Monday, October 07, 2024

Nobel Prize: Victor Ambros, Gary Ruvkun win medicine award

DW
7/10/24

Victor Ambros and Gary Ruvkun have been awarded the Nobel Prize in physiology or medicine for their research into microRNA.

Victor Ambros and Gary Ruvkun were announced as the joint recipients of the 2024 Nobel Prize in medicine or physiology on Monday
Image: Steffen Trumpf/dpa/picture alliance


American scientists Victor Ambros and Gary Ruvkun have been jointly awarded the Nobel Prize in medicine or physiology for their shared discovery of microRNA and the role it plays in post-transcriptional gene regulation.

At the announcement by the Nobel Assembly at the Karolinska Institutet in Sweden on Monday morning, Nobel Committee vice-chair Professor Olle Kämpe described the discovery of microRNA as "a tiny molecule that has opened a new field in gene regulation."

Though the pair worked in separate labs, their joint research focus led to them combining their resources to expand knowledge of microRNA and its role.

"The seminal discovery of microRNA has introduced a new and unexpected mechanism of gene regulation," said Kämpe.

"MicroRNAs are important for our understanding of embryological development, normal cell physiology and diseases such as cancer. As an example, tumors often perturb microRNA networks to grow."

Mutations in the roundworm species Caenorhabditis elegans were the first signs of microRNA in living organisms
.Image: Washington University School of Medicin/dpa/picture alliance


Nobel Prize microRNA discovery started with a tiny roundworm

This Nobel Prize is all about foundational genetics.

At the heart of what makes a living organism function is the ability of double-stranded DNA to be translated by single-stranded RNA molecules. These "messenger" RNA (mRNA) create an "information molecule" from DNA and move into a cell’s protein factory — a ribosome — where amino acids align to this template and then fold into specialized proteins.

These proteins are the building blocks of all living organisms. But mutations or variations to genes can cause changes in function — often benign, but potentially disease-causing.

This general pathway to organism metabolism has been understood for a long time, but as Kämpe posed, "What determines that only the right genes are transcribed into messenger RNA and then translated into the right, tissue-specific proteins at the right time?"

The answer starts with one specific organism, the roundworm species Caenorhabditis elegans. Despite its size, the roundworm has 20,000 genes that code for proteins — about the same number as a human, making it an ideal lab ‘model’ for physiological research.

Different mutations to C. elegans genes were found to cause growth changes. One triggered excessive growth via a repeating developmental pathway. Another restricted growth due to a different gene variation.

Ambros found the enlarging "lin-4" variant in 1993, with Ruvkun isolating the "lin-14" mutation present in the miniature worms a year later. What wasn’t clear was how these variations interacted and influenced cell regulation. The pair joined forces to find the answer.

A micro discovery leads to big implications for science

Ambros and Ruvkun found their respective mutations interacted — specifically, that a sequence of code on the lin-4 gene corresponded to part of a lin-14 sequence.

This was the critical moment when microRNA was determined to exist, as a distinct form of RNA.

"At this point they had discovered a novel and unexpected mechanism of gene regulation — microRNA," said Kämpe. "For a long time, however, microRNA was believed to be an oddity peculiar to C. elegans."

It required more evidence to confirm their findings.

It came in 2000, when Ruvkun found another gene — "let-7" — which was found not just in roundworm, but in humans and most animals.

Many microRNAs, it turns out, are highly conserved across animals, plants and fungi, meaning that they are largely unchanged from species-to-species and across hundreds of millions of years of biological evolution.

More than 1,000 microRNA genes have been found in humans.

"Every microRNA regulates several genes," said Kämpe. "And each mRNA is regulated by many distinct microRNAs, creating a robust system for gene regulation."


When did RNA enter the public spotlight?

RNA was thrust into the public consciousness with the rise of RNA-based vaccine technology at the height of the COVID-19 pandemic.

These vaccine products could be developed relatively quickly by creating imitation proteins based on small sections of genetic code from the SARS-CoV-2 virus.

When used in a vaccine, these proteins provide a non-disease-causing target for the human immune system to find and create antibodies ready for the real virus.

Katalin Kariko and Drew Weissman were awarded last year’s prize for their work developing mRNA vaccine technology.

However while last year’s prize was very much in recognition of work that had led to direct medical applications, this year’s is more research focused.

