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Stellar Archaeology Traces Milky Way's History
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By European Space Agency
As the launch of the Sentinel-1C satellite approaches, we reflect on some of the many ways the Copernicus Sentinel-1 mission has given us remarkable radar insights into our planet over the years.
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By NASA
4 min read
NASA, JAXA XRISM Mission Looks Deeply Into ‘Hidden’ Stellar System
The Japan-led XRISM (X-ray Imaging and Spectroscopy Mission) observatory has captured the most detailed portrait yet of gases flowing within Cygnus X-3, one of the most studied sources in the X-ray sky.
Cygnus X-3 is a binary that pairs a rare type of high-mass star with a compact companion — likely a black hole.
Cygnus X-3 is a high-mass binary consisting of a compact object (likely a black hole) and a hot Wolf-Rayet star. This artist’s concept shows one interpretation of the system. High-resolution X-ray spectroscopy indicates two gas components: a heavy background outflow, or wind, emanating from the massive star and a turbulent structure — perhaps a wake carved into the wind — located close to the orbiting companion. As shown here, a black hole’s gravity captures some of the wind into an accretion disk around it, and the disk’s orbital motion sculpts a path (yellow arc) through the streaming gas. During strong outbursts, the companion emits jets of particles moving near the speed of light, seen here extending above and below the black hole. NASA’s Goddard Space Flight Center “The nature of the massive star is one factor that makes Cygnus X-3 so intriguing,” said Ralf Ballhausen, a postdoctoral associate at the University of Maryland, College Park, and NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “It’s a Wolf-Rayet star, a type that has evolved to the point where strong outflows called stellar winds strip gas from the star’s surface and drive it outward. The compact object sweeps up and heats some of this gas, causing it to emit X-rays.”
A paper describing the findings, led by Ballhausen, will appear in a future edition of The Astrophysical Journal.
“For XRISM, Cygnus X-3 is a Goldilocks target — its brightness is ‘just right’ in the energy range where XRISM is especially sensitive,” said co-author Timothy Kallman, an astrophysicist at NASA Goddard. “This unusual source has been studied by every X-ray satellite ever flown, so observing it is a kind of rite of passage for new X-ray missions.”
XRISM (pronounced “crism”) is led by JAXA (Japan Aerospace Exploration Agency) in collaboration with NASA, along with contributions from ESA (European Space Agency). NASA and JAXA developed the mission’s microcalorimeter spectrometer instrument, named Resolve.
Observing Cygnus X-3 for 18 hours in late March, Resolve acquired a high-resolution spectrum that allows astronomers to better understand the complex gas dynamics operating there. These include outflowing gas produced by a hot, massive star, its interaction with the compact companion, and a turbulent region that may represent a wake produced by the companion as it orbits through the outrushing gas.
XRISM’s Resolve instrument has captured the most detailed X-ray spectrum yet acquired of Cygnus X-3. Peaks indicate X-rays emitted by ionized gases, and valleys form where the gases absorb X-rays; many lines are also shifted to both higher and lower energies by gas motions. Top: The full Resolve spectrum, from 2 to 8 keV (kiloelectron volts), tracks X-rays with thousands of times the energy of visible light. Some lines are labeled with the names of the elements that produced them, such as sulfur, argon, and calcium, along with Roman numerals that refer to the number of electrons these atoms have lost. Bottom: A zoom into a region of the spectrum often dominated by features produced by transitions in the innermost electron shell (K shell) of iron atoms. These features form when the atoms interact with high-energy X-rays or electrons and respond by emitting a photon at energies between 6.4 and 7 keV. These details, clearly visible for the first time with XRISM’s Resolve instrument, will help astronomers refine their understanding of this unusual system. JAXA/NASA/XRISM Collaboration In Cygnus X-3, the star and compact object are so close they complete an orbit in just 4.8 hours. The binary is thought to lie about 32,000 light-years away in the direction of the northern constellation Cygnus.
