest star systems in the Universe

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New research suggests innovative method to analyse the densest star systems in the Universe
Artist’s illustration of supernova remnant Credit: Pixabay

In a recently published study, a team of researchers led by the ARC Centre of Excellence for Gravitational Wave Discovery (OzGrav) at Monash university suggests an innovative method to analyse gravitational waves from neutron star mergers, where two stars are distinguished by type (rather than mass), depending on how fast they’re spinning.


Neutron stars are extremely dense stellar objects that form when giant stars explode and die—in the explosion, their cores collapse, and the protons and electrons melt into each other to form a remnant neutron star.

In 2017, the merging of two neutron stars, called GW170817, was first observed by the LIGO and Virgo gravitational-wave detectors. This merger is well-known because scientists were also able to see light produced from it: high-energy gamma rays, visible light, and microwaves. Since then, an average of three scientific studies on GW170817 have been published every day.

In January this year, the LIGO and Virgo collaborations announced a second neutron star merger event called GW190425. Although no light was detected, this event is particularly intriguing because the two merging neutron stars are significantly heavier than GW170817, as well as previously known double neutron stars in the Milky Way.

Scientists use gravitational-wave signals—ripples in the fabric of space and time—to detect pairs of neutron stars and measure their masses. The heavier neutron star of the pair is called the ‘primary’; the lighter one is ‘secondary’.

The recycled-slow labelling scheme of a binary neutron star system

A binary neutron star system usually starts with two ordinary stars, each around ten to twenty times more massive than the Sun. When these massive stars age and run out of ‘fuel’, their lives end in supernova explosions that leave behind compact remnants, or neutron stars. Each remnant neutron star weighs around

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New Theory Suggests Tunguska Explosion Was A 656 Foot-Wide Asteroid’s Near-Miss With Earth

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In the morning of June 30, 1908, the ground trembled in Central Siberia, and a series of flying fireballs, causing a “frightful sound” of explosions, were observed in the sky above the Stony Tunguska River. Strange glowing clouds, colorful sunsets, and a weak luminescence in the night were reported as far as Europe.

Likely many thousand people in a radius of 1.500 kilometers (or 900 miles) observed the Tunguska Event. However, due to the remoteness of the affected area, eyewitness testimonies were collected only more than half of a century after the event, and most were second-hand oral accounts. In 2008, unpublished material collected by Russian ethnographer Sev’yan Vainshtein resurfaced, including some first-hand accounts of the event.

Despite its notoriety in pop-culture, hard scientific data covering the Tunguska Event is sparse. Since 1928 more than forty expeditions explored the site, taking samples from the soils, rocks, and even trees, with ambiguous results. Some seismic and air-pressure wave registrations survive, recorded immediately after the blast, and surveys of the devastated forest mapped some thirty years later.

Based on the lack of hard data, like a crater or a meteorite, and conflicting accounts, many theories of widely varying plausibility were proposed over time.

At the time of the event, international newspapers speculated about a volcanic eruption. Russian scientists, like Dr. Arkady Voznesensky, Director of the Magnetographic and Meteorological Observatory at Irkutsk where seismic waves of the explosion were recorded, speculated about a cosmic impact. In 1927, Russian mineralogist Leonid Alexejewitsch Kulik of the Russian Meteorological Institute, explained the event as the mid-air explosion of a meteorite, explaining the lack of an impact crater on the ground. In 1934, Soviet astronomers, based on Kulik’s work, proposed that a comet exploded in

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Lidar study suggests carbon storage losses greater than thought in Amazon due to losses at edge of forests

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LiDAR study suggests carbon storage losses greater than thought in Amazon due to losses at edge of forests
Graphic summary of the main results found in the work. Credit: Celso H. L. Silva Junior

An international team of researchers has found that carbon sequestering losses in the Amazon basin have been undermeasured due to omission of data representing losses at the edges of forests. In their paper published in the journal Science Advances, the group describes using lidar to estimate the carbon sequestering abilities of trees along the edges of Amazon forests.


Prior research has shown that when part of a forest in the Amazon basin is cut down, the trees that remain at the edges of the forest are not as robust as those that are situated farther in. This is because they are more exposed to pollution, pesticides, herbicides, etc. In this new effort, the researchers noticed that the reduced sequestering abilities of such trees are not included in studies of carbon sequestering losses in the Amazon basin when deforestation occurs. They suspected such losses are greater than previously thought, as evidenced by large amounts of fragmenting in the Amazon—where forest patches are surrounded by farmlands, much edging occurs.

To find out how much carbon sequestering loss has been occurring in the Amazon, the researchers flew multiple missions above the canopy edges in airplanes with lidar guns aimed downward. The technology is able to determine how healthy trees are by measuring their greenness, and thus how much carbon they are able to absorb. Back on the ground, they fed the data from the lidar guns to software applications with data describing the amount of edge forest in the Amazon basin. The software used the data from the lidar to calculate the degree of the area’s sequestering loss in total over the years 2000 to 2015—947 million tons of carbon. The researchers note that this amount

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Are there super salty lakes on Mars? Research suggests buried reservoir near south pole

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The existence of liquid water on Mars — one of the more hotly debated matters about our cold, red neighbor — is looking increasingly likely.

New research published Monday in the journal Nature Astronomy indicates that there really is a buried reservoir of super salty water near the south pole. Scientists say such a lake would significantly improve the likelihood that Mars just might harbor microscopic life of its own.

Some scientists remain unconvinced that what’s been seen is liquid water, but the latest study adds weight to a tentative 2018 finding from radar maps of the planet’s crust made by the Mars Express robot orbiter.

That research suggested that an underground “lake” of liquid water had pooled beneath frozen layers of sediment near the south pole — akin to the subglacial lakes detected beneath the Antarctic and Greenland ice sheets on Earth.

Image: Mars south polar ice cap (Bj?rn Schreiner - FU Berlin / ESA)
Image: Mars south polar ice cap (Bj?rn Schreiner – FU Berlin / ESA)

Earth’s subglacial lakes are teeming with bacterial life, and similar life might survive in liquid reservoirs on Mars, scientists have speculated.

“We are much more confident now,” said Elena Pettinelli, a professor of geophysics at Roma Tre University in Italy, who led the latest research and the earlier study. “We did many more observations, and we processed the data completely differently.”

Pettinelli and her team processed 134 observations of the region near the south pole with ground-penetrating radar from the Mars Express orbiter from 2012 to 2019, more than four times as many as before, covering a period of time more than twice as long.

They then applied a new technique to the observation data that has been used to find lakes beneath the Antarctic ice sheet, as well as an older technique used in the 2018 study.

Both methods indicate that there is