Scientists have discovered an entirely new type of star explosion, called a “micronova,” which is like a miniature version of the energetic nova eruptions that illuminate certain dead stars. The breakthrough not only unveils an entirely novel stellar phenomenon, it also solves a decades-long puzzle involving “unexplained rapid bursts” spotted in a system about 1,680 light years from Earth, reports a new study.

Novae are among the most dazzling sights in the night sky, and have been witnessed by astronomers for many centuries. Unlike supernovae, which are the pyrotechnic swan songs of giant stars, novae occur when white dwarfs, the compact corpses of stars like our Sun, end up in binary systems with another star. As the two objects orbit each other, the gravitational pull of the white dwarf tugs stellar material off of its companion as part of a process called accretion, which fuels radiant thermonuclear bursts across the entire surface of the dead star.

For about 40 years, scientists have been perplexed by flashes emitted by one of these white dwarfs, known as TV Columbae, which is in a binary system with a low-mass star. The bursts are relatively dim and they only last for a few hours, whereas typical novae are bright and can shine for several weeks. 

Now, researchers led by Simone Scaringi, an astronomer at Durham University, believe they have solved this long-standing enigma using NASA’s Transiting Exoplanet Survey Satellite (TESS). The team suggests the bursts at TV Columbae, along with two similar white dwarfs called EI Ursae Majoris and ASASSN-19bh, are powered by micronovae that are localized to the poles of these dead stars, a process that may be “more common than previously thought,” according to a study published on Wednesday in Nature.

“The discovery was an unexpected surprise,” Scaringi said in an email. “One of my interests is studying accretion physics. I mostly do this through the use of TESS. We've been running a program with TESS to monitor the brightness variations of a few hundred accreting white dwarfs (as well as candidate accreting [white dwarfs]),” including the three dead stars featured in the new study. 

“These systems are monitored continuously for at least a month and up to a year,” he added. “It was the long observations which allowed us to observe the bright and fast micronovae in action.”

As its name suggests, TESS is primarily tasked with spotting exoplanets, which are worlds that orbit other stars. For this reason, the observatory is designed to flag extremely small variations in the brightness of stars that might hint at the presence of planets crossing in front of them, from our perspective on Earth. 

Scaringi notes that this extreme sensitivity to variable light also distinguishes TESS as an excellent platform for studying accretion bursts around white dwarfs, especially these extremely subtle micronovae, which are so much shorter and dimmer than their novae counterparts. (Though the micronovae are many orders of magnitude smaller than novae, they are still massively energetic eruptions that burn up an amount of material equivalent to 3.5 billion Great Pyramids of Giza.)  

By examining the trio of white dwarfs featured in the study with TESS, as well as the European Southern Observatory’s Very Large Telescope, the team was able to rule out a host of mechanisms that have been previously presented to explain the strange bursts. 

Ultimately, the observations revealed a completely novel scenario in which the magnetic fields of white dwarfs channel accreted material to the poles, where they explode in a localized pattern that is distinct from the global eruptions of regular novae. 

Scientists already knew about these “intermediate polars”—the term for white dwarfs that magnetically direct material to their poles—but the discovery that these systems can generate thermonuclear blasts was completely unanticipated.

“We were surprised,” Scaringi said. “After having discovered the first one in the data, we spent over a year trying to explain the observation with the models we had at hand. It was only when we discovered two other systems in the data displaying micronovae, and noticed that they contained a magnetic accreting white dwarf as well, that we started to join the dots.” 

“Finally, when we made the comparison to the thermonuclear bursts observed in accreting neutron stars it appeared clear to us that what we were seeing were bursts of radiation from localized thermonuclear explosions on white dwarfs,” he added.

Now that this new type of star explosion has been introduced to the scientific community, the team hopes that follow-up observations will capture more transient micronovae out there in our galaxy. These discoveries will help to unravel some of the open questions about the mechanisms behind these bizarre events. 

“To find more, we will need long monitoring observations similar to what TESS is already providing,” Scaringi said. “We are also hoping to promptly follow up these events and catch them in action with X-ray space-based observatories and optical ground-based ones. Given how quickly micronovae happen and fade, this will be challenging!”

