SPACE NEWS
Two studies of volatile elements discovered in meteorites constrain the assembly of Earth
In two separate studies, researchers identify nucleosynthetic isotope anomalies in the volatile elements potassium (K) and zinc (Zn) in meteorites, which constrain the origins of the material that formed Earth. According to both studies, roughly 90% of Earth’s mass was contributed by non-carbonaceous (NC) material from the inner Solar System and about 10% by carbonaceous chondrite (CC) material from the outer Solar System. The CC reservoir provided Earth with about 20% of its K and half of its Zn. Together, the studies indicate that volatile elements were not evenly distributed in the hot solar nebula that formed the Solar System.
Nucleosynthetic anomalies are small differences in the isotope ratios of chemical elements, produced when those elements formed. During the formation of the Solar System, elements carrying these nucleosynthetic anomalies condensed from the gas phase to form solid dust, which was then incorporated into meteorites and the terrestrial planets, including Earth. Different nucleosynthetic anomalies were inherited by material in different parts of the early Solar System. The origin of the material that formed Earth can be constrained by measuring the nucleosynthetic anomalies of meteorites. However, the nucleosynthetic anomalies of volatile elements - those that condense at low temperature - have been difficult to measure, so their origin was poorly constrained.
Nicole Nie, Da Wang, and colleagues measured three K isotopes (39K, 40K and 41K) in 32 meteorites. The researchers found nucleosynthetic anomalies in the isotope 40K, which were larger and more variable in CC meteorites than in NC meteorites. According to the findings, the 40K nucleosynthesis anomaly ratio of Earth rocks closely matches that of NCs, suggesting that most of Earth’s K was delivered by NCs and less than 20% by CCs.
In another study, Rayssa Martins, Sven Kuthning, and colleagues focused on another volatile element, Zn. The authors analyzed the five stable isotopes of Zn in 18 meteorites. They identified nucleosynthetic anomalies in zinc isotopes that differ between the CC and NC meteorites. When compared to the isotopic signature of Earth’s Zn, Martins, Kuthning, et al.’s findings suggest a mixed source of the element. The authors calculate that about 10% of Earth’s total mass was derived from CC meteorites, including 50% of its Zn. The findings indicate that CC material from the outer Solar System could have substantially to contributed Earth’s other volatile elements.
“Our studies complement and confirm each other’s results in multiple ways,” writes Nie in an accompanying questionnaire by both research groups, discussing the findings of both studies and their implications. “Among moderately volatile elements, K is the least volatile while Zn is one of the most volatile elements, our studies thus predict that a wide range of volatile elements should have preserved nucleosynthetic anomalies.”
JOURNAL
Science
ARTICLE TITLE
Meteorites have inherited nucleosynthetic anomalies of potassium-40 produced in supernovae
ARTICLE PUBLICATION DATE
27-Jan-2023
Meteorites reveal likely origin of Earth’s
volatile chemicals
Imperial College London press release
FOR IMMEDIATE RELEASE
By analysing meteorites, Imperial researchers have uncovered the likely far-flung origin of Earth’s volatile chemicals, some of which form the building blocks of life.
They found that around half the Earth’s inventory of the volatile element zinc came from asteroids originating in the outer Solar System – the part beyond the asteroid belt that includes the planets Jupiter, Saturn, and Uranus. This material is also expected to have supplied other important volatiles such as water.
Volatiles are elements or compounds that change from solid or liquid state into vapour at relatively low temperatures. They include the six most common elements found in living organisms, as well as water. As such, the addition of this material will have been important for the emergence of life on Earth.
Prior to this, researchers thought that most of Earth’s volatiles came from asteroids that formed closer to the Earth. The findings reveal important clues about how Earth came to harbour the special conditions needed to sustain life.
Senior author Professor Mark Rehkämper, of Imperial College London’s Department of Earth Science and Engineering, said: “Our data show that about half of Earth’s zinc inventory was delivered by material from the outer Solar System, beyond the orbit of Jupiter. Based on current models of early Solar System development, this was completely unexpected.”
Previous research suggested that the Earth formed almost exclusively from inner Solar System material, which researchers inferred was the predominant source of Earth’s volatile chemicals. In contrast, the new findings suggest the outer Solar System played a bigger role than previously thought.
Professor Rehkämper added: “This contribution of outer Solar System material played a vital role in establishing the Earth’s inventory of volatile chemicals. It looks as though without the contribution of outer Solar System material, the Earth would have a much lower amount of volatiles than we know it today – making it drier and potentially unable to nourish and sustain life.”
The findings are published today in Science.
To carry out the study, the researchers examined 18 meteorites of varying origins – eleven from the inner Solar System, known as non-carbonaceous meteorites, and seven from the outer Solar System, known as carbonaceous meteorites.
For each meteorite they measured the relative abundances of the five different forms – or isotopes – of zinc. They then compared each isotopic fingerprint with Earth samples to estimate how much each of these materials contributed to the Earth’s zinc inventory. The results suggest that while the Earth only incorporated about ten per cent of its mass from carbonaceous bodies, this material supplied about half of Earth’s zinc.
