Radio Signals from the Edge of Extreme Stars

The illustration shows a pulsar (red sphere) and its strong magnetic field (yellow lines). As the stellar remnant rotates, narrow beams of radio waves (cones) sweep across the sky and become detectable as regular signals for observers on Earth. The beams originate close to the magnetic poles (yellow cones) but may also arise from a region farther out (blueish cone), as the new study suggests. The proportions and colours are not realistic and are for illustrative purposes only. © MPIfR

---

To the point

• Astronomers analysed the radio and gamma-ray emission of nearly 200 extremely fast rotating pulsars.


• One-third of these millisecond pulsars show radio signals coming from two or more separate regions. Some of the isolated radio pulses line up perfectly with the emission of gamma-rays.


• The authors suggest that millisecond pulsars produce radio waves not just close to their surfaces, but also in a region far out, where magnetic fields sweep around at nearly the speed of light to keep up with the star’s rotation.

---

A team of German and Australian astronomers found evidence that some of the fastest-spinning stars in the Universe broadcast radio waves from far beyond where scientists thought possible.

Pulsars are ultra-dense, rapidly spinning, and highly magnetised remnants of dead stars. They act like cosmic lighthouses, sending out regular pulses of radio waves and sometimes gamma rays in beams that sweep across the sky. A special class called millisecond pulsars spins hundreds of times per second and is among the most precise clocks in the Universe. For decades, astronomers believed that a pulsar’s radio signals are only produced close to the star’s surface, near its magnetic poles. The new study, published in the current issue of Monthly Notices of the Royal Astronomical Society, challenges that long-held idea.

An unexpected discovery

Michael Kramer from the Max Planck Institute for Radio Astronomy (MPIfR) in Germany and Simon Johnston from Australia’s national science agency, CSIRO, analysed radio observations of nearly 200 millisecond pulsars and compared them with gamma-ray data. The duo discovered something striking in this large data set: About one-third of millisecond pulsars show radio signals coming from two or more completely separate regions, with emission free gaps in between. In comparison, this behaviour occurs in only about 3% of slower rotating pulsars. Even more striking, many of these isolated radio pulses line up perfectly with gamma-ray flashes detected by NASA’s Fermi satellite — suggesting that both signals are produced in the same extreme region of space.

A surprising conclusion

To explain these patterns, the authors propose that millisecond pulsars produce radio waves in two very different places: one close to the star’s magnetic poles, as traditionally assumed, and another in a swirling “current sheet” just beyond the so-called light cylinder. Located farther out than the magnetic poles, the light cylinder marks the boundary where magnetic fields sweep around at nearly the speed of light to keep up with the star’s rotation. Depending on the observer's perspective on the pulsar, one sees radio emission from either near the surface, from far out, or from both regions. This gives rise to the unusual, broken-up radio profiles that puzzled astronomers for years. The “current sheet” of charged particles is already thought to be responsible for gamma-ray emission. The alignment of radio waves and gamma-rays can be explained through this shared place of origin.

The animation demonstrates the importance of perspective: Depending on the angle at which an observer sees the pulsar (red sphere), they will detect radio waves (cones) from near the magnetic poles, from a more distant region, or from both. This influences the appearance of the observed radio signals. Credit: Michael Kramer - Video

Exciting prospects and open questions

This discovery has several important consequences: More pulsars may be detectable than previously thought, because radio emission may not be limited to a narrow cone from close to the magnetic poles. Instead, it spreads over a wider range of directions. The finding also helps explain why astronomers often struggle to interpret the polarisation (orientation) of radio waves from millisecond pulsars. Furthermore, it suggests that nearly all gamma-ray millisecond pulsars also emit radio waves, even if those signals may be faint or difficult to detect. This raises new challenges for theory: Scientists now need to explain how stable radio pulses can be generated so far away from the star, in an extreme and turbulent environment.

“Millisecond pulsars are key tools for studying gravity, dense matter, and even gravitational waves. Understanding where their signals come from — and why they look the way they do — is essential for using them as precision instruments”, explains Michael Kramer. Co-author Simon Johnston adds: “This study shows that these tiny, fast-spinning stars are even more complex and surprising than we thought, broadcasting from both their surfaces and from the very edge of their magnetic reach.”

Source: Max Planck for Radio Astronomy/Press Releases

---

Contacts:

Prof. Dr. Michael Kramer
Executive Director and Head of “Fundamental Physics in Radio Astronomy“ Research Dept.
Tel: +49 228 525-299
mkramer@mpifr-bonn.mpg.de
Max Planck Institute for Radio Astronomy, Bonn

Dr. Simon Johnston

Senior Principal Research Scientist, Australia Telescope National Facility
Contact via Rachel Rayner, CSIRO communications
Tel: +61 2 9372-4172 rachel.rayner@csiro.au
CSIRO, Australia’s national science agency

Dr. Nina Brinkmann
Press and Public Relations
Tel: +49 228 525-399
brinkmann@mpifr-bonn.mpg.de
Max Planck Institute for Radio Astronomy, Bonn

---

Original publication

Michael Kramer and Simon Johnston
Radio emission from beyond the light cylinder in millisecond pulsars
Monthly Notices of the Royal Astronomical Society 547 (2026)

DOI

---

Graphics

• pulsar 6.6 MB
• pulsar_annotated 2.46 MB

---

'Space Archaeology' Reveals First Dynamic History of a Giant Spiral Galaxy

An artist's impression shows the giant spiral galaxy NGC 1365 as it collides and merges with a smaller companion galaxy, stirring up star formation and redistributing gas and heavy elements. Using a new "space archaeology" technique that reads the chemical fingerprints in the galaxy’s gas, astronomers have reconstructed how NGC 1365 grew over 12 billion years.Credit: Melissa Weiss/CfA. High resolution image

Six views of the spiral galaxy NGC 1365, as extracted from its spectro-photometric data cube, generated by the TYPHOON survey. On the far left is a broadband image of the galaxy balancing B (blue), V (visual) and R (red) continuum images to approximate what the human eye would see. The next image is a narrow-band image extracted from the TYPHOON data cube centered on the H alpha line of ionized hydrogen. Individual HII regions, powered by hot high-luminosity OB stars, are clearly seen outlining the two massive spiral arms. The next three images are slices centered on other diagnostic emission lines (Nitrogen, Sulfur, and a composite of all three diagnostic emission lines). The final panel shows the color-coded velocity field of NGC 1365. Credit: B. Madore, The Observatories, Carnegie Institution for Science. High resolution image

---

For the first time, astronomers used galactic archaeology techniques to trace the chemical "fossil record" of a galaxy outside the Milky Way

Cambridge, MA (March 23, 2026) — A team of astronomers led by the Center for Astrophysics | Harvard and Smithsonian have for the first time used galactic archaeology, the study of detailed chemical fingerprints in deep space, to trace the history of a galaxy outside the Milky Way.

The study, published today in the journal Nature Astronomy, demonstrates a new way to reconstruct the evolution of distant galaxies, and opens up a new field of astronomy, called "extragalactic archaeology."

"This is the first time that a chemical archaeology method has been used with such fine detail outside our own galaxy," says Lisa Kewley, lead author, Harvard professor, and director of the Center for Astrophysics. "We want to understand how we got here. How did our own Milky Way form, and how did we end up breathing the oxygen that we're breathing right now?"

Using data from the TYPHOON survey on the Irénée du Pont telescope at the Las Campanas Observatory, the scientists examined the nearby spiral galaxy NGC 1365, whose wide disc shape is oriented so we can see it face-on from Earth. They achieved resolution sharp enough to separate and study individual star-forming clouds in the galaxy.