 “I think this goes to show just how dynamic the Universe is,” he concluded “These micronova are fast flashes of light that may be quite common out there. It also goes to show that thermonuclear explosions can occur on localized areas (as opposed to the entire surface) of white dwarfs, something that was unexpected and surprising.” 

Astronomers have discovered the most distant individual star ever spotted, located nearly 13 billion light years away, in a stunning breakthrough that was achieved using NASA’s Hubble Space Telescope, reports a new study. 

Because looking across space is also looking back in time, Hubble saw this star as it was when the universe was only about 900 million years old. The star, nicknamed Earendel after the Old English word for “morning star” or “rising light,” is dramatically farther than the previous record-holder, a star named Icarus, also discovered by Hubble, when the universe was already four billion years old.

A team led by Brian Welch, an astronomer at the Johns Hopkins University, was able to glimpse this ancient star, which is about 50 times as massive as the Sun, thanks to the fortuitous position of a huge galaxy cluster positioned between it and Earth. The gravitational fields of such enormous objects can warp and amplify light from objects situated behind them, an effect known as gravitational lensing. In this case, the “star is magnified by a factor of thousands by the foreground galaxy cluster,” according to a study published in Nature on Wednesday.

“At 900 million years after the Big Bang, it’s a time when the universe looked a lot different and we expect the stars there might look a little bit different too,” Welch said in a call. “It's really a new way of studying this early time.”

The new discovery provides an unprecedented look at an individual star within the first billion years of the universe’s 13.8-billion-year lifespan. Galaxies from this period have been observed before, but it is significantly harder to distinguish an individual star that is so far away and so deep in the past. 

For this reason, Welch and his colleagues collected years of observations after they first spotted the star in 2016 with Hubble’s Reionization Lensing Cluster Survey (RELICS), to be sure that they were really seeing a distinct star (or a binary star system). Not only did they confirm the detection, they found that “unlike previous lensed stars, the magnification and observed brightness have remained roughly constant over 3.5 years of imaging and follow-up,” according to the study.

“When we first found it, the main reaction was almost a little bit of disbelief,” said Welch. “We found it by basically identifying that it was at incredibly high magnification, which seemed a little bit unusual, and it's a somewhat different way than previous lensed stars have been detected.” 

“It kicked off a long process of guessing and checking and figuring out if there was any other explanation,” he continued. “So at that first moment, we were a little unsure, but once we finally got there, it was really exciting to know that this was something that was so much further than we've been able to see in the past.”

The galaxy that hosts Earendel appears stretched out into a long crescent by the lensing effect, earning it the name the Sunrise Arc. While the discovery is exciting as a standalone event, Welch and his colleagues think that it also raises the possibility of spotting more of these stellar elders in the early days of the universe. Hubble’s successor, the recently launched James Webb Space Telescope (JWST), will be especially useful in the search for stars from this bygone cosmic age.

“We do expect, with the Webb space telescope, that we will be able to find more of these sorts of objects,” Welch said. “Within the first couple of years, at least, of Webb observations, we’re really hoping that we're going to be able to find more objects like this and break this record pretty soon, because it would be really exciting to continue looking further back into the universe with these individual stars.”

These follow-up observations might also be able to determine if Earendel is among the first stars ever born in the universe, a group called Population III which has never been directly observed before. Whereas modern stars are enriched with heavy elements that have been forged in the bellies of their forebears for billions of years, Population III stars are thought to be made almost entirely of hydrogen and helium, with a possible trace of other light elements, making them curious relics rich with information about the evolution of stars.

“It is very unlikely to be a Population III star,” Welch noted. “About 900 million years after the Big Bang is almost certainly enough time for at least one other star to have gone off and slightly enriched the area that this star formed in.” 

“If we did find that it was a Population III star, that would obviously be huge,” he continued. “If we were able to confirm that with future observations, that would be the first Population III star ever discovered and confirmed, so it would be an incredibly exciting thing to find. There's a small chance that we'll get that lucky, but I would say, probably, don't count on it.”

