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By NASA
5 Min Read Webb Maps Full Picture of How Phoenix Galaxy Cluster Forms Stars
Spectroscopic data collected from NASA’s James Webb Space Telescope is overlayed on an image of the Phoenix cluster that combines data from NASA’s Hubble Space Telescope, Chandra X-ray Observatory and the Very Large Array (VLA) radio telescope. Credits:
NASA, CXC, NRAO, ESA, M. McDonald (MIT), M. Reefe (MIT), J. Olmsted (STScI) Discovery proves decades-old theory of galaxy feeding cycle.
Researchers using NASA’s James Webb Space Telescope have finally solved the mystery of how a massive galaxy cluster is forming stars at such a high rate. The confirmation from Webb builds on more than a decade of studies using NASA’s Chandra X-ray Observatory and Hubble Space Telescope, as well as several ground-based observatories.
The Phoenix cluster, a grouping of galaxies bound together by gravity 5.8 billion light-years from Earth, has been a target of interest for astronomers due to a few unique properties. In particular, ones that are surprising: a suspected extreme cooling of gas and a furious star formation rate despite a roughly 10 billion solar mass supermassive black hole at its core. In other observed galaxy clusters, the central supermassive black hole powers energetic particles and radiation that prevents gas from cooling enough to form stars. Researchers have been studying gas flows within this cluster to try to understand how it is driving such extreme star formation.
Image A: Phoenix Cluster (Hubble, Chandra, VLA Annotated)
Spectroscopic data collected from NASA’s James Webb Space Telescope is overlayed on an image of the Phoenix cluster that combines data from NASA’s Hubble Space Telescope, Chandra X-ray Observatory and the Very Large Array (VLA) radio telescope. Webb’s powerful sensitivity in the mid-infrared detected the cooling gas that leads to a furious rate of star formation in this massive galaxy cluster. Credit: NASA, CXC, NRAO, ESA, M. McDonald (MIT), M. Reefe (MIT), J. Olmsted (STScI) “We can compare our previous studies of the Phoenix cluster, which found differing cooling rates at different temperatures, to a ski slope,” said Michael McDonald of the Massachusetts Institute of Technology in Cambridge, principal investigator of the program. “The Phoenix cluster has the largest reservoir of hot, cooling gas of any galaxy cluster — analogous to having the busiest chair lift, bringing the most skiers to the top of the mountain. However, not all of those skiers were making it down the mountain, meaning not all the gas was cooling to low temperatures. If you had a ski slope where there were significantly more people getting off the ski lift at the top than were arriving at the bottom, that would be a problem!”
To date, in the Phoenix cluster, the numbers weren’t adding up, and researchers were missing a piece of the process. Webb has now found those proverbial skiers at the middle of the mountain, in that it has tracked and mapped the missing cooling gas that will ultimately feed star formation. Most importantly, this intermediary warm gas was found within cavities tracing the very hot gas, a searing 18 million degrees Fahrenheit, and the already cooled gas around 18,000 degrees Fahrenheit.
The team studied the cluster’s core in more detail than ever before with the Medium-Resolution Spectrometer on Webb’s Mid-Infrared Instrument (MIRI). This tool allows researchers to take two-dimenstional spectroscopic data from a region of the sky, during one set of observations.
“Previous studies only measured gas at the extreme cold and hot ends of the temperature distribution throughout the center of the cluster,” added McDonald. “We were limited — it was not possible to detect the ‘warm’ gas that we were looking for. With Webb, we could do this for the first time.”
Image B: Phoenix Cluster (Hubble, Chandra, VLA)
This image of the Phoenix cluster combines data from NASA’s Hubble Space Telescope, Chandra X-ray Observatory, and the Very Large Array radio telescope. X-rays from Chandra depict extremely hot gas in purple. Optical light data from Hubble show galaxies in yellow, and filaments of cooler gas where stars are forming in light blue. Outburst generated jets, represented in red, are seen in radio waves by the VLA radio telescope. NASA, CXC, NRAO, ESA, M. McDonald (MIT). A Quirk of Nature
Webb’s capability to detect this specific temperature of cooling gas, around 540,000 degrees Fahrenheit, is in part due to its instrumental capabilities. However, the researchers are getting a little help from nature, as well.
