SPACE
NASA’s Webb images cold exoplanet 12 light-years away
An international team of astronomers using NASA’s James Webb Space Telescope has directly imaged an exoplanet roughly 12 light-years from Earth. The planet, Epsilon Indi Ab, is one of the coldest exoplanets observed to date.
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THIS IMAGE OF THE GAS-GIANT EXOPLANET EPSILON INDI AB WAS TAKEN WITH THE CORONAGRAPH ON NASA’S JAMES WEBB SPACE TELESCOPE’S MIRI (MID-INFRARED INSTRUMENT). A STAR SYMBOL MARKS THE LOCATION OF THE HOST STAR EPSILON INDI A, WHOSE LIGHT HAS BEEN BLOCKED BY THE CORONAGRAPH, RESULTING IN THE DARK CIRCLE MARKED WITH A DASHED WHITE LINE. EPSILON INDI AB IS ONE OF THE COLDEST EXOPLANETS EVER DIRECTLY IMAGED. LIGHT AT 10.6 MICRONS WAS ASSIGNED THE COLOR BLUE, WHILE LIGHT AT 15.5 MICRONS WAS ASSIGNED THE COLOR ORANGE. MIRI DID NOT RESOLVE THE PLANET, WHICH IS A POINT SOURCE.
view moreCREDIT: NASA, ESA, CSA, STSCI, E. MATTHEWS (MAX PLANCK INSTITUTE FOR ASTRONOMY)
An international team of astronomers using NASA’s James Webb Space Telescope has directly imaged an exoplanet roughly 12 light-years from Earth. The planet, Epsilon Indi Ab, is one of the coldest exoplanets observed to date.
The planet is several times the mass of Jupiter and orbits the K-type star Epsilon Indi A (Eps Ind A), which is around the age of our Sun, but slightly cooler. The team observed Epsilon Indi Ab using the coronagraph on Webb’s MIRI (Mid-Infrared Instrument). Only a few tens of exoplanets have been directly imaged previously by space- and ground-based observatories.
“Our prior observations of this system have been more indirect measurements of the star, which actually allowed us to see ahead of time that there was likely a giant planet in this system tugging on the star,” said team member Caroline Morley of the University of Texas at Austin. “That's why our team chose this system to observe first with Webb.”
“This discovery is exciting because the planet is quite similar to Jupiter — it is a little warmer and is more massive, but is more similar to Jupiter than any other planet that has been imaged so far,” added lead author Elisabeth Matthews of the Max Planck Institute for Astronomy in Germany.
Previously imaged exoplanets tend to be the youngest, hottest exoplanets that are still radiating much of the energy from when they first formed. As planets cool and contract over their lifetime, they become significantly fainter and therefore harder to image.
A Solar System Analog
“Cold planets are very faint, and most of their emission is in the mid-infrared,” explained Matthews. “Webb is ideally suited to conduct mid-infrared imaging, which is extremely hard to do from the ground. We also needed good spatial resolution to separate the planet and the star in our images, and the large Webb mirror is extremely helpful in this aspect.”
Epsilon Indi Ab is one of the coldest exoplanets to be directly detected, with an estimated temperature of 35 degrees Fahrenheit (2 degrees Celsius) — colder than any other imaged planet beyond our solar system, and colder than all but one free-floating brown dwarf. The planet is only around 180 degrees Fahrenheit (100 degrees Celsius) warmer than gas giants in our solar system. This provides a rare opportunity for astronomers to study the atmospheric composition of true solar system analogs.
“Astronomers have been imagining planets in this system for decades; fictional planets orbiting Epsilon Indi have been the sites of Star Trek episodes, novels, and video games like Halo,” added Morley. “It's exciting to actually see a planet there ourselves, and begin to measure its properties.”
Not Quite As Predicted
Epsilon Indi Ab is the twelfth closest exoplanet to Earth known to date and the closest planet more massive than Jupiter. The science team chose to study Eps Ind A because the system showed hints of a possible planetary body using a technique called radial velocity, which measures the back-and-forth wobbles of the host star along our line of sight.
“While we expected to image a planet in this system, because there were radial velocity indications of its presence, the planet we found isn’t what we had predicted,” shared Matthews. “It’s about twice as massive, a little farther from its star, and has a different orbit than we expected. The cause of this discrepancy remains an open question. The atmosphere of the planet also appears to be a little different than the model predictions. So far we only have a few photometric measurements of the atmosphere, meaning that it is hard to draw conclusions, but the planet is fainter than expected at shorter wavelengths.”
