Connect with us

Science & Tech

Astronomers discover new phenomenon as white dwarf star switches ‘on and off’ in 30 minutes

Published

on

The discovery was based on observations from a NASA satellite searching for alien planets, and described as “extraordinary” by a team of astronomers at Durham University and their partners across the world.

Astronomers have discovered a new cosmic phenomenon in which a white dwarf star has been switching “off and on”, with its brightness dipping and strengthening in just 30 minutes.

The discovery was based on observations from a NASA satellite searching for alien planets, and described as “extraordinary” by a team of astronomers at Durham University and their partners across the world.

Initially they believed the fluctuations were something that was interfering with the way the white dwarf, which is part of a binary system, was feeding from a companion star – but they did not expect the cause to be as unique as it turned out to be.

As the flow of material from a donor star to the main white dwarf is governed by gravity it should remain relatively constant, so there was no obvious reason why the star’s luminosity would change on such short timescales as were being seen.

The researchers realised what was happening was something that had never been seen before – repeated and rapid reconfigurations of the white dwarf’s surface magnetic field.Advertisement

The binary system known as TW Pictoris is about 1,400 light years away from Earth.

Normally, when its white dwarf is “on”, the star feeds from its companion, glowing brightly into space – but sometimes this stops and the star dims, turning “off”.

This has been seen before, but it does not usually happen so quickly.

According to the research published in the journal Nature Astronomy, the reason is because the white dwarf has an unusually fast magnetic field which is spinning so rapidly that it blocks the stream of matter from reaching the main star.

Lead author Dr Simone Scaringi, who works at Durham’s Centre for Extragalactic Astronomy, said: “The brightness variations seen in accreting white dwarfs are generally relatively slow, occurring on timescales of days to months.

“To see the brightness of TW Pictoris plummet in 30 minutes is in itself extraordinary as it has never been seen in other accreting white dwarfs,” he said.

Dr Scaringi explained to Sky News: “In general the accretion process in accreting white dwarfs is relatively smooth and does not have any short-term ‘gaps’ in brightness variations.

“What generally happens in these types of systems is that the donor star in orbit around the white dwarf keeps feeding the accretion disk.

“As the accretion disk material slowly sinks closer towards the white dwarf it generally becomes brighter, and eventually makes it onto the white dwarf surface.

“It is known that in some systems the donor stars stops feeding the disk,” he added, although he noted scientists have not yet figured out why this happens, but when it does the disk remains bright for a while as the star “drains” the material that was previously there.

“It then takes the disk about one to two months to drain most of the material, something we saw happen in different accreting white dwarfs,” Dr Scaringi explained.

“Once the amount of material has nearly drained out entirely, this is when so-called ‘magnetic-gating’ acts: the spinning magnetospheric barrier of the white dwarf prevents left-over disk material from simply accreting smoothly, but instead regulates the amount that lands onto the white dwarf in ‘fits and starts’.

“As it takes months to drain a disk out, seeing TW Pictoris drop in brightness in 30 mins was totally unexpected,” he added.

“What we think may be happening in TW Pictoris is that instead of the disk being drained out so fast, we are seeing some sort of reconfiguration of the white dwarf magnetic field, which promptly pushes the inner-disk edge outwards, and thus makes it fainter for some time until the disk is able to push back once again,” he explained.

“This really is a previously unrecognised phenomenon,” Dr Scaringi said.

“Because we can draw comparisons with similar behaviour in the much smaller neutron stars it could be an important step in helping us to better understand the process of how other accreting objects feed on the material that surrounds them and the important role of magnetic fields in this process.”

Continue Reading
Click to comment

Leave a Reply

Your email address will not be published. Required fields are marked *

Science & Tech

Meta: UK competition regulator tells Facebook owner to sell GIF library Giphy

Published

on

The investigation into the acquisition has been acrimonious, with Meta previously being fined £50m by the CMA for deliberately refusing to comply with the regulator’s inquiries.

Facebook’s owner Meta has been issued a legally binding order to sell the GIF library Giphy after an investigation found the takeover “could harm social media users and UK advertisers”.