When they're young, hot stars shine brightly in the ultraviolet, and that intense light can excite nearby gases, Kewley explains. Each element, such as oxygen, in the gas then produces bright, narrow lines of light.

Astronomers know that the centers of galaxies usually have more heavy elements, including oxygen, while the outer parts have less. The oxygen pattern is shaped by several factors, including where and when stars formed and exploded as supernovae, how gas has flowed in or out of the galaxy, and past mergers with other galaxies.

By measuring how the oxygen patterns change across a galaxy and comparing with state-of-the-art galaxy simulations in the Illustris Project, the astronomers traced how the galaxy grew and merged with other galaxies over 12 billion years of cosmic time. The simulations track the motion of gas, star formation, black holes, and chemical evolution in galaxies from shortly after the Big Bang to the present day.

The astronomers searched through simulations of about 20,000 galaxies and found one that closely matched NGC 1365's observed properties, from which they inferred the galaxy's likely merger and growth history.

> The astronomers found that NGC 1365's central region formed early in the galaxy's history and developed a large amount of oxygen. The gas further out built up over 12 billion years through collisions with smaller dwarf galaxies. The gas in the outer spiral arms of the galaxy probably formed relatively late, over the last few billion years, and was also fed by gas and stars from merging dwarf galaxies.

"It's very exciting to see our simulations matched so closely by data from another galaxy," said Lars Hernquist, Mallinckrodt Professor of Astrophysics at Harvard and a CfA astronomer. "This study shows that the astronomical processes we model on computers are shaping galaxies like NGC 1365 over billions of years."

Overall, the study shows NGC 1365 began as a small galaxy and slowly grew into a giant spiral via multiple mergers with smaller dwarf galaxies.

The astronomers establish extragalactic archaeology as a powerful newapproach and tool that demonstrates that chemical fingerprints in a galaxy's gas can reveal its history, said Kewley.

"This study shows really well how you can produce observations to be directly aided by theory," she said. "I think it's also going to impact how we work together as theorists and observers, because this project was 50 percent theory and 50 percent observations, and you couldn't do one without the other. You need both to come to these conclusions."

By studying galaxies like NGC 1365, which bears similarities to the Milky Way, astronomers can gain insight into how typical or unusual our own galaxy may be and the different pathways galaxies can take to reach their current states.

"Do all spiral galaxies form in a similar way?" asked Kewley. "Are there differences between their formation? Where is their oxygen distributed now? Is our Milky Way different or unique in any way? Those are the questions we want to answer."

Source: Harvard-Smithsonian Center for Astrophysics (CfA)/News

---

Original paper: DOI 10.1038/s41550-026-02808-7

The assembly history of NGC 1365 through chemical archaeology.Nature Astronomy. Lisa J. Kewley, Kathryn Grasha, Alex Garcia, Paul Torrey, Jeff Rich, S. Hemler, Qian-Hui Chen, Peixin Zhu, Mark Seibert, Lars Hernquist, Barry Madore.

---

About the Center for Astrophysics | Harvard & Smithsonian

The Center for Astrophysics | Harvard & Smithsonian is a collaboration between Harvard and the Smithsonian designed to ask, and ultimately answer, humanity's greatest unresolved questions about the nature of the universe. The CfA is headquartered in Cambridge, MA, with research facilities across the U.S. and around the world.

---

Authors include:

Lisa Kewley, Director and Scientist Center for Astrophysics | Harvard & Smithsonian; and Paine Professor of Astronomy at Harvard University

Kathryn Grasha, Research School for Astronomy & Astrophysics and ARC Centre of Excellence for All-Sky Astrophysics in 3 Dimensions (ASTRO 3D), Australian National University

Alex Garcia, Department of Astronomy, University of Florida and Department of Astronomy, University of Virginia; Paul Torrey, Department of Astronomy, Virginia Institute for Theoretical Astronomy, and The NSF-Simons AI Institute for Cosmic Origins, University of Virginia

Jeff Rich, The Observatories, Carnegie Institution for Science

Z. S. Hemler, Department of Astrophysical Sciences, Princeton University

Qian-Hui Chen, Research School for Astronomy & Astrophysics and ASTRO 3D, Australian National University

Peixin Zhu, Institute for Theory & Computation, Center for Astrophysics | Harvard & Smithsonian and Research School for Astronomy & Astrophysics, Australian National University

Mark Seibert, The Observatories, Carnegie Institution for Science

Lars Hernquist, Institute for Theory & Computation, Center for Astrophysics | Harvard & Smithsonian

Barry Madore, The Observatories, Carnegie Institution for Science

---

Media Contact:

Christine Buckley
Director of Communications
Center for Astrophysics | Harvard & Smithsonian
Tel: 617-599-9628
christine.buckley@cfa.harvard.edu

---

NASA’s Hubble Revisits Crab Nebula to Track 25 Years of Expansion

PR Image heic2607a
Crab Nebula (2024 Hubble image)

PR Image heic2607b
Crab Nebula (new image from 1999/2000 data)

PR Image heic2607c
Crab Nebula (2024 Hubble image, annotated)

PR Image heic2607d
Crab Nebula (new image from 1999/2000 data, annotated)

---

Videos


PR Video heic2607a
The Crab Nebula


PR Video heic2607b
Pan Video: The Crab Nebula (2024 Hubble image)


PR Video heic2607c
Pan Video: The Crab Nebula (new Hubble image from 1999/2000 data)

---

Nearly a millennium ago, astronomers witnessed a brilliant new star blazing in the sky — a supernova so bright it was visible in daylight for weeks. Today, its expanding remnant, the Crab Nebula, continues to evolve 6,500 light-years away. First linked to historical records by Edwin Hubble, the nebula has since been studied in exquisite detail by the NASA/ESA Hubble Space Telescope, which has now revisited this ancient explosion to trace its ongoing expansion and transformation.

A quarter-century after its first observations of the full Crab Nebula, the Hubble Space Telescope has taken a fresh look at the supernova remnant. The Crab Nebula is the aftermath of SN 1054, located 6,500 light-years from Earth in the constellation Taurus.

The result is an unparalleled, detailed look at the aftermath of a supernova and how it has evolved over Hubble’s long lifetime. A paper detailing the new Hubble observation is published in The Astrophysical Journal.

The supernova remnant was discovered in the mid-18th century, and in the 1950s Edwin Hubble was among several astronomers who noted the close correlation between Chinese astronomical records of a supernova and the position of the Crab Nebula. The discovery that the heart of the Crab contained a pulsar — a rapidly rotating neutron star — that was powering the nebula’s expansion finally aligned modern observations and ancient records.

In its new image of the nebula, Hubble has captured extraordinary details of its filamentary structure, as well as the considerable outward movement of those filaments over 25 years, at a pace of 5.5 million kilometres per hour. Hubble is the only telescope with the combination of longevity and resolution capable of capturing these detailed changes.

For better comparison with the new image, Hubble’s 1999 image of the Crab was re-processed. The variation of colors in both of the Hubble images shows a combination of changes in local temperature and density of the gas as well as its chemical omposition.

The science team has noted that the filaments around the periphery of the nebula appear to have moved more compared to those in the centre and that rather than stretching out over time, they appear to have simply moved outward. This is due to the nature of the Crab as a pulsar wind nebula powered by synchrotron radiation, which is created by the interaction between the pulsar’s magnetic field and the nebula’s material. In other well-known supernova remnants, the expansion is instead driven by shockwaves from the initial explosion, eroding surrounding shells of gas that the dying star previously cast off.

