Scientists Compose Most Detailed UV Maps of Small and Large Magellanic Clouds Ever Created

Astronomers at NASA and Pennsylvania State University have teamed up to create the most detailed ultraviolet light surveys ever made of the Large and Small Magellanic Clouds.

Stefan Immler of the agency’s Goddard Space Flight Center was the one who proposed the program and later presented a 160-megapixel moasaic image of the Large Magellanic Cloud (LMC) and a 57-megapixel mosaic image of the Small Magellanic Cloud (SMC) at the 222nd American Astronomical meeting on June 3.

"We took thousands of images and assembled them into seamless portraits of the main body of each galaxy, resulting in the highest-resolution surveys of the Magellanic Clouds at ultraviolet wavelengths," Immler explained in a news release.

The new images reveal approximately 1 million ultraviolet sources in the LMC and about a quarter of that in the SMC and include light ranging from 1,600 to 3,300 angstroms, the range of UV wavelengths largely blocked by Earth's atmosphere.

"Prior to these images, there were relatively few UV observations of these galaxies, and none at high resolution across such wide areas, so this project fills in a major missing piece of the scientific puzzle," said Michael Siegel, lead scientist for Swift's Ultraviolet/Optical Telescope at the Swift Mission Operations Center.

Both galaxies are much smaller than the one in which the solar system resides, with the LMC measuring about one-tenth the size of the Milky Way and only 1 percent of its mass. Meanwhile the SMC is half the size of the LMC and contains about two-thirds of its mass.

However, despite these modest sizes, both appear large in the sky due to their proximity: the LMC and SMC lie some 163,000 and 200,000 light-years away, respectively, in their orbits around each other as well as the Milky Way.

By viewing the galaxies in ultraviolet, astronomers are able to suppress the light of normal stars like the Sun, which are not very bright at such high energies, and produce a clearer picture of the hottest stars and star-formation regions.

Much more than pretty pictures for coffee table books, Immler explained that the images may yet offer insight into the mysteries of the universe.

“With these mosaics, we can study how stars are born and evolve across each galaxy in a single view, something that’s very difficult to accomplish for our own galaxy because of our location inside it,” he said.