Wouldn’t a free-floating planet eventually cross paths with a star or even a black hole and start revolving around it? YinToronto, Ontario Free-floating planets (FFPs) or rogue planets are bodies that move through space by themselves, not locked into an orbit around a star. While some may have begun as typical planets flung out ofContinue reading "Why aren’t free-floating planets captured when they fly past stars?"
Beyond the solar system, the line between planet and star can get blurry. Astronomers call objects that fall between the size ranges of planets and stars substellar objects. One type of substellar object, called a brown dwarf, forms from collapsing gas clouds like a star, but is not quite massive enough to fuse hydrogen in its core. Some can briefly fuse a heavier form of hydrogen, known as deuterium, in their cores, though never enough to produce starlight. Others are small and cold enough to develop complex atmospheres.
Recently, astronomers discovered a new type of substellar object in a star-forming region of the Milky Way Galaxy called IC 348. Using observational data from the JWST’s Near InfraRed Spectrograph (JWST NIRSpec), they found objects 0.2% to 1.2% the mass of the Sun that float freely like stars but have carbon-containing molecules called hydrocarbons in their atmospheres. Because these objects are smaller than known brown dwarfs and have evidence of hydrocarbons, scientists refer to them as H-type objects.
To investigate what H-type objects are and where they fit within the spectrum of substellar objects, researchers Richard J. Parker and Catarina Alves de Oliveira analyzed survey data on stars and substellar objects in IC 348, then conducted follow-up simulations to uncover how H-type objects formed. The main question they asked was whether H-type objects form from collapsing gas clouds, like brown dwarfs and stars, or develop around host stars before being ejected and drifting freely through space, like planets.
First, they reviewed the observational records of IC 348 obtained with the JWST NIRSpec and the near-IR spectrograph SpeX at the NASA Infrared Telescope Facility. IC 348 has 495 stars and brown dwarfs combined, as well as 9 H-type objects. Estimates for the age of this star-forming region range from either 1 to 3 million years or 5 to 6 million years, depending on how different teams calculated it. From there, Parker and Alves de Oliveira compared where the stars, brown dwarfs, and H-type objects were located within the cluster. They found no unique spatial distribution among the 3 types of objects.
Then, the team simulated the evolution of IC 348 over 10 million years to determine which initial conditions would result in a spatial distribution closest to the survey data. They simulated an initial giant gas cloud and used a mathematical function to distribute its mass among the 495 constituent objects. The researchers then placed a Jupiter-sized planet around each simulated star that was approximately the Sun’s mass to determine whether they could grow and escape their home star and become H-type objects. They also repeated the simulations by placing the Jupiter-sized planets at distances from the Sun similar to those of Earth, Jupiter, and Neptune, and varied the sizes and star densities of the simulated IC 348 regions.
They found that if Jupiter-sized planets orbited their stars at roughly Jupiter’s distance from the Sun, then 5 to 15 of them could escape their stars in a region like IC 348, which would roughly match the number of known H-type objects. However, the escaped planets were distinctly more spread-out than the observed H-type objects, which share a similar spatial distribution with the cluster’s stars and brown dwarfs. Since the simulations did not match the observed distribution, the researchers suggested that these H-type objects are likely a new sub-category of very small brown dwarfs rather than escaped planets.
Although this study favors a brown dwarf origin for H-type objects, the exact details of how they formed remain up for debate. Astronomers still have multiple competing theories about how ordinary brown dwarfs form. Perhaps they are ejected from their gas cloud before fully forming, have their outer layers stripped by radiation from a nearby massive star, or simply form like stars on a slightly smaller scale. Regardless, future researchers will continue to explore this murky area of substellar astronomy.
Searching for Another Earth with the Nancy Grace Roman Space Telescope
In NASA’s mission fact sheet, Roman’s planners pose several questions. These include:
How common are solar systems like our own?
What kinds of planets exist in the cold, outer regions of planetary systems?
What determines the habitability of Earth-like worlds?
Although scientists have used several methods to detect exoplanets, including Earth-like planets, Roman will employ three. These include the transit method, microlensing, and direct imaging. NASA said the combination of approaches will allow mission scientists to conduct a “sweeping search expected to uncover around 100,000 new exoplanets — a staggering leap compared to the nearly 6,200 currently known.”