"This year’s prize is definitely a physiology prize," said Professor Gunilla Karlsson Hederstam, chair of the Nobel Committee for Physiology or Medicine. "Last year, of course, [was] much a more applied discovery that was translated into vaccine development, so two quite different prizes.

"Although there are no very clear applications available yet, understanding them, knowing that they exist, understanding their regulatory networks is always the first step."

Joint laureate in the 2024 Nobel Prize for Physiology, Victor Ambros laughs with colleagues.
Image: Steven Senne/AP/picture alliance


Why type of products are being developed which utilize microRNA technology?

So while this year’s prize is very much focused on discovery rather than application, the realization of the Ambros-Ruvkun research may not be far away. There are currently several vaccine-type products in clinical trial stage for cancer, cardiovascular and other diseases that use microRNA technology.

The challenge is hitting the right target. Take a cancer cell. There may be a specific gene that a vaccine needs to address, but microRNAs regulate many different genes. The risk is that a product may act more like a bulldozer than a scalpel.

"But there might be ways around that," said Kämpe, "Tumors quite often perturb the microRNA networks and they can do that by deleting the genes or mutating the genes that process the microRNA.

"In [this] case there are promising first tests to see if you can modulate the RNA-binding proteins, but to deliver microRNAs to cells and think you get one effect, I think will be very difficult."

Two more Nobel science prizes will be awarded this week, with the physics laureate to be revealed on Tuesday, and chemistry prize on Wednesday.

Joint laureate in the 2024 Nobel Prize for Physiology, Gary Ruvkun.
Image: Steven Senne/AP/picture alliance


What is the history of the Nobel Prize in Physiology or Medicine?

This year's Prize, set at 11 million Swedish kronor (about $1.06 million USD), is yet another recognition of genetic discovery.

Arthur Kornberg and Severo Ochoa were recognized in 1959 for identifying the synthesis mechanisms of DNA and RNA, while the famed trio Crick, Watson and Wilkins were awarded the prize in 1952 for unravelling the DNA Double Helix.

Fire and Mello (2006), and Karikó and Weissman (2023) have also had their work on RNA recognized.

Famed Austrian neurologist and founder of psychoanalysis Sigmund Freud (1856-1939) was nominated for his work in Physiology and Medicine but was never named as a recipient.

At 31, Canadian surgeon and pharmacologist Frederick G. Banting is the youngest recipient of the Prize in Physiology or Medicine. He was recognized in 1923 for his discovery of insulin.

The American pathologist Francis Peyton Rous is the oldest, receiving his award in 1966 aged 87 for his discovery of tumor-inducing viruses.

The prize has been declined once. In 1939, Gerhard Domagk was prevented by Germany's Nazi Government from receiving his award for his discovery of an antibiotic against Streptococcus infections. He was later able to receive his diploma and medal in 1947.

Edited by Wesley Dockery


What is microRNA? Nobel-winning discovery explained

Agence France-Presse
October 7, 2024 

Victor Ambros and Gary Ruvkun won the Nobel for medicine for their discovery of microRNA © Jonathan NACKSTRAND / AFPn/liVictor Ambros and Gary Ruvkun won the Nobel for medicine for their discovery of microRNA © Jonathan NACKSTRAND / AFP

The Nobel Prize in Medicine was awarded on Monday to two US scientists for discovering microRNA, a previously unknown type of genetic switch which is hoped can pave the way for new medical breakthroughs.

But while several treatments and tests are under development using microRNAs against cancer, heart disease, viruses and other illnesses, none have actually yet reached patients.

And the world paid little attention when the new Nobel laureates Victor Ambros and Gary Ruvkun revealed their discovery decades ago, thinking it was just "something weird about worms", Cambridge University geneticist Eric Miska told AFP.

Here is an explainer about how exactly these tiny genetic switches work inside our bodies.

What is microRNA?

Each cell in the human body has the same set of instructions, called DNA. Some turn into brain cells, while others become muscles.

So how do the cells know what to become? The relevant part of the DNA's instructions is pointed to via a process called gene regulation.

Ribonucleic acid (RNA) normally serves as a messenger. It delivers the instructions from the DNA to proteins, which are the building blocks of life that turn cells into brains -- or muscles.

Miska gave the example of the messenger RNA vaccines rolled out against Covid-19 during the pandemic, which insert a message with new instructions to build proteins that block viruses.


