- NASA Unveils Submarine Design for Exploring Titan’s Seas
- Mismatched Twin Stars Spotted in the Delivery Room
- Virgin Galactic Opens New Facility for Small Satellite Launch Vehicle, LauncherOne
- Research on Apollo Samples Refines Lunar Impact History
- A Full Day on Pluto and its Moon Charon
- A New Way to View Titan: 'Despeckle' It
- Exploded Star Blooms Like a Cosmic Flower
- Astronomers Catch a Multiple Star System in the Process of Forming
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Posted: 13 Feb 2015 05:03 AM PST
NASA has unveiled at this year's Innovative Advanced Concepts (NIAC) Symposium a possible design for a submersible robot for use in exploring the liquid methane/ethane seas on Saturn's moon Titan. The video and sub design were created by NASA Glenn's COMPASS Team along with some researchers from Applied Research Lab. The call for the design came from workers with the NASA NIAC Program, which of course is tasked with coming up with ideas for new ways to explore space and the celestial bodies in it. The sub, which the team has dubbed the Titan Submarine Phase I Conceptual Design, looks reminiscent of early subs on Earth such as those developed for use in the Civil War. The technology onboard, would be anything but old, of course, as it would have to be able to operate mostly autonomously in a very hostile and distant environment.
The most likely place for deployment of the sub would be Kraken Mare—Titan's largest polar sea. Data from probes has found that the sea covers approximately 154,000 square miles with depths as deep as 525 feet. The sea is not idle, either—it has currents and a tide, both of which could make keeping the sub safe from harm a serious challenge. Whereas most planetary landers are somewhat equant in shape, and are comfortably accommodated in circularly-symmetric blunt sphere-cone entry shields, the elongate configuration of the submersible is not. However, the thick Titan atmosphere is a relatively gentle cushion for hypersonic entry from space, and we find our vehicle can be readily integrated with and deployed from a spaceplane carrier. Specifically, the submersible can fit within the cargo area of a modified Air Force X-37 lifting body, and could exploit its crossrange flight ability to reach any desired delivery point a few km over Kraken.
The vehicle would use conventional propulsors to yaw around, using a sun sensor to determine the initial azimuth to Earth and begin communication, using a terrestrial radio beacon as a more precise reference. After initial trials to determine dynamic characteristics in-situ and verify guidance/performance models, the vehicle would begin its scientific traverse.
There would also be the problem of communicating with it. The researchers envision a system where the sub surfaces for 16 hours at a time, sending signals directly to Earth (which would take almost an hour and a half to get here). As an undersea vehicle, it would not be able to use solar power either, so the team envisions a radiothermal Stirling generator for propulsion. Also, because of the extreme cold, a special piston driven type of system would have to be developed to prevent freezing of (likely nitrogen) ballast. Though it is still not clear exactly what the sub might be looking for, one sure bet is it would be searching for compounds that might indicate life once existed in the sea or perhaps offer clues as to how life began back here on Earth. NASA expects some sort of sub might be ready for a journey to Titan by 2040, which would mark the first time such a mission has not been conducted on dry land. To get it there, they envision a winged craft that makes its way to the surface, then sinks beneath the waves on Kraken Mare, leaving the sub to discover what lies beneath. Credit: phys.org, hou.usra.edu  | ||||||
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Posted: 13 Feb 2015 03:31 AM PST
The majority of stars in our galaxy come in pairs. In particular, the most massive stars usually have a companion. These fraternal twins tend to be somewhat equal partners when it comes to mass - but not always. In a quest to find mismatched star pairs known as extreme mass-ratio binaries, astronomers have discovered a new class of binary stars. One star is fully formed while the other is still in its infancy. "We caught them at just the right time. In effect, we're seeing these stars in the delivery room," says lead author Maxwell Moe of the Harvard-Smithsonian Center for Astrophysics (CfA). The more massive a star is, the brighter it shines. This makes it difficult to identify extreme mass-ratio binaries because the heavier star outshines, and thereby hides, the lighter star.