While thick dust clouds in our galaxy’s central plane obscure any visible light from Cygnus X-3, the binary has been studied in radio, infrared, and gamma-ray light, as well as in X-rays.
The system is immersed in the star’s streaming gas, which is illuminated and ionized by X-rays from the compact companion. The gas both emits and absorbs X-rays, and many of the spectrum’s prominent peaks and valleys incorporate both aspects. Yet a simple attempt at understanding the spectrum comes up short because some of the features appear to be in the wrong place.
That’s because the rapid motion of the gas displaces these features from their normal laboratory energies due to the Doppler effect. Absorption valleys typically shift up to higher energies, indicating gas moving toward us at speeds of up to 930,000 mph (1.5 million kph). Emission peaks shift down to lower energies, indicating gas moving away from us at slower speeds.
Some spectral features displayed much stronger absorption valleys than emission peaks. The reason for this imbalance, the team concludes, is that the dynamics of the stellar wind allow the moving gas to absorb a broader range of X-ray energies emitted by the companion. The detail of the XRISM spectrum, particularly at higher energies rich in features produced by ionized iron atoms, allowed the scientists to disentangle these effects.
“A key to acquiring this detail was XRISM’s ability to monitor the system over the course of several orbits,” said Brian Williams, NASA’s project scientist for the mission at Goddard. “There’s much more to explore in this spectrum, and ultimately we hope it will help us determine if Cygnus X-3’s compact object is indeed a black hole.”
XRISM is a collaborative mission between JAXA and NASA, with participation by ESA. NASA’s contribution includes science participation from CSA (Canadian Space Agency).
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By Francis Reddy
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 Nov 25, 2024 Related Terms
Black Holes Electromagnetic Spectrum Galaxies, Stars, & Black Holes Research Goddard Space Flight Center Stars Stellar-mass Black Holes The Universe X-ray Binaries XRISM (X-Ray Imaging and Spectroscopy Mission) Facebook logo @NASAUniverse @NASAUniverse Instagram logo @NASAUniverse Keep Exploring Discover Related Topics
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By NASA
At NASA, high-end computing is essential for many agency missions. This technology helps us advance our understanding of the universe – from our planet to the farthest reaches of the cosmos. Supercomputers enable projects across diverse research, such as making discoveries about the Sun’s activity that affects technologies in space and life on Earth, building artificial intelligence-based models for innovative weather and climate science, and helping redesign the launch pad that will send astronauts to space with Artemis II.
These projects are just a sample of the many on display in NASA’s exhibit during the International Conference for High Performance Computing, Networking, Storage and Analysis, or SC24. NASA’s Dr. Nicola “Nicky” Fox, associate administrator for the agency’s Science Mission Directorate, will deliver the keynote address, “NASA’s Vision for High Impact Science and Exploration,” on Tuesday, Nov. 19, where she’ll share more about the ways NASA uses supercomputing to explore the universe for the benefit of all. Here’s a little more about the work NASA will share at the conference:
1. Simulations Help in Redesign of the Artemis Launch Environment
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This simulation of the Artemis I launch shows how the Space Launch System rocket's exhaust plumes interact with the air, water, and the launchpad. Colors on surfaces indicate pressure levels—red for high pressure and blue for low pressure. The teal contours illustrate where water is present. NASA/Chris DeGrendele, Timothy Sandstrom Researchers at NASA Ames are helping ensure astronauts launch safely on the Artemis II test flight, the first crewed mission of the Space Launch System (SLS) rocket and Orion spacecraft, scheduled for 2025. Using the Launch Ascent and Vehicle Aerodynamics software, they simulated the complex interactions between the rocket plume and the water-based sound suppression system used during the Artemis I launch, which resulted in damage to the mobile launcher platform that supported the rocket before liftoff.
Comparing simulations with and without the water systems activated revealed that the sound suppression system effectively reduces pressure waves, but exhaust gases can redirect water and cause significant pressure increases.
