Map of Milky Way Galaxy reveals presence of stellar nurseries wave
Washington D.C. [USA], Jan 8 : Astronomers from Harvard University have found the presence of a wave-shaped gaseous structure named ‘Radcliffe Wave’ in the Milky Way Galaxy.
According to the research which has been published in the journal – Nature – the wave structure is the largest ever seen in the galaxy and is made up of interconnected stellar nurseries.
This discovery by the university transforms the 150-year-old vision of the nearby stellar nurseries as an expanding ring in one featuring a star-forming filament that reached trillions of miles below and above the galactic disk.
The study was enabled through a relatively new analysis of data from the European Space Agency’s Gaia spacecraft which was launched in 2013 along with the mission of precisely measuring the distance, position, and motion of the stars.
The researchers combined the data from Gaia which was super-accurate, with other measurements for constructing a detailed, 3D map of interstellar matter in the Milky Way, and noticed an unexpected pattern in the spiral arm which is closest to the Earth.
The researchers further discovered a thin, long structure, about 9,000 light-years long and 400 light-years wide, having a shape that of a wave, cresting 500 light-years above and below the mid-plane of our galaxy’s disk.
The wave consists of stellar nurseries that have been previously thought to form a part of the ‘Gould’s Belt’, which is a band of star-forming regions and is believed to have an orientation around the Sun in a circular or ring-like fashion.
“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 the researcher, Alyssa Goodman.
“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,” Goodman added.
“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 another researcher, Joao Alves.
“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,” Alves added.
The newly developed three-dimensional map shows Earth’s galactic neighborhood in a new light, which gives researchers a revised view of the Milky Way and is also opening the door to some of the 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,” Alves added.
A long-standing challenge for astronomy and astronomers is disentangling structures that are present in the ‘dusty’ galactic neighbourhood. In previous studies, a group of researchers mapped the three-dimensional distribution of dust using a vast survey of stars.
Using the new data researchers recently augmented these techniques, which dramatically improves the ability of astronomers for measuring the distances to star-forming regions. The work which was led by the researcher Zucker has been 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,” said Zucker.
“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 added.
“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,” another researcher Finkbeiner said.
Agreeing to the claims by Zucker and Finkbeiner, Goodman said, “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.”