A conspicuous “chirp” heralded the first detection of gravitational waves. But some future measurements could be more like hushed murmurs.
Scientists may soon be able to tease out a faint signal of gravitational waves from black hole collisions too distant to be detected directly, scientists with LIGO, the Advanced Laser Interferometer Gravitational-Wave Observatory, report in the April 1 Physical Review Letters. A detection could come in as few as three years — considerably faster than scientists had dreamed possible, the new analysis suggests. When LIGO detected the stretching and squeezing of spacegenerated by a pair of merging black holes, scientists were wowed (SN: 03/05/16, p. 6). The signal stood out well above spurious bumps and wiggles in the data, which are ever-present in LIGO’s extremely sensitive detectors. It rose swiftly in frequency — when converted to sound waves, it was reminiscent of a bird’s chirp — a hallmark of the black holes’ inward-spiraling cosmic dance.
But such obvious swells are outnumbered by a sea of smaller ripples. With these ripples, “you’re looking at black holes which are much farther away,” says LIGO spokesperson Gabriela González of Louisiana State University in Baton Rouge.
LIGO is not sensitive enough to detect these waves outright, but by comparing the data recorded by LIGO’s separate detectors — one in Louisiana and one in Washington state — scientists could identify patterns revealing the presence of the background waves. Such a measurement would allow scientists to compare black hole populations of different ages and could help nail down the conditions under which black hole pairs form.
“My honest opinion was, ‘I’m going to be lucky if we see this result in my lifetime,’” says physicist Emanuele Berti of the University of Mississippi in Oxford, who is not involved with LIGO. He has changed his tune. “Nature was good to us, and now we think that we’re going to be able to see them pretty soon.”
That’s because new estimates of the rate of such black hole mergers are higher than many scientists expected. Using models of binary black hole populations combined with LIGO data, scientists find that LIGO could be sensitive to nearly 2,000 such black hole mergers a year, meeting their most optimistic predictions.
The possibility shows LIGO’s versatility, González says. “There are good prospects of all kinds — it’s not just detections of single events.”
The world’s known helium reserves just ballooned. Applying gas-finding techniques from the oil industry, scientists uncovered a vast reservoir of more than a trillion liters of helium gas beneath Tanzania. That’s enough to satisfy the world’s helium needs for around seven years, the researchers announced June 28 at the Goldschmidt Conference, a geochemistry meeting being held in in Yokohama, Japan. The find may allay fears that a global helium shortage will hit when the U.S. Federal Helium Reserve — currently the world’s largest helium source — runs dry within the next few years.
While previously known helium reserves were discovered by chance during oil and gas exploration, geologist Diveena Danabalan of Durham University in England and colleagues applied geologic know-how to their helium hunt. Helium accumulates underground during the radioactive decay of unstable elements such as uranium. That helium, though initially trapped, can be liberated when surrounding rock melts during volcanic activity. Using this information as well as seismic imaging of gas-trapping underground formations, the researchers discovered five spots in a volcanic region of Tanzania where water and helium-rich gas bubble to the surface from underground reservoirs.
The researchers predicted that they will be able to find more helium reservoirs and help meet society’s helium needs. Those needs go beyond just making balloons float and voices sound squeaky: Helium is essential for scientific research and a critical component of the cooling systems that allow medical MRI scanners to function.
Analyzing a bevy of diverse data, scientists have drawn a new map of the human brain in extreme relief. Their approach demarcated 180 areas in each half of the outer layer of the brain — including 97 regions in each half that haven’t been described before. The high-resolution map will allow scientists to more precisely scrutinize brain regions and see how they change with, for instance, age and disease.
Many previous maps of the brain have been built with just one type of data. The new map, described July 20 in Nature, forms a holistic view of the brain by combining several different types of information. These specs included how areas behaved while doing certain tasks or nothing at all, as well as detailed anatomical data about the shape and thickness of the brain. Using these metrics from 210 healthy people, neuroscientist David Van Essen of Washington University in St. Louis and colleagues found that each hemisphere contains 180 distinct areas (separated by black lines in image). In this view, colors show how tightly linked each area is to other brain areas that handle auditory (red), touch and movement (green) or visual (blue) information.