The simulations, run on the Aitken supercomputer at the NASA Advanced Supercomputing facility at Ames, generated about 400 terabytes of data. This data was provided to aerospace engineers at NASA’s Kennedy Space Center in Florida, who are redesigning the flame deflector and mobile launcher for the Artemis II launch.
2. Airplane Design Optimization for Fuel Efficiency
In this comparison of aircraft designs, the left wing models the aircraft’s initial geometry, while the right wing models an optimized shape. The surface is colored by the air pressure on the aircraft, with orange surfaces representing shock waves in the airflow. The optimized design modeled on the right wing reduces drag by 4% compared to the original, leading to improved fuel efficiency. NASA/Brandon Lowe To help make commercial flight more efficient and sustainable, researchers and engineers at NASA’s Ames Research Center in California’s Silicon Valley are working to refine aircraft designs to reduce air resistance, or drag, by fine-tuning the shape of wings, fuselages, and other aircraft structural components. These changes would lower the energy required for flight and reduce the amount of fuel needed, produce fewer emissions, enhance overall performance of aircraft, and could help reduce noise levels around airports.
Using NASA’s Launch, Ascent, and Vehicle Aerodynamics computational modeling software, developed at Ames, researchers are leveraging the power of agency supercomputers to run hundreds of simulations to explore a variety of design possibilities – on existing aircraft and future vehicle concepts. Their work has shown the potential to reduce drag on an existing commercial aircraft design by 4%, translating to significant fuel savings in real-world applications.
3. Applying AI to Weather and Climate
This visualization compares the track of the Category 4 hurricane, Ida, from MERRA-2 reanalysis data (left) with a prediction made without specific training, from NASA and IBM’s Prithvi WxC foundation model (right). Both models were initialized at 00 UTC on 2021-08-27.The University of Alabama in Huntsville/Ankur Kumar; NASA/Sujit Roy Traditional weather and climate models produce global and regional results by solving mathematical equations for millions of small areas (grid boxes) across Earth’s atmosphere and oceans. NASA and partners are now exploring newer approaches using artificial intelligence (AI) techniques to train a foundation model.
Foundation models are developed using large, unlabeled datasets so researchers can fine-tune results for different applications, such as creating forecasts or predicting weather patterns or climate changes, independently with minimal additional training.
NASA developed the open source, publicly available Prithvi Weather-Climate foundation model (Prithvi WxC), in collaboration with IBM Research. Prithvi WxC was pretrained using 160 variables from NASA’s Modern-era Retrospective analysis for Research and Applications (MERRA-2) dataset on the newest NVIDIA A100 GPUs at the NASA Advanced Supercomputing facility.
Armed with 2.3 billion parameters, Prithvi WxC can model a variety of weather and climate phenomena – such as hurricane tracks – at fine resolutions. Applications include targeted weather prediction and climate projection, as well as representing physical processes like gravity waves.
4. Simulations and AI Reveal the Fascinating World of Neutron Stars
3D simulation of pulsar magnetospheres, run on NASA’s Aitken supercomputer using data from the agency‘s Fermi space telescope. The red arrow shows the direction of the star’s magnetic field. Blue lines trace high-energy particles, producing gamma rays, in yellow. Green lines represent light particles hitting the observer’s plane, illustrating how Fermi detects pulsar gamma rays. NASA/Constantinos Kalapotharakos To explore the extreme conditions inside neutron stars, researchers at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, are using a blend of simulation, observation, and AI to unravel the mysteries of these extraordinary cosmic objects. Neutron stars are the dead cores of stars that have exploded and represent some of the densest objects in the universe.
Cutting-edge simulations, run on supercomputers at the NASA Advanced Supercomputing facility, help explain phenomena observed by NASA’s Fermi Gamma-ray Space Telescope and Neutron star Interior Composition Explorer (NICER) observatory. These phenomena include the rapidly spinning, highly magnetized neutron stars known as pulsars, whose detailed physical mechanisms have remained mysterious since their discovery. By applying AI tools such as deep neural networks, the scientists can infer the stars’ mass, radius, magnetic field structure, and other properties from data obtained by the NICER and Fermi observatories.