“It is hoped that Roman will discover thousands of new exoplanets and significantly expand our knowledge of the diversity of planetary systems in our Galaxy,” explained Associate Professor Edita Stonkutė, an astrophysicist at Vilnius University unconnected to the Roman team, in a statement emailed to The Debrief.
Microlensing Can Reveal Earthlike Planets Orbiting Sunlike Stars
Most exoplanets have been detected by the dimming of their host star when they transit between it and Earth, giving the transit method its name. Roman plans to use that same method for most of its larger planetary detections. However, among the expected tens of thousands of transit-method detections, mission planners expect a small but sizeable percentage to come from microlensing.
NASA said the “light-bending” microlensing phenomenon occurs when two distant stars “align closely from our vantage point.” Due to the strength of the nearer star’s gravity, the light from the more distant one is “warped” around the nearer one, essentially focusing it very briefly for a distant observer.
“If the alignment is especially close, the nearer star acts like a cosmic lens, focusing and magnifying light from the background star.” Professor Stonkutė explained. “By analysing these changes, astronomers can determine that the planet exists and estimate its mass and orbital characteristics.”
Critically, Professor Stonkutė also noted that microlensing can occur with objects other than stars, including exoplanets.
“This is Precisely Where Roman Has the Edge”
Using its Wide-Field Array, Roman will monitor hundreds of millions of stars. NASA said the observatory will monitor these target stars for “tiny surges in starlight” that typically signal a microlensing event.
Although the transit method is employed to detect larger exoplanets, NASA noted that microlensing “specializes in finding planets like those in our solar system.” The space agency added that this includes “worlds as lightweight as Mars in their star’s habitable zone or farther out.”
A star’s habitable zone is typically defined as the orbital plane where an exoplanet could sustain liquid water on its surface, a key ingredient for life as we know it.
Professor Stonkutė described microlensing as “particularly valuable” since it can detect planets that are difficult to spot with other planet-hunting methods. The professor said this includes “small Earth-like planets located far from their star.” The Roman team hopes to find “more than 1,000 microlensing planets.”
The professor warned that “most microlensing events cannot be predicted in advance.” As a result, telescopes need to actively scan large areas of the sky to increase the chances of a microlensing detection
“This is precisely where Roman has the edge over other telescopes that have searched for exoplanets using different methods,” the professor added.
A “Stepping Stone” Toward NASA’s Habitable Worlds Observatory Concept
While Roman is tasked with directly imaging exoplanets, finding another Earth around a Sun-like star will still require an indirect detection, most likely from a microlensing event. However, the Roman team notes that their observatory “will provide a crucial stepping stone for NASA’s Habitable Worlds Observatory concept.”
According to the space agency, that “flagship” telescope, still awaiting final approval, “would be designed to photograph Earth-like planets for the first time ever.”
Roman may also be able to scan the atmospheres of planets detected with the transit method. The space agency said Roman “would also look for signs of life called biosignatures by measuring atmospheric gases like oxygen and ozone that could signal the presence of living things.”
Christopher Plain is a Science Fiction and Fantasy novelist and has spent the last six years as Associate News Editor and Head Science Writer at The Debrief. Follow and connect with him on X, learn about his books at plainfiction.com, or email him at christopher@thedebrief.org.
Artist’s concept of the Nancy Grace Roman Space Telescope (Credit: NASA).
Welcome to this special edition of The Intelligence Brief… This week, NASA is preparing to launch the Nancy Grace Roman Space Telescope, its next flagship space observatory and a mission poised to transform our understanding of distant worlds and some of the universe’s greatest mysteries. In our analysis, we’ll be looking at 1) how Roman’s powerful Wide Field and Coronagraph instruments will survey the cosmos on an unprecedented scale, 2) how the telescope could discover thousands of new exoplanets—including elusive rogue worlds—and directly image planets around other stars, 3) how Roman will survey more than a billion galaxies in search of new clues about dark matter and dark energy, and 4) why its combination of Hubble-like image quality and an enormously wider field of view could usher in a new era of astronomical discovery.