This oddity involves two very different ionized atoms, neon and oxygen, created in similar environments. At these temperatures, the emission from oxygen is 100 times brighter but is only visible in ultraviolet. Even though the neon is much fainter, it glows in the infrared, which allowed the researchers to take advantage of Webb’s advanced instruments.
“In the mid-infrared wavelengths detected by Webb, the neon VI signature was absolutely booming,” explained Michael Reefe, also of the Massachusetts Institute of Technology, lead author on the paper published in Nature. “Even though this emission is usually more difficult to detect, Webb’s sensitivity in the mid-infrared cuts through all of the noise.”
The team now hopes to employ this technique to study more typical galaxy clusters. While the Phoenix cluster is unique in many ways, this proof of concept is an important step towards learning about how other galaxy clusters form stars.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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Laura Betz – laura.e.betz@nasa.gov
NASA’s Goddard Space Flight Center, Greenbelt, Md.
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Space Telescope Science Institute, Baltimore, Md.
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Space Telescope Science Institute, Baltimore, Md.
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By NASA
u0022The really interesting thing to me is how time theoretically acts strangely around black holes. According to Albert Einstein’s theory of gravity, black holes change the flow of time,u0022 said Jeremy Schnittman, Goddard research astrophysicist. u0022So much of how we experience the world is based on time, time marching steadily forward. Anything that changes that is a fascinating take on reality.u0022u003cstrongu003eu003cemu003eCredits: NASA’s Goddard Space Flight Center / Rebecca Rothu003c/emu003eu003c/strongu003e Name: Jeremy Schnittman
Formal Job Classification: Research astrophysicist
Organization: Gravitational Astrophysics Laboratory, Astrophysics Division (Code 663)
What do you do and what is most interesting about your role here at Goddard? How do you help support Goddard’s mission?
I try to understand the formation and properties of black holes. I also help develop ideas for new missions to study black holes.
What drew you to astrophysics?
I always liked science and math. The great thing about astrophysics is that it involves a little bit of everything – math, computer programming, physics, chemistry and even philosophy to understand the big picture, the enormity of space.
I have a B.A. in physics from Harvard, and a Ph.D. in physics from MIT. I came to Goddard in 2010 after two post-doctoral fellowships.
Explore how the extreme gravity of two orbiting supermassive black holes distorts our view. In this visualization, disks of bright, hot, churning gas encircle both black holes, shown in red and blue to better track the light source. The red disk orbits the larger black hole, which weighs 200 million times the mass of our Sun, while its smaller blue companion weighs half as much. Zooming into each black hole reveals multiple, increasingly warped images of its partner. Watch to learn more.
Credits: NASA’s Goddard Space Flight Center/Jeremy Schnittman and Brian P. Powell
Download high-resolution video and images from NASA’s Scientific Visualization Studio As an astrophysicist, what do you think about?
I think of myself as a computational physicist as opposed to an experimental or observational physicist. I write many computer programs to do computer simulations of black holes. I also do a lot of theoretical physics, which is pencil and paper work. I think a lot about equations and math to understand black holes.
What is most philosophical about black holes to me is not so much what people most often think about, that their gravity is so strong that even light cannot escape. The really interesting thing to me is how time theoretically acts strangely around black holes. According to Albert Einstein’s theory of gravity, black holes change the flow of time. If you could get close enough to a black hole, theoretically you could go back and forth in time. All our experiments and observations seem to indicate that is how black holes might behave.
So much of how we experience the world is based on time, time marching steadily forward. Anything that changes that is a fascinating take on reality.
Related Link: Gravity Assist: Black Hole Mysteries, with Jeremy Schnittman What do you tell the people you mentor?
I mentor undergraduate, graduate, and post graduate students in astrophysics. Since we are working remotely, I have students from all over the country. I help them with their research projects which mostly relate to black holes in some way. I also offer career advice and help them with their work-life balance. When possible, family comes first.
There are more people coming out of graduate school in astrophysics than there are jobs, so there are going to be many people who will not work for NASA or as a professor. Fortunately, there are a lot of other fascinating, related jobs, and I help guide the students there.
What do you do for fun?
I have a woodshop in our basement where I build furniture, dollhouses, toys, and other items for gifts. As a theoretical physicist, I don’t get to work in a lab. So it is nice to have some hands on experience.
I do a lot of hiking and cycling to exercise. I also enjoy spending time with my family.
Who is your favorite author?