The researchers say that material with a high concentration of zinc and other volatile constituents is also likely to be relatively abundant in water, giving clues about the origin of Earth’s water.
First author on the paper Rayssa Martins, PhD candidate at the Department of Earth Science and Engineering, said: “We’ve long known that some carbonaceous material was added to the Earth, but our findings suggest that this material played a key role in establishing our budget of volatile elements, some of which are essential for life to flourish.”
Next the researchers will analyse rocks from Mars, which harboured water 4.1 to 3 billion years ago before drying up, and the Moon. Professor Rehkämper said: “The widely held theory is that the Moon formed when a huge asteroid smashed into an embryonic Earth about 4.5 billion years ago. Analysing zinc isotopes in moon rocks will help us to test this hypothesis and determine whether the colliding asteroid played an important part in delivering volatiles, including water, to the Earth.”
This work was funded by the Science and Technology Facilities Council (STFC – part of UKRI) and Rayssa Martins is funded by an Imperial College London Presidents’ PhD Scholarship.
For more information contact:
Caroline Brogan
caroline.brogan@imperial.ac.uk
+44(0)20 7594 3415
Out of hours: +44 (0)7803 886248
NOTES TO EDITORS:
For embargoed paper see: https://imperialcollegelondon.box.com/s/0c5blfym8n8e9jp44oeig7wqkxxkzmgd
“Nucleosynthetic isotope anomalies of zinc in meteorites constrain the origin of Earth’s volatiles” by Martins et al., published 26 January 2023 in Science.
About Imperial College London
Imperial College London is a global top ten university with a world-class reputation. The College's 22,000 students and 8,000 staff are working to solve the biggest challenges in science, medicine, engineering and business.
The Research Excellence Framework (REF) 2021 found that it has a greater proportion of world-leading research than any other UK university, it was named University of the Year 2022 according to The Times and Sunday Times Good University Guide, University of the Year for Student Experience 2022 by the Good University Guide, and awarded a Queen’s Anniversary Prize for its COVID-19 response.
JOURNAL
Science
ARTICLE TITLE
Nucleosynthetic isotope anomalies of zinc in meteorites constrain the origin of Earth’s volatiles
ARTICLE PUBLICATION DATE
26-Jan-2023
Solar System formed from “poorly mixed cake batter,” isotope research shows
New work reveals Earth’s potassium arrived by meteoritic delivery service
Peer-Reviewed PublicationIMAGE: A METEORITE THIN SECTION UNDER A MICROSCOPE. DIFFERENT COLORS REPRESENT DIFFERENT MINERALS, BECAUSE LIGHT TRAVELS THROUGH THEM IN DIFFERENT WAYS. THE ROUND MINERAL AGGREGATES ARE CHONDRULES, WHICH ARE A MAJOR COMPONENT IN PRIMITIVE METEORITES. view more
CREDIT: CREDIT: NICOLE XIKE NIE.
Washington, DC—Earth’s potassium arrived by meteoritic delivery service finds new research led by Carnegie’s Nicole Nie and Da Wang. Their work, published in Science, shows that some primitive meteorites contain a different mix of potassium isotopes than those found in other, more-chemically processed meteorites. These results can help elucidate the processes that shaped our Solar System and determined the composition of its planets.
“The extreme conditions found in stellar interiors enable stars to manufacture elements using nuclear fusion,” explained Nie, a former Carnegie postdoc now at Caltech. “Each stellar generation seeds the raw material from which subsequent generations are born and we can trace the history of this material across time.”
Some of the material produced in the interiors of stars can be ejected out into space, where it accumulates as a cloud of gas and dust. More than 4.5 billion years ago, one such cloud collapsed in on itself to form our Sun.
The remnants of this process formed a rotating disk around the newborn star. Eventually, the planets and other Solar System objects coalesced from these leftovers, including the parent bodies that later broke apart to become asteroids and meteorites.
“By studying variations in the isotopic record preserved within meteorites, we can trace the source materials from which they formed and build a geochemical timeline of our Solar System’s evolution,” added Wang, who is now at Chengdu University of Technology.
Each element contains a unique number of protons, but its isotopes have varying numbers of neutrons. The distribution of different isotopes of the same element throughout the Solar System is a reflection of the makeup of the cloud of material from which the Sun was born. Many stars contributed to this so-called solar molecular cloud, but their contributions were not uniform, which can be determined by studying the isotopic content of meteorites.
Wang and Nie—along with Carnegie colleagues Anat Shahar, Zachary Torrano, Richard Carlson, and Conel Alexander—measured the ratios of three potassium isotopes in samples from 32 different meteorites.
Potassium is particularly interesting because it’s what’s called a moderately volatile element, which are named for having relatively low boiling points that cause them to evaporate fairly easily. As a result, it’s challenging to look for patterns that predate the Sun in the isotopic ratios of volatiles—they just don’t stick around in the hot star-forming conditions long enough to maintain an easily readable record.
“However, using very sensitive and suitable instruments, we found patterns in the distribution of our potassium isotopes that were inherited from pre-solar materials and differed between types of meteorites,” Nie said.
