Few space images are as iconic as those of the Horsehead Nebula. Its shape makes it instantly recognizable. Over the decades, a number of telescopes have captured its image, turning it into a sort of test case for a telescope’s power.
The JWST has them all beat.
The Horsehead Nebula is about 1300 light-years away in Orion. It’s part of the much larger Orion Molecular Cloud Complex. Horsehead is visible near the three stars in Orion’s Belt in a zoomed-in image.
The Horsehead Nebula is visible in this image of Orion’s Belt. It’s in the lower left, extending horizontally, to the lower left of the belt star Alnitak. Image Credit: By Davide De Martin (https://ift.tt/gS03tKh); Credit: Digitized Sky Survey, ESA/ESO/NASA FITS Liberator – https://ift.tt/4DW9Xgx (direct link), Public Domain, https://ift.tt/6nIBQbW
The leading image shows JWST’s view of the Horsehead Nebula alongside two other views. The Euclid image was captured in November 2023. Euclid features a wide-angle, 600-megapixel camera, and its primary job is to measure the redshift of galaxies and the Universe’s expansion due to dark energy. It took Euclid about one hour to capture the image, showcasing the telescope’s ability to gather highly detailed images quickly.
The Hubble captured its image in 2013 and was released as the telescope’s 23rd-anniversary featured image. The venerable Hubble does a good job of revealing structures hidden by dust. There’s nothing left to say about the Hubble that hasn’t been said already. It’s the revered elder among telescopes, and if you feel no reverence towards it, its contribution to science, and the people responsible for it, you may have a bad case of ennui.
The third image is a new one from the JWST’s NIRCam instrument. It’s described as the sharpest image of the Horsehead ever taken. It shows a small part of the iconic nebula in detail we don’t usually see. The JWST is so powerful it even shows background galaxies.
A zoom-in of the JWST image. The detail is incredible. Image Credit: ESA/Webb, CSA, K. Misselt, M. Zamani (ESA/Webb)
The Horsehead Nebula is the result of stellar erosion. The nebula itself was formed by a collapsing cloud of material, and a nearby hot star called Sigma Orionis illuminates the structure. The nebula is denser than its surrounding gas and has resisted the dissipative energy of the star, while the gas that used to surround it is long gone.
This definitely isn’t the last we’ll see of Horsehead. New, powerful telescopes coming online soon, like the Giant Magellan Telescope and the European Extremely Large Telescope will likely take a crack at the nebula. Prepare to be wowed.
There’s no rush. According to astronomers, the Horsehead Nebula will eventually be eroded away, too, but not for another five million years or so.
It stands to reason that stars formed from the same cloud of material will have the same metallicity. That fact underpins some avenues of astronomical research, like the search for the Sun’s siblings. But for some binary stars, it’s not always true. Their composition can be different despite forming from the same reservoir of material, and the difference extends to their planetary systems.
New research shows that the differences can be traced back to their earliest stages of formation.
Binary stars are the norm, while solitary stars like our Sun are in the minority. Some estimates place the number of binary stars in the Milky Way at up to 85%. These pairs of stars form from the same giant molecular clouds. Each cloud has a certain abundance of metals, and that abundance should be reflected in the stars themselves.
But that’s not always the case.
Sometimes, the metallicity of a pair of binary stars doesn’t agree. Astrophysicists have proposed three explanations for this.
Two explanations involve events occurring later in a star’s life after they’ve left the main sequence. One is atomic diffusion, where chemical elements settle into gradient layers in the star. The layers are determined by a star’s gravity and temperature. The second one involves a nearby planet. As stars age, expand, and become red giants, they engulf nearby planets. The planet would introduce new chemistry into the star, differentiating it from its binary partner.
As stars like our Sun age and leave the main sequence, they expand and become red giants, engulfing nearby planets. That can change the chemistry of the stars. Image Credit: fsgregs Creative Commons Attribution-Share Alike 3.0 Unported
The third explanation reaches back in time to the binary pair’s formation. This explanation says that the giant molecular cloud that spawned the stars wasn’t homogeneous. Instead, there were regional differences in the cloud’s chemistry, and stars formed in different locations showed noticeable differences in their chemical makeup.
A team of researchers wanted to dig into this third explanation to test its veracity. They used the Gemini South Telescope and its Gemini High-Resolution Optical SpecTrograph (GHOST) to examine the light from a pair of giant binary stars. The observations revealed significant differences in their spectra.
Sunset over Gemini South, on the summit of Mauna Kea in Hawai’i. Credit: Gemini
They presented their results in a paper titled “Disentangling the origin of chemical differences using GHOST.” It’s published in the journal Astronomy and Astrophysics. The lead author is Carlos Saffe of the Institute of Astronomical, Earth and Space Sciences (ICATE-CONICET) in Argentina. The researchers examined a pair of giant binary stars called HD 138202 + CD?30 12303.
The three explanations for chemical differences between binary stars all stem from studies of main sequence stars. The main sequence is where stars spend most of their time, reliably fusing hydrogen into helium for billions of years.
But Saffe and his colleagues took a different approach. They used Gemini and GHOST to examine a pair of binary stars that had left the main sequence behind and become giant stars. These stars are different from main sequence stars.
“GHOST’s extremely high-quality spectra offered unprecedented resolution,” said Saffe, “allowing us to measure the stars’ stellar parameters and chemical abundances with the highest possible precision.”
This table from the research shows some of the differences between the pair of giant binary stars. The third column shows their different metallicities, expressed by the Fe/H (iron hydrogen) ratio. The Star A is more metal-rich by ?0.08 dex than its companion. Image Credit: Saffe et al. 2024.
These stars experience dredge-ups. Dredge-ups are when a star’s convection zone extends from the surface all the way down to where fusion is taking place. They’re powerful convective currents that mix fusion products into the star’s surface layer when a main sequence star becomes a red giant.
This diagram of the Sun helps explain dredge-ups. The Sun is still on the main sequence, so its convective region is on its surface. But when stars like the Sun become red giants, temporary convective cells called dredge-ups can reach from the surface all the way to the fusion core. This can introduce different chemical elements onto the visible surface. Image Credit: CSIRO/ATNF/Naval Research Laboratory
However, the researchers say that dredge-ups and the atomic diffusion they drive can’t explain the wide difference between stars.