Quote of the Week
“We are poised at the brink of unfathomable scientific discovery.”
– Julie McEnery, Roman’s senior project scientist at NASA Goddard
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NASA’s Nancy Grace Roman Space Telescope Prepares for Lift-Off
On Sunday morning, NASA will set a new milestone with the launch of the Nancy Grace Roman Space Telescope, setting the course for discoveries that may include new insights into some of the universe’s greatest mysteries.
As NASA’s next flagship space observatory, this powerful new telescope is designed to discover thousands of distant worlds while also probing the lingering mysteries of dark matter and dark energy. Named after Nancy Grace Roman, NASA’s first chief of astronomy and an early advocate for the efforts that led to the launch of the Hubble Space Telescope, the new space observatory bearing her name is poised to offer one of the most detailed views of our universe ever captured.
Scheduled to lift off aboard a SpaceX Falcon Heavy rocket on August 30, 2026, at 7:26 a.m. EDT, the Roman telescope’s mission is comparable in ambition to those of the Hubble and James Webb Space Telescopes, but also very different in many respects. Here’s a look at what to know about this historic mission, what it may help researchers uncover, and why it could set the pace for a range of important scientific advancements in the coming years.
Roman’s Historic Mission to Observe the Cosmos
At the heart of its mission, Roman will offer astronomers a remarkably wide view of the cosmos. Surveying immense portions of the sky, the powerful instruments on board the telescope will capture high-resolution imagery comparable to Hubble at certain optical and infrared wavelengths—imagery that could dramatically reshape scientists’ understanding of both planets and the universe they inhabit.
In terms of the technologies it will carry with it into space, Nancy Grace Roman Space Telescope will rely on two primary instruments: its Wide Field Instrument (WFI) and Coronagraph Instrument. The WFI is equipped with a 300-megapixel near-infrared camera enabling wide-area imaging and spectroscopy, allowing Roman to conduct large-scale surveys with great precision and sensitivity—all of which make it ideal for use in the hunt for dark energy, exoplanets, and other hard-to-spot cosmic phenomena.
Meanwhile, Roman’s Coronagraph Instrument is designed specifically for imaging and studying exoplanets. Equipped for both imaging and spectroscopy, the coronagraph will suppress the overwhelming glare of distant stars, potentially making much fainter planets orbiting nearby visible. According to NASA, Roman’s powerful Coronagraph will be the first instrument deployed on a space observatory to leverage “numerically optimized, precision-fabricated coronagraph masks.”
By suppressing the overwhelming glare of distant stars so that much fainter planets around them become visible, Roman’s Coronagraph could achieve as much as 100 times the performance of existing facilities, offering a promising chance that some of the faintest planets in the cosmos—some as much as a billion times fainter than their host stars—could become visible.
With a little luck, Roman could also break new ground with the first direct imagery of an exoplanet possessing rings. Going beyond its immediate discoveries, the coronagraph will also demonstrate technologies that could eventually be incorporated into future observatories, including NASA’s proposed Habitable Worlds Observatory.
A New Era of Planet Hunting
Presently, astronomers have confirmed roughly 6,000 planets beyond our Solar System. However, once Roman’s mission gets underway, that number could see a dramatic increase.
One of the ways it will achieve such landmark detections will be with the help of gravitational microlensing, which relies on detecting how the gravity of a foreground object can magnify light from a source much farther away. Using microlensing alone, there is a good chance Roman may discover several hundred—but more likely thousands—of planets, which may include worlds small enough that they have eluded previous detection using existing methods.
Along with the planets it discovers, astronomers anticipate that Roman will also find several new additions to the growing catalog of “rogue planets,” mysterious planetary bodies that wander through the cosmos without orbiting a star.
Additionally, NASA says that anywhere from 60,000 to 200,000 additional candidate planets could be revealed through transit observations, though only a fraction of these are expected to be confirmed through additional observations.
Mapping the Dark Universe
Arguably, one of the most significant components of Roman’s mission involves its study of the unseen side of the cosmos: the mysterious phenomena known as dark energy and dark matter.
In search of answers to such mysteries, Roman will soon begin scanning more than a billion galaxies as it maps the structure and evolution of the universe throughout cosmic history, providing data that will at the very least help researchers narrow down the most promising interpretations among a range of competing explanations for dark energy.