The team believes this may mean there is significant methane, carbon monoxide, and carbon dioxide in the planet’s atmosphere that are absorbing the shorter wavelengths of light. It might also suggest a very cloudy atmosphere.
The direct imaging of exoplanets is particularly valuable for characterization. Scientists can directly collect light from the observed planet and compare its brightness at different wavelengths. So far, the science team has only detected Epsilon Indi Ab at a few wavelengths, but they hope to revisit the planet with Webb to conduct both photometric and spectroscopic observations in the future. They also hope to detect other similar planets with Webb to find possible trends about their atmospheres and how these objects form.
NASA's upcoming Nancy Grace Roman Space Telescope will use a coronagraph to demonstrate direct imaging technology by photographing Jupiter-like worlds orbiting Sun-like stars – something that has never been done before. These results will pave the way for future missions to study worlds that are even more Earth-like.
These results were taken with Webb’s Cycle 1 General Observer program 2243 and have been published in the journal Nature.
The James Webb Space Telescope is the world’s premier space science observatory. Webb is solving mysteries in our solar system, looking beyond to distant worlds around other stars, and probing 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 CSA (Canadian Space Agency).
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JOURNAL
Nature
ARTICLE TITLE
A temperate super-Jupiter imaged with JWST in the mid-infrared
ARTICLE PUBLICATION DATE
24-Jul-2024
Dark matter flies ahead of normal matter in mega galaxy cluster collision
The research provides a unique look at how this matter decoupling proceeds
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THIS ARTIST'S CONCEPT SHOWS WHAT HAPPENED WHEN TWO MASSIVE CLUSTERS OF GALAXIES, COLLECTIVELY KNOWN AS MACS J0018.5, COLLIDED: THE DARK MATTER IN THE GALAXY CLUSTERS (BLUE) SAILED AHEAD OF THE ASSOCIATED CLOUDS OF HOT GAS, OR NORMAL MATTER (ORANGE). BOTH DARK MATTER AND NORMAL MATTER FEEL THE PULL OF GRAVITY, BUT ONLY THE NORMAL MATTER EXPERIENCES ADDITIONAL EFFECTS LIKE SHOCKS AND TURBULENCE THAT SLOW IT DOWN DURING COLLISIONS.
view moreCREDIT: W.M. KECK OBSERVATORY/ADAM MAKARENKO
Astronomers have untangled a messy collision between two massive clusters of galaxies in which the clusters' vast clouds of dark matter have decoupled from the so-called normal matter. The two clusters each contain thousands of galaxies and are located billions of light-years away from Earth. As they plowed through each other, the dark matter—an invisible substance that feels the force of gravity but emits no light—sped ahead of the normal matter. The new observations are the first to directly probe the decoupling of the dark and normal matter velocities.
Galaxy clusters are among the largest structures in the universe, glued together by the force of gravity. Only 15 percent of the mass in such clusters is normal matter, the same matter that makes up planets, people, and everything you see around you. Of this normal matter, the vast majority is hot gas, while the rest is stars and planets. The remaining 85 percent of the cluster mass is dark matter.
During the tussle that took place between the clusters, known collectivity as MACS J0018.5+1626, the individual galaxies themselves largely went unscathed because so much space exists between them. But when the enormous stores of gas between the galaxies (the normal matter) collided, the gas became turbulent and superheated. While all matter, including both normal matter and dark matter, interacts via gravity, the normal matter also interacts via electromagnetism, which slows it down during a collision. So, while the normal matter became bogged down, the pools of dark matter within each cluster sailed on through.
Think of a massive collision between multiple dump trucks carrying sand, suggests Emily Silich, lead author of a new study describing the findings in The Astrophysical Journal. "The dark matter is like the sand and flies ahead." Silich is a graduate student working with Jack Sayers, research professor of physics at Caltech and principal investigator of the study.
The discovery was made using data from the Caltech Submillimeter Observatory (which was recently removed from its site on Maunakea in Hawai‘i and will be relocated to Chile), the W.M. Keck Observatory on Maunakea, NASA's Chandra X-ray Observatory, NASA's Hubble Space Telescope, the European Space Agency's now-retired Herschel Space Observatory and Planck observatory (whose affiliated NASA science centers were based at Caltech's IPAC), and the Atacama Submillimeter Telescope Experiment in Chile. Some of the observations were made decades ago, while the full analysis using all the datasets took place over the past couple of years.