The convection currents would also rule out the second proposed explanation: planetary engulfment. With such strong currents, the chemicals from an engulfed planet would quickly be diluted. “Giant stars are thought to be significantly less sensitive than main-sequence stars to engulfment events,” the authors write.
The authors went further and calculated the amount of planetary material a giant star would need to digest to cause the difference in metallicity between the stars. “We estimate that star A would need to have ingested between 11.0 and 150.0 Jupiter masses of planetary material, depending on the adopted convective envelope mass and metallic content of the ingested planet,” the authors explain. That’s an awful lot of material. They also explain that the planets must have had extremely high metallicity for the low value of 11 Jupiter masses to cause the chemical differences.
That only leaves one explanation: inhomogeneities in the molecular cloud.
This is a two-panel mosaic of part of the Taurus Giant Molecular Cloud, the nearest active star-forming region to Earth. The darkest regions are where stars are being born. Research shows that small inhomogeneities in the cloud can produce binary stars with different metallicities. Image Credit: Adam Block /Steward Observatory/University of Arizona
“This is the first time astronomers have been able to confirm that differences between binary stars begin at the earliest stages of their formation,” said Saffe.
“Using the precision-measurement capabilities provided by the GHOST instrument, Gemini South is now collecting observations of stars at the end of their lives to reveal the environment in which they were born,” said Martin Still, NSF program director for the International Gemini Observatory. “This gives us the ability to explore how the conditions in which stars form can influence their entire existence over millions or billions of years.”
The results go a long way to explaining why a pair of binary stars can have differing compositions. But they reach even further than that. They also explain why a pair of binary stars can have such different planetary systems. “Different planetary systems could mean very different planets — rocky, Earth-like, ice giants, gas giants — that orbit their host stars at different distances and where the potential to support life might be very different,” said Saffe.
But the results also present a challenge. Astronomers use chemical tagging to identify stars that are associated with one another. Stars from the same stellar nursery are expected to have similar compositions. But that method seems unreliable in light of these findings.
The results also challenge the idea that differences in composition between binary stars can be explained by planet engulfment. Instead, those differences might stem from the stars’ earliest days of formation.
“By showing for the first time that primordial differences really are present and responsible for differences between twin stars, we show that star and planet formation could be more complex than initially thought,” said Saffe. “The Universe loves diversity!”
This artist’s concept shows a hypothetical planet covered in water around the binary star system of Kepler-35A and B. If differences in chemical compositions in stars stem from their earliest days of formation, then those differences must affect the types of planets that form around them. (Image by NASA/JPL-Caltech.)
The only drawback of this study is the sample size of one. Small sample sizes are always cautionary: they can lead to an eventual conclusion but don’t form reliable conclusions independently. The authors know this.
“We strongly encourage the study of giant-giant pairs,” the researchers conclude. “This novel approach might help us to distinguish the origin of the slight chemical differences observed in multiple systems.”
Has Earth always had this deflector shield? Probably so, and the evidence is in old rocks. A team of researchers at University of Oxford and MIT found the earliest evidence for its existence in stones found along the coast of Greenland in a region called the Isua Supercrustal Belt.
Geologists have long known that iron particles in rocks “entrain” a print of the magnetic field that was in place when they formed. So, the research team uncovered rocks that formed some 3.7 billion years ago. It’s not an easy task, according to team lead Claire Nichols of the Department of Earth Sciences at Oxford. “Extracting reliable records from rocks this old is extremely challenging,” Nichols pointed out. “It was really exciting to see primary magnetic signals begin to emerge when we analyzed these samples in the lab. This is a really important step forward as we try and determine the role of the ancient magnetic field when life on Earth was first emerging.”
This 3.7-billion-year-old rock from Greenland. Entrained magnetic field fingerprints help scientists determine that our magnetosphere and magnetic field existed when this rock formed. Courtesy: Claire Nichols.
The team’s samples recorded a magnetic field strength of 15 microteslas at the time they formed. Today, Earth’s field strength is closer to 30 microteslas, so it’s obvious that our magnetic field and magnetosphere have been there for billions of years. It’s also clear that the field changes over time. The science team also found that early Earth’s magnetosphere was amazingly similar to the one it has today.
Tracking Earth’s Magnetosphere through Time
Our planet has a main dynamo at its heart. There are two cores—an inner one and an outer one. Motions in the core regions generate the magnetic field that defines our magnetosphere. Molten iron mixes and moves in the fluid outer core and the inner core solidifies. The two actions together create that dynamo. That’s what’s happening inside our planet today.
This cutaway of planet Earth shows the familiar exterior of air, water and land as well as the interior: from the mantle down to the outer and inner cores. Currents in hot, liquid iron-nickel in the outer core create our planet’s protective but fluctuating magnetic field and magnetosphere. Credit: Kelvinsong / Wikipedia
However, when Earth was first forming some 4.5 billion years ago, that solid inner core didn’t exist. Without the interaction we see today between the two parts of the core, it’s hard to know how any early magnetic field existed. That’s an open question among geologists and planetary scientists: how did it form and how was it sustained?
Another question relates to how much the planetary magnetic field has varied over time. Answering that one would help geologists understand just when the solid inner core formed. It would also show how much heat has escaped our planet from deep inside over time. Heat escape drives plate tectonics, which uses large “plates” of rock to shift things around on the surface over hundreds of millions of years.
What Do the Rocks Tell Us?
Rocks have a long and complex history. They form as a molten mixture that solidifies, or in the case of sandstones, are laid down in layers that then harden. In the case of molten rocks, they have magnetic field fingerprints entrained at the time of formation. In measuring those fingerprints, geologists account for any heating that could “reset” the magnetic signatures over time. The Greenland rocks are relatively pristine, meaning they haven’t been significantly heated since they formed. That means their magnetic fingerprints haven’t changed since formation.
Lava cooling after an eruption. This rock has an entrained magnetic field fingerprint from the time it formed. Credit: kalapanaculturaltours.com
Rocks also get weathered by wind, temperature changes and erosion, but the Isuan samples seem to be relatively pristine, according to Benjamin Weiss of MIT. “Northern Isua has the oldest known well-preserved rocks on Earth,” Weiss said. “Not only have they not been significantly heated since 3.7 billion years ago but they have also been scraped clean by the Greenland ice sheet.”
