Shockwaves resulting from the violent collision between an intruder galaxyGalaxyA large body of gas, dust, stars, and their companions (Planets, asteroids, moons, etc.) held together by their mutual gravitational attraction. They are grouped into three main categories: spiral galaxies, elliptical galaxies, and irregular galaxies. (see below) Another class of galaxies is peculiar galaxies, which are thought to be distorted versions of normal galaxies. and Stephan’s Quintet are helping astronomers to understand how turbulence influences gas in the intergalactic medium. New observations with the Atacama Large Millimeter/submillimeter Array (ALMA) and the James Webb Space Telescope (JWST) have revealed that a sonic boom several times the size of the Milky Way has kickstarted a recycling plant for warm and cold molecular hydrogen gas. What’s more, scientists uncovered the break-up of a giant cloud into a fog of warm gas, the possible collision of two clouds forming a splash of warm gas around them, and the formation of a new galaxy. The observations were presented today in a press conference at the 241st meeting of the American Astronomical Society (AAS) in Seattle, Washington.

Stephan’s Quintet is a group of five galaxies—NGC 7317, NGC 7318a, NGC 7318b, NGC 7319, and NGC 7320— generally located about 270 million light-years from Earth in the constellation Pegasus. The group provides a pristine laboratory for the study of galaxy collisions and their impact on the surrounding environment. Typically galaxy collisions and mergers trigger a burst of star formation; that’s not the case in Stephan’s Quintet. Instead, this violent activity is taking place in the intergalactic medium, away from the galaxies in places where there is little to no star formation to obstruct the view. 

That clean window into the Universe has allowed astronomers to watch what’s happening as one of the galaxies, NGC 7318b, violently intrudes into the group at a relative speed of roughly 800 km/second. At that speed, a trip from Earth to the Moon would take just eight minutes. “As this intruder crashes into the group, it is colliding with an old gas streamer that likely was caused by a previous interaction between two of the other galaxies, and is causing a giant shockwave to form,” said Philip Appleton, an astronomer and senior scientist at Caltech’s IPAC, and lead investigator on the project. “As the shockwave passes through this clumpy streamer, it is creating a highly turbulent, or unsteady, cooling layer, and it’s in the regions affected by this violent activity that we’re seeing unexpected structures and the recycling of molecular hydrogen gas. This is important because molecular hydrogen forms the raw material that may ultimately form stars, so understanding its fate will tell us more about the evolution of Stephan’s Quintet and galaxies in general.”

The new observations using ALMA’s Band 6 (1.3mm wavelength) receiver— developed by the U.S. National Science Foundation‘s National Radio Astronomy Observatory (NRAO)— allowed scientists to zoom into three key regions in extreme detail, and for the first time, build a clear picture of how the hydrogen gas is moving and being shaped on a continuous basis.

“The power of ALMA is obvious in these observations, providing astronomers new insights and better understanding of these previously unknown processes,” said Joe Pesce, Program Officer for ALMA at the U.S. National Science Foundation (NSF).

The region at the center of the main shock wave, dubbed Field 6, revealed a giant cloud of cold molecules that is being broken apart and stretched out into a long tail of warm molecular hydrogen and repeatedly recycled through these same phases. “What we’re seeing is the disintegration of a giant cloud of cold molecules in super-hot gas, and interestingly, the gas doesn’t survive the shock, it just cycles through warm and cold phases,” said Appleton. “We don’t yet fully understand these cycles, but we know the gas is being recycled because the length of the tail is longer than the time it takes for the clouds it is made from to be destroyed.”

This intergalactic recycling plant isn’t the only strange activity resulting from the shockwaves. In the region dubbed Field 5, scientists observed two cold gas clouds connected by a stream of warm molecular hydrogen gas. Curiously, one of the clouds— which resembles a high-speed bullet of cold hydrogen gas colliding with a large thread-like filament of spread out gas— created a ring in the structure as it punched through. The energy caused by this collision is feeding the warm envelope of gas around the region, but scientists aren’t quite sure what that means because they don’t yet have detailed observational data for the warm gas. “A molecular cloud piercing through intergalactic gas, and leaving havoc in its wake, may be rare and not yet fully understood,” said Bjorn Emonts, an astronomer at NRAO and a co-investigator on the project. “​​But our data show that we have taken the next step in understanding the shocking behavior and turbulent life-cycle of molecular gas clouds in Stephan’s Quintet.”   

