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Ancient star explosions revealed in the deep sea – Phys.org

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Credit: Pixabay/CC0 Public Domain

A mystery surrounding the space around our solar system is unfolding thanks to evidence of supernovae found in deep-sea sediments.

Professor Anton Wallner, a at ANU, led the study which shows the Earth has been traveling for the last 33,000 years through a cloud of faintly radioactive dust.

“These could be remnants of previous supernova explosions, a powerful and super bright explosion of a star,” Professor Wallner said.

Professor Wallner conducted the research at the ANU Heavy Ion Accelerator Facility (HIAF). He also holds joint positions at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) and Technical University Dresden (TUD) in Germany.

The researchers searched through several deep-sea sediments from two different locations that date back 33,000 years using the extreme sensitivity of HIAF’s mass spectrometer. They found clear traces of the isotope iron-60, which is formed when stars die in supernova explosions.

Iron-60 is radioactive and completely decays away within 15 million years, which means any iron-60 found on the earth must have been formed much later than the rest of the 4.6-billion-year old earth and arrived here from nearby supernovae before settling on the ocean floor.

Professor Wallner previously found traces of iron-60 at about 2.6 million years ago, and possibly another at around 6 million years ago, suggesting earth had traveled through fallout clouds from nearby supernovae.

For the last few thousand years the solar system has been moving through a denser cloud of gas and dust, known as the local interstellar cloud, (LIC), whose origins are unclear. If this cloud had originated during the past few million years from a supernova, it would contain iron-60, and so the team decided to search more recent sediment to find out.

Sure enough, there was iron-60 in the sediment at extremely low levels—equating to radioactivity levels in space far below the Earth’s natural background levels—and the distribution of the iron-60 matched earth’s recent travel through the local interstellar cloud. But the iron-60 extended further back and was spread throughout the entire 33,000 year measurement period.

The lack of correlation with the ‘s time in the current local interstellar cloud seems to pose more questions than it answers. Firstly, if the cloud was not formed by a supernova, where did it come from? And secondly, why is there iron-60 so evenly spread throughout space?

“There are recent papers that suggest iron-60 trapped in might bounce around in the interstellar medium,” Professor Wallner said.

“So the iron-60 could originate from even older supernovae explosions, and what we measure is some kind of echo. More data is required to resolve these details.”

Scientists from ANU, the Australian Nuclear Science and Technology Organization, HZDR, the University of Vienna and the TU Berlin were involved in the study.

The findings have been published in the journal PNAS.


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Supernovae showered Earth with radioactive debris


More information:
A. Wallner et al. 60Fe deposition during the late Pleistocene and the Holocene echoes past supernova activity, Proceedings of the National Academy of Sciences (2020). DOI: 10.1073/pnas.1916769117

Citation:
Ancient star explosions revealed in the deep sea (2020, August 25)
retrieved 25 August 2020
from https://phys.org/news/2020-08-ancient-star-explosions-revealed-deep.html

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New Shark Research Tracks Movements of Smooth Hammerheads – DivePhotoGuide.com

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By Ian Bongso-Seldrup, September 21, 2020 @ 02:00 AM (EST)
Source: Science Daily

With overfishing driving many hammerhead species closer to the brink of extinction, a team of researchers has been focusing on determining the migration patterns of smooth hammerhead sharks (Sphyrna zygaena) in the western Atlantic Ocean in an effort to identify areas and times for management action to help in building back the depleted species.

The team tagged juvenile hammerheads off the US Mid-Atlantic coast using fin-mounted satellite tags and tracked the animals for up to 15 months. The tags reported the sharks’ movement patterns in near real time via a satellite link to the researchers.

“Getting long-term tracks was instrumental in identifying not only clear seasonal travel patterns, but importantly, also the times and areas where the sharks were resident in between their migrations,” said Ryan Logan, first author of the paper published in Frontiers in Marine Science. Logan is a PhD student at Nova Southeastern University’s Guy Harvey Research Institute and SOSF SRC and the Save Our Seas Foundation Shark Research Center (SOSF SRC).

Logan and his coworkers found that the sharks migrate between two seasonally resident areas: coastal waters off New York in the summer and off North Carolina in the winter. Identifying these habitats is vital for ultimately designating the areas as “Essential Fish Habitat”—with the accompanying limitations on fishing and development.