The simulations’ unprecedented results will guide similar studies of black holes and other space environments, as well as play a pivotal role in shaping future scientific space missions and mission concepts.
5. Modeling the Sun in Action – From Tiny to Large Scales
Image from a 3D simulation showing the evolution of flows in the upper layers of the Sun, with the most vigorous motions shown in red. These turbulent flows can generate magnetic fields and excite sound waves, shock waves, and eruptions. NASA/Irina Kitiashvili and Timothy A. Sandstrom The Sun’s activity, producing events such as solar flares and coronal mass ejections, influences the space environment and cause space weather disturbances that can interfere with satellite electronics, radio communications, GPS signals, and power grids on Earth. Scientists at NASA Ames produced highly realistic 3D models that – for the first time – allow them to examine the physics of solar plasma in action, from very small to very large scales. These models help interpret observations from NASA spacecraft like the Solar Dynamics Observatory (SDO).
Using NASA’s StellarBox code on supercomputers at NASA’s Advanced Supercomputing facility, the scientists improved our understanding of the origins of solar jets and tornadoes – bursts of extremely hot, charged plasma in the solar atmosphere. These models allow the science community to address long-standing questions of solar magnetic activity and how it affects space weather.
6. Scientific Visualization Makes NASA Data Understandable
This global map is a frame from an animation showing how wind patterns and atmospheric circulation moved carbon dioxide through Earth’s atmosphere from January to March 2020. The DYAMOND model’s high resolution shows unique sources of carbon dioxide emissions and how they spread across continents and oceans.NASA/Scientific Visualization Studio NASA simulations and observations can yield petabytes of data that are difficult to comprehend in their original form. The Scientific Visualization Studio (SVS), based at NASA Goddard, turns data into insight by collaborating closely with scientists to create cinematic, high-fidelity visualizations.
Key infrastructure for these SVS creations includes the NASA Center for Climate Simulation’s Discover supercomputer at Goddard, which hosts a variety of simulations and provides data analysis and image-rendering capabilities. Recent data-driven visualizations show a coronal mass ejection from the Sun hitting Earth’s magnetosphere using the Multiscale Atmosphere-Geospace Environment (MAGE) model; global carbon dioxide emissions circling the planet in the DYnamics of the Atmospheric general circulation Modeled On Non-hydrostatic Domains (DYAMOND) model; and representations of La Niña and El Niño weather patterns using the El Niño-Southern Oscillation (ENSO) model.
For more information about NASA’s virtual exhibit at the International Conference for High Performance Computing, Networking, Storage and Analysis, being held in Atlanta, Nov. 17-22, 2024, visit:
https://www.nas.nasa.gov/SC24
For more information about supercomputers run by NASA High-End Computing, visit:
https://hec.nasa.gov
For news media:
Members of the news media interested in covering this topic should reach out to the NASA Ames newsroom.
Authors: Jill Dunbar, Michelle Moyer, and Katie Pitta, NASA’s Ames Research Center; and Jarrett Cohen, NASA’s Goddard Space Flight Center
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By NASA
Hubble Space Telescope Home NASA’s Hubble Sees… Hubble Space Telescope Hubble Home Overview About Hubble The History of Hubble Hubble Timeline Why Have a Telescope in Space? Hubble by the Numbers At the Museum FAQs Impact & Benefits Hubble’s Impact & Benefits Science Impacts Cultural Impact Technology Benefits Impact on Human Spaceflight Astro Community Impacts Science Hubble Science Science Themes Science Highlights Science Behind Discoveries Hubble’s Partners in Science Universe Uncovered Explore the Night Sky Observatory Hubble Observatory Hubble Design Mission Operations Missions to Hubble Hubble vs Webb Team Hubble Team Career Aspirations Hubble Astronauts News Hubble News Hubble News Archive Social Media Media Resources Multimedia Multimedia Images Videos Sonifications Podcasts E-books Lithographs Fact Sheets Glossary Posters Hubble on the NASA App More Online Activities 5 Min Read NASA’s Hubble Sees Aftermath of Galaxy’s Scrape with Milky Way
This artist’s concept shows a closeup of the Large Magellanic Cloud, a dwarf galaxy that is one of the Milky Way galaxy’s nearest neighbors. Credits:
NASA, ESA, Ralf Crawford (STScI) A story of survival is unfolding at the outer reaches of our galaxy, and NASA’s Hubble Space Telescope is witnessing the saga.
