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Astronomers have detected in the stellar halo that represents the Milky Way’s outer limits a group of stars more distant from Earth than any known within our own galaxy — almost halfway to a neighboring galaxy.

The researchers said these 208 stars inhabit the most remote reaches of the Milky Way‘s halo, a spherical stellar cloud dominated by the mysterious invisible substance called dark matter that makes itself known only through its gravitational influence. The furthest of them is 1.08 million light years from Earth. A light year is the distance light travels in a year, 5.9 trillion miles (9.5 trillion km).

These stars, spotted using the Canada-France-Hawaii Telescope on Hawaii’s Mauna Kea mountain, are part of a category of stars called RR Lyrae that are relatively low mass and typically have low abundances of elements heavier than hydrogen and helium. The most distant one appears to have a mass about 70 percent that of our sun. No other Milky Way stars have been confidently measured farther away than these.

The stars that populate the outskirts of the galactic halo can be viewed as stellar orphans, probably originating in smaller galaxies that later collided with the larger Milky Way.

“Our interpretation about the origin of these distant stars is that they are most likely born in the halos of dwarf galaxies and star clusters which were later merged – or more straightforwardly, cannibalised — by the Milky Way,” said Yuting Feng, an astronomy doctoral student at the University of California, Santa Cruz, who led the study, presented this week at an American Astronomical Society meeting in Seattle.

“Their host galaxies have been gravitationally shredded and digested, but these stars are left at that large distance as debris of the merger event,” Feng added.

The Milky Way has grown over time through such calamities.

“The larger galaxy grows by eating smaller galaxies — by eating its own kind,” said study co-author Raja GuhaThakurta, UC Santa Cruz’s chair of astronomy and astrophysics.

Containing an inner and outer layer, the Milky Way’s halo is vastly larger than the galaxy’s main disk and central bulge that are teeming with stars. The galaxy, with a supermassive black hole at its center about 26,000 light years from Earth, contains perhaps 100 billion–400 billion stars including our sun, which resides in one of the four primary spiral arms that make up the Milky Way’s disk. The halo contains about 5 percent of the galaxy’s stars.

Dark matter, which dominates the halo, makes up most of the universe’s mass and is thought to be responsible for its basic structure, with its gravity influencing visible matter to come together and form stars and galaxies.

The halo’s remote outer edge is a poorly understood region of the galaxy. These newly identified stars are almost half the distance to the Milky Way’s neighboring Andromeda galaxy.

“We can see that the suburbs of the Andromeda halo and the Milky Way halo are really extended – and are almost ‘back-to-back,'” Feng said.

The search for life beyond the Earth focuses on rocky planets akin to Earth orbiting in what is called the “habitable zone” around stars. More than 5,000 planets beyond our solar system, called exoplanets, already have been discovered.

“We don’t know for sure, but each of these outer halo stars should be about as likely to have planets orbiting them as the sun and other sun-like stars in the Milky Way,” GuhaThakurta said.

© Thomson Reuters 2023


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Nasa Experiment Hints Solar Wind May Help Make Lunar Water

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Nasa Experiment Hints Solar Wind May Help Make Lunar Water

A recent study indicates that water on the lunar surface may come from the solar wind. Water—of most importance as rocket fuel—is present in lunar surface dust, or regolith, produced by meteoroids and charged particles impacting lunar rock. The researchers discovered that several of this graph had evidence of dampness, with between 200 and 300 parts per million of water and the molecule hydroxyl. The water and hydroxyl in the lunar graph were both low in deuterium, suggesting their hydrogen came from the sun, likely delivered to the moon by solar winds.

When the hydrogen particles interact with oxygen present in lunar surface rocks, water molecules arise. The results suggest that other airless bodies in the solar system may also have water on their surfaces, therefore highlighting the possibility of finding such water on the surface of other such objects.

NASA Confirms Solar Wind May Create Water on the Moon’s Surface

As per the report, it is claimed that scientists have hypothesised—since the 1960s—that the Sun is the source of elements generating water on the Moon. The idea is that water molecules would be produced by a chemical reaction set off by a stream of charged particles—the solar wind— slamming onto the lunar surface. NASA-led researchers have confirmed this prediction in the most realistic lab simulation of this process yet.

Given much of the water on the Moon is believed to be frozen in continuously shadowed areas at the poles, the result affects NASA’s Artemis astronaut activities near the South Pole.

Solar Wind Can Create Water on the Moon, NASA Lab Test Confirms

Constantly flowing from the sun, solar wind is mostly composed of protons—nuclei of hydrogen atoms deprived of their electrons. Our planet’s magnetic shield and atmosphere help most of the solar particles to avoid reaching the surface of Earth. But the Moon has no such protection. As computer models and lab experiments have shown, when protons smash into the Moon’s surface, which is made of a dusty and rocky material called regolith, they collide with electrons and recombine to form hydrogen atoms.

