SPACE/COSMOS
James Webb Space Telescope reveals unexpected complex chemistry in primordial galaxy
University of Arizona
image:
This infrared image from NASA’s James Webb Space Telescope was taken by the onboard Near-Infrared Camera for the JWST Advanced Deep Extragalactic Survey, or JADES, program. The NIRCam data was used to determine which galaxies to study further with spectroscopic observations. One such galaxy, JADES-GS-z14-0 (shown in the pullout), was determined to be at a redshift of 14.3, making it the current record-holder for most distant known galaxy. This corresponds to a time less than 300 million years after the big bang.
view moreCredit: NASA, ESA, CSA, STScI, Brant Robertson (UC Santa Cruz), Ben Johnson (CfA), Sandro Tacchella (Cambridge), Marcia Rieke (University of Arizona), Daniel Eisenstein (CfA), Phill Cargile (CfA)
University of Arizona astronomers have learned more about a surprisingly mature galaxy that existed when the universe was just less than 300 million years old – just 2% of its current age.
Observed by NASA's James Webb Space Telescope, the galaxy – designated JADES-GS-z14-0 – is unexpectedly bright and chemically complex for an object from this primordial era, the researchers said. This provides a rare glimpse into the universe's earliest chapter.
The findings, published in the journal Nature Astronomy, build upon the researchers' previous discovery, reported in 2024, of JADES-GS-z14-0 as the most distant galaxy ever observed. While the initial discovery established the galaxy's record-breaking distance and unexpected brightness, this new research delves deeper into its chemical composition and evolutionary state.
The work was done as part of the JWST Advanced Deep Extragalactic Survey, or JADES, a major James Webb Space Telescope program designed to study distant galaxies.
This wasn't simply stumbling upon something unexpected, said Kevin Hainline, co-author of the new study and an associate research professor at the U of A Steward Observatory. The survey was deliberately designed to find distant galaxies, but this one broke the team's records in ways they didn't anticipate – it was intrinsically bright and had a complex chemical composition that was totally unexpected so early in the universe's history.
"It's not just a tiny little nugget. It's bright and fairly extended for the age of the universe when we observed it," Hainline said.
"The fact that we found this galaxy in a tiny region of the sky means that there should be more of these out there," said lead study author Jakob Helton, a graduate researcher at Steward Observatory. "If we looked at the whole sky, which we can't do with JWST, we would eventually find more of these extreme objects."
The research team used multiple instruments on board JWST, including the Near Infrared Camera, or NIRCam, whose construction was led by U of A Regents Professor of Astronomy Marcia Rieke. Another instrument on the telescope – the Mid-Infrared Instrument, or MIRI, revealed something extraordinary: significant amounts of oxygen.
In astronomy, anything heavier than helium is considered a "metal," Helton said. Such metals require generations of stars to produce. The early universe contained only hydrogen, helium and trace amounts of lithium. But the discovery of substantial oxygen in the JADES-GS-z14-0 galaxy suggests the galaxy had been forming stars for potentially 100 million years before it was observed.
To make oxygen, the galaxy must have started out very early on, because it would have had to form a generation of stars, said George Rieke, Regents Professor of Astronomy and the study's senior author. Those stars must have evolved and exploded as supernovae to release oxygen into interstellar space, from which new stars would form and evolve.
"It's a very complicated cycle to get as much oxygen as this galaxy has. So, it is genuinely mind boggling," Rieke said.
The finding suggests that star formation began even earlier than scientists previously thought, which pushes back the timeline for when the first galaxies could have formed after the Big Bang.
The observation required approximately nine days of telescope time, including 167 hours of NIRCam imaging and 43 hours of MIRI imaging, focused on an incredibly small portion of the sky.
The U of A astronomers were lucky that this galaxy happened to sit in the perfect spot for them to observe with MIRI. If they had pointed the telescope just a fraction of a degree in any direction, they would have missed getting this crucial mid-infrared data, Helton said.
"Imagine a grain of sand at the end of your arm. You see how large it is on the sky – that's how large we looked at," Helton said.
The existence of such a developed galaxy so early in cosmic history serves as a powerful test case for theoretical models of galaxy formation.