The Large Magellanic Cloud, also called the LMC, is one of the Milky Way galaxy’s nearest neighbors. This dwarf galaxy looms large on the southern nighttime sky at 20 times the apparent diameter of the full Moon.
Many researchers theorize that the LMC is not in orbit around our galaxy, but is just passing by. These scientists think that the LMC has just completed its closest approach to the much more massive Milky Way. This passage has blown away most of the spherical halo of gas that surrounds the LMC.
Now, for the first time, astronomers been able to measure the size of the LMC’s halo – something they could do only with Hubble. In a new study to be published in The Astrophysical Journal Letters, researchers were surprised to find that it is so extremely small, about 50,000 light-years across. That’s around 10 times smaller than halos of other galaxies that are the LMC’s mass. Its compactness tells the story of its encounter with the Milky Way.
“The LMC is a survivor,” said Andrew Fox of AURA/STScI for the European Space Agency in Baltimore, who was principal investigator on the observations. “Even though it’s lost a lot of its gas, it’s got enough left to keep forming new stars. So new star-forming regions can still be created. A smaller galaxy wouldn’t have lasted – there would be no gas left, just a collection of aging red stars.”
This artist’s concept shows the Large Magellanic Cloud, or LMC, in the foreground as it passes through the gaseous halo of the much more massive Milky Way galaxy. The encounter has blown away most of the spherical halo of gas that surrounds the LMC, as illustrated by the trailing gas stream reminiscent of a comet’s tail. Still, a compact halo remains, and scientists do not expect this residual halo to be lost. The team surveyed the halo by using the background light of 28 quasars, an exceptionally bright type of active galactic nucleus that shines across the universe like a lighthouse beacon. Their light allows scientists to “see” the intervening halo gas indirectly through the absorption of the background light. The lines represent the Hubble Space Telescope’s view from its orbit around Earth to the distant quasars through the LMC’s gas. NASA, ESA, Ralf Crawford (STScI)
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Though quite a bit worse for wear, the LMC still retains a compact, stubby halo of gas – something that it wouldn’t have been able to hold onto gravitationally had it been less massive. The LMC is 10 percent the mass of the Milky Way, making it heftier than most dwarf galaxies.
“Because of the Milky Way’s own giant halo, the LMC’s gas is getting truncated, or quenched,” explained STScI’s Sapna Mishra, the lead author on the paper chronicling this discovery. “But even with this catastrophic interaction with the Milky Way, the LMC is able to retain 10 percent of its halo because of its high mass.”
A Gigantic Hair Dryer
Most of the LMC’s halo was blown away due to a phenomenon called ram-pressure stripping. The dense environment of the Milky Way pushes back against the incoming LMC and creates a wake of gas trailing the dwarf galaxy – like the tail of a comet.
“I like to think of the Milky Way as this giant hairdryer, and it’s blowing gas off the LMC as it comes into us,” said Fox. “The Milky Way is pushing back so forcefully that the ram pressure has stripped off most of the original mass of the LMC’s halo. There’s only a little bit left, and it’s this small, compact leftover that we’re seeing now.”
As the ram pressure pushes away much of the LMC’s halo, the gas slows down and eventually will rain into the Milky Way. But because the LMC has just gotten past its closest approach to the Milky Way and is moving outward into deep space again, scientists do not expect the whole halo will be lost.