Perhaps the most “normal” of the bunch is the region dubbed Field 4, where scientists found a steadier, less turbulent environment that allowed hydrogen gas to collapse into a disk of stars and what scientists believe is a small dwarf galaxy in formation. “In field 4, it is likely that pre-existing large clouds of dense gas have become unstable because of the shock, and have collapsed to form new stars as we expect, ” said Pierre Guillard, a researcher at the Institut d’Astrophysique de Paris and a co-investigator on the project, adding that all of the new observations have significant implications for theoretical models of the impact of turbulence in the Universe. “The shock wave in the intergalactic medium of Stephan’s Quintet has formed as much cold molecular gas as we have in our own Milky Way, and yet, it forms stars at a much slower rate than expected. Understanding why this material is sterile is a real challenge for theorists. Additional work is needed to understand the role of high levels of turbulence and efficient mixing between the cold and hot gas.”

Prior to the ALMA observations, scientists had little idea all of this was playing out in the Quintet’s intergalactic medium, but it wasn’t for lack of trying. In 2010, the team used NASA’s Spitzer Space Telescope to observe Stephan’s Quintet and discovered large clouds of warm— estimated to be between 100° to 400° Kelvin, or roughly -280° to 260° Fahrenheit— molecular hydrogen mixed in with the super-hot gas. “These clouds should have been destroyed by the large-scale shockwave moving through the group, but weren’t. And we wanted to know, and still want to know, how did they survive?” said Appleton. 

To solve the mystery, the team needed more and different technological power and capability. ALMA’s first light occurred more than a year later, in late 2011 and JWST captured its first images earlier this year. The combination of these powerful resources has provided strikingly beautiful infrared images of Stephan’s Quintet, and a tantalizing, though incomplete, understanding of the relationship between the cold, warm molecular, and ionized hydrogen gases in the wake of the giant shockwave. The team now needs spectroscopic data to unlock the secrets of the warm molecular hydrogen gas.

“These new observations have given us some answers, but ultimately showed us just how much we don’t yet know,” said Appleton. “While we now have a better understanding of the gas structures and the role of turbulence in creating and sustaining them, future spectroscopic observations will trace the motions of the gas through the doppler effect, tell us how fast the warm gas is moving, allow us to measure the temperature of the warm gas, and see how the gas is being cooled or warmed by the shockwaves. Essentially, we’ve got one side of the story. Now it’s time to get the other.”

About NRAO

The National Radio Astronomy Observatory (NRAO) is a facility of the National Science Foundation, operated under cooperative agreement by Associated Universities, Inc.

About ALMA

The Atacama Large Millimeter/submillimeter Array (ALMA), an international astronomy facility, is a partnership of the European Organisation for Astronomical Research in the Southern Hemisphere (ESO), the U.S. National Science Foundation (NSF) and the National Institutes of Natural Sciences (NINS) of Japan in cooperation with the Republic of Chile. ALMA is funded by ESO on behalf of its Member States, by NSF in cooperation with the National Research Council of Canada (NRC) and the Ministry of Science and Technology (MOST) and by NINS in cooperation with the Academia Sinica (AS) in Taiwan and the Korea Astronomy and Space Science Institute (KASI).

ALMA construction and operations are led by ESO on behalf of its Member States; by the National Radio Astronomy Observatory (NRAO), managed by Associated Universities, Inc. (AUI), on behalf of North America; and by the National Astronomical Observatory of Japan (NAOJ) on behalf of East Asia. The Joint ALMA Observatory (JAO) provides the unified leadership and management of the construction, commissioning and operation of ALMA.