Andy Weir is probably my favorite sci-fi author. I also love the epic naval historical fiction by Patrick O’Brian.
Who inspires you?
My childhood hero, who is still my scientific hero, is Albert Einstein. The more I work in astrophysics, the more he impresses me. Every single one of his predictions that we have been able to test has proven true. It may be a while, but someday I hope we prove his theories about time travel.
Also, I admire Kip Thorne, an American physicist from Cal Tech and recent Nobel laureate, who is “the man” when it comes to black holes. He is also a really nice, good guy, a real mensch. Very humble and down-to-earth. He is always extremely patient, kind and encouraging especially to the younger scientists. He is a good role model as I transition from junior to more senior status.
What is your one big dream?
I make a lot of predictions, so it would be exciting if one of my theories was proven correct. Hopefully someday.
By Elizabeth M. Jarrell
NASA’s Goddard Space Flight Center, Greenbelt, Md.
Conversations with Goddard Conversations With Goddard is a collection of question and answer profiles highlighting the breadth and depth of NASA’s Goddard Space Flight Center’s talented and diverse workforce. The Conversations have been published twice a month on average since May 2011. Read past editions on Goddard’s “Our People” webpage.
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By NASA
NASA’s Dawn spacecraft captured this image of Vesta as it left the giant asteroid’s orbit in 2012. The framing camera was looking down at the north pole, which is in the middle of the image.NASA/JPL-Caltech/UCLA/MPS/DLR/IDA Known as flow formations, these channels could be etched on bodies that would seem inhospitable to liquid because they are exposed to the extreme vacuum conditions of space.
Pocked with craters, the surfaces of many celestial bodies in our solar system provide clear evidence of a 4.6-billion-year battering by meteoroids and other space debris. But on some worlds, including the giant asteroid Vesta that NASA’s Dawn mission explored, the surfaces also contain deep channels, or gullies, whose origins are not fully understood.
A prime hypothesis holds that they formed from dry debris flows driven by geophysical processes, such as meteoroid impacts, and changes in temperature due to Sun exposure. A recent NASA-funded study, however, provides some evidence that impacts on Vesta may have triggered a less-obvious geologic process: sudden and brief flows of water that carved gullies and deposited fans of sediment. By using lab equipment to mimic conditions on Vesta, the study, which appeared in Planetary Science Journal, detailed for the first time what the liquid could be made of and how long it would flow before freezing.
Although the existence of frozen brine deposits on Vesta is unconfirmed, scientists have previously hypothesized that meteoroid impacts could have exposed and melted ice that lay under the surface of worlds like Vesta. In that scenario, flows resulting from this process could have etched gullies and other surface features that resemble those on Earth.
To explore potential explanations for deep channels, or gullies, seen on Vesta, scientists used JPL’s Dirty Under-vacuum Simulation Testbed for Icy Environments, or DUSTIE, to simulate conditions on the giant asteroid that would occur after meteoroids strike the surface.NASA/JPL-Caltech But how could airless worlds — celestial bodies without atmospheres and exposed to the intense vacuum of space — host liquids on the surface long enough for them to flow? Such a process would run contrary to the understanding that liquids quickly destabilize in a vacuum, changing to a gas when the pressure drops.
“Not only do impacts trigger a flow of liquid on the surface, the liquids are active long enough to create specific surface features,” said project leader and planetary scientist Jennifer Scully of NASA’s Jet Propulsion Laboratory in Southern California, where the experiments were conducted. “But for how long? Most liquids become unstable quickly on these airless bodies, where the vacuum of space is unyielding.”
The critical component turns out to be sodium chloride — table salt. The experiments found that in conditions like those on Vesta, pure water froze almost instantly, while briny liquids stayed fluid for at least an hour. “That’s long enough to form the flow-associated features identified on Vesta, which were estimated to require up to a half-hour,” said lead author Michael J. Poston of the Southwest Research Institute in San Antonio.
Launched in 2007, the Dawn spacecraft traveled to the main asteroid belt between Mars and Jupiter to orbit Vesta for 14 months and Ceres for almost four years. Before ending in 2018, the mission uncovered evidence that Ceres had been home to a subsurface reservoir of brine and may still be transferring brines from its interior to the surface. The recent research offers insights into processes on Ceres but focuses on Vesta, where ice and salts may produce briny liquid when heated by an impact, scientists said.