The new, higher-resolution Hubble observations are also providing additional insights into the 3D structure of the Crab Nebula, which can be difficult to determine from a 2D image. Shadows of some of the filaments can be seen cast onto the haze of synchrotron radiation in the nebula’s interior. Counterintuitively, some of the brighter filaments in the latest Hubble images show no shadows, indicating they must be located on the far side of the nebula.

According to the science team, the real value of Hubble’s Crab Nebula observations is still to come. The Hubble data can be paired with recent data from other telescopes that are observing the Crab in different wavelengths of light. The NASA/ESA/CSA James Webb Space Telescope released its infrared-light observations of the Crab Nebula in 2024. Comparison of the Hubble image with other contemporary multiwavelength observations will help scientists put together a more complete picture of the supernova’s continuing aftermath, centuries after astronomers first wondered at a new little star twinkling in the sky.

Source: ESA/Hubble/News

---

More information

The Hubble Space Telescope is a project of international cooperation between ESA and NASA.

Image Credit: NASA, ESA, STScI, W. Blair (JHU). Image Processing: J. DePasquale (STScI)

---

Links

• Release on NASA website
• Science paper

---

Contacts

Bethany Downer
ESA/Hubble Chief Science Communications Officer
Email: Bethany.Downer@esahubble.org

---

NASA’s Hubble Detects First-Ever Spin Reversal of Tiny Comet

Comet 41P (Artist's Concept)

This artist’s concept depicts comet 41P, a tiny Jupiter-family comet, as it approached the Sun and frozen gases began to sublimate and shoot material off into space. Credit Illustration: NASA, ESA, CSA, Ralf Crawford STScI).

Comet 41P Reversal Animation

This artist’s concept depicts comet 41P as it approached the Sun and frozen gases began to sublimate off the comet’s surface. This animation only depicts one jet, but this comet may have multiple streams of material ejecting into space. Credit Animation: NASA, ESA, CSA, Ralf Crawford (STScI). Video

---

Astronomers using NASA’s Hubble Space Telescope have found evidence that the spinning of a small comet slowed and then reversed its direction of rotation, offering a dramatic example of how volatile activity can affect the spin and physical evolution of small bodies in the solar system. This is the first time researchers have observed evidence of a comet reversing its spin.

The object, comet 41P/Tuttle-Giacobini-Kresák, or 41P for short, likely originated in the Kuiper Belt, and was flung into its current trajectory by Jupiter’s gravity, now visiting the inner solar system every 5.4 years.

After its 2017 close passage around the Sun, scientists found that comet 41P experienced a dramatic slowdown in its rotation. Data from NASA’s Neil Gehrels Swift Observatory in May 2017 showed the object was spinning three times more slowly than it had in March 2017 when it was observed by the Discovery Channel Telescope at Lowell Observatory in Arizona.

A new analysis of follow-up Hubble observations has shown the spin of this comet took an even more unusual turn.

Hubble images from December 2017 detected the comet spinning much faster again, with a period of approximately 14 hours, compared to the 46 to 60 hours measured by Swift. The simplest explanation, researchers say, is that the comet continued slowing until it almost stopped, and was then forced to spin in the near-opposite direction by outgassing jets on its surface.

The science paper detailing this finding published Thursday in The Astronomical Journal.

Small, temperamental nucleus

Hubble also constrains the size of the comet’s nucleus, measuring it at around 0.6 miles across (about a kilometer), or about three times the height of the Eiffel Tower.

This is especially small for a comet, making it easy to torque, or twist.

As a comet approaches the Sun, heat causes frozen ices to sublimate, venting material into space.

“Jets of gas streaming off the surface can act like small thrusters,” said paper author David Jewitt of the University of California at Los Angeles. “If those jets are unevenly distributed, they can dramatically change how a comet, especially a small one, rotates.”

The comet was originally spinning in one direction, but gas jets pushing against that motion gradually slowed it down. Because the jets kept pushing, they ultimately caused the comet to start rotating in the opposite direction.

“It’s like pushing a merry-go-round,” said Jewitt. “If it’s turning in one direction, and then you push against that, you can slow it and reverse it.”

Evidence of rapid evolution

The study also shows that the comet’s overall activity has declined significantly since earlier returns. During its 2001 perihelion passage, 41P was unusually active for its size. By 2017, its gas production had decreased by roughly an order of magnitude.

This change suggests that the comet’s surface may be evolving quickly, possibly as near-surface volatile materials become depleted or covered by insulating dust layers.

Most changes in comet structure occur over centuries or longer. The rapid rotational shifts observed in comet 41P provide a rare opportunity to witness evolutionary processes unfolding on a human timescale.

Modeling based on the measured torques and mass loss rates suggest that continued rotational changes could eventually lead to structural instability for comet 41P. If a comet spins too rapidly, centrifugal forces can overcome its weak gravity and strength, potentially causing fragmentation or even disintegration.

“I expect this nucleus will very quickly self-destruct,” said Jewitt.

Yet, comet 41P has likely occupied its present orbit for roughly 1,500 years.

Archival find

Hubble has been collecting imaging and spectroscopic data from across the cosmos for over 35 years, and all of those observations are available in the Mikulski Archive for Space Telescopes, a central repository for data from more than a dozen astronomical missions, including Hubble.

Jewitt found these observations while browsing the archive, and realized they were yet-to-be analyzed.

By making NASA’s science data open to all, observations made years, or even decades ago, can be revisited to answer new scientific questions. In many cases, scientists continue to make discoveries not just with new observations, but by mining the archive built over decades of space exploration.

The Hubble Space Telescope has been operating for over three decades and continues to make ground-breaking discoveries that shape our fundamental understanding of the universe. Hubble is a project of international cooperation between NASA and ESA (European Space Agency). NASA’s Goddard Space Flight ;Center in Greenbelt, Maryland, manages the telescope and mission operations. Lockheed Martin Space, based in Denver, also supports mission operations at Goddard. The Space Telescope Science Institute in Baltimore, which is operated by the Association of Universities for Research in Astronomy, conducts Hubble science operations for NASA.

Source: NASA's Hubble Space Telescope/News

Facebook: @NASAHubble - X (Twitter): @NASAHubble - Instagram: @NASAHubble

---

Details:

Last Updated: Mar 26, 2026
Editor: Andrea Gianopoulos
Location: NASA Goddard Space Flight Center

Contact Media:

Claire Andreoli
NASA’s Goddard Space Flight Center
Greenbelt, Maryland
claire.andreoli@nasa.gov

Hannah Braun, Ann Jenkins
Space Telescope Science Institute
Baltimore, Maryland

---

NASA Webb, Hubble Share Most Comprehensive View of Saturn to Date

Saturn (Webb NIRCam and Hubble WFC3/UVIS)

Complementary views of Saturn from NASA’s James Webb Space Telescope and Hubble Space Telescope show a dynamic planet with atmospheric features, orbiting moons, and bright rings. Credit Image: NASA, ESA, CSA, STScI, Amy Simon (NASA-GSFC), Michael Wong (UC Berkeley); Image Processing: Joseph DePasquale (STScI)

Saturn (Webb NIRCam Image)

Captured Nov. 29, 2024 by NASA’s James Webb Space Telescope, this infrared view of Saturn shows its glowing icy rings and layered atmosphere. Several moons are visible, including Janus, Dione, and Enceladus. Credit Image: NASA, ESA, CSA, STScI, Amy Simon (NASA-GSFC), Michael Wong (UC Berkeley); Image Processing: Joseph DePasquale (STScI)

