SPACE
Parker Solar Probe flies into the fast solar wind and finds its source
NASA probe got close enough to sun's surface to see hidden granular features
Peer-Reviewed PublicationIMAGE: ARTIST’S CONCEPT OF THE PARKER SOLAR PROBE SPACECRAFT APPROACHING THE SUN. LAUNCHED IN 2018, THE PROBE IS INCREASING OUR ABILITY TO FORECAST MAJOR SPACE-WEATHER EVENTS THAT IMPACT LIFE ON EARTH. view more
CREDIT: NASA
NASA's Parker Solar Probe (PSP) has flown close enough to the sun to detect the fine structure of the solar wind close to where it is generated at the sun's surface, revealing details that are lost as the wind exits the corona as a uniform blast of charged particles.
It's like seeing jets of water emanating from a showerhead through the blast of water hitting you in the face.
In a paper to be published this week in the journal Nature, a team of scientists led by Stuart D. Bale, a professor of physics at the University of California, Berkeley, and James Drake of the University of Maryland-College Park, report that PSP has detected streams of high-energy particles that match the supergranulation flows within coronal holes, which suggests that these are the regions where the so-called "fast" solar wind originates.
Coronal holes are areas where magnetic field lines emerge from the surface without looping back inward, thus forming open field lines that expand outward and fill most of space around the sun. These holes are usually at the poles during the sun's quiet periods, so the fast solar wind they generate doesn't hit Earth. But when the sun becomes active every 11 years as its magnetic field flips, these holes appear all over the surface, generating bursts of solar wind aimed directly at Earth.
Understanding how and where the solar wind originates will help predict solar storms that, while producing beautiful auroras on Earth, can also wreak havoc with satellites and the electrical grid.
“Winds carry lots of information from the sun to Earth, so understanding the mechanism behind the sun’s wind is important for practical reasons on Earth,” Drake said. “That’s going to affect our ability to understand how the sun releases energy and drives geomagnetic storms, which are a threat to our communication networks.”
Based on the team's analysis, the coronal holes are like showerheads, with roughly evenly spaced jets emerging from bright spots where magnetic field lines funnel into and out of the surface of the sun. The scientists argue that when oppositely directed magnetic fields pass one another in these funnels, which can be 18,000 miles across, the fields often break and reconnect, slinging charged particles out of the sun.
"The photosphere is covered by convection cells, like in a boiling pot of water, and the larger scale convection flow is called supergranulation," Bale said. "Where these supergranulation cells meet and go downward, they drag the magnetic field in their path into this downward kind of funnel. The magnetic field becomes very intensified there because it's just jammed. It's kind of a scoop of magnetic field going down into a drain. And the spatial separation of those little drains, those funnels, is what we're seeing now with solar probe data."
Based on the presence of some extremely high-energy particles that PSP has detected — particles traveling 10 to 100 times faster than the solar wind average — the researchers conclude that the wind could only be made by this process, which is called magnetic reconnection. The PSP was launched in 2018 primarily to resolve two conflicting explanations for the origin of the high-energy particles that comprise the solar wind: magnetic reconnection or acceleration by plasma or Alfvén waves.
"The big conclusion is that it's magnetic reconnection within these funnel structures that's providing the energy source of the fast solar wind," Bale said. "It doesn't just come from everywhere in a coronal hole, it's substructured within coronal holes to these supergranulation cells. It comes from these little bundles of magnetic energy that are associated with the convection flows. Our results, we think, are strong evidence that it's reconnection that's doing that."
The funnel structures likely correspond to the bright jetlets that can be seen from Earth within coronal holes, as reported recently by Nour Raouafi, a co-author of the study and the Parker Solar Probe project scientist at the Applied Physics Laboratory at Johns Hopkins University. APL designed, built, manages and operates the spacecraft.
Plunging into the sun
By the time the solar wind reaches Earth, 93 million miles from the sun, it has evolved into a homogeneous, turbulent flow of roiling magnetic fields intertwined with charged particles that interact with Earth's own magnetic field and dump electrical energy into the upper atmosphere. This excites atoms, producing colorful auroras at the poles, but has effects that trickle down into Earth's atmosphere. Predicting the most intense winds, called solar storms, and their near-Earth consequences is one mission of NASA's Living With a Star program, which funded PSP.
The probe was designed to determine what this turbulent wind looks like where it's generated near the sun's surface, or photosphere, and how the wind's charged particles — protons, electrons and heavier ions, primarily helium nuclei — are accelerated to escape the sun's gravity.
To do this, PSP had to get closer than 25 to 30 solar radii, that is, closer than about 13 million miles.
"Once you get below that altitude, 25 or 30 solar radii or so, there's a lot less evolution of the solar wind, and it's more structured — you see more of the imprints of what was on the sun," Bale said.
