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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
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By NASA
This photo shows the Optical Telescope Assembly for NASA’s Nancy Grace Roman Space Telescope, which was recently delivered to the largest clean room at the agency’s Goddard Space Flight Center in Greenbelt, Md.NASA/Chris Gunn NASA’s Nancy Grace Roman Space Telescope is one giant step closer to unlocking the mysteries of the universe. The mission has now received its final major delivery: the Optical Telescope Assembly, which includes a 7.9-foot (2.4-meter) primary mirror, nine additional mirrors, and supporting structures and electronics. The assembly was delivered Nov. 7. to the largest clean room at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, where the observatory is being built.
The telescope will focus cosmic light and send it to Roman’s instruments, revealing many billions of objects strewn throughout space and time. Using the mission’s Wide Field Instrument, a 300-megapixel infrared camera, astronomers will survey the cosmos all the way from the outskirts of our solar system toward the edge of the observable universe. Scientists will use Roman’s Coronagraph Instrument to test new technologies for dimming host stars to image planets and dusty disks around them in far better detail than ever before.
“We have a top-notch telescope that’s well aligned and has great optical performance at the cold temperatures it will see in space,” said Bente Eegholm, optics lead for Roman’s Optical Telescope Assembly at NASA Goddard. “I am now looking forward to the next phase where the telescope and instruments will be put together to form the Roman observatory.”
In this photo, optical engineer Bente Eegholm inspects the surface of the primary mirror for NASA’s Nancy Grace Roman Space Telescope. This 7.9-foot (2.4-meter) mirror is a major component of the Optical Telescope Assembly, which also contains nine additional mirrors and supporting structures and electronics.NASA/Chris Gunn Designed and built by L3Harris Technologies in Rochester, New York, the assembly incorporates key optics (including the primary mirror) that were made available to NASA by the National Reconnaissance Office. The team at L3Harris then reshaped the mirror and built upon the inherited hardware to ensure it would meet Roman’s specifications for expansive, sensitive infrared observations.
“The telescope will be the foundation of all of the science Roman will do, so its design and performance are among the largest factors in the mission’s survey capability,” said Josh Abel, lead Optical Telescope Assembly systems engineer at NASA Goddard.
The team at Goddard worked closely with L3Harris to ensure these stringent requirements were met and that the telescope assembly will integrate smoothly into the rest of the Roman observatory.
The assembly’s design and performance will largely determine the quality of the mission’s results, so the manufacturing and testing processes were extremely rigorous. Each optical component was tested individually prior to being assembled and assessed together earlier this year. The tests helped ensure that the alignment of the telescope’s mirrors will change as expected when the telescope reaches its operating temperature in space.
Then, the telescope was put through tests simulating the extreme shaking and intense sound waves associated with launch. Engineers also made sure that tiny components called actuators, which will adjust some of the mirrors in space, move as predicted. And the team measured gases released from the assembly as it transitioned from normal air pressure to a vacuum –– the same phenomenon that has led astronauts to report that space smells gunpowdery or metallic. If not carefully controlled, these gases could contaminate the telescope or instruments.
Upon arrival at NASA’s Goddard Space Flight Center, the Optical Telescope Assembly for the agency’s Nancy Grace Roman Space Telescope was lifted out of the shipping fixture and placed with other mission hardware in Goddard’s largest clean room. Now, it will be installed onto Roman’s Instrument Carrier, a structure that will keep the telescope and Roman’s two instruments optically aligned. The assembly’s electronics box –– essentially the telescope’s brain –– will be mounted within the spacecraft along with Roman’s other electronics.NASA/Chris Gunn Finally, the telescope underwent a month-long thermal vacuum test to ensure it will withstand the temperature and pressure environment of space. The team closely monitored it during cold operating conditions to ensure the telescope’s temperature will remain constant to within a fraction of a degree. Holding the temperature constant allows the telescope to remain in stable focus, making Roman’s high-resolution images consistently sharp. Nearly 100 heaters on the telescope will help keep all parts of it at a very stable temperature.
“It is very difficult to design and build a system to hold temperatures to such a tight stability, and the telescope performed exceptionally,” said Christine Cottingham, thermal lead for Roman’s Optical Telescope Assembly at NASA Goddard.
Now that the assembly has arrived at Goddard, it will be installed onto Roman’s Instrument Carrier, a structure that will keep the telescope and Roman’s two instruments optically aligned. The assembly’s electronics box –– essentially the telescope’s brain –– will be mounted within the spacecraft along with Roman’s other electronics.
With this milestone, Roman remains on track for launch by May 2027.