They found that some of the most primitive meteorites called carbonaceous chondrites, which formed in the outer Solar System, contained more potassium isotopes that were produced by huge stellar explosions, called supernovae. Whereas other meteorites—those that most frequently crash to Earth, called non-carbonaceous chondrites—contain the same potassium isotope ratios seen on our home planet and elsewhere in the inner Solar System.
“This tells us that, like a poorly mixed cake batter, there wasn’t an even distribution of materials between the outer reaches of the Solar System where the carbonaceous chondrites formed, and the inner Solar System, where we live,” concluded Shahar.
For years, Carnegie Earth and planetary scientists have worked to reveal the origins of Earth’s volatile elements. Some of these elements may have been transported here all the way from the outer Solar System on the backs of carbonaceous chondrites. However, since the pattern of pre-solar potassium isotopes found in non-carbonaceous chondrites matched that seen on Earth, these meteorites are the probable source of our planet’s potassium.
“It is only recently that scientists challenged a once long-held belief that the conditions in the solar nebula that birthed our Sun were hot enough to burn off all volatile elements,” Shahar added. “This research provides fresh evidence that volatiles could survive the Sun’s formation.”
More research is needed to apply this new knowledge to our models of planet formation and see if it adjusts any long-held beliefs about how Earth and its neighbors came into being.
__________________
This work was supported by a NASA NESSF fellowship, Carnegie postdoctoral fellowships, and a Carnegie Postdoc × Postdoc (P2) seed grant.
The Carnegie Institution for Science (carnegiescience.edu) is a private, nonprofit organization headquartered in Washington, D.C., with three research divisions on both coasts. Since its founding in 1902, the Carnegie Institution has been a pioneering force in basic scientific research. Carnegie scientists are leaders in the life and environmental sciences, Earth and planetary science, and astronomy and astrophysics.
JOURNAL
Science
METHOD OF RESEARCH
Experimental study
SUBJECT OF RESEARCH
Not applicable
ARTICLE TITLE
Meteorites have inherited nucleosynthetic anomalies of potassium-40 produced in supernovae
ARTICLE PUBLICATION DATE
27-Jan-2023
A meteorite thin section under a microscope, featuring a chondrule with complex textures. Chondrules are among the oldest materials in the Solar System.
Credit: Nicole Xike Nie.
Starry tail tells the tale of dwarf galaxy evolution
IMAGE: (LEFT) M81 GROUP SURVEY FOOTPRINT (WHITE AND RED CIRCLES) OVERLAID ON A SLOAN DIGITAL SKY SURVEY IMAGE. (RIGHT) THE SPATIAL DISTRIBUTION OF RED GIANT BRANCH STARS AT THE SAME DISTANCE AS F8D1 IN THE FIELD DELINEATED BY THE RED CIRCLE IN THE LEFT PANEL. THE UPPER RIGHT IMAGE IS A ZOOM IN ON THE MAIN BODY OF THE F8D1 GALAXY. view more
CREDIT: NAOJ
A giant diffuse tail of stars has been discovered emanating from a large, faint dwarf galaxy. The presence of a tail indicates that the galaxy has experienced recent interaction with another galaxy. This is an important clue for understanding how so called “ultra-diffuse” galaxies are formed.
Astronomers using the Subaru Telescope and the Canada-France-Hawaii Telescope found a tail of stars stretching 200,000 light-years out away from a galaxy known as F8D1. This galaxy is a member of the M81 group located 12 million light-years away on the boundary between the constellations Ursa Major and Camelopardalis. F8D1 is one of the closest examples of an “ultra-diffuse” galaxy. The origin of these enigmatic galaxies has puzzled astronomers for several decades: are they born this diffuse or does some later event cause them to puff up in size?
The discovery of a huge tidal tail from F8D1 is compelling evidence that the galaxy has been strongly shaped by events in the past billion years. This is the first time that such a stellar stream has been discovered in a UDG. The team suggests F8D1 was disrupted by a recent close passage to the massive spiral M81, the dominant member of the group containing F8D1.
Since F8D1 lies at the edge of the survey area, only one tidal arm can be seen, extending to the northeast. The team will now search to see if there is a counterpart stream to the southwest.
These results appeared as Žemaitis et al. “A tale of a tail: a tidally disrupting ultra-diffuse galaxy in the M81 group” in the Monthly Notices of the Royal Astronomical Society on November 2, 2022.
JOURNAL
Monthly Notices of the Royal Astronomical Society
METHOD OF RESEARCH
Observational study
SUBJECT OF RESEARCH
Not applicable
ARTICLE TITLE
A tale of a tail: a tidally disrupting ultra-diffuse galaxy in the M81 group
NASA’s Webb Telescope receives top space foundation award
Business AnnouncementIMAGE: THE PROTOSTAR WITHIN THE DARK CLOUD L1527, SHOWN IN THIS IMAGE FROM NASA’S JAMES WEBB SPACE TELESCOPE NEAR-INFRARED CAMERA (NIRCAM), IS EMBEDDED WITHIN A CLOUD OF MATERIAL FEEDING ITS GROWTH. EJECTIONS FROM THE STAR HAVE CLEARED OUT CAVITIES ABOVE AND BELOW IT, WHOSE BOUNDARIES GLOW ORANGE AND BLUE IN THIS INFRARED VIEW. THE UPPER CENTRAL REGION DISPLAYS BUBBLE-LIKE SHAPES DUE TO STELLAR “BURPS,” OR SPORADIC EJECTIONS. view more
CREDIT: CREDITS: NASA, ESA, CSA, AND STSCI. IMAGE PROCESSING: J. DEPASQUALE, A. PAGAN, AND A. KOEKEMOER (STSCI)
NASA’s James Webb Space Telescope team has been selected to receive the 2023 John L. “Jack” Swigert, Jr., Award for Space Exploration, a top award from the Space Foundation. This annual award honors a space agency, company, or consortium of organizations in the realm of space exploration and discovery.
