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By NASA
5 Min Read Webb Finds Early Galaxies Weren’t Too Big for Their Britches After All
This image shows a small portion of the field observed by NASA’s James Webb Space Telescope’s NIRCam (Near-Infrared Camera) for the Cosmic Evolution Early Release Science (CEERS) survey. The full image appears below. Credits:
NASA, ESA, CSA, S. Finkelstein (University of Texas) It got called the crisis in cosmology. But now astronomers can explain some surprising recent discoveries.
When astronomers got their first glimpses of galaxies in the early universe from NASA’s James Webb Space Telescope, they were expecting to find galactic pipsqueaks, but instead they found what appeared to be a bevy of Olympic bodybuilders. Some galaxies appeared to have grown so massive, so quickly, that simulations couldn’t account for them. Some researchers suggested this meant that something might be wrong with the theory that explains what the universe is made of and how it has evolved since the big bang, known as the standard model of cosmology.
According to a new study in the Astrophysical Journal led by University of Texas at Austin graduate student Katherine Chworowsky, some of those early galaxies are in fact much less massive than they first appeared. Black holes in some of these galaxies make them appear much brighter and bigger than they really are.
“We are still seeing more galaxies than predicted, although none of them are so massive that they ‘break’ the universe,” Chworowsky said.
The evidence was provided by Webb’s Cosmic Evolution Early Release Science (CEERS) Survey, led by Steven Finkelstein, a professor of astronomy at UT Austin and study co-author.
Image A : CEERS Deep Field (NIRCam)
This image shows a small portion of the field observed by NASA’s James Webb Space Telescope’s NIRCam (Near-Infrared Camera) for the Cosmic Evolution Early Release Science (CEERS) survey. It is filled with galaxies. Some galaxies appear to have grown so massive, so quickly, that simulations couldn’t account for them. However, a new study finds that some of those early galaxies are in fact much less massive than they first appeared. Black holes in some of those galaxies make them appear much brighter and bigger than they really are. NASA, ESA, CSA, S. Finkelstein (University of Texas)
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Black Holes Add to Brightness
According to this latest study, the galaxies that appeared overly massive likely host black holes rapidly consuming gas. Friction in the fast-moving gas emits heat and light, making these galaxies much brighter than they would be if that light emanated just from stars. This extra light can make it appear that the galaxies contain many more stars, and hence are more massive, than we would otherwise estimate. When scientists remove these galaxies, dubbed “little red dots” (based on their red color and small size), from the analysis, the remaining early galaxies are not too massive to fit within predictions of the standard model.
“So, the bottom line is there is no crisis in terms of the standard model of cosmology,” Finkelstein said. “Any time you have a theory that has stood the test of time for so long, you have to have overwhelming evidence to really throw it out. And that’s simply not the case.”
Efficient Star Factories
Although they’ve settled the main dilemma, a less thorny problem remains: There are still roughly twice as many massive galaxies in Webb’s data of the early universe than expected from the standard model. One possible reason might be that stars formed more quickly in the early universe than they do today.
“Maybe in the early universe, galaxies were better at turning gas into stars,” Chworowsky said.
Star formation happens when hot gas cools enough to succumb to gravity and condense into one or more stars. But as the gas contracts, it heats up, generating outward pressure. In our region of the universe, the balance of these opposing forces tends to make the star formation process very slow. But perhaps, according to some theories, because the early universe was denser than today, it was harder to blow gas out during star formation, allowing the process to go faster.
More Evidence of Black Holes
Concurrently, astronomers have been analyzing the spectra of “little red dots” discovered with Webb, with researchers in both the CEERS team and others finding evidence of fast-moving hydrogen gas, a signature of black hole accretion disks. This supports the idea that at least some of the light coming from these compact, red objects comes from gas swirling around black holes, rather than stars – reinforcing Chworowsky and their team’s conclusion that they are probably not as massive as astronomers initially thought. However, further observations of these intriguing objects are incoming, and should help solve the puzzle about how much light comes from stars versus gas around black holes.
Often in science, when you answer one question, that leads to new questions. While Chworowsky and their colleagues have shown that the standard model of cosmology likely isn’t broken, their work points to the need for new ideas in star formation.
“And so there is still that sense of intrigue,” Chworowsky said. “Not everything is fully understood. That’s what makes doing this kind of science fun, because it’d be a terribly boring field if one paper figured everything out, or there were no more questions to answer.”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, Rob Gutro – rob.gutro@nasa.gov
NASA’s Goddard Space Flight Center, Greenbelt, Md.
