Astronomy

This year marked the end of a decades-long wait for astronomers. The James Webb Space Telescope is finally in action.

The telescope, which launched in December 2021, released its first science data in July (SN: 8/13/22, p. 30) and immediately began surpassing astronomers’ expectations.

“We’ve realized that James Webb is 10 times more sensitive than we predicted” for some kinds of observations, says astronomer Sasha Hinkley of the University of Exeter in England. His team released in September the telescope’s first direct image of an exoplanet (SN: 9/24/22, p. 6). He credits “the people who worked so hard to get this right, to launch something the size of a tennis court into space on a rocket and get this sensitive machinery to work perfectly. And I feel incredibly lucky to be the beneficiary of this.”

The telescope, also known as JWST, was designed to see further back into the history of the cosmos than ever before (SN: 10/9/21 & 10/23/21, p. 26). It’s bigger and more sensitive than its predecessor, the Hubble Space Telescope. And because it looks in much longer wavelengths of light, JWST can observe distant and veiled objects that were previously hidden.

JWST spent its first several months collecting “early-release” science data, observations that test the different ways the telescope can see. “It is a very, very new instrument,” says Lamiya Mowla, an astronomer at the University of Toronto. “It will take some time before we can characterize all the different observation modes of all four instruments that are on board.”

That need for testing plus the excitement has led to some confusion for astronomers in these heady early days. Data from the telescope had been in such high demand that the operators hadn’t yet calibrated all the detectors before releasing data. The JWST team is providing calibration information so researchers can properly analyze the data. “We knew calibration issues were going to happen,” Mowla says.

The raw numbers that scientists have pulled out of some of the initial images may end up being revised slightly. But the pictures themselves are real and reliable, even though it takes some artistry to translate the telescope’s infrared data into colorful visible light (SN: 3/17/18, p. 4).

The stunning photos that follow are a few of the early greatest hits from the shiny new observatory.

Deep space

NASA, ESA, CSA, STScI

JWST has captured the deepest views yet of the universe (above). Galaxy cluster SMACS 0723 (bluer galaxies) is 4.6 billion light-years from Earth. It acts as a giant cosmic lens, letting JWST zoom in on thousands of even more distant galaxies that shone 13 billion years ago (the redder, more stretched galaxies). The far-off galaxies look different in the mid-infrared light (above left) captured by the telescope’s MIRI instrument than they do in the near-infrared light (above right) captured by NIRCam. The first tracks dust; the second, starlight. Early galaxies have stars but very little dust.

Rings around Neptune

NASA, ESA, CSA, STSCI; IMAGE PROCESSING: JOSEPH DEPASQUALE/STSCI, NAOMI ROWE-GURNEY/NASA GODDARD SPACE FLIGHT CENTER

JWST was built to peer over vast cosmic distances, but it also provides new glimpses at our solar system neighbors. This pic of Neptune was the first close look at its delicate-looking rings in over 30 years (SN: 11/5/22, p. 5).

Under pressure

NASA, ESA, CSA, STScI, JPL-Caltech/NASA

The rings in this astonishing image are not an optical illusion. They’re made of dust, and a new ring is added every eight years when the two stars in the center of the image come close to each other. One of the stars is a Wolf-Rayet star, which is in the final stages of its life and puffing out dust. The cyclical dusty eruptions allowed scientists to directly measure for the first time how pressure from starlight pushes dust around (SN: 11/19/22, p. 6).

Galaxy hit-and-run

NASA James Webb Space Telescope/Flickr (CC BY 2.0)

With JWST’s unprecedented sensitivity, astronomers plan to compare the earliest galaxies with more modern galaxies to figure out how galaxies grow and evolve. This galactic smashup, whose main remnant is known as the Cartwheel galaxy, shows a step in that epic process (SN Online: 8/3/22). The large central galaxy (right in the above composite) has been pierced through the middle by a smaller one that fled the scene (not in view). The Hubble Space Telescope previously snapped a visible light image of the scene (top half). But with its infrared eyes, JWST has revealed much more structure and complexity in the galaxy’s interior (bottom half).