“The James Webb Space Telescope team represents the best of our humanity and an enduring pursuit to better understand the cosmos. Every new image is a new discovery,” said NASA Administrator Bill Nelson. “Webb is the culmination of decades of persistence and once-unthinkable human ingenuity made possible by international partnerships. Together, we are unfolding the universe and inspiring the world.”
The award will be presented at the Space Foundation’s yearly opening ceremony of the Space Symposium in Colorado on April 17.
“Within its first year of operations, the work and revelations by the James Webb Space Telescope team has opened an entirely new chapter of knowledge and inspiration that will forever change our lives and history,” said Space Foundation CEO Tom Zelibor. “This is an unparalleled achievement and is transforming astronomy and space science while delivering new inspiration and imagination to every generation and corner of our planet. The partnerships and collaborations between nations, researchers, industry members, and more have also highlighted the incredible things we can do together as we promote knowledge.”
Webb, the world’s premier space science telescope, launched Dec. 25, 2021. In 2022, the Webb team successfully completed an intricate series of deployments to unfold the observatory into its final configuration in space. They then precisely aligned its mirrors to within nanometers, set up and tested its powerful instruments, and officially began Webb’s mission to explore the infrared universe.
With its optics performing nearly twice as well as the mission required, Webb is discovering some of the earliest galaxies ever observed, peering through dusty clouds to see stars forming, and delivering a more detailed view of the atmospheres of planets outside our solar system than ever before. Webb has also captured new views of planets within our solar system, including the clearest look at Neptune’s rings in decades. The Swigert award, which pays tribute to NASA astronaut Jack Swigert for his legacy of space exploration, will recognize the contributions of the team members who designed, developed, and now operate the Webb mission.
“Our vast and dedicated team on the James Webb Space Telescope mission is already bringing us closer and closer to seeing the earliest, most distant galaxies that shine in our universe,” said Sandra Connelly, acting associate administrator for the Science Mission Directorate at NASA Headquarters. “Webb is an international collaboration involving a group of thousands of diverse people that has launched NASA into a new era of world-class science and is revolutionizing our view of the cosmos.”
Recent winners of the John L. “Jack” Swigert, Jr. Award include NASA and the University of Arizona OSIRIS-REx team, the teams behind the NASA JPL Mars Ingenuity Helicopter and InSight-Mars Cube One, NASA Dawn, and Cassini.
NASA's James Webb Space Telescope in a cleanroom.
CREDIT NASA
Webb, an international mission led by NASA with its partners ESA (European Space Agency) and CSA (Canadian Space Agency), is the world’s premier space science observatory. Its design pushed the boundaries of space telescope capabilities to solve mysteries in our solar system, look beyond to distant worlds around other stars, and probe the mysterious structures and origins of our universe and our place in it.
NASA Headquarters in Washington oversees the Webb mission. NASA Goddard manages Webb for the agency and oversees work on the mission performed by the Space Telescope Science Institute, Northrop Grumman, and other mission partners, including Ball Aerospace. In addition to Goddard, several NASA centers contributed to the project, including the agency’s Johnson Space Center in Houston, Jet Propulsion Laboratory in southern California, Marshall Space Flight Center in Huntsville, Alabama, Ames Research Center in California’s Silicon Valley, and others.
Recently, the Webb mission’s accomplishments also have been recognized by organizations including the National Space Club and Foundation, National Air and Space Museum, Aviation Week, Bloomberg Businessweek, Popular Science, and TIME.
For more information about the Webb mission, visit:
BepiColombo and Solar Orbiter compare notes at Venus
IMAGE: THE CONVERGENCE OF BEPICOLOMBO AND SOLAR ORBITER SPACECRAFT AT VENUS IN AUGUST 2021 WAS A RARE OPPORTUNITY TO INVESTIGATE THE ‘STAGNATION REGION’, AN AREA OF THE VENUSIAN MAGNETOSPHERE WHERE SOME OF THE LARGEST EFFECTS OF THE INTERACTION BETWEEN VENUS AND THE SOLAR WIND ARE OBSERVED. view more
CREDIT: THIBAUT ROGER/EUROPLANET 2024 RI
The convergence of two spacecraft at Venus in August 2021 has given a unique insight into how the planet is able to retain its thick atmosphere without the protection of a global magnetic field.