Re-creating Vesta
To re-create Vesta-like conditions that would occur after a meteoroid impact, the scientists relied on a test chamber at JPL called the Dirty Under-vacuum Simulation Testbed for Icy Environments, or DUSTIE. By rapidly reducing the air pressure surrounding samples of liquid, they mimicked the environment around fluid that comes to the surface. Exposed to vacuum conditions, pure water froze instantly. But salty fluids hung around longer, continuing to flow before freezing.
The brines they experimented with were a little over an inch (a few centimeters) deep; scientists concluded the flows on Vesta that are yards to tens of yards deep would take even longer to refreeze.
The researchers were also able to re-create the “lids” of frozen material thought to form on brines. Essentially a frozen top layer, the lids stabilize the liquid beneath them, protecting it from being exposed to the vacuum of space — or, in this case the vacuum of the DUSTIE chamber — and helping the liquid flow longer before freezing again.
This phenomenon is similar to how on Earth lava flows farther in lava tubes than when exposed to cool surface temperatures. It also matches up with modeling research conducted around potential mud volcanoes on Mars and volcanoes that may have spewed icy material from volcanoes on Jupiter’s moon Europa.
“Our results contribute to a growing body of work that uses lab experiments to understand how long liquids last on a variety of worlds,” Scully said.
Find more information about NASA’s Dawn mission here:
https://science.nasa.gov/mission/dawn/
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Gretchen McCartney
Jet Propulsion Laboratory, Pasadena, Calif.
818-287-4115
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Karen Fox / Molly Wasser
NASA Headquarters, Washington
202-358-1600
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Last Updated Dec 20, 2024 Related Terms
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By NASA
NASA has taken a big step forward in how engineers will assemble and stack future SLS (Space Launch System) rockets for Artemis Moon missions inside the Vehicle Assembly Building (VAB) at the agency’s Kennedy Space Center in Florida.
The VAB’s High Bay 2 has been outfitted with new tooling to facilitate the vertical integration of the SLS core stage. That progress was on full display in mid-December when teams suspended the fully assembled core stage 225 feet in the air inside the high bay to complete vertical work before it is stacked on mobile launcher 1, allowing teams to continue solid rocket booster stacking simultaneously inside High Bay 3 for Artemis II.
The fully assembled SLS (Space Launch System) core stage for the Artemis II test flight is suspended 225 feet in the air inside the newly renovated High Bay 2 at Kennedy’s Vehicle Assembly Building. The core stage was lifted to enable engineers to complete work before it is stacked on mobile launcher 1 with other rocket elements. With the move to High Bay 2, technicians now have 360-degree tip to tail access to the core stage, both internally and externally.NASA With the move to High Bay 2, technicians with NASA and Boeing now have 360-degree tip to tail access to the core stage, both internally and externally. Michigan-based supplier Futuramic Tool and Engineering led the design and build of the Core Stage Vertical Integration Center tool that will hold the core stage in a vertical position.
“High Bay 2 tooling was originally scheduled to be complete for Artemis III. We had an opportunity to get it done earlier and that will put us in a good posture to complete work earlier than planned prior to moving the core stage for Artemis II into the full integrated stack over into in High Bay 3,” said Chad Bryant, deputy manager of the NASA SLS Stages Office. “This gives us an opportunity to go in and learn how to rotate, lift, and move the core stage into the high bay.”
This move also doubles the footprint of useable space within the VAB, giving engineers access to both High Bay 2 and High Bay 3 simultaneously, while also freeing up space at NASA’s Michoud Assembly Facility in New Orleans to continue work on the individual elements for future SLS core stages.
High Bay 2 has a long history of supporting NASA exploration programs: during Apollo, High Bay 2, one of four high bays inside the VAB, was used to stack the Saturn V rocket. During the Space Shuttle Program, the high bay was used for external tank checkout and storage and as an extra storage area for the shuttle.
Under the new assembly model beginning with Artemis III, all the major structures for the SLS core stage will continue to be fully produced and manufactured at NASA Michoud. Upon completion of manufacturing and thermal protection system application, the engine section will be shipped to Kennedy for final outfitting.