To combat this effect Moe and his CfA colleague Rosanne DiStefano looked for eclipsing systems, in which the two stars line up in such a way that they periodically pass in front of each other as seen from Earth. When the fainter star eclipses the brighter star, their combined light drops detectably. These systems are rare because they require a precise alignment as seen from Earth. After sifting through thousands of eclipsing systems, they identified 18 extreme mass-ratio binaries in a neighboring galaxy called the Large Magellanic Cloud. The stars circle each other tightly in orbits with periods of 3 to 9 days. The more massive stars weigh 6 to 16 times as much as the Sun, while the less massive stars weigh about 1 to 2 times the Sun. A clue to the young nature of these systems came from an unusual feature in the data. The fainter star shows illumination phases, just like phases of the moon, as the two stars orbit each other. This indicates that the companion is reflecting the light of the brighter, more massive star. We only see phases because the fainter and less massive companion is not yet a full-fledged star. Astronomers describe it as being "pre-main sequence." A star forms when a giant clump of gas pulls together under its own gravity, growing denser and hotter until nuclear fusion ignites. This process happens faster for more massive stars. "Imagine if a human baby shrank as it got older instead of growing. That's what happens for young stars," says DiStefano. In the young systems this research identified, the more massive star is already on the main sequence, while the less massive companion is not. As a result, that companion is puffier than it would be, since it is still contracting. This effectively lets the pre-main sequence star act as a giant mirror, reflecting the brilliance of its partner. The discovery of these stellar twins could provide invaluable insight into the formation and evolution of massive stars, close binaries, and star nurseries. These 18 systems were culled from millions of stars in the Large Magellanic Cloud observed by the Optical Gravitational Lensing Experiment. Due to their rarity, finding examples in our galaxy likely will require an extensive survey using facilities like the upcoming Large Synoptic Survey Telescope. This research has been accepted for publication in The Astrophysical Journal. Credit: cfa.harvard.edu  | ||||||
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Posted: 13 Feb 2015 02:19 AM PST
Virgin Galactic has announced it has leased a new 150,000 square foot facility that will house design and manufacturing of the company’s small satellite launch vehicle, LauncherOne. LauncherOne is a new two-stage orbital launch vehicle being designed by Virgin Galactic specifically to launch commercial or governmental satellites that weigh 500 pounds (225 kilograms) or less. Much like SpaceShipTwo, the company’s reusable vehicle for space tourism, LauncherOne is designed to be launched from the WhiteKnightTwo carrier aircraft, giving customers the ability to avoid crowded and expensive launch ranges while also picking the launch location best suited for their mission. Located at the Long Beach Airport, this new facility will allow easy transportation of rockets and of customers’ satellites using WhiteKnightTwo.
Virgin Galactic CEO George Whitesides said, “The technical progress our team has made designing and testing LauncherOne has enabled a move into a dedicated facility to produce the rocket at quantity. With New Mexico’s magnificent Spaceport America for our commercial spaceflight operations, our Mojave facilities for WhiteKnightTwo and SpaceShipTwo production, and now our new facility in Long Beach for LauncherOne, we are building capability to serve our expanding customer community.” Virgin Galactic will be hosting a job fair and open house at the new facility on Saturday March 7. Prospective applicants looking for more information should visit virgingalactic.com in the coming days for complete job listings and for more information on the open house. With a launch price aimed to be the lowest in the nation or perhaps the world, LauncherOne has already attracted the interest of numerous small satellite manufacturers and operators. Among them is the recently announced OneWeb project designed to deliver broadband services to areas of the world not currently served by terrestrial networks. This and other ambitious projects are expected keep the Long Beach facility busy for many years to come. US Congressman Alan Lowenthal expressed his support regarding Virgin Galactic’s move to the area, saying. “I want to welcome Virgin Galactic to Long Beach and I applaud their commitment both to the state and to Southern California. This proves again that Southern California has the tools, the skills, and the talent to push not only the bounds of technology, but in this case, the bonds of Earth itself.” “California and Los Angeles County have always been home to the true pioneers of the aerospace business,” said Long Beach Mayor Robert Garcia. “We’re thrilled that Long Beach attracted a tenant like Virgin Galactic, a world-renowned leader of the commercial space industry. This is one of the most exciting and dynamic businesses in the country, and they are bringing excellent jobs we need for the talented and hard-working aerospace professionals who already call Long Beach home.” “I’m extremely proud that Virgin Galactic has chosen Long Beach for its new facility and excited to welcome them to the community,” said Long Beach 5th District Councilwoman Stacy Mungo. “I have great respect for our aviation history, and this innovative satellite project will bring a spotlight to Long Beach and to our partnerships for economic development.” Credit: virgingalactic.com  | ||||||
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Posted: 13 Feb 2015 01:36 AM PST
It’s been more than 40 years since astronauts returned the last Apollo samples from the moon, and since then those samples have undergone some of the most extensive and comprehensive analysis of any geological collection. A team led by Arizona State University (ASU) researchers has now refined the timeline of meteorite impacts on the moon through a pioneering application of laser microprobe technology to Apollo 17 samples. Impact cratering is the most ubiquitous geologic process affecting the solid surfaces of planetary bodies in the solar system. The moon’s scarred surface serves as a record of meteorite bombardment that spans much of solar system history.