In 2021, PSP's instruments recorded magnetic field switchbacks in the Alfvén waves that seemed to be associated with the regions where the solar wind is generated. By the time the probe reached about 12 solar radii from the surface of the sun — 5.2 million miles — the data were clear that the probe was passing through jets of material, rather than mere turbulence. Bale, Drake and their colleagues traced these jets back to the supergranulation cells in the photosphere, where magnetic fields bunch up and funnel into the sun.
But were the charged particles being accelerated in these funnels by magnetic reconnection, which would slingshot particles outward, or by waves of hot plasma — ionized particles and magnetic field — streaming out of the sun, as if they're surfing a wave?
The fact that PSP detected extremely high-energy particles in these jets — tens to hundreds of kiloelectron volts (keV), versus a few keV for most solar wind particles — told Bale that it has to be magnetic reconnection that accelerates the particles and generates the Alfvén waves, which likely give the particles an extra boost.
"Our interpretation is that these jets of reconnection outflow excite Alfvén waves as they propagate out," Bale said. "That's an observation that's well known from Earth's magnetotail, as well, where you have similar kind of processes. I don't understand how wave damping can produce these hot particles up to hundreds of keV, whereas it comes naturally out of the reconnection process. And we see it in our simulations, too. "
The PSP won't be able to get any closer to the sun than about 8.8 solar radii above the surface — about 4 million miles — without frying its instruments. Bale expects to solidify the team's conclusions with data from that altitude, though the sun is now entering solar maximum, when activity becomes much more chaotic and may obscure the processes the scientists are trying to view.
"There was some consternation at the beginning of the solar probe mission that we're going to launch this thing right into the quietest, most dull part of the solar cycle," Bale said. "But I think without that, we would never have understood this. It would have been just too messy. I think we're lucky that we launched it in the solar minimum."
JOURNAL
Nature
METHOD OF RESEARCH
Experimental study
SUBJECT OF RESEARCH
Not applicable
ARTICLE TITLE
Interchange reconnection as the source of the fast solar wind within coronal holes
ARTICLE PUBLICATION DATE
7-Jun-2023
New study identifies mechanism driving the sun’s fast wind
UMD physicist James Drake says the release of magnetic energy near the sun’s surface enables the solar wind to reach gravity-defying speeds.
Peer-Reviewed PublicationThe fastest winds ever recorded on Earth reached more than 200 miles per hour, but even those gusts pale in comparison to the sun’s wind.
In a paper published June 7, 2023 in the journal Nature, a team of researchers used data from NASA’s Parker Solar Probe to explain how the solar wind is capable of surpassing speeds of 1 million miles per hour. They discovered that the energy released from the magnetic field near the sun’s surface is powerful enough to drive the fast solar wind, which is made up of ionized particles—called plasma—that flow outward from the sun.
James Drake, a Distinguished University Professor in the University of Maryland’s Department of Physics and Institute for Physical Science and Technology (IPST), co-led this research alongside first author Stuart Bale of UC Berkeley. Drake said scientists have been trying to understand solar wind drivers since the 1950s—and with the world more interconnected than ever, the implications for Earth are significant.
The solar wind forms a giant magnetic bubble, known as the heliosphere, that protects planets in our solar system from a barrage of high-energy cosmic rays that whip around the galaxy. However, the solar wind also carries plasma and part of the sun’s magnetic field, which can crash into Earth’s magnetosphere and cause disturbances, including geomagnetic storms.
These storms occur when the sun experiences more turbulent activity, including solar flares and enormous expulsions of plasma into space, known as coronal mass ejections. Geomagnetic storms are responsible for spectacular aurora light shows that can be seen near the Earth’s poles, but at their most powerful, they can knock out a city’s power grid and potentially even disrupt global communications. Such events, while rare, can also be deadly to astronauts in space.
“Winds carry lots of information from the sun to Earth, so understanding the mechanism behind the sun’s wind is important for practical reasons on Earth,” Drake said. “That’s going to affect our ability to understand how the sun releases energy and drives geomagnetic storms, which are a threat to our communication networks.”
Previous studies revealed that the sun’s magnetic field was somehow driving the solar wind, but researchers didn’t know the underlying mechanism. Earlier this year, Drake co-authored a paper which argued that the heating and acceleration of the solar wind is driven by magnetic reconnection—a process that Drake has dedicated his scientific career to studying.
The authors explained that the entire surface of the sun is covered in small “jetlets” of hot plasma that are propelled upward by magnetic reconnection, which occurs when magnetic fields pointing in opposite directions cross-connect. In turn, this triggers the release of massive amounts of energy.
“Two things pointing in opposite directions often wind up annihilating each other, and in this case doing so releases magnetic energy,” Drake said. “These explosions that happen on the sun are all driven by that mechanism. It’s the annihilation of a magnetic field.”