Simultaneously, the telescope will probe dark matter, the unseen material whose gravitational effects are currently needed to explain phenomena in our universe that include the motions of galaxies, as well as the evolution of some of the largest structures in the cosmos.
Hubble’s Vision, But at Far Greater Scale
In many ways, what Roman is expected to achieve will be comparable to its predecessor, the Hubble Space Telescope, although at a far greater scale.
At some wavelengths, Roman will be capable of producing images that approach the clarity of Hubble’s iconic views of our universe, all while capturing as much as 100 times more of the sky with each observation. By capturing more of the sky with each image it produces, Roman’s efforts to map the universe could occur at a remarkable pace—perhaps a thousand times faster than those of its predecessor.
A Historic Mission Lifts Off This Sunday
If all goes according to plan, Roman will be launched aboard a SpaceX Falcon Heavy rocket at 7:26 a.m. EDT this Sunday, Aug. 30. NASA will begin live coverage of Roman’s launch on Sunday at 6:20 a.m. Eastern Time, and you can follow the updates online with NASA’s free streaming platforms.
Once it lifts off, Roman will be carried 930,000 miles from Earth to the Sun-Earth Lagrange Point 2 region, which is the same location where the James Webb Space Telescope is currently operating. After it reaches orbit, for the next 90 days, Roman will undergo commissioning, after which science operations are expected to begin sometime in early 2027.
The observatory’s primary mission will last five years, although Roman could potentially remain operational for more than a decade, offering astronomers an unprecedented look at our universe and possibly a few answers to some of the most baffling questions about our universe.
New research suggests that the circumplanetary disk surrounding the exoplanet PDS 70c contains a ring of dense dust, and the conditions within this ring may allow baby moons to form.
The young star PDS 70 has become famous for its protoplanetary disk and its two growing giant planets, PDS 70b and PDS 70c. At least one of these planets is surrounded by a disk of its own; in 2019, researchers using the Atacama Large Millimeter/submillimeter Array (ALMA) reported the first-ever observation of a circumplanetary disk around PDS 70c, and later observations with ALMA brought clearer views of this disk.
There’s still debate over the exact source of the emission detected by ALMA. Does this emission come from dust, and if so, how is the dust distributed? Is the disk optically thick or optically thin? Does the emission even come from dust, or could it instead be free–free emission from unbound electrons navigating a charged-particle maze?
Dust Diagnosis
Yuhito Shibaike (Kagoshima University) and collaborators recently examined the hypothesis that the emission from PDS 70c’s circumplanetary disk arises from dust distributed in an optically thick ring. To test this hypothesis, the team explored two possible dust distributions, which they call “drift” and “ring.” In the drift model, dust grains within the circumplanetary disk migrate inward toward the planet, leaving much of the disk optically thin. Modeling suggests that this migration is typical in protoplanetary disks, and it might be common in circumplanetary disks as well.
Dust and gas surface density for the modeled disks in the drift (orange) and ring (blue) models. Click to enlarge. [Adapted from Shibaike et al. 2026]
In the ring model, the dust grains are concentrated within an optically thick ring at a certain distance from the planet. Simulations suggest that the formation of this type of dust ring is feasible, arising from a localized increase in gas density, outflows, or other causes.
Shibaike and coauthors found that the ring model naturally reproduced the observed spectral energy distribution for a range of reasonable parameters. The drift model, on the other hand, required an unrealistically high dust-to-gas ratio for the material accreted onto the circumplanetary disk from the parent protoplanetary disk to reproduce the observed spectral index.
Future Prospects and Moon-Making Possibilities
Comparison of ALMA observations (colored symbols) and model predictions (colored lines) from the drift (orange) and ring (blue) models. Click to enlarge. [Adapted from Shibaike et al. 2026]
This work demonstrated the feasibility of the dust-ring model, but it didn’t rule out a contribution due to free–free emission from unbound electrons, which has also been proposed to explain the disk’s appearance. The team noted that distinguishing between thermal dust emission and free–free emission is challenging with existing data, as the two sources produce spectral energy distributions with similar shapes.