Nobel prize for medicine 2024 © Valentina BRESCHI, Sylvie HUSSON, Lise KIENNEMANN, Thierno TOURE / AFP

But the two new Nobel winners Ambros and Ruvkun discovered a whole new type of gene regulator that had previously been overlooked by science.

Rather than being the messenger which relays information, microRNA instead acts as a switch to turn other genes off and on.


"This was a whole new level of control that we had totally missed," said Miska, who has worked on microRNA for two decades, including with the new Nobel laureates.

"The discovery of microRNAs brought an additional level of complexity by revealing that regions that were thought to be non-coding play a role in gene regulation," French researcher Benoit Ballester told AFP.


What did the Nobel winners do?


Back in the 1980s, Ambros and Ruvkun had been working separately on how genes interact in one-millimetre-long roundworms called C.elegans.

When they compared their work, it led to the discovery of microRNA. Ambros revealed the finding in a 1993 paper.

"Nobody really paid much attention," Miska said, explaining that most scientists at the time thought it only applied to worms.


Then in 2000, Ruvkun published research showing that microRNA is present right across the animal kingdom, including in humans and even some viruses.

"This was not just something weird that worms do, but in fact all animals and plants are totally dependent for development and normal function on them," Miska said.

More than a thousand genes that respond to microRNAs are now believed to be in the human body.

How could this help us?

There are numerous new treatments and tests using microRNA that are undergoing trials but none have been made widely available.

"Though there are no very clear applications available yet in microRNAs, understanding them, knowing that they exist, understanding their counter-regulatory networks, is always the first step," the Karolinska Institute's Gunilla Karlsson Hedestam told journalists in Stockholm.


MicroRNAs are particularly promising for fighting cancer because some of these switches "act as a tumour suppressor, so they put a brake on cells dividing inappropriately," Miska said.

Others, meanwhile, induce "cells to divide, which can lead to cancer", he added.

Because many viruses use microRNAs, several antiviral drugs are at varying stages of development, including for hepatitis C.


One complicating factor has been that microRNAs can be unstable.

But scientists also hope they can be used as a test called a "biomarker", which could reveal what type of cancer a patient could be suffering from, for example.
What next?


It also appears probable that microRNAs could be involved in the evolution of our species, Miska said.

While human brains are difficult to study, Miska hoped future research will discover more.

© 2024 AFP

Albania: Clashes as protesters call on government to resign

The protesters demand that the current leftist government be replaced by a caretaker cabinet. This comes as Tirana prepares to start discussions with the European Union over membership in the bloc.

Protesters in Albania demand the current government's replacement
Image: Hameraldi Agolli/AP/dpa/picture alliance


Albanian police fired teargas to disperse opposition protesters who gathered in the streets of the capital Tirana to call on longtime leftist Prime Minister Edi Rama to resign.

Thousands of protesters took to the streets, calling out chants such as: "Down with the dictatorship."

The protests, organized by the right-wing opposition, demand the replacement of the ruling government with a technocratic caretaker cabinet ahead of next year's parliamentary election.

What happened in the protests?

More than 1,000 police officers were deployed across Albania's capital Tirana ahead of the protests.

Protesters hurled petrol bombs at several government buildings, burning posters of the prime minister. Police said ten officers were hurt, while some protesters were seen with streaming eyes from tear gas.

Local media reported some were taken to hospital.

Police intensified the use of tear gas as protesters approached the parliament building.

This comes after years of corruption accusations against Prime Minister Rama's Socialists, mostly from the conservative opposition.

"[Rama] should give up, he should resign, he should go away, he should go in jail for the rest of his life," one protester told the Reuters news agency.

In office since 2013, Rama has won three consecutive elections.

Albania's opposition has been holding protests at parliament against the current government
Image: Florion Goga/REUTERS

What else has prompted the recent protests?

Former Prime Minister Sali Berisha's Democratic Party has also been holding protests at parliament in the past week after party official Ervin Salianji was imprisoned over "giving false testimony."

The party says the case is politically motivated.

The Democrats are also seeking Berisha's release from house arrest. The former prime minister has been confined to his house since last year on charges of "passive corruption."

Opposition leader Sali Berisha has been under house arrest for almost a yearImage: Armando Babani/AP/picture alliance

Both the US and the European Union (EU) have urged the opposition to engage in dialogue with the government, saying violence won't help the country integrate into the bloc.

