James Webb captured two protoplanetary disks: a look into the early stages of the formation of new planets
NASA, ESA, and CSA have released a new edition of the James Webb telescope’s monthly image, and this time the focus is not on distant galaxies or spectacular nebulae, but on two very young stellar systems in which the conditions for planet formation are still taking shape. These are the protoplanetary disks Tau 042021 and Oph 163131, objects located relatively nearby in astronomical terms, at about 450 and 480 light-years from Earth, respectively. The published composite, presented on April 3, 2026, combines observations from the James Webb telescope with earlier data from the Hubble telescope, and for Oph 163131 also with radio observations from the ALMA system, giving astronomers a more detailed insight into the distribution of dust particles, gas, and structures within the disks themselves.
The special value of this release lies not only in the impressive depiction of two young systems, but also in the fact that both disks are oriented almost edge-on toward Earth. Such a position allows astronomers to have the intense light of the young star at the center largely blocked by the disk itself, so instruments can more clearly record the scattered light and layers of fine dust above and below the plane of the disk. This is precisely crucial for understanding the processes that precede planet formation, because the distribution of material in these zones determines where dust grains can collide, stick together, and gradually grow into larger bodies.
Why protoplanetary disks are important for understanding the formation of planetary systems
Protoplanetary disks form after a star is born. When a clump of gas and dust collapses within a giant molecular cloud, a young star forms at the center, while the remaining material continues to orbit it in the form of a dense, flattened disk. In these disks, the long process of particle growth begins: from very fine cosmic dust, through ever larger clumps, all the way to planetesimals, bodies considered the building blocks of planets. Some of the material never grows into planets, but remains in the form of asteroids, comets, and other smaller bodies, while part of the gas is gradually blown away over time by the radiation and activity of the young star.
That is exactly why astronomers observe such objects with great interest. By looking at other systems in their early stage, they are trying to reconstruct what was happening in our own Solar System about 4.5 billion years ago. Today’s arrangement of planets, gas giants, rocky worlds, asteroids, and comets is actually the final result of processes that must once have looked similar to what is now seen around young stars in the constellations of Taurus and Ophiuchus.
Two objects, two similar geometries, but also important details for science
Tau 042021, also known by the catalog designation 2MASS J04202144+2813491, is located in the star-forming region in the constellation of Taurus. Oph 163131, or 2MASS J16313124-2426281, is located in the constellation of Ophiuchus. At first glance, both structures resemble colored space spinning tops or butterfly-like scatterings of light, but behind that visual impressiveness lies very precise scientific information. Since we observe them almost from the edge, the disks appear as a darker horizontal band, while illuminated clouds of fine dust reflecting the light of the central star appear above and below it.
Such a perspective is especially useful because it allows the study of the vertical structure of the disk. Scientists are interested not only in how much material orbits the young star, but also in how that material is distributed in height and depth. If larger dust grains settle over time toward the central plane of the disk, the density of material there increases, and with it the possibility that more efficient gathering of particles into larger bodies can begin. Such “settling” or deposition of dust is considered one of the key steps toward the formation of planetesimals and later planets.
What James Webb showed, and what Hubble and ALMA added
The published images are composed of data from the NIRCam and MIRI instruments on the James Webb telescope, as part of observing program number 2562, led by astronomers François Ménard and Karl Stapelfeldt. This program was designed specifically to study disks that we see edge-on from Earth, because such objects offer a rare opportunity to simultaneously track surface layers of scattered light, deeper infrared signals, and colder, denser layers in the central plane revealed by radio observations.
Webb is especially important because it operates in the infrared region of the spectrum. NIRCam records near-infrared radiation, and MIRI mid-infrared, so together they make it possible to track different sizes of dust grains and chemical traces within the disk. According to the explanation from the ESA/Webb release, the red, orange, and green tones in the composite images point to different sizes of dust particles and to the presence of molecules and compounds such as molecular hydrogen, carbon monoxide, and polycyclic aromatic hydrocarbons. In other words, this is not just an aesthetically processed image, but a map of the physical conditions inside young systems.