Such decoupling of dark and normal matter has been seen before, most famously in the Bullet Cluster. In that collision, the hot gas can be seen clearly lagging behind the dark matter after the two galaxy clusters shot through each other. The situation that took place in MACS J0018.5+1626 (referred to subsequently as MACS J0018.5) is similar, but the orientation of the merger is rotated, roughly 90 degrees relative to that of the Bullet Cluster. In other words, one of the massive clusters in MACS J0018.5 is flying nearly straight toward Earth while the other one is rushing away. That orientation gave researchers a unique vantagepoint from which to, for the first time, map out the velocity of both the dark matter and normal matter and elucidate how they decouple from each other during a galaxy cluster collision.
"With the Bullet Cluster, it's like we are sitting in a grandstand watching a car race and are able to capture beautiful snapshots of the cars moving from left to right on the straightaway," says Sayers. "In our case, it's more like we are on the straightaway with a radar gun, standing in front of a car as it comes at us and are able to obtain its speed."
To measure the speed of the normal matter, or gas, in the cluster, researchers used an observational method known as the kinetic Sunyaev-Zel'dovich (SZ) effect. Sayers and his colleagues made the first observational detection of the kinetic SZ effect on an individual cosmic object, a galaxy cluster named MACS J0717, back in 2013, using data from CSO (the first SZ effect observations taken of MACS J0018.5 date back to 2006).
The kinetic SZ effect occurs when photons from the early universe, the cosmic microwave background (CMB), scatter off electrons in hot gas on their way toward us on Earth. The photons undergo a shift, called a Doppler shift, due to the motions of the electrons in the gas clouds along our line of sight. By measuring the change in brightness of the CMB due to this shift, researchers can determine the speed of gas clouds within galaxy clusters.
"The Sunyaev-Zeldovich effects were still a very new observational tool when Jack and I first turned a new camera at the CSO on galaxy clusters in 2006, and we had no idea there would be discoveries like this," says Sunil Golwala, professor of physics and Silich's faculty PhD advisor. "We look forward to a slew of new surprises when we put next-generation instruments on the telescope at its new home in Chile."
By 2019, the researchers had made these kinetic SZ measurements in several galaxy clusters, which told them the speed of the gas, or normal matter. They had also used Keck to learn the speed of the galaxies in the cluster, which told them by proxy the speed of the dark matter (because the dark matter and galaxies behave similarly during the collision). But at this stage in the research, the team had a limited understanding of the orientations of the clusters. They only knew that one of them, MACS J0018.5, showed signs of something strange going on—the hot gas, or normal matter, was traveling in the opposite direction to the dark matter.
"We had this complete oddball with velocities in opposite directions, and at first we thought it could be a problem with our data. Even our colleagues who simulate galaxy clusters didn't know what was going on," Sayers says. "And then Emily got involved and untangled everything."
For part of her PhD thesis, Silich tackled the conundrum of MACS J0018.5. She turned to data from the Chandra X-ray Observatory to reveal the temperature and location of the gas in the clusters as well as the degree to which the gas was being shocked. "These cluster collisions are the most energetic phenomena since the Big Bang," Silich says. "Chandra measures the extreme temperatures of the gas and tells us about the age of the merger and how recently the clusters collided." The team also worked with Adi Zitrin of the Ben-Gurion University of the Negev in Israel to use Hubble data to map the dark matter using a method known as gravitational lensing.
Additionally, John ZuHone of the Center for Astrophysics at Harvard & Smithsonian helped the team simulate the cluster smashup. These simulations were used in combination with data from the various telescopes to ultimately determine the geometry and evolutionary stage of the cluster encounter. The scientists found that, prior to colliding, the clusters were moving toward each other at approximately 3000 kilometers/second, equal to roughly one percent of the speed of light. With a more complete picture of what was going on, the researchers were able to figure out why the dark matter and normal matter appeared to be traveling in opposite directions. Though the scientists say it's hard to visualize, the orientation of the collision, coupled with the fact that dark matter and normal matter had separated from each other, explains the oddball velocity measurements.
In the future, the researchers hope that more studies like this one will lead to new clues about the mysterious nature of dark matter. "This study is a starting point to more detailed studies into the nature of dark matter," Silich says. "We have a new type of direct probe that shows how dark matter behaves differently from normal matter."