Luckily, this likely won’t remain a mystery forever: the next-generation Very Large Array, which is anticipated to begin full science operations in the mid-2030s, should be able to resolve the location of the dust within the circumplanetary disk and illuminate the source of emission.
Finally, if the dust surrounding PDS 70c is concentrated within a ring, what does that mean for the possibility of moons forming within the disk? Shibaike and collaborators found that the conditions within the ring likely satisfy the requirements of both the streaming instability and the gravitational instability, which are required for dust grains to clump together and form the rocky building blocks of baby moons. Perhaps the PDS 70 system will one day be the site of not only a circumplanetary disk, but an exomoon as well!
Citation
“Interpreting ALMA Multiwavelength Continuum Observations of PDS 70 c: An Optically Thick Dust Ring in the Circumplanetary Disk,” Yuhito Shibaike et al 2026 ApJL1006 L26. doi:10.3847/2041-8213/ae86f5
Ultra-hot Jupiter WASP-121b is once again puzzling astronomers. New JWST observations have revealed aspects of this superheated planet’s atmosphere that models cannot yet explain.
An Extreme Planet
Among the more than 6,000 known exoplanets, there are many types of worlds that aren’t represented in our solar system. The most exotic and unfamiliar planets might be the ultra-hot Jupiters: giant planets nestled so close to their host stars that they are tidally locked, with temperatures on their permanently starlit sides climbing to thousands of degrees.
WASP-121b, which circles its F-dwarf host star every 30.5 hours, is one of the best-studied ultra-hot Jupiters. Previous work has started to reveal the complexity of its atmosphere, and now, data from JWST have opened a new window onto WASP-121b’s behavior.
New View from JWST
A representation of an exoplanet’s phase curve. Click to enlarge. [ESA]
To learn more about WASP-121b’s atmosphere, Robert C. Frazier (University of Michigan) and collaborators analyzed JWST Near Infrared Imager and Slitless Spectrograph (NIRISS) observations covering more than one full orbit of the planet. These observations allowed them to construct the system’s phase curve, which describes the total amount of emitted and reflected light from the planet and its host star over an entire orbit.
The team used two 3D general circulation models to predict the planet’s atmospheric structure and extract synthetic spectra and phase curves to compare against the JWST observations. Using nine model configurations in total, the team varied several inputs, including sources of atmospheric opacity, sources of atmospheric drag, and assumptions about whether clouds are able to form on the planet’s cooler nightside.
Left with a Mystery
Frazier and collaborators found two aspects of WASP-121b’s phase curve that their models couldn’t explain: the planet emits less light overall than predicted, and the location of its phase-curve offset changes with wavelength.
Modeled phase curves, shown as the flux of the planet divided by the flux of the star, for WASP-121b (colored solid and dotted lines) compared to the best fit to the JWST observations (black line). Click to enlarge. [Frazier et al. 2026]
The models predict, on average, 12–15% more emission from the planet than observed. This discrepancy might be traced back to how the planet’s radius is determined, which is a simple-sounding task that can be deceptively difficult; WASP-121b isn’t perfectly spherical, and its emitting area changes with wavelength, making it challenging to normalize the planet’s radius for use in models.
The phase-curve offset is the difference between a planet’s sub-stellar point (where the star is directly overhead) and the brightest point in the planet’s atmosphere. In general, some degree of offset is expected because planetary winds tend to whisk heat away from the sub-stellar point, placing the brightest point somewhere to the east (usually). For WASP-121b, the offset is unexpectedly small — suggesting a source of drag in the atmosphere that prevents winds from transporting heat away from the sub-stellar point — and it’s larger at shorter wavelengths. This wavelength dependence isn’t predicted by any of the models, and it’s not clear what causes it.
These results demonstrate something remarkable: that our observations of a planet nearly 900 light-years away have become so precise that they’re pushing our already complex models to include more physics — an exceptionally exciting motivation for model improvement!
Citation
“The Days Drag On on WASP-121 b: Interpreting Its NIRISS Spectroscopic Phase Curve with General Circulation Models,” Robert C. Frazier et al 2026 ApJ1004 102. doi:10.3847/1538-4357/ae69ca
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