A combined X-ray and infrared image of the W51 molecular cloud.
X-ray: NASA/CXC/PSU/L. Townsley et al; Infrared: NASA/JPL-Caltech
Giant molecular clouds are vast cosmic objects, composed primarily of hydrogen molecules and helium atoms, where new stars and planets are born. These clouds can contain more mass than a million suns, and stretch across hundreds of light years.
The giant molecular cloud known as W51 is one of the closest to Earth at a distance of about 17,000 light years. Because of its relative proximity, W51 provides astronomers with an excellent opportunity to study how stars are forming in our Milky Way galaxy.
The new composite image of W51 above shows the high-energy output from this stellar nursery, where X-rays from the Chandra X-ray Observatory are colored blue. In about 20 hours of Chandra exposure time, more than 600 young stars were detected as point-like X-ray sources, and diffuse X-ray emission from interstellar gas with a temperature of a million degrees or more was also observed. Infrared light observed with NASA’s Spitzer Space Telescope appears orange and yellow-green and shows cool gas and stars surrounded by disks of cool material.