Media Contact:

Amy C. Oliver
Public Information Officer, ALMA
Public Information & News Manager, NRAO
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The design for the Next Generation Very Large Array (ngVLA) prototype antenna has passed an intensive, five-day review, clearing the way to begin manufacturing the prototype antenna. The review in Wiesbaden, Germany was attended by scientists and engineers from the National Science Foundation (NSF), the NSF’s National Radio Astronomy Observatory (NRAO), and mtex antenna technology GmbH, the firm contracted to develop the design and produce the prototype. The NRAO and mtex representatives presented details of the design to a panel of experts — coming from U.S. and South African institutions — independent of the project.

The review panel’s report recommended that the project proceed to manufacturing the prototype antenna. They concluded that the design fulfills ngVLA requirements and is mature enough to be manufactured. While they noted some items that need additional work, they said those items are minor and do not require further external review. The panel also noted the “good, healthy, open and honest working relationship between mtex and NRAO.”

“The antennas are a key element of the ngVLA, and their performance is vital to the success of the entire system. I congratulate the NRAO-mtex team on this important milestone in their development,” said NRAO Director Tony Beasley.

The ngVLA, a powerful radio telescope with 263 dish antennas distributed across North America, is proposed as one of the next generation of cutting-edge astronomical observatories designed to meet the leading research challenges of the coming decades. It will have sensitivity to detect faint objects and resolving power more than 10 times greater than the current VLA.

NRAO and mtex signed a contract in mid-2021 for design of 244, 18-meter diameter antennas and production of a prototype. An additional 19, 6-meter antennas are not part of this contract. Based on NRAO specifications and a conceptual design study, NRAO and mtex have worked intensively to refine the design’s details to a level that allows prototype manufacturing to begin. The project is funded by the NSF.

The prototype will be manufactured by pre-selected suppliers and initially tested in 2023. In early 2024, it will be shipped to the VLA site in New Mexico. The prototype will undergo extensive testing before being integrated into the current VLA. After including any refinements arising from the final round of testing, the design will be ready for mass production, for which a separate contract will be awarded.

“This review confirmed that our colleagues at mtex clearly understand our needs for high quality and performance and also the requirement that the design can be manufactured cost effectively in the numbers needed,” said NRAO’s ngVLA Project Engineer Rob Selena.

In November of 2021, the ngVLA project received high priority from the Astronomy and Astrophysics Decadal Survey (Astro2020) of the U.S. National Academy of Sciences for new ground-based observatories to be constructed during the coming decade. That report said, “The ngVLA facility would be absolutely unique worldwide in both sensitivity and frequency coverage,” and added that its capabilities are “of essential importance to astronomy.” Earlier in 2021, the Canadian Astronomy Long Range Plan 2020-2030 recommended that Canada support the ngVLA.

Last month, NRAO and the Universidad Nacional Autónoma de México (UNAM) signed a memorandum of understanding establishing a collaboration on the ngVLA. The project will require approval by the NSF’s National Science Board and funding by Congress. Full construction could begin by 2025 with early scientific observations starting in 2028 and full scientific operations by 2035.

The ngVLA will have a dense core of antennas and a signal processing center at the current site of the VLA on the Plains of San Agustin in New Mexico. The system will include other antennas located throughout New Mexico and in west Texas, eastern Arizona, and northern Mexico. More far-flung antennas will be located in clusters in Hawaii, Washington, California, Iowa, West Virginia, New Hampshire, Puerto Rico (at Arecibo Observatory), the U.S. Virgin Islands, and Canada. Operations will be conducted at the VLA site and in nearby Socorro, New Mexico, with additional science operations in a metropolitan area to be determined.

The National Radio Astronomy Observatory is a facility of the National Science Foundation, operated under cooperative agreement by Associated Universities, Inc.

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Forty-eight days after suspending observations due to a cyberattack, the Atacama Large Millimeter/submillimeter Array (ALMA) is observing the sky again. The computing staff has worked diligently to rebuild the affected JAO computer system servers and services. This is a crucial milestone in the recovery process. 