To better understand these processes, the authors of the new Nature paper used data from the Parker Solar Probe to analyze the plasma flowing out of the corona—the outermost and hottest layer of the sun. In April 2021, Parker became the first spacecraft to enter the sun’s corona and has been nudging closer to the sun ever since. The data cited in this paper was taken at a distance of 13 solar radii, or roughly 5.6 million miles from the sun.
“When you get very close to the sun, you start seeing stuff that you just can’t see from Earth,” Drake said. “All the satellites that surround Earth are 210 solar radii from the sun, and now we’re down to 13. We’re about as close as we’re going to get.”
Using this new data, the Nature paper authors provided the first characterization of the bursts of magnetic energy that occur in coronal holes, which are openings in the sun’s magnetic field as well as the source of the solar wind.
The researchers demonstrated that magnetic reconnection between open and closed magnetic fields—known as interchange connection—is a continuous process, rather than a series of isolated events as previously thought. This led them to conclude that the rate of magnetic energy release, which drives the outward jet of heated plasma, was powerful enough to overcome gravity and produce the sun’s fast wind.
By understanding these smaller releases of energy that are constantly occurring on the sun, researchers hope to understand—and possibly even predict—the larger and more dangerous eruptions that launch plasma out into space. In addition to the implications for Earth, findings from this study can be applied to other areas of astronomy as well.
“Winds are produced by objects throughout the universe, so understanding what drives the wind from the sun has broad implications,” Drake said. “Winds from stars, for example, play a crucial role in shielding planetary systems from galactic cosmic rays, which can impact habitability.”
This would not only aid our understanding of the universe, but possibly also the search for life on other planets.
###
In addition to Drake, Marc Swisdak, a research scientist in UMD’s Institute for Research in Electronics and Applied Physics, co-authored this study.
Their paper, “Interchange reconnection as the source of the fast solar wind within coronal holes,” was published in Nature on June 7, 2023.
This study was supported by NASA (Contract No. NNN06AA01C). This story does not necessarily reflect the views of this organization.
JOURNAL
Nature
METHOD OF RESEARCH
Observational study
SUBJECT OF RESEARCH
Not applicable
ARTICLE TITLE
Interchange reconnection as the source of the fast solar wind within coronal holes
ARTICLE PUBLICATION DATE
7-Jun-2023
'Hot Jupiters' may not be orbiting alone
IMAGE: SONGHU WANG. view more
CREDIT: JAMES BROSHER, INDIANA UNIVERSITY
BLOOMINGTON, Ind. — Research led by an Indiana University astronomer challenges longstanding beliefs about the isolation of "hot Jupiters" and proposes a new mechanism for understanding the exoplanets’ evolution.
While our Jupiter is far away from the sun, hot Jupiters are gas giant planets that closely orbit stars outside our solar system for an orbital period of less than 10 days. Previous studies suggested they rarely have any nearby companion planets, leading scientists to believe that hot Jupiters formed and evolved through a violent process that expelled other planets from the area as they moved closer to their host stars. The research team’s findings reveal that hot Jupiters do not always orbit alone.
“Our research shows that at least a fraction of hot Jupiters cannot form through a violent process,” said Songhu Wang, assistant professor of astronomy in the College of Arts and Sciences. “This is a significant contribution to advance our understanding of hot Jupiter formation, which can help us learn more about our own solar system.”
Wang presented the results of the research at the June 2023 meeting of the American Astronomical Society in Albuquerque, New Mexico.
Researchers analyzed the full, four-year data set for hot and warm Jupiters from NASA’s Kepler Mission. Warm Jupiters have a longer orbital period that ranges from 10 to 300 days. Researchers used transit timing variations to determine that at least 12% of hot Jupiters and 70% of warm Jupiters have a nearby planetary companion orbiting their host stars.
Wang and his collaborators combined their results with existing observational constraints to propose a new framework for explaining the evolution of hot and warm Jupiters and why some have companion planets. They determined that the makeup of hot and warm Jupiter systems depends on the occurrence of gas giants in the system, which impacts how much the planets interact and migrate.
The findings provide a launching point into future research about exoplanets and our solar system’s planets.
“The ultimate goal for astronomers is to set our solar system into the bigger picture — 'Are we unique?’” Wang said. “This helps us to understand why we don’t have a hot Jupiter in our solar system.”
Additional collaborators are Dong-Hong Wu, lecturer in the Department of Physics at Anhui Normal University, and Malena Rice, 51 Pegasi b Fellow at the Massachusetts Institute of Technology and incoming professor at Yale University.
Wang has long been interested in the configurations and demographics of exoplanets. He uses observational research to try to understand their dynamics and origins, helping astronomers better understand how our solar system fits into a larger cosmic context.