It’s hard to pin down Stephen Wolfram’s scientific discipline. He is part mathematician, part computer scientist, part physicist. He’s also an inventor and entrepreneur, known for the mathematics software package Mathematica and a variety of other endeavors. And he blogs.
Among his blog posts and other essays and talks are commentaries on the lives of other prominent figures from science and math; some Wolfram knew personally, others he has researched extensively. In his new book Idea Makers, Wolfram has collected accounts of 16 such people, discussing their work and its meaning for the nature of science and the process of understanding math, computing and the physical world. Each entry provides a healthy dose of personal information as well. Some of the people Wolfram discusses are widely known — Richard Feynman and Steve Jobs, for example. Others are relatively obscure, such as Russell Towle and Richard Crandall. But all have captivated Wolfram’s interest, either by way of friendship or their historical importance for the fields of study that Wolfram himself has contributed to.
On the historical side, Wolfram offers his views of the logician Kurt Gödel, computer scientist (perhaps the original computer scientist) Alan Turing and mathematicians John von Neumann and George Boole. Wolfram provides an especially extensive discussion of Ada Lovelace and her interactions with Charles Babbage as they contemplated the prospect of powerful computing engines a century ahead of their time.
Wolfram also dives into the story of Srinivasa Ramanujan, and the lessons his genius offers about the nature of math. With little formal training, Ramanujan discovered many surprising results that seemed at first glance to be a bunch of “random facts of mathematics.” But in recent decades, many have been linked to deep mathematical principles that he seems to have somehow perceived without knowing it. How did he do it? Wolfram suspects that he “had intuition and aesthetic criteria that in some sense captured some of the deeper principles we now know, even if he couldn’t express them directly.”
Personal style, whether as reflected in the subtle genius of Ramanujan or the boldness of vision-driven Jobs, plays an underappreciated role in the progress of science and technology. Wolfram has collected some illuminating examples of the ways the human side of scientific thinkers can enrich the work they do.
SAN DIEGO — Over the course of months, clumps of a protein implicated in Parkinson’s disease can travel from the gut into the brains of mice, scientists have found.
The results, reported November 14 at the annual meeting of the Society for Neuroscience, suggest that in some cases, Parkinson’s may get its start in the gut. That’s an intriguing concept, says neuroscientist John Cryan of the University College Cork in Ireland. The new study “shows how important gut health can be for brain health and behavior.” Collin Challis of Caltech and colleagues injected clumps of synthetic alpha-synuclein, a protein known to accumulate in the brains of people with Parkinson’s, into mice’s stomachs and intestines. The researchers then tracked alpha-synuclein with a technique called CLARITY, which makes parts of the mice’s bodies transparent.
Seven days after the injections, researchers saw alpha-synuclein clumps in the gut. Levels there peaked 21 days after the injections. These weren’t the same alpha-synuclein aggregates that were injected, though. These were new clumps, formed from naturally occurring alpha-synuclein, that researchers believe were coaxed into forming by the synthetic versions in their midst.
Also 21 days after the injections, alpha-synuclein clumps seemed to have spread to a part of the brain stem containing nerve cells that make up the vagus nerve, a neural highway that connects the gut to the brain. Sixty days after the injections, alpha-synuclein had accumulated in the midbrain, a region packed with nerve cells that make the chemical messenger dopamine. These are the nerve cells that die in people with Parkinson’s, a progressive brain disorder that affects movement.
After reaching the brain, alpha-synuclein spreads thanks in part to brain cells called astrocytes, a second study suggests. Experiments with cells in dishes showed that astrocytes can store up and spread alpha-synuclein among cells. That work was presented by Jinar Rostami of Uppsala University in Sweden at a news briefing on November 14.
The gradual accumulation and spread of alpha-synuclein caused trouble in the mice. As alpha-synuclein clumps slowly crept brainward, the mice began exhibiting gut and movement problems. Seven days after the injections, the mice’s stool was more plentiful than usual. Sixty and 90 days after the injections — after clumps of alpha-synuclein had reached the brain — the mice performed worse on some physical tests, including getting a sticker off their face and flipping around to shimmy down a pole headfirst. In many ways, the mice resembled other mice that have mutations that cause Parkinson’s-like symptoms, Challis says. An earlier study turned up evidence that clumps of alpha-synuclein can move from the gut to the brain stem in rats, but those experiments looked at shorter time scales, Challis says. And previous work monitored the movements of the injected alpha-synuclein, as opposed to the alpha-synuclein clumps that the mice produced themselves.