On 29 October, ALMA suffered a cyberattack. The computing staff took immediate countermeasures to avoid loss and damage to scientific data and IT infrastructure. The attack affected various critical operational servers and computers. 

“The challenge was to securely restore all the communication and computer systems as quickly as possible. We established an aggressive plan that required coordination with the ALMA partnership worldwide,” explains Jorge Ibsen, Head of the ALMA Computing Department. “Thanks to the active engagement of everyone in the partnership worldwide, especially the Computing, Engineering, and Science Operations staff, and the cybersecurity experts from ESO, NAOJ, and NRAO, we managed to be observing as planned.” 

In the coming weeks, the focus will be on recovering testing infrastructure and systems like the ALMA website and other services, which will allow the recovery of all the functionalities existing before the cyberattack. 

ALMA Director, Sean Dougherty, celebrates that: “It is fantastic to be back doing science observations once again! It has been an enormous challenge to rebuild our systems to return to observing securely. Thanks to everyone at the JAO and across the ALMA partnership for attaining this impressive milestone.” 

Media Contact(s):

Nicolas Lira Turpaud
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ALMA Observatory in Chile
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Public Information Officer, ALMA North America
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Pair of Super-Earths Have 1,000-Mile-Deep Oceans

While the National Science Foundation’s Karl G. Jansky Very Large Array (VLA) and the Atacama Large Millimeter/submillimeter Array (ALMA) frequently reveal important new facts about objects far beyond our own Milky Way Galaxy — at distances of many millions or billions of light-years — they also are vital tools for unraveling much closer mysteries, right here in our own Solar System. A pair of recent scientific papers illustrate how these telescopes are helping planetary scientists understand the workings of the Solar System’s largest planet, Jupiter, and its innermost moon Io.

The National Radio Astronomy Observatory is a facility of the National Science Foundation, operated under cooperative agreement by Associated Universities, Inc.

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Media Contact:
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In the 1997 movie Contact, Ellie Arroway is a young radio astronomer played by Jodie Foster. Ellie’s on a mission to discover alien life, and in one famous scene filmed at the Very Large Array, she sits at the edge of the observatory, listening to the radio sounds of the sky with antenna dishes in the background. It’s a wonderful cinematic moment highlighting Ellie’s lonely search for truth and has become so iconic that many visitors to the VLA take “that shot” of themselves wearing headphones in front of a radio dish. But as beautifully poetic as the scene is, it is Hollywood magic, not hard science. The radio signals from Ellie’s headphones and computer would interfere with the observatory’s sensitive equipment and radio astronomers don’t listen to the sky.

The idea that radio astronomers listen to celestial objects is perhaps the biggest misconception in radio astronomy. And to some degree it’s understandable. People listen to the radio all the time, so surely radio astronomers must do the same. But the sounds we hear on the radio aren’t the sounds of radio itself. They are converted from electrical signals. Sound waves require a medium such as air to travel through, and since space is essentially a vacuum, sounds can’t travel through space. If astronomers did listen to the sky, all they would hear is silence.

Radio is a form of light. It’s just like visible light, but with a much longer wavelength. While visible light has a wavelength on the scale of atoms, radio light has wavelengths ranging from about the thickness of a pencil lead to more than the length of a bus.

Because radio wavelengths are on the human scale, the technology of radio astronomy is often very different from that of optical astronomy. There are broad similarities. Both optical and radio astronomy use reflective surfaces to focus light onto a detector or receiver, which then converts the light into a digital signal. Astronomers can then use this digital signal to create astronomical images. But because radio wavelengths are so much longer than visible wavelengths, we have to achieve this feat in different ways.

One key factor is the size of the reflector. Generally, the larger your reflector or mirror, the more light you can focus and the sharper and brighter your image. This is why the best optical telescopes have mirrors several meters in diameter. But the size of your reflector must scale to that of your wavelength. Since radio waves are thousands of times longer than visible waves, a radio telescope mirror would need to be larger than Manhattan. That isn’t something we can build, so instead, we create arrays of smaller dishes. Each antenna dish acts like a piece of a larger mirror. Astronomers can then simulate a city-wide dish by combining data from the array of smaller dishes.

