New evidence has come to light showing that the mysterious 'little red dots' discovered in the early universe by the James Webb Space Telescope could evolve into the active centers of fully formed galaxies.

"Everything created in the early universe must evolve into something around us," said George Rieke of the University of Arizona in a statement. "We have had little idea of what little red dots become, but these results finally show us how to find their progeny."

Discovered by the James Webb Space Telescope (JWST) almost as soon as it became operational in 2022, little red dots have been a perplexing cosmological mystery. As their name suggests, they appear small, red and surprisingly bright. They are mostly found at redshift values suggesting they existed between 13.2 and 12.2 billion years ago. To shine so brightly at such great distances would usually imply these objects are quasars — which are luminous nuclei of galaxies powered by active supermassive black holes — but the light coming from little red dots is more like that of bloated stars. It looks to be mostly in infrared with some ultraviolet, and none of the X-rays that one would expect from an active black hole chomping down on material.

As such, researchers have come up with the hypothesis that little red dots are "black hole stars," or vast clouds of gas heated from within by a concealed but growing supermassive black hole.

However, the population of little red dots drops off a cliff at redshifts equating to less than 12 billion years ago. Where did they all go? There are two options. Either they all died off, or they developed into objects more familiar to us.

One recent hypothesis is that little red dots turned into large globular clusters. And now, an alternative possibility has come along.

A team led by Pierluigi Rinaldi, who was at the University of Arizona's Steward Observatory when conducting this research but is now at the Space Telescope Science Institute (STScI) in Baltimore, think it has identified a descendent of a little red dot. It appears to be in the form of a distant galaxy, catalogued as WISEA J123635.56+621424.2, which is found at a redshift of 2, meaning that we see it as it was 10.5 billion years ago.

The galaxy displays neat spiral arms around a red core. Rinaldi's team have nicknamed it the Saguaro, after a species of cactus native to the Sonoran desert in the United States' south-west, thanks to the galaxy's arms and how its core resembles the red fruit produced by the cactus.

Saguaro's core has all the hallmarks of a little red dot. It shines bright in infrared as seen by JWST, and also emits in ultraviolet as detected by the Hubble Space Telescope. Yet, NASA's Chandra X-ray Observatory has also detected faint X-rays originating from Saguaro.

"What the X-ray observations show is that this galaxy has an active galactic nucleus, and a very obscured one at that," Carys Gilbert of the University of Cape Town in South Africa, who participated in the study alongside Rinaldi, said in the statement. "It's not only obscured but also X-ray weak. That kind of combination could explain the lack of X-ray emission that we see from all other little red dots. It fits the puzzle of little red dots nicely."

This is not the first time X-rays have been seen coming from a little red dot. Earlier this year it was reported that scattered X-rays were seen breaking through from a little red dot called 3DHST-AEGIS-12014, given credence to the hypothesis that little red dots are black hole stars, where the black hole gradually consumes the "star" from the inside out, eventually carving holes through which X-rays can escape. We see 3DHST-AEGIS-12014 as it was 11.8 billion years ago, meaning that Saguaro, which existed 1.3 billion years later, is a little bit further on in its development.

"Because the Saguaro is at lower redshift, we can see the very beautiful and bright host galaxy in high resolution and detail with Webb and Hubble," said Harvard's Zihao Wu, who was also part of Rinaldi's team.

Intrigued, Rinaldi's team simulated how Saguaro would appear to us if it existed a billion years after the big bang. Much of its galactic structure would either be less developed or simply just too faint to be seen at such distance. All that would be visible would be the nucleus, looking very much like all the other little red dots.

This implies that little red dots are not a unique population of their own, but are simply a phase in the development of galaxies with supermassive black holes. Our own Milky Way could have been a little red dot once upon a time.

Saguaro is a crucial link in the story of little red dots and how they connect with modern galaxies. While there is still much to learn, such as the beginning of their story and how they form, the middle and end of their story is now beginning to take shape.

The findings were reported on 29 July in The Astrophysical Journal.

In a nebula far, far away, colossal clouds of dust and gas tower amongst the stars.

What is it?

This spectacular new image from the James Webb Space Telescope showcases the brilliant majesty of the Carina Nebula, a giant cloud of dust and gas found 7,500 light-years away in the constellation Carina.

You may have seen the Carina Nebula before — in the first-ever image released from JWST, which has been dubbed "Cosmic Cliffs."