The high-resolution data also revealed that the hammerheads spent a lot of time in the Mid-Atlantic Shark Area (MASA) in the winter, starting in December. The MASA zone is closed to bottom longline fishing between January 1st and July 31st to protect dusky sharks, so beginning the closure of the zone in December would further reduce the fishing mortality of juvenile smooth hammerheads.   

Check out the tracks of various shark species, including smooth hammerheads, at Guy Harvey Research Institute’s dedicated website.

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Venus is a Russian planet — say the Russians – CNN Philippines

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(CNN)— No longer confined to territories here on Earth, Russia has now staked its claim on Venus, saying it is a “Russian planet.”

This week, Dmitry Rogozin, head of the Russian space corporation Roscosmos, revealed that the country plans to send its own mission to Venus in addition to “Venera-D,” the planned joint mission with the US, the Russian state news agency TASS reported.

Rogozin was addressing reporters at the HeliRussia 2020 exhibition, an international expo of the helicopter industry in Moscow.

“Resuming Venus exploration is on our agenda,” he told reporters Tuesday.

“We think that Venus is a Russian planet, so we shouldn’t lag behind,” he said.

“Projects of Venus missions are included in the united government program of Russia’s space exploration for 2021-2030.”

The statement came the day after scientists revealed that a gas on Earth called phosphine had also been detected in the atmosphere of Venus.

Venus is similar in size to Earth and is our closest planetary neighbor, but it spins backward compared to other planets.

The study authored by Cardiff University professor Jane Greaves and her colleagues was published Monday in the journal Nature Astronomy.

The discovery of phosphine on Venus elevates it to an area of interest worth exploring in our solar system alongside the ranks of Mars and “water world” moons like Enceladus and Europa, Seager said.

“Our hoped-for impact in the planetary science community is to stimulate more research on Venus itself, research on the possibilities of life in Venus’ atmosphere, and even space missions focused to find signs of life or even life itself in the Venusian atmosphere,” Seager said.

According to the European Space Agency, the Russians do have significant experience when it comes to Venus.

Its website states: “Between 1967-1984 Venusian studies carried out in Russia were at the forefront of international research into this planet.

“Since then, Russia has still preserved its unique expertise in designing and developing landing craft for Venus and continues to define scientific tasks for those craft.”

This story was first published on CNN.com, “Venus is a Russian planet — say the Russians.”

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Florida man survives alligator attack while walking dog, gets 65 stitches – FOX 5 Atlanta

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Florida man out walking his dog was attacked by an alligator and nearly dragged into a canal behind his home.

Mark Johnson, 61, said he was walking along the canal last Sunday in Port. St. Lucie with his 8-year-old golden retriever when he saw a gator turn towards them.

Johnson said his foot got stuck in mud moments before he saw “the lunge” as the alligator grabbed his leg.

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“He starts clamping down pretty tight, and he started to pull, and the next thing I do … I poke [the gator] through the eye,” he told WPLG-TV.

Johnson told Treasure Coast Newspapers that after he stuck his finger in the gator’s eye, the reptile immediately let go and swam away.

After limping home with blood dripping from his leg, Johnson’s wife cleaned the wound and wrapped the leg in a towel before taking him to a hospital.

Johnson said he suffered 12 puncture wounds that required 60 stitches, plus another five to mend the index finger that was cut on the gator’s eye socket.

The Florida Fish and Wildlife Conservation Commission said a trapper captured the gator involved in the attack on Wednesday.

AUSTRALIAN RANGERS TRAP 770-POUND CROCODILE NEAR OUTBACK TOURIST SPOT

Officials said the alligator measured 8 feet, 6 inches and weighed nearly 250 pounds. The reptile has since been relocated to an alligator farm.

Johnson said that even though the reptile was trying to drag him into the water, staying calm was what helped him survive.

“You cannot panic,” he told the paper. “I bass fish all the time, too. I’ll reach down and lift up the bass with my hand. I just got lucky.”

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Johnson said when he’s able to walk his dog again, he’ll probably carry some sort of weapon for protection.

The Associated Press contributed to this report.

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