JOURNAL
The Astronomical Journal
METHOD OF RESEARCH
Data/statistical analysis
ARTICLE TITLE
Evidence for Hidden Nearby Companions to Hot Jupiters
Gravitational waves innovation could help unlock cosmic secrets
IMAGE: SUPERMASSIVE BLACK HOLE view more
CREDIT: ISTOCK
New frontiers in the study of the universe – and gravitational waves – have been opened up following a breakthrough by University of the West of Scotland (UWS) researchers.
The groundbreaking development in thin film technology promises to enhance the sensitivity of current and future gravitational wave detectors. Developed by academics at UWS’s Institute of Thin Films, Sensors and Imaging (ITFSI), the innovation could enhance the understanding of the nature of the universe.
Gravitational waves, first predicted by Albert Einstein's theory of general relativity, are ripples in the fabric of spacetime caused by the most energetic events in the cosmos, such as black hole mergers and neutron star collisions. Detecting and studying these waves provides invaluable insights into the fundamental nature of the universe.
Dr Carlos Garcia Nuñez, Senior Lecturer at School of Computing, Engineering and Physical Sciences (CEPS), said: “At the Institute of Thin Films, Sensors and Imaging, we are working hard to push the limits of thin film materials, exploring new techniques to deposit them, controlling their properties in order to match the requirements of current and future sensing technology for the detection of gravitational waves.”
“The development of high reflecting mirrors with low thermal noise opens a wide range of applications, which covers from the detection of gravitational waves from cosmological events to the development of quantum computers.”
The technique used in this work - originally developed and patented by Professor Des Gibson, Director of UWS’s Institute of Thin Films, Sensors and Imaging – could enable the production of thin films that achieve low levels of “thermal noise”. The reduction of this kind of noise in mirror coatings is essential to increase the sensitivity of current gravitational wave detectors - allowing the detection of a wider range of cosmological events - and could be deployed to enhance other high-precision devices, such as atomic clocks or quantum computers.
Professor Gibson said: "We are thrilled to unveil this cutting-edge thin film technology for gravitational wave detection. This breakthrough represents a significant step forward in our ability to explore the universe and unlock its secrets through the study of gravitational waves. We believe this advancement will accelerate scientific progress in this field and open up new avenues for discovery."
“UWS's thin film technology has already undergone extensive testing and validation in collaboration with renowned scientists and research institutions. The results have been met with great enthusiasm, fuelling anticipation for its future impact on the field of gravitational wave astronomy. The coating deposition technology is being commercialised by UWS spinout company, Albasense Ltd.”
The development of coatings with low thermal noise will not only make future generation of gravitational wave detectors more precise and sensitive to cosmic events, but will also provide new solutions to atomic clocks and quantum mechanics, both highly relevant for the United Nations’ Sustainable Development Goals 7, 9 and 11.
JOURNAL
Optica
SUBJECT OF RESEARCH
Not applicable
ARTICLE TITLE
Amorphous dielectric optical coatings deposited by plasma ion-assisted electron beam evaporation for gravitational wave detectors
Not your average space explosion: Very long baseline array finds classical novae are anything but simple
Reports and ProceedingsIMAGE: THIS ARTIST’S CONCEPTION DEPICTS V1674 HERCULIS, A CLASSICAL NOVA HOSTED IN A BINARY STAR SYSTEM THAT IS MADE UP OF A WHITE DWARF AND DWARF COMPANION STAR. SCIENTISTS STUDYING THIS NOVA HAVE DETECTED NON-THERMAL EMISSION, A DEPARTURE FROM THE HISTORICAL BELIEF THAT THESE SYSTEMS PRODUCE ONLY THERMAL EMISSIONS. view more
CREDIT: B. SAXTON (NRAO/AUI/NSF)
While studying classical novae using the National Radio Astronomy Observatory’s Very Long Baseline Array (VLBA), a graduate researcher uncovered evidence the objects may have been erroneously typecast as simple. The new observations, which detected non-thermal emission from a classical nova with a dwarf companion, were presented today at a press conference during the 242nd proceedings of the American Astronomical Society in Albuquerque, New Mexico.
V1674 Herculis is a classical nova hosted by a white dwarf and dwarf companion and is currently the fastest classical nova on record. While studying V1674Her with the VLBA, Montana Williams, a graduate student at New Mexico Tech who is leading the investigation into the VLBA properties of this nova, confirmed the unexpected: non-thermal emission coming from it. This data is important because it tells Williams and her collaborators a lot about what’s happening in the system. What the team has found is anything but the simple heat-induced explosions scientists previously expected from classical novae.
“Classical novae have historically been considered simple explosions, emitting mostly thermal energy,” said Williams. “However, based on recent observations with the Fermi Large Area Telescope, this simple model is not entirely correct. Instead, it seems they’re a bit more complicated. Using the VLBA, we were able to get a very detailed picture of one of the main complications, the non-thermal emission.”
