Interconnected stellar nurseries form the largest gaseous structure ever observed in the Milky Way galaxy.
Astronomers at Harvard University have discovered a monolithic, wave-shaped gaseous structure — the largest ever seen in our galaxy — made up of interconnected stellar nurseries. Dubbed the “Radcliffe Wave” in honor of the collaboration’s home base, the Radcliffe Institute for Advanced Study, the discovery transforms a 150-year-old vision of nearby stellar nurseries as an expanding ring into one featuring an undulating, star-forming filament that reaches trillions of miles above and below the galactic disk.
“No astronomer expected that we live next to a giant, wave-like collection of gas — or that it forms the local arm of the Milky Way.” — Alyssa Goodman
The work, published in Nature on January 7, 2020, was enabled by a new analysis of data from the European Space Agency’s Gaia spacecraft, launched in 2013 with the mission of precisely measuring the position, distance, and motion of the stars. The research team’s innovative approach combined the super-accurate data from Gaia with other measurements to construct a detailed, 3D map of interstellar matter in the Milky Way, and noticed an unexpected pattern in the spiral arm closest to Earth.
The researchers discovered a long, thin structure, about 9,000 light-years long and 400 light-years wide, with a wave-like shape, cresting 500 light-years above and below the mid-plane of our galaxy’s disk. The Wave includes many of the stellar nurseries that were thought to form part of “Gould’s Belt,” a band of star-forming regions believed to be oriented in a ring around the sun.
“No astronomer expected that we live next to a giant, wave-like collection of gas — or that it forms the local arm of the Milky Way,” said Alyssa Goodman, the Robert Wheeler Willson Professor of Applied Astronomy, research associate at the Smithsonian Institution, and co-director of the Science Program at the Radcliffe Institute for Advanced Study. “We were completely shocked when we first realized how long and straight the Radcliffe Wave is, looking down on it from above in 3D — but how sinusoidal it is when viewed from Earth. The Wave’s very existence is forcing us to rethink our understanding of the Milky Way’s 3D structure.”
“Gould and Herschel both observed bright stars forming in an arc projected on the sky, so for a long time, people have been trying to figure out if these molecular clouds actually form a ring in 3D,” said João Alves, a professor of physics and astronomy at the University of Vienna and 2018‒2019 Radcliffe Fellow. “Instead, what we’ve observed is the largest coherent gas structure we know of in the galaxy, organized not in a ring but in a massive, undulating filament. The sun lies only 500 light-years from the Wave at its closest point. It’s been right in front of our eyes all the time, but we couldn’t see it until now.”
The new, 3D map shows our galactic neighborhood in a new light, giving researchers a revised view of the Milky Way and opening the door to other major discoveries.
“We don’t know what causes this shape, but it could be like a ripple in a pond, as if something extraordinarily massive landed in our galaxy,” said Alves. “What we do know is that our sun interacts with this structure. It passed by a festival of supernovae as it crossed Orion 13 million years ago, and in another 13 million years it will cross the structure again, sort of like we are ‘surfing the wave.’”
An insider’s view of the galaxy
Disentangling structures in the “dusty” galactic neighborhood within which we sit is a longstanding challenge in astronomy. In earlier studies, the research group of Douglas Finkbeiner, professor of astronomy and physics at Harvard, pioneered advanced statistical techniques to map the 3D distribution of dust using vast surveys of stars’ colors. Armed with new data from Gaia, Harvard graduate students Catherine Zucker and Joshua Speagle recently augmented these techniques, dramatically improving astronomers’ ability to measure distances to star-forming regions. That work, led by Zucker, is published in the Astrophysical Journal.
“We suspected there might be larger structures that we just couldn’t put in context. So, to create an accurate map of our solar neighborhood, we combined observations from space telescopes like Gaia with astrostatistics, data visualization, and numerical simulations,” explained Zucker, a National Science Foundation graduate fellow and a Ph.D. candidate in the Department of Astronomy at Harvard’s Graduate School of Arts and Sciences.
Zucker played a key role in compiling the largest-ever catalog of accurate distances to local stellar nurseries — the basis for the 3D map used in the study. She has set herself the goal of painting a new picture of the Milky Way, near and far.
“We pulled this team together so we could go beyond processing and tabulating the data to actively visualizing it — not just for ourselves but for everyone. Now, we can literally see the Milky Way with new eyes,” she said.
“Studying stellar births is complicated by imperfect data. We risk getting the details wrong, because if you’re confused about distance, you’re confused about size,” said Finkbeiner.