Saturn (WFC3/UVIS)

Captured Aug. 22, 2024 by NASA’s Hubble Space Telescope, this visible-light view of Saturn reveals the planet’s softly banded atmosphere and iconic rings. Several moons are also visible, labeled Janus, Mimas, and Epimetheus. Credit Image: NASA, ESA, CSA, STScI; Image Processing: Joseph DePasquale (STScI)

Saturn (Webb NIRCam Wide Image)

A wider view of Saturn from NASA’s James Webb Space Telescope shows six of Saturn’s larger moons, including the largest, Titan, at far left. Credit Image: NASA, ESA, STScI, Amy Simon (NASA-GSFC), Michael Wong (UC Berkeley); Image Processing: Joseph DePasquale (STScI)

Saturn (Webb NIRCam and Hubble WFC3/UVIS Compass Image)

These images of Saturn, captured by NASA’s James Webb and Hubble Spaces Telescopes, shows compass arrows, scale bar, and color key for reference. Credit Image: NASA, ESA, CSA, STScI; Image Processing: Joseph DePasquale (STScI)

---

NASA’s James Webb Space Telescope and Hubble Space Telescope have teamed up to capture new views of Saturn, revealing the planet in strikingly different ways. Observing in complementary wavelengths of light, the two space observatories provide scientists with a richer, more layered understanding of the gas giant’s atmosphere.

Both sense sunlight reflected from Saturn’s banded clouds and hazes, but where Hubble reveals subtle color variations across the planet, Webb’s infrared view senses clouds and chemicals at many different depths in the atmosphere, from the deep clouds to the tenuous upper atmosphere.

Together, scientists can effectively ‘slice’ through Saturn’s atmosphere at multiple altitudes, like peeling back the layers of an onion. Each telescope tells a different part of Saturn’s story, and the observations together help researchers understand how Saturn’s atmosphere works as a connected three-dimensional system. Both complement previous observations done by NASA’s Cassini orbiter during its time studying the Saturnian system from 1997 to 2017.

The Hubble image seen here was captured as part of a more than a decade long monitoring program called OPAL (Outer Planet Atmospheres Legacy) in August 2024, while the Webb image was captured a few months later using Director’s Discretionary Time.

The newly released images highlight features from Saturn’s busy atmosphere.

In the Webb image, a long-lived jet stream known as the “ribbon wave” meanders across the northern mid-latitudes, influenced by otherwise undetectable atmospheric waves. Just below that, a small spot represents a lingering remnant from the “Great Springtime Storm” of 2010 to 2012. Several other storms dotting the southern hemisphere of Saturn are visible in Webb’s image, as well.

All these features are shaped by powerful winds and waves beneath the visible cloud deck, making Saturn a natural laboratory for studying fluid dynamics under extreme conditions.

Several of the pointed edges of Saturn’s iconic hexagon-shaped jet stream at its north pole, discovered by NASA’s Voyager spacecraft in 1981, are also faintly visible in both images. It remains one of the solar system’s most intriguing weather patterns. Its persistence over decades highlights the stability of certain large-scale atmospheric processes on giant planets. These are likely the last high-resolution looks we’ll see of the famous hexagon until the 2040’s, as the northern pole enters winter and will shift into darkness for 15 years.

In Webb’s infrared observations, Saturn’s poles appear distinctly grey-green, indicating light emitting at wavelengths around 4.3 microns. This distinct feature could come from a layer of high-altitude aerosols in Saturn’s atmosphere that scatters light differently at those latitudes. Another possible explanation is auroral activity, as charged molecules interacting with the planet’s magnetic field can produce glowing emissions near the poles.

NASA’s Hubble and Webb have already explored Saturn’s auroras, provided insights into Jupiter’s spectacular auroras also seen with Hubble, confirmed the auroras of Uranus glimpsed in 2011 by Hubble, and detected Neptune’s auroras for the first time with Webb.

In Webb’s infrared image, the rings are extremely bright because they are made of highly reflective water ice. In both images, we’re seeing the sunlit face of the rings, a little less so in the Hubble image, hence the shadows visible underneath on the planet.

There are also subtle ring features such as spokes and structure in the B ring (the thick central region of the rings) that appear differently between the two observatories. The F ring, the outermost ring, looks thin and crisp in the Webb image, while it only slightly glows in the Hubble image..

Saturn’s orbit around the Sun, combined with the position of Earth in its annual orbit, determines our changing viewing angle of Saturn’s face and ring.

These 2024 observations, taken 14 weeks apart, show the planet moving from northern summer toward the 2025 equinox. As Saturn transitions into southern spring, and later southern summer in the 2030’s, Hubble and Webb will have progressively better views of that hemisphere.

Hubble’s observations of Saturn for decades have built a record of its evolving atmosphere. Programs like OPAL, with its annual monitoring, are allowing scientists to track storms, banding patterns, and seasonal shifts over time. Webb now adds powerful infrared capabilities to this ongoing record, extending what researchers can measure about Saturn’s atmospheric structure and dynamic processes.

The James Webb Space Telescope is the world’s premier space science observatory. Webb is solving mysteries in our solar system, looking beyond to distant worlds around other stars, and probing the mysterious structures and origins of our universe and our place in it. Webb is an international program led by NASA with its partners, ESA (European Space Agency) and CSA (Canadian Space Agency).

Source: NASA's James Webb Space Telescope/Latest News

---

Details:

Last Updated: Mar 26, 2026
Location: NASA Goddard Space Flight Center

Contact Media:

Laura Betz
NASA’s Goddard Space Flight Center
Greenbelt, Maryland
laura.e.betz@nasa.gov

Hannah Braun
Space Telescope Science Institute
Baltimore, Maryland

Christine Pulliam
Space Telescope Science Institute
Baltimore, Maryland

---

A Solar System in the making? Two planets spotted forming in disc around young star

PR Image eso2604a
VLT images of two planets forming around the young star WISPIT 2

PR Image eso2604b
Composite VLT image of two planets around the WISPIT 2 star

PR Image eso2604c
Spectrum of the baby exoplanet WISPIT 2c

PR Image eso2604d
Wide-field view of the area around the WISPIT 2 star

PR Image eso2604e
The young star WISPIT 2 in the constellation Aquila

---

Videos


PR Video eso2604a
Two planets spotted forming around a young star | ESO News


PR Video eso2604b
Zooming into the young planetary system around the WISPIT 2 star

---

Astronomers have observed two planets forming in the disc around a young star named WISPIT 2. Having previously detected one planet, the team have now employed European Southern Observatory (ESO) telescopes to confirm the presence of another. These observations, and the unique structure of the disc around the star, indicate that the WISPIT 2 system could resemble a young Solar System.

“WISPIT 2 is the best look into our own past that we have to date,” says Chloe Lawlor, PhD student at the University of Galway, Ireland, and lead author of the study published today in The Astrophysical Journal Letters.

The system is only the second known, after PDS 70, where two planets have been directly observed in the process of forming around their host star. Unlike PDS 70, however, WISPIT 2 has a very extended planet-forming disc with distinctive gaps and rings. "These structures suggest that more planets are currently forming, which we will eventually detect,” Lawlor says.

"WISPIT 2 gives us a critical laboratory not just to observe the formation of a single planet but an entire planetary system," says Christian Ginski, study co-author and researcher at the University of Galway. With such observations, astronomers aim to better understand how baby planetary systems develop into mature ones, like our own.