Rocks Through Time
The rocks the team studied date back to the Archean Eon—the second-oldest geologic eon in Earth’s history. That period began about 4 billion years ago, and during that time Earth was largely an ocean world with a limited amount of continental surface. Since then, Earth’s surface has changed a great deal, destroying or burying rocks from earlier times. So, finding rocks that date back that far in time is a big deal.
The Isuan rocks are relatively unchanged since they formed, and bear proof of a magnetic field existing less than a billion years after the planet formed. That same early magnetic field could have played a role in the development of our planet’s atmosphere, by assisting in removing xenon gas. Other old rocks may well tell scientists more about the birth of the magnetic field. There are rocks in Canada, Australia and South Africa that could give unique insight into the formation of the field and its role in making Earth habitable for life.
When the first stars in the Universe formed, the only material available was primordial hydrogen and helium from the Big Bang. Astronomers call these original stars Population Three stars, and they were extremely massive, luminous, and hot stars. They’re gone now, and in fact, their existence is hypothetical.
But if they did exist, they should’ve left their fingerprints on nearby gas, and astrophysicists are looking for it.
The hunt for the Universe’s Population 3 (Pop III) stars is important in astrophysics. They were the first to form astronomical metals, elements heavier than hydrogen and helium. Only once these metals were available could rocky planets form. Their metals also fed into the next generation of stars, leading to the higher metallicity we observe in stars like our Sun.
Since Pop III stars were so massive and hot, they didn’t last long. None would have survived to this day. But the powerful JWST can expand the search for these crucial stars by looking back in time for their ancient light. That’s what the JWST-JADES (James Webb Space Telescope Advanced Deep Extragalactic Survey) is all about.
Researchers working with JADES data have found tantalizing evidence of Pop III stars in GN-z11, a high-redshift galaxy that’s one of the furthest galaxies from Earth ever observed. Their findings are in the paper “JWST-JADES. Possible Population III signatures at z=10.6 in the halo of GN-z11.” The lead author is Roberto Maiolino, a professor of Experimental Astrophysics at the Cavendish Laboratory (Department of Physics) and the Kavli Institute for Cosmology at the University of Cambridge. The research will be published in the journal Astronomy and Astrophysics.
“Finding the first generation of stars formed out of pristine gas in the early Universe, known as Population III (Pop III) stars, is one of the most important goals of modern astrophysics,” Maiolino and his colleagues write in their paper. “Recent models have suggested that Pop III stars may form in pockets of pristine gas in the halo of more evolved galaxies.”
GN-z11 is one such galaxy. At a redshift of z = 10.6034, the JWST sees the galaxy as it existed about 13.4 billion years ago, corresponding to about 400 million years after the Big Bang.
Pop III stars were massive and could be as much as 1000 times more massive than the Sun. These massive stars would’ve been exceptionally hot, which can provide a clue to their presence. Astrophysicists think all that heat could’ve doubly ionized nearby helium. So they search for the expected signature of that helium: prominent HeII nebular lines called the HeII?1640 emission line. To indicate the presence of Pop III stars, the HeII lines need to be unaccompanied by any metal lines.
The JWST observed the galaxy with its NIRSpec-IFU (Integrated Field Unit) and found a tentative detection of HeII?1640.
This figure from the research shows the detection of doubly-ionized Helium at 1.903 µm. in the galaxy GN-z11. Image Credit: Maiolino et al. 2024.
Detecting the doubly-ionized helium line was only the first step. Pop III stars aren’t the only objects that could’ve ionized the helium. To determine if the ancient stars were responsible, the researchers examined the galaxy and isolated several features.
Along with the HeII?1640, they also found Lyman-alpha emissions and CIII, or doubly-ionized carbon.
This figure from the research shows the detection of different emissions. The red star in the top images indicates the position of the continuum of GN-z11. The bottom row shows the lines mapped onto a JWST NIRCam image. The ‘fewer exposures’ on the top row indicates a lack of exposures in the upper portions of the panels due to a telescope-pointing error. Image Credit: Maiolino et al. 2024.
In the images above, the researchers note several features that are clues to the source of the helium ionization.
The HeII emissions show a plume extending to the west of GN-z11. It could be tracing gas photoionized by the galaxy’s active galactic nucleus (AGN.) Since CIII is so weak there, it could indicate very low metallicity gas photoionized by the AGN.
The image also shows a clump of HeII to the northeast of GN-z11. The researchers call this clump the “most intriguing” feature found. They analyzed the clump in the image below.
This figure from the research shows the spectra of the HeII clump. The observed emissions (blue) line up with the expected emissions from a galaxy at redshift z=10.600. Image Credit: Maiolino et al. 2024.
So what does this all add up to? Did the researchers find Pop III stars?
The spectral feature in the clump is strong evidence of photoionization by Pop III stars, according to the authors. “This wavelength corresponds to HeII?1640 at z=10.600, and it is fully consistent with the redshift of GN-z11,” they write. The same emission was detected over a larger area to the northeast, possibly with a second, fainter clump.
The authors say that the AGN could’ve photoionized the helium close to the galaxy’s center, but it can’t explain the HeII further away. Pop III stars are the best explanation, according to the authors.
Other evidence for Pop III stars comes from the emissions widths of the HeII lines. The high width suggests photoionization by metal poor Pop III stars rather than by Pop II stars with higher metallicity.
The extent of the ionization also indicates a certain mass for the Pop III stars, and the indicated mass agrees with simulations.
There’s another possibility: a direct collapse black hole (DCBH). “We also considered the alternative possibility of photoionization by a DCBH in the HeII clump,” the authors write. But the emission width should be lower in that scenario, although not by a lot. “Hence, this scenario remains another possible interpretation,” the authors write.
If future observations confirm the presence of Pop III stars in GN-z11, that’s a pretty big deal. But even if we have to wait for that confirmation, this research shows how powerful the JWST is again.
“These results have demonstrated the JWST’s capability to explore the primitive environment around galaxies in the early Universe, revealing fascinating properties,” the researchers conclude.
