Strange winds reveal strongest hints yet of magnetic activity in exoplanets

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Artist’s impression of an exoplanet with a magnetic field

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How magnetic fields govern winds in exoplanets

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Strange winds reveal magnetic exoplanets | ESO News


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Animation of an exoplanet with a magnetic field


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How magnetic fields govern winds in exoplanets

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A team of astronomers has found the strongest evidence yet that some planets outside our Solar System may be magnetic. Using the European Southern Observatory’s Very Large Telescope (ESO's VLT) and the Gemini North telescope, the researchers measured wind speeds on seven very hot, Jupiter-like exoplanets. The observations revealed that the winds on these planets are most likely governed by magnetic fields, providing the first robust measurement of magnetism on planets outside the Solar System.

“This breakthrough opens a completely new window on exoplanet research. It’s the first time we can compare the magnetic environments of other worlds — a key step toward ultimately understanding which planets can stay alive, keep their water, and perhaps even, one day, host life as we know it,” says Julia Seidel, an astronomer at the Laboratoire Lagrange, Observatoire de la Côte d’Azur, France and lead author of the study published today in Nature Astronomy.

Earth’s magnetic field influences our atmosphere in complex ways, and is therefore a key factor in understanding what keeps the planet habitable for life. Magnetic fields are also present in other Solar System planets, like Jupiter and Saturn. However, for the past 15 years, no one succeeded in directly measuring the strength of the magnetic fields of exoplanets — until now.

The team, however, didn’t set out to measure magnetic fields but, rather, winds. They measured wind speeds on seven exoplanets orbiting different stars: gas giants like Jupiter, but each tidally locked to its host star and very close to it. Just as we always see only one side of the Moon, these planets always keep one face towards the star, resulting in a scorching hot day side and a freezing cold night side. This temperature difference creates a climate completely different from the one on our planet, with extremely strong winds. The wind speeds in their sample ranged from around 7200 km/h to over 25 000 km/h; in comparison, the fastest winds measured on Jupiter reach speeds of around 1500 km/h.

“In the beginning we set out to check if the atmospheric winds behaved the same way for all hot planets,” explains Seidel, who was previously an astronomer at ESO in Chile. For their measurements, the team used data from the ESPRESSO instrument on ESO’s VLT, in the Chilean Atacama Desert, and from a similar instrument on the Gemini North telescope in Hawaiʻi, USA. (The VLT is an ESO telescope while Gemini North is one half of the International Gemini Observatory, partly funded by the U.S. National Science Foundation (NSF) and operated by NSF NOIRLab.)

But when they looked at how the wind speeds varied with planet temperature, they saw a very intriguing pattern emerge: the hotter the planet, the slower the wind. “This is totally counter intuitive because, all things being equal, hot planets have more energy to accelerate the winds! Something must happen that slows down the wind speeds for hotter objects,” says study co-author Vivien Parmentier, a professor at the Laboratoire Lagrange.

The team concluded that the most consistent explanation for this mystery is the presence of planet-wide magnetic fields, since these fields can work as a brake, slowing down the motion of charged particles in the atmosphere. The data therefore allowed the researchers to infer the strength of the magnetic field in each of the studied planets. They found them to be comparable in strength to those found in our Solar System: approximately four times as strong as Saturn's or about half the strength of Jupiter's.

Such strong magnetic fields could affect more than just the wind on these distant planets. "Here on Earth, we know the beauty of the northern and southern lights, where particles from the Sun hit our magnetic field and are guided toward the poles, colliding with gases in the atmosphere to produce colourful displays of green, pink, and purple," explains study co-author Bibiana Prinoth, a former PhD student at Lund University, Sweden, now an astronomer at ESO in Garching, Germany. On the studied exoplanets, the magnetically driven aurorae could be even more dramatic. The team eagerly anticipates the arrival of ESO’s Extremely Large Telescope, which will help to characterise not only large, Jupiter-like exoplanets but also smaller ones like Earth, possibly even detecting gases that could produce aurorae on these distant worlds. Prinoth says: “I like to imagine that some of these worlds have a sky filled not only with stars, but with vast curtains of colourful light dancing across a planet that’s half in perpetual day and half in endless night.”

Source: ESO/News

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More information

This research was presented in a paper to appear in Nature Astronomy (doi:10.1038/s41550-026-02870-1).

The team is composed of Julia V. Seidel (European Southern Observatory, Santiago, Chile [ESO Chile]; Université Côte d’Azur, Observatoire de la Côte d’Azur, CNRS, Laboratoire Lagrange, France [Lagrange]), Vivien Parmentier (Lagrange), Bibiana Prinoth (Lund Observatory, Division of Astrophysics, Department of Physics, Lund University, Lund, Sweden[LU]), Thea Hood (Lagrange), Nishil Mehta (Lagrange), Valentin De Lia (Lagrange), Brian Thorsbro (Lagrange, LU), Konstantin Batygin (Division of Geological and Planetary Sciences, California Institute of Technology, USA), Tristan Guillot (Lagrange), Ragnar van den Broeck (Lagrange), Florian Debras (IRAP, Université de Toulouse, Toulouse, France), Daniel D. B. Koll (School of Physics, Peking University), Thaddeus Komacek (Department of Physics (Atmospheric, Oceanic and Planetary Physics), University of Oxford, Oxford, UK [Oxford]), Hayley Beltz (Department of Astronomy, University of Maryland, College Park, USA), Emily Rauscher (Department of Astronomy and Astrophysics, University of Michigan, MI, USA), Lorenzo Pino (INAF - Osservatorio Astrofisico di Arcetri, Florence, Italy), Matteo Brogi (Dipartimento di Fisica, Università di Ferrara, Ferrara, Italy; INAF – Osservatorio Astrofisico di Torino, Turin, Italy), Joost P. Wardenier (Département de Physique, Institut Trottier de Recherche sur les Exoplanètes, Université de Montréal, Canada [iREx]), Jacob L. Bean (Department of Astronomy & Astrophysics, University of Chicago, Chicago, USA [Chicago]), Björn Benneke (iREx and Department of Earth, Planetary, and Space Sciences, University of California, Los Angeles, CA 90095, USA), Jean-Michel L. B. Desert (Anton Pannekoek Institute for Astronomy, University of Amsterdam, Amsterdam, Netherlands), Pablo Drake (Lagrange), Siddharth Gandhi (Department of Physics, University of Warwick, Coventry, UK and Centre for Exoplanets and Habitability, University of Warwick, Coventry, UK), Mark Hammond (Oxford), David Kasper (Chicago), Michael R. Line (School of Earth and Space Exploration, Arizona State University, Tempe, USA [SESE]), Elspeth Lee (Center for Space and Habitability, niversity of Bern, Bern, Switzerland), Stefan Pelletier (Observatoire astronomique de l’Université de Genève, Versoix, Switzerland), Andreas Seifahrt (International Gemini Observatory/NSF NOIRLab, Tucson, USA), Adrien Simonnin (Lagrange), Peter Smith (SESE), and Kevin B. Stevenson (JHU Applied Physics Laboratory, Laurel, USA)

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.