Exoplanet portrait

NASA, ESA, CSA, Aarynn Carter/UCSC, The ERS 1386 Team, Alyssa Pagan/STSCI

The gas giant HIP 65426b was the first exoplanet to have its portrait taken by JWST (each inset shows the planet in a different wavelength of light; the star symbol shows the location of the planet’s parent star). This image, released by astronomer Sasha Hinkley and colleagues, doesn’t look like much compared with some of the other spectacular space vistas from JWST. But it will give clues to what the planet’s atmosphere is made of and shows the telescope’s potential for doing more of this sort of work on even smaller, rocky exoplanets (SN: 9/24/22, p. 6).

Shake the dust off

NASA, ESA, CSA, STScI, Hubble Heritage Project/STScI/AURA; Image Processing: Joseph DePasquale, Anton M. Koekemoer and Alyssa Pagan/STScI

Another classic Hubble image updated by JWST is the Pillars of Creation. When Hubble viewed this star-forming region in visible light, it was shrouded by dust (above left). JWST’s infrared vision reveals sparkling newborn stars (above right). More

The infant universe transforms from a featureless landscape to an intricate web in a new supercomputer simulation of the cosmos’s formative years.

An animation from the simulation shows our universe changing from a smooth, cold gas cloud to the lumpy scattering of galaxies and stars that we see today. It’s the most complete, detailed and accurate reproduction of the universe’s evolution yet produced, researchers report in the November Monthly Notices of the Royal Astronomical Society.

This virtual glimpse into the cosmos’s past is the result of CoDaIII, the third iteration of the Cosmic Dawn Project, which traces the history of the universe, beginning with the “cosmic dark ages” about 10 million years after the Big Bang. At that point, hot gas produced at the very beginning of time, about 13.8 billion years ago, had cooled to a featureless cloud devoid of light, says astronomer Paul Shapiro of the University of Texas at Austin.

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The universe was a cold, dark place 10 million years after the Big Bang. Hydrogen gas began to clump together 100 million years later, forming dense regions (white) that gave birth to the first stars and galaxies, as seen in this animation from a new simulation of the early universe. Light radiating from the stars (blue) heated the gas around the galaxies as matter collected in a weblike arrangement. The pink bursts are high-temperature regions that appeared as some stars exploded. The galaxies and stars we see today lie along the filaments that resulted from the complicated interplay between matter and starlight as the universe evolved.

Roughly 100 million years later, tiny ripples in the gas left over from the Big Bang caused the gases to clump together (SN: 2/19/15). This led to long, threadlike strands that formed a web of matter where galaxies and stars were born. 

 As radiation from the early galaxies illuminated the universe, it ripped electrons from atoms in the once-cold gas clouds during a period called the epoch of reionization, which continued until about 700 million years after the Big Bang (SN: 2/6/17).

CoDaIII is the first simulation to fully account for the complicated interaction between radiation and the flow of matter in the universe, Shapiro says. It spans the time from the cosmic dark ages and through the next several billion years as the distribution of matter in the modern universe formed.

The animation from the simulation, Shapiro says, graphically shows how the structure of the early universe is “imprinted on the galaxies today, which remember their youth, or their birth or their ancestors from the epoch of reionization.” More

For the first time, astronomers have observed how certain supermassive black holes launch jets of high-energy particles into space — and the process is shocking.

Shock waves propagating along the jet of one such blazar contort magnetic fields that accelerate escaping particles to nearly the speed of light, astronomers report November 23 in Nature. Studying such extreme acceleration can help probe fundamental physics questions that can’t be studied any other way.

Blazars are active black holes that shoot jets of high-energy particles toward Earth, making them appear as bright spots from millions or even billions of light-years away (SN: 7/14/15). Astronomers knew that the jets’ extreme speeds and tight columnated beams had something to do with the shape of magnetic fields around black holes, but the details were fuzzy.

Enter the Imaging X-Ray Polarimetry Explorer, or IXPE, an orbiting telescope launched in December 2021. Its mission is to measure X-ray polarization, or how X-ray light is oriented as it travels through space. While previous blazar observations of polarized radio waves and optical light probed parts of jets days to years after they’d been accelerated, polarized X-rays can see into a blazar’s active core (SN: 3/24/21).

“In X-rays, you’re really looking at the heart of the particle acceleration,” says astrophysicist Yannis Liodakis of the University of Turku in Finland. “You’re really looking at the region where everything happens.”