Developing an absolute chronology of lunar impact events is of particular interest because the moon is an important proxy for understanding the early bombardment history of Earth, which has been largely erased by plate tectonics and erosion, and because we can use the lunar impact record to infer the ages of other cratered surfaces in the inner solar system. Researchers in ASU’s Group 18 Laboratories, headed by professor Kip Hodges, used an ultraviolet laser microprobe, attached to a high-sensitivity mass spectrometer, to analyze argon isotopes in samples returned by Apollo 17. While the technique has been applied to a large number of problems in Earth’s geochronology, this is the first time it has been applied to samples from the Apollo archive. The samples analyzed by the ASU team are known as lunar impact melt breccias – mash-ups of glass, rock and crystal fragments that were created by impact events on the moon’s surface. When a meteor strikes another planetary body, the impact produces very large amounts of energy – some of which goes into shock, heating and melting the target rocks. These extreme conditions can "restart the clock" for material melted during impact. As a result, the absolute ages of lunar craters are primarily determined through isotope geochronology of components of the target rocks that were shocked and heated to the point of melting, and which have since solidified.
However, lunar rocks may have experienced multiple impact events over the course of billions of years of bombardment, potentially complicating attempts to date samples and relate the results to the ages of particular impact structures. Conventional wisdom holds that the largest impact basins on the moon were responsible for generating the vast majority of impact melts, and therefore nearly all of the samples dated must be related to the formation of those basins. While it is true that enormous quantities of impact melt are generated by basin-scale impact events, recent images taken by the Lunar Reconnaissance Orbiter Camera confirm that even small craters with diameters on the order of 100 meters can generate impact melts. The team’s findings have important implications for this particular observation. The results are published in the inaugural issue of the American Association for the Advancement of Science’s newest journal, Science Advances, on Feb. 12. “One of the samples we analyzed, 77115, records evidence for only one impact event, which may or may not be related to a basin-forming impact event. In contrast, we found that the other sample, 73217, preserves evidence for at least three impact events occurring over several hundred million years, not all of which can be related to basin-scale impacts,” says Cameron Mercer, lead author of the paper and a graduate student in ASU’s School of Earth and Space Exploration. Sample 77115, collected by astronauts Gene Cernan and Harrison Schmitt at Station 7 during their third and final moonwalk, records a single melt-forming event about 3.83 billion years ago. Sample 73217, retrieved at Station 3 during the astronauts’ second moonwalk, preserves evidence for at least three distinct impact melt-forming events occurring between 3.81 billion years ago and 3.27 billion years ago. The findings suggest that a single small sample can preserve multiple generations of melt products created by impact events over the course of billions of years. “Our results emphasize the need for care in how we analyze samples in the context of impact dating, particularly for those samples that appear to have complex, polygenetic origins. This applies to both the samples that we currently have in our lunar and meteoritic collections, as well as samples that we recover during future human and robotic space exploration missions in the inner solar system,” says Mercer. Credit: asu.edu  | ||||||
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Posted: 12 Feb 2015 02:10 PM PST
A time-lapse “movie” of Pluto and its largest moon, Charon, was recently shot at record-setting distances with the Long-Range Reconnaissance Imager (LORRI) on NASA’s New Horizons spacecraft. The movie was made over about a week, from Jan. 25-31, 2015. It was taken as part of the mission’s second optical navigation (“OpNav”) campaign to better refine the locations of Pluto and Charon in preparation for the spacecraft’s close encounter with the small planet and its five moons on July 14, 2015. Pluto and Charon were observed for an entire rotation of each body; a “day” on Pluto and Charon is 6.4 Earth days. The first of the images was taken when New Horizons was about 3 billion miles from Earth, but just 126 million miles (203 million kilometers) from Pluto – about 30% farther than Earth’s distance from the Sun. The last frame came 6½ days later, with New Horizons more than 5 million miles (8 million kilometers) closer.