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Contacts:

Julia Victoria Seidel
Lagrange Laboratory, Observatoire de la Côte d'Azur
Nice, France
Tel: +33 743 32 79 73
Email: jseidel@oca.eu

Vivien Parmentier
Lagrange Laboratory, Observatoire de la Côte d'Azur
Nice, France
Email: Vivien.PARMENTIER@univ-cotedazur.fr

Bibiana Prinoth
European Southern Observatory (ESO)
Garching bei München, Germany
Email: bibiana.prinoth@eso.org

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

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Simulations Explain Baby Carriage Wheels Around Baby Stars

Left: Observations of a star-forming region with a hub-and-spoke shape like a baby carriage wheel. Right: A similar shape produced by a simulation using the ATERUI III supercomputer. (Credit: M. S. N. Kumar, ESA/Herschel, NASA/JPL-Caltech (Spitzer), S. Nozaki, S. Inutsuka) Image (716KB)

Numerical simulation of the formation of a hub–filament system molecular cloud.

After an interstellar shock wave passes through a molecular cloud, multiple filaments characteristic of a hub–filament system develop radially toward the center. The left panels show the cloud viewed perpendicular to the propagation direction of the interstellar shock wave, while the right panels show the view parallel to the direction from which the shock wave approaches. The numbers in the upper left indicate the elapsed time since the start of the simulation. Note that the right panels are displayed using a different density range than the left panels in order to make the higher-density gas easier to distinguish. (Credit: Shingo Nozaki (Kyushu University))

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Research using multiple supercomputers, including ATERUI III at the National Astronomical Observatory of Japan, has found a possible explanation for the hub-and-spoke pattern seen in some molecular clouds where baby stars are forming. According to the new numerical simulations, if an external shock interacts with magnetic fields which have been warped by the motion of the clouds, gas can be channeled into a shape resembling the spokes on the wheels of a baby carriage.

When parts of molecular clouds become dense enough, they can collapse under self-gravity. As a result of this collapse, the gas in the clouds condenses into protostars which will grow into stars. For this reason, molecular clouds are nicknamed “stellar cradles.” But some of these sites of star formation are more like baby carriages than cradles because they have filaments of gas extending toward a central hub, forming a shape like a spoked wheel.

Researchers from Kyushu University and Nagoya University investigated the possibility that magnetic fields within the clouds might play a role in forming this distinct shape. Using ATERUI III, a dedicated-astronomy supercomputer operated by the National Astronomical Observatory of Japan, they modeled how gas and magnetic fields evolve together over time. The results show that as the cloud collapses under self-gravity, it pulls the magnetic field lines inward, bending them into an hourglass shape. The team then simulated the effects of a disturbance like a shock wave from a nearby supernova remnant or from expanding gas around a massive star. The team found that if this shock hits the curved magnetic field at certain angles, it strengthens parts of the magnetic field, forming invisible channels that guide compressed gas into long, narrow filaments converging toward the center.

The team now plans to conduct more simulations to test whether this mechanism can explain more asymmetric and complex shapes. This will help clarify how the diversity of observed hub-filament systems reflects differences in cloud environments and how such environments shape the formation of massive stars and clusters.

Source: National Astronomical Observatory of Japan (NAOJ)/News

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Detailed Article(s)

Simulations Explain Baby Carriage Wheels Around Baby Stars
Center for Computational Astrophysics

Release Information

Researcher(s) Involved in this Release

Shingo Nozaki (Kyushu University)
Shu-ichiro Inutsuka (Nagoya University)

Coordinated Release Organization(s)

Kyushu University
Nagoya University
National Astronomical Observatory of Japan, NINS

Paper(s)

Shingo Nozaki and Shu-ichiro Inutsuka “An Origin of Radially Aligned Filaments in Hub-filament Systems”, in Astrophysical Journal Letters, DOI: 10.3847/2041-8213/ae4c84

Related Link(s)

Scientists show how baby stars' cradles get their radial shape (Kyushu University)

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Hubble spies faint irregular galaxy ESO 490-017

This NASA Hubble Space Telescope image captures the faint glow of the dwarf irregular galaxy ESO 490-017.
Credit: NASA, ESA, R. Tully (University of Hawaii); Image Processing: G. Kober (NASA/Catholic University of America)

This NASA Hubble Space Telescope image features the dwarf irregular galaxy ESO 490-017, roughly 12,000 light-years in diameter and some 23 million light-years away in the constellation Canis Major. The galaxy's low surface brightness makes it appear as a faint, starry swarm behind brighter foreground stars that are easily recognized by their diffraction spikes. Numerous red, orange, and beige dots are distant galaxies peppering the black background, many exhibiting distinct spiral structure.

The data in this image of ESO 490-017 was part of a Hubble observing program that looked at the movement of galaxies and galaxy clusters through space. Matter in the universe is distributed unevenly, and the gravitational influence of that matter drives the "cosmic flow" or movement of large-scale structures in the universe.

Hubble is uniquely capable of providing distances to nearby galaxies like ESO 490-017 by measuring the luminosities of low-mass red giant stars as "standard candles." The observing program also provided a legacy archive of the types of stars in local galaxies.

Provided  by Claire Andreoli,  NASA

edited by Gaby Clark, reviewed by Robert Egan

Source: Phys.org/News

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Explore further

Hubble captures galaxy cluster MACS J1141.6-1905

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NASA’s Webb Reveals Black Hole That Formed Before Its Galaxy

Little Red Dot Abell2744-QSO1 (NIRCam Image)

An image from NIRCam on NASA’s James Webb Space Telescope shows Little Red Dot Abell2744-QSO1, magnified and triply imaged by galaxy cluster Abell 2744 (Pandora’s Cluster). Credit Image: NASA, ESA, CSA, Lukas Furtak (Ben-Gurion University); Image Processing: Alyssa Pagan (STScI)

Little Red Dot Abell2744-QSO1a (NIRCam Image with NIRSpec IFU Velocity Map)