The Competition and Markets Authority (CMA) launched an in-depth investigation into the deal in April after raising a number of concerns. It subsequently warned of the potential forced sale in August.

Giphy – a website for making and sharing animated images, known as GIFs – was acquired by Facebook (now Meta) in May last year to integrate the GIFs with Instagram, but the CMA has now ordered the acquisition to be unravelled.

Sky News understands Facebook intends to appeal the CMA’s decision. It has four weeks to do so and the appeal would go to a the Competition Appeal Tribunal, which is independent of the CMA.

Meta could potentially challenge that ruling in the UK courts, but only on points of law.Advertisement

Facebook has rebranded to Meta
Image:Facebook’s parent company was renamed Meta last month

Stuart McIntosh, who chaired the independent inquiry into the acquisition, said: “The tie-up between Facebook and Giphy has already removed a potential challenger in the display advertising market.

“Without action, it will also allow Facebook to increase its significant market power in social media even further, through controlling competitors’ access to Giphy GIFs.

“By requiring Facebook to sell Giphy, we are protecting millions of social media users and promoting competition and innovation in digital advertising,” Mr McIntosh explained.

The investigation into the acquisition has seen points of acrimony, with Meta being fined a record £50m by the CMA for deliberately refusing to comply with the regulator’s inquiries.

Meta argued that it has been in compliance with the competition watchdog’s primary orders at all times.

At the time of the fine, the company complained that the CMA delayed for seven months a request to amend these orders which was eventually agreed in what the company described as nearly an identical manner to what had been requested.

When Facebook first merged with Giphy it terminated the image library’s advertising services, “removing an important source of potential competition” according to the CMA.

This was considered “particularly concerning given that Facebook controls nearly half of the £7 billion display advertising market in the UK”.

However in Meta’s response to the preliminary findings, the social media giant described the acquisition as a simple vertical merger and said that Giphy was financially troubled and suggested that its attempts to monetise its GIF library for display advertising were unsuccessful.

“If GIF paid alignments were the promising business model that the CMA believes they are, then one would expect to encounter them in the real-world at scale… Yet that is not the case,” the response stated.

According to the regulator, the acquisition potentially also enabled the social media giant to change the terms of access to the GIF library for its competitors.

“For example, Facebook could require Giphy customers, such as TikTok, Twitter and Snapchat, to provide more user data in order to access Giphy GIFs.

“Such actions could increase Facebook’s market power, which is already significant,” the regulator said.

In its review of the merger, the CMA said it risked entrenching Meta’s market dominance, noting that its platforms (Facebook, Instagram, and WhatsApp) already accounted for 73% of all user time spent on social media in the UK.

A spokesperson for Meta said: “We disagree with this decision. We are reviewing the decision and considering all options, including appeal. Both consumers and Giphy are better off with the support of our infrastructure, talent, and resources.

“Together, Meta and Giphy would enhance Giphy’s product for the millions of people, businesses, developers and API partners in the UK and around the world who use Giphy every day, providing more choices for everyone.”

Continue Reading

Health

COVID-19: Mild and moderate cases during pregnancy doesn’t harm babies’ brains, finds study

Published

on

Parents should be reassured, there is “no evidence that a maternal SARS-CoV-2 infection has any effect on the brain development of the unborn child” say scientists.

Mild and moderate coronavirus infections in pregnant women appear to have no effect on the brain of the developing foetus according to a new study.

Two years into the COVID-19 pandemic “there is evidence that pregnant women are more vulnerable” to the coronavirus, according to a study presented to the Radiological Society of North America (RSNA).

The new study aims to identify what the possible consequences are for the unborn child if the mother is infected during pregnancy, and to study the likelihood of the virus being passed on to the foetus.

“Women infected with SARS-CoV-2 during pregnancy are concerned that the virus may affect the development of their unborn child, as is the case with some other viral infections,” said Dr Sophia Stoecklein, senior author of the study.Advertisement

“So far, although there are a few reports of vertical transmission to the foetus, the exact risk and impact remain largely unclear,” added Dr Stoecklein, from the department of radiology at Ludwig Maximilian University of Munich.