“Congratulations to the team on this stellar accomplishment!” said J. Scott Smith, the assembly’s telescope manager at NASA Goddard. “The completion of the telescope marks the end of an epoch and incredible journey for this team, and yet only a chapter in building Roman. The team’s efforts have advanced technology and ignited the imaginations of those who dream of exploring the stars.”
Virtually tour an interactive version of the telescope The Nancy Grace Roman Space Telescope is managed at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, with participation by NASA’s Jet Propulsion Laboratory and Caltech/IPAC in Southern California, the Space Telescope Science Institute in Baltimore, and a science team comprising scientists from various research institutions. The primary industrial partners are BAE Systems Inc. in Boulder, Colorado; L3Harris Technologies in Rochester, New York; and Teledyne Scientific & Imaging in Thousand Oaks, California.
By Ashley Balzer
NASA’s Goddard Space Flight Center, Greenbelt, Md.
Media Contact:
Claire Andreoli
NASA’s Goddard Space Flight Center, Greenbelt, Md.
claire.andreoli@nasa.gov
301-286-1940
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Last Updated Nov 14, 2024 EditorAshley BalzerContactAshley Balzerashley.m.balzer@nasa.govLocationGoddard Space Flight Center Related Terms
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By NASA
1 min read
Preparations for Next Moonwalk Simulations Underway (and Underwater)
Shauntina Lilly, a NASA Glenn public affairs officer, speaks to students about NASA’s available internships and educational resources during the STEM Goes Red for Girls event at Great Lakes Science Center, home of the NASA Glenn Visitor Center, on Oct. 21.Credit: NASA/Debbie Welch NASA’s Glenn Research Center in Cleveland supported this year’s STEM Goes Red for Girls event at Great Lakes Science Center on Oct. 21. The program provides seventh and eighth grade students exposure to some of Greater Cleveland’s leading STEM companies. The event also featured a hands-on exhibitor fair, speed mentoring, and educational classes.
Hosted by the American Heart Association, this year’s event welcomed its largest audience to date with 352 students and educators from 32 schools within Northeast Ohio. NASA Glenn’s presence focused heavily on internships and career advice, but also highlighted the center’s work with the Space Communications and Navigation program’s Deep Space Network. Glenn’s Julie Sufka also served as a mentor, speaking to young girls about STEM opportunities in mathematics.
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By NASA
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Preparations for Next Moonwalk Simulations Underway (and Underwater)
The American Institute of Aeronautics and Astronautics (AIAA) has named two distinguished engineers at NASA’s Glenn Research Center in Cleveland AIAA Associate Fellows.
The grade of Associate Fellow recognizes individuals who have accomplished or overseen important engineering or scientific work, done original work of outstanding merit, or have otherwise made outstanding contributions to the arts, sciences, or technology of aeronautics or astronautics. To be selected as an Associate Fellow, an individual must be an AIAA Senior Member in good standing, with at least 12 years of professional experience, and be recommended by three AIAA members.
L. Danielle KochCredit: NASA L. Danielle Koch, aerospace engineer, performs research and educational outreach at NASA Glenn. Her 34-year career at NASA has been dedicated to conducting research for safer, cleaner, and quieter aircraft engines; high-performance ventilation systems for spacecraft; and bio-inspired broadband acoustic absorbers. She has authored over 50 technical publications and has been granted three patents. Koch has been recognized for excellence in engineering and educational outreach with many awards, most recently named as one of the 2024 Women of Distinction by the Girl Scouts of Northeast Ohio.
Dr. Sam LeeCredit: NASA Dr. Sam Lee, a research engineer supporting the Aircraft Icing Branch, conducts research in NASA Glenn’s Icing Research Tunnel to study how ice builds up, or accretes, on aircraft surfaces. The results from the experiments are used to understand the physics of how ice accretes on aircraft during flight and to provide the validation data to develop computational tools to predict ice accretion. He also performs research on the effects of ice accretion on aircraft performance in aerodynamic wind tunnels. Lee has authored 17 conference papers and journal papers. He has contributed to the development of many future engineers and scientists as a mentor for NASA’s Explorer Scouts program and various college internship programs. Lee has been part of the Aircraft Icing Branch since 2002.
AIAA will formally honor and induct the class at the AIAA Associate Fellows Induction Ceremony and Dinner on Jan. 8, 2025, during the 2025 AIAA SciTech Forum in Orlando.