An image detail from NIRCam (left) on NASA’s James Webb Space Telescope shows Little Red Dot Abell2744-QSO1. A map of gas velocity in QSO1 (right), made using the IFU on NIRSpec, shows evidence for a 50-million-solar-mass black hole at the center. Credit Image: NASA, ESA, CSA, Ignas Juodžbalis (Cambridge), Cosimo Marconcini (University of Florence), Roberto Maiolino (Cambridge), Francesco D'Eugenio (Cambridge), Hannah Übler (MPE); Image Processing: Alyssa Pagan (STScI)

Little Red Dot Abell2744-QSO1 (NIRCam Compass Image)

Image of Abell 2744 and Little Red Dot Abell2744-QSO1, captured by Webb’s NIRCam, with compass arrows, scale bar, and color key for reference. Credit Image: NASA, ESA, CSA, Lukas Furtak (Ben-Gurion University); Image Processing: Alyssa Pagan (STScI)

Little Red Dot Abell2744-QSO1: Sonification of Gas Velocity Around a Supermassive Black Hole (NIRCam and NIRSpec IFU)

A sonification is a translation of data into sound. In this sonification, the velocity of hydrogen gas moving around a black hole in the center of a Little Red Dot known as Abell2744-QSO1 (QSO1) is translated into sounds of varying pitch (or frequency). The faster the gas is moving toward the telescope, the higher the pitch. The faster it is moving away from the telescope, the lower the pitch. Credit Sonification: NASA, ESA, CSA, STScI, Christopher Britt (STScI), Ralf Crawford (STScI), Alyssa Pagan (STScI), Margaret Carruthers (STScI); Science: Ignas Juodžbalis (Cambridge), Cosimo Marconcini (University of Florence), Roberto Maiolino (Cambridge), Francesco D'Eugenio (Cambridge), Hannah Übler (MPE)

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Which comes first, the galaxy or the black hole? We don’t know, but scientists have long thought it could be the galaxy: Large stars within an existing galaxy consume their fuel and collapse to form black holes, which can gobble up surrounding material and merge over time to form more massive entities.

But it’s hard to figure out how black holes millions to billions of times the mass of the Sun, thousands of which have now been detected in the early universe, could have grown so quickly from such small seeds.

Now, researchers using NASA’s James Webb Space Telescope have detected clear evidence that some supermassive black holes were enormous from the beginning, forming without a stellar collapse phase, and without a significantly more massive host galaxy to feed them.

“This is a remarkable finding,” said Roberto Maiolino of University of Cambridge in the United Kingdom, co-author of studies published in Nature and the Monthly Notices of the Royal Astronomical Society. “It’s a paradigm shift, a total revisiting of the classical scenarios of how black holes form and grow.”

Little Red Dot QSO1

The team’s conclusion is based on detailed observations of Abell2744-QSO1 (QSO1), a prototypical Little Red Dot that existed just 700 million years after the big bang.

Although QSO1 is only 1,300 light-years across, and its light has been traveling for more than 13 billion years, it is easier to study than most other Little Red Dots because it is gravitationally lensed by galaxy cluster Abell 2744 (Pandora’s Cluster). QSO1 is both magnified and triply imaged, appearing in three different locations in the sky.

Initial studies of QSO1 revealed compelling evidence that it may be little more than a cloud of glowing hydrogen and helium gas circling a supermassive black hole estimated at 40 million times the mass of the Sun. But as with other early black holes discovered by Webb, there was uncertainty about whether it really was that massive. “Before now, all of the mass measurements of black holes in the early universe have been indirect, based on assumptions from what we know about them in the local universe. We didn’t know if those assumptions really apply to the distant universe,” said co-author Francesco D’Eugenio, also of the University of Cambridge.

Mapping gas composition, velocity

The team recognized that if QSO1’s black hole is as massive as it looks, they should be able to use the integral field unit (IFU) on Webb’s NIRSpec (Near Infrared Spectrograph) to trace the effects of its gravity on the gas swirling around it, while also mapping the distribution of various elements in the gas.

Cambridge graduate student Ignas Juodžbalis and Cosimo Marconcini of the University of Florence, lead authors on one of the studies, used the IFU observations to map motions of hydrogen gas surrounding the black hole. When they plotted the rotation velocity as a function of distance from the center, they found that the gas has Keplerian motion: It orbits a central point in the same way that planets in our solar system orbit the Sun.

“This is important because it tells us that most of the mass of QSO1 is concentrated in the black hole at the center,” said Juodžbalis. “If the mass were more distributed, as it would be if there were a lot of stars, the gas would not have this perfect Keplerian rotation.”

Since Keplerian motion is governed by simple laws of gravity, the team was able to use the gas velocity measurements to calculate the black hole mass directly, a feat that had not previously been possible.

They found that not only is the black hole immense — roughly 50 million solar masses — it makes up, at minimum, an astonishing two-thirds of QSO1’s total mass. This proportion is thousands of times greater than in nearby galaxies, where supermassive black holes make up only a tiny fraction of the host galaxy’s total mass.

The IFU composition maps supported these results, showing that the gas throughout QSO1 is almost entirely hydrogen and helium, with very little of the heavier elements like oxygen that would be expected in a galaxy rich with stars and stellar debris. With a metallicity less than 0.5% of the Sun, QSO1 is one of the most pristine galactic environments ever measured.

“This is a phenomenal result,” said Maiolino. “It is the first direct measurement of a black hole mass within the first billion years after the big bang, and it is consistent with the previous measurements.” The team thinks this is a good sign that the assumptions used for indirect mass measurements are valid and the masses of other black holes in the early universe have not been overestimated.

Supermassive black hole origins

The team recognized that if QSO1’s black hole is as massive as it looks, they should be able to use the integral The outsized mass of QSO1 relative to its host galaxy suggests that it can’t have formed gradually from much smaller, stellar-mass black holes merging and feeding. “It seems that we have found a black hole that does not have a substantial host galaxy and that has predated stellar processes,” said Juodžbalis. “This is very exciting because it is evidence for primordial black holes or direct collapse black holes, which have been theorized but not confirmed.”

Whether QSO1’s black hole evolved from a “heavy seed” that formed within the first second of the big bang or somewhat later from the collapse of a giant cloud of gas, it was almost certainly born big, and may be in the early stages of building a galaxy around it.

The team thinks that Little Red Dots like QSO1 cannot have been rare in the early universe, and is in the process of analyzing similar objects to find out whether supermassive black holes actually do predate the galaxies where they currently reside.

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

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Related Links

Watch: NASA Black Hole Visualization Takes Viewers Beyond the Brink

Explore more: ViewSpace | Black Holes: Searching for the unseen

Read more: Dissecting Supermassive Black Holes

Watch: What Webb Learns from Light

Explore more: NASA's Universe of Learning: Black Hole Resources

More Webb News

More Webb Images

Webb Science Themes

Webb Mission Page

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I Spy with My Large Binocular Eyes: A Dusty Torus Around a Supermassive Black Hole?