Later this month, Albania will start discussions with the EU as to how the country aligns with it on the rule of law, the functioning of democratic institutions and the fight against corruption.

This comes after the bloc's 2020 decision to start full membership negotiations with Tirana.

ftm/ (Reuters/AP)

Albania’s opposition protests and demands a caretaker Cabinet


BY LLAZAR SEMINI
October 7, 2024

TIRANA, Albania (AP) — Opposition supporters in Albania protested again Monday, demanding that the government be replaced by a technocratic caretaker Cabinet before next year’s parliamentary election.

The conservative opposition has long accused Prime Minister Edi Rama’s Socialists of corruption, manipulating earlier voting and usurping powers of the judiciary and others.

The Democratic Party of former Prime Minister Sali Berisha has been holding protests at parliament in the past week after a colleague was convicted of slander and imprisoned in a case they consider as being politically motivated. Ervin Salianji has appealed his conviction to the Supreme Court.

The Democrats, who have staged sometimes violent protests against the government since 2013, also seek Berisha’s release from house arrest, where he was put during an investigation of alleged corruption.

A few thousand protesters gathered in front of the main government building in Tirana shouting “Down with the dictatorship” and “Berisha, Berisha.” After briefly clashing with police, they hurled Molotov cocktails.

Outside the governing Socialist Party headquarters, they again hurled Molotov cocktails and burned a poster of the prime minister, who leads the party. They then did the same outside the Interior Ministry and city hall.
Outside parliament, police used tear gas to move them away.

Hundreds of police officers had taken up positions to protect government institutions. Police said traffic was blocked on many streets downtown.


Police said 10 officers were hurt by Molotov cocktails, pyrotechnic items and hard objects. Some protesters were seen with streaming eyes from tear gas and a few were taken to a hospital, according to local media.

The Democrats’ secretary-general, Flamur Noka, ended the protest by pledging that the “civil disobedience” would continue.

The U.S. Embassy had warned its citizens to stay away from the protest.

The U.S. and European Union have urged the opposition to resume dialogue with the government, saying violence won’t help the country integrate into the 27-nation EU bloc.


In 2020, the EU decided to launch full membership negotiations with Albania, and later this month Tirana will start discussions with the bloc on how the country aligns with EU stances on the rule of law, the functioning of democratic institutions and the fight against corruption.
___

Follow Llazar Semini at https://x.com/lsemini

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An opposition protester holds a flare during an anti-government rally set up by the opposition, in Tirana, Albania, Monday, Oct. 7, 2024. (AP Photo/Hameraldi Agolli)

An opposition supporter protests during a rally, in Tirana, Albania, Monday, Oct. 7, 2024. (AP Photo/Hameraldi Agolli)

Fire burns behind a riot police cordon during an anti-government rally set up by the opposition, in Tirana, Albania, Monday, Oct. 7, 2024. (AP Photo/Hameraldi Agolli)

Opposition supporters scuffle with riot police during a anti-government rally, in Tirana, Albania, Monday, Oct. 7, 2024. (AP Photo/Hameraldi Agolli)

Fire burns behind a riot police cordon and in front of a poster depicting the Albania Prime minister Edi Rama during an anti-government rally set up by the opposition, in Tirana, Albania, Monday, Oct. 7, 2024. (AP Photo/Hameraldi Agolli)

An opposition supporter waves a wooden stick to riot police during a anti-government rally, in Tirana, Albania, Monday, Oct. 7, 2024. (AP Photo/Hameraldi Agolli)

An Albania police man washes his face during an anti-government rally set up by the opposition, in Tirana, Albania, Monday, Oct. 7, 2024. (AP Photo/Hameraldi Agolli)

 SPACE/COSMOS

Europe's Hera spacecraft blasts off to investigate asteroid already rammed by NASA

The European Space Agency's Hera spacecraft set off on Monday on its two-year journey towards a small asteroid already rammed by NASA to test whether potentially planet-threatening asteroids can be bumped off course by a well-timed launch.

Issued on: 07/10/2024 -

This artist's illustration obtained from NASA on November 4, 2021 shows the DART spacecraft from behind prior to impact at the Didymos binary system. Two years' on, Hera has been launched to investigate the results of DART's mission to ram the asteroid.
 © NASA/Johns Hopkins APL via AFP

A spacecraft blasted off Monday to investigate the scene of a cosmic crash.