Update: This article has been updated to include comments from study lead author Brian Welch.

For the first time ever, all four major components of DNA, the biological blueprint of living things, have been detected in rocks from outer space, a discovery that suggests the building blocks of life may have been delivered to Earth by ancient extraterrestrial objects, according to a new study.

DNA is a helical structure made of so-called “nucleobases”—the compounds adenine, guanine, cytosine, and thymine—which combine in motley permutations to write the source code for life on Earth, including humans. Though adenine and guanine were found in meteorites about 50 years ago, the presence of cytosine and thymine in these extraterrestrial objects has remained elusive, despite evidence that the compounds might have existed in the primordial interstellar dust that gave rise to our solar system some 4.6 billion years ago. 

Now, scientists led by Yasuhiro Oba, a professor at Hokkaido University, have at last detected trace amounts of cytosine and thymine in three carbonaceous (carbon-rich) meteorites, a finding that bolsters the notion that extraterrestrial impacts ”contributed to the emergence of genetic properties for the earliest life on Earth,” according to a study published in Tuesday in the journal Nature Communications.

The two newly detected nucleobases belong to a group called the pyrimidines, whereas adenine and guanine are categorized as purines. In addition to discovering the remaining compounds inside DNA, Oba and his colleagues also found traces of another pyrimidine called uracil, which is used by RNA, a simpler sister molecule of DNA, instead of thymine. Though uracil has been identified in meteorites before, the discovery of all three pyrimidines in the space rocks sheds new light on the puzzling scarcity of these nucleobases in meteorites, compared to the purines adenine and guanine.

“The lack of pyrimidine diversity in meteorites remains a mystery since prebiotic chemical models and laboratory experiments have predicted that these compounds can also be produced from chemical precursors found in meteorites,” Oba’s team said in the study. “Here we report the detection of nucleobases in three carbonaceous meteorites using state-of-the-art analytical techniques optimized for small-scale quantification of nucleobases down to the range of parts per trillion (ppt).” 

“In addition to previously detected purine nucleobases in meteorites such as guanine and adenine, we identify various pyrimidine nucleobases such as cytosine, uracil, and thymine,” they added. “This study demonstrates that a diversity of meteoritic nucleobases could serve as building blocks of DNA and RNA on the early Earth.”

The team achieved this breakthrough by analyzing samples from the Murchison, Murray and Tagish Lake meteorites, which landed in Australia, Oklahoma, and British Columbia, respectively. The research follows a number of related studies of these meteorites, and others, that have found proteins, nitrogen, water, organic compounds, and other key ingredients for life in extraterrestrial objects that ended up on Earth, potentially planting the seeds of habitability on our infant planet. 

It’s even possible that nascent lifeforms could have been transferred between worlds—such as Earth and Mars—through a process known as panspermia, in which organisms are able to survive interplanetary voyages by hitchhiking on meteorites ejected by impacts on their home worlds.

While it’s still not clear why the purines are more readily detectable in the space rocks, the researchers think that all these nucleobases could have been formed by photochemical processes in the interstellar medium, “suggesting that these classes of organic compounds are ubiquitously present in extraterrestrial environments both inside and outside the solar system,” according to the study. 

In other words, the new findings not only help to unravel the tale of our own origins as Earthlings, they may also inform our search for alien life elsewhere in the universe. The advent of sample-return missions such as NASA’s OSIRIS-REx, which will deliver pristine material from a carbonaceous asteroid to Earth next year, will further constrain these most essential human questions of how life began on our planet, and whether it exists elsewhere.

Scientists have shed light on a longstanding mystery about ancient supermassive black holes and the galaxies they inhabit by peering at incredibly luminous objects that existed in the early universe, just 500 million to one billion years after the Big Bang, reports a new study.

Black holes are mind-boggling regions of the cosmos that contain so much mass in such a small space that nothing, not even light, can escape their gravitational forces. Though there are unanswered questions about black holes of all sizes and ages, the supermassive black holes that inhabited the early universe are particularly inscrutable.