Hubble Space Telescope image of the active galaxy NGC 4151.
Credit: NASA, ESA, Joseph DePasquale (STScI)

Title: Shocks, Winds, and a Torus: The Large Binocular Telescope Interferometer (LBTI) Resolves the Active Nucleus of NGC 4151

Authors: Jacob W. Isbell et al.
First Author’s Institution: University of Arizona
Status: Published in ApJ

At the centre of nearly every galaxy lies a supermassive black hole that dominates this innermost region. Not only is there this millions-of-solar-masses dark beast, but usually too a whole bunch of stuff — stars, gas, dust, and more — which is often quite bright! When there is plenty of this material quite close to the black hole, we believe physics takes control to flatten it into a family of disk and toroidal structures in what we call the unified model of active galactic nuclei (AGNs; see Figure 1).

Figure 1: The unified model of AGNs asserts that there is an inner accretion disk, surrounded by a dusty torus that cohabitates with clouds moving at different velocities (the so-called broad and narrow line regions), and sometimes even relativistic jets extending from the accretion disk to galactic scales; you can read more about AGN structure in this Astrobites guide. Credit:  Emma Alexander; CC BY 4.0

When astronomers look at different active galaxies (read: galaxies with active supermassive black holes at their core), we see a range of phenomenologies related to their brightness, spectra, morphologies, and more. The unified model of AGNs seeks to explain these different AGN appearances simultaneously by positing that they all have the same physical structure, and we are just viewing them from different angles, hence seeing different features.

The cores of AGNs are often imaged at the smallest scales (e.g., their accretion disks, viewed with interferometers like the Very Large Telescope Interferometer) and the largest scales (e.g., their relativistic jets, viewed with radio interferometers), but comparatively less effort has gone to directly observing the predicted dusty tori in the mid-infrared. That is exactly what today’s authors set out to do using the Large Binocular Telescope Interferometer (LBTI) — a pair of 8.4-metre-aperture mirrors separated by just over 14 metres and combined to simulate a telescope effectively 29 metres wide. This lets astronomers take direct images at a much higher resolution than a smaller-aperture telescope, and hence directly peer into the region around AGNs where this dusty torus should lie.

Today’s authors turn the LBTI towards NGC 4151, a medium-luminosity AGN. With the large effective aperture of the LBTI, they were able to resolve scales in the AGN region as small as 4.4–9.1 pc, about 14–30 light-years depending on the wavelength (see Figure 2), in the mid-infrared. These observations revealed warm dust emission in a complex structure around the central supermassive black hole. The authors note a central bar at all wavelengths, with a significant extension of cool dust arcing to the west (right in the image) and warmer dust localised to the centre (as evident by 3.7- and 4.8-micron emission only nearest to the supermassive black hole and its accretion disk).

Figure 2: The deconvolved images of the AGN core of NGC 4151 show a very bright central source (the innermost region around the supermassive black hole), as well as some complex surrounding structure particularly at long wavelengths. The interpreted morphology is described in Figure 3. These images are deconvolved, meaning that known optical effects are corrected for on the raw data to produce a sharper image. Adapted from Isbell et al. 2026

To explain the observed morphology in Figure 1, the authors compare three different interpretations based on this new high-resolution imagery together with the results of previous studies looking at other scales and the spectrum of the AGN core. Each interpretation is illustrated and briefed in Figure 3.

Figure 3: Three interpretations of the observed morphology are presented by the authors. The left panel illustrates the different regions surrounding the supermassive black hole (together with the results of other studies cited in the article). The right panel shows the suggested interpretations explaining the morphology. Credit: Isbell et al. 2026

The first interpretation is in keeping with the unified model of AGNs: a geometrically and optically thick torus of dust surrounds the inner region. In this interpretation, the surface of the dusty torus re-radiates light from the accretion disk to produce most of the mid-infrared emission. Additional mid-infrared emission could come from localised concentrations of gas or interactions between the outflow and the jet. The authors immediately disfavour this explanation, as other studies have shown bright ionised emission at the location of the would-be torus, which is not expected if an optically thick torus were to be present. Hence, these new observations somewhat challenge the one “flavour” of the unified model of AGNs.

The second interpretation aligns with a different version of the unified model: one in which a geometrically thin disk replaces a thick torus around the AGN core. Provided the disk is optically thin too, the authors favour this approach as it is consistent with the geometry of ionised emission that worked against the first interpretation. While other studies suggest that this thin disk should be optically thick, this morphology is at least better aligned with what we see in other AGNs.

The third interpretation suggests that the emission comes from only the radiation pressure–driven wind emanating from the AGN core. The authors disfavour this explanation, citing previous radiative transfer simulations that show that the flux should fall off with distance from the core too quickly to be consistent with the observations.

No matter the interpretation, these LBTI observations are an important glimpse into the future of mid-infrared AGN studies that will be done with 30-metre-class telescopes (such as the European Southern Observatory’s Extremely Large Telescope). This article, together with the group’s similar study on NGC 1068, is challenging and refining an accepted view of AGN morphology — the consequences of which apply to galaxies near and far — and poses new questions perfect for sophisticated hydrodynamic and radiative simulations.

Original astrobite edited by Margaret Verrico.

Source: American Astronomical Society/AAS-Nova

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About the author, Ryan White:

I am a first-year PhD student at Macquarie University in Australia, working mainly on binary/multiple systems with massive stars (Wolf–Rayets in particular!). Outside of study, I’m probably drinking coffee, baking, reading, or going for a run. You can also find me procrastinating on Bluesky @astroryan.bsky.social.

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Editor’s Note: Astrobites is a graduate-student-run organization that digests astrophysical literature for undergraduate students. As part of the partnership between the AAS and astrobites, we occasionally repost astrobites content here at AAS Nova. We hope you enjoy this post from astrobites; the original can be viewed at    astrobites.org.