Very long baseline interferometry (VLBI) detections of classical novae with dwarf companions like V1674Her are rare. They’re so rare, in fact, that this same type of detection, with resolved radio synchrotron components, has been reported just one other time to date. That’s partly because of the assumed nature of classical novae.
“VLBI detections of novae are only recently becoming possible because of improvements to VLBI techniques, most notably the sensitivity of the instruments and the increasing bandwidth or the amount of frequencies we can record at a given time,” said Williams. “Additionally, because of the previous theory of classical novae they weren’t thought to be ideal targets for VLBI studies. We now know this isn’t true because of multi-wavelength observations which indicate a more complex scenario.”
That rarity makes the team’s new observations an important step in understanding the hidden lives of classical novae and what ultimately leads to their explosive behavior.
“By studying images from the VLBA and comparing them to other observations from the Very Large Array (VLA), Fermi-LAT, NuSTAR, and NASA-Swift, we can determine what might be the cause of the emission and also make adjustments to the previous simple model,” said Williams. “Right now, we’re trying to determine if the non-thermal energy is coming from clumps of gas running into other clumped gas which produces shocks, or something else.”
Because Fermi-LAT and Nu-Star observations had already indicated that there might be non-thermal emission coming from V1674Her, that made the classical nova an ideal candidate for study because Williams and her collaborators are on a mission to either confirm or deny those types of findings. It was also more interesting, or cute, as Williams puts it, because of its hyper-fast evolution, and because, unlike supernovae, the host system isn’t destroyed during that evolution, but rather, remains almost completely intact and unchanged after the explosion. “Many astronomical sources don’t change much over the course of a year or even 100 years. But this nova got 10,000 times brighter in a single day, then faded back to its normal state in just about 100 days,” she said. “Because the host systems of classical novae remain intact they can be recurrent, which means we might see this one erupt, or cutely explode, again and again, giving us more opportunities to understand why and how it does.”
The National Radio Astronomy Observatory (NRAO) is a major facility of the National Science Foundation (NSF) operated under cooperative agreement by Associated Universities, Inc.
Scientists studying the classical nova V1674Her have confirmed the presence of non-thermal emissions. The nova, which was discovered in 2021, is the fastest classical nova on record. This image shows the difference in brightness over just four days.
CREDIT
M. Williams/New Mexico Tech, B. Saxton (NRAO/AUI/NSF)
V1674Her is a classical nova located in the constellation Hercules.
CREDIT
IAU/Sky & Telescope
Researchers discover chemical evidence for pair-instability supernova from a very massive first star
IMAGE: STELLAR FOSSIL: IMPRINTS OF PAIR INSTABILITY SUPERNOVAE FROM VERY MASSIVE FIRST STARS. view more
CREDIT: NAOC
The first stars illuminated the Universe during the Cosmic Dawn and put an end to the cosmic "dark ages" that followed the Big Bang. However, the distribution of their mass is one of the great unsolved mysteries of the cosmos.
Numerical simulations of the formation of the first stars estimate that the mass of the first stars reached up to several hundred solar masses. Among them, the first stars with masses between 140 and 260 solar masses ended up as pair-instability supernovae (PISNe). PISNe are quite different from ordinary supernovae (i.e., Type II and Type Ia supernovae) and would have imprinted a unique chemical signature in the atmosphere of the next-generation stars. However, no such signature has been found.
A new study led by Prof. ZHAO Gang from the National Astronomical Observatories of the Chinese Academy of Sciences (NAOC) has identified a chemically peculiar star (LAMOST J1010+2358) in the Galactic halo as clear evidence of the existence of PISNe from very massive first stars in the early Universe, based on the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) survey and follow-up high-resolution spectra observation by Subaru Telescope. It has been confirmed that this star was formed in the gas cloud dominated by the yields of a PISN with 260 solar masses.
The team also includes the researchers from Yunnan Observatories of CAS, National Astronomical Observatory of Japan and Monash University, Australia.
This study was published online in Nature on June 7th.
The research team has performed follow-up high-resolution spectroscopic observation for J1010+2358 with the Subaru telescope and derived abundances for more than ten elements. The most significant feature of this star is its extremely low sodium and cobalt abundances. Its sodium-to-iron ratio is lower than 1/100 of the solar value. This star also exhibits a very large abundance variance between the odd and even charge number elements, such as sodium/magnesium and cobalt/nickel.
"The peculiar odd-even variance, along with deficiencies of sodium and α-elements in this star, are consistent with the prediction of primordial PISN from first-generation stars with 260 solar masses," said Dr. XING Qianfan, first author of the study.