The European Space Agency's Hera spacecraft rocketed away on a two-year journey to the small, harmless asteroid rammed by NASA two years ago in a dress rehearsal for the day a killer space rock threatens Earth. Launched by SpaceX from Cape Canaveral, it’s the second part of a planetary defense test that could one day help save the planet.

The 2022 crash by NASA's Dart spacecraft shortened Dimorphos' orbit around its bigger companion, demonstrating that if a dangerous rock was headed our way, there’s a chance it could be knocked off course with enough advance notice.

Scientists are eager to examine the impact’s aftermath up close to know exactly how effective Dart was and what changes might be needed to safeguard Earth in the future.

"The more detail we can glean the better as it may be important for planning a future deflection mission should one be needed,” University of Maryland astronomer Derek Richardson said before launch.

Researchers want to know whether Dart – short for Double Asteroid Redirection Test – left a crater or perhaps reshaped the 500-foot (150-meter) asteroid more dramatically. It looked something like a flying saucer before Dart’s blow and may now resemble a kidney bean, said Richardson, who took part in the Dart mission and is helping with Hera.

04:22  SCIENCE © FRANCE 24

Dart’s wallop sent rubble and even boulders flying off Dimorphos, providing an extra kick to the impact’s momentum. The debris trail extended thousands of miles (more than 10,000 kilometers) into space for months.

Some boulders and other debris could still be hanging around the asteroid, posing a potential threat to Hera, said flight director Ignacio Tanco.

“We don't really know very well the environment in which we are going to operate,” said Tanco. "But that's the whole point of the mission is to go there and find out.”

European officials describe the $400 million (363 million euro) mission as a “crash scene investigation.”

Hera "is going back to the crime site and getting all the scientific and technical information,” said project manager Ian Carnelli.

Carrying a dozen science instruments, the small car-sized Hera will need to swing past Mars in 2025 for a gravity boost, before arriving at Dimorphos by the end of 2026. It's a moonlet of Didymos, Greek for twin, a fast-spinning asteroid that's five times bigger. At that time, the asteroids will be 120 million miles (195 million kilometers) from Earth.

Controlled by a flight team in Darmstadt, Germany, Hera will attempt to go into orbit around the rocky pair, with the flyby distances gradually dropping from 18 miles (30 kilometers) all the way down to a half-mile (1 kilometer). The spacecraft will survey the moonlet for at least six months to ascertain its mass, shape and composition, as well as its orbit around Didymos.

Before the impact, Dimorphos circled its larger companion from three-quarters of a mile (1,189 meters) out. Scientists believe the orbit is now tighter and oval-shaped, and that the moonlet may even be tumbling.

Two shoebox-sized Cubesats will pop off Hera for even closer drone-like inspections, with one of them using radar to peer beneath the moonlet’s boulder-strewn surface. Scientists suspect Dimorphos was formed from material shed from Didymos. The radar observations should help confirm whether Didymos is indeed the little moon’s parent.

The Cubesats will attempt to land on the moonlet once their survey is complete. If the moonlet is tumbling, that will complicate the endeavor. Hera may also end its mission with a precarious touchdown, but on the larger Didymos.

Neither asteroid poses any threat to Earth – before or after Dart showed up. That’s why NASA picked the pair for humanity’s first asteroid-deflecting demo.

Leftovers from the solar system’s formation 4.6 billion years ago, asteroids primarily orbit the sun between Mars and Jupiter in what’s known as the main asteroid belt, where millions of them reside. They become near-Earth objects when they’re knocked out of the belt and into our neck of the woods.

NASA’s near-Earth object count currently tops 36,000, almost all asteroids but also some comets. More than 2,400 of them are considered potentially hazardous to Earth.

(AP)

Mission to probe smashed asteroid launches despite hurricane

Miami (AFP) – Europe's Hera probe successfully launched Monday on a mission to inspect the damage done by a NASA spacecraft that smashed into an asteroid during the first test of Earth's planetary defences.


Issued on: 07/10/2024 - 
The asteroid Dimorphos was successfully deflected by humanity's first test of Earth's planetary defences © Handout / ASI/NASA/AFP/File

Despite fears that an approaching hurricane could delay the launch, the probe blasted off on a SpaceX rocket into cloudy skies from Cape Canaveral in the US state of Florida just before 11:00 am local time (1500 GMT).