The ESA/JAXA BepiColombo mission, enroute to study Mercury, and the ESA/NASA Solar Orbiter, which is observing the Sun from different perspectives, are both using a number of gravity-assists from Venus to change their trajectories and guide them on their way. On 9-10 August 2021, the missions flew past Venus within a day of each other, sending back observations synergistically captured from eight sensors and two vantage points in space. The results have been published in Nature Communications.
Unlike Earth, Venus does not generate an intrinsic magnetic field in its core. Nonetheless, a weak, comet-shaped ‘induced magnetosphere’ is created around the planet by the interaction of the solar wind – a stream of charged particles emitted by the Sun – with electrically charged particles in Venus’s upper atmosphere. Around this magnetic bubble, the solar wind is slowed, heated and deflected like the wake of a boat in a region called ‘magnetosheath’.
During the flyby, BepiColombo swooped along the long tail of the magnetosheath and emerged through the blunt nose of the magnetic regions closest to the Sun. Meanwhile, Solar Orbiter captured a peaceful solar wind from its location upfront of Venus.
“These dual sets of observations are particularly valuable because the solar wind conditions experienced by Solar Orbiter were very stable. This meant that BepiColombo had a perfect view of the different regions within the magnetosheath and magnetosphere, undisturbed by fluctuations from solar activity,” said lead-author Moa Persson of the University of Tokyo in Kashiwa, Japan, who was funded to carry out the study by the European Commission through the Europlanet 2024 Research Infrastructure (RI) project.
BepiColombo’s flyby was a rare opportunity to investigate the ‘stagnation region’, an area at the nose of the magnetosphere where some of the largest effects of the interaction between Venus and the solar wind are observed. The data gathered gave the first experimental evidence that charged particles in this region are slowed significantly by the interactions between the solar wind and Venus, and that the zone extends to an unexpectedly large distance of 1,900 kilometres above the planet’s surface.
The observations also showed that the induced magnetosphere provides a stable barrier that protects the atmosphere of Venus from being eroded by the solar wind. This protection remains robust even during solar minimum, when lower ultraviolet emissions from the Sun reduce the strength of the currents that generate the induced magnetosphere. The finding, which is contrary to previous predictions, sheds new light on the connection between magnetic fields and atmospheric loss due to the solar wind.
‘The effectiveness of an induced magnetosphere in helping a planet retain its atmosphere has implications for understanding the habitability of exoplanets without internally-generated magnetic fields,” said co-author Sae Aizawa of JAXA’s Institute of Space and Astronautical Science (ISAS).
BepiColombo comprises a pair of spacecraft, Mio, the JAXA-led Mercury Magnetospheric Orbiter, and MPO, the ESA-led Mercury Planetary Orbiter, which have been stacked together for the journey to Mercury. The study combined data from Mio’s four particle sensors, the magnetometer and another particle instrument on MPO, and the magnetometer and solar wind analyser on Solar Orbiter. Europlanet’s SPIDER space weather modelling tools enabled the researchers to track in detail how features in the solar wind observed by Solar Orbiter were affected as they propagated towards BepiColombo through the venusian magnetosheath.
“The important results of this study demonstrate how turning sensors on during planetary flybys and cruise phases can lead to unique science,” said co-author Nicolas Andre, the coordinator of the Europlanet SPIDER service at the Institut de Recherche en Astrophysique et Planétologie (IRAP) in Toulouse, France.
JOURNAL
Nature Communications
METHOD OF RESEARCH
Observational study
SUBJECT OF RESEARCH
Not applicable
ARTICLE TITLE
BepiColombo mission confirms stagnation region of Venus and reveals its large extent
Webb spies Chariklo ring system with high-precision technique
IMAGE: AN OCCULTATION LIGHT CURVE FROM WEBB’S NEAR-INFRARED CAMERA (NIRCAM) INSTRUMENT AT 1.5 MICRONS WAVELENGTH (F150W) SHOWS THE DIPS IN BRIGHTNESS OF THE STAR (GAIA DR3 6873519665992128512) AS CHARIKLO’S RINGS PASSED IN FRONT OF IT ON OCT. 18. AS SEEN IN THE ILLUSTRATION OF THE OCCULTATION EVENT, THE STAR DID NOT PASS BEHIND CHARIKLO FROM WEBB’S VIEWPOINT, BUT IT DID PASS BEHIND ITS RINGS. EACH DIP ACTUALLY CORRESPONDS TO THE SHADOWS OF TWO RINGS AROUND CHARIKLO, WHICH ARE ~4 MILES (6-7 KILOMETERS) AND ~2 MILES (2-4 KILOMETERS) WIDE, AND SEPARATED BY A GAP OF 5.5 MILES (9 KILOMETERS). THE TWO INDIVIDUAL RINGS ARE NOT FULLY RESOLVED IN EACH DIP IN THIS LIGHT CURVE. view more
CREDIT: IMAGE CREDIT: NASA, ESA, CSA, LEAH HUSTAK (STSCI). SCIENCE: PABLO SANTOS-SANZ (IAA/CSIC), NICOLÁS MORALES (IAA/CSIC), BRUNO MORGADO (UFRJ, ON/MCTI, LINEA).