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By NASA
4 min read
NASA’s Swift Studies Gas-Churning Monster Black Holes
A pair of monster black holes swirl in a cloud of gas in this artist’s concept of AT 2021hdr, a recurring outburst studied by NASA’s Neil Gehrels Swift Observatory and the Zwicky Transient Facility at Palomar Observatory in California. NASA/Aurore Simonnet (Sonoma State University) Scientists using observations from NASA’s Neil Gehrels Swift Observatory have discovered, for the first time, the signal from a pair of monster black holes disrupting a cloud of gas in the center of a galaxy.
“It’s a very weird event, called AT 2021hdr, that keeps recurring every few months,” said Lorena Hernández-García, an astrophysicist at the Millennium Institute of Astrophysics, the Millennium Nucleus on Transversal Research and Technology to Explore Supermassive Black Holes, and University of Valparaíso in Chile. “We think that a gas cloud engulfed the black holes. As they orbit each other, the black holes interact with the cloud, perturbing and consuming its gas. This produces an oscillating pattern in the light from the system.”
A paper about AT 2021hdr, led by Hernández-García, was published Nov. 13 in the journal Astronomy and Astrophysics.
The dual black holes are in the center of a galaxy called 2MASX J21240027+3409114, located 1 billion light-years away in the northern constellation Cygnus. The pair are about 16 billion miles (26 billion kilometers) apart, close enough that light only takes a day to travel between them. Together they contain 40 million times the Sun’s mass.
Scientists estimate the black holes complete an orbit every 130 days and will collide and merge in approximately 70,000 years.
AT 2021hdr was first spotted in March 2021 by the Caltech-led ZTF (Zwicky Transient Facility) at the Palomar Observatory in California. It was flagged as a potentially interesting source by ALeRCE (Automatic Learning for the Rapid Classification of Events). This multidisciplinary team combines artificial intelligence tools with human expertise to report events in the night sky to the astronomical community using the mountains of data collected by survey programs like ZTF.
“Although this flare was originally thought to be a supernova, outbursts in 2022 made us think of other explanations,” said co-author Alejandra Muñoz-Arancibia, an ALeRCE team member and astrophysicist at the Millennium Institute of Astrophysics and the Center for Mathematical Modeling at the University of Chile. “Each subsequent event has helped us refine our model of what’s going on in the system.”
Since the first flare, ZTF has detected outbursts from AT 2021hdr every 60 to 90 days.
Hernández-García and her team have been observing the source with Swift since November 2022. Swift helped them determine that the binary produces oscillations in ultraviolet and X-ray light on the same time scales as ZTF sees them in the visible range.
The researchers conducted a Goldilocks-type elimination of different models to explain what they saw in the data.
Initially, they thought the signal could be the byproduct of normal activity in the galactic center. Then they considered whether a tidal disruption event — the destruction of a star that wandered too close to one of the black holes — could be the cause.
Finally, they settled on another possibility, the tidal disruption of a gas cloud, one that was bigger than the binary itself. When the cloud encountered the black holes, gravity ripped it apart, forming filaments around the pair, and friction started to heat it. The gas got particularly dense and hot close to the black holes. As the binary orbits, the complex interplay of forces ejects some of the gas from the system on each rotation. These interactions produce the fluctuating light Swift and ZTF observe.
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Watch as a gas cloud encounters two supermassive black holes in this simulation. The complex interplay of gravitational and frictional forces causes the cloud to condense and heat. Some of the gas is ejected from the system with each orbit of the black holes. F. Goicovic et al. 2016 Hernández-García and her team plan to continue observations of AT 2021hdr to better understand the system and improve their models. They’re also interested in studying its home galaxy, which is currently merging with another one nearby — an event first reported in their paper.
“As Swift approaches its 20th anniversary, it’s incredible to see all the new science it’s still helping the community accomplish,” said S. Bradley Cenko, Swift’s principal investigator at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “There’s still so much it has left to teach us about our ever-changing cosmos.”
NASA’s missions are part of a growing, worldwide network watching for changes in the sky to solve mysteries of how the universe works.
Goddard manages the Swift mission in collaboration with Penn State, the Los Alamos National Laboratory in New Mexico, and Northrop Grumman Space Systems in Dulles, Virginia. Other partners include the University of Leicester and Mullard Space Science Laboratory in the United Kingdom, Brera Observatory in Italy, and the Italian Space Agency.
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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 Nov 13, 2024 Editor Jeanette Kazmierczak Related Terms
Astrophysics Black Holes Galaxies, Stars, & Black Holes Galaxies, Stars, & Black Holes Research Goddard Space Flight Center Neil Gehrels Swift Observatory Science & Research Supermassive Black Holes The Universe View the full article
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