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Wooly Mammoths Went Extinct Just 5,000 Years Ago, Points DNA Evidence – News18

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The mammoth’s movements were traced through analysis of isotopes in one of its well-preserved tusks.

Scientists also claim that the horses which lived 5000 years ago in Yukon have direct relation with the horses which exist.

Scientists have found DNA traces of the ancient wooly mammoth in the soil sample taken from the Klondike region of Canada, claiming that the creature lived just until 5000 years ago and did not go extinct in North America in 7000 BC as popularly believed. The DNA which is approximately 30,000 years old was found in permafrost from Yukon and was then analysed by the scientists at McMaster University. Scientists had earlier suggested in research that the gigantic animal went extinct 9,700 years ago. According to Gizmodo, archaeologist Tyler Murchie, who specialises in ancient DNA, along with his team worked on the DNA and isolated it revealing the traces of animal and plant communities which existed 11,000 to 14,400 years ago during the unstable climatic period of Pleistocene-Holocene transition. The research was published in Nature Communications.

The recent study also revealed that the creatures did not go extinct due to overhunting by humans and instead blamed it on the rapid climatic change in the Yukon region during the early Holocene. The giant creatures like mammoths, horses and lions relied on the vast grasslands known as ‘Mammoth Steppe’ for their food which was soon overrun by shrubs and mosses.

According to Tyler Murchie, the recent revelation could be possible because of better technology which was not available during their previous conclusion. “Now that we have these technologies, we realise how much life-history information is stored in permafrost,” Murchie told Gizmodo. “The amount of genetic data in permafrost is quite enormous and really allows for a scale of ecosystem and evolutionary reconstruction that is unparalleled with other methods to date.”

Scientists also claim that the horses which lived 5000 years ago in Yukon have direct relation with the horses which exist today making them biologically a native North American mammal.

As per scientists, the data extracted from the permafrost has opened up a new window for discussions around the extinction and life-history of different species.

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Hubble telescope spots a black hole fostering baby stars in a dwarf galaxy – Space.com

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Black holes can not only rip stars apart, but they can also trigger star formation, as scientists have now seen in a nearby dwarf galaxy.

At the centers of most, if not all, large galaxies are supermassive black holes with masses that are millions to billions of times that of Earth’s sun. For instance, at the heart of our Milky Way galaxy lies Sagittarius A*, which is about 4.5 million solar masses in size. 

Astronomers have previously seen giant black holes shred apart stars. However, researchers have also detected supermassive black holes generating powerful outflows that can feed the dense clouds from which stars are born.

Video: Dwarf galaxy’s black hole triggers star formation
Related:
The strangest black holes in the universe

A Hubble Space Telescope image of the dwarf starburst galaxy Henize 2-10, shown in visible light. (Image credit: NASA/ESA/Zachary Schutte (XGI)/Amy Reines (XGI)/Alyssa Pagan (STScI))

Black hole-driven star formation was previously seen in large galaxies, but the evidence for such activity in dwarf galaxies was scarce. Dwarf galaxies are roughly analogous to what newborn galaxies may have looked like soon after the dawn of the universe, so investigating how supermassive black holes in dwarf galaxies can spark the birth of stars may in turn offer “a glimpse of how young galaxies in the early universe formed a portion of their stars,” study lead author Zachary Schutte, an astrophysicist at Montana State University in Bozeman, told Space.com.

In a new study, the scientists investigated the dwarf galaxy Henize 2-10, located about 34 million light-years from Earth in the southern constellation Pyxis. Recent estimates suggest the dwarf galaxy has a mass about 10 billion times that of the sun. (In contrast, the Milky Way has a mass of about 1.5 trillion solar masses.)

A decade ago, study senior author Amy Reines at Montana State University discovered radio and X-ray emissions from Henize 2-10 that suggested the dwarf galaxy’s core hosted a black hole about 3 million solar masses in size. However, other astronomers suggested this radiation may instead have come from the remnant of a star explosion known as a supernova.

In the new study, the researchers focused on a tendril of gas from the heart of Henize 2-10 about 490 light-years long, in which electrically charged ionized gas is flowing as fast as 1.1 million mph (1.8 million kph). This outflow was connected like an umbilical cord to a bright stellar nursery about 230 light-years from Henize 2-10’s core.

This outflow slammed into the dense gas of the stellar nursery like a garden hose spewing onto a pile of dirt, leading water to spread outward. The researchers found newborn star clusters about 4 million years old and upwards of 100,000 times the mass of the sun dotted the path of the outflow’s spread, Schutte said.

