Visualization of the Radcliffe Wave: a massive, wave-shaped gaseous structure made up of stellar nurseries, forming one of the largest coherent structures ever observed in our galaxy. This image, taken from the World Wide Telescope, represents the study data overlaid on an artist’s illustration of the Milky Way and our sun. Credit: Alyssa Goodman / Harvard University
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.”
“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 Harvard Professor Alyssa Goodman (left), standing with graduate student Catherine Zucker, a key member of the team. Credit: Kris Snibbe/Harvard Staff Photographer
“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.
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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.
References:
“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. DOI: 10.1038/s41586-019-1874-z
“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. DOI: 10.3847/1538-4357/ab5362
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.
NAIROBI, Kenya (AP) — The body of Ugandan Olympic athlete Rebecca Cheptegei — who died after being set on fire by her partner in Kenya — was received Friday by family and anti-femicide crusaders, ahead of her burial a day later.
Cheptegei’s family met with dozens of activists Friday who had marched to the Moi Teaching and Referral Hospital’s morgue in the western city of Eldoret while chanting anti-femicide slogans.
She is the fourth female athlete to have been killed by her partner in Kenya in yet another case of gender-based violence in recent years.
Viola Cheptoo, the founder of Tirop Angels – an organization that was formed in honor of athlete Agnes Tirop, who was stabbed to death in 2021, said stakeholders need to ensure this is the last death of an athlete due to gender-based violence.
“We are here to say that enough is enough, we are tired of burying our sisters due to GBV,” she said.
It was a somber mood at the morgue as athletes and family members viewed Cheptegei’s body which sustained 80% of burns after she was doused with gasoline by her partner Dickson Ndiema. Ndiema sustained 30% burns on his body and later succumbed.
Ndiema and Cheptegei were said to have quarreled over a piece of land that the athlete bought in Kenya, according to a report filed by the local chief.
Cheptegei competed in the women’s marathon at the Paris Olympics less than a month before the attack. She finished in 44th place.
Cheptegei’s father, Joseph, said that the body will make a brief stop at their home in the Endebess area before proceeding to Bukwo in eastern Uganda for a night vigil and burial on Saturday.
“We are in the final part of giving my daughter the last respect,” a visibly distraught Joseph said.
He told reporters last week that Ndiema was stalking and threatening Cheptegei and the family had informed police.
Four in 10 women or an estimated 41% of dating or married Kenyan women have experienced physical or sexual violence perpetrated by their current or most recent partner, according to the Kenya Demographic and Health Survey 2022.
TEL AVIV, Israel (AP) — A rare Bronze-Era jar accidentally smashed by a 4-year-old visiting a museum was back on display Wednesday after restoration experts were able to carefully piece the artifact back together.
Last month, a family from northern Israel was visiting the museum when their youngest son tipped over the jar, which smashed into pieces.
Alex Geller, the boy’s father, said his son — the youngest of three — is exceptionally curious, and that the moment he heard the crash, “please let that not be my child” was the first thought that raced through his head.
The jar has been on display at the Hecht Museum in Haifa for 35 years. It was one of the only containers of its size and from that period still complete when it was discovered.
The Bronze Age jar is one of many artifacts exhibited out in the open, part of the Hecht Museum’s vision of letting visitors explore history without glass barriers, said Inbal Rivlin, the director of the museum, which is associated with Haifa University in northern Israel.
It was likely used to hold wine or oil, and dates back to between 2200 and 1500 B.C.
Rivlin and the museum decided to turn the moment, which captured international attention, into a teaching moment, inviting the Geller family back for a special visit and hands-on activity to illustrate the restoration process.
Rivlin added that the incident provided a welcome distraction from the ongoing war in Gaza. “Well, he’s just a kid. So I think that somehow it touches the heart of the people in Israel and around the world,“ said Rivlin.
Roee Shafir, a restoration expert at the museum, said the repairs would be fairly simple, as the pieces were from a single, complete jar. Archaeologists often face the more daunting task of sifting through piles of shards from multiple objects and trying to piece them together.
Experts used 3D technology, hi-resolution videos, and special glue to painstakingly reconstruct the large jar.
Less than two weeks after it broke, the jar went back on display at the museum. The gluing process left small hairline cracks, and a few pieces are missing, but the jar’s impressive size remains.
The only noticeable difference in the exhibit was a new sign reading “please don’t touch.”
VICTORIA – The British Columbia government is partnering with a bear welfare group to reduce the number of bears being euthanized in the province.
Nicholas Scapillati, executive director of Grizzly Bear Foundation, said Monday that it comes after months-long discussions with the province on how to protect bears, with the goal to give the animals a “better and second chance at life in the wild.”
Scapillati said what’s exciting about the project is that the government is open to working with outside experts and the public.
“So, they’ll be working through Indigenous knowledge and scientific understanding, bringing in the latest techniques and training expertise from leading experts,” he said in an interview.
B.C. government data show conservation officers destroyed 603 black bears and 23 grizzly bears in 2023, while 154 black bears were killed by officers in the first six months of this year.
Scapillati said the group will publish a report with recommendations by next spring, while an independent oversight committee will be set up to review all bear encounters with conservation officers to provide advice to the government.
Environment Minister George Heyman said in a statement that they are looking for new ways to ensure conservation officers “have the trust of the communities they serve,” and the panel will make recommendations to enhance officer training and improve policies.
Lesley Fox, with the wildlife protection group The Fur-Bearers, said they’ve been calling for such a committee for decades.
“This move demonstrates the government is listening,” said Fox. “I suspect, because of the impending election, their listening skills are potentially a little sharper than they normally are.”
Fox said the partnership came from “a place of long frustration” as provincial conservation officers kill more than 500 black bears every year on average, and the public is “no longer tolerating this kind of approach.”
“I think that the conservation officer service and the B.C. government are aware they need to change, and certainly the public has been asking for it,” said Fox.
Fox said there’s a lot of optimism about the new partnership, but, as with any government, there will likely be a lot of red tape to get through.
“I think speed is going to be important, whether or not the committee has the ability to make change and make change relatively quickly without having to study an issue to death, ” said Fox.
This report by The Canadian Press was first published Sept. 9, 2024.