Anyone familiar with astronomy will know that galaxies come in a fairly limited range of shapes, typically; spiral, elliptical, barred-spiral and irregular. The barred-spiral galaxy has been known to be a feature of the modern universe but a study from astronomers using the Hubble Space Telescope has recently challenged that view. Following on observations using the James Webb Space Telescope has found the bar feature in some spiral galaxies as early as 11 billion years ago suggesting galaxies evolved faster in the early Universe than previously expected.
Our own Galaxy, the Milky Way is a spiral galaxy with a central nucleus and spiral arms emanating out from the centre. Our Solar System lies about 25,000 light years from the centre. Look at the galaxies in the sky though and you will see a real mix but generally they fall under the four main categories. Edwin Hubble tried to bring some structure to the different shapes by developing his galaxy classification scheme to articulate not only the shape but also the sub categories within them.
This research published in Nature is the first direct confirmation that supermassive black holes are capable of shutting down galaxies
It has been known for some time that galaxies aren’t static. They move and they evolve and change. Spiral galaxies for example, as they age, they often develop a bar feature. The bar joins up the spiral arms instead of a nucleus connecting them and it is believed they are temporary, forming when a build of gas creates a burst of star formation.
The existence of a bar in a spiral galaxy suggests that the galaxy is fairly stable. Understanding just how the bar feature forms is key to understanding the evolutionary process of the galaxy itself. All previous observations showed that the appearance of the bar significantly reduces from the nearby Universe to redshifts near a value of one. This tells us that the bar seemed to be a modern feature and not present in the early Universe.
The barred spiral galaxy NGC 1300. Credit: NASA, ESA, and The Hubble Heritage Team (STScI/AURA)
In a new paper by lead author Zoe A Le Conte, observations from the more sensitive James Webb Space Telescope report that galaxies to greater redshift are studied for bar features. Data is used from the Cosmic Evolution Early Release Science Survey and the observations from the Public Release Imaging for Extragalactic Research studies. Only the galaxies that also appear in the Cosmic Assembly Near Infra Red Deep Extragalactic Legacy Survey are used giving a sample of 368 face on galaxies.
The team visually searched through the 368 galaxy selection to classify and identify those with bars between redshifts 1 and 2 and then repeated the exercise for those between redshift 2 and 3. As expected, the fraction of bars reduced from around 17.8% between a red shift of 1 and 2 down to 13.8% at the greater red shift of 2 to 3.
The study revealed that JWST’s infra-red sensitivity picked up twice as many barred-spiral galaxies than the HST’s more blue sensitive imaging platform. Le Conte and her team conclude that the evolution of bars in spiral galaxies began to appear at a much earlier epoch, around 11 billion years ago.
When a spacecraft arrives at its destination, it settles into an orbit for science operations. But after the primary mission is complete, there might be other interesting orbits where scientists would like to explore. Maneuvering to a different orbit requires fuel, limiting a spacecraft’s number of maneuvers.
Researchers have discovered that some orbital paths allow for no-fuel orbital changes. But the figuring out these paths also are computationally expensive. Knot theory has been shown to find these pathways more easily, allowing the most fuel-efficient routes to be plotted. This is similar to how our GPS mapping software plots the most efficient routes for us here on Earth.
In mathematics, knot theory is the study of closed curves in three dimensions. Think of it as looking at a knotted necklace or a tangle of fishing line, and figuring out how to untangle them in the most efficient manner.
In the same way, a spacecraft’s path could be computed in a crowded planetary system – around Jupiter and all its moons, for example – where the best, simplest and least tangled route could be computed mathematically.
A graphic showing the orbital path the Danuri Lunar Pathfinder spacecraft will take to go into orbit around the Moon. Credit: Korea Aerospace Research Institute (KARI)
“Previously, when the likes of NASA wanted to plot a route, their calculations relied on either brute force or guesswork,” said Danny Owen, a postgraduate research student in astrodynamics, in a press release from the University of Surrey. “Our new technique neatly reveals all possible routes a spacecraft could take from A to B, as long as both orbits share a common energy level.”
Owen added that this new process makes the task of planning missions much simpler. “We think of it as a tube [subway] map for space,” he said.
Spacecraft navigation is complicated by the fact that nothing in space is a fixed position. Navigators must meet the challenges of calculating the exact speeds and orientations of a rotating Earth, a rotating target destination, as well as a moving spacecraft, while all are simultaneously traveling in their own orbits around the Sun.
Since fuel is a limited resource for most missions, it would be beneficial to require the least amount of fuel possible in making any changes to the course of a spacecraft in orbit.
Spacecraft navigators use something called heteroclinic orbits — often called heteroclinic connections — which are paths that allow a spacecraft to travel from one orbit to another using the most efficient amount of fuel – or sometimes no fuel at all. But this usually takes a large amount of computer power or a lot of time to figure out.
Artist’s impession of the Lunar Gateway with the Orion spacecraft docked on the left side. Credit: ESA
But Owen and co-author Nicola Baresi, a lecturer in Orbital Mechanics at the University of Surrey, wrote that by using knot theory, they have developed “a method of robustly detecting heteroclinic connections,” they wrote in their paper, to quickly generate rough trajectories – which can then be refined. This gives spacecraft navigators a full list of all possible routes from a designated orbit, and the one that best fits the mission can be chosen. They can then choose the one that best suits their mission.
The researchers tested their technique on various planetary systems, including the Moon, and the Galilean moons of Jupiter.
“Spurred on by NASA’s Artemis program, the new Moon race is inspiring mission designers around the world to research fuel-efficient routes that can better and more efficiently explore the vicinity of the Moon,” said Baresi. “Not only does our technique make that cumbersome task more straightforward, but it can also be applied to other planetary systems, such as the icy moons of Saturn and Jupiter.”
The list of chemicals found in space is growing longer and longer. Astronomers have found amino acids and other building blocks of life on comets, asteroids, and even floating freely in space. Now, researchers have found another complex chemical to add to the list.
The new chemical is known as 2-methoxyethanol (CH3OCH2CH2OH). It’s one of several methoxy molecules that scientists have found in space. But with 13 atoms, it’s one of the largest and most complex ones ever detected.