Hera's mission is to investigate the aftermath of NASA's Double Asteroid Redirection Test (DART), which deliberately crashed into the Dimorphos asteroid in 2022 roughly 11 million kilometres (6.8 million miles) from Earth.

The fridge-sized DART spacecraft successfully knocked the asteroid well off course, demonstrating that humanity may no longer be powerless against potentially planet-killing asteroids that could head our way.

The European Space Agency (ESA) said that Hera will conduct what it has dubbed a "crime scene investigation".

"Hera will gather the data we need to turn kinetic impact into a well-understood and repeatable technique on which all of us may rely one day," ESA chief Josef Aschbacher said on the agency's broadcast of the launch.

The tense liftoff on SpaceX's Falcon 9 rocket was met with applause from teams on the ground.
Dimorphos may prove to have been a loose pile of rubble held together by gravity © Handout / NASA/Jons Hopkins APL/AFP/File

"We had a lot of tears -- and outside in the public event, people were jumping around and spilling their beers," ESA broadcast host Matthew Russell said.

Around an hour after liftoff, Hera then separated from the rocket in space, beginning its two-year journey towards Dimorphos.

There was more applause minutes later when the team on the ground received the first signal from the spacecraft, indicating a successful launch.
Hurricane, rocket anomaly

The launch had been put into doubt by the intensifying Hurricane Milton, with SpaceX warning on Sunday that there was only a 15 percent chance of a launch.

Milton is the latest hurricane to hit the Gulf of Mexico after Hurricane Helene, which has killed at least 230 people since striking Florida late last month.

Hurricane Milton has been classified as "an extremely dangerous category 4 hurricane" and is expected to slam into the state by mid-week.

NASA said it will delay the launch of its Europa Clipper mission, which had been scheduled from Cape Canaveral on Thursday, due to "anticipated hurricane conditions" as Milton moves east across Florida over the week.

The successful DART mission deflected the asteroid © Jonathan WALTER, Vincent LEFAI, Sophie RAMIS / AFP/File

Hera's launch had also faced a potential delay due to an anomaly involving a Falcon 9 rocket during the launch of SpaceX's Crew-9 astronaut mission late last month.

But on Sunday, the US Federal Aviation Administration gave the last-minute green light, saying the nature of the problem posed little risk for Hera.

Next year, Hera is planned to get a gravitational boost as it flies past Mars, arriving near Dimorphos in December 2026 to begin its six-month investigation.

Dimorphos, which is actually a moonlet orbiting its big brother Didymos, never posed a threat to Earth.

After DART's impact, Dimorphos shed material to the point where its orbit around Didymos was shortened by 33 minutes -- proof that it was successfully deflected.

Analysis of the DART mission has suggested that rather than being a single hard rock, Dimorphos was more a loose pile of rubble held together by gravity.

"The consequence of this is that, instead of making a crater" on Dimorphos, DART may have "completely deformed" the asteroid, said Hera's principal investigator Patrick Michel.
Nothing heading our way

The 363-million-euro ($400 million) mission will be equipped with two nanosatellites.

One will land on Dimorphos and probe inside the asteroid with radar, a first on such an asteroid. The other will study its composition from farther out.

An asteroid wider than a kilometre (0.6 miles) -- which could trigger a global catastrophe on a scale that wiped out the dinosaurs -- is estimated to strike Earth every 500,000 years or so.

An asteroid around 140 metres (460 feet) wide -- which is a little smaller than Dimorphos but could still take out a major city -- hits our home planet around every 20,000 years.

There are also no known 140-metre asteroids on a collision course with Earth -- but only 40 percent of those space rocks are believed to have been identified.

© 2024 AFP

Winds of change: James Webb Space Telescope reveals elusive details in young star systems


Astronomers have discovered new details of gas flows that sculpt planet-forming disks and shape them over time, offering a glimpse into how our own solar system likely came to be.



University of Arizona

Artist’s impression of a planet-forming disk surrounding a young star 

image: 

This artist’s impression of a planet-forming disk surrounding a young star shows a swirling "pancake" of hot gas and dust from which planets form. Using the James Webb Space Telescope, the team obtained detailed images showing the layered, conical structure of disk winds – streams of gas blowing out into space.

view more 

Credit: National Astronomical Observatory of Japan (NAOJ)




Every second, more than 3,000 stars are born in the visible universe. Many are surrounded by what astronomers call a protoplanetary disk – a swirling "pancake" of hot gas and dust from which planets form. The exact processes that give rise to stars and planetary systems, however, are still poorly understood.