The idea that alpha-synuclein can spread from the gut to the brain is very new, says Alice Chen-Plotkin, a clinician and Parkinson’s researcher at the Hospital of the University of Pennsylvania. These new results and others have prompted scientists to start looking outside of the brain for the beginning stages of the disease, she says. “Increasingly, people are wondering if it starts earlier.”
Some evidence suggests that the gut is a good place to look. People with Parkinson’s disease often suffer from gut problems such as constipation. And in 2015, scientists reported that a group of Danish people who had their vagus nerves severed were less likely to develop Parkinson’s disease. Cut alpha-synuclein’s transit route from the gut to the brain, and the disease is less likely to take hold, that study hints.
It’s not clear why alpha-synuclein accumulates in the gut in the first place. “There are a lot of theories out there,” Challis says. Bacteria may produce compounds called curli that prompt alpha-synuclein to aggregate, a recent study suggests. Pesticides, acid reflux and inflammation are other possible culprits that could somehow increase alpha-synuclein clumps in the gut, Challis says.
Not all galaxies sparkle with stars. Galaxies as wide as the Milky Way but bereft of starlight are scattered throughout our cosmic neighborhood. Unlike Andromeda and other well-known galaxies, these dark beasts have no grand spirals of stars and gas wrapped around a glowing core, nor are they radiant balls of densely packed stars. Instead, researchers find just a wisp of starlight from a tenuous blob.
“If you took the Milky Way but threw away about 99 percent of the stars, that’s what you’d get,” says Roberto Abraham, an astrophysicist at the University of Toronto. How these dark galaxies form is unclear. They could be a whole new type of galaxy that challenges ideas about the birth of galaxies. Or they might be outliers of already familiar galaxies, black sheep shaped by their environment. Wherever they come from, dark galaxies appear to be ubiquitous. Once astronomers reported the first batch in early 2015 — which told them what to look for — they started picking out dark denizens in many nearby clusters of galaxies. “We’ve gone from none to suddenly over a thousand,” Abraham says. “It’s been remarkable.” This haul of ghostly galaxies is puzzling on many fronts. Any galaxy the size of the Milky Way should have no trouble creating lots of stars. But it’s still unclear how heavy the dark galaxies are. Perhaps these shadowy entities are failed galaxies, as massive as our own but mysteriously prevented from giving birth to a vast stellar family. Or despite being as wide as the Milky Way, they could be relative lightweights stretched thin by internal or external forces. Either way, with so few stars, dark galaxies must have enormous deposits of unseen matter to resist being pulled apart by the gravity of other galaxies.
Astronomers can’t resist a good cosmic mystery. With detections of these galactic oddballs piling up, there is a push to figure out just how many of these things are out there and where they’re hiding. “There are more questions than answers,” says Remco van der Burg, an astrophysicist at CEA Saclay in France. Cracking the code of dark galaxies could provide insight into how all galaxies, including the Milky Way, form and evolve. Compound eye on the sky Telescopes designed to detect faint objects have revealed the presence of many sizable but near-empty galaxies — officially known as “ultradiffuse galaxies.” The deluge of discoveries started in New Mexico, with a telescope that looks more like a honeycomb than a traditional observatory. Sitting in a park about 110 kilometers southwest of Roswell (a city that has turned extraterrestrials into a tourism industry), the Dragonfly telescope consists of 48 telephoto lenses; it started with three in 2013 and continues to grow. The lenses are divided evenly among two steerable racks, and each lens is hooked up to its own camera. Partly inspired by the compound eye found in dragonflies and other insects, this relatively small scope has revealed dim galaxies missed by other observatories.
The general rule for telescopes is that bigger is better. A large mirror or lens can collect more light and therefore see fainter objects. But even the biggest telescopes have a limitation: unwanted light. Every surface in a telescope is an opportunity for light coming in from any direction to reflect onto the image. The scattered light shows up as dim blobs, or “ghosts,” that can wash out faint detail in pictures of space or even mimic very faint galaxies.