A team of scientists called the McGuire Group specializes in detecting chemicals in space. The McGuire Group and other researchers from institutions in Florida and France worked together to find 2-methoxyethanol.
A ball and stick model of 2-methoxyethanol (CH3OCH2CH2OH). With 13 atoms, it’s one of the largest complex chemicals ever found in space. Image Credit: By Ben Mills – Own work, Public Domain, https://ift.tt/pkOA8Vy
“There are a number of ‘methoxy’ molecules in space, like dimethyl ether, methoxymethanol, ethyl methyl ether, and methyl formate, but 2-methoxyethanol would be the largest and most complex ever seen,” said lead author Fried.
The researchers didn’t stumble upon the large molecule. It was found as part of a concerted effort to detect new chemicals in space. It all started with machine learning. In 2023, one machine-learning model suggested they look for 2-methoxyethanol. The next step was the lab, where researchers performed experiments that measured and analyzed the molecule’s rotational spectrum here on Earth.
“We do this by looking at the rotational spectra of molecules, the unique patterns of light they give off as they tumble end-over-end in space,” said Fried. “These patterns are fingerprints (barcodes) for molecules. To detect new molecules in space, we first must have an idea of what molecule we want to look for, then we can record its spectrum in the lab here on Earth, and then finally we look for that spectrum in space using telescopes.”
The researchers measured the molecule’s spectrum over a broadband region of frequencies ranging from the microwave to sub-millimetre wave regimes (from about 8 to 500 gigahertz).
With that data in hand, the researchers turned to ALMA, the Atacama Large Millimetre/sub-millimetre Array. ALMA gathered data from two star-forming regions: NGC 6334I and IRAS 16293-2422B. Researchers from the McGuire Group, the National Radio Astronomy Observatory, and the University of Copenhagen all worked on analyzing ALMA’s observations.
“Ultimately, we observed 25 rotational lines of 2-methoxyethanol that lined up with the molecular signal observed toward NGC 6334I (the barcode matched!), thus resulting in a secure detection of 2-methoxyethanol in this source,” said Fried. “This allowed us to then derive physical parameters of the molecule toward NGC 6334I, such as its abundance and excitation temperature. It also enabled an investigation of the possible chemical formation pathways from known interstellar precursors.”
NGC 6334m the Cat’s Paw Nebula. Image Credit: ESO
Here on Earth, 2-methoxyethanol is used mostly as a solvent. It’s toxic to bone marrow and testicles. But its status here on Earth isn’t relevant to its discovery.
The large molecule isn’t a building block for life, either. It’s significant because of its size and complexity. Scientists are interested in understanding how chemistry evolves and forms large molecules in regions where stars and planets are forming.
“Our group tries to understand what molecules are present in regions of space where stars and solar systems will eventually take shape,” explained Fried. “This allows us to piece together how chemistry evolves alongside the process of star and planet formation.”
Molecular complexity is the hallmark of life, so, of course, scientists want to understand molecular complexity in space. As of 2021, scientists only found six molecules in space larger than 13 atoms outside our Solar System. McGuire’s team found many of them.
Finding them is the first step. The next step is to figure out how and where they form. Though there are no direct links between 2-methoxyethanol and life, all complex chemistry has something to tell us about complex chemistry in general.
“Continued observations of large molecules and subsequent derivations of their abundances allows us to advance our knowledge of how efficiently large molecules can form and by which specific reactions they may be produced,” said Fried. “Additionally, since we detected this molecule in NGC 6334I but not in IRAS 16293-2422B, we were presented with a unique opportunity to look into how the differing physical conditions of these two sources may be affecting the chemistry that can occur.”
IRAS 16293?2422 in the star-forming region Rho Ophiuchi. Image Credit: ESO
NGC 6334I is a higher-mass star-forming region compared to IRAS 16293-2422B. That means it could have a potentially enhanced radiation field. That enhanced radiation could produce more precursors for 2-methoxyethanol, eventually leading to more of the molecule itself. Warmer dust temperatures may have contributed, too. Warmer dust allows greater dust mobility, leading to chemical fragments being allowed to recombine.
Thanks to ever-improving observational tools and methods, including machine learning, astrochemistry is a blossoming field. If we’re ever going to understand how life on Earth arose and where it may likely rise elsewhere in the galaxy, astrochemistry will play a leading role. Though 2-methoxyethanol isn’t directly related to life, its detection still tells scientists something.
Brown dwarfs span the line between planets and stars. By definition, a star must be massive enough for hydrogen fusion to occur within its core. This puts the minimum mass of a star around 80 Jupiters. Planets, even large gas giants like Jupiter, only produce heat through gravitational collapse or radioactive decay, which is true for worlds up to about 13 Jovian masses. Above that, deuterium can undergo fusion. Brown dwarfs lay between these two extremes. The smallest brown dwarfs resemble gas planets with surface temperatures similar to Jupiter. The largest brown dwarfs have surface temperatures around 3,000 K and look essentially like stars.
Because of this, it can be difficult to study brown dwarfs, particularly ones that don’t orbit other stars. Without much reflected or emitted light, we can’t easily analyze their spectra to determine their composition. Fortunately, some brown dwarfs do emit radio light thanks to their strong magnetic fields.
Planets such as Earth and Jupiter have strong magnetic fields, and this means they can trap ionized particles such as hydrogen. These charged particles then spiral along the magnetic field lines until they collide with the planet’s upper atmosphere, generating glowing aurora. On Earth, we see them as the Northern Lights. For brown dwarfs, we can’t see the visible light of their aurora, but we can detect their radio glow.
Recently a team looked at the auroral light from a brown dwarf known as W1935. It is a cold brown dwarf 47 light-years from Earth with a surface temperature of just 200 °C. Within the spectra the team found light emissions from methane. While the presence of methane was expected in cold brown dwarfs, the fact that the methane emitted light was not. This means the atmosphere of W1935 likely has a thermal inversion, where the upper atmosphere is warmer than the lower layers.
This is true for the atmosphere of Earth but is driven by solar radiance. W1935 doesn’t orbit a star, so how can its upper atmosphere get so warm? One possible explanation is that the brown dwarf has an undetected small companion. This companion could be ejecting material similar to the way Saturn’s moon Enceleadus ejects water vapor. Once ionized in the vacuum of space, it would become trapped by the magnetic fields of W1935, eventually colliding with the brown dwarf’s upper atmosphere and giving it a bit of thermal heating.