Sayers, who recalls first collecting the CSO data on this object almost 20 years ago, says, "It took us a long time to put all the puzzle pieces together, but now we finally know what's going on. We hope this leads to a whole new way to study dark matter in clusters."
The study titled "ICM-SHOX. Paper I: Methodology overview and discovery of a gas–dark matter velocity decoupling in the MACS J0018.5+1626 merger," was funded by the National Science Foundation, the Wallace L. W. Sargent Graduate Fellowship at Caltech, the Chandra X-ray Center, the United States-Israel Binational Science Foundation, the Ministry of Science & Technology in Israel, the AtLAST (Atacama Large Aperture Submillimeter Telescope) project, and the Consejo Nacional de Humanidades Ciencias y Technologías.
JOURNAL
The Astrophysical Journal
Another intermediate-mass black hole discovered at the centre of our galaxy
UNIVERSITY OF COLOGNE
IMAGE:
DR FLORIAN PEISSGER
view moreCREDIT: LUDOLF DAHMEN | UNIVERSITY OF COLOGNE
While researching a cluster of stars in the immediate vicinity of the supermassive black hole SgrA* (Sagittarius A*) at the centre of our galaxy, an international team of researchers led by PD Dr Florian Peißker has found signs of another, intermediate-mass black hole. Despite enormous research efforts, only about ten of these intermediate-mass black holes have been found in our entire universe so far. Scientists believe that they formed shortly after the Big Bang. By merging, they act as ‘seeds’ for supermassive black holes. The study ‘The Evaporating Massive Embedded Stellar Cluster IRS 13 Close to Sgr A*. II. Kinematic structure’ was published in The Astrophysical Journal.
The analysed star cluster IRS 13 is located 0.1 light years from the centre of our galaxy. This is very close in astronomical terms, but would still require travelling from one end of our solar system to the other twenty times to cover the distance. The researchers noticed that the stars in IRS 13 move in an unexpectedly orderly pattern. They had actually expected the stars to be arranged randomly. Two conclusions can be drawn from this regular pattern: On the one hand, IRS 13 appears to interact with SgrA*, which leads to the orderly motion of the stars. On the other hand, there must be something inside the cluster for it to be able to maintain its observed compact shape.
Multi-wavelength observations with the Very Large Telescope as well as the ALMA and Chandra telescopes now suggest that the reason for the compact shape of IRS 13 could be an intermediate-mass black hole located at the centre of the star cluster. This would be supported by the fact that the researchers were able to observe characteristic X-rays and ionized gas rotating at a speed of several 100 km/s in a ring around the suspected location of the intermediate-mass black hole.
Another indication of the presence of an intermediate-mass black hole is the unusually high density of the star cluster, which is higher than that of any other known density of a star cluster in our Milky Way. “IRS 13 appears to be an essential building block for the growth of our central black hole SgrA*,” said Florian Peißker, first author of the study. “This fascinating star cluster has continued to surprise the scientific community ever since it was discovered around twenty years ago. At first it was thought to be an unusually heavy star. With the high-resolution data, however, we can now confirm the building-block composition with an intermediate-mass black hole at the centre.” Planned observations with the James Webb Space Telescope and the Extremely Large Telescope, which is currently under construction, will provide further insights into the processes within the star cluster.
JOURNAL
The Astrophysical Journal
METHOD OF RESEARCH
Imaging analysis
SUBJECT OF RESEARCH
Not applicable
ARTICLE TITLE
The Evaporating Massive Embedded Stellar Cluster IRS 13 Close to Sgr A*. II. Kinematic structure
ARTICLE PUBLICATION DATE
18-Jul-2024
Exoplanet-hunting telescope to begin search for another Earth in 2026
IMAGE:
AN ARTIST'S IMPRESSION OF THE EUROPEAN SPACE AGENCY'S PLATO SPACECRAFT.
view moreCREDIT: ESA/ATG MEDIALAB
Exoplanet-hunting telescope to begin search for another Earth in 2026
Royal Astronomical Society press release
RAS PR 24/20 (NAM 6)
For immediate release
Europe's next big space mission - a telescope that will hunt for Earth-like rocky planets outside of our solar system - is on course to launch at the end of 2026.
PLATO, or PLAnetary Transits and Oscillations of stars, is being built to find nearby potentially habitable worlds around Sun-like stars that we can examine in detail.