In an observational feat of high precision, scientists used a new technique with NASA’s James Webb Space Telescope to capture the shadows of starlight cast by the thin rings of Chariklo. Chariklo is an icy, small body, but the largest of the known Centaur population, located more than 2 billion miles away beyond the orbit of Saturn. Chariklo is only 160 miles (250 kilometers) or ~51 times smaller than Earth in diameter, and its rings orbit at a distance of about 250 miles (400 kilometers) from the center of the body.
We asked members of the science team observing Chariklo to tell us more about this unique system, the occultation technique, and what they learned from their Webb observations.
In 2013, Felipe Braga-Ribas and collaborators, using ground-based telescopes, discovered that Chariklo hosts a system of two thin rings. Such rings had been expected only around large planets such as Jupiter and Neptune. The astronomers had been watching a star as Chariklo passed in front of it, blocking the starlight as they had predicted. Astronomers call this phenomenon an occultation. To their surprise, the star blinked off and on again twice before disappearing behind Chariklo, and double-blinked again after the star reemerged. The blinking was caused by two thin rings – the first rings ever detected around a small solar system object.
Pablo Santos-Sanz, from Instituto de Astrofísica de Andalucía in Granada, Spain, has an approved “Target of Opportunity” program (program 1271) to attempt an occultation observation as part of Webb’s solar system Guaranteed Time Observations (GTO) led by Heidi Hammel from the Association of Universities for Research in Astronomy. By remarkable good luck, we discovered that Chariklo was on track for just such an occultation event in October 2022. This was the first stellar occultation attempted with Webb. A lot of hard work went into identifying and refining the predictions for this unusual event.
On Oct. 18, we used Webb’s Near-Infrared Camera (NIRCam) instrument to closely monitor the star Gaia DR3 6873519665992128512, and watch for the tell-tale dips in brightness indicating an occultation had taken place. The shadows produced by Chariklo’s rings were clearly detected, demonstrating a new way of using Webb to explore solar system objects. The star shadow due to Chariklo itself tracked just out of Webb’s view. This appulse (the technical name for a close pass with no occultation) was exactly as had been predicted after the last Webb course trajectory maneuver.
The Webb occultation light curve, a graph of an object’s brightness over time, revealed that the observations were successful! The rings were captured exactly as predicted. The occultation light curves will yield interesting new science for Chariklo’s rings. Santos-Sanz explained: “As we delve deeper into the data, we will explore whether we cleanly resolve the two rings. From the shapes of rings’ occultation light curves, we also will explore the rings’ thickness, the sizes and colors of the ring particles, and more. We hope gain insight into why this small body even has rings at all, and perhaps detect new fainter rings.”
The rings are probably composed of small particles of water ice mixed with dark material, debris from an icy body that collided with Chariklo in the past. Chariklo is too small and too far away for even Webb to directly image the rings separated from the main body, so occultations are the only tool to characterize the rings by themselves.
Precision Technique
Editor’s Note: This post highlights data from Webb science in progress, which has not yet been through the peer-review process.
In an observational feat of high precision, scientists used a new technique with NASA’s James Webb Space Telescope to capture the shadows of starlight cast by the thin rings of Chariklo. Chariklo is an icy, small body, but the largest of the known Centaur population, located more than 2 billion miles away beyond the orbit of Saturn. Chariklo is only 160 miles (250 kilometers) or ~51 times smaller than Earth in diameter, and its rings orbit at a distance of about 250 miles (400 kilometers) from the center of the body.
We asked members of the science team observing Chariklo to tell us more about this unique system, the occultation technique, and what they learned from their Webb observations.
In 2013, Felipe Braga-Ribas and collaborators, using ground-based telescopes, discovered that Chariklo hosts a system of two thin rings. Such rings had been expected only around large planets such as Jupiter and Neptune. The astronomers had been watching a star as Chariklo passed in front of it, blocking the starlight as they had predicted. Astronomers call this phenomenon an occultation. To their surprise, the star blinked off and on again twice before disappearing behind Chariklo, and double-blinked again after the star reemerged. The blinking was caused by two thin rings – the first rings ever detected around a small solar system object.
Pablo Santos-Sanz, from Instituto de Astrofísica de Andalucía in Granada, Spain, has an approved “Target of Opportunity” program (program 1271) to attempt an occultation observation as part of Webb’s solar system Guaranteed Time Observations (GTO) led by Heidi Hammel from the Association of Universities for Research in Astronomy. By remarkable good luck, we discovered that Chariklo was on track for just such an occultation event in October 2022. This was the first stellar occultation attempted with Webb. A lot of hard work went into identifying and refining the predictions for this unusual event.
On Oct. 18, we used Webb’s Near-Infrared Camera (NIRCam) instrument to closely monitor the star Gaia DR3 6873519665992128512, and watch for the tell-tale dips in brightness indicating an occultation had taken place. The shadows produced by Chariklo’s rings were clearly detected, demonstrating a new way of using Webb to explore solar system objects. The star shadow due to Chariklo itself tracked just out of Webb’s view. This appulse (the technical name for a close pass with no occultation) was exactly as had been predicted after the last Webb course trajectory maneuver.
