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Cosmic Collisions - European HST Scientists Catch Merging Galaxies in the Act
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By NASA
5 min read
NASA’s NICER Maps Debris From Recurring Cosmic Crashes
Lee esta nota de prensa en español aquí.
For the first time, astronomers have probed the physical environment of repeating X-ray outbursts near monster black holes thanks to data from NASA’s NICER (Neutron star Interior Composition Explorer) and other missions.
Scientists have only recently encountered this class of X-ray flares, called QPEs, or quasi-periodic eruptions. A system astronomers have nicknamed Ansky is the eighth QPE source discovered, and it produces the most energetic outbursts seen to date. Ansky also sets records in terms of timing and duration, with eruptions every 4.5 days or so that last approximately 1.5 days.
“These QPEs are mysterious and intensely interesting phenomena,” said Joheen Chakraborty, a graduate student at the Massachusetts Institute of Technology in Cambridge. “One of the most intriguing aspects is their quasi-periodic nature. We’re still developing the methodologies and frameworks we need to understand what causes QPEs, and Ansky’s unusual properties are helping us improve those tools.”
Watch how astronomers used data from NASA’s NICER (Neutron star Interior Composition Explorer) to study a mysterious cosmic phenomenon called a quasi-periodic eruption, or QPE.
NASA’s Goddard Space Flight Center Ansky’s name comes from ZTF19acnskyy, the moniker of a visible-light outburst seen in 2019. It was located in a galaxy about 300 million light-years away in the constellation Virgo. This event was the first indication that something unusual might be happening.
A paper about Ansky, led by Chakraborty, was published Tuesday in The Astrophysical Journal.
A leading theory suggests that QPEs occur in systems where a relatively low-mass object passes through the disk of gas surrounding a supermassive black hole that holds hundreds of thousands to billions of times the Sun’s mass.
When the lower-mass object punches through the disk, its passage drives out expanding clouds of hot gas that we observe as QPEs in X-rays.
Scientists think the eruptions’ quasi-periodicity occurs because the smaller object’s orbit is not perfectly circular and spirals toward the black hole over time. Also, the extreme gravity close to the black hole warps the fabric of space-time, altering the object’s orbits so they don’t close on themselves with each cycle. Scientists’ current understanding suggests the eruptions repeat until the disk disappears or the orbiting object disintegrates, which may take up to a few years.
A system astronomers call Ansky, in the galaxy at the center of this image, is home to a recently discovered series of quasi-periodic eruptions. Sloan Digital Sky Survey “Ansky’s extreme properties may be due to the nature of the disk around its supermassive black hole,” said Lorena Hernández-García, an astrophysicist at the Millennium Nucleus on Transversal Research and Technology to Explore Supermassive Black Holes, the Millennium Institute of Astrophysics, and University of Valparaíso in Chile. “In most QPE systems the supermassive black hole likely shreds a passing star, creating a small disk very close to itself. In Ansky’s case, we think the disk is much larger and can involve objects farther away, creating the longer timescales we observe.”
Hernández-García, in addition to being a co-author on Chakraborty’s paper, led the study that discovered Ansky’s QPEs, which was published in April in Nature Astronomy and used data from NICER, NASA’s Neil Gehrels Swift Observatory and Chandra X-ray Observatory, as well as ESA’s (European Space Agency’s) XMM-Newton space telescope.
NICER’s position on the International Space Station allowed it to observe Ansky about 16 times every day from May to July 2024. The frequency of the observations was critical in detecting the X-ray fluctuations that revealed Ansky produces QPEs.
Chakraborty’s team used data from NICER and XMM-Newton to map the rapid evolution of the ejected material driving the observed QPEs in unprecedented detail by studying variations in X-ray intensity during the rise and fall of each eruption.
The researchers found that each impact resulted in about a Jupiter’s worth of mass reaching expansion velocities around 15% of the speed of light.
The NICER (Neutron star Interior Composition Explorer) X-ray telescope is reflected on NASA astronaut and Expedition 72 flight engineer Nick Hague’s spacesuit helmet visor in this high-flying “space-selfie” taken during a spacewalk on Jan. 16, 2025. NASA/Nick Hague The NICER telescope’s ability to frequently observe Ansky from the space station and its unique measurement capabilities also made it possible for the team to measure the size and temperature of the roughly spherical bubble of debris as it expanded.