The first newborn planet found in the system — named WISPIT 2b — was detected last year, with a mass almost five times that of Jupiter and orbiting the central star at around 60 times the distance between Earth and the Sun. “This detection of a new world in formation really showed the amazing potential of our current instrumentation,” said Richelle van Capelleveen, PhD student at Leiden Observatory, the Netherlands, and leader of the previous study. After an additional object was identified near the star [1], measurements made with ESO’s Very Large Telescope (VLT) and the VLT Interferometer (VLTI) confirmed its planetary nature. The new planet — WISPIT 2c — is four times closer to the central star and is twice as massive as WISPIT 2b. Both planets are gas giants, like the outer planets in our Solar System.

To confirm the existence of WISPIT 2c the team employed the SPHERE instrument on ESO's VLT, which captured an image of the object. The team then used the GRAVITY+ instrument on the VLTI to confirm that the object was indeed a planet. "Critically our study made use of the recent upgrade to GRAVITY+ without which we would not have been able to get such a clear detection of the planet so close to its star," says Guillaume Bourdarot, study co-author and researcher at the Max Planck Institute for Extraterrestrial Physics, Garching, Germany.

Both planets in WISPIT 2 appear in clear gaps within the disc of dust and gas circling the young star. These gaps result from each planet's development: particles in the disc accumulate, their gravity pulling in more material until an embryo planet forms. The remaining material, around each gap, creates distinctive dust rings in the disc.

Besides the gaps that the two planets were found in, there is at least one smaller gap farther out in the WISPIT 2 disc. "We suspect there may be a third planet carving out this gap" says Lawlor, "potentially of Saturn mass owing to the gap’s being much narrower and shallower". The team are eager to make follow-up observations, with Ginski noting that “with ESO’s upcoming Extremely Large Telescope, we may be able to directly image such a planet.”

Source: ESO/News

---

Notes

[1] The first hints of the presence of a second planet came from observations made with the University of Arizona's MagAO-X on the 6.5-metre Magellan Telescopes in Chile and the University of Virginia's LMIRcam on the Large Binocular Telescope Interferometer in the USA.

---

More information

This research was presented in a paper to appear in The Astrophysical Journal Letters (https://doi.org/10.3847/2041-8213/ae4b3b).

The team is composed of C. Lawlor (School of Natural Sciences, Centre for Astronomy and Ryan Institute, University of Galway, Ireland [Galway]), R. F. van Capelleveen (Leiden Observatory, Leiden University,The Netherlands [Leiden]), G. Bourdarot (Max Planck Institute for Extraterrestrial Physics, Garching, Germany [MPE]), C. Ginski (Galway and Center for Astronomical Adaptive Optics, Department of Astronomy, University of Arizona, Tucson, USA [CAAO]), M. A. Kenworthy (Leiden), T. Stolker (Leiden), L. Close (CAAO), A. J. Bohn (Leiden), F. Eisenhauer (MPE and Department of Physics, Technical University of Munich, Garching, Germany), P. Garcia (Faculdade de Engenharia, Universidade do Porto, Portugal and CENTRA – Centro de Astrofísica e Gravitação, IST, Universidade de Lisboa, Portugal), S. F. Honig (School of Physics and Astronomy, University of Southampton, United Kingdom), J. Kammerer (European Southern Observatory, Garching Germany), L. Kreidberg (Max Planck Institute for Astronomy, Heidelberg, Germany), S. Lacour (LIRA, Observatoire de Paris, Université PSL, CNRS, Sorbonne Université, Université de Paris, Meudon, France), J.-B. Le Bouquin (Univ. Grenoble Alpes, CNRS, IPAG, Grenoble, France), E. Mamajek (Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA), M. Nowak (LIRA), T. Paumard (LIRA), C. Straubmeier (1st Institute of Physics, University of Cologne, Germany), N. van der Marel (Leiden) and the exoGRAVITY Collaboration.

The European Southern Observatory (ESO) enables scientists worldwide to discover the secrets of the Universe for the benefit of all. We design, build and operate world-class observatories on the ground — which astronomers use to tackle exciting questions and spread the fascination of astronomy — and promote international collaboration for astronomy. Established as an intergovernmental organisation in 1962, today ESO is supported by 16 Member States (Austria, Belgium, Czechia, Denmark, France, Finland, Germany, Ireland, Italy, the Netherlands, Poland, Portugal, Spain, Sweden, Switzerland and the United Kingdom), along with the host state of Chile and with Australia as a Strategic Partner. ESO’s headquarters and its visitor centre and planetarium, the ESO Supernova, are located close to Munich in Germany, while the Chilean Atacama Desert, a marvellous place with unique conditions to observe the sky, hosts our telescopes. ESO operates three observing sites: La Silla, Paranal and Chajnantor. At Paranal, ESO operates the Very Large Telescope and its Very Large Telescope Interferometer, as well as survey telescopes such as VISTA. Also at Paranal, ESO will host and operate the south array of the Cherenkov Telescope Array Observatory, the world’s largest and most sensitive gamma-ray observatory. Together with international partners, ESO operates ALMA on Chajnantor, a facility that observes the skies in the millimetre and submillimetre range. At Cerro Armazones, near Paranal, we are building “the world’s biggest eye on the sky” — ESO’s Extremely Large Telescope. From our offices in Santiago,Chile we support our operations in the country and engage with Chilean partners and society.

---

Links

• Research paper
• Photos of the VLT/I
• Find out more about ESO's Extremely Large Telescope on our dedicated website and press kit
• For journalists: subscribe to receive our releases under embargo in your language 
• For scientists: got a story? Pitch your research

---

Contacts:

Chloe Lawlor
University of Galway
Galway, Ireland
Email: c.lawlor13@universityofgalway.ie

Christian Ginski
University of Galway
Galway, Ireland
Email: christian.ginski@universityofgalway.ie

Richelle van Capelleveen
Leiden Observatory, Leiden University
Leiden, the Netherlands
Email: capelleveen@strw.leidenuniv.nl

Guillaume Bourdarot
Max Planck Institute for Extraterrestrial Physics
Garching, Germany
Tel: +498930000-3295
Email: bourdarot@mpe.mpg.de

Bárbara Ferreira
ESO Media Manager
Garching bei München, Germany
Tel: +49 89 3200 6670
Cell: +49 151 241 664 00
Email: press@eso.org

---

A chemically rich outflow from a young Sun-like star: A new laboratory for shock chemistry

During the early stages of star formation, material is ejected at high speed from near the forming star forming a bipolar structure referred to as protostellar outflow. Credit: NASA, ESA, CSA, STScI

---

A study led by the Center for Astrochemical Studies (CAS) at MPE has revealed an unexpectedly rich chemical inventory in the outflow of the young, Sun-like protostar IRAS 4B1, located about 300 parsecs away in the star-forming region NGC 1333 in the Perseus molecular cloud. So far, there is only one low-mass protostellar outflow in which emission of complex organic molecules has been studied extensively, making IRAS 4B1 a rare and valuable laboratory for exploring how these molecules behave under extreme conditions.

One of the central questions in astrochemistry is how simple interstellar molecules grow into more complex species during the process of star and planet formation. As these processes unfold over millions of years, astronomers rely on snapshots of many systems at different evolutionary stages, using comparisons with theoretical models to trace the chemical evolution.

Protostellar outflows offer a unique window into these transformations. In the earliest stages of star formation, material is ejected from the young forming star at high speed. When this gas collides with the surrounding cloud, it generates shock waves that compress and briefly heat the gas and dust, rapidly altering the chemistry. These shocks can release complex organic molecules - defined as carbon-bearing species containing at least six atoms - that were previously frozen onto dust grains, injecting a burst of rich chemistry into the surrounding region.