Marc Airhart – mairhart@austin.utexas.edu
University of Texas at Austin
Christine Pulliam – cpulliam@stsci.edu
Space Telescope Science Institute, Baltimore, Md.
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Last Updated Aug 26, 2024 Editor Stephen Sabia Contact Laura Betz laura.e.betz@nasa.gov Related Terms
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By NASA
2 min read
Hubble Finds Structure in an Unstructured Galaxy
NASA, ESA, A. del Pino Molina (CEFCA), K. Gilbert and R. van der Marel (STScI), A. Cole (University of Tasmania); Image Processing: Gladys Kober (NASA/Catholic University of America) This NASA Hubble Space Telescope image features the nearby dwarf irregular galaxy Leo A, located some 2.6 million light-years away. The relatively open distribution of stars in this diminutive galaxy allows light from distant background galaxies to shine through.
Astronomers study dwarf galaxies like Leo A because they are numerous and may offer clues to how galaxies grow and evolve. Dwarf galaxies are small and dim making the most distant members of this galaxy type difficult to study. As a result, astronomers point their telescopes toward those that are relatively near to our own Milky Way galaxy, like Leo A.
Leo A is one of the most isolated galaxies in our Local Group of galaxies. Its form appears as a roughly spherical, sparsely populated mass of stars with no obvious structural features like spiral arms.
The data that created this image come from four Hubble observing programs. Three of these looked at star formation histories of relatively nearby dwarf galaxies. The fourth sought to better determine the mass of our Local Group by looking at the motions of dwarf galaxies just outside of the Local Group.
The Hubble observations that looked at star formation found distinct structural differences in the age and distribution of stars in the galaxy. Most of the younger stars are located in the middle of the galaxy, while the number of older stars increases as you move outward from the center. Hubble observations also suggest that the galaxy’s halo of stars is about one-third larger than previous estimates. This distribution suggests that star formation in Leo A occurred from the outside-in, or that older stars efficiently migrated to the outskirts of Leo A in the early stages of its evolution.
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Last Updated Aug 22, 2024 Editor Michelle Belleville Location NASA Goddard Space Flight Center Related Terms
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Since its 1990 launch, the Hubble Space Telescope has changed our fundamental understanding of the universe.
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By NASA
This view of Jupiter was captured by the JunoCam instrument aboard NASA’s Juno spacecraft during the mission’s 62nd close flyby of the giant planet on June 13. Citizen scientist Jackie Branc made the image using raw JunoCam data.Image data: NASA/JPL-Caltech/SwRI/MSSS. Image processing: Jackie Branc (CC BY) Using data from the Advanced Stellar Compass (ASC) star tracker cameras aboard NASA’s Juno, this graphic shows the mission’s model for radiation intensity at different points in the spacecraft’s orbit around Jupiter.NASA/JPL-Caltech/DTU Using cameras designed for navigation, scientists count ‘fireflies’ to determine the amount of radiation the spacecraft receives during each orbit of Jupiter.
Scientists with NASA’s Juno mission have developed the first complete 3D radiation map of the Jupiter system. Along with characterizing the intensity of the high-energy particles near the orbit of the icy moon Europa, the map shows how the radiation environment is sculpted by the smaller moons orbiting near Jupiter’s rings.
The work relies on data collected by Juno’s Advanced Stellar Compass (ASC), which was designed and built by the Technical University of Denmark, and the spacecraft’s Stellar Reference Unit (SRU), which was built by Leonardo SpA in Florence, Italy. The two datasets complement each other, helping Juno scientists characterize the radiation environment at different energies.
Both the ASC and SRU are low-light cameras designed to assist with deep-space navigation. These types of instruments are on almost all spacecraft. But to get them to operate as radiation detectors, Juno’s science team had to look at the cameras in a whole new light.
“On Juno we try to innovate new ways to use our sensors to learn about nature, and we have used many of our science instruments in ways they were not designed for,” said Scott Bolton, Juno principal investigator from the Southwest Research Institute in San Antonio. “This is the first detailed radiation map of the region at these higher energies, which is a major step in understanding how Jupiter’s radiation environment works. This will help planning observations for the next generation of missions to the Jovian system.”
Counting Fireflies
Consisting of four star cameras on the spacecraft’s magnetometer boom, Juno’s ASC takes images of stars to determine the spacecraft’s orientation in space, which is vital to the success of the mission’s magnetic field experiment. But the instrument has also proved to be a valuable detector of high-energy particle fluxes in Jupiter’s magnetosphere. The cameras record “hard radiation,” or ionizing radiation that impacts a spacecraft with sufficient energy to pass through the ASC’s shielding.