Large dark galaxies look a lot like these ghosts, and so went unnoticed. But Dragonfly was designed to keep these splashes of light in check. Unlike most conventional professional telescopes, it has no mirrors. Precision antireflection coatings on the lenses keep scattered light to a minimum. And having multiple cameras pointed at the same part of the sky helps distinguish blobs of light bouncing around in the telescope from blobs that actually sit in deep space. If the same blob shows up in every camera, it’s probably real.
“It’s a very clever idea, very brilliant,” says astronomer Jin Koda of Stony Brook University in New York. “Dragonfly made us realize that there is a chance to find a new population of galaxies beyond the boundary of what we know so far.”
In spring 2014, researchers pointed Dragonfly at the well-studied Coma cluster, a conglomeration of thousands of galaxies. At a distance of about 340 million light-years, Coma is a close, densely packed collection of galaxies and a rich hunting ground for astronomers. A team led by Abraham and astronomer Pieter van Dokkum of Yale University was looking at the edges of galaxies for far-flung stars and stellar streams, evidence of the carnage left behind after small galaxies collided to build larger ones. They were not expecting to find dozens of galaxies hiding in plain sight. “People have been studying Coma for 80 years,” Abraham says. “How could we find anything new there?” And yet, scattered throughout the cluster appeared 47 dark galaxies, many of them comparable in size to the Milky Way — tens of thousands to hundreds of thousands of light-years across (SN: 12/13/14, p. 9). This was perplexing. A galaxy that big should have no problem forming lots of stars, van Dokkum and colleagues noted in September in Astrophysical Journal Letters.
Hidden strength Even more surprising, says Abraham, is that those galaxies survive in Coma, a cluster crowded with galactic bullies. A galaxy’s own gravity holds it together, but gravity from neighboring galaxies can pull hard enough to tear apart a smaller one. To create sufficient gravity to survive, a galaxy needs mass in the form of stars, gas and other cosmic matter. In a place like Coma, a galaxy needs to be fairly massive or compact. But with so few stars (and presumably so little mass) spread over a relatively large space, dark galaxies should have been shredded long ago. They are either recent arrivals to Coma or a lot stronger than they appear.
From what researchers have learned so far, dark galaxies seem to have been lurking for many billions of years. They are located throughout their home clusters, suggesting that they’ve had a long time to spread out among the other galaxies. And the meager stars they have are mostly red, indicating that they are very old. With this kind of longterm survival, dark galaxies probably have a hidden strength, most likely due to dark matter.
All galaxies are loaded with dark matter, a mysterious substance that reveals itself only via gravitational interactions with luminous gas and stars. Much of that dark matter sits in an extended blob (known as the halo) that reaches well beyond the visible edge of a galaxy. On average, dark matter accounts for about 85 percent of all the matter in the universe. Within the central regions of the dark galaxies in Coma, dark matter must make up about 98 percent of the mass for there to be enough gravity to keep the galaxy intact, van Dokkum and colleagues say. Dark galaxies appear to have similar fractions of dark matter focused near their cores as the Milky Way does throughout its broader halo.
Astronomers had never seen such a strong preference for dark matter in galaxies so large. The initial cache of galactic enigmas lured a slew of researchers to the hunt. They pored over existing images of Coma and other clusters, looking for more dark galaxies. These galaxies are so faint that they could easily blend in with a cluster’s background light or be mistaken for reflections within a telescope. But once the galaxy hunters knew what to look for, they were not disappointed — those first 47 were just the tip of the iceberg.
Looking at old images of Coma taken by the Subaru telescope in Hawaii, Koda and colleagues easily confirmed that those 47 were really there. But that wasn’t all. They found a total of 854 dark galaxies, 332 of which appeared to be roughly the size of the Milky Way (SN: 7/25/15, p. 11). They calculated that Coma could harbor more than 1,000 dark galaxies of all sizes — comparable to its number of known galaxies. Astronomer Christopher Mihos of Case Western Reserve University in Cleveland and colleagues, reporting in 2015 in Astrophysical Journal Letters, found three more in the Virgo cluster, a more sparsely populated but closer gathering of galaxies that’s a mere 54 million light-years away.