Despite their importance, such detections are rare. “While working on a separate PRODIGE project mapping methyl cyanide (CH₃CN) toward IRAS 4B1, I noticed emission that appeared to trace the outflow rather than the hot surroundings of the forming star,” says Laura Busch, a postdoctoral researcher at MPE who led the study. “This made me search the data for more complex molecules – and I found them.”

The PRODIGE observations, carried out with the Northern Extended Millimeter Array (NOEMA), reveal a surprisingly diverse chemical composition in the outflow. “The combination of high sensitivity and broad spectral coverage makes PRODIGE ideally suited to this kind of study,” adds Jaime Pineda, scientist at MPE. “It allows us to detect and map multiple complex molecules simultaneously — something that would otherwise be extremely difficult.”

Maps of molecular emission show that different molecules trace distinct regions within the outflow, indicating variations in temperature and density. Some species are brightest where temperatures are highest, while others originate in cooler zones, reflecting different chemical pathways. These findings provide fresh insight into how complex organic molecules — the precursors of prebiotic chemistry — are processed by shocks during the earliest phases of star formation.

Source: Max Planck Institute for Extraterrestrial Physics (MPE)/Paper of the Month

---

The PROtostars & DIsks: Global Evolution (PRODIGE; PIs: P. Caselli and Th. Henning) is a collaboration between the Max Planck Society and the Institut de Radioastromie Millimétrique (IRAM) located in France. The project targeted a total of 30 Class 0/I protostellar systems in the Perseus molecular cloud, with the main goal of studying the kinematics of star formation. The observations cover a broad spectral bandwidth of 16GHz, a unique treat of the NOrthern Extended Millimeter Array (NOEMA) located in the French Alpes and run by IRAM that was used to observe the data, is essential for identifying molecules and study their emission spectra.

---

Contacts:

Dr. Laura Busch
Post-Doc
lbusch@mpe.mpg.de
Max Planck Institute for Extraterrestrial Physics, Garching
Center for Astrochemical Studies

Dr. Jaime Pineda Fornerod
Scientist
Tel: +49 (0)89 30000-3610
Fax: +49 (0)89 30000-3950
jpineda@mpe.mpg.de
Max Planck Institute for Extraterrestrial Physics, Garching
Center for Astrochemical Studies

---

Publication

L. A. Busch, J. E. Pineda, P. Caselli, D. M. Segura-Cox, S. Narayanan, C. Gieser, M. J. Maureira, T.-H. Hsieh, Y. Lin, M. T. Valdivia-Mena, L. Bouscasse, Th. Henning, D. Semenov, A. Fuente, Y.-R. Chou, L. Mason, P. C. Cortés, L. W. Looney, I. W. Stephens, M. Tafalla, A. Dutrey, W. Kwon, P. Saha

PRODIGE - envelope to disk with NOEMA: VII. (Complex) organic molecules in the NGC1333 IRAS4B1 outflow: A new laboratory for shock chemistry

arXiv

Source | DOI

---

Smithsonian Astrophysical Observatory Receives $3.2M to Transform X-ray Astronomy for the Next Generation

The Lynx X-ray Observatory, which will adapt advanced manufacturing techniques developed in other industries and apply them to X-ray astronomy. Credit: G. Tremblay, CfA. High Resolution Image

The Lynx X-ray Observatory, which will adapt advanced manufacturing techniques developed in other industries and apply them to X-ray astronomy. High Resolution Image

---

The grant from the Gordon and Betty Moore Foundation will advance technology for the new Lynx X-ray Observatory, allowing astronomers to study the universe’s first supermassive black holes with better resolution than ever before.

Cambridge, MA (March Date, 2026) — The Gordon and Betty Moore Foundation has awarded the Smithsonian Astrophysical Observatory (SAO) $3.2 million to advance the key mirror technology for the new Lynx X-ray Observatory. Once launched, Lynx will dramatically improve sensitivity and imaging performance for X-ray astronomy.

The Moore Foundation grant will enable SAO, a part of the Center for Astrophysics | Harvard & Smithsonian (CfA), to expand technical work on an X-ray mirror system that increases the imaging capabilities of X-ray astronomy with 16x the field of view, up to 20x the spectral resolution, and 800x the surveying speed of current observatories.

“We need X-rays to confirm the identity of the earliest black holes forming,” said Randall Smith, associate director for science at the CfA, and lead PI on the project.

“Lynx is a transformational X-ray observatory that is designed to detect the first black holes and understand how they formed alongside the first galaxies.”

One of Lynx’s primary scientific goals is to observe the dawn of black holes, or the first black holes that formed in the early universe. Recent discoveries from NASA’s James Webb Space Telescope have revealed candidate early galaxies and compact objects, but X-ray observations are required to determine whether these sources contain actively forming black holes.

“We need X-rays to confirm the identity of the earliest black holes forming,” said Randall Smith, associate director for science at the CfA, and lead PI on the project. “Right now, our candidate sources are very bright in X-ray, but not for very long, and we need increased speed and resolution to observe and understand them. Lynx is a transformational X-ray observatory that is designed to detect the first black holes and understand how they formed alongside the first galaxies.”

The new mirrors enabled by the grant use modern fabrication methods, including ion beam forming, which shapes materials at the molecular level, to achieve the precision needed for next-generation X-ray astronomy.

“Technology from astronomy often is transferred out to other industries. For Lynx, we’re adapting advanced manufacturing techniques developed in other industries and applying them to X-ray astronomy,” said Peter Cheimets, telescope developer at the CfA, and an engineer for Lynx.

“This is not a spin-off of space technology, it’s a spin-in. By bringing these proven methods into astrophysics, and using them all at the same time, we can build mirrors with the precision, performance, speed, and cost needed to make Lynx possible.”

To date, the Moore Foundation has provided more than $28 million in support for black hole research and the launch of new projects at the CfA. With the new grant, Lynx joins the list of CfA-led black hole projects to be funded by Moore Foundation.

“CfA is leading the way in next-generation X-ray astronomy,” said Lisa Kewley, director of the CfA. “The support we’ve received, and continue to receive, from the Gordon and Betty Moore Foundation is crucial to supporting the cutting-edge observatories that will allow us to gain a deeper and clearer understanding of the universe for years to come.”

Source: Harvard-Smithsonian Center for Astrophysics (CfA)/News

---

About the Center for Astrophysics | Harvard & Smithsonian/News

The Center for Astrophysics | Harvard & Smithsonian is a collaboration between Harvard and the Smithsonian designed to ask—and ultimately answer—humanity's greatest unresolved questions about the nature of the universe. The Center for Astrophysics is headquartered in Cambridge, MA, with research facilities across the U.S. and around the world.

---

About the Gordon and Betty Moore Foundation

The Gordon and Betty Moore Foundation advances scientific discovery, environmental conservation, and the special character of the San Francisco Bay Area. Visit moore.org and follow @MooreFound.