In this new image, captured by JWST's Near-Infrared Camera (NIRCam), you can see the nebula in a whole new light. This snapshot captures a specific feature that is being dubbed the "Treasure Chest," as it vaguely resembles a glowing coffer overflowing with stellar jewels.

This "Treasure Chest" contains a cluster of young stars, approximately 70 stars in total. While these might be young, growing stars, the most massive of the bunch is a whopping 19 times more massive than our sun.

Why is it incredible?

While JWST has looked at the Carina Nebula before, new observations can reveal completely new details and help scientists uncover new information about the nebula and the strange ways in which the universe works.

Right now, scientists think that the star cluster in the "Treasure Chest" is about 1.3 million years old. However, previous estimates thought the grouping could be just 100,000 years old. So, new observations by powerful telescopes like JWST can significantly change our understanding of the cosmos.

With each new observation or data point, the history and context of the universe around us could completely transform. And, as this star cluster grows over time, its stars will become more brilliant. They may therefore illuminate more of this star cluster, potentially revealing details and secrets of this "treasure" that scientists might never have predicted.

Using NASA's long-serving Hubble Space Telescope, astronomers have discovered that a stellar explosion in the Milky Way is blasting out cosmic bullets travelling at 20 million miles per hour.

The cosmic explosion in question is V445 Puppis, which erupted in 2000 and is the only known "helium nova" in our galaxy. Though astronomers have been studying V445 Puppis for two decades, much of the phenomena associated with it were shrouded in mystery due to a vast cloud of dusty debris that surrounded this nova.

When this debris finally cleared, a team of researchers was able to peer into V445 Puppis using Hubble, NASA's exoplanet-hunting spacecraft TESS (Transiting Exoplanet Survey Satellite), and the Earth-based Very Large Telescope (VLT), along with an array of other instruments. This allowed them to discover not only the "bullets", clumps of potentially oxygen-rich gas it is firing, but also the true nature of this system. This revealed that V445 Puppis consists of a dead star hungrily feeding on a companion star that is, by itself, a rare find. Thus, this system offers scientists a rare chance to study one of the rarest types of binary systems and one of the rarest cosmic explosions.

"The origin of these 'bullets' is a mystery. We suspect that these originated post-outburst, but 'bullets' of this kind have not been observed in any other nova," team member John Mills, a researcher at the University of Warwick in the UK, said in a statement.

What is a helium nova?

Helium novas like V445 Puppis occur when a white dwarf dead star cannibalistically strips helium-rich but hydrogen-poor matter from a star that has already lost its outer layer of hydrogen, exposing inner layers of helium; forming a rare "helium star." By contrast, "ordinary" novas are explosions triggered by the buildup of stolen stellar matter rich in hydrogen, not helium.

As the material accumulates on the surface of the white dwarf (a type of stellar remnant left behind when stars around the mass of the sun die) it creates runaway pressures and temperatures that eventually trigger a thermonuclear explosion.

When V445 Puppis went nova back in late 2000, it launched vast, twin plumes of debris that resemble butterfly wings. Stretching out for more than a trillion miles, astronomers initially spotted this bipolar outflow in infrared. The nova also spawned a thick disc of dust that completely obscured the binary star system. That cloud persisted for over two decades, preventing astronomers who were investigating the expanding debris from determining what kind of stars the blast originated from.

Once the debris cleared, this team determined that the system contained a helium star, one of only a few thousand of these stripped stellar bodies to be discovered among the billions of stars that populate the Milky Way.

"The culprits behind this galactic eruption have been an enduring mystery over the past 25 years, which is why it is very exciting to confirm that this helium nova was the result of a helium star accreting onto a white dwarf," Mills said.

The findings also revealed cosmic "bullets" that are even more remarkable, as they have never been seen around any other novas. Intriguingly, the team also found that V445 Puppis may be about to go nova again, and this could lead to an entirely different type of cosmic explosion.

Is V445 Puppis about to blow its top again?

Mills found that the white dwarf in V445 Puppis has overcome its stellar indigestion and is once again feeding on its companion helium star.

This is the process that led to the initial helium nova, and could mean that another episode of this rare type of cosmic explosion is soon to occur.

That has implications for our understanding of another type of cosmic eruption, this time a type of supernova called a Type Ia supernova. These occur when white dwarfs overfeed on companions and are completely destroyed by the resultant explosion.

Scientists have long suspected that repeated helium nova eruptions could lead to final Type Ia supernovas.

