June 4, 2013

Image Credit: NASA / Axel Mellinger, Central Michigan University

April Flowers for redOrbit.com Your Universe Online

Using NASAs Swift satellite, astronomers from NASA and Pennsylvania State University have created the most detailed ultraviolet surveys to-date of the two closest major galaxies, the Large and Small Magellanic Clouds.

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, said Stefan Immler. Immler originally proposed the program and led NASAs contribution from the Goddard Space Flight Center.

At the 222nd American Astronomical Society meeting this week, Immler presented a 160-megapixel mosaic image of the Large Magellanic Cloud (LMC) and a 57-megapixel mosaic image of the Small Magellanic Cloud (SMC). These images reveal approximately one million ultraviolet sources in the LMC and another 250,000 in the SMC. Light ranging from 1,600 to 3,300 angstroms, which is a range of UV wavelengths largely blocked by Earths atmosphere, was included in the images as well.

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 Swifts Ultraviolet/Optical Telescope (UVOT) at the Swift Mission Operations Center.

The LMC lies approximately 163,000 light-years from Earth, while the SMC is about 200,000 light-years away. They orbit each other, as well as orbiting our Milky Way galaxy, and are both smaller than our own galaxy. The LMC is one-tenth the size, containing only one percent of the mass of the Milky Way. The SMC, on the other hand, is half the size and contains two-thirds the mass.

Because they are so close to us, relatively speaking, both galaxies loom large in our sky and extend far beyond the UVOTs field of view. Thousands of images were needed in order to cover both galaxies in three ultraviolet colors centered at wavelengths of 1,928 angstroms, 2,246 angstroms, and 2,600 angstroms.

Astronomers were able to suppress the light of normal stars like our Sun by viewing in the ultraviolet wavelength. These stars are not very bright at such higher energies, allowing the ultraviolet to provide a clearer picture of the hottest stars and star-formation regions. UVOT is the only telescope currently able to produce such high-resolution, wide-field multicolor surveys in the ultraviolet range. The wide-field imaging capabilitiesof the Swift satellite provide a powerful complement to the deeper, but much narrower-field imaging power of NASAs Hubble Space Telescope.

Continued here:

NASA’s Swift Maps Magellanic Clouds With Ultraviolet