Scientists have discovered proof of both hydroxyl and water molecules beneath the moon’s surface. These molecules leave a chemical imprint that interacts with light on the regolith. Generally speaking, “water” refers to either one or a mix of both molecules since hydroxyl and water cannot be differentiated right now.

NASA astronaut Yeo and colleagues examined Apollo lunar samples using a customised tool employing two samples worth of dust. Their little particle accelerator battered the dust to create a copy of solar wind spanning many days.

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Tyrannosaurus Rex Fossils Are Being Horded by Private Buyers: Study

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Tyrannosaurus Rex Fossils Are Being Horded by Private Buyers: Study

A new study has found that the private trade in Tyrannosaurus rex fossils is hampering researchers’ understanding of the iconic Cretaceous predator. Thomas Carr, an associate professor of biology at Carthage College, found that there are now more scientifically valuable T. rex specimens in private or commercial ownership than in public museums and other public trusts. The private market is likely to be an underestimate, as commercial companies are discovering twice as many T. rex fossils as museums.

Private Fossil Trade Threatens T. rex Research Progress

Carr concentrated on “scientifically informative” specimens—heads, skeletons, and isolated bones—to understand exactly how the private market sets the limitations for researchers able to obtain T. rex fossils. The most valued dinosaur sold in 2024 was a Stegosaurus, which sold for $44.6 million ; Carr wants to bring attention to his work so that other researchers may investigate how the commercial market is influencing other extinct species, including the T. rex.

As per the study, it is claimed that the private trade in Tyrannosaurus rex fossils is compromising knowledge of the famous Cretaceous predator. Director of the Carthage Institute of Palaeontology in Wisconsin and associate professor of biology at Carthage College, Thomas Carr, discovered that private or commercial ownership of T. rex specimens currently numbers more than those in public museums and other public trusts. The loss of juvenile and subadult specimens is especially worrisome, as the early growth stages of T. rex are bedevilled by a poor fossil record, and the loss of them carries the heaviest scientific cost.

Study Reveals T. rex Fossils Vanishing into Private Hands

Carr published his findings, titled “Tyrannosaurus rex: An endangered species,” in the journal Palaeontologia Electronica. He targeted “scientifically informative” specimens, such as skulls, skeletons, and isolated bones, to better understand the private market’s impact on the number of T. rex fossils available to researchers. He found 61 specimens in public trusts overall and 71 specimens—including 14 juveniles—in private ownership.

Driven by the luxury fossil market spanning all types of dinosaurs, private sales of dinosaurs outside of T. rex, as he has done with the T. rex, and the most expensive auction ever for a stegosaurus for $44.6 million in 2024, Carr believes his effort will motivate other academics to investigate how the commercial market is impacting other ancient animals.

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Rare Ancient DNA Found in the Sahara Desert Unwinds the Verdant Past

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Rare Ancient DNA Found in the Sahara Desert Unwinds the Verdant Past

The silence of the Sahara desert unveils the evidence of a verdant past rooted in North African lineage, published on 2 April in the Journal Nature. The study took place in the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, together with an archaeological mission in the Sahara at Sapienza University of Rome, revealed that the two mummified individuals discovered from the Takarkori rock shelter in southwest Libya dated back over 7000 years. The findings predict the genetic history of early North African populations during the African Humid Period.

Genome Analysis

The Sahara desert was once a green savannah between 14,500 and 5000 years from the present, along the water bodies that promoted human occupation with pastoralism in the Holocene epoch. The Sahara Desert has rare DNA preservation due to its present habitat, leading to limited knowledge of genetic history. However, the Sahara was not a barren land that we know today; in fact, a green and fertile land dotted with grasslands and lakes. The study suggests that the DNA retrieval unveils a previously unknown North African ancestral lineage.

Evidence from the analysis predicts that these ancient people were different from both sub-Saharan and Eurasian groups, signalling a unique North African crowd that played a crucial role in the prehistoric period. However, the DNA contains no direct evidence of blending with neighbouring areas of that time. This, in turn, highlights the genetic isolation and importance in the history of human evolution.

The Takarkori individuals are closely related to the ancestors from Taforalt Cave, Morocco, linked with the Iberomaurusian lithic industry and predating the AHP (Analytic Hierarchy Process). However, Takarkri individuals show ten times less Neanderthal hierarchy than Valentine farmers, still significantly more than present sub-Saharan genomes. Taforalt individuals have half the Neanderthal blend of non-Africans.

Findings and Implications

The study demonstrates not just reshaping the understanding of ancient North African hierarchy but also puts strong emphasis on the importance of the Green Sahara in the past. Not just that, pastoralism flourished through cultural diffusion into a divergent, isolated North African ancestral lineage that spread in North Africa at the time of the late Pleistocene epoch. Researchers continue to explore the region, and there could be more secrets unleashed from this vast green landscape, bridging the gaps in the human origins story.

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