A team of astronomers led by University of Arizona researchers has used NASA's James Webb Space Telescope to obtain some of the most detailed insights into the forces that shape protoplanetary disks. The observations offer glimpses into what our solar system may have looked like 4.6 billion years ago.

Specifically, the team was able to trace so-called disk winds in unprecedented detail. These winds are streams of gas blowing from the planet-forming disk out into space. Powered largely by magnetic fields, these winds can travel tens of miles in just one second. The researchers' findings, published in Nature Astronomy, help astronomers better understand how young planetary systems form and evolve. 

According to the paper's lead author, Ilaria Pascucci, a professor at the U of A's Lunar and Planetary Laboratory, one of the most important processes at work in a protoplanetary disk is the star eating matter from its surrounding disk, which is known as accretion.

"How a star accretes mass has a big influence on how the surrounding disk evolves over time, including the way planets form later on," Pascucci said. "The specific ways in which this happens have not been understood, but we think that winds driven by magnetic fields across most of the disk surface could play a very important role."

Young stars grow by pulling in gas from the disk that's swirling around them, but in order for that to happen, gas must first shed some of its inertia. Otherwise, the gas would consistently orbit the star and never fall onto it. Astrophysicists call this process "losing angular momentum," but how exactly that happens has proved elusive.

To better understand how angular momentum works in a protoplanetary disk, it helps to picture a figure skater on the ice: Tucking her arms alongside her body will make her spin faster, while stretching them out will slow down her rotation. Because her mass doesn't change, the angular momentum remains the same.

For accretion to occur, gas across the disk has to shed angular momentum, but astrophysicists have a hard time agreeing on how exactly this happens. In recent years, disk winds have emerged as important players funneling away some gas from the disk surface – and with it, angular momentum – which allows the leftover gas to move inward and ultimately fall onto the star.

Because there are other processes at work that shape protoplanetary disks, it is critical to be able to distinguish between the different phenomena, according to the paper's second author, Tracy Beck at NASA's Space Telescope Science Institute.

While material at the inner edge of the disk is pushed out by the star's magnetic field in what is known as X-wind, the outer parts of the disk are eroded by intense starlight, resulting in so-called thermal winds, which blow at much slower velocities.

"To distinguish between the magnetic field-driven wind, the thermal wind and X-wind, we really needed the high sensitivity and resolution of JWST (the James Webb Space Telescope)," Beck said.

Unlike the narrowly focused X-wind, the winds observed in the present study originate from a broader region that would include the inner, rocky planets of our solar system – roughly between Earth and Mars. These winds also extend farther above the disk than thermal winds, reaching distances hundreds of times the distance between Earth and the sun.  

"Our observations strongly suggest that we have obtained the first images of the winds that can remove angular momentum and solve the longstanding problem of how stars and planetary systems form," Pascucci said.

For their study, the researchers selected four protoplanetary disk systems, all of which appear edge-on when viewed from Earth.

"Their orientation allowed the dust and gas in the disk to act as a mask, blocking some of the bright central star's light, which otherwise would have overwhelmed the winds," said Naman Bajaj, a graduate student at the Lunar and Planetary Laboratory who contributed to the study.

By tuning JWST's detectors to distinct molecules in certain states of transition, the team was able to trace various layers of the winds. The observations revealed an intricate, three-dimensional structure of a central jet, nested inside a cone-shaped envelope of winds originating at progressively larger disk distances, similar to the layered structure of an onion. An important new finding, according to the researchers, was the consistent detection of a pronounced central hole inside the cones, formed by molecular winds in each of the four disks.

Next, Pascucci's team hopes to expand these observations to more protoplanetary disks, to get a better sense of how common the observed disk wind structures are in the universe and how they evolve over time.

"We believe they could be common, but with four objects, it's a bit difficult to say," Pascucci said. "We want to get a larger sample with James Webb, and then also see if we can detect changes in these winds as stars assemble and planets form."

For a complete list of authors, please see the paper, "The nested morphology of disk winds from young stars revealed by JWST/NIRSpec observations," Nature Astronomy (DOI 10.1038/s41550-024-02385-7). Funding for this work was provided by NASA and the European Research Council.

Composite image showing nested morphology of disk winds emissions of protoplanetary disk HH30.