A new Type Ia supernova would be exciting because these events are so regular in terms of their light emission that they can be used as so-called "standard candles" to measure cosmic distances and gauge the age of the universe.

This means that they can also be employed in the quest to understand how fast the universe's expansion is proceeding, and the influence of the mysterious force called dark energy on this process.

"I look forward to seeing how this result may help us uncover what powers other similar hydrogen-poor astronomical explosions, such as the famous Type Ia supernovas," Mills said.

The team's research was presented this week at the Royal Astronomical Society's National Astronomy Meeting in Birmingham, UK.

Paleontologists now know that many of the dinosaurs didn't disappear but instead evolved into modern birds, and new research suggests that "cosmic dinosaurs" observed by the James Webb Space Telescope (JWST) didn't go extinct either. Rather, they may have evolved into familiar sights in the modern universe: vast conglomerations of densely packed stars called "globular clusters."

Little Red Dots became quite the puzzle for astronomers in 2022, when the JWST began to routinely spot them in abundance around 600 million years after the Big Bang. That is because these objects seemingly disappear before the cosmos gets to around 2 billion years old.

Astronomers have proposed many different explanations for Little Red Dots, including the suggestion that they could be "black hole stars," or black holes wrapped in vast shrouds of dense gas and dust. This team theorizes that a forming globular cluster with a supermassive star, a hypothetical short-lived stellar body with between 1,000 and 10,000 times the mass of the sun, would also look a lot like a Little Red Dot at its heart.

"These may not be just a strange new JWST population with no connection to the universe around us today," team leader John Chisholm of the University of Texas Austin said in a statement. "Instead, Little Red Dots may persist past the early universe, evolving into something relatively familiar.

"Little Red Dots could be galaxies, they could involve black holes, or they could be something even more unexpected. Our work shows that forming globular clusters with supermassive stars should be part of that conversation."

An unfamiliar side to a familar sight

Globular clusters are generally seen in large galaxies and are densely packed with up to many millions of ancient stars. Our galaxy, the Milky Way, is host to at least 150 globular clusters, and though familiar, astronomers still aren't quite sure how they form.

"We usually see them [globular clusters] after billions of years of evolution, at a time when their massive stars are gone, their gas has been cleared out, and dynamical processes have changed their masses and structures," team member Danielle Berg of UT Austin said in the statement. "That makes it very hard to reconstruct the original conditions they formed in."

It is thought that the stars in globular clusters all formed at the same time in the early universe. However, at this time the cosmos should only have had hydrogen, helium and a smattering of heavier elements (which astronomers call "metals") available for star construction. Yet, many stars in globular clusters are strangely abundant in helium and metals like nitrogen, sodium and aluminum, while lacking the expected levels of carbon, oxygen and magnesium.

"This specific pattern indicates nuclear fusion at very high temperatures, much higher than in the cores of even massive normal stars," team member Mike Boylan-Kolchin of UT Austin said in the statement. "A supermassive star is precisely the kind of environment that could produce this combination."

Supermassive stars capable of generating this kind of heat would form in the dense environments of early globular clusters in which stellar collisions and mergers would be expected to occur over and over again. The resultant supermassive stars would be short-lived, lasting just around 1 million years (remember the sun is middle-aged at 4.6 billion years old) — but this would be sufficient time to forge the elements needed to explain the peculiar chemistry of globular clusters.

When these supermassive stars die in supernova explosions, the elements they forged would be blasted out to become the building blocks of the next generation of stars. This would provide the stars of modern globular clusters with their unusual chemical fingerprints.

"In our model, the supermassive star that helps make the object look like a Little Red Dot would live for only a short time," Chisholm continued. "Once that star dies, the object may no longer look like a Little Red Dot, even if the cluster itself survives billions of years."

Strange chemistry isn't the only thing linking early globular clusters with Little Red Dots, however. Not only does the team propose that the distribution of Little Red Dots in the early universe matches the distribution of modern globular clusters, but they also say models of Little Red Dot evolution show that their estimated masses could easily lead to the masses of globular clusters seen in the recent universe.

There is also the issue of timing. Little Red Dots appear around 600 million years after the Big Bang, and that is also the time that scientists estimate that globular clusters would have begun to form.

"There's no single smoking gun at this point that says Little Red Dots are globular clusters, but it would explain a lot of diverse and surprising observations," said Boylan-Kolchin.

This study is currently available to view as a pre-print on the paper repository arXiv.