---

Media Contact:

Christine Buckley
Director of Communications
Center for Astrophysics | Harvard & Smithsonian
Tel: 617-599-9628
christine.buckley@cfa.harvard.edu

---

NASA’s Hubble Unexpectedly Catches Comet Breaking Up

This series of images from NASA’s Hubble Space Telescope of the fragmenting comet C/2025 K1 (ATLAS) was taken over the course of three consecutive days: Nov. 8, 9, and 10, 2025. This is the first time Hubble has witnessed a comet so early in the process of breaking up. - Comet C/2025 K1 Compass Image - Credit: Image: NASA, ESA, Dennis Bodewits (AU); Image Processing: Joseph DePasquale (STScI)

This diagram shows the path Comet C/2025 K1 (ATLAS), or K1, took as it swung past the Sun and began its journey out of the solar system. NASA’s Hubble Space Telescope captured the inset image of the fragmenting comet just a month after K1’s closest approach to the Sun. Credit: Illustration: NASA, ESA, Ralf Crawford (STScI)

Hubble Accidentally Catches Comet Breaking Up

Fragmenting Comet C/2025 K1 - Videos

---

In a happy twist of fate, NASA’s Hubble Space Telescope just witnessed a comet in the act of breaking apart. The chance of that happening while Hubble watched is extraordinarily minuscule. The findings published Wednesday in the journal Icarus.

The comet K1, whose full name is C/2025 K1 (ATLAS)—not to be confused with interstellar comet 3I/ATLAS—was not the original target of the Hubble study.

“Sometimes the best science happens by accident,” said co-investigator John Noonan, a research professor in the Department of Physics at Auburn University in Alabama. “This comet got observed because our original comet was not viewable due to some new technical constraints after we won our proposal. We had to find a new target—and right when we observed it, it happened to break apart, which is the slimmest of slim chances.”

Noonan didn’t know K1 was fragmenting until he viewed the images the day after Hubble took them. “While I was taking an initial look at the data, I saw that there were four comets in those images when we only proposed to look at one,” said Noonan. “So we knew this was something really, really special.”

This is an experiment the researchers always wanted to do with Hubble. They had proposed many Hubble observations to catch a comet breaking up. Unfortunately, these are very difficult to schedule, and they were never successful.

“The irony is now we're just studying a regular comet and it crumbles in front of our eyes,” said principal investigator Dennis Bodewits, also a professor in Auburn University’s Department of Physics.

“Comets are leftovers of the era of solar system formation, so they’re made of ‘old stuff’—the primordial materials that made our solar system,” said Bodewits. “But they are not pristine—they've been heated; they've been irradiated by the Sun and by cosmic rays. So, when looking at a comet’s composition, the question we always have is, ‘Is this a primitive property or is this due to evolution?’ By cracking open a comet, you can see the ancient material that has not been processed.”

Hubble caught K1 fragmenting into at least four pieces, each with a distinct coma, the fuzzy envelope of gas and dust that surrounds a comet’s icy nucleus. Hubble cleanly resolved the fragments, but to ground-based telescopes, at the time they only appeared as barely distinguishable, bright blobs.

Hubble’s images were taken just a month after K1’s closest approach to the Sun, called perihelion. The comet’s perihelion was inside Mercury’s orbit, about one-third the distance of the Earth from the Sun. During perihelion, a comet experiences its most intense heating and maximum stress. Just past perihelion is when some long-period comets like K1 tend to fall apart.

Before it fragmented, K1 was likely a bit larger than an average comet, probably around 5 miles across. The team estimates the comet began to disintegrate eight days before Hubble viewed it. Hubble took three 20-second images, one on each day from Nov. 8 through Nov. 10, 2025. As it watched the comet, one of K1’s smaller pieces also broke up.

Because Hubble’s sharp vision can distinguish extremely fine details, the team could trace the history of the fragments back to when they were one piece. That allowed them to reconstruct the timeline. But in doing so, they uncovered a mystery: Why was there a delay between when the comet broke up and when bright outbursts were seen from the ground? When the comet fragmented and exposed fresh ice, why didn’t it brighten almost instantaneously?

The team has some theories. Most of a comet’s brightness is sunlight reflected off of dust grains. But when a comet cracks open, it reveals pure ice. Maybe a layer of dry dust needs to form over the pure ice and then blow off. Or maybe heat needs to get below the surface, build up pressure, and then eject an expanding shell of dust.

“Never before has Hubble caught a fragmenting comet this close to when it actually fell apart. Most of the time, it's a few weeks to a month later. And in this case, we were able to see it just days after,” said Noonan. “This is telling us something very important about the physics of what's happening at the comet’s surface. We may be seeing the timescale it takes to form a substantial dust layer that can then be ejected by the gas.”

The research team is looking forward to finishing the analysis of the gases to come from the comet. Already, ground-based analysis shows that K1 is chemically very strange—it is significantly depleted in carbon, compared with other comets. Spectroscopic analysis from Hubble’s STIS (Space Telescope Imaging Spectrograph) and COS (Cosmic Origins Spectrograph) instruments is likely to reveal much more about the composition of K1 and the very origins of our solar system, as NASA’s space telescopes continue to contribute to our understanding of planetary science.

The comet K1 is now a collection of fragments about 250 million miles from Earth. Located in the constellation Pisces, it is heading out of the solar system, not likely to ever return.

The Hubble Space Telescope has been operating for over three decades and continues to make ground-breaking discoveries that shape our fundamental understanding of the universe. Hubble is a project of international cooperation between NASA and ESA (European Space Agency). NASA’s Goddard Space Flight Center in Greenbelt, Maryland, manages the telescope and mission operations. Lockheed Martin Space, based in Denver, also supports mission operations at Goddard. The Space Telescope Science Institute in Baltimore, which is operated by the Association of Universities for Research in Astronomy, conducts Hubble science operations for NASA.

Source: NASA's Hubble Space Telescope/News

---

Extremely Rare Second-Generation Star Discovered Inside Ancient Relic Dwarf Galaxy

PR Image noirlab2607a
Pictor II ultra-faint dwarf galaxy

PR Image noirlab2607b
Star PicII-503 in Pictor II ultra-faint dwarf galaxy

PR Image noirlab2607c
Star PicII-503 in Pictor II ultra-faint dwarf galaxy

PR Image noirlab2607d
Galactic Center Illuminates Cerro Tololo’s Blanco 4-Meter Telescope

PR Image noirlab2607e
Víctor M. Blanco 4-meter Telescope with DECam

PR Image noirlab2607f
Pictor (Annotated)

PR Image noirlab2607g
Pictor

---

The star is the first unambiguous example of chemical enrichment by the first stars in the Universe within a primordial environment

Discovered in the Pictor II dwarf galaxy, star PicII-503 has an extreme deficiency in iron — less than 1/40,000th of the Sun. This signature makes it the clearest example of a star within a primordial system that preserves the chemical enrichment of the Universe’s first stars. PicII-503 also has an extreme overabundance of carbon, providing the missing link to connect carbon-enhanced stars observed in the Milky Way halo to an origin in ancient dwarf galaxies.

Astronomers have discovered one of the most chemically primitive stars ever identified — an ancient stellar relic that preserves the chemical imprint of the very first stars in the Universe. This star, named PicII-503, resides in the tiny, ultra-faint dwarf galaxy Pictor II. The discovery was enabled by the U.S. Department of Energy-fabricated Dark Energy Camera (DECam), mounted on the U.S. National Science Foundation Víctor M. Blanco 4-meter Telescope, at NSF Cerro Tololo Inter-American Observatory (CTIO) in Chile, a Program of NSF NOIRLab.

Pictor II is located in the constellation Pictor. It contains several thousand stars and is more than ten billion years old. PicII-503 lies on the outskirts of the galaxy, and it contains less iron than any other star ever measured outside of the Milky Way, while also having an extreme overabundance of carbon. These signatures unmistakably match those of carbon-enhanced stars found in the outer reaches of the Milky Way, whose origins have, until now, been a mystery.

