A Galaxy Revealed in Multiple Wavelengths 0 Topic: Multiwavelength observations Concepts: Infrared observations, X-ray observations, Optical observations, EM spectrum Missions: “Great Observatories”: Hubble, Chandra, Spitzer; GALEX Coordinated by the NASA Astrophysics Forum An Instructor’s Guide for using the slide sets is available at the ASP website ducation/resources-for-the- higher-education-audience/

The Four Space Observatories Provide New Insights into M101 Messier 101 (M101) is a face-on spiral galaxy 22 million light years distant in the direction of the constellation Ursa Major and is 70% larger than our own Milky Way. In 2012, GALEX ultraviolet observations added new insights into the structure of the Pinwheel Galaxy, M101. Combined with previous Spitzer, Hubble, and Chandra observations, they produced a new multiwavelength view of the galaxy M101 combining infrared, visible, ultraviolet, and X-ray images, respectively, into a single picture. Credit: NASA/CXC/SAO, NASA/JPL- Caltech, NASA/STScI 1

How do Astronomers Learn More about M101? Investigations across multiple wavelengths provides a more complete view of galaxies like M101: 2 Spitzer’s infrared view can show lanes of dust that congeal into stars—the brightest areas warmed by young, hot stars. Hubble’s visible light view can reveal a galaxy’s stars and star clusters, and brownish dust lanes silhouetted against their glow. GALEX’s ultraviolet view can locate hot, young stars that formed about 1 million years ago. Chandra’s X-ray view can unveil the emission from supernova remnants, diffuse hot gas, and regions where gas spiraling into black holes is heated to extremes.

The Big Picture Galaxies are made of various objects that emit in different wavelengths: Types of stars: young and old, big and small Diffuse gas Interstellar dust Exotic, high-energetic objects (e.g. black holes or neutron stars) A complete understanding of how galaxies form and evolve with time, requires understanding all of these components Some of them must be studied at different wavelengths. 3 Spitzer Image: Large Magellanic Cloud Chandra Image: Centaurus A Hubble Image : M51 These three galaxies have been studied extensively in various wavelengths to help astronomers better understand their evolutions.

How Does this Change our View? Adding the GALEX UV view of M101 reveals the true extent of the galaxy and shows us how many young, hot stars have recently formed in the outskirts of the galaxy’s disk! Images taken in different wavelengths reveal different aspects and processes of galaxies like M101 and of the universe at large, allowing us to build a complete picture and understanding of the cosmos. NASA’s science missions range across the electromagnetic spectrum to reveal this larger, deeper, and more fundamental view. 4 Infrared Visible UltravioletX-rayComposite Animated slide: click through to compare the images. Credit : NASA/CXC/SAO, NASA/JPL-Caltech, NASA/STScI

Resources Press release: Activities: Hubble’s Composite Images Multimedia: Video – combining the Hubble, Chandra, and Spitzer observations: EM spectrum tour: 5

A Galaxy Revealed in Multiple Wavelengths BONUS CONTENT 6

NASA leverages the EM Spectrum NASA has a fleet of telescopes that cover the electromagnetic (EM) spectrum, in order to observe the universe in different wavelengths. Because Earth’s atmosphere blocks certain wavelengths of light, space-based (and stratospheric) observatories often complement the work of ground-based observatories. 7 Credit : Goddard Space Flight Center

What do the Colors Mean? Because human eyes cannot see in Infrared, Ultraviolet, or X- ray, scientists assigned red, yellow, blue, and purple colors to Spitzer, Hubble, GALEX, and Chandra images, respectively. Combining the four colors produces the final multiwavelength image that traces various astrophysical processes occurring in the M101 galaxy. 8 Infrared Visible UltravioletX-ray Chandra GALEX HubbleSpitzer