The wobble easily visible in Pluto’s motion, as Charon orbits, is due to the gravity of Charon, which is about one-eighth as massive as Pluto and about the size of Texas.
Faint stars can be seen in background of these images. Each frame had an exposure time of one-tenth of a second, too short to see Pluto’s smaller, much fainter moons. New Horizons is still too far from Pluto and its moons to resolve surface features.
The close up look at Pluto and Charon below, taken as part of the mission’s latest optical navigation (“OpNav”) campaign from Jan. 25-31, 2015, comes from the Long Range Reconnaissance Imager (LORRI) on NASA;s New Horizons spacecraft.
The time-lapse frames in this movie were magnified four times to make it easier to see Pluto and Charon orbit around their barycenter, a mutual point above Pluto’s surface where Pluto and Charon’s gravity cancels out – this is why Pluto appears to “wobble” in space. Charon orbits approximately 11,200 miles (about 18,000 kilometers) above Pluto’s surface.
Each frame had an exposure time of one-tenth of a second, too short to see Pluto’s smaller, much fainter moons.
"These images allow the New Horizons navigators to refine the positions of Pluto and Charon, and they have the additional benefit of allowing the mission scientists to study the variations in brightness of Pluto and Charon as they rotate, providing a preview of what to expect during the close encounter in July," says Alan Stern, the New Horizons principal investigator from the Southwest Research Institute in Boulder, Colorado.
The Johns Hopkins University Applied Physics Laboratory manages the New Horizons mission for NASA's Science Mission Directorate in Washington. Alan Stern, of the Southwest Research Institute (SwRI), headquartered in San Antonio, is the principal investigator and leads the mission. SwRI leads the science team, payload operations, and encounter science planning. New Horizons is part of the New Frontiers Program managed by NASA's Marshall Space Flight Center in Huntsville, Alabama. APL designed, built and operates the spacecraft.
Credit: pluto.jhuapl.edu
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Posted: 12 Feb 2015 01:40 PM PST
During 10 years of discovery, NASA's Cassini spacecraft has pulled back the smoggy veil that obscures the surface of Titan, Saturn's largest moon. Cassini's radar instrument has mapped almost half of the giant moon's surface; revealed vast, desert-like expanses of sand dunes; and plumbed the depths of expansive hydrocarbon seas. What could make that scientific bounty even more amazing? Well, what if the radar images could look even better? Thanks to a recently developed technique for handling noise in Cassini's radar images, these views now have a whole new look. The technique, referred to by its developers as "despeckling," produces images of Titan's surface that are much clearer and easier to look at than the views to which scientists and the public have grown accustomed.
Typically, Cassini's radar images have a characteristic grainy appearance. This "speckle noise" can make it difficult for scientists to interpret small-scale features or identify changes in images of the same area taken at different times. Despeckling uses an algorithm to modify the noise, resulting in clearer views that can be easier for researchers to interpret.
Antoine Lucas got the idea to apply this new technique while working with members of Cassini's radar team when he was a postdoctoral researcher at the California Institute of Technology in Pasadena.
"Noise in the images gave me headaches," said Lucas, who now works at the astrophysics division of France's nuclear center (CEA). Knowing that mathematical models for handling the noise might be helpful, Lucas searched through research published by that community, which is somewhat disconnected from people working directly with scientific data. He found that a team near Paris was working on a “de-noising” algorithm, and he began working with them to adapt their model to the Cassini radar data. The collaboration resulted in some new and innovative analysis techniques.
"My headaches were gone, and more importantly, we were able to go further in our understanding of Titan’s surface using the new technique," Lucas said.