"Our involvement here is a product of the U of A leading in infrared astronomy since the mid-'60s, when it first started. We had the first major infrared astronomy group over in the Lunar and Planetary lab, with Gerard Kuiper, Frank Low and Harold Johnson," Rieke said.
As humans gain the ability to directly observe and understand galaxies that existed during the universe's infancy, it can provide crucial insights into how the universe evolved from simple elements to the complex chemistry necessary for life as we know it.
"We're in an incredible time in astronomy history," Hainline said. "We're able to understand galaxies that are well beyond anything humans have ever found and see them in many different ways and really understand them. That's really magic."
Journal
Nature Astronomy
Method of Research
Observational study
Subject of Research
Not applicable
Article Title
Photometric detection at 7.7 μm of a galaxy beyond redshift 14 with JWST/MIRI
Mysterious phenomenon at center of galaxy could reveal new kind of dark matter
A mysterious phenomenon at the center of our galaxy could be the result of a different type of dark matter
A mysterious phenomenon at the centre of our galaxy could be the result of a different type of dark matter.
Dark matter, the mysterious form of unobserved matter which could make up 85% of the mass of the known universe, is one of science’s biggest manhunts.
In this first of its kind study, scientists have taken a step closer to understanding the elusive mystery matter. They believe a reimagined candidate for dark matter could be behind unexplained chemical reactions taking place in the Milky Way.
Dr Shyam Balaji, Postdoctoral Research Fellow at King’s College London and one of the lead authors of the study explains, “At the centre of our galaxy sit huge clouds of positively charged hydrogen, a mystery to scientists for decades because normally the gas is neutral. So, what is supplying enough energy to knock the negatively charged electrons out of them?
“The energy signatures radiating from this part of our Galaxy suggest that there is a constant, roiling source of energy doing just that, and our data says it might come from a much lighter form of dark matter than current models consider.”
The most established theory for dark matter is that it is likely a group of particles known as ‘Weakly Interacting Massive Particles’ (WIMPs), which pass through regular matter without much interaction – making them extremely hard to detect.
However, this study, published today in Physical Review Letters, has potentially revived another type of dark matter with much, lower mass than a WIMP.
The researchers think that these tiny dark matter particles are crashing into each other and producing new charged particles in a process called ‘annihilation’. These newly produced charged particles can subsequently ionise the hydrogen gas.
Previous attempts to explain this ionisation process had relied on cosmic rays, fast and energetic particles that travel throughout the universe. However, this explanation has faced some difficulties, as energy signatures recorded from observations of the Central Molecular Zone (CMZ) where this is happening, don’t seem to be large enough to be attributed to cosmic rays. Such a process doesn’t seem to be possible with WIMPs either.
The research team were left with the explanation that the energy source causing the annihilation is slower than a cosmic ray and less massive than a WIMP.
Dr Balaji said “The search for dark matter is science’s biggest manhunt, but a lot of experiments are based on Earth. By using gas at the CMZ for a different kind of observation, we can get straight to the source. The data is telling us that dark matter could potentially be a lot lighter than we thought.”
“The search for dark matter is one of fundamental science’s most important objectives, but a lot of experiments are based on Earth, waiting with hands outstretched for the dark matter to come to them. By peering into the centre of our Milky Way, the Hydrogen gas in the CMZ is suggesting that we may be closer to identifying evidence on the possible nature of dark matter.”
This finding may simultaneously explain wider mysteries of our Galaxy, such as a specific type of X-ray observation found at the centre of the Milky Way – known as the ‘511-keV emission line’. This specific energy signature could also be due to the same low-mass dark matter colliding and producing charged particles.
Journal
Physical Review Letters
Article Publication Date
10-Mar-2025
Study: Climate change will reduce the number of satellites that can safely orbit in space
Increasing greenhouse gas emissions will reduce the atmosphere’s ability to burn up old space junk, MIT scientists report.
Massachusetts Institute of Technology
MIT aerospace engineers have found that greenhouse gas emissions are changing the environment of near-Earth space in ways that, over time, will reduce the number of satellites that can sustainably operate there.