This discovery shows that even the smallest brown dwarfs defy easy classification. Though they resemble planets, they may have their own planetary system like a star.
Life on Earth would not be possible without food, water, light, a breathable atmosphere and surprisingly, a magnetic field. Without it, Earth, and its inhabitants would be subjected to the harmful radiation from space making life here, impossible. If we find exoplanets with similar magnetospheres then those worlds may well be habitable. The Square Kilometer Array (SKA) which is still under construction should be able to detect such magnetospheres from radio emissions giving us real insight into our exoplanet cousins.
The magnetic field of Earth is the result of churning motion of liquid iron and nickel in the outer core. The resultant magnetic field has properties of a giant magnet with a north pole and a south pole and it extends from the core outward, enveloping the entire planet. The presence of the field stops harmful solar radiation and cosmic particles. Magnetic fields are not static though and it is not uncommon for them to flip, as has happened to our own magnetic field.
Since we have been hunting exoplanets (and to date, over 5,000 have been discovered) it has become clear that there are a good number of super sized gas gas giants. As our detection technology and methods improve, smaller, more Earth like planets are starting to be discovered. It is therefore not unreasonable to think that, among them, there may well be alien planets with magnetic fields making them, therefore good candidates for habitable environments.
Artist impression of glory on exoplanet WASP-76b. Credit: ESA
Understanding exoplanet magnetic fields is in its infancy. So far, we have only explored magnetic fields around the planets in our Solar System. What we do know is that any planetary magnetic field emits radio signals due to the Electron Cyclotron Maser Instability mechanism. Sounds like something out of StarTrek or StarWars depending on your preference but either way, electromagnetic radiation is amplified by electrons that are trapped in the field. It is this amplified radiation that can be detected remotely IF we have a radio telescope with the capability.
A recent paper authored by Fatemeh Bagheri and team from the University of Texas explores whether it might be possible to detect the emissions using the Square Kilometre Array. The concept of the SKA is a radio interferometer with components in Australia and Africa and its headquarters in the UK. The international array of radio telescopes that are joined together electronically to operate as one collecting area of a square kilometre. It affords the ability to study the radio sky with higher sensitivity and resolution than ever before and it’s this, that Bagheri and team are focusing their attention.
Aerial image of the South African MeerKAT radio telescope, part of the Square Kilometer Array (SKA). Credit: SKA
Using NASA’s exoplanet archive data, they calculated the strength of radio signal from 80 confirmed planets. They took the planet’s radius, mass and orbital distance from the host star, along with the stars’ mass, radius and distance form us to estimate the signal from the magnetosphere. The results were promising and suggest that, according to their analysis exoplanets; Qatar-4 b, TOI-1278 b, and WASP-173 A b would indeed emit radio signals from their magnetosphere that the SKA could detect. Unfortunately we will have to wait until 2028 when SKA is operational but already, it seems researchers are lining up to use it and this piece of research in particular looks set not only to herald a greater understanding of exoplanets but also the possibility of life in the Universe.
When I heard about this I felt an amused twinge of envy. Over the last year I have been using an unimpressive 4G broadband service and at best get 20 Mbps, NASA’s Psyche mission has STILL been getting 23 Mbps at 225 million km away! It’s all thanks to the prototype optical transmission system employed on the probe. It means it can get up to 100 times more data transmission rate than usual radio.
NASA’s Pysche mission is on its way to explore the metal rich asteroid between the orbits of Mars and Jupiter called, not surprisingly Psyche. The intriguing thing about the asteroid is that it seems to be the iron rich core of an unformed planet. The spacecraft carried a wealth of scientific instruments to explore the asteroid including an imaging rig, gamma ray and neutron spectrometer, magnetometer and an X-band Gravity platform.
It began its two year journey on 13 October with its destination, a tiny world that may help us unravel some of the mysteries of the formation of our Solar System. The theory that Psyche is a failed planetary core is not certain so this will be one of the first of its mission objectives; is it simply unmelted metal or was it a core. In order to understand this it’s necessary to work out its age. Secondary to the origin, other objectives are to explore the composition and its topography across the surface.
Asteroid Psuche was discovered in March 1852 by Italian astronomer Annibale de Gasparis. Because he discovered it, he was allowed to name it and settled on Psyche after the Greek goddess of the soul. It orbits the Sun at a distance of between 378 million to 497 million kilometres and takes about 5 Earth years to complete an orbit. Shaped like a potato, or perhaps more accurately classed as ‘irregular’ it is actually a little ellipsoid in shape measuring 280 km across wide at its widest part and 232 km across long.
Illustration of the metallic asteroid Psyche. Credit: Peter Rubin/NASA/JPL-Caltech/ASU
Of more interest than the objectives perhaps (although I for one am looking forward to learn more about this wonderful asteroid) was the trial communication system. The newly developed Deep Space Optical Communications technology (DSOC) is not the primary communications platform but it is there as a prototype.
The optical system which relies upon laser technology successfully sent back engineering data at a distance of 226 million kilometres. Perhaps more impressively though, the spacecraft has shown that it can transmit at a rate of 267 Mbps (YES you read that right, just over quarter of a Gbps!) The impressive download speed was achieved on 11 December last year when a 15 second ultra high definition video was sent to Earth. Sadly though, as the spacecraft recedes, its data transmission capability will reduce. Still far better than normal radio communications though.
Using a powerful modulated laser, the Optical Communication Telescope Laboratory in California will be able to send data at a low rate to Psyche. To receive data, a photon counting receiver has been installed at the Caltech Palomar Observatory to pickup information sent by the spacecraft. Communication has always been a great challenge in space exploration and, whilst we cannot reduce transit time for data, we can improve the amount of data sent at any one time. A great step forward in space exploration.
The Hubble Space Telescope has gone through its share of gyroscopes in its 34-year history in space. Astronauts replaced the gyros during the last servicing mission in 2009, bringing it back up to six (three with three spares), but they only last so long. Last week, HST went into safe mode because one of the gyros experienced fluctuations in power. NASA paused the telescope’s science operations today to investigate the fluctuations and perhaps come up with a fix.