As helpful as the tool has been, for now, it is being used selectively.
"This is an amazing technique, and Antoine has done a great job of showing that we can trust it not to put features into the images that aren’t really there," said Randy Kirk, a Cassini radar team member from the U.S. Geologic Survey in Flagstaff, Arizona. Kirk said the radar team is going to have to prioritize which images are the most important to applying the technique. "It takes a lot of computation, and at the moment quite a bit of 'fine-tuning' to get the best results with each new image, so for now we'll likely be despeckling only the most important -- or most puzzling -- images," Kirk said.
Despeckling Cassini's radar images has a variety of scientific benefits. Lucas and colleagues have shown that they can produce 3-D maps, called digital elevation maps, of Titan's surface with greatly improved quality. With clearer views of river channels, lake shorelines and windswept dunes, researchers are also able to perform more precise analyses of processes shaping Titan's surface. And Lucas suspects that the speckle noise itself, when analyzed separately, may hold information about properties of the surface and subsurface.
"This new technique provides a fresh look at the data, which helps us better understand the original images," said Stephen Wall, deputy team lead of Cassini's radar team, which is based at NASA's Jet Propulsion Laboratory in Pasadena, California. "With this innovative new tool, we will look for details that help us to distinguish among the different processes that shape Titan’s surface," he said.
Details about the new technique were published recently in the Journal of Geophysical Research: Planets.
The Cassini-Huygens mission is a cooperative project of NASA, ESA (European Space Agency) and the Italian Space Agency. NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington. JPL designed, developed and assembled the Cassini orbiter. The radar instrument was built by JPL and the Italian Space Agency, working with team members from the US and several European countries.
Credit: saturn.jpl.nasa.gov
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Posted: 12 Feb 2015 12:48 PM PST
Because the debris fields of exploded stars, known as supernova remnants, are very hot, energetic, and glow brightly in X-ray light, NASA's Chandra X-ray Observatory has proven to be a valuable tool in studying them. The supernova remnant called G299.2-2.9 (or G299 for short) is located within our Milky Way galaxy, but Chandra'snew image of it is reminiscent of a beautiful flower here on Earth. G299 was left over by a particular class of supernovas called Type Ia. Astronomers think that a Type Ia supernova is a thermonuclear explosion - involving the fusion of elements and release of vast amounts of energy - of a white dwarf star in a tight orbit with a companion star. If the white dwarf's partner is a typical, Sun-like star, the white dwarf can become unstable and explode as it draws material from its companion. Alternatively, the white dwarf is in orbit with another white dwarf, the two may merge and can trigger an explosion.
Regardless of their triggering mechanism, Type Ia supernovas have long been known to be uniform in their extreme brightness, usually outshining the entire galaxy where they are found. This is important because scientists use these objects as cosmic mileposts, allowing them to accurately measure the distances of galaxies billions of light years away, and to determine the rate of expansion of the Universe.
Traditional theoretical models of Type Ia supernovas generally predict that these explosions would be symmetric, creating a near perfect sphere as they expand. These models have been supported by results showing that remnants of Type Ia supernovas are more symmetric than remnants of supernovas involving the collapse of massive stars.
However, astronomers are discovering that some Type Ia supernova explosions may not be as symmetric as previously thought. G299 could be an example of such an "unusual" Type Ia supernova. Using a long observation from Chandra, researchers discovered the shell of debris from the exploded star is expanding differently in various directions.
In this new Chandra image, red, green, and blue represent low, medium, and high-energy X-rays, respectively, detected by the telescope. The medium energy X-rays include emission from iron and the hard-energy X-rays include emission from silicon and sulfur. The X-ray data have been combined with infrared data from ground-based 2MASS survey that shows the stars in the field of view.
By performing a detailed analysis of the X-rays, researchers found several clear examples of asymmetry in G299. For example, the ratio between the amounts of iron and silicon in the part of the remnant just above the center is larger than in the part of the remnant just below the center. This difference can be seen in the greener color of the upper region compared to the bluer color of the lower region. Also, there is a strongly elongated portion of the remnant extending to the right. In this region, the relative amount of iron to silicon is similar to that found in the southern region of the remnant.