The discovery of J1010+2358 is direct evidence of the hydrodynamical instability due to electron–positron pair production in the theory of very massive star evolution. The creation of electron–positron pairs reduces thermal pressure inside the core of a very massive star and leads to a partial collapse.
"It provides an essential clue to constraining the initial mass function in the early universe," said Prof. ZHAO Gang, corresponding author of the study. "Before this study, no evidence of supernovae from such massive stars has been found in the metal-poor stars."
Moreover, the iron abundance of LAMOST J1010+2358 ([Fe/H] = -2.42) is much higher than the most metal-poor stars in the Galactic halo, suggesting that the second-generation stars formed in the PISN-dominated gas may be more metal-rich than expected.
"One of the holy grails of searching for metal-poor stars is to find evidence for these early pair-instability supernovae," said Prof. Avi Loeb, former chair of the Astronomy Department at Harvard University.
Prof. Timothy Beers, the provost's chair of astrophysics at Notre Dame University, commented on the results: "This paper presents what is, to my knowledge, the first definitive association of a Galactic halo star with an abundance pattern originating from a PISN."
JOURNAL
Nature
ARTICLE TITLE
A metal-poor star with abundances from a pair instability supernova
ARTICLE PUBLICATION DATE
7-Jun-2023
Webb telescope detects universe’s most distant organic molecules
Texas A&M astronomer Justin Spilker and collaborators have found complex organic molecules in a galaxy more than 12 billion light-years away from Earth.
Peer-Reviewed PublicationIMAGE: ASTRONOMERS USING THE WEBB TELESCOPE DISCOVERED EVIDENCE OF COMPLEX ORGANIC MOLECULES SIMILAR TO SMOKE OR SMOG IN THE DISTANT GALAXY SHOWN HERE. THE GALAXY, MORE THAN 12 BILLION LIGHT YEARS AWAY, HAPPENS TO LINE UP ALMOST PERFECTLY WITH A SECOND GALAXY ONLY THREE BILLION LIGHT YEARS AWAY FROM OUR PERSPECTIVE ON EARTH. IN THIS FALSE-COLOR WEBB IMAGE, THE FOREGROUND GALAXY IS SHOWN IN BLUE, WHILE THE BACKGROUND GALAXY IS IN RED. THE ORGANIC MOLECULES ARE HIGHLIGHTED IN ORANGE. view more
CREDIT: J. SPILKER / S. DOYLE, NASA, ESA, CSA
An international team of astronomers has detected complex organic molecules in the most distant galaxy to date using NASA’s James Webb Space Telescope.
The discovery of the molecules, which are familiar on Earth in smoke, soot and smog, demonstrates the power of Webb to help understand the complex chemistry that goes hand-in-hand with the birth of new stars even in the earliest periods of the universe’s history. At least for galaxies, the new findings cast doubt on the old adage that where there’s smoke, there’s fire.
Using the Webb telescope, Texas A&M University astronomer Justin Spilker and collaborators found the organic molecules in a galaxy more than 12 billion light-years away. Because of its extreme distance, the light detected by the astronomers began its journey when the universe was less than 1.5 billion years old — about 10% of its current age. The galaxy was first discovered by the National Science Foundation’s South Pole Telescope in 2013 and has since been studied by many observatories, including the radio telescope ALMA and the Hubble Space Telescope.
Spilker notes the discovery, reported this week in the journal Nature, was made possible through the combined powers of Webb and fate, with a little help from a phenomenon called gravitational lensing. Lensing, originally predicted by Albert Einstein’s theory of relativity, happens when two galaxies are almost perfectly aligned from our point of view on Earth. The light from the background galaxy is stretched and magnified by the foreground galaxy into a ring-like shape, known as an Einstein ring.
“By combining Webb’s amazing capabilities with a natural ‘cosmic magnifying glass,’ we were able to see even more detail than we otherwise could,” said Spilker, an assistant professor in the Texas A&M Department of Physics and Astronomy and a member of the George P. and Cynthia Woods Mitchell Institute for Fundamental Physics and Astronomy. “That level of magnification is actually what made us interested in looking at this galaxy with Webb in the first place, because it really lets us see all the rich details of what makes up a galaxy in the early universe that we could never do otherwise.”
The data from Webb found the telltale signature of large organic molecules akin to smog and smoke —building blocks of the same cancer-causing hydrocarbon emissions on Earth that are key contributors to atmospheric pollution. However, Spilker says the implications of galactic smoke signals are much less disastrous for their cosmic ecosystems.
“These big molecules are actually pretty common in space,” Spilker explained. “Astronomers used to think they were a good sign that new stars were forming. Anywhere you saw these molecules, baby stars were also right there blazing away.”
The new results from Webb show that this idea might not exactly ring true in the early universe, according to Spilker.