The space telescope will blast into orbit on Europe's new rocket, Ariane-6, which made its maiden flight last week after being developed at a cost of €4billion (£3.4billion).
Dr David Brown, of the University of Warwick, is giving an update on the mission at the Royal Astronomical Society's National Astronomy Meeting at the University of Hull this week.
"PLATO's goal is to search for exoplanets around stars similar to the Sun and at orbital periods long enough for them to be in the habitable zone," he said.
"One of the main mission objectives is to find another Earth-Sun equivalent pair, but it is also designed to carefully and precisely characterise the exoplanets that it finds (i.e. work out their masses, radii, and bulk density)."
PLATO isn't just an exoplanet hunter, however. It is also a stellar science mission.
As well as searching for exoplanets it will study the stars using a range of techniques including asteroseismology (measuring the vibrations and oscillations of stars) to work out their masses, radii, and ages.
Unlike most space telescopes, PLATO has multiple cameras – including a UK-named one called ArthurEddington, after the famous astronomer and physicist who won the Royal Astronomical Society's prestigious Gold Medal in 1924.
It has 24 'Normal' cameras (N-CAMs) and 2 'Fast' cameras (F-CAMs). The N-CAMs are arranged into four groups of six cameras, with the cameras in each group pointing in the same direction but the groups slightly offset.
This gives PLATO a very large field of view, improved scientific performance, redundancy against failures, and a built-in way to identify 'false positive' signals that might mimic an exoplanet transit, Dr Brown explained.
"The planned observing strategy is to stare at two patches of sky, one in the North and one in the South, for two years each," he added.
"The Southern patch of sky has been chosen, while the Northern patch won't be confirmed for another few years."
Several of the spacecraft's components have finished their manufacturing programmes and are close to completing their calibration tests. This includes the UK-provided Front-End Electronics (FEE) for the N-CAMs.
Built by the Mullard Space Science Laboratory of University College London, these operate the cameras, digitise the images, and transfer them to the onboard data processing.
Ten of the final cameras have been built and tested and the first of these was mounted onto the optical bench - the surface which keeps all cameras pointed in the right direction - earlier this year.
The mission is on track to launch in December 2026.
Ten of the final cameras have been built and tested and the first of these was mounted onto the optical bench - the surface which keeps all cameras pointed in the right direction - earlier this year.
Media contacts
Sam Tonkin
Royal Astronomical Society
Mob +44 (0)7802 877 700
Dr Robert Massey
Royal Astronomical Society
Mob: +44 (0)7802 877 699
Megan Eaves
Royal Astronomical Society
Science contacts
Dr David Brown
University of Warwick
Images and captions
Caption: An artist's impression of the European Space Agency's PLATO spacecraft.
Credit: ESA/ATG medialab
Caption: An animation of PLATO, showing different elements of the telescope including its payload of 26 cameras, the sunshield and solar panels.
Credit: ESA/ATG medialab
Caption: Unlike most space telescopes, PLATO has multiple cameras – including a UK-named one called ArthurEddington, after the famous astronomer and physicist who won the Royal Astronomical Society's Gold Medal in 1924.
Credit: OHB
Caption: Ten of the final cameras have been built and tested and the first of these was mounted onto the optical bench - the surface which keeps all cameras pointed in the right direction - earlier this year.
Credit: OHB System AG
Notes for editors
The NAM 2024 conference is principally sponsored by the Royal Astronomical Society, the Science and Technology Facilities Council and the University of Hull.
About the Royal Astronomical Society
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The Science and Technology Facilities Council (STFC) is part of UK Research and Innovation – the UK body which works in partnership with universities, research organisations, businesses, charities, and government to create the best possible environment for research and innovation to flourish.
STFC funds and supports research in particle and nuclear physics, astronomy, gravitational research and astrophysics, and space science and also operates a network of five national laboratories, including the Rutherford Appleton Laboratory and the Daresbury Laboratory, as well as supporting UK research at a number of international research facilities including CERN, FERMILAB, the ESO telescopes in Chile and many more.
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The E.A. Milne Centre for Astrophysics at the University of Hull brings together experts who study the evolution of structure in the Universe ranging from stars through to galaxies and galaxy clusters, right up to the largest structures in the cosmos.
The centre employs observations, theory and computational methods in collaboration with international partners. Postgraduate and undergraduate students work alongside staff to understand the wonders of the Universe. Through a series of outreach activities, the centre also aims to share its passion for astronomy and astrophysics with the region and beyond.