“Every quarter-second, the ASC takes an image of the stars,” said Juno scientist John Leif Jørgensen of the Technical University of Denmark. “Very energetic electrons that penetrate its shielding leave a telltale signature in our images that looks like the trail of a firefly. The instrument is programmed to count the number of these fireflies, giving us an accurate calculation of the amount of radiation.”
Jupiter’s moon Europa was captured by the JunoCam instrument aboard NASA’s Juno spacecraft during the mission’s close flyby on Sept. 29, 2022.Image data: NASA/JPL-Caltech/SwRI/MSSS. Image processing: Björn Jónsson (CC BY 3.0) Because of Juno’s ever-changing orbit, the spacecraft has traversed practically all regions of space near Jupiter.
ASC data suggests that there is more very high-energy radiation relative to lower-energy radiation near Europa’s orbit than previously thought. The data also confirms that there are more high-energy electrons on the side of Europa facing its orbital direction of motion than on the moon’s trailing side. This is because most of the electrons in Jupiter’s magnetosphere overtake Europa from behind due to the planet’s rotation, whereas the very high-energy electrons drift backward, almost like fish swimming upstream, and slam into Europa’s front side.
Jovian radiation data is not the ASC’s first scientific contribution to the mission. Even before arriving at Jupiter, ASC data was used to determine a measurement of interstellar dust impacting Juno. The imager also discovered a previously uncharted comet using the same dust-detection technique, distinguishing small bits of the spacecraft ejected by microscopic dust impacting Juno at a high velocity.
Dust Rings
Like Juno’s ASC, the SRU has been used as a radiation detector and a low-light imager. Data from both instruments indicates that, like Europa, the small “shepherd moons” that orbit within or close to the edge of Jupiter’s rings (and help to hold the shape of the rings) also appear to interact with the planet’s radiation environment. When the spacecraft flies on magnetic field lines connected to ring moons or dense dust, the radiation count on both the ASC and SRU drops precipitously. The SRU is also collecting rare low-light images of the rings from Juno’s unique vantage point.
“There is still a lot of mystery about how Jupiter’s rings were formed, and very few images have been collected by prior spacecraft,” said Heidi Becker, lead co-investigator for the SRU and a scientist at NASA’s Jet Propulsion Laboratory in Southern California, which manages the mission. “Sometimes we’re lucky and one of the small shepherd moons can be captured in the shot. These images allow us to learn more precisely where the ring moons are currently located and see the distribution of dust relative to their distance from Jupiter.”
More About the Mission
NASA’s Jet Propulsion Laboratory, a division of Caltech in Pasadena, California, manages the Juno mission for the principal investigator, Scott Bolton, of the Southwest Research Institute in San Antonio. Juno is part of NASA’s New Frontiers Program, which is managed at NASA’s Marshall Space Flight Center in Huntsville, Alabama, for the agency’s Science Mission Directorate in Washington. The Technical University of Denmark designed and built the Advanced Stellar Compass. The Stellar Reference Unit was built by Leonardo SpA in Florence, Italy. Lockheed Martin Space in Denver built and operates the spacecraft.
More information about Juno is available at:
https://www.nasa.gov/juno
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Simon Koefoed Toft
Technical University of Denmark, Copenhagen
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Southwest Research Institute, San Antonio
210-522-2254
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Last Updated Aug 20, 2024 Related Terms
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By NASA
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Warming global climate is changing the vegetation structure of forests in the far north. It’s a trend that will continue at least through the end of this century, according to NASA researchers. The change in forest structure could absorb more of the greenhouse gas carbon dioxide (CO2) from the atmosphere, or increase permafrost thawing, resulting in the release of ancient carbon. Millions of data points from the Ice, Cloud, and land Elevation Satellite 2 (ICESat-2) and Landsat missions helped inform this latest research, which will be used to refine climate forecasting computer models.
Landscape at Murphy Dome fire scar, outside of Fairbanks, Alaska, during the Arctic Boreal Vulnerability Experiment (ABoVE) in August 2022. Credit: NASA/Katie Jepson Tundra landscapes are getting taller and greener. With the warming climate, the vegetation of forests in the far north is changing as more trees and shrubs appear. These shifts in the vegetation structure of boreal forests and tundra will continue for at least the next 80 years, according to NASA scientists in a recently published study.