Goodman agreed, “All of the stars in the universe, including our sun, are formed in dynamic, collapsing, clouds of gas and dust. But determining how much mass the clouds have, how large they are, has been difficult, because these properties depend on how far away the cloud is.”
A universe of data
According to Goodman, scientists have been studying dense clouds of gas and dust between the stars for more than 100 years, zooming in on these regions with ever-higher resolution. Before Gaia, there was no data set expansive enough to reveal the galaxy’s structure on large scales. Since its launch in 2013, the space observatory has enabled measurements of the distances to one billion stars in the Milky Way.
The flood of data from Gaia served as the perfect testbed for innovative, new statistical methods that reveal the shape of local stellar nurseries and their connection to the Milky Way’s galactic structure. Alves came to Radcliffe to work with Zucker and Goodman, as they anticipated the flood of data from Gaia would enhance the Finkbeiner group’s “3D Dust Mapping” technology enough to reveal the distances of local stellar nurseries. But they had no idea they would find the Radcliffe Wave.
The Finkbeiner, Alves, and Goodman groups collaborated closely on this data-science effort. The Finkbeiner group developed the statistical framework needed to infer the 3D distribution of the dust clouds; the Alves group contributed deep expertise on stars, star formation, and Gaia; and the Goodman group developed the 3D visualizations and analytic framework, called “glue,” that allowed the Radcliffe Wave to be seen, explored, and quantitatively described.
This study was supported by the NSF Graduate Research Fellowship Program (grant no. 1650114, AST-1614941), the Harvard Data Science Initiative, NASA through ADAP (grant no. NNH17AE75I), and a Hubble Fellowship (grant HST-HF2-51367.001-A) awarded by the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., for NASA, under contract NAS 5-26555.
“A Galactic-scale gas wave in the solar neighborhood” by João Alves, Catherine Zucker, Alyssa A. Goodman, Joshua S. Speagle, Stefan Meingast, Thomas Robitaille, Douglas P. Finkbeiner, Edward F. Schlafly and Gregory M. Green, 7 January 2020, Nature.
“A 3D Dust Map Based on Gaia, Pan-STARRS 1, and 2MASS” by Gregory M. Green, Edward Schlafly, Catherine Zucker, Joshua S. Speagle and Douglas Finkbeiner, 13 December 2019, The Astrophysical Journal.
The articles, analyzed data (on the Harvard Dataverse), statistical code, interactive figures, videos, and WorldWide Telescope tour are all freely available to everyone through a dedicated website.
Australia must commit to carbon cuts to keep green energy advantage -Fortescue’s Forrest
Australia risks losing its advantage in the green energy revolution if its leaders don’t promptly commit to cutting carbon emissions by 2050, the country’s richest man, Fortescue Metals Group founder Andrew Forrest said on Monday.
Forrest, who grew Fortescue from a minnow to rival the world’s biggest mining giants in less than two decades, has spearheaded his company’s global green energy drive, signing deals from Brazil to Indonesia to Democratic Republic of Congo.
The company aims to build a 250 megawatt hydrogen electrolyser at Bell Bay in Tasmania — 25 times the size of the biggest existing electrolysers in the world — for less than A$1 billion ($740 million), Forrest said, putting a price on the project for the first time.
Fortescue is ready to make a final investment decision this year, as promised, but is waiting for support from the state government before going ahead with the project.
While Forrest told Reuters that Australia is the best place to realise his green vision, the country’s failure to commit to a policy to cut emissions is risking that advantage.
“I would say 2050 neutrality is a certainty for Australia. If we support it by COP26 the dividend flow to regional Australia will be substantial. If we don’t support it by COP26, the future will remain uncertain,” Forrest said, referring to the COP 26 climate conference in Glasgow at the end of October.
“The renewable energy, green hydrogen, green ammonia, green electricity industry is very, very mobile,” he said.
“It is where the will is strongest – they will be the first to be developed.”
Australia’s energy policy is again in the spotlight as Prime Minister Scott Morrison prepares to attend the conference, where global leaders will meet to set further climate goals to follow on from the landmark 2015 Paris accord.
But Morrison is short on updated climate ambitions to bring to the table given his reliance on the junior partner in Australia’s coalition government which said it would not be rushed into a decision on whether to support a target of net zero emissions by 2050.
The Nationals who represent coal and farming heartlands worry that stronger emissions targets will cost jobs. Coal is the country’s second biggest export earner.