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Just 1.2 Billion Years After the Big Bang, Galaxies Were Already Shaped by Where They Lived

Figure 1: The Loktak Protocluster Region. A false-color composite image combining visible-light observations from the Hubble Space Telescope with infrared observations from JWST. White dots mark galaxies identified by the Subaru Telescope, while orange shading indicates regions where galaxies are densely concentrated. Colored contours show galaxy number density relative to the cosmic average at that time: 2 times (pink), 5 times (green), 8 times (blue), and 10 times (black). The white dashed line outlines the full extent of the Loktak Protocluster. The close-up images in the red and blue boxes show examples of galaxies in dense environments and in typical environments, respectively. A high resolution image is available here (5.2 MB). (Credit: Laishram et al./NAOJ/NASA/ESA/CSA)

Figure 2: Distribution of galaxy sizes for galaxies in the central region of the Loktak Protocluster (red) and galaxies in average environments at the same epoch (blue). Left: ultraviolet measurements. Right: optical measurements. In optical light, galaxies in the dense environment are larger. A value of 1 on the horizontal axis corresponds to the typical galaxy size in average environments. (Credit: Laishram et al./NAOJ)

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A large protocluster of galaxies that existed 12.6 billion years ago, first discovered with the Subaru Telescope, has been examined in detail using the James Webb Space Telescope (JWST). The study found that galaxies in crowded regions are more extended than similar galaxies in less dense environments. The result shows that even when the Universe was only 1.2 billion years old, environment was already influencing how galaxies grew.

How Did the Universe’s Largest Structures Form?

In today’s Universe, galaxies are not spread evenly through space. They have gathered into groups, and those groups form enormous galaxy clusters containing hundreds or even thousands of galaxies. But these giant structures did not exist at the beginning of the Universe.

In the early Universe, slightly denser regions of matter gradually grew under gravity and eventually developed into galaxy clusters. These "seeds" of galaxy clusters are known as protoclusters.

One of the key questions for astronomers is when did dense environments begin to influence how galaxies evolve.

In the modern Universe, galaxies in clusters often look very different from isolated galaxies. They tend to be more massive, have difficulty forming new stars, and have rounder shapes. This phenomenon—where galaxy growth depends on its surroundings —is known as an environmental effect.

However, it has remained unclear whether such effects were already present in the very early Universe, or whether they appeared only after galaxy clusters had fully matured.

The Loktak Protocluster Discovered by the Subaru Telescope

An international research team including astronomers at the National Astronomical Observatory of Japan (NAOJ) used the Subaru Telescope’s wide-field camera, Hyper Suprime-Cam (HSC), to conduct a large sky survey and discovered a massive protocluster that existed 12.6 billion years ago.

Young galaxies with active star-formation often emit a special type of light called Lyman-alpha emission. This emission is produced when radiation from hot young stars excites surrounding hydrogen gas. Galaxies found through this signal are called Lyman-alpha emitters, and they are useful markers for tracing structure in the early Universe.

Using a special filter tuned to detect this light, the team mapped a vast area of sky and identified a region where galaxies were strongly concentrated.

The newly discovered structure was named the Loktak Protocluster, after Loktak Lake in Manipur, India. The name reflects the way four separate galaxy concentrations are linked together into one larger structure, resembling the floating islands of the lake (Figure 1). "Protoclusters are the construction sites of the most massive structures in the present-day Universe," says lead author Ronaldo Laishram of NAOJ. "Finding such a clearly organized system at this early epoch gives us a rare chance to study how environment affects galaxy growth in the young Universe."

JWST Reveals Differences in How Galaxies Grew

The team then used JWST infrared images to compare galaxies inside the protocluster with galaxies in more typical environments at the same cosmic epoch.

When observed in ultraviolet light—which traces regions where stars are forming—the two galaxy populations showed little difference in size. However, in optical light (Note 1), which traces the overall distribution of previously formed stars, galaxies in the protocluster were on average about 1.4 times larger than galaxies in normal environments (Figure 2, Note 2).

In other words, although the star-forming cores looked similar, the overall galaxies had grown differently. This suggests that star formation in galaxy centers proceeded similarly, but galaxies in dense environments built up their outer stellar structures earlier and more rapidly.

A Galaxy’s Fate Depends on Where It Lives

The importance of this result is that it clearly shows environmental effects were already shaping galaxies long before galaxy clusters were fully formed.

Out of the Universe’s current age of 13.8 billion years, the galaxies observed here are seen only 1.2 billion years after the Big Bang. Even at that very early time, how a galaxy grew depended on where it lived. This means galaxy evolution is determined not only by a galaxy’s own mass and internal properties, but also by its surroundings from an early stage.

The study suggests that the appearance of galaxies is shaped not only by what they are born with, but also by where they grow up—and that this process began in the earliest chapters of cosmic history.

Future observations using Subaru Telescope’s ʻŌnohiʻula PFS as well as the next-generation wide-field adaptive optics system (ULTIMATE), combined with continued JWST follow-up will help determine whether this kind of environmental effect was common in the early Universe or unique to the Loktak Protocluster.

These results appeared in The Astrophysical Journal Letters on April 27, 2026 (Laishram et al. "Discovery of a z ≃ 4.9 Lyα Emitter Protocluster: Wavelength-dependent Environmental Effects on Galaxy Structure").

This work was supported by JSPS KAKENHI grants (23H01219, 24H00002, 22K21349) and the JSPS Core-to-Core Program (JPJSCCA20210003).

Source: Subaru Telescope

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Notes:

(Note 1) Because light from distant galaxies is stretched to longer wavelengths by the expansion of the Universe, light emitted as visible light reaches Earth as infrared light. JWST’s highly sensitive infrared instruments make it possible to study the visible-light structure of distant galaxies.

(Note 2) In general, more massive galaxies tend to be larger. However, the size difference found in this study cannot be explained by mass differences alone.

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About the Subaru Telescope

The Subaru Telescope is a large optical-infrared telescope operated by the National Astronomical Observatory of Japan, National Institutes of Natural Sciences with the support of the MEXT Project to Promote Large Scientific Frontiers. We are honored and grateful for the opportunity of observing the Universe from Maunakea, which has cultural, historical, and natural significance in Hawai`i.