A closer view of the central region of the dwarf galaxy Henize 2-10 shows the supermassive black hole and the outflow of hot gas. (Image credit: NASA/ESA/Zachary Schutte (XGI)/Amy Reines (XGI)/Alyssa Pagan (STScI))

With the help of high-resolution images from the Hubble Space Telescope, the scientists detected a corkscrew-like pattern in the speed of the gas in the outflow. Their computer models suggested this was likely due to the precessing, or wobbling, of a black hole. Since a supernova remnant would not cause such a pattern, this suggests that Henize 2-10’s core does indeed host a black hole.

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“Before our work, supermassive black hole-enhanced star formation had only been seen in much larger galaxies,” Schutte said.

In the future, the researchers would like to investigate more dwarf galaxies with similar black hole-triggered star formation. However, this is difficult for many reasons — “systems like Henize 2-10 are not common; obtaining high quality observations is difficult; and so on,” Schutte said. However, when the James Webb Space Telescope hopefully comes online in the near future, “we will have new tools to search for these systems,” he noted.

Schutte and Reines detailed their findings in the Jan. 19 issue of the journal Nature.

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Massive Iceberg Released Over 150 Billion Tons of Fresh Water Into Ocean As It Scraped Past South Georgia – SciTechDaily

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The A68A iceberg with some smaller parts of ice that have broken off around it (November 21, 2020). Credit: MODIS image from NASA Worldview Snapshots

Scientists monitoring the giant A68A Antarctic iceberg from space reveal that a huge amount of fresh water was released as it melted around the sub-Antarctic island of South Georgia.

152 billion tonnes of fresh water – equivalent to 20 x Loch Ness or 61 million Olympic sized swimming pools, entered the seas around the sub-Antarctic island of South Georgia when the megaberg A68A melted over 3 months in 2020/2021, according to a new study. 

In July 2017, the A68A iceberg snapped off the Larsen-C Ice Shelf on the Antarctic Peninsula and began its epic 3.5 year, 4000 km journey across the Southern Ocean. At 5719 square kilometers in extent – quarter the size of Wales –, it was the biggest iceberg on Earth when it formed and the sixth largest on record. Around Christmas 2020, the berg received widespread attention as it drifted worryingly close to South Georgia, raising concerns it could harm the island’s fragile ecosystem.

Researchers from the Centre for Polar Observation and Modelling (CPOM) and British Antarctic Survey (BAS) used satellite measurements to chart the A68A iceberg’s area and thickness change throughout its life cycle. The authors show that the berg had melted enough as it drifted to avoid damaging the sea floor around South Georgia by running aground. However, a side effect of the melting was the release of a colossal 152 billion tonnes of fresh water in close proximity to the island – a disturbance that could have a profound impact on the island’s marine habitat.

A68A Iceberg Approaching the Island of South Georgia

A68A iceberg approaching the island of South Georgia (December 14, 2020). The left-hand part of the image are clouds. Credit: MODIS image from NASA Worldview Snapshots

For the first two years of its life, A68A stayed close to Antarctica in the cold waters of the Weddell Sea and experienced little in the way of melting.  However, once it began its northwards journey across Drake Passage it traveled through increasingly warm waters and began to melt.  Altogether, the iceberg thinned by 67 meters from its initial 235 m thickness, with the rate of melting rising sharply as the berg drifted in the Scotia Sea around South Georgia.

Laura Gerrish, GIS and mapping specialist at BAS and co-author of the study said:

“A68 was an absolutely fascinating iceberg to track all the way from its creation to its end. Frequent measurements allowed us to follow every move and break-up of the berg as it moved slowly northwards through iceberg alley and into the Scotia Sea where it then gained speed and approached the island of South Georgia very closely.”

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Thinning and breakage of the A68A iceberg over time. Melt rates increase sharply once the iceberg is drifting in open ocean north of the Antarctic peninsula. Iceberg thickness was derived from satellite altimetry data from Cryosat-2 and ICESat-2. Iceberg shape and size were sourced from Sentinel-1, Sentinel-3 and MODIS satellite data. Credit: Anne Braakmann-Folgmann CPOM

If an iceberg’s keel is too deep it can get stuck on the sea floor. This can be disruptive in several different ways; the scour marks can destroy fauna, and the berg itself can block ocean currents and predator foraging routes. All of these potential outcomes were feared when A68A approached South Georgia. However, this new study reveals that it collided only briefly with the sea floor and broke apart shortly afterward, making it less of a risk in terms of blockage.  By the time it reached the shallow waters around South Georgia, the iceberg’s keel had reduced to 141 meters below the ocean surface, shallow enough to avoid the seabed which is around 150 meters deep.

