Discovered, an Earth-sized exoplanet outside our solar system that could be ‘covered in volcanoes’

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

LP 791-18 d, shown here in an artist's concept, is an Earth-size world about 90 light-years away | Photo NASA’s Goddard Space Flight Center/Chris Smith (KRBwyle)

New Delhi: Astronomers have found an Earth-like exoplanet that could be covered with volcanoes. The planet, named LP 791-18 d, is about 90 light-years away from us.

The planet could undergo volcanic outbursts as often as Jupiter’s moon ‘Io’ — the most volcanically active body in our solar system.

Researchers from the University of Montreal found and studied the planet using data from National Aeronautics and Space Administration’s (NASA) TESS (Transiting Exoplanet Survey Satellite) and retired Spitzer Space Telescope, as well as a suite of ground-based observatories. The observations were published in the journal Nature this week. 

The planet orbits a small red dwarf star in the southern constellation crater. The team estimates it’s only slightly bigger and heavier than Earth. It is tidally locked, which means one of its sides always faces its star. 

This is the third planet to be discovered in this star system called LP 791-18 b and c. The inner planet b is about 20 per cent bigger than Earth. The outer planet c is about 2.5 times Earth’s size and more than seven times its mass.

During each orbit, planets d and c pass very close to each other. Each close pass by the more massive planet c produces a gravitational tug on planet d, making its orbit somewhat elliptical. 

On this elliptical path, planet d is slightly deformed every time it goes around the star. These deformations can create enough internal friction to substantially heat the planet’s interior and produce volcanic activity at its surface. This is similar to what happens on Jupiter’s moon Io.

Planet d sits on the inner edge of the habitable zone, the traditional range of distances from a star where scientists hypothesise liquid water could exist on a planet’s surface. 

If the planet is as geologically active, as the research team suspects, it could maintain an atmosphere. Temperatures could drop enough on the planet’s night side for water to condense on the surface. Read More

Evolution of modern humans 

Scientists have now proposed a new model of human evolution that overturns the previous beliefs which said a single African population gave rise to all humans on the planet. 

For a study published in the journal Nature this week, researchers from McGill University and the University of California Davis tested genetic material of current populations in Africa and compared it with the existing fossil evidence of early Homo sapiens populations there.

The team included newly sequenced genomes from 44 modern Nama individuals from southern Africa — an indigenous population known to carry exceptional levels of genetic diversity compared with the other modern groups. 

The new model suggests that the earliest population split among early humans, that is detectable in contemporary populations, occurred 120,000 to 135,000 years ago. This is after two or more weakly genetically differentiated Homo sapiens populations had been mixing for hundreds of thousands of years.

After the population split, people still migrated between the stem populations. 

This offers a better explanation of genetic variation among individual humans and human groups than previous models. Read More.

Key Greenland glacier retreating 

Petermann is one of Greenland’s largest marine-terminating glaciers. Like most glaciers that discharge ice into the ocean, Petermann periodically sheds large icebergs. 

But contact with the sea also means warmer water has been melting the glacier’s ice from below, with implications for sea-level rise, according to the study in Proceedings of the National Academy of Sciences published earlier this month.

A pair of images, acquired with the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite, shows the retreat of the glacier’s floating ice tongue. 

Petermann is generally thinning, retreating, and its flow is accelerating. The acceleration stretches and thins the glacier, which makes it prone to fractures, or rifts, that can break and form an iceberg. 

Several large icebergs have broken from Petermann during the years spanned by these images, including a 251 sq-km berg in 2010, and a 32 sq-km berg in 2012. 

Rifting and periodic iceberg calving are normal parts of an outlet glacier’s life cycle, even in northwest Greenland. Still, these two events reduced the ice tongue by one-third.

Meanwhile, warming ocean waters are helping melt the floating ice tongue from below. This melting might be especially significant along the grounding line — the area where the glacier loses contact with the bedrock and begins to float. Read More

Novel approach to treat autism

Scientists have identified a potential method for treating Fragile X syndrome (FXS)— a leading cause of autism spectrum disorders. The disorder is characterised by an inherited repeat of a certain sequence of DNA of the FMR1 gene.

FMR1 makes a protein called FMRP that is needed for brain development, but in people born with FXS there is a reduced expression of this protein, leading to developmental delays, learning disabilities, and social and behavioural problems. 

The disorder affects 1 in 3,000 boys and 1 in 6,000 girls, according to researchers.

In a study published in the journal Cell Friday, researchers from Massachusetts General Hospital (MGH)  generated models derived from the cells of patients with FXS and exposed them to different laboratory conditions. They discovered the conditions that induce full FMR1 reactivation. 

The team is now extending the technology to patient neurons and to the brain in animal models. Read More

‘E-skin’ can mimic human gestures

Researchers have developed an electronic skin that can mimic the same process that causes a finger, toe or limb to move when poked or scalded. 

The technology could lead to the development of more realistic prosthetics that would give their users a sense of touch, or help to restore sensation in people whose skin has been damaged.

The ‘e-skin’ developed at Stanford University in California can also transmit electrical signals to the brain to allow the wearer to ‘feel’ pressure, strain or changes in temperature.

The latest work, published in the journal Science, describes a thin, flexible sensor that can transmit a signal to the part of the motor cortex in a rat’s brain that causes its leg to twitch when the e-skin is pressed or squeezed.

To make a fully soft e-skin, the research team developed a flexible polymer for use as a dielectric — a thin layer in a semiconductor device that determines the strength of the signal and the voltage needed to run the device. 

The researchers then used the dielectric to make stretchy, flexible arrays of transistors, combined into a sensor that was thin and soft like skin. Read More

(Edited by Richa Mishra)