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Double Boomerang

This image of galaxy PKS 2014-55, located 800 million light years from Earth, was made by NRAO scientist William Cotton with the South African Radio Astronomy Observatory (SARAO) MeerKAT telescope. It shows for the first time how the galaxy’s X-shape is actually a ‘double boomerang’. Two powerful jets of radio waves, indicated in blue color, originate from a massive black hole at the center of the galaxy. They each extend 2.5 million light years into space (comparable to the distance between the Milky Way and the Andromeda galaxy, our nearest major neighbour). Eventually, the jets are ‘turned back’ by the pressure of tenuous intergalactic gas. As they flow back towards the central galaxy, they are deflected by its relatively high gas pressure into the shorter, horizontal arms of the boomerang. The background image shows visible light from myriad galaxies in the distant universe. Credit: NRAO/AUI/NSF, S. Dagnello & W. Cotton; SARAO; DES

Hi-Res Full-Size 5861 x 5861 13 MB

Technical Details

Telescope: MeerKAT

Center: RA: 20:18:01.3, Dec: -55:39:31.5

Field of View: 24.53 x 24.53 arcminutes

Source: National Radio Astronomy Observatory (NRAO)/Image of the Week

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Supermassive black hole accretion flow

An artist’s impression of a supermassive black hole, with intense radiation blasting out across the accretion disk of matter flowing into it. Image credit: NASA/JPL-Caltech. Download Image

A key question in studies of Active Galactic Nuclei (AGN) is the nature of the accretion flow around the supermassive black hole, which is still poorly understood. NGC 4051 offers a rare opportunity to observe this process around a low-mass AGN, which is also one of the brightest of its class. Its unique combination of variability, lower black hole mass, and accessibility to monitoring makes it an ideal laboratory for testing models of the innermost structure of AGN. A critical open question is the role of X-rays in irradiating the accretion disk, and how this effects the total energy observed in the system. For this purpose, NuSTAR's broad energy coverage and sensitivity are ideal for obtaining a high-quality X-ray spectrum. The NuSTAR observation performed last week completes the measurement of the broadband spectral energy distribution for NGC 4051 and is a key component to the 3-month multi-wavelength monitoring campaign of this interesting source that is currently underway.

Author: Marcin Marculewicz (Postdoctoral Fellow, Wayne State University)

Source: NASA's Nuclear Spectroscopic Telescope Array (NuSTAR)/Weekly Highlights

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A twinkling pulsar reveals invisible structures in space

The linear structure is the visible scattering of the pulsar PSR B1508+55, which is located at the center of the image. The invisible interstellar medium—the thin material between the stars—causes this distortion, which also results in changes in brightness over a period of several hours. The intensity of the radiation is color-coded and increases from violet through red to orange. © Tim Sprenger / MPIfR

The radio image from December 5, 2023, shows the point-like pulsar (center of the image), whose radiation is scattered into a line. The distinct shape indicates that the scattering gas between us and the pulsar is not randomly distributed. Instead, it exists in structures with a preferred orientation—such as folded thin layers. The image was obtained at radio frequencies between 1300 and 1425 megahertz. © Tim Sprenger / MPIfR

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To the point:

• An international team led by Tim Sprenger of the Max Planck Institute for Radio Astronomy (MPIfR) observed the flickering of a pulsar’s radio radiation with two of the world’s most powerful radio telescopes.


• The shape of the distorted image allows us to conclude that the thin gas between us and the stellar remnant is not randomly distributed, but rather exists in structures with a preferred orientation.


• The observational technique allows for the capture of high-resolution images without the need to link telescopes around the globe in a data- and computation-intensive manner.

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Fluctuations in brightness and the elongated appearance of a stellar remnant indicate that its radiation is being scattered within an unidentified interstellar cloud located 430 light-years from Earth.

The twinkling stars in the night sky are not just beautiful to look at. Their flickering reveals something about the varying temperatures and densities in the layers of Earth’s atmosphere, which refract the light as it travels toward us. Certain stellar remnants that emit radio waves can exhibit a very similar effect. Although their radio waves—which have longer wavelengths than visible light—can penetrate Earth’s atmosphere almost undisturbed, they are scattered by the thin gas between the stars. Their twinkling—known as scintillation—thus provides unique insights into interstellar space.

An international team led by Tim Sprenger from the Max Planck Institute for Radio Astronomy (MPIfR) measured the flickering radio radiation from an object using an innovative observation technique. The results are published in the current issue of the journal Astronomy & Astrophysics.

Flickering Stellar Remnants

Scintillation occurs only in point sources, which is why distant stars twinkle but planets do not. In the radio spectrum, flickering can be observed in pulsars—the remnants of massive stars. They are among the most compact objects in the universe: the mass of an entire star is compressed into a sphere with the diameter of a major city. The radio signals emitted by pulsars fluctuate in brightness due to scintillation, and their position in the sky appears smeared. The pulsar observed in the current study is only the second one in which the distortion caused by scintillation could be directly imaged.

Unexpectedly straight

The research team led by Tim Sprenger observed the pulsar designated PSR B1508+55, located about 7,000 light-years away in the constellation Draco. In the long-exposure image, the pulsar appears distorted into a line. “Usually, one imagines that the pulsar is distorted into a blurred disk by random density fluctuations. Instead, the interstellar medium here seems to form ordered structures with a preferred orientation,” explains lead author Tim Sprenger. These could be, for example, parallel filaments or thin, folded layers.

Exactly what the structures look like in this case is not yet clear. This is partly because the observed scattering they cause is very small on an astronomical scale and difficult to observe. Of particular interest are small irregularities in the otherwise straight scattered line. “Observing the contrast between the primary linear image and its complex deviations is fascinating. It makes us wonder: what are the microscopic structures that created them—structures that elude our current picture of the interstellar medium?", adds co-author Xun Shi from Yunnan University in China. Using model calculations, it is at least possible to determine that the interstellar cloud is located about 430 light-years from Earth.

Groundbreaking Observation Technique

The scintillation of a pulsar causes such small positional changes that they cannot be spatially resolved with individual telescopes. The researchers therefore used a sophisticated observational technique and two of the world’s most powerful radio telescopes: The 100-meter Effelsberg radio telescope in Germany and the Five-hundred-meter Aperture Spherical radio Telescope (FAST) in China. Due to Earth's motion, when both telescopes are pointed simultaneously at PSR B1508+55, their positions change significantly over time.

This means that, over the course of a day, sometimes one telescope and sometimes the other sees the same flickering first, depending on whether Germany or China is currently pointing more in the direction of the Earth’s motion. From this, an image can be calculated. Co-author Olaf Wucknitz adds: “Taking advantage of the large distance between the two radio telescopes and of the Earth’s motion relative to the observed structures, we were able to achieve a resolution that is not possible with any other technique in the observed frequency range.”

At higher frequencies, comparable resolutions can be achieved by combining many telescopes around the world into a virtual telescope. This is technically complex, and the resulting data must be correlated in a time-consuming process. “The observation technique we used does not place high demands on the infrastructure. It works with locally processed data sets that we were able to merge using our standard laptops,” reports Tim Sprenger. Following this success, observations of additional pulsars are planned. These should then reveal more about the invisible structures of the interstellar medium. Michael Kramer, Executive Director of the MPIfR, points out that FAST is currently the most sensitive telescope in the world, emphasising: “This beautiful work demonstrates what’s possible when two of the most powerful instruments in the world are working together. Both telescopes are great, but their rare combination is even far better!”