Nevertheless, the ecosystem and wildlife around South Georgia will certainly have felt the impact of the colossal iceberg’s visit.  When icebergs detach from ice shelves, they drift with the ocean currents and wind while releasing cold fresh meltwater and nutrients as they melt. This process influences the local ocean circulation and fosters biological production around the iceberg. At its peak, the iceberg was melting at a rate of 7 meters per month, and in total it released a staggering 152 billion tonnes of fresh water and nutrients.

[embedded content]

Anne Braakmann-Folgmann, a researcher at CPOM and PhD candidate at the University of Leeds’ School of Earth and Environment, is lead author of the study. She said:

“This is a huge amount of melt water, and the next thing we want to learn is whether it had a positive or negative impact on the ecosystem around South Georgia.

“Because A68A took a common route across the Drake Passage, we hope to learn more about icebergs taking a similar trajectory, and how they influence the polar oceans.”

The journey of A68A has been charted using observations from 5 different satellites. The iceberg’s area change was recorded using a combination of Sentinel-1, Sentinel-3, and MODIS imagery.  Meanwhile, the iceberg’s thickness change was measured using CryoSat-2 and ICESat-2 altimetry. By combining these measurements, the iceberg’s area, thickness, and volume change were determined.

Tommaso Parrinello, CryoSat Mission Manager at the European Space Agency, said:

“Our ability to study every move of the iceberg in such detail is thanks to advances in satellite techniques and the use of a variety of measurements. Imaging satellites record the location and shape of the iceberg and data from altimetry missions add a third dimension as they measure the height of surfaces underneath the satellites and can therefore observe how an iceberg melts.”

Reference: “Observing the disintegration of the A68A iceberg from space” by A. Braakmann-Folgmann, A. Shepherd, L. Gerrish, J. Izzard and A. Ridout, 10 January 2022, Remote Sensing of Environment.
DOI: 10.1016/j.rse.2021.112855

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Shattered 'alphabet soup' iceberg flushed a lot of fresh water into the ocean – Space.com

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A rogue iceberg that drifted dangerously close to an Antarctic penguin population in 2020 and 2021 released billions of tons of fresh water into the ocean during its breakup.

A new study, based on satellite data, tracks the aftermath of the once-mighty iceberg A-68a, which held the title of world’s largest iceberg for more than three years before shattering into a dozen pieces. (NASA’s Earth Observatory once dubbed the various mini-bergs “alphabet soup.”)

For a while, there were worries the iceberg might threaten a penguin-filled island called South Georgia, located about 940 miles (1,500 kilometers) northeast of the Antarctic Peninsula. Happily, that never came to pass, but the new research shows that the iceberg flooded the region with fresh water, potentially affecting the local ecosystem and providing yet another example of the effects of global warming on the oceans.

Related: Watch this giant iceberg break off from Antarctica

The research consulted data gathered by missions including Sentinel-1 (operated by European Space Agency, or ESA), Sentinel-3 (ESA), CryoSat-2 (ESA) and ICESat-2 (NASA), as well as the Moderate Resolution Imaging Spectroradiometer, or MODIS, instrument that flies aboard two NASA satellites, Aqua and Terra.

The satellite data shows that during the iceberg’s three-month melting period in late 2020 and early 2021, the former A-68a flushed into the ocean about 162 billion tons (152 billion metric tonnes) of fresh water — equivalent to 61 million Olympic-sized swimming pools, according to a press release from United Kingdom study participant University of Leeds.

“The berg had melted enough as it drifted to avoid damaging the sea floor around South Georgia by running aground,” the university stated. “However, a side effect of the melting was the release of a colossal 152 billion tonnes of fresh water in close proximity to the island — a disturbance that could have a profound impact on the island’s marine habitat.”

Fresh meltwater and nutrients tend to flow from melting icebergs. The freshwater flooding alters ocean circulation and the ocean ecosystem nearby the glacier fragment, the university noted.

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“The next thing we want to learn is whether it had a positive or negative impact on the ecosystem around South Georgia,” Leeds lead author and Ph.D. candidate Anne Braakmann-Folgmann said in the same statement. 

She noted the iceberg moved across a common ocean “highway” known as the Drake Passage, so the fate of A68-A may help understand how icebergs in that zone influence the ocean in general.

A study based on the research was published in the forthcoming March 1 issue of Remote Sensing of Environment.

Follow Elizabeth Howell on Twitter @howellspace. Follow us on Twitter @Spacedotcom and on Facebook

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