“All NICER’s Ansky observations used in these papers were collected after the instrument experienced a ‘light leak’ in May 2023,” said Zaven Arzoumanian, the mission’s science lead at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “Even though the leak – which was patched in January – affected the telescope’s observing strategy, NICER was still able to make vital contributions to time domain astronomy, or the study of changes in the cosmos on timescales we can see.”
After the repair, NICER continued observing Ansky to explore how the outbursts have evolved over time. A paper about these results, led by Hernández-García and co-authored by Chakraborty, is under review.
Observational studies of QPEs like Chakraborty’s will also play a key role in preparing the science community for a new era of multimessenger astronomy, which combines measurements using light, elementary particles, and space-time ripples called gravitational waves to better understand objects and events in the universe.
One goal of ESA’s future LISA (Laser Interferometer Space Antenna) mission, in which NASA is a partner, is to study extreme mass-ratio inspirals — or systems where a low-mass object orbits a much more massive one, like Ansky. These systems should emit gravitational waves that are not observable with current facilities. Electromagnetic studies of QPEs will help improve models of those systems ahead of LISA’s anticipated launch in the mid-2030s.
“We’re going to keep observing Ansky for as long as we can,” Chakraborty said. “We’re still in the infancy of understanding QPEs. It’s such an exciting time because there’s so much to learn.”
Download images and videos through NASA’s Scientific Visualization Studio.
By Jeanette Kazmierczak
NASA’s Goddard Space Flight Center, Greenbelt, Md.
Media Contact:
Claire Andreoli
301-286-1940
claire.andreoli@nasa.gov
NASA’s Goddard Space Flight Center, Greenbelt, Md.
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Last Updated May 06, 2025 Editor Jeanette Kazmierczak Location Goddard Space Flight Center Related Terms
The Universe Astrophysics Black Holes Galaxies, Stars, & Black Holes Galaxies, Stars, & Black Holes Research International Space Station (ISS) ISS Research NICER (Neutron star Interior Composition Explorer) Science & Research Supermassive Black Holes X-ray Astronomy View the full article
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By NASA
Explore This Section Projects Highlights Publications NASA Citizen Scientists Science Activation Resources 2 min read
Amateur Radio Scientists Shine at the 2025 HamSCI Workshop
A collage of Posters from HamSCI’s March workshop. You can read them all online! Love Ham Radio? The HamSCI project fosters collaboration between amateur radio operators and professional researchers. Its goals are to advance scientific research and understanding through amateur radio activities, encourage the development of modern technologies to support this research, and provide educational opportunities for the amateur community and the public.
HamSCI held its annual Workshop, ‘HamSCI’s Big Year’, at the New Jersey Institute of Technology in late March. Over 100 members of the HamSCI community attended: researchers, students (secondary through graduate level), and citizen scientist volunteers. Over the two-day event, in-person and virtual participants experienced twenty-five talks on topics ranging from analysis of HamSCI’s 2023/24 Festivals of Eclipse Ionospheric Science events to space weather observations made during the May 10, 2024 geomagnetic superstorm.
The Workshop hosted a variety of Keynote and Invited Tutorial speakers, including distinguished scientists and leaders in the Amateur (ham) Radio community. The Workshop concluded with a poster session, featuring current research, ongoing educational activities, and concepts for future events involving Sun-space-Earth science topics. Posters were submitted from the US, Brazil, Egypt, the United Kingdom, and Turkey.
Explore the workshop presentations and posters. Videos of conference presentations will be available at the HamSCI website in a few months.
HamSCI is supported by NASA, the National Science Foundation, and the Amateur Radio Digital Communications (ARDC) foundation.
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Last Updated May 01, 2025 Related Terms
Citizen Science Get Involved Heliophysics Explore More
8 min read How to Contribute to Citizen Science with NASA
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By NASA
3 min read
Help Classify Galaxies Seen by NASA’s James Webb Space Telescope!