“The aim of our study was to fill this gap in knowledge regarding the impact of a maternal SARS-CoV-2 infection on foetal brain development,” she added.

MRI scans were used to study 33 pregnant women who were infected with COVID-19 during their pregnancy, with the women roughly 28 weeks into the pregnancies at the time of the scan.

The scans were evaluated by radiologists with years of experience in foetal MRIs who found that the brain development in the assessed areas was age-appropriate in all of the children, with no findings indicating any infection affected the brains.

“In our study, there was no evidence that a maternal SARS-CoV-2 infection has any effect on the brain development of the unborn child,” Dr Stoecklein said. “This fact should help to reassure affected parents.”

But she cautioned that only mothers with mild to moderate symptoms who were not hospitalised were included in the study, meaning the impact of “severe infection on brain development in the foetus has not been conclusively determined”.

Continue Reading

Science & Tech

Earth’s water may have come from the Sun, new research finds

Published

on

Researchers at the University of Glasgow say there is evidence that particles emitted by the Sun created water on the surface of dust grains on asteroids which hit Earth.

The origin of Earth’s water continues to be debated by scientists – whether it was here when the planet formed or if it had an extraterrestrial source.

But new research points the finger at a previously uncounted point of origin: the Sun at the centre of our solar system.

According to astronomers, solar radiation may have created water on the surface of dust grains carried on asteroids that smashed in to our planet billions of years ago.

Alaska has been hit by an earthquake. File pic: iStock.
Image:Water covers 70% of the Earth’s surface – but scientists aren’t sure where it came from

Water covers more than 70% of our planet’s surface, but the exact source has puzzled scientists for decades if not longer.

A new study published in the journal Nature Astronomy suggests it has found a source which perfectly matches the isotopic signature of water on Earth.Advertisement

The research, led by scientists at the University of Glasgow, used a process called atom probe tomography to analyse different asteroid samples – some of which carry water and others which orbit too close to the Sun to do so.

Dr Luke Daly, from the University of Glasgow and the study’s lead author, said: “The solar winds are streams of mostly hydrogen and helium ions which flow constantly from the Sun out into space.

“When those hydrogen ions hit an airless surface like an asteroid or a space-borne dust particle, they penetrate a few tens of nanometres below the surface, where they can affect the chemical composition of the rock.

“Over time, the ‘space weathering’ effect of the hydrogen ions can eject enough oxygen atoms from materials in the rock to create H2O – water – trapped within minerals on the asteroid.

“Crucially, this solar wind-derived water produced by the early solar system is isotopically light.”

“That strongly suggests that fine-grained dust, buffeted by the solar wind and drawn into the forming Earth billions of years ago, could be the source of the missing reservoir of the planet’s water,” Dr Daly added.Thousands of people could still be killed by a completely unpredictable asteroid impact

Professor Bland at Curtin University explained that the existing theory that water was carried to Earth in the final stages of its formation by water-carrying asteroids didn’t hold up to examination.

“Previous testing of the isotopic ‘fingerprint’ of these asteroids found they, on average, didn’t match with the water found on Earth meaning there was at least one other unaccounted for source,” he said.

“Our research suggests the solar wind created water on the surface of tiny dust grains and this isotopically lighter water likely provided the remainder of the Earth’s water,” added the professor, who works at the Space Science and Technology Centre at Curtin University.

“This new solar wind theory is based on meticulous atom-by-atom analysis of miniscule fragments of an S-type near-Earth asteroid known as Itokawa, samples of which were collected by the Japanese space probe Hayabusa and returned to Earth in 2010.

“Our world-class atom probe tomography system here at Curtin University allowed us to take an incredibly detailed look inside the first 50 nanometres or so of the surface of Itokawa dust grains, which we found contained enough water that, if scaled up, would amount to about 20 litres for every cubic metre of rock,” added Professor Bland.

Continue Reading

Trending Now