Hubble data were added in order to show the visible light reflected from the central star by very tiny dust grains. This creates a bridge between the optical and infrared views of the same object. In the case of the Oph 163131 system, observations from the ALMA interferometer, which operates at millimeter and submillimeter wavelengths, were also included in the analysis. Unlike Hubble and Webb, which are especially good at seeing very fine dust, ALMA detects larger grains, approximately millimeter-sized, concentrated closer to the central plane of the disk. These larger grains are precisely one of the important prerequisites for the further growth of material into larger, more compact bodies.
Oph 163131 and the trace that could point to planet formation
One of the most interesting details from the new release concerns the Oph 163131 system. ALMA data in its inner part show a gap, that is, an emptiness in the distribution of dust. Astronomers do not categorically claim that a planet has already been confirmed there, but they state that such a structure could be a sign that a young planetary body is forming in the disk, whose gravity removes or redistributes the surrounding material. In astronomy, precisely such restrained wording is important: a gap in the disk can be a very strong indicator of changes accompanying planet formation, but additional observations and modeling are usually required for final confirmation.
Earlier studies based on ALMA had already indicated that Oph 163131 is a strongly “settled” disk, meaning that larger dust grains are efficiently concentrated in a thin, dense layer along the central plane. Such a state is of particular interest to researchers because higher density in that narrow belt can accelerate the processes of grain growth and the creation of planetesimals. The new Webb composite is therefore not an isolated visual curiosity, but part of a broader picture that has been built over the years by combining observations from different telescopes and at different wavelengths.
Tau 042021 and why it is important for studying the vertical mixing of dust
Tau 042021 has also been the subject of more detailed analyses in recent years. Earlier ALMA observations showed that this disk has pronounced signs of vertical separation of particles of different sizes, meaning that larger grains are distributed differently from smaller ones. This is precisely one of the key problems in the physics of protoplanetary disks: how dust separates, settles, and moves within the disk before larger clumps form. James Webb program number 2562 was designed to connect optical images previously taken by Hubble, ALMA observations of colder and larger dust in the central plane, and the new infrared view that can “peer” between those layers.
For scientists, this means the possibility of empirically estimating for the first time with greater precision how the density and size of grains change with height in the disk. This is more than a technical detail. The models that try to explain how scattered dust can grow at all into bodies kilometers in size, that is, to the stage when gravity begins to play a significantly greater role in further growth, depend on it.
Why images like these have both scientific and public value
Releases like this regularly attract great public attention because of the unusual and attractive appearance of the images, but their scientific value is far deeper than mere visual impression. Edge-on protoplanetary disks are among the most valuable natural laboratories for studying the early stages of the formation of planetary systems. The usual “top-down” view often makes it difficult to separate the layers within the disk, while the side view allows more direct estimates of the thickness of the layers, the distribution of fine and coarser dust, and the relationships between illuminated surfaces and the darker central plane.
In addition, Webb confirms how important it is to connect multiple observatories. Hubble provides visible light and a long archive of observations, Webb offers exceptional sensitivity in the infrared region and the ability to penetrate through dust clouds, and ALMA reveals colder and coarser material that is crucial for the physical growth of future planets. Only when all these data are assembled together does a more complete picture emerge of what is happening in disks that are only a fraction of the age of a star’s lifetime.
That is precisely why the new image of the two disks is not just another visual curiosity from deep space. It shows what the stage looks like in which the material has not yet turned into finished planets, but the basic processes are already underway. In one case, a system can be seen in which the distribution of particles through multiple layers can be tracked, and in the other, an inner gap that could point to a very early sign of planet formation. For astronomy, this is a look back toward the conditions from which both Earth and the other worlds of the Solar System were formed, and for the wider public, a reminder that planet formation does not happen in a single dramatic moment, but in a long, complex, and still insufficiently clarified series of processes that leave recognizable traces in the dust and gas around young stars.
Sources:- ESA/Webb – official release “A pair of planet-forming discs”, with a description of the objects Tau 042021 and Oph 163131, the publication date, and an explanation of the display (link)- STScI – JWST program 2562 “Dust Settling and Grain Evolution in Edge-on Protoplanetary Disks”, with a summary of the scientific goals of the observations (link)- JPL/NASA Catalog of Circumstellar Disks – basic data and reference papers for the object Oph 163131 (link)- Science Explorer / A&A – summary of the paper on ALMA observations of edge-on protoplanetary disks, including Tau 042021 and the settling of larger grains (link)
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