The 212-foot-tall SLS (Space Launch System) core stage for NASA Artemis II is seen being moved from a horizontal position to a vertical position in High Bay 2 at the Vehicle Assembly Building at NASA’s Kennedy Space Center in Florida. With the move to High Bay 2, NASA and Boeing technicians now have 360-degree access to the core stage both internally and externally. (NASA) “Core stage 3 marks a significant change in the way we build core stages,” said Steve Wofford, manager of the SLS Stages Office. “The vertical capability in High Bay 2 allows us to perform parallel processing from the top to bottom of the stage. It’s a much more efficient way to build core stages. This new capability will streamline final production efforts, allowing our team to have 360-degree access to the stage, both internally and externally.”
The fully assembled core stage for Artemis II arrived July 23, 2024, at Kennedy, where it remained horizontal inside the VAB transfer aisle until its recent lift into the newly outfitted high bay.
Teams at NASA Michoud are outfitting the remaining core stage elements for Artemis III and preparing to horizontally join them. The four RS-25 engines for the Artemis III mission are complete at NASA’s Stennis Space Center in Bay St. Louis, Mississippi, and will be transported to NASA Kennedy in 2025. Major core stage and exploration upper stage structures are in work at NASA Michoud for Artemis IV and beyond.
NASA is working to land the first woman, first person of color, and its first international partner astronaut on the Moon under Artemis. SLS is part of NASA’s backbone for deep space exploration, along with the Orion spacecraft, supporting ground systems, advanced spacesuits and rovers, the Gateway in orbit around the Moon, and commercial human landing systems. SLS is the only rocket that can send Orion, astronauts, and supplies to the Moon in a single launch.
News Media Contact
Jonathan Deal
Marshall Space Flight Center
Huntsville, Ala.
256-544-0034
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By NASA
Download PDF: Statistical Analysis Using Random Forest Algorithm Provides Key Insights into Parachute Energy Modulator System
Energy modulators (EM), also known as energy absorbers, are safety-critical components that are used to control shocks and impulses in a load path. EMs are textile devices typically manufactured out of nylon, Kevlar® and other materials, and control loads by breaking rows of stitches that bind a strong base webbing together as shown in Figure 1. A familiar EM application is a fall-protection harness used by workers to prevent injury from shock loads when the harness arrests a fall. EMs are also widely used in parachute systems to control shock loads experienced during the various stages of parachute system deployment.
Random forest is an innovative algorithm for data classification used in statistics and machine learning. It is an easy to use and highly flexible ensemble learning method. The random forest algorithm is capable of modeling both categorical and continuous data and can handle large datasets, making it applicable in many situations. It also makes it easy to evaluate the relative importance of variables and maintains accuracy even when a dataset has missing values.
Random forests model the relationship between a response variable and a set of predictor or independent variables by creating a collection of decision trees. Each decision tree is built from a random sample of the data. The individual trees are then combined through methods such as averaging or voting to determine the final prediction (Figure 2). A decision tree is a non-parametric supervised learning algorithm that partitions the data using a series of branching binary decisions. Decision trees inherently identify key features of the data and provide a ranking of the contribution of each feature based on when it becomes relevant. This capability can be used to determine the relative importance of the input variables (Figure 3). Decision trees are useful for exploring relationships but can have poor accuracy unless they are combined into random forests or other tree-based models.
The performance of a random forest can be evaluated using out-of-bag error and cross-validation techniques. Random forests often use random sampling with replacement from the original dataset to create each decision tree. This is also known as bootstrap sampling and forms a bootstrap forest. The data included in the bootstrap sample are referred to as in-the-bag, while the data not selected are out-of-bag. Since the out-of-bag data were not used to generate the decision tree, they can be used as an internal measure of the accuracy of the model. Cross-validation can be used to assess how well the results of a random forest model will generalize to an independent dataset. In this approach, the data are split into a training dataset used to generate the decision trees and build the model and a validation dataset used to evaluate the model’s performance. Evaluating the model on the independent validation dataset provides an estimate of how accurately the model will perform in practice and helps avoid problems such as overfitting or sampling bias. A good model performs well on
both the training data and the validation data.
The complex nature of the EM system made it difficult for the team to identify how various parameters influenced EM behavior. A bootstrap forest analysis was applied to the test dataset and was able to identify five key variables associated with higher probability of damage and/or anomalous behavior. The identified key variables provided a basis for further testing and redesign of the EM system. These results also provided essential insight to the investigation and aided in development of flight rationale for future use cases.
For information, contact Dr. Sara R. Wilson. sara.r.wilson@nasa.gov
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