With this one gyro experiencing problems, only two of the gyros remain fully operational. HST works best with three gyros, and so engineers are working to understand the issue and hopefully figure out a way to fix it remotely. However, several years ago, engineers figured out a way to still conduct science operations with only a single gyro.
HST entered safe mode on April 23, 2024 when the one gyro sent faulty readings. This particular gyro also caused Hubble to enter safe mode last November after returning similar faulty readings. The gyroscopes are part of Hubble’s Pointing Control System, which includes three Fine Guidance Sensors, reaction wheels and the gyros. This allows Hubble to track stars with incredible accuracy, helping the telescope find its way as it scans the heavens, as well as keep Hubble locked onto to its targets.
To work correctly, Hubble must be able to stay focused on a target without deviating more than 7/1000th of an arcsecond, or about the width of a human hair seen at a distance of a mile.
Hubble team created a contingency plan in preparation for a time when the spacecraft might find itself with less than three working gyros again. The team developed a two-gyro mode that substitutes other sensors for one missing gyro. Although less efficient, two-gyro mode allows Hubble to continue collecting ground-breaking science data.
The end of a Hubble gyro reveals the hair-thin wires known as flex leads. They carry data and electricity inside the gyro. Credit: NASA
NASA said that Hubble gyros fail over time, usually because of “wear and tear” of thin (less than the width of a human hair), metal wires, called flex leads that carry power in, and data out, of the mechanism. Hubble’s flex leads pass through a thick fluid inside the gyro. Over time, the flex leads begin to corrode and can physically bend or break.
During its 34-year history, Hubble has had eight out of 22 gyros fail due to a corroded flex lead. For example, in 1999, four out of six gyros had failed, with the last one failing about a month before a servicing mission was scheduled to replace them (and do other upgrades to the telescope). This meant Hubble sat in safe mode waiting for the space shuttle and astronauts to arrive.
Engineers developed a two-gyro mode when the final planned Hubble servicing mission was (temporarily) canceled following the space shuttle Columbia disaster. The mission was reinstated after outcry from scientists and the public, and so NASA figured out a way to mitigate the risks of flying the space shuttle. Servicing Mission 4 replaced all six gyros one last time in 2009.
With his feet firmly anchored on the shuttle’s robotic arm, astronaut Mike Good maneuvers to retrieve the tool caddy required to repair the Space Telescope Imaging Spectrograph during the final Hubble servicing mission in May 2009. Periodic upgrades have kept the telescope equipped with state-of-the-art instruments, which have given astronomers increasingly better views of the cosmos. Credits: NASA
However, during the time it was thought no future servicing mission would happen, the observatory was proactively put into two-gyro mode to prolong its life. During this time, the team also devised a one-gyro mode, which could further extend Hubble’s life if needed.
“We knew gyros would be a limiting factor so we started to working on a reduced gyro mode to extend their life,” the director of the Space Telescope Science Institute Ken Sembach told me back in 2015 for my book, “Incredible Stories From Space.” “As it turned out, we did need that reduced gyro mode, and now they aren’t [as big of a] limiting factor for Hubble because we now know how to use the gyro resources in a new way. That added a longer life to the mission we didn’t think we would have.”
While the difference between two-gyro mode and one gyro-mode is negligible, one-gyro mode provides the option to have one of the remaining gyros placed in reserve. As of now, three of the six gyros onboard Hubble have had a flex lead fail and are no longer functional. NASA has not announced if the faulty readings are due to flex lead fail or another issue. If this gyro fails, the team will invoke one-gyro mode.
NASA did say that all of the science instruments are in good shape and they anticipate Hubble will “continue making groundbreaking discoveries, working with other observatories throughout this decade and possibly into the next.”
Hubble launched in 1990, and recently celebrated its 34th anniversary. While everyone expected HST would revolutionize astronomy, I don’t think anyone expected it would continue to be such a productive, world-class observatory even more than a thirty years after it launched. But, please, let’s keep it going for as long as possible!
Any event in the cosmos generates gravitational waves, the bigger the event, the more disturbance. Events where black holes and neutron stars collide can send out waves detectable here on Earth. It is possible that there can be an event in visible light when neutron stars collide so to take advantage of every opportunity an early warning is essential. The teams at LIGO-Virgo-KAGRA observatories are working on an alert system that will alert astronomers within 30 seconds fo a gravity wave event. If warning is early enough it may be possible to identify the source and watch the after glow.
The very fabric of space-time can be thought of as a giant celestial ocean. Any movement within the ocean will generate waves. The same is true of movements and disturbances in space, causing a compression in one direction while stretching out in the perpendicular direction. Modern gravity wave detectors are usually L-shaped with beams shining down each arm of the building. The two beams are combined and the interference patterns are studied allowing the lengths of the two beams to be accurately calculated. Any change suggests the passage of a gravity wave.
LIGO Observatory
A team of researchers at the University of Minnesota have run a study that endeavours to improve the detection of the waves. Not only do they hope to improve the detection itself but also to establish an alerting mechanism so that astronomers get a notification within 30 seconds after the event detection.
The team used data from previous observations and created simulated gravity wave signal data so that they could test the system. But it is far more than just an alerting system. Once fully operational, it will be able to detect the shape of the signals, track how it evolves over time and even provide an estimate of the properties of the individual components that led to the waves.
After it is fully operational, the software would detect the wave for example from neutron star or black hole collisions. The former usually too faint to be able to detect unless its location is known precisely. It would generate an alert from the wave to help precisely pinpoint the location giving an opportunity for follow up study.
Light bursts from the collision of two neutron stars. Credit: NASA’s Goddard Space Flight Center/CI Lab
There are still many outstanding questions surrounding neutron star and black hole formation not least of which is the exact mechanism that leads to the formation of gold and uranium.
graThe LIGO (Laser Interferometer Gravitational-Wave Observatory) has just finished its latest run but the next is due in February 2025. Between recent observing runs, enhancements and improvements have been made to improve the capability of detecting signals. Eventually of course it comes down to the data and once the current run ends, the teams will get started.
The Milky Way has a missing pulsar problem in its core. Astronomers have tried to explain this for years. One of the more interesting ideas comes from a team of astronomers in Europe and invokes dark matter, neutron stars, and primordial black holes (PBHs).