But Forrest, speaking to Reuters from London, said that rural Australians were set to be the biggest winners in the move to green energy – if agreements are made in time.
“I have demonstrated investment into the regions despite the fact Australia is dragging the chain,” Forrest told Reuters.
Fortescue is investigating the potential to convert top Australian fertiliser maker Incitec Pivot’s Brisbane ammonia plant to use green hydrogen as a feedstock instead of natural gas, with an on-site electrolysis plant that will produce up to 50,000 tonnes of hydrogen a year.
The plant’s future had been under threat due to soaring gas prices, however setting up a green hydrogen production site to feed the existing plant could save 400 jobs and create many more, Forrest said.
At the same time, the product from the plant will be cheaper for local farmers.
“So farmers in Australia long into the future can plan for the next season, or even for the next generation … knowing that fertilisers are coming from a hydrogen molecule that is infinite,” Forrest said.
(Reporting by Melanie Burton and Sonali Paul; Editing by Kirsten Donovan)
Russian filmmakers back on Earth after shoot aboard space station – World News – Castanet.net
A Soyuz space capsule carrying a cosmonaut and two Russian filmmakers has landed after a 3 1/2-hour trip from the International Space Station.
The capsule, descending under a red-and-white striped parachute after entering Earth’s atmosphere, landed upright in the steppes of Kazakhstan on schedule Sunday with Oleg Novitskiy, Yulia Peresild and Klim Shipenko aboard.
Actress Peresild and film director Shipenko rocketed to the space station on Oct. 5 for a 12-day stint to film segments of a movie titled “Challenge,” in which a surgeon played by Peresild rushes to the space station to save a crew member who needs an urgent operation in orbit. Novitskiy, who spent more than six months aboard the space station, is to star as the ailing cosmonaut in the movie.
After the landing, which sent plumes of dust flying high in the air, ground crews extracted the three space flyers from the capsule and placed them in seats set up nearby as they adjusted to the pull of gravity. They were then taken to a medical tent for examination.
All appeared healthy and cheerful. Peresild smiled and held a large bouquet of white flowers as journalists clustered around her. But she said she also felt a touch of melancholy.
“I’m feeling a bit sad today. It seemed that 12 days would be a lot, but I did not want to leave when everything was over,” Peresild said on state TV.
The transfer to the medical tent was delayed for about 10 minutes while crews filmed several takes of Peresild and Novitskiy in their seats, which are to be included in the movie. More scenes remain to be shot on Earth for the film whose release date is uncertain.
Seven astronauts remain aboard the space station: Russia’s Anton Shkaplerov and Pyotr Dubrov; Americans Mark Vande Hei, Shane Kimbrough and Megan McArthur; Thomas Pesquet of the European Space Agency; and Japan’s Aki Hoshide.
$10bn James Webb Space Telescope unpacked in Kourou – BBC News
Engineers have unboxed the James Webb Space Telescope in French Guiana and will now prepare it for launch.
The $10bn successor to the Hubble observatory arrived at Europe’s Kourou spaceport five days ago after being shipped from the US.
It’s now been relieved of its transport container and raised into the vertical to allow preflight checks to begin.
JWST is one of the grand scientific projects of the 21st Century and will ride to orbit on 18 December.
An Ariane-5 rocket will throw the telescope out to an observing position about 1.5 million km from Earth.
From there, it will look deeper into the cosmos – and thus further back in time – than is possible with Hubble.
It will do this with a much bigger mirror (6.5m in diameter versus 2.4m) and instruments that are tuned to the infrared.
Scientists hope this set-up can detect the light from the very first population of stars in the Universe to switch on more than 13.5 billion years ago.
JWST is a joint venture between the US (Nasa), European (Esa) and Canadian space agencies (CSA).
It’s taken more than three decades from the original conception to get to this point.
Final assembly and testing was completed in August at the Northrop Grumman factory in Redondo Beach, California, after which the telescope was made ready for a 16-day, 2,500km journey by sea to French Guiana, a trip that took the observatory through the Panama Canal.
Teams at Europe’s spaceport will first inspect JWST to confirm no damage was picked up in transit. The telescope will then be fuelled and mated to the Ariane 5.
Recent weeks have seen cargo planes arrive in French Guiana with the tools and support equipment needed to work on Webb over the coming weeks.
A key milestone in the preparations comes this Friday when another Ariane-5 is due to launch two communications satellites from Kourou. This has to take place to free up the launch table on which Webb’s rocket will be integrated.
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