“Thanks to the high-definition images from Webb, we found a lot of regions with smoke but no star formation, and others with new stars forming but no smoke,” Spilker added.
University of Illinois Urbana-Champaign graduate student Kedar Phadke, who led the technical development of the team’s Webb observations, noted that astronomers are using Webb to make connections across the vastness of space with unprecedented potential.
“Discoveries like this are precisely what Webb was built to do: understand the earliest stages of the universe in new and exciting ways,” Phadke said. “It’s amazing that we can identify molecules billions of light-years away that we’re familiar with here on Earth, even if they show up in ways we don’t like, like smog and smoke. It’s also a powerful statement about the amazing capabilities of Webb that we’ve never had before.”
The team’s leadership also includes NASA’s Goddard Space Flight Center astronomer Jane Rigby, University of Illinois professor Joaquin Vieira and dozens of astronomers around the world.
The discovery is Webb’s first detection of complex molecules in the early universe — a milestone moment that Spilker sees as a beginning rather than an end.
“These are early days for the Webb Telescope, so astronomers are excited to see all the new things it can do for us,” Spilker said. “Detecting smoke in a galaxy early in the history of the universe? Webb makes this look easy. Now that we’ve shown this is possible for the first time, we’re looking forward to trying to understand whether it’s really true that where there’s smoke, there’s fire. Maybe we’ll even be able to find galaxies that are so young that complex molecules like these haven’t had time to form in the vacuum of space yet, so galaxies are all fire and no smoke. The only way to know for sure is to look at more galaxies, hopefully even further away than this one.”
The team’s paper, “Spatial variations in aromatic hydrocarbon emission in a dust-rich galaxy,” can be viewed online along with related figures and acknowledgements.
JWST is operated by the Space Telescope Science Institute under the management of the Association of Universities for Research in Astronomy under NASA contract NAS 5-03127. The South Pole Telescope is supported by the National Science Foundation, the Department of Energy and the United States Antarctic Program.
CAPTION
The galaxy observed by Webb shows an Einstein ring caused by a phenomenon known as lensing, which occurs when two galaxies are almost perfectly aligned from our perspective on Earth. The gravity from the galaxy in the foreground causes the light from the background galaxy to be distorted and magnified, like looking through the stem of a wine glass. Because they are magnified, lensing allows astronomers to study very distant galaxies in more detail than otherwise possible.
CREDIT
S. Doyle / J. Spilker
JOURNAL
Nature
ARTICLE TITLE
Spatial variations in aromatic hydrocarbon emission in a dust-rich galaxy
ARTICLE PUBLICATION DATE
5-Jun-2023
First detection of secondary supermassive black hole in a well-known binary system
IMAGE: ARTISTIC ILLUSTRATION OF OJ287 AS A BINARY BLACK HOLE SYSTEM. THE SECONDARY BLACK HOLE OF 150 MILLION SOLAR MASSES MOVES AROUND THE PRIMARY BLACK HOLE OF 18 BILLION SOLAR MASSES. A DISK OF GAS SURROUNDS THE LATTER. THE SECONDARY BLACK HOLE IS FORCED TO IMPACT ON THE ACCRETION DISK TWICE DURING ITS 12-YEAR ORBIT. THE IMPACT PRODUCES A BLUE FLASH WHICH WAS DETECTED IN FEBRUARY 2022. IN ADDITION, THE IMPACT ALSO INDUCES THE SECONDARY BLACK HOLE TO BRIGHT BURSTS OF RADIATION SEVERAL WEEKS EARLIER, AND THESE BURSTS HAVE ALSO BEEN DETECTED AS A DIRECT SIGNAL FROM THE SECONDARY BLACK HOLE. view more
CREDIT: AAS 2018
Supermassive black holes that weigh several billion times the mass of our Sun are present at the centres of active galaxies. Astronomers observe them as bright galactic cores where the galaxy’s supermassive black hole devours matter from a violent whirlpool called accretion disk. Some of the matter is squeezed out into a powerful jet. This process makes the galactic core shine brightly across the entire electromagnetic spectrum.
In a recent study, astronomers found evidence of two supermassive black holes circling each other through signals coming from the jets associated with the accretion of matter into both black holes. The galaxy, or a quasar as it is technically called, is named OJ287 and it is most thoroughly studied and best understood as a binary black hole system. In the sky, the black holes are so close together that they merge into one dot. The fact that the dot actually consists of two black holes becomes apparent by detecting that it emits two different types of signals.
The active galaxy OJ 287 lies in the direction of the constellation Cancer at a distance of about 5 billion light years and has been observed by astronomers since 1888. Already more than 40 years ago, astronomer from University of Turku Aimo Sillanpää and his associates noticed that there is a prominent pattern in its emission which has two cycles, one of about 12 years and the longer of about 55 years. They suggested that the two cycles result from the orbital motion of two black holes around each other. The shorter cycle is the orbital cycle and the longer one results from a slow evolution of the orientation of the orbit.
