X-ray & Optical Images of M51
Like the Milky Way, the Whirlpool is a spiral galaxy with spectacular arms of stars and dust. M51 is located about 25 million light years from Earth, and its face-on orientation to Earth gives us a perspective that we can never get of our own spiral galactic home. By studying the Whirlpool in X-ray light, astronomers can reveal things that would otherwise be invisible in other wavelengths. For example, nearly a million seconds of observing time from NASA's Chandra X-ray Observatory were used to create this new image. These data reveal over 400 X-ray sources within the galaxy. Most of these are so-called X-ray binary systems, in which a neutron star or black hole is in orbit with a star like our Sun. Understanding where these systems are, how they behave over time, and their role in the evolution of the galaxy in important is helping learn us more about other galaxies including our own.
(Credit: X-ray: NASA/CXC/Wesleyan Univ./R.Kilgard, et al; Optical: NASA/STScI)