In March 2022, IPXE looked at an especially bright blazar called Markarian 501, located about 450 million light-years from Earth.

Liodakis and colleagues had two main ideas for how magnetic fields might accelerate Markarian 501’s jet. Particles could be boosted by magnetic reconnection, where magnetic field lines break, reform and connect with other nearby lines. The same process accelerates plasma on the sun (SN: 11/14/19). If that was the particle acceleration engine, the polarization of light should be the same along the jet in all wavelengths, from radio waves to X-rays.

Another option is a shock wave shooting particles down the jet. At the site of the shock, the magnetic fields suddenly switch from turbulent to ordered. That switch could send particles zooming away, like water through the nozzle of a hose. As the particles leave the shock site, turbulence should take over again. If a shock was responsible for the acceleration, short wavelength X-rays should be more polarized than longer wavelength optical and radio light, as measured by other telescopes.

The IXPE spacecraft (illustrated) observed polarized X-rays come from a blazar and its jet. The inset illustrates how particles in the jet hit a shock wave (white) and get boosted to extreme speeds, emitting high-energy X-ray light. As they lose energy, the particles emit lower energy light in visible, infrared and radio wavelengths (purple and blue), and the jet becomes more turbulent.Pablo Garcia/MSFC/NASA

That’s exactly what the researchers saw, Liodakis says. “We got a clear result,” he says, that favors the shock wave explanation.

There is still work to do to figure out the details of how the particles flow, says astrophysicist James Webb of Florida International University in Miami. For one, it’s not clear what would produce the shock. But “this is a step in the right direction,” he says. “It’s like opening a new window and looking at the object freshly, and we now see things we hadn’t seen before. It’s very exciting.” More

The closest black hole yet found is just 1,560 light-years from Earth, a new study reports. The black hole, dubbed Gaia BH1, is about 10 times the mass of the sun and orbits a sunlike star.

Most known black holes steal and eat gas from massive companion stars. That gas forms a disk around the black hole and glows brightly in X-rays. But hungry black holes are not the most common ones in our galaxy. Far more numerous are the tranquil black holes that are not mid-meal, which astronomers have dreamed of finding for decades. Previous claims of finding such black holes have so far not held up (SN: 5/6/20; SN: 3/11/22).

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So astrophysicist Kareem El-Badry and colleagues turned to newly released data from the Gaia spacecraft, which precisely maps the positions of billions of stars (SN: 6/13/22). A star orbiting a black hole at a safe distance won’t get eaten, but it will be pulled back and forth by the black hole’s gravity. Astronomers can detect the star’s motion and deduce the black hole’s presence.

Out of hundreds of thousands of stars that looked like they were tugged by an unseen object, just one seemed like a good black hole candidate. Follow-up observations with other telescopes support the black hole idea, the team reports November 2 in Monthly Notices of the Royal Astronomical Society.

Gaia BH1 is the nearest black hole to Earth ever discovered — the next closest is around 3,200 light-years away. But it’s probably not the closest that exists, or even the closest we’ll ever find. Astronomers think there are about 100 million black holes in the Milky Way, but almost all of them are invisible. “They’re just isolated, so we can’t see them,” says El-Badry, of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass.

The next data release from Gaia is due out in 2025, and El-Badry expects it to bring more black hole bounty. “We think there are probably a lot that are closer,” he says. “Just finding one … suggests there are a bunch more to be found.” More

The brightest gamma-ray burst ever recorded recently lit up a distant galaxy — and astronomers have nicknamed it the BOAT, for Brightest of All Time.

“We use the boat emoji a lot when we’re talking about it” on the messaging app Slack, says astronomer Jillian Rastinejad of Northwestern University in Evanston, Ill.

Gamma-ray bursts are energetic explosions that go off when a massive star dies and leaves behind a black hole or neutron star (SN: 11/20/19; SN: 8/2/21). The collapse sets off jets of gamma rays zipping away from the poles of the former star. If those jets happen to be pointed right at Earth, astronomers can see them as a gamma-ray burst.

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This new burst, officially named GRB 221009A, was probably triggered by a supernova giving birth to a black hole in a galaxy about 2 billion light-years from Earth, researchers announced October 13. Astronomers think it released as much energy as roughly three suns converting all of their mass to pure energy.