For instance, it’s unclear how these monster objects became so gargantuan—with some reaching masses one billion times that of the Sun—so early in the timeline of the universe. Moreover, scientists have long been puzzled about what slowed those early growth spurts and guided supermassive black holes into a more symbiotic development with their host galaxies. 

Now, scientists led by Manuela Bischetti, a postdoctoral researcher for Italy’s National Institute for Astrophysics at the Astronomical Observatory of Trieste, have made the unexpected discovery that extremely strong winds from early supermassive black holes likely slowed their growth. Bischetti and her colleagues observed 30 quasars, extremely luminous objects often found in the center of ancient galaxies, and identified these winds as an initial stage of “black hole feedback,” a process that is central to the development of modern galaxies, including our own Milky Way, according to a study published on Wednesday in Nature.   

“This result highlights for the first time that black hole feedback has an important role in shaping the early growth phases of both black holes and galaxies, and that the strength of black hole feedback may evolve with time,” Bischetti said in an email. “This provides key constraints for theoretical models of galaxy evolution.”

Supermassive black holes exist at the center of most galaxies; for instance, the Milky Way contains an object that is about four million times as massive as the Sun. Scientists have found an oddly specific correlation between the masses of black holes and their host galaxies in what’s known as the “low-redshift” universe, which is another way to describe the modern universe we live in, where light waves are not as stretched into red wavelengths as more ancient light from the early “high-redshift” universe. Low-redshift galaxies tend to be about 100 times more massive than their central black holes, a ratio that is so consistent that it hints at a symbiotic growth process between the black holes and their galaxies, in which the structures stabilize each others’ development. 

However, as Bischetti explained, “this is not true for the high redshift universe and for the quasars in our study, for which we observe that the black-holes are overmassive (ten times more massive) with respect to their host galaxies.”

“This implies that, during the first billion years of the universe, black holes must have grown more rapidly than their host galaxies,” she added. 

Bischetti and her colleagues were able to study these brilliant quasars with “a high signal-to-noise” ratio by capturing 250 hours of observations with the “X-shooter” spectrograph at the European Southern Observatory’s Very Large Telescope in Chile, according to the study. The team hoped the X-shooter would provide a more detailed glimpse of the winds, or outflows, fueled by these early supermassive black holes, which tear through early galaxies, influencing their development. 

“This research was motivated by the fact that, although astronomers expect black holes to strongly affect the evolution of galaxies when the universe was about one billion years old, there are very few observations with sufficient quality to either support or reject this,” Bischetti said. 

To their astonishment, the researchers discovered that black hole winds in the early universe were extremely common and about 20 times more powerful than those in the modern universe. Some outflows in their observations shot into space at 17 percent the speed of light, a process that redistributes energy into their host galaxies and likely slammed the brakes on early black hole growth, possibly kicking off the stable feedbacks we see in galaxies today. 

“We were expecting to find that black hole winds in the young universe work similarly to what we observe at later epochs, in the universe closer to us,” she added. “Instead, we were very surprised and excited by the great deal of very energetic winds that we discovered, as this points towards a strong evolution of black hole feedback with time.”

While the study offers a compelling look at this major transition in the relationship between galaxies and their central black holes, Bischetti said it will take more observations to unravel further details about this dance between cosmic giants at the edge of space and time. 

Ultimately, the researchers hope to use next generation telescopes, including the recently launched James Webb Space Telescope and the forthcoming Extremely Large Telescope in Chile, to zoom into the influence of the black hole winds on early galaxies and their stars.

“We now wish to follow-up this study by understanding whether and how the observed black hole outflows affect the growth of the host galaxy,” Bischetti said, adding that current telescopes can only spot “the brightest tip of the iceberg of the population of quasars at these very high redshifts.” 

“We expect that intrinsically fainter objects will show different properties in terms of outflows with respect to the XQR-30 sample”—referring to the 30 quasars observed in this study—”but at the moment it is extremely challenging to test this hypothesis,” she concluded.