This video shows observations taken by NASA’s James Webb Space Telescope of a star (fixed in the center of the video) as Chariklo passes in front of it. The video is composed of 63 individual observations with Webb’s Near-infrared Camera Instrument’s view at 1.5 microns wavelength (F150W) obtained over ~1 hour on Oct. 18. Careful analysis of the star’s brightness reveals that the rings of the Chariklo system were clearly detected. Credit: NASA, ESA, CSA, Nicolás Morales (IAA/CSIC)
The Webb occultation light curve, a graph of an object’s brightness over time, revealed that the observations were successful! The rings were captured exactly as predicted. The occultation light curves will yield interesting new science for Chariklo’s rings. Santos-Sanz explained: “As we delve deeper into the data, we will explore whether we cleanly resolve the two rings. From the shapes of rings’ occultation light curves, we also will explore the rings’ thickness, the sizes and colors of the ring particles, and more. We hope gain insight into why this small body even has rings at all, and perhaps detect new fainter rings.”
The rings are probably composed of small particles of water ice mixed with dark material, debris from an icy body that collided with Chariklo in the past. Chariklo is too small and too far away for even Webb to directly image the rings separated from the main body, so occultations are the only tool to characterize the rings by themselves.
An occultation light curve from Webb’s Near-infrared Camera (NIRCam) Instrument at 1.5 microns wavelength (F150W) shows the dips in brightness of the star (Gaia DR3 6873519665992128512) as Chariklo’s rings passed in front of it on Oct. 18. As seen in the illustration of the occultation event, the star did not pass behind Chariklo from Webb’s viewpoint, but it did pass behind its rings. Each dip actually corresponds to the shadows of two rings around Chariklo, which are ~4 miles (6-7 kilometers) and ~2 miles (2-4 kilometers) wide, and separated by a gap of 5.5 miles (9 kilometers). The two individual rings are not fully resolved in each dip in this light curve. Image credit: NASA, ESA, CSA, Leah Hustak (STScI). Science: Pablo Santos-Sanz (IAA/CSIC), Nicolás Morales (IAA/CSIC), Bruno Morgado (UFRJ, ON/MCTI, LIneA). Download the full-resolution version from the Space Telescope Science Institute.
Shortly after the occultation, Webb targeted Chariklo again, this time to collect observations of the sunlight reflected by Chariklo and its rings (GTO Program 1272). The spectrum of the system shows three absorption bands of water ice in the Chariklo system. Noemí Pinilla-Alonso, who led Webb’s spectroscopic observations of Chariklo, explained: “Spectra from ground-based telescopes had hinted at this ice (Duffard et al. 2014), but the exquisite quality of the Webb spectrum revealed the clear signature of crystalline ice for the first time.” Dean Hines, the principal investigator of this second GTO program, added: “Because high-energy particles transform ice from crystalline into amorphous states, detection of crystalline ice indicates that the Chariklo system experiences continuous micro-collisions that either expose pristine material or trigger crystallization processes.”
Most of the reflected light in the spectrum is from Chariklo itself: Models suggest the observed ring area as seen from Webb during these observations is likely one-fifth the area of the body itself. Webb’s high sensitivity, in combination with detailed models, may permit us to tease out the signature of the ring material distinct from that of Chariklo. Pinilla-Alonso commented that “by observing Chariklo with Webb over several years as the viewing angle of the rings changes, we may be able to isolate the contribution from the rings themselves.”
Our successful Webb occultation light curve and spectroscopic observations of Chariklo open the door to a new means of characterizing small objects in the distant solar system in the coming years. With Webb’s high sensitivity and infrared capability, scientists can use the unique science return offered by occultations, and enhance these measurements with near-contemporaneous spectra. Such tools will be tremendous assets to the scientists studying distant small bodies in our solar system.
The James Webb Space Telescope is the world’s largest, most powerful, and most complex space science telescope ever built. Webb will solve mysteries in our solar system, look beyond to distant worlds around other stars, and probe the mysterious structures and origins of our universe and our place in it. Webb is an international program led by NASA with its partners, ESA (European Space Agency) and the Canadian Space Agency.
Learn more about Webb at:
Volcano-like rupture could have caused magnetar slowdown
Star’s sudden 2020 slowdown allows for test of ‘anti-glitch’ theory
Peer-Reviewed PublicationIMAGE: AN ARTIST'S IMPRESSION OF A MAGNETAR ERUPTION. view more
CREDIT: IMAGE COURTESY OF NASA'S GODDARD SPACE FLIGHT CENTER
HOUSTON – (Jan. 27, 2023) – On Oct. 5, 2020, the rapidly rotating corpse of a long-dead star about 30,000 light years from Earth changed speeds. In a cosmic instant, its spinning slowed. And a few days later, it abruptly started emitting radio waves.
Thanks to timely measurements from specialized orbiting telescopes, Rice University astrophysicist Matthew Baring and colleagues were able to test a new theory about a possible cause for the rare slowdown, or “anti-glitch,” of SGR 1935+2154, a highly magnetic type of neutron star known as a magnetar.