NASA’s Neil Gehrels Swift Observatory, a gamma-ray telescope in space, automatically detected the blast October 9 around 10:15 a.m. EDT, and promptly alerted astronomers that something strange was happening.

“At the time, when it went off, it looked kind of weird to us,” says Penn State astrophysicist Jamie Kennea, who is the head of science operations for Swift. The blast’s position in the sky seemed to line up with the plane of the Milky Way. So at first Kennea and colleagues thought it was within our own galaxy, and so unlikely to be something as dramatically energetic as a gamma-ray burst. If a burst like this went off inside the Milky Way, it would be visible to the naked eye, which wasn’t the case.

But soon Kennea learned that NASA’s Fermi Gamma-ray Space Telescope had also seen the flash — and it was one of the brightest things the telescope had ever seen. A fresh look at the Swift data convinced Kennea and colleagues that the flash was the brightest gamma-ray burst seen in the 50 years of observing these rare explosions.

“It’s quite exceptional,” Kennea says. “It stands head and shoulders above the rest.”

This series of visible-light images from NASA’s Swift telescope’s ultraviolet/optical instrument shows that the bright glow of the gamma-ray burst GRB 221009A (yellow circle) faded over about 10 hours.Swift/NASA, B. Cenko

After confirmation of the burst’s BOAT bonafides — a term coined by Rastinejad’s adviser, Northwestern astronomer Wen-fai Fong — other astronomers rushed to get a look. Within days, scientists around the world got a glimpse of the blast with telescopes in space and on the ground, in nearly every type of light. Even some radio telescopes typically used as lightning detectors saw a sudden disturbance associated with GRB 221009A, suggesting that the burst stripped electrons from atoms in Earth’s atmosphere.

In the hours and days after the initial explosion, the burst subsided and gave way to a still relatively bright afterglow. Eventually, astronomers expect to see it fade even more, replaced by glowing ripples of material in the supernova remnant.

The extreme brightness was probably at least partially due to GRB 221009A’s relative proximity, Kennea says. A couple billion light-years might seem far, but the average gamma-ray burst is more like 10 billion light-years away. It probably was also just intrinsically bright, though there hasn’t been time to figure out why.

Studying the blast as it changes is “probably going to challenge some of our assumptions of how gamma-ray bursts work,” Kennea says. “I think people who are gamma-ray burst theorists are going to be inundated with so much data that this is going to change theories that they thought were pretty solid.”

GRB 221009A will move behind the sun from Earth’s perspective starting in late November, shielding it temporarily from view. But because its glow is still so bright now, astronomers are hopeful that they’ll still be able to see it when it becomes visible again in February.

“I’m so excited for a few months from now when we have all the beautiful data,” Rastinejad says. More

Good news for late bloomers: Planets may have millions of years more time to arise around most stars than previously thought.

Planet-making disks around young stars typically last for 5 million to 10 million years, researchers report in a study posted October 6 at arXiv.org. That disk lifetime, based on a survey of nearby young star clusters, is a good deal longer than the previous estimate of 1 million to 3 million years.

“One to three megayears is a really strong constraint for forming planets,” says astrophysicist Susanne Pfalzner of Forschungszentrum Jülich in Germany. “Finding that we have a lot of time just relaxes everything” for building planets around young stars.

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Planets large and small develop in the disks of gas and dust that swirl around young stars (SN: 5/20/20). Once a disk vanishes, it’s too late to make any more new worlds.

Past studies have estimated disk lifetimes by looking at the fraction of young stars of different ages that still have disks — in particular, by observing star clusters with known ages. But Pfalzner and her colleagues discovered something odd: The farther a star cluster is from Earth, the shorter the estimated disk lifetime. That made no sense, she says, because why should the lifetime of a protoplanetary disk depend on how far it is from us?

The answer is quite simple: It doesn’t. But in clusters that are farther away, it’s harder to see most stars. “When you look at larger distances, you see higher-mass stars,” Pfalzner says, because those stars are brighter and easier to see. “You basically don’t see the low-mass stars.” But the lowest-mass stars constitute the vast majority. These stars, orange and red dwarfs, are cooler, smaller and fainter than the sun.

