Astronomers have created the largest-ever 3D map of a million distant galaxies otherwise obscured by the Milky Way’s neighboring dwarf galaxies, the Magellanic Clouds.
The Magellanic Clouds are irregularly shaped galaxies which are an amazing feature of the Southern Hemisphere sky, visible to the naked eye. But the brightness of these dwarf galaxies coupled with the fact that they occupy a large part of the night sky means that the Milky WayNeighbors block our view of many much more distant galaxies. So when astronomers look at the billions of galaxies in the universethey tend to avoid this part of the sky.
“The Magellanic Clouds are beautiful galactic companions, but they unfortunately block some of our view of more distant objects,” said Jessica Craig, Keele University astronomer and member of the construction team. Cards. A declaration (opens in a new tab). “Our work helps overcome this and, in doing so, fill in the gaps in our map of the universe.”
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Craig and his colleagues tackled this problem by photographing the Magellanic Clouds in such high definition that they could look through the gaps between them. stars that make up these galaxies. To make these images, the team turned to the Visible and Infrared Survey Telescope for Astronomy (VISTA) based at the Paranal Observatory in Chile.
But these more and more distant “hidden” galaxies are particularly difficult to see because they appear fainter and redder than they are due to dust from the Magellanic Clouds. To account for this effect, the team turned to a radio telescope, the Galactic Australian Square Kilometer Array Pathfinder Survey (GASKAP), which can peer through the dust between Earth and distant galaxies. The GASKAP data allowed scientists to create a detailed map of the gas and dust in the Magellanic Clouds and thus account for the amount of “blush” these factors are causing to the galaxies they obscure.
Due to the large number of light sources in images of the Magellanic Clouds, the human eye alone cannot distinguish distant galaxies from closer objects. But stars change position while distant galaxies stay in one place, so the team was able to use star mapping data Gaia Observatory to properly categorize each light source.
Astronomers used a second technique to confirm the distinction between distant galaxies and relatively nearby stars. Because the universe expands as distant galaxies move away from Earth, the wavelength of light from these galaxies is stretched. Longer wavelengths of visible light are red, so astronomers call this elongation red shift.
The further away an object is, the faster it is moving away, and therefore the redder its light appears, so distant galaxies are redder than stars. By accounting for color, the team was able to further eliminate stars from their data.
Finally, astronomers applied machine learning and artificial intelligence to order the galaxies and create a 3D map of around 1 million galaxies.
Craig presented the team’s findings in mid-July at the National Astronomy Meeting held at the University of Warwick in the UK
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