Another factor is that radio light is often much fainter than visible light, and there are many things that create radio light. This means that radio telescopes need to be protected from everyday objects such as cell phones and computer equipment that emit radio light. The antenna receivers must also be extremely cold. Objects at room temperature emit lots of faint radio light which can affect the accuracy of observational data, so the receivers and other electronics of a radio telescope must be supercooled to convert radio light into a digital signal.

Of course, once astronomers have their data, they can always convert that data into sound. This is most famously done with pulsars, where the electric bursts of energy from a neutron star are converted to audible pops. Astronomers have also converted phenomena such as the turbulent aurora of Jupiter, or the wail of a distant nebula. These sounds can give us an emotional connection to the cosmos, but just like the scene from Contact, they are merely a poetic interpretation of the radio light we capture.

The post Silent as the Night: Why Radio Astronomy Doesn’t Listen to the Sky appeared first on National Radio Astronomy Observatory.

Exhaust from Infalling Comets Makes Space a Dusty Place

Tucked away in a local pocket of dark matter, a late-blooming dwarf galaxy looks like it belongs in the early universe.

Tucked away in a local pocket of dark matter, a late-blooming dwarf galaxy looks like it belongs in the early universe.

The U.S. National Science Foundation’s National Radio Astronomy Observatory (NRAO) and the Universidad Nacional Autónoma de México (UNAM) have signed a memorandum of understanding establishing their collaboration on the Next Generation Very Large Array (ngVLA), a new radio observatory currently in design and development at NRAO.

The signing ceremony was attended by NRAO Director Tony Beasley and UNAM Rector Enrique Graue Wiechers, along with representatives of AUI, NSF, and the federal government of Mexico on November 4, 2022, in Mexico City.

“This new memorandum of understanding between NRAO and UNAM strengthens our existing partnership and is the foundation for important cooperative work on ngVLA, including the future selection of sites for the new array in Mexico,” said Beasley. “We look forward to building the future of radio astronomy with UNAM and our other partners.”

The ngVLA is an upcoming array of 263 radio antennas spread across North America that, once approved and constructed, will address fundamental questions in all major areas of astrophysics, including exoplanets, galaxy formation, and black hole evolution.

“International partnerships are critical for the construction of larger and more complex facilities. It is exciting to see scholars at UNAM and the NRAO working together on the ngVLA,” said Debra Fischer, division director of Astronomical Sciences at NSF. “The best scientific and engineering talent in both countries are attracted to observatories like ngVLA where new discoveries could revolutionize our understanding of the universe.”

The new MOU builds upon prior collaborations between NRAO and UNAM for the design and development of the ngVLA. In August, NRAO announced the appointment of Alfonso Trejo-Cruz, an astronomer at UNAM, to lead site selection and development of ngVLA sites in northern Mexico.

As part of the MOU, UNAM will contribute $1 million over four years to the collaboration to fund site characterization, imaging, and configuration, geolocation, etc.

NSF previously awarded NRAO $23 million for design and development work on a prototype antenna in 2021, a process that is nearing completion. Once approved, construction on the ngVLA could begin as soon as 2026, with projected early scientific observations starting in 2029 and full scientific operations by 2035.

The National Radio Astronomy Observatory is a facility of the National Science Foundation, operated under cooperative agreement by Associated Universities, Inc.

About Universidad Nacional Autónoma de México

UNAM is the largest university in Latin America and carries out education, research, and innovation in all disciplines. UNAM has campuses and research stations in most states across Mexico, and harbors numerous services and national institutions, fostering social mobility and contributing to Mexico’s development for the future.

Media Contact:

Amy C. Oliver, FRAS
Public Information & News Manager, NRAO
Public Information Officer, ngVLA
aoliver@nrao.edu
+1-434-242-9584

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