In June, van der Burg and collaborators reported another windfall in Astronomy & Astrophysics. Using the Canada-France-Hawaii Telescope atop Mauna Kea in Hawaii, they measured the masses of several galaxy clusters. Taking a closer look at eight clusters, all less than about 1 billion light-years away, the group found roughly 800 more ultradiffuse galaxies.
“As we go to bigger telescopes, we find more and more,” says Michael Beasley, an astrophysicist at Instituto de Astrofísica de Canarias in Santa Cruz de Tenerife, Spain. “We don’t know how many there are, but we know there are a lot of them.” There could even be more dark galaxies than bright ones.
Nature vs. nurture What dark galaxies are and how they formed is still a mystery. There are many proposals, but with so little data, few conclusions. For the vast majority of dark galaxies, researchers know only how big and how bright each one is. Three so far have had their masses measured. Of those, two appear to have more in common masswise with some of the small galaxies that orbit the Milky Way, while the third is as massive as our galaxy itself — roughly 1 trillion times as massive as the sun.
A dark galaxy in the Virgo cluster, VCC 1287, and another in Coma, Dragonfly 17, each have a total mass of about 70 billion to 90 billion suns. But only about one one-thousandth of that or less is in stars. The rest is dark matter. That puts the total masses of these two galaxies on par with the Large Magellanic Cloud, the largest of the satellite galaxies that orbit the Milky Way. But focus on just the mass of the stars, and the Large Magellanic Cloud is about 35 times as large as Dragonfly 17 and roughly 100 times as large as VCC 1287.
A galaxy dubbed Dragonfly 44, however, is another story. It’s a dark beast, weighing about as much as the entire Milky Way and made almost entirely of dark matter, van Dokkum and colleagues report in September in Astrophysical Journal Letters. “It’s a bit of a puzzle,” Beasley says. “If you look at simulations of galaxy formation, you expect to have many more stars.” For some reason, this galaxy came up short. The environment may be to blame. A cluster like Coma grows over time by drawing in galaxies from the space around it. As galaxies fall into the cluster, they feel a headwind as they plow through the hot ionized gas that permeates the cluster. The headwind can strip gas from an incoming galaxy. But galaxies need gas to form stars, which are created when self-gravity crushes a blob of dust and gas until it turns into a thermonuclear furnace. If a galaxy falls into the cluster just as it is starting to make stars, this headwind might remove enough gas to prevent many stars from forming, leaving the galaxy sparsely populated.
Or maybe there’s something intrinsic to a galaxy that turns it dark. A volley of supernovas or a prolific burst of star formation might drive gas out of the galaxy. Nicola Amorisco of the Max Planck Institute for Astrophysics in Garching, Germany, and Abraham Loeb of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass., suggest that ultradiffuse galaxies start off as small galaxies that spun rapidly as they formed. All galaxies rotate, but perhaps dark galaxies are a subset that twirl so fast that their stars and gas have spread out, turning them into diffuse blobs rather than star-building machines.
To test these and other ideas, astronomers are focused on two key pieces of information: the masses of these galaxies and their locations in the universe. Mass can help researchers distinguish between formation scenarios, such as whether or not dark galaxies are failed Milky Way–like behemoths. A survey of other locales would indicate whether dark galaxies are unique to big clusters such as Coma, suggesting that the environment plays a role in their creation. But if they turn up outside of clusters, isolated or with small groups of galaxies, then perhaps they’re just born that way.
There’s already a hint that dark galaxies depend more on nature than nurture. Yale astronomer Allison Merritt and colleagues reported in October online at arXiv.org that four ultradiffuse galaxies lurk in a small galactic gathering about 88 million light-years away, indicating that clusters aren’t the only place dark galaxies can be found. And van der Burg, in his survey of eight clusters, found that dark galaxies make up the same fraction of all galaxies in a cluster regardless of cluster mass — at least, for clusters weighing between 100 trillion and 1 quadrillion times the mass of the sun. About 0.2 percent of the mass of the stars is tied up in the dark galaxies. Since all eight clusters host roughly the same relative number of dark galaxies, that suggests that there is something intrinsic about a galaxy that makes it dark, van der Burg says.
What this all means for understanding how galaxies form is hard to say. These cosmic specters might be an entirely new entity that will require new ideas about galaxy formation. Or they could be one page from the galaxy recipe book. Timing, location and luck might send some of our heavenly neighbors toward a bright future and force others to fade into the background. Perhaps dark galaxies are a mixed bag, the end result of many different processes going on in a variety of environments.