Source: Max Planck for Radio Astronomy/Press Releases

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Additional Information

The following scientists affiliated to the MPIfR are co-authors of this publication: Tim Sprenger and Olaf Wucknitz.

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Contacts:

Dr. Tim Sprenger
Tel: +49 228 525-319
Email: tsprenger@mpifr-bonn.mpg.de

Dr. Olaf Wucknitz
Tel: +49 228 525-481
Email: wucknitz@mpifr-bonn.mpg.de

Dr. Nina Brinkmann
Press and Public Relations
Tel: +49 228 525-399
Email: brinkmann@mpifr-bonn.mpg.de

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Original publication

Sprenger, T. et al.
Imaging without visibilities – FAST-Effelsberg scintillometry of PSR B1508+55
Astronomy & Astrophysics 709 (2026)

DOI

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Graphics

• b1508_images_2023 (46.5 kB)
• b1508_images_2023_de (47.75 kB)
• imaged_scattering (108.67 kB)

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The Origins of Nereid, Neptune's Most Eccentric Moon

Neptune

The Orbits of Neptune's Moons

Short movie showing the orbits of Nereid, Triton, and the inner moons of Neptune. The innermost moons all orbit in the plane of Neptune's equator. Triton orbits the other way, with a significantly inclined orbit. Nereid is much further out, with a highly eccentric, or elliptical, orbit. Made using Universe Sandbox. Credit: M. Belyakov

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Neptune, the farthest of the planets, acts like a shepherd for the outer solar system, gravitationally scattering distant asteroids known as Kuiper Belt Objects (KBOs). Understanding Neptune's history gives important clues to how the rest of the solar system evolved to its present state.

Neptune itself is unique—tilted 30 degrees on its side, it is host to a few unusual moons, including the Pluto-sized moon called Triton. Triton orbits Neptune backward, an indicator that it did not form around Neptune but was instead captured by Neptune's gravity after it formed elsewhere in the solar system. New observations coupled with simulations of Neptune's evolutionary history indicate that an oft-overlooked Neptunian moon called Nereid may reveal the planet's past.

The research was led by graduate student Matthew Belyakov and conducted as a collaboration between the laboratories of Professor of Planetary Science Konstantin Batygin (PhD '12), and Mike Brown, the Richard and Barbara Rosenberg Professor of Planetary Astronomy and Terence D. Barr Leadership Chair and director of the Center for Comparative Planetary Evolution. The work is reported in a paper appearing in Science Advances on May 20.

Jupiter, Saturn, and Uranus all have "typical" moon systems, with each planet possessing several large moons that orbit closely and along the host planet's equatorial plane, as well as many smaller moons, called irregular satellites, located farther out on tilted or "inclined" orbits. Neptune, on the other hand, has just one large moon, Triton, that contains 99.9 percent of the mass in its entire moon system. Triton's orbit is retrograde—it moves clockwise, while Neptune orbits the Sun counterclockwise. This means that Triton could not have coalesced in place, as Jupiter and Saturn's moons did, out of the disk of material orbiting counterclockwise around its planet. Instead, Triton is thought to be a Kuiper Belt Object, like Pluto, that was flung into Neptune's path and ensnared gravitationally.

Prior to Voyager 2's flyby of Neptune in August 1989, only one other moon was known around Neptune, Nereid. Discovered by Dutch astronomer Gerard Kuiper in 1949, Nereid has since presented a mystery. The moon follows an eccentric orbit, swinging around Neptune in an ellipse, and is far from its planet, but not nearly as distant as irregular satellites around the other giant planets. Interestingly, Nereid does not have a 14retrograde orbit like Triton, and its orbit is much less inclined than other irregular moons in the solar system. Given these details, scientists debated Nereid's origin for 70 years, unable to conclude whether the moon was captured or formed in place.

In 2024, Caltech graduate students Matthew Belyakov and M. Ryleigh Davis (MS '22) used the James Webb Space Telescope (JWST) to observe the Neptunian moon system, with Nereid as one of the targets. The team used JWST's near-infrared spectrograph, which splits light into its many wavelengths in order to obtain chemical information about astronomical targets. Nereid's spectrum appeared rather different from that of Kuiperbelt objects—Nereid was instead more similar to the moons of Uranus. Informed by the observational data, which hinted toward a noncaptured origin for Nereid, Belyakov then developed simulations of the evolution of Neptune's moons.

The simulations showed that as Triton crashed into the Neptunian system and was captured, existing Neptunian moons could have been kicked out on eccentric orbits that looked identical to ereid's. This suggests that Nereid formed in situ around Neptune, rather than being a captured foreign object.

"Understanding what transpired at Neptune is one of the ways that we can solve what happened in the early solar system, and Nereid is important for pinning down key events like Triton's capture," Belyakov says. "We're hoping this work motivates people to do creative observations of Nereid, even though it is faint and distant. It's just as important as Triton. I hope Nereid will be visited by a mission within my lifetime."

Without such a mission, much about Nereid is likely to remain a mystery.Voyager images of Nereid are only a few pixels across. In continuation of their work, the team aims to build more simulations to constrain the timing of Triton's capture and the possible configurations for the initial moon system around Neptune.

The paper is titled "Nereid as a Regular Satellite of Neptune." In addition to Belyakov, Batygin, Brown, and Davis, former Caltech graduate student Ian Wong (PhD '18), now of the Space Telescope Science Institute in Baltimore, Maryland, is a co-author. Funding was provided by NASA, the European Space Agency, and the Canadian Space Agency, which jointly operate JWST.

Written by Lori Dajose

Source: Caltech/News

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Contact:

Lori Dajose
(626) 395‑1217
ldajose@caltech.edu

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Gaze into the Crystal Ball Nebula and See the Light Emitted by a Dying Star 1500 Years Ago

PR Image noirlab2613a
NGC 1514: The Crystal Ball Nebula

PR Image noirlab2613b
Star Trails Above Gemini North

PR Image noirlab2613c
NGC 1514 finder chart

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Videos


PR Video noirlab2613a
NGC 1514: The Crystal Ball Nebula


PR Image noirlab2613b
Star Trails Above Gemini North


PR Image noirlab2613c
NGC 1514 finder chart


PR Video noirlab2613d
Cosmoview Episodio 108: Nebulosa Bola de Cristal >
in English only

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The cosmic splendor of NGC 1514 is revealed in this new image from the Gemini North telescope in Hawai‘i

The 8.1-meter Gemini North telescope, located on the summit of Maunakea in Hawai‘i, has captured NGC 1514, nicknamed the Crystal Ball Nebula, in awe-inspiring detail. This nebula, with its mesmerizing glow of gas, harbors hints of a past stellar death, and its asymmetrical shell is now being shaped by the pair of binary stars that lie at its center.

