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Stone found in Sahara Desert is first proof of universe’s most energetic event, say researchers

ScientiFix, our weekly feature, offers you a summary of the top global science stories of the week, with links to their sources.

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New Delhi: Researchers from the University of Johannesburg believe Hypatia, a stone found in the Sahara desert in 1992, could be the first tangible evidence of a Supernova type Ia explosion – a type of star explosion that is one of the most energetic events in the universe.

Uncovering a series of highly unusual clues in the chemical composition of a small fragment of the stone, the researchers have pieced together a timeline of Hypatia’s origin dating back to the early stages of the formation of Earth, the Sun and the other planets in our Solar System.

Their hypothesis: The origin of Hypatia can be traced back to when a red giant star (a star in its death stages) collapsed into a white dwarf star (stars with medium to high mass).

After the collapse that would have taken place inside a gigantic dust cloud (nebula), the white dwarf star found itself in a binary system with a second star, orbiting a common centre of mass. The “hungry” white dwarf star eventually “ate” the other star and at some point, exploded, causing a Supernova type Ia explosion inside the nebula.

Once the cooling process was complete, gas atoms – residue of the Supernova type Ia explosion –  started sticking to particles of the nebula, resulting in the formation of Hypatia’s parent rock. 

At some point, it started hurtling towards our planet but the heat of entry into Earth’s atmosphere, combined with the pressure of impact in the Great Sand Sea in south-western Egypt, shattered Hypatia’s parent rock. Read more.


Also Read: Scientists capture first-ever image of supermassive black hole at the centre of Milky Way


Farming on the Moon

Scientists at the University of Florida have managed to grow plants in lunar soil, a first step for farming on the Moon if and when humans plan an extended lunar stay.

Although plants grown in lunar soil are not as robust as those grown in earthen soil, the team is hoping to figure out a way to grow more nutrient-rich plants on the Moon by studying how these plants respond to lunar samples.

For their experiment, scientists used Arabidopsis thaliana, which is used as a model organism for research into all areas of plant biology due to its small size and ease of growth. Native to Eurasia and Africa, it is a distant relative of mustard greens and other cruciferous vegetables like broccoli, cauliflower, and Brussels sprouts.

Using samples collected during the Apollo 11, 12, and 17 missions, the team sowed seeds in trays, with one gram of regolith (lunar dust) for each plant. The trays, stored inside terrarium boxes, were kept in a clean room where they were given water and a nutrient solution daily.

And just two days later, the Arabidopsis thaliana started to sprout. Read more.

‘Night-time’ solar power

In a major breakthrough, researchers from the University of New South Wales have managed to produce electricity from ‘night-time’ solar power – the heat radiated by Earth at night. 

Solar power warms up the planet during the day in the form of sunlight and at night, this same energy radiates back into the vast, cold void of outer space in the form of infrared light.

It was by harnessing the emission of this infrared light – using a semiconductor device called a thermoradiative diode, composed of materials found in night-vision goggles – that researchers were able to generate power.

Although the amount of power generated at this stage is very small, around 100,000 times less than that supplied by a solar panel, researchers believe this is just the beginning and there is scope for improvement. Read more.

Ancient humans’ South-Asian link

Scientists have discovered an ancient molar they believe belongs to a young Denisovan girl who lived about 164,000 years ago in a cave in what is now Laos, according to a new study. This discovery is evidence that ancient humans, previously known only to dwell in caves in Siberia and China, also lived in South-East Asia.

The study shows that Denisovans – a group of humans that went extinct around 20,000 years ago – lived in a wide range of environments and latitude and were able to adapt to extreme conditions ranging from the cold mountains of Russia and Tibet to the tropical forests of South-East Asia. 

So far, researchers have discovered only five Denisovan fossils – three upper molars, a finger bone and a jawbone. This is why there is very little known or understood about them.

Past research shows that ancestors of modern humans split about 700,000 years ago from the lineage that gave rise to Neanderthals and Denisovans. However, genetic analysis of fossils of these extinct lineages reveal that the possibility of them having interbreed with modern humans cannot be ruled out.

The exact places where Denisovans may have lived is also a subject of heated debate since all of their fossils found so far have been traced to mainland Asia, but genetic research suggests that populations in Oceania and Southeast Asian Islands, too, may have Denisovan roots. Read more.

The sounds of aurora

Researchers at Finland’s Aalto University have been studying auroral sounds for many years. Their recordings of sounds made by the Aurora Boreaolis (northern lights) have revealed that this phenomenon is much more common than was believed earlier and occurs even in the absence of visible northern lights. 

In 2016, the team was able to link recordings of crackling and popping sounds during an auroral event with temperature profiles. The data demonstrated that these lights are sometimes associated with sounds, which result from electrical discharges across a temperature inversion layer about 70 meters above the ground.

Temperature inversion layers are areas where the air above the ground is warmer than the air below it.

Researchers recorded these sounds at night, when no northern lights were visible. They then compared the recordings with measurements of geomagnetic activity, and found that a strong correlation was evident since the 60 best candidate sounds in terms of data quality were all linked with changes in the geomagnetic field.

These recordings show that auroral sounds occur even in the absence of visible northern lights, which means that the phenomenon is more common than was believed earlier. Read more.

(Edited by Amrtansh Arora)


Also Read: Climate change spurred collapse of 17th-century kingdom in Tibet, says study on crop yield


 

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