So Pfalzner and her colleagues examined only the nearest young star clusters, those within 650 light-years of Earth, and found that the fraction of stars with planet-making disks was much higher than that reported in previous studies. This analysis showed that “the low-mass stars have much longer disk lifetimes, between 5 and 10 megayears,” than astronomers realized, she says. In contrast, disks around higher-mass stars are known to disperse faster than this, perhaps because their suns’ brighter light pushes the gas and dust away more quickly.

“I wouldn’t say that this is definite proof” for such long disk lifetimes around orange and red dwarfs, says Álvaro Ribas, an astronomer at the University of Cambridge who was not involved with the work. “But it’s quite convincing.”

To bolster the result, he’d like to see observations of more distant star clusters — perhaps with the James Webb Space Telescope — to determine the fraction of the faintest stars that have preserved their planet-making disks between 5 million and 20 million years (SN: 10/11/22).

If the disks around the lowest mass stars do indeed have long lifetimes, that may explain a difference between our solar system and those of most red dwarfs, Pfalzner says. The latter often lack gas giants like Jupiter and Saturn, which are about 10 times the diameter of Earth. Instead, those stars frequently have numerous ice giants like Uranus and Neptune, about four times the diameter of Earth. Perhaps Neptune-sized planets arise in larger numbers when a planet-making disk lasts longer, Pfalzner says, accounting for why these worlds tend to abound around smaller stars. More

A pair of stars in our galaxy is revealing how light pushes around matter. It’s the first time anyone has directly seen how the pressure of light from stars changes the flow of dust in space.

Such radiation pressure influences how dust clears from the regions near young stars and guides the formation of gas clouds around dying stars (SN: 9/22/20). The dust pattern surrounding a stellar pair 5,600 light-years away in the Cygnus constellation is providing a rare laboratory to observe the effect in action, astronomer Yinuo Han and colleagues report in the Oct. 13 Nature. 

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Astronomers have long known that the dust emerging from the star WR 140 and its companion is formed by gas from these two stars colliding and condensing into soot. But images of the pair taken over the course of 16 years show that the dust is accelerating as it travels away from the stars.

Dust initially departs the stars at about 6.5 million kilometers per hour, the researchers report, and over the course of a year accelerates to nearly 10 million km/h. At that speed, the dust could make the trip from our sun to Earth in a mere 15 hours.

The revelation came from comparing the positions of concentric dust shells year to year and deducing a speed. The researchers’ calculations show that the force accelerating the dust is the pressure exerted by light radiated from the stars, says Han, of the University of Cambridge. “Radiation pressure [becomes apparent] only when we put all the images next to each other.”  

Not only are those layers of dust feeling light’s push, they also extend out farther than any telescope could see — until this year. Images from the James Webb Space Telescope, or JWST, depict more of the dusty layers around WR 140 and its companion than ever seen before, Han and another team report October 12 in Nature Astronomy.

At first glance, the intricate patterns surrounding the stars resemble a gigantic spiderweb. But the researchers’ analysis reveals that they are actually enormous, expanding, cone-shaped dust shells. They’re nested inside each other, with a new one forming every eight years as the stars complete another journey around their orbits. In the new images, the shells look like sections of rings because we observe them from the side, Han says.  

A computer simulation that takes radiation pressure from starlight into account shows how a dust plume (expanding arc and line) emerges from a pair of orbiting stars (not visible).Y. Han/Univ. of Cambridge

The patterns don’t completely surround the stars because the distance between the stars changes as they orbit one another. When the stars are far apart, the density of the colliding gas is too low to condense to dust — an effect the researchers expected. 

What surprised them is that the gas doesn’t condense well when the stars are closest together either. That suggests there’s a “Goldilocks zone” for dust formation: Dust forms only when the separation between the stars is just right, creating a series of concentric dust shells rippling away from the duo.

“Their Goldilocks zone is a new idea,” says astrophysicist Andy Pollock of the University of Sheffield in England, who was not part of either study. “A similar sort of thing happens in my field of X-rays.”

In his work, Pollock has observed that WR 140 and its partner emit more X-rays as the stars approach each other, but then fewer as they get very close together, suggesting there’s a Goldilocks zone for X-rays coming from the stars as well. “It would be interesting to see if there’s any connection” between the two types of Goldilocks zones, he says. “All of this must somehow fit together.” More