The patterns seen in the Chandra data suggest that a very lopsided explosion may have produced this Type Ia supernova. It might also be that the remnant has been expanding into an environment where the medium it encountered was uneven. Regardless of the ultimate explanation, observations of G299 and others like it are showing astronomers just how varied such beautiful cosmic flowers can be.
A paper describing these results was published in the September 1st, 2014 issue of The Astrophysical Journal, and is available online. The authors are Seth Post and Sangwook Park from the University of Texas at Arlington in Texas; Carles Badenes from the University of Pittsburgh, in Pittsburgh, Pennsylvania; David Burrows from Pennsylvania State University in University Park, Pennsylvania; John Hughes from Rutgers University in Piscataway, New Jersey; Jae-Joon Lee from the Korea Astronomy and Space Science Institute; Koji Mori from the University of Miyazaki in Japan and Patrick Slane from the Harvard-Smithsonian Center of Astrophysics in Cambridge, Massachusetts.
NASA's Marshall Space Flight Center in Huntsville, Alabama, manages the Chandra program for NASA's Science Mission Directorate in Washington. The Smithsonian Astrophysical Observatory in Cambridge, Massachusetts, controls Chandra's science and flight operations.
Credit: chandra.si.edu
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Posted: 12 Feb 2015 12:22 PM PST
For the first time, astronomers have caught a multiple-star system in the beginning stages of its formation, and their direct observations of this process give strong support to one of several suggested pathways to producing such systems. The scientists looked at a cloud of gas some 800 light-years from Earth, homing in on a core of gas that contains one young protostar and three dense condensations that they say will collapse into stars in the astronomically-short period of 40,000 years. Of the eventual four stars, the astronomers predict that three may become a stable triple-star system. "Seeing such a multiple star system in its early stages of formation has been a longstanding challenge, but the combination of the Very Large Array (VLA) and the Green Bank Telescope (GBT) has given us the first look at such a young system," said Jaime Pineda, of the Institute for Astronomy, ETH Zurich, in Switzerland.
The scientists used the VLA and GBT, along with the James Clerk Maxwell Telescope (JCMT) in Hawaii, to study a dense core of gas called Barnard 5 (B5) in a region where young stars are forming in the constellation Perseus. This object was known to contain one young forming star.
When the research team led by Pineda used the VLA to map radio emission from methane molecules, they discovered that filaments of gas in B5 are fragmenting, and the fragments are beginning to form into additional stars that will become a multiple-star system.
"We know that these stars eventually will form a multi-star system because our observations show that these gas condensations are gravitationally bound," Pineda said. "This is the first time we've been able to show that such a young system is gravitationally bound," he added.
"This provides fantastic evidence that fragmentation of gas filaments is a process that can produce multiple-star systems," Pineda said. Other proposed mechanisms include fragmentation of the main gas core, fragmentation within a disk of material orbiting a young star, and gravitational capture. "We've now convincingly added fragmentation of gas filaments to this list," Pineda added.
The condensations in B5 that will produce stars now range from one-tenth to more than one-third the mass of the Sun, the scientists said. Their separations will range from 3,000 to 11,000 times the Earth-Sun distance.
The astronomers analyzed the dynamics of the gas condensations and predict that, when they form into stars, they will form a stable system of an inner binary, orbited by a more-distant third star. The fourth star, they suggest, will not long remain part of the system.
"Nearly half of all stars are in multiple systems, but catching such systems at the very early stages of formation has been challenging. Thanks to the combination of the VLA and the GBT, we now have some important new insight into how multiple systems form. Our next step will be to look at other star-forming regions using the new capabilities of the VLA and of the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile," Pineda said.
Unfortunately, the knowledge gained from witnessing this system as it is forming does not include signatures or characteristics to help astronomers locate more like it. “We would like to know how common this configuration is,” said Stella Offner, University of Massachusetts Amherst astrophysicist. “Unfortunately, we couldn’t predict what was there from the initial GBT survey, so we don’t know what to look for in other places. It will take more survey work and more numerical modeling to be able to identify other very young systems like this one.”
The international research team included members from the U.S., the UK, Germany, and Chile. The astronomers reported their findings in the 12 February edition of the scientific journal Nature.
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.gif "Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute")
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