The Galaxy Zoo classification interface shows you an image from NASA’s Webb telescope and asks you questions about it. Image credit: Galaxy Zoo, Zooniverse. Inset galaxy: NASA/STScI/CEERS/TACC/S. Finkelstein/M. Bagley/Z. Levay/A. Pagan NASA needs your help identifying the shapes of thousands of galaxies in images taken by our James Webb Space Telescope with the Galaxy Zoo project. These classifications will help scientists answer questions about how the shapes of galaxies have changed over time, what caused these changes, and why. Thanks to the light collecting power of Webb, there are now over 500,000 images of galaxies on website of the Galaxy Zoo citizen science project—more images than scientists can classify by themselves.
“This is a great opportunity to see images from the newest space telescope,” said volunteer Christine Macmillan from Aberdeen, Scotland. “Galaxies at the edge of our universe are being seen for the first time, just as they are starting to form. Just sign up and answer simple questions about the shape of the galaxy that you are seeing. Anyone can do it, ages 10 and up!”
As we look at more distant objects in the universe, we see them as they were billions of years ago because light takes time to travel to us. With Webb, we can spot galaxies at greater distances than ever before. We’re seeing what some of the earliest galaxies ever detected look like, for the first time. The shapes of these galaxies tell us about how they were born, how and when they formed stars, and how they interacted with their neighbors. By looking at how more distant galaxies have different shapes than close galaxies, we can work out which processes were more common at different times in the universe’s history.
At Galaxy Zoo, you’ll first examine an image from the Webb telescope. Then you will be asked several questions, such as ‘Is the galaxy round?’, or ‘Are there signs of spiral arms?’. If you’re quick, you may even be the first person to see the galaxies you’re asked to classify.
“I’m amazed and honored to be one of the first people to actually see these images! What a privilege!” said volunteer Elisabeth Baeten from Leuven, Belgium.
Galaxy Zoo is a citizen science project with a long history of scientific impact. Galaxy Zoo volunteers have been exploring deep space since July 2007, starting with a million galaxies from a telescope in New Mexico called the Sloan Digital Sky Survey and then, moving on to images from space telescopes like NASA’s Hubble Space Telescope and ESA (European Space Agency)’s Euclid telescope. The project has revealed spectacular mergers, taught us about how the black holes at the center of galaxies affect their hosts, and provided insight into how features like spiral arms form and grow.
Now, in addition to adding new data from Webb, the science team has incorporated an AI algorithm called ZooBot, which will sift through the images first and label the ‘easier ones’ where there are many examples that already exist in previous images from the Hubble Space Telescope. When ZooBot is not confident on the classification of a galaxy, perhaps due to complex or faint structures, it will show it to users on Galaxy Zoo to get their human classifications, which will then help ZooBot learn more. Working together, humans and AI can accurately classify limitless numbers of galaxies. The Galaxy Zoo science team acknowledges support from the International Space Sciences Institute (ISSI), who provided funding for the team to get together and work on Galaxy Zoo. Join the project now.
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Last Updated Apr 29, 2025 Related Terms
Astrophysics Division Citizen Science Get Involved James Webb Space Telescope (JWST) Explore More
2 min read Hubble Visits Glittering Cluster, Capturing Its Ultraviolet Light
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By European Space Agency
A new wave of ocean scientists has embarked on an extraordinary six-week voyage aboard a majestic tall ship that set sail today from Norway bound for southern France. But this is no ordinary journey.
Thanks to this ESA Advanced Ocean Training Course, these upcoming researchers will be taking a deep dive into ocean science, empowering them with skills to harness satellite data for research, innovation and sustainable development – and preparing them to become tomorrow’s leaders and ambassadors for ocean science.
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By NASA
ESA/Hubble & NASA, K. Noll This newly reprocessed image released on April 18, 2025, provides a new view of an enormous, 9.5-light-year-tall pillar of cold gas and dust. Despite its size, it’s just one small piece of the greater Eagle Nebula, also called Messier 16.
The Eagle Nebula is one of many nebulae in the Milky Way that are known for their sculpted, dusty clouds. Nebulae take on these fantastic shapes when exposed to powerful radiation and winds from infant stars. Regions with denser gas are more able to withstand the onslaught of radiation and stellar winds from young stars, and these dense areas remain as dusty sculptures like the starry pillar shown here.
Download this image.
Image credit: ESA/Hubble & NASA, K. Noll
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