Astronomer Roberto Caiozzo, of the International School for Advanced Studies in Trieste, Italy, led a group examining the missing pulsar problem. “We do not observe pulsars of any kind in this inner region (except for the magnetar PSR J1745-2900),” he wrote in an email. “This was thought to be due to technical limitations, but the observation of the magnetar seems to suggest otherwise.” That magnetar orbits Sagittarius A*, the black hole at the core of the Milky Way.
An x-ray map of the core of the Milky Way showing the position of the recently discovered magnetar orbiting the supermassive black hole Sgr A*. Courtesy Chandra and XMM-Newton.
The team examined other possible reasons why pulsars don’t appear in the core and looked closely at matnetar formation as well as disruptions of neutron stars. One intriguing idea they examined was the cannibalization of primordial black holes by neutron stars. The team explored the missing-pulsar problem by asking the question: could neutron star-primordial black hole cannibalism explain the lack of detected millisecond pulsars in the core of the Milky Way? Let’s look at the main players in this mystery to understand if this could happen.
Neutron Stars, Pulsars, and Little Black Holes, Oh My
Theory suggests that primordial black holes were created in the first seconds after the Big Bang. “PBHs are not known to exist,” Caiozzo points out, “but they seem to explain some important astrophysical phenomena.” He pointed at the idea that supermassive black holes seemed to exist at very early times in the Universe and suggested that they could have been the seeds for these monsters. If there are PHBs out there, the upcoming Nancy Grace Roman Telescope could help find them. Astronomers predict they could exist in a range of masses, ranging from the mass of a pin to around 100,000 the mass of the Sun. There could be an intermediate range of them in the middle, the so-called “asteroid-mass” PBHs. Astronomers suggest these last ones as dark matter candidates.
Primordial black holes, if they exist, could have formed by the collapse of overdense regions in the very early universe. Credit M. Kawasaki, T.T. Yanagida.
Dark matter makes up about 27 percent of the Universe, but beyond suggesting that PBH could be part of the dark matter content, astronomers still don’t know exactly what it is. There does seem to be a large amount of it in the core of our galaxy. However, it hasn’t been directly observed, so its presence is inferred. Is it bound up in those midrange PBHs? No one knows.
The third player in this missing pulsar mystery is neutron stars. They’re huge, quivering balls of neutrons left over after the death of a supergiant star of between 10 and 25 solar masses. Neutron stars start out very hot (in the range of ten million K) and cool down over time. They start out spinning very fast and they do generate magnetic fields. Some emit beams of radiation (usually in radio frequencies) and as they spin, those beams appear as “pulses” of emission. That earned them the nickname “pulsar”. Neutron stars with extremely powerful magnetic fields are termed “magnetars”.
Pulsars are fast-spinning neutron stars that emit narrow, sweeping beams of radio waves. A new study identifies the origin of those radio waves. NASA’s Goddard Space Flight Center
The Missing Pulsar Problem
Astronomers have searched the core of the Milky Way for pulsars without much success. Survey after survey detected no radio pulsars within the inner 25 parsecs of the Galaxy’s core. Why is that? Caizzo and his co-authors suggested in their paper that magnetar formation and other disruptions of neutron stars that affect pulsar formation don’t exactly explain the absence of these objects in the galactic core. “Efficient magnetar formation could explain this (due to their shorter lifetime),” he said, “But there is no theoretical reason to expect this. Another possibility is that the pulsars are somehow disrupted in other ways.”
Usually, disruption happens in binary star systems where one star is more massive than the other and it explodes as a supernova. The other star may or may not explode. Something may kick it out of the system altogether. The surviving neutron star becomes a “disrupted” pulsar. They aren’t as easily observed, which could explain the lack of radio detections.
If the companion isn’t kicked out and later swells up, its matter gets sucked away by the neutron star. That spins up the neutron star and affects the magnetic field. If the second star remains in the system, it later explodes and becomes a neutron star. The result is a binary neutron star. This disruption may help explain why the galactic core seems to be devoid of pulsars.
Using Primordial Black Hole Capture to Explain Missing Pulsars
Caizzo’s team decided to use two-dimensional models of millisecond pulsars—that is, pulsars spinning extremely fast—as a way to investigate the possibility of primordial black hole capture in the galactic core. The process works like this: a millisecond pulsar interacts in some way with a primordial black hole that has less than one stellar mass. Eventually, the neutron star (which has a strong enough gravitational pull to attract the PBH) captures the black hole. Once that happens, the PBH sinks to the core of the neutron star. Inside the core, the black hole begins to accrete matter from the neutron star. Eventually, all that’s left is a black hole with about the same mass as the original neutron star. If this occurs, that could help explain the lack of pulsars in the inner parsecs of the Milky Way.
Could this happen? The team investigated the possible rates of capture of PBHs by neutron stars. They also calculated the likelihood that a given neutron star would collapse and assessed the disruption rate of pulsars in the galactic core. If not all the disrupted pulsars are or were part of binary systems, then that leaves neutron star capture of PBHs as another way to explain the lack of pulsars in the core. But, does it happen in reality?
Missing Pulsar Tension Continues
It turns out that such cannibalism cannot explain the missing pulsar problem, according to Caizzo. “We found that in our current model PBHs are not able to disrupt these objects but this is only considering our simplified model of 2 body interactions,” he said. It doesn’t rule out the existence of PHBs, only that in specific instances, such capture isn’t happening.
So, what’s left to examine? If there are PHBs in the cores and they’re merging, no one’s seen them yet. But, the center of the Galaxy is a busy place. A lot of bodies crowd the central parsecs. You have to calculate the effects of all those objects interacting in such a small space. That “many-body dynamics” problem has to account for other interactions, as well as the dynamics and capture of PBHs.
Astronomers looking to use PBH-neutron star mergers to explain the lack of pulsar observations in the core of the Galaxy will need to better understand both the proposed observations and the larger populations of pulsars. The team suggests that future observations of old neutron stars close to Sgr A* could be very useful. They’d help set stronger limits on the number of PBHs in the core. In addition, it would be useful to get an idea of the masses of these PBHs, since those on the lower end (asteroid-mass types) could interact very differently.