In a study that will appear in Nature Sustainability, the researchers report that carbon dioxide and other greenhouse gases can cause the upper atmosphere to shrink. An atmospheric layer of special interest is the thermosphere, where the International Space Station and most satellites orbit today. When the thermosphere contracts, the decreasing density reduces atmospheric drag— a force that pulls old satellites and other debris down to altitudes where they will encounter air molecules and burn up.
Less drag therefore means extended lifetimes for space junk, which will litter sought-after regions for decades and increase the potential for collisions in orbit.
The team carried out simulations of how carbon emissions affect the upper atmosphere and orbital dynamics, in order to estimate the “satellite carrying capacity” of low-Earth orbit. These simulations predict that by the year 2100, the carrying capacity of the most popular regions could be reduced by 50-66 percent due to the effects of greenhouse gases.
“Our behavior with greenhouse gases here on Earth over the past 100 years is having an effect on how we operate satellites over the next 100 years,” says study author Richard Linares, associate professor in MIT’s Department of Aeronautics and Astronautics (AeroAstro).
“The upper atmosphere is in a fragile state as climate change disrupts the status quo,” adds lead author William Parker, a graduate student in AeroAstro. “At the same time, there’s been a massive increase in the number of satellites launched, especially for delivering broadband internet from space. If we don't manage this activity carefully and work to reduce our emissions, space could become too crowded, leading to more collisions and debris.”
The study includes co-author Matthew Brown of the University of Birmingham.
Sky fall
The thermosphere naturally contracts and expands every 11 years in response to the sun’s regular activity cycle. When the sun’s activity is low, the Earth receives less radiation, and its outermost atmosphere temporarily cools and contracts before expanding again during solar maximum.
In the 1990s, scientists wondered what response the thermosphere might have to greenhouse gases. Their preliminary modeling showed that, while the gases trap heat in the lower atmosphere, where we experience global warming and weather, the same gases radiate heat at much higher altitudes, effectively cooling the thermosphere. With this cooling, the researchers predicted that the thermosphere should shrink, reducing atmospheric density at high altitudes.
In the last decade, scientists have been able to measure changes in drag on satellites, which has provided some evidence that the thermosphere is contracting in response to something more than the sun’s natural, 11-year cycle.
“The sky is quite literally falling — just at a rate that’s on the scale of decades,” Parker says. “And we can see this by how the drag on our satellites is changing.”
The MIT team wondered how that response will affect the number of satellites that can safely operate in Earth’s orbit. Today, there are over 10,000 satellites drifting through low-Earth orbit, which describes the region of space up to1,200 miles, or 2,000 kilometers, from Earth's surface. These satellites deliver essential services, including internet, communications, navigation, weather forecasting, and banking. The satellite population has ballooned in recent years, requiring operators to perform regular collision-avoidance maneuvers to keep safe. Any collisions that do occur can generate debris that remains in orbit for decades or centuries, increasing the chance for follow-on collisions with satellites, both old and new.
“More satellites have been launched in the last five years than in the preceding 60 years combined,” Parker says. “One of key things we’re trying to understand is whether the path we’re on today is sustainable.”
Crowded shells
In their new study, the researchers simulated different greenhouse gas emissions scenarios over the next century to investigate impacts on atmospheric density and drag. For each “shell,” or altitude range of interest, they then modeled the orbital dynamics and the risk of satellite collisions based on the number of objects within the shell. They used this approach to identify each shell’s “carrying capacity” — a term that is typically used in studies of ecology to describe the number of individuals that an ecosystem can support.
“We’re taking that carrying capacity idea and translating it to this space sustainability problem, to understand how many satellites low-Earth orbit can sustain,” Parker explains.
The team compared several scenarios: one in which greenhouse gas concentrations remain at their level from the year 2000 and others where emissions change according to the Intergovernmental Panel on Climate Change (IPCC) Shared Socioeconomic Pathways (SSPs). They found that scenarios with continuing increases in emissions would lead to a significantly reduced carrying capacity throughout low-Earth orbit.