In a study published this month in Nature Astronomy, Baring and co-authors used X-ray data from the European Space Agency’s X-ray Multi-Mirror Mission (XMM-Newton) and NASA’s Neutron Star Interior Composition Explorer (NICER) to analyze the magnetar’s rotation. They showed the sudden slowdown could have been caused by a volcano-like rupture on the surface of the star that spewed a “wind” of massive particles into space. The research identified how such a wind could alter the star’s magnetic fields, seeding conditions that would be likely to switch on the radio emissions that were subsequently measured by China’s Five-hundred-meter Aperture Spherical Telescope (FAST).
“People have speculated that neutron stars could have the equivalent of volcanoes on their surface,” said Baring, a professor of physics and astronomy. “Our findings suggest that could be the case and that on this occasion, the rupture was most likely at or near the star’s magnetic pole.”
SGR 1935+2154 and other magnetars are a type of neutron star, the compact remains of a dead star that collapsed under intense gravity. About a dozen miles wide and as dense as the nucleus of an atom, magnetars rotate once every few seconds and feature the most intense magnetic fields in the universe.
Magnetars emit intense radiation, including X-rays and occasional radio waves and gamma rays. Astronomers can decipher much about the unusual stars from those emissions. By counting pulses of X-rays, for example, physicists can calculate a magnetar’s rotational period, or the amount of time it takes to make one complete rotation, as the Earth does in one day. The rotational periods of magnetars typically change slowly, taking tens of thousands of years to slow by a single rotation per second.
Glitches are abrupt increases in rotational speed that are most often caused by sudden shifts deep within the star, Baring said.
“In most glitches, the pulsation period gets shorter, meaning the star spins a bit faster than it had been,” he said. “The textbook explanation is that over time, the outer, magnetized layers of the star slow down, but the inner, non-magnetized core does not. This leads to a buildup of stress at the boundary between these two regions, and a glitch signals a sudden transfer of rotational energy from the faster spinning core to the slower spinning crust.”
Abrupt rotational slowdowns of magnetars are very rare. Astronomers have only recorded three of the “anti-glitches,” including the October 2020 event.
While glitches can be routinely explained by changes inside the star, anti-glitches likely cannot. Baring’s theory is based on the assumption that they are caused by changes on the surface of the star and in the space around it. In the new paper, he and his co-authors constructed a volcano-driven wind model to explain the measured results from the October 2020 anti-glitch.
Baring said the model uses only standard physics, specifically changes in angular momentum and conservation of energy, to account for the rotational slowdown.
“A strong, massive particle wind emanating from the star for a few hours could establish the conditions for the drop in rotational period,” he said. “Our calculations showed such a wind would also have the power to change the geometry of the magnetic field outside the neutron star.”
The rupture could be a volcano-like formation, because “the general properties of the X-ray pulsation likely require the wind to be launched from a localized region on the surface,” he said.
“What makes the October 2020 event unique is that there was a fast radio burst from the magnetar just a few days after the anti-glitch, as well as a switch-on of pulsed, ephemeral radio emission shortly thereafter,” he said. “We’ve seen only a handful of transient pulsed radio magnetars, and this is the first time we’ve seen a radio switch-on of a magnetar almost contemporaneous with an anti-glitch.”
Baring argued this timing coincidence suggests the anti-glitch and radio emissions were caused by the same event, and he’s hopeful that additional studies of the volcanism model will provide more answers.
“The wind interpretation provides a path to understanding why the radio emission switches on,” he said. “It provides new insight we have not had before.”
The research was supported by the National Science Foundation (1813649), NASA (80NSSC22K0397), Japan’s RIKEN Advanced Science Institute and Taiwan’s Ministry of Science and Technology.
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Peer-reviewed study:
“'Magnetar spin-down glitch clearing the way for FRB-like bursts and a pulsed radio episode” | Nature Astronomy | DOI: 10.1038/s41550-022-01865-y
Authors: G. Younes, M.G. Baring, A.K. Harding, T. Enoto, Z. Wadiasingh, A.B. Pearlman, W.C.G. Ho, S. Guillot, Z. Arzoumanian, A. Borghese, K. Gendreau, E. Göğüş, T. Güver, A.J. van der Horst, C.-P. Hu, G. K. Jaisawal, C. Kouveliotou, L. Lin and W. A. Majid
https://www.nature.com/articles/s41550-022-01865-y
Images:
https://news-network.rice.edu/news/files/2023/01/0123_GLITCH-mb427-lg.jpg
CAPTION: Matthew Baring is a professor of physics and astronomy at Rice University. (Photo by Henry Baring, Lovett Class of 2020)
https://news-network.rice.edu/news/files/2023/01/0123_GLITCH-mag-lg.jpg
CAPTION: An artist's impression of a magnetar eruption. (Image courtesy of NASA's Goddard Space Flight Center)
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Fermi space telescope offers 'best look ever' at giant flare – Jan. 13, 2021
https://news.rice.edu/news/2021/fermi-space-telescope-offers-best-look-ever-giant-flare
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JOURNAL
Nature Astronomy
METHOD OF RESEARCH
Data/statistical analysis
SUBJECT OF RESEARCH
Not applicable
ARTICLE TITLE
Magnetar spin-down glitch clearing the way for FRB-like bursts and a pulsed radio episode
ARTICLE PUBLICATION DATE
12-Jan-2023
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