The Magellanic clouds are irregularly shaped galaxies which is an amazing feature of the Southern Hemisphere sky, visible to the naked eye. But the brightness of these dwarf galaxies combined with the fact that they occupy a large area of the night sky means that GalaxyIts neighbors block the view of many much more distant galaxies. So when astronomers observe the billions of galaxies in the universethey tend to avoid this part of the sky. “The Magellanic Clouds are beautiful galactic companions, but unfortunately they block some of our view of objects further out,” said Keele University astronomer and mapping team member Jessica Craig. a statement (opens in a new tab). “Our work helps overcome this, and in the process helps fill in the gaps in our map of the universe.” Craig and her colleagues tackled this problem by photographing the Magellanic Clouds in such high resolution that they could peer through the gaps between 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 increasingly distant “hidden” galaxies are especially hard to see because they appear fainter and redder than they are due to the dust in the Magellanic Clouds. To explain this phenomenon, 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 “reddening” these factors cause in the obscuring galaxies.
The Small Magellanic Cloud obscures galaxies in the southern hemisphere. (Image: ESA/Hubble and Digitized Sky Survey 2) Due to the sheer 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 the same position, so the team was able to use data from mapping the stars Gaia Observatory to correctly categorize each light source. Astronomers used a second technique to confirm the distinction between distant galaxies and relatively nearby stars. Because the universe is expanding as distant galaxies move away from Earth, the wavelength of light from those galaxies is stretched. The longest wavelengths of visible light are red, so astronomers call this elongation red shift. The more distant an object is, the faster it recedes, and so the redder its light appears, so distant galaxies are redder than stars. By taking color into account, the team could further eliminate stars from their data. Finally, the astronomers applied machine learning and artificial intelligence to order the galaxies and create a 3D map of about 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 United Kingdom Follow us on Twitter @Spacedotcom and up Facebook.