Only with Hubble
To conduct this study, the research team analyzed ultraviolet observations from the Mikulski Archive for Space Telescopes at STScI. Most ultraviolet light is blocked by the Earth’s atmosphere, so it cannot be observed with ground-based telescopes. Hubble is the only current space telescope tuned to detect these wavelengths of light, so this study was only possible with Hubble.
The team surveyed the halo by using the background light of 28 bright quasars. The brightest type of active galactic nucleus, quasars are believed to be powered by supermassive black holes. Shining like lighthouse beacons, they allow scientists to “see” the intervening halo gas indirectly through the absorption of the background light. Quasars reside throughout the universe at extreme distances from our galaxy.
This artist’s concept illustrates the Large Magellanic Cloud’s (LMC’s) encounter with the Milky Way galaxy’s gaseous halo. In the top panel, at the middle of the right side, the LMC begins crashing through our galaxy’s much more massive halo. The bright purple bow shock represents the leading edge of the LMC’s halo, which is being compressed as the Milky Way’s halo pushes back against the incoming LMC. In the middle panel, part of the halo is being stripped and blown back into a streaming tail of gas that eventually will rain into the Milky Way. The bottom panel shows the progression of this interaction, as the LMC’s comet-like tail becomes more defined. A compact LMC halo remains. Because the LMC is just past its closest approach to the Milky Way and is moving outward into deep space again, scientists do not expect the residual halo will be lost. NASA, ESA, Ralf Crawford (STScI)
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The scientists used data from Hubble’s Cosmic Origins Spectrograph (COS) to detect the presence of the halo’s gas by the way it absorbs certain colors of light from background quasars. A spectrograph breaks light into its component wavelengths to reveal clues to the object’s state, temperature, speed, quantity, distance, and composition. With COS, they measured the velocity of the gas around the LMC, which allowed them to determine the size of the halo.
Because of its mass and proximity to the Milky Way, the LMC is a unique astrophysics laboratory. Seeing the LMC’s interplay with our galaxy helps scientists understand what happened in the early universe, when galaxies were closer together. It also shows just how messy and complicated the process of galaxy interaction is.
Looking to the Future
The team will next study the front side of the LMC’s halo, an area that has not yet been explored.
“In this new program, we are going to probe five sightlines in the region where the LMC’s halo and the Milky Way’s halo are colliding,” said co-author Scott Lucchini of the Center for Astrophysics | Harvard & Smithsonian. “This is the location where the halos are compressed, like two balloons pushing against each other.”
The Hubble Space Telescope has been operating for over three decades and continues to make ground-breaking discoveries that shape our fundamental understanding of the universe. Hubble is a project of international cooperation between NASA and ESA (European Space Agency). NASA’s Goddard Space Flight Center in Greenbelt, Maryland, manages the telescope and mission operations. Lockheed Martin Space, based in Denver, Colorado, also supports mission operations at Goddard. The Space Telescope Science Institute in Baltimore, Maryland, which is operated by the Association of Universities for Research in Astronomy, conducts Hubble science operations for NASA.
Facebook logo @NASAHubble @NASAHubble Instagram logo @NASAHubble Media Contacts:
Claire Andreoli (claire.andreoli@nasa.gov)
NASA’s Goddard Space Flight Center, Greenbelt, MD
Ann Jenkins, Ray Villard
Space Telescope Science Institute, Baltimore, MD
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Last Updated Nov 14, 2024 Editor Andrea Gianopoulos Location NASA Goddard Space Flight Center Related Terms
Astrophysics Astrophysics Division Galaxies Hubble Space Telescope Irregular Galaxies Spiral Galaxies The Milky Way Keep Exploring Discover More Topics From NASA
Hubble Space Telescope
Since its 1990 launch, the Hubble Space Telescope has changed our fundamental understanding of the universe.
Galaxy Details and Mergers
Hubble’s Galaxies
Explore the Night Sky
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