The orbital motion is revealed by a series of flares which arise when the secondary black hole plunges regularly through the accretion disk of the primary black hole at speeds that are a fraction slower than the speed of light. This plunging of the secondary black hole heats the disk material and the hot gas is released as expanding bubbles. These hot bubbles take months to cool while they radiate and cause a flash of light – a flare – that lasts roughly a fortnight and is brighter than a trillion stars.
After decades of efforts at estimating the timing of the secondary black hole’s plunge through the accretion disk, astronomers from the University of Turku in Finland led by Mauri Valtonen and his collaborator Achamveedu Gopakumar from the Tata Institute of Fundamental Research at Mumbai, India, and others were able to model the orbit and to predict accurately when these flares would occur.
Successful observational campaigns in 1983, 1994, 1995, 2005, 2007, 2015 and 2019 allowed the team to observe the predicted flares and to confirm the presence of a supermassive black hole pair in OJ 287.
“The total number of predicted flares now number 26, and nearly all of them have been observed. The bigger black hole in this pair weighs more than 18 billion times the mass of our Sun while the companion is roughly 100 times lighter and their orbit is oblong, not circular,” Professor Achamveedu Gopakumar says.
In spite of these efforts, astronomers had not been able to observe a direct signal from the smaller black hole. Before 2021, its existence had been deduced only indirectly from the flares and from the way it makes the jet of the bigger black hole wobble.
“The two black holes are so close to each other in the sky that one cannot see them separately, they merge to a single point in our telescopes. Only if we see clearly separate signals from each black hole can we say that we have actually “seen” them both,” says the lead author, Professor Mauri Valtonen.
Smaller black hole directly observed for the first time
Excitingly, the observational campaigns in 2021/2022 on OJ 287 using a large number of telescopes of various types allowed researchers to obtain observations of the secondary black hole plunging through the accretion disk for the first time, and the signals arising from the smaller black hole itself.
“The period in 2021/2022 had a special significance in the study of OJ287. Earlier, it had been predicted that during this period the secondary black hole will plunge through the accretion disk of its more massive companion. This plunging was expected to produce a very blue flash right after the impact, and it was indeed observed, within days of the predicted time, by Martin Jelinek and associates at the Czech Technical University and Astronomical Institute of Czechia,” says Professor Mauri Valtonen.
However, there were two big surprises – new types of flares which had not been detected before. The first of them was seen only by a detailed observation campaign by Staszek Zola from the Jagiellonian University of Cracow, Poland, and for a good reason. Zola and his team observed a big flare, producing 100 times more light than an entire galaxy, and it lasted only one day.
“According to the estimates, the flare occurred shortly after the smaller black hole had received a massive dose of new gas to swallow during its plunge. It is the swallowing process that leads to the sudden brightening of OJ287. It is thought that this process has empowered the jet which shoots out from the smaller black hole of OJ 287. An event like this was predicted ten years ago, but has not been confirmed until now,” Valtonen explains.
The second unexpected signal came from gamma rays and it was observed by NASA’s Fermi telescope. The biggest gamma ray flare in OJ287 for six years happened just when the smaller black hole plunged through the gas disk of the primary black hole. The jet of the smaller black hole interacts with the disk gas, and this interaction leads to the production of gamma rays. To confirm this idea, the researchers verified that a similar gamma ray flare had already taken place in 2013 when the small black hole fell through the gas disk last time, seen from the same viewing direction.
“So what about the one-day burst, why have we not seen it before? OJ287 has been recorded in photographs since 1888 and has been intensively followed since 1970. It turns out that we have simply just had bad luck. Nobody observed OJ287 exactly on those nights when it did its one-night stunt. And without the intense monitoring by Zola’s group, we would have missed it this time as well,” Valtonen states.
These efforts make OJ 287 the best candidate for a supermassive black hole pair that is sending gravitational waves in nano-hertz frequencies. Further, OJ 287 is being routinely monitored by both the Event Horizon Telescope (EHT) and the Global mm-VLBI Array (GMVA) consortia to probe for additional evidence for the presence of supermassive black hole pair at its centre and, in particular, to try to get the radio image of the secondary jet.
The instruments that were part of the 2021-2022 campaign include NASA’s Fermi gamma ray telescope and the Swift ultraviolet to x-ray telescope, optical wavelength observations by astronomers in Czech Republic, Finland, Germany, Spain, Italy, Japan, India, China, Great Britain and USA, and radio frequency observations of OJ287 at Aalto University, Helsinki, Finland.
JOURNAL
Monthly Notices of the Royal Astronomical Society
ARTICLE TITLE
Refining the OJ 287 2022 impact flare arrival epoch