In particular, the team estimates that by the end of this century, the number of satellites safely accommodated within the altitudes of 200 and 1,000 kilometers could be reduced by 50 to 66 percent compared with a scenario in which emissions remain at year-2000 levels. If satellite capacity is exceeded, even in a local region, the researchers predict that the region will experience a “runaway instability,” or a cascade of collisions that would create so much debris that satellites could no longer safely operate there.
Their predictions forecast out to the year 2100, but the team says that certain shells in the atmosphere today are already crowding up with satellites, particularly from recent “megaconstellations” such as SpaceX’s Starlink, which comprises fleets of thousands of small internet satellites.
“The megaconstellation is a new trend, and we’re showing, because of climate change, we’re going to have a reduced capacity in orbit,” Linares says. “And in local regions, we’re close to approaching this capacity value today.”
“We rely on the atmosphere to clean up our debris. And if the atmosphere is changing, then the debris environment will change too,” Parker adds. “We show the long-term outlook on orbital debris is critically dependent on curbing our greenhouse gas emissions.”
This research is supported in part by the U.S. National Science Foundation, the U.S. Air Force, and the U.K. Natural Environment Research Council.
###
Written by Jennifer Chu, MIT News
Journal
Nature Sustainability
Article Title
'Greenhouse gases reduce the satellite carrying capacity of low Earth orbit'
Rising CO2 likely to speed decrease in ‘space sustainability’
University of Birmingham
Currently more than 8,000 satellites are orbiting at altitudes of between 300 and 1000 km in the Earth’s upper atmosphere – also called the thermosphere. While changes in space weather, such as coronal mass ejections and solar flares, can cause temporary changes in the density of this region, scientists at the University of Birmingham suggest the effects caused by global warming are likely to be much longer term.
This is because of the effects caused by greenhouse gases (GHGs) in the Earth’s upper atmosphere. In the lower atmosphere, GHGs are trapped by the atmosphere, and they retain infrared radiation from the Earth’s surface, leading to an overall warming effect. But this effect also pulls heat, via conduction, from the upper atmosphere. And as this region cools down, it also contracts, leaving satellites orbiting in areas where the atmosphere is less dense.
This change in density means less of an atmospheric drag on satellites – and that has important implications for their life expectancy in space. Currently, this friction is useful because it reduces the orbital energy of satellites, causing them to sink back down to Earth after several years.
Without it, satellites have the potential to stay in space for longer, increasing the chances of collision, and producing more space debris – as well as leaving less space for new satellites to be launched.
The findings, published today (10 Mar) in Nature Sustainability, provide a clear link between ground-level sustainability and space sustainability.
Lead researcher Matthew Brown, from the SERENE research group, said: “Often we think only about the ground-, or sea-level impacts of climate change, but this research demonstrates that the impacts will reach as high as space.
“The numbers of satellites in low Earth orbit is rapidly expanding and we rely heavily on them for communications, Earth observation, weather forecasting and navigation. For this reason, we need to take the long-term sustainability of space very seriously.”
Dr Brown added: “Discussions are already underway about how many satellites can be put into space at any one time, as more and more instruments are being launched into low Earth orbit. Without checking this proliferation, we are in danger of entering a ‘Kessler syndrome’, where a chain reaction of collisions causes space to become unusable.
“While technology can help these objects avoid collision, recognising the influence that the Earth’s natural environment has on our ability to operate in space is becoming increasingly important. A coordinated approach to reducing greenhouse gas emissions would ensure we can prevent the exploitation of the thermosphere and protect it for future generations.”
ENDS
For media enquiries please contact Press Office, University of Birmingham, tel: +44 (0)121 4142772: email: pressoffice@contacts.bham.ac.uk
Notes to editor:
The University of Birmingham is ranked amongst the world’s top 100 institutions. Its work brings people from across the world to Birmingham, including researchers, teachers and more than 8,000 international students from over 150 countries.
‘Greenhouse Gasses Reducing the Satellite Carrying Capacity of Low Earth Orbit’ - Parker, Brown and Linares (2025) is published in Nature Sustainability.
Journal
Nature Sustainability
Method of Research
Data/statistical analysis
Subject of Research
Not applicable
Article Title
Greenhouse Gasses Reducing the Satellite Carrying Capacity of Low Earth Orbit
Article Publication Date
10-Mar-2025