The study was led by Anirudh Chiti, Brinson Prize Fellow at Stanford University, and the results are presented in a paper appearing in Nature Astronomy.

The first stars in the Universe formed from gas that contained only the simple elements, hydrogen and helium. Within their fiery cores, this first generation of stars created the first elements heavier than helium, such as carbon and iron, which astronomers refer to as “metals.” When these stars exploded, they released their heavy elements into the interstellar medium to be recycled into the next generation of stars.

Second-generation stars are like time capsules, preserving the low amounts of heavy elements released during the explosive deaths of first-generation stars. By searching for these rare, low-metallicity stars and deriving their chemistry, scientists can better understand the mechanisms of initial element production in the Universe.

PicII-503 is the first unambiguous example of a second-generation star in an ultra-faint dwarf galaxy. It was uncovered in data from the DECam MAGIC (Mapping the Ancient Galaxy in CaHK) survey, a 54-night observing program designed to identify the oldest and most chemically primitive stars in the Milky Way and its dwarf galaxy companions. Using a specialized narrow-band filter sensitive to calcium absorption features, astronomers were able to estimate the metal content of thousands of stars from imaging data alone.

Among the hundreds of stars near Pictor II, MAGIC data singled out PicII-503 as an exceptionally metal-poor candidate, allowing researchers to target it for detailed follow-up study. “Without data from MAGIC, it would have been impossible to isolate this star among the hundreds of other stars in the vicinity of the Pictor II ultra-faint dwarf galaxy,” says Chiti.

By combining data from MAGIC, the Magellan/Baade Telescope, and ESO’s Very Large Telescope, the team found that PicII-503 has the lowest iron and calcium abundances ever measured outside of the Milky Way. This paucity of iron and calcium makes it the first object that clearly preserves enrichment from the first stars in a relic dwarf galaxy.

“Discovering a star that unambiguously preserves the heavy metals from the first stars was at the edge of what we thought possible, given the extreme rarity of these objects,” says Chiti. “With the lowest iron abundance ever derived in any ultra-faint dwarf galaxy, PicII-503 provides a window into initial element production within a primordial system that is unprecedented.”

Even more remarkably, the team discovered that PicII-503 has a carbon-to-iron ratio that is over 1500 times that of the Sun. This overabundance matches the distinct carbon signature of low-iron stars long observed in the Milky Way halo. These are known as carbon-enhanced metal-poor stars, and their origin has remained unknown until now.

One hypothesis is that carbon-enhanced metal-poor stars are second-generation stars that preserve the chemical elements produced by low-energy supernovae of first-generation stars. During this process, heavy elements that form close to the star’s interior, like iron, fall back into the remnant compact object, while lighter elements that are near the star’s outer regions, like carbon, are ejected into the interstellar medium to seed the formation of the next generation of stars.

PicII-503 supports the low-energy supernovae explanation because it is found in one of the smallest dwarf galaxies that we know of. If the supernova that produced the metals found in PicII-503 was high-energy, then the elements would have escaped the gravitational pull of the small Pictor II dwarf galaxy. PicII-503 also demonstrates that the carbon-enhanced metal-poor stars observed in the Milky Way halo likely originated from ancient relic dwarf galaxies that have, over time, merged with ours.

“What excites me the most is that we have observed an outcome of the very initial element production in a primordial galaxy, which is a fundamental observation!” says Chiti. “It also cleanly connects to the signature that we have seen in the lowest-metallicity Milky Way halo stars, tying together their origins and the first-star-enriched nature of these objects.”

“Discoveries like this are cosmic archaeology, uncovering rare stellar fossils that preserve the fingerprints of the Universe’s first stars,” says Chris Davis, NSF Program Director for NOIRLab. “We look forward to many more discoveries with the start of the NSF–DOE Rubin Observatory’s Legacy Survey of Space and Time later this year.”

PicII-503 offers a rare, direct glimpse into the Universe’s first chapter of chemical evolution, which is a foundational moment that ultimately set the stage for planets, chemistry, and life itself. It also connects long-standing mysteries about ancient stars in the Milky Way to their origins in primordial dwarf galaxies.

Source: NSF’s National Optical-Infrared Astronomy Research Laboratory (NOIRLab)/News

---

More information

This research was presented in a paper titled “Enrichment by the first stars in a relic dwarf galaxy” appearing in Nature Astronomy. DOI: 10.1038/s41550-026-02802-z

The team is composed of A. Chiti (Stanford University/University of Chicago/Brinson Prize Fellow, USA) , V. M. Placco (NSF NOIRLab, USA), A. B. Pace (University of Virginia, USA), A. P. Ji (University of Chicago/NSF-Simons AI Institute for the Sky, USA), D. S. Prabhu (University of Arizona, USA), W. Cerny (Yale University, USA), G. Limberg (University of Chicago, USA), G. S. Stringfellow (Yale University, USA), A. Drlica-Wagner (Fermi National Accelerator Laboratory/Stanford University/University of Chicago/NSF-Simons AI Institute for the Sky, USA), K. R. Atzberger (University of Virginia, USA), Y. Choi (NSF NOIRLab, USA), D. Crnojević (University of Tampa, USA), P. S. Ferguson (University of Washington, USA), N. Kallivayalil (University of Virginia, USA), N. E. D. Noël (University of Surrey, UK), A. H. Riley (Durham University, UK/Lund University, Sweden), D. J. Sand (University of Arizona, USA), J. D. Simon (Observatories of the Carnegie Institution for Science, USA), A. R. Walker (Cerro Tololo Inter-American Observatory/NSF NOIRLab, Chile), C. R. Bom (Centro Brasileiro de Pesquisas Físicas, Brazil), J. A. Carballo-Bello (Universidad de Tarapacá, Chile), D. J. James (ASTRAVEO LLC, Applied Materials Inc., USA), C. E. Martínez-Vázquez (NSF NOIRLab, USA), G. E. Medina (University of Toronto, Canada), K. Vivas (NSF NOIRLab, Chile).

NSF NOIRLab, the U.S. National Science Foundation center for ground-based optical-infrared astronomy, operates the International Gemini Observatory (a facility of NSF, NRC–Canada, ANID–Chile, MCTIC–Brazil, MINCyT–Argentina, and KASI–Republic of Korea), NSF Kitt Peak National Observatory (KPNO), NSF Cerro Tololo Inter-American Observatory (CTIO), the Community Science and Data Center (CSDC), and NSF–DOE Vera C. Rubin Observatory (in cooperation with DOE’s SLAC National Accelerator Laboratory). It is managed by the Association of Universities for Research in Astronomy (AURA) under a cooperative agreement with NSF and is headquartered in Tucson, Arizona.

The scientific community is honored to have the opportunity to conduct astronomical research on I’oligam Du’ag (Kitt Peak) in Arizona, on Maunakea in Hawai‘i, and on Cerro Tololo and Cerro Pachón in Chile. We recognize and acknowledge the very significant cultural role and reverence of I’oligam Du’ag to the Tohono O’odham Nation, and Maunakea to the Kanaka Maoli (Native Hawaiians) community.

---

Links

• Read the paper: Enrichment by the first stars in a relic dwarf galaxy
• Photos of the Víctor M. Blanco 4-meter Telescope
• Videos of the Víctor M. Blanco 4-meter Telescope
• Photos of DECam
• Check out other NOIRLab Science Releases

---

Contacts:

Anirudh Chiti
Brinson Prize Fellow
Stanford University
Email: achiti@stanford.edu

Josie Fenske
Public Information Officer
NSF NOIRLab
Email: josie.fenske@noirlab.edu

---