Boreal forests generally grow between 50 and 60 degrees north latitude, covering large parts of Alaska, Canada, Scandinavia, and Russia. The biome is home to evergreens such as pine, spruce, and fir. Farther north, the permafrost and short growing season of the tundra biome have historically made it hard to support large trees or dense forests. The vegetation in those regions has instead been made up of shrubs, mosses, and grasses.
The boundary between the two biomes is difficult to discern. Previous studies have found high-latitude plant growth increasing and moving northward into areas that earlier were sparsely covered in the shrubs and grasses of the tundra. Now, the new NASA-led study finds an increased presence of trees and shrubs in those tundra regions and adjacent transitional forests, where boreal regions and tundra meet. This is predicted to continue until at least the end of the century.
Data from the study depicted on a map of Alaska and Northern Canada highlighting the change in tree canopy cover extending into transitional landscapes. In boreal North America, the largest increases in canopy cover (dark green) have occurred in transitional tundra landscapes. These landscapes are found along the cold, northern extent of the study area and have historically supported mostly shrubs, mosses, and grasses. Credit: NASA Earth Observatory/Wanmei Liang “The results from this study advance a growing body of work that recognizes a shift in vegetation patterns within the boreal forest biome,” said Paul Montesano, lead author for the paper and research scientist at NASA Goddard’s Space Flight Center in Greenbelt, Maryland. “We’ve used satellite data to track the increased vegetation growth in this biome since 1984, and we found that it’s similar to what computer models predict for the decades to come. This paints a picture of continued change for the next 80 or so years that is particularly strong in transitional forests.”
Scientists found predictions of “positive median height changes” in all tundra landscapes and transitional – between boreal and tundra – forests featured in this study. This suggests trees and shrubs will be both larger and more abundant in areas where they are currently sparse.
“The increase of vegetation that corresponds with the shift can potentially offset some of the impact of rising CO2 emissions by absorbing more CO2 through photosynthesis,” said study co-author Chris Neigh, NASA’s Landsat 8 and 9 project scientist at Goddard. Carbon absorbed through this process would then be stored in the trees, shrubs, and soil.
The change in forest structure may also cause permafrost areas to thaw as more sunlight is absorbed by the darker colored vegetation. This could release CO2 and methane that has been stored in the soil for thousands of years.
In their paper published in Nature Communications Earth & Environment in May, NASA scientists described the mixture of satellite data, machine learning, climate variables, and climate models they used to model and predict how the forest structure will look for years to come. Specifically, they analyzed nearly 20 million data points from NASA’s ICESat-2. They then matched these data points with tens of thousands of scenes of North American boreal forests between 1984 to 2020 from Landsat, a joint mission of NASA and the U.S. Geological Survey. Advanced computing capabilities are required to create models with such large quantities of data, which are called “big data” projects.
Flight over the boreal landscapes of Fairbanks, Alaska, during the ABoVE field campaign in August 2022. Credit: NASA/Sofie Bates The ICESat-2 mission uses a laser instrument called lidar to measure the height of Earth’s surface features (like ice sheets or trees) from the vantage point of space. In the study, the authors examined these measurements of vegetation height in the far north to understand what the current boreal forest structure looks like. Scientists then modeled several future climate scenarios — adjusting to different scenarios for temperature and precipitation — to show what forest structure may look like in response.
“Our climate is changing and, as it changes, it affects almost everything in nature,” said Melanie Frost, remote sensing scientist at NASA Goddard. “It’s important for scientists to understand how things are changing and use that knowledge to inform our climate models.”
By Erica McNamee
NASA’s Goddard Space Flight Center, Greenbelt, Md.
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Last Updated Aug 06, 2024 EditorKate D. RamsayerContactErica McNameeerica.s.mcnamee@nasa.govLocationGoddard Space Flight Center Related Terms
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By NASA
Timothy Lang (ST11) is the Principal Investigator and Aaron Kaulfus (ST11) is a Co-Investigator (Co-I) on a proposal titled “Using CYGNSS with a suite of spaceborne remote sensing datasets to probe tropical maritime cold pool evolution from space”, which was recently selected for funding by NASA. CYGNSS stands for Cyclone Global Navigation Satellite System, and the proposal seeks to combine CYGNSS and other scatterometer measurements of ocean winds using machine learning to detect and track cold pools (i.e., gust front winds) from tropical maritime convection throughout their lifetimes. This work will enable a more process-oriented look at how convectively driven cold pools interact with convection and the local environment. Data from NASA precipitation sensors and NOAA geostationary observations will be included in the analysis as well. The project will last for three years, and it includes University of Alabama in Huntsville (Co-I George Priftis) as a local partner.
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