“I see no reason why the universe couldn’t make these things in many ways,” Abraham says. “Part of the fun over the next few years will be to figure out which is in play in any particular galaxy and what sort of objects the universe has chosen to make.”
What is clear is that as astronomers push to new limits — fainter, farther, smaller — the universe turns up endless surprises. Even in Coma, a locale that has been intensively studied for decades, there are still things to discover. “There’s just a ton of stuff out there that we’re going to find,” Abraham says. “But what that is, I don’t know.”
You may have read the news this week that pregnancy shrinks a mother’s brain. As a mom-to-be’s midsection balloons, areas of her cerebral cortex wither, scientists reported online December 19 in Nature Neuroscience.
Yes, that sounds bad. But don’t fret. As I learned in reporting that story, a smaller brain can be more efficient and specialized. In fact, post-pregnancy brains could be considered evolutionary works of art, perfectly sculpted to better respond to their babies. The researchers found that the brain regions most changed during pregnancy are the ones that fire up when mothers see pictures of their babies. Pregnancy (and possibly childbirth) may make these neural networks sleeker and stronger, helping moms to tune in to their infants.
As someone whose brain has shriveled at least one time, maybe twice (scientists don’t know if the brain keeps getting smaller with subsequent pregnancies), I find it fascinating to think about this remodeling. The lingering question, however, is whether those brain changes relate to a mother’s smarts. The world abounds with anecdotal attacks of baby brain and placenta dementia (a name that both entertains and offends me), but are the conditions real? Do pregnant women and new moms really turn into forgetful, bumbling idiots?
Study coauthor Elseline Hoekzema, a neuroscientist at Leiden University in the Netherlands, says that the data on this are fuzzy. “It is not well-established whether there are objective changes in memory as a result of pregnancy,” she says. Some studies find effects, while others find none. Research round-ups indicate that certain kinds of memory may be affected, leaving others unscathed. In their study of 25 first-time mothers, Hoekzema and her colleagues didn’t find any memory changes from pre-pregnancy to the months after they gave birth. This study didn’t test the women while they were pregnant, though.
But there are signs of memory slips during pregnancy and the immediate aftermath in both people and animals, says neuroscientist Liisa Galea of the University of British Columbia in Vancouver. Those results vary depending on trimester, fetal sex and other factors, she says. My first thought on hearing those results was, “of course.” Anyone forced to sleep in two-hour increments for months at a time will have trouble remembering things. But Galea says that extreme exhaustion can’t account for the deficits.
Lest mothers despair, Galea pointed me to some different research by her and others that indicates after this early rough spell, motherhood may actually make the brain stronger. In a maze test, first-time rat mothers that were no longer nursing their babies actually outperformed rats that had never given birth. And rats that had been pregnant multiple times outperformed non-mother rats on a different memory test, Galea says.
What’s more, motherhood may help keep the brain young. When tested at the ripe old age of 24 months, rats that had given birth earlier in life performed better on tests of learning and memory than rats that had not given birth. Those results suggest that something about motherhood — perhaps the stew of hormones and the brain changes that follow — may actually protect the brain as it ages.
Despite the spotty scientific literature on these sorts of changes in women, Galea thinks the evidence suggests that there’s a temporary dip in memory during pregnancy and the early postpartum period, followed by not just a recovery, but an actual improvement. “Pregnancy and motherhood are dramatic life-changing events that can have long-lasting repercussions in the brain,” she says. And it’s quite likely that some of those repercussions might be good.
GRAPEVINE, TEXAS — Green was all the rage a couple of billion years after the Big Bang.
Galaxies in the early universe blasted out a specific wavelength of green light, researchers reported January 7 at a meeting of the American Astronomical Society. It takes stars much hotter than most stars found in the modern universe to make that light. The finding offers a clue to what the earliest generation of stars might have been like (SN: 10/1/16, p. 25). Some nearby galaxies and nebulas produce a little bit of this hue today. But these early galaxies, seen as they were roughly 11 billion years ago, produce an overwhelming amount. “Everybody was doing it,” said Matthew Malkan, an astrophysicist at UCLA. “It seems like all galaxies started this way.”