NGC 1514, nicknamed the Crystal Ball Nebula, is showcased in this enchanting image captured by Gemini Multi-Object Spectrograph (GMOS) on the Gemini North telescope, located on Maunakea in Hawai‘i. Gemini North is one half of the International Gemini Observatory, partly funded by the U.S. National Science Foundation (NSF) and operated by NSF NOIRLab.

German–British astronomer William Herschel discovered the Crystal Ball Nebula in 1790. It’s located in the constellation Taurus, near the border of Perseus. While, culturally, crystal balls are known for divining the future, the Crystal Ball Nebula provides us with a snapshot of the final stages of a star’s life from long ago. It sits around 1500 light-years from Earth. This means the light captured in this image left its source around 1500 years ago, traveling across the Universe before finally reaching Gemini North.

The Crystal Ball Nebula is categorized as a planetary nebula, a nomenclature first presented by the nebula’s discoverer, William Herschel. He coined the term in the 1700s after spotting the spherical shape of these objects, which reminded him of planets. In reality, planets and planetary nebulae are unrelated.

Planetary nebulae form when a low- or intermediate-mass star ejects its outer layers near the end of its life, forming a somewhat spherical cloud of gas. They typically have smoother, spherical shapes, making the Crystal Ball Nebula unique for its bumpy shells of gas. As the central star casts away this gas, its inner core is exposed. Radiation from the core energizes the gas, giving it a scorching temperature and chromatic glow. The Crystal Ball Nebula, for example, has an estimated temperature of 15,000 K.

Herschel found this object fascinating, amazed by its faintly illuminated shell. Prior to its discovery, he believed that nebulae were collections of stars that were too far away to individually resolve. The distinct bright point at the heart of the gaseous shell shattered this theory. He wrote in 1791, “Our judgment I may venture to say, will be, that the nebulosity about the star is not of a starry nature.” He believed the illumination of the Crystal Ball Nebula came from a single star, not a far-off grouping.

While it may appear in this image as if there is a single shining light source at the heart of the Crystal Ball Nebula, as Herschel saw, it actually contains two stars. These two stars orbit each other with a period of around nine years — the longest known for any binary pair within a planetary nebula. Scientists believe that one of these stars, which was once several times more massive than our Sun, released its outer layers while in the throes of death. As the progenitor star and its binary companion orbit each other, they mold the expanding shell of gas with their strong, asymmetrical winds, forming the lumpy layers we see today.

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

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More information

This image was produced by NSF NOIRLab’s Communication, Education & Engagement team, as part of the NOIRLab Legacy Imaging Program.

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.

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Links

• Explore the Crystal Ball Nebula in more detail
• Photos of the Gemini North telescope
• Videos of the Gemini North telescope
• Check out other NOIRLab Photo Releases

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Contacts:

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

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Playing Pool with Planets

An artist's impression of 10 hot Jupiters, one of the populations of Jupiter-sized planets.
Credit: ESA/Hubble & NASA; CC BY 4.0

An artist’s depiction of a hot Jupiter. These planets orbit extremely close to their host stars, but likely got to their locations by scattering inward from more distant orbits.  Credit: NASA/JPL-Caltech

A schematic showing where different planets ended up as a function of where they scattered from during their evolution.
Credit:: Esposito et al. 2026

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Each Jupiter-size planet in the galaxy falls into one of three distinct categories: hot, warm, or cold. A new study suggests that despite the apparent differences between these populations, they may have all formed from the same underlying dynamical process: a game of pool played at planetary scales.

A Diversity of Jupiters

Though our solar system has only one Jupiter-size planet, elsewhere in the galaxy we have found three different species of these massive gas giants. Cold Jupiters closely resemble their namesake and orbit far from their host stars; hot Jupiters are the opposite and are found whipping around their stars on extremely close-in orbits. In between these are the warm Jupiters, which tend to orbit in the intermediate space between 0.1 and 1.0 au.

Though these three populations are defined by their orbital distances, they differ from each other in other ways as well. For example, hot Jupiters almost never have nearby companions; if there are any other planets circling the same star, they’re usually far-out cold Jupiters. They can also orbit in pretty much any direction, including opposite the direction of their star’s spin, and are usually on perfectly circular orbits. In contrast, warm Jupiters often have friends nearby, are much more aligned with their stars’ spins, and can have modest eccentricities.

Given these differences, it’s often thought that each of these populations arrived at its current location through different dynamical processes and that the history of the warm Jupiters is likely quite different from the history of the hot Jupiters. However, a new study led by Julia Esposito (Georgia Institute of Technology) has proposed an alternative view. Maybe these populations, though they appear different now, were all created by the same process: planet–planet scattering.

Virtual Planetary Billiards

Esposito and collaborators set up 1,500 virtual planetary systems with three massive planets each, then simulated how the orbits evolved before probing the final configurations. In crucial contrast to previous simulation studies, the team initialized their Jupiters across a range of different distances and included the effects of tides sapping energy from orbits of planets that got too close to their host stars.

At the end of the simulation, the team surveyed the digital carnage. Almost every virtual system ended with only two planets after either ejecting one away from the star or having two planets collide. But, remarkably, the remaining two-planet systems looked tantalizingly similar to what we actually observe, with a mix of hot, warm, and cold Jupiters. Even more exciting, the end populations were highly correlated to where the violent scattering event took place.

For example, the warm Jupiters were almost all produced by “warm scattering” simulations, where the scattering took place between 0.1 and 1.0 au. The planets that survived the simulations and ended up as warm Jupiters matched all of the properties of the real warm Jupiter population: they had nearby companions, were moderately eccentric, and were mostly aligned with their stars. The hot Jupiters, meanwhile, were almost all produced by “cold scattering” events where the flybys happened far from the star and resulted in one planet hurtling inwards. These also matched all of the observed properties of real hot Jupiters.

The researchers concluded that planet–planet scattering can produce both the warm and hot Jupiter populations so long as you let the planets scatter from a variety of different distances. This exciting theoretical insight, if correct, would mean that astronomers could stop searching for different pathways to create each population. Happily, this model also provides testable predictions, and the authors lay out how the theory could be supported or disproven with additional data. Through virtual experiments like these, astronomers continue to build up an understanding of how the wide range of planetary architectures observed across the galaxy came to be.

By Ben Cassese

Citation

“Unified Formation Channel of Hot and Warm Jupiters via Planet–Planet Scattering,” Julia Esposito et al 2026 ApJL 1003 L3. doi:10.3847/2041-8213/ae61b0

Source: American Astronomical Society/AAS-Nova

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