Malkan and colleagues used the United Kingdom Infrared Telescope in Hawaii and the Spitzer Space Telescope to collect the light from over 5,000 galaxies. They found that, in all of these galaxies, one wavelength of green light — now stretched to infrared by the expansion of the universe — was twice as bright compared with light from the typical mix of stars and gas seen in galaxies today.
The green light comes from oxygen atoms that have lost two of their electrons. To knock off two electrons requires harsh ultraviolet radiation, possibly from lots of extremely hot stars — each roughly 50,000° Celsius. The sun, by comparison, is about a paltry 5,500° C at its surface.
“Stars must have been much hotter than most energetic stars familiar to us today,” said Malkan. How they got so hot — perhaps via exotic chemical abundances or just piling on lots of mass — is unsettled.
Hawk moths have a sweet solution to muscle damage.
Manduca sexta moths dine solely on nectar, but the sugary liquid does more than fuel their bodies. The insects convert some of the sugars into antioxidants that protect the moths’ hardworking muscles, researchers report in the Feb. 17 Science.
When animals expend a lot of energy, like hawk moths do as they rapidly beat their wings to hover at a flower, their bodies produce reactive molecules, which attack muscle and other cells. Humans and other animals eat foods that contain antioxidants that neutralize the harmful molecules. But the moths’ singular food source — nectar — has little to no antioxidants.
So the insects make their own. They send some of the nectar sugars through an alternative metabolic pathway to make antioxidants instead of energy, says study coauthor Eran Levin, an entomologist now at Tel Aviv University. Levin and colleagues say this mechanism may have allowed nectar-loving animals to evolve into powerful, energy-intensive fliers.
After an influenza infection, the nose recruits immune cells with long memories to keep watch for the virus, research with mice suggests.
For the first time, this type of immune cell — known as tissue resident memory T cells — has been found in the nose, researchers report June 2 in Science Immunology. Such nasal resident memory T cells may prevent flu from recurring. Future nasal spray vaccines that boost the number of these T cells in the nose might be an improvement over current flu shots, researchers say. It’s known that some T cell sentinels take up residence in specific tissues, including the brain, liver, intestines, skin and lungs. In most of these tissues, the resident memory T cells start patrolling after a localized infection. “They’re basically sitting there waiting in case you get infected with that pathogen again,” says Linda Wakim, an immunologist at the University of Melbourne in Australia. If a previous virus invades again, the T cells can quickly kill infected cells and make chemical signals, called cytokines, to call in other immune cells for reinforcement. These T cells can persist for years in most tissues.
It’s different in the lungs. There, resident memory T cells have shorter-term memories than ones that reside in other tissues, scientists have previously found. To see if all tissues in the respiratory tract have similarly forgetful immune cells, Wakim and colleagues tagged immune cells in mice and sprayed flu virus in the rodents’ noses. After infection, resident memory T cells settled into the nasal tissue. The researchers haven’t yet dissected any human noses, but it’s a pretty good bet they also contain resident memory T cells, Wakim says. Unlike in the lungs, the nose T cells had long memories, persisting for a least a year. “For mice, that’s quite a long time, almost a third of their life,” Wakim says. She doesn’t yet know why there’s a difference between nose and lung T cell memories, but finding out may enable researchers to boost lung T cell memory. Still, with nose T cells providing security, the lungs might not need much flu-fighting memory. Memory T cells that patrol only the upper respiratory tract could stop viruses from ever reaching the lungs, Wakim’s team found. An injection of virus under the skin didn’t produce any resident memory T cells in the respiratory tract. Those findings could mean that vaccines delivered via nasal spray instead of shots might stimulate memory T cell growth in the nose and could protect lungs from damage as well. A nasal spray called FluMist has had variable results in people. No one knows if that vaccine can produce nasal memory T cells. It’s not surprising to find that the nose has its own resident memory T cell security force, says Troy Randall, a pulmonary immunologist at the University of Alabama at Birmingham. “But it’s a good thing to know and certainly they’re the first to show it.”
The discovery may direct some research away from the lungs and toward the nose, Randall says. Future research should focus on how the resident memory T cells work with memory B cells that produce antibodies against viruses and bacteria, he suggests.
