Digital Universe Guide - Hayden Planetarium

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114 3. THE MILKY WAY ATLAS 3.3.23 Carbon Monoxide All-Sky Survey Group Name mwCO Reference Composite CO Survey of the Milky Way (Dame et al. 1987) Prepared by Brian Abbott (AMNH/Hayden) Labels No Files mw-CO.speck Dependencies 03-115GHz-512.sgi Wavelength 2.6 mm Frequency 115 GHz Carbon monoxide (CO) is about 10,000 times less abundant than molecular hydrogen, yet we see traces of CO via its radio signature line at 2.6 millimeters (115 GHz). Using radio telescopes, astronomers observe this portion of the radio spectrum where the atmosphere is semitransparent. The observations used to compose this image were made with the Columbia/GISS 1.2-meter telescope in New York City as well as telescopes at Cerro Tololo in Chile. CO is used to trace molecular hydrogen (H2). Normally, CO molecules would be broken apart by the ultraviolet radiation from stars. However, the CO molecules remain shielded from the harmful UV rays deep inside dense, dusty molecular clouds of hydrogen. The Orion Nebula is the best example of a nearby giant molecular cloud. The nebula sits on the edge of a much larger cloud that is invisible to us in optical light. However, the cooler atomic hydrogen and CO radiate in this region of the EM spectrum. We observe CO mainly in the Galactic plane, where most of the gas and dust are concentrated in our Galaxy and star formation occurs. If we see CO, we can expect to see new stars. CO intensity is represented by colors mapped to the intensity of the CO spectral line. The violet and blue regions are less intense and the red and white regions are of higher intensity. The survey covers the entire range in Galactic longitude but only a narrow band centered on the Galactic equator. Because CO is confined to the plane of the Galaxy, this is a reasonable range in Galactic latitude.
3.3. MILKY WAY DATA GROUPS 115 3.3.24 Far Infrared Survey Group Name mwFIR Reference IRAS Sky Survey Atlas Explanatory Supplement (Wheelock, S. L., et al. 1994) Prepared by Ryan Wyatt (AMNH/Hayden) Labels No Files mw-iras100um.speck Dependencies mw-iras100um-1024.sgi Wavelength 100 microns Frequency 3,000 GHz IRAS (InfraRed Astronomy Satellite) was launched in January 1983 and orbited 900 km above Earth, observing the infrared sky for much of that year. With its 56-centimeter (22-inch) mirror, IRAS observed in the near and far infrared at 12, 25, 60, and 100 micron wavelengths. Infrared light comes from cooler objects in the Universe: planets, comets, asteroids, cool stars, and dust in space. When astronomers talk about dust, they do not mean those pesky particles that settle on your tabletops. Astrophysical dust refers to very, very small particles. Dust was once thought to be particles composed of 10,000 atoms or more, but thanks to IRAS and other space telescopes, we now understand that it can include smaller particles of just 100 atoms. These microscopic particles are normally quite cold, close to absolute zero even, but when ultraviolet light shines on them, they can increase in temperature by 1000 Kelvin (1300 ◦ F). IRAS’s most important discovery was the extent to which dust pervades the Galaxy. IRAS provided us with the most detailed map of interstellar dust to date. Dust is created when stars explode and, therefore, is present where stars are forming. For this reason, dust is abundant within interacting galaxies where mergers trigger new stars to form. This image is in the 100-micron far infrared (FIR) survey. Astronomers consider far infrared light to be in the range of a few tens of microns to about 300 microns. This corresponds to objects with temperatures of about 15 Kelvin to about 120 Kelvin and includes cold dust particles and cold molecular clouds. In some of these clouds, new stars are forming and glow in FIR light. The center of our Galaxy glows brightly in FIR light, where dense clouds of dust are heated by the stars within them. This results in the bright band of light toward Galactic center. The survey is rich in detail, with bright glows in areas of star formation, like the Orion complex and Rho Ophiuchi. Bright extragalactic sources can be seen too, like the Andromeda Galaxy and the Small and Large Magellanic
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The Digital Universe Guide Brian Ab
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Contents Contents 3 List of Tables
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List of Tables 2.1 Log and Linear F
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1.2. GETTING HELP 7 1.2 Getting Hel
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1.5. ACKNOWLEDGMENTS 9 1.5 Acknowle
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2.2. LAUNCHING THE MILKY WAY ATLAS
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2.3. LEARNING TO FLY PARTIVIEW 13 T
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2.3. LEARNING TO FLY PARTIVIEW 15 M
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2.4. PARTIVIEW’S USER INTERFACE 1
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2.5. DIGITAL UNIVERSE FILES 23 File
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3.1. MILKY WAY ATLAS OVERVIEW 25 3.
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3.2. MILKY WAY ATLAS TUTORIAL 27 3.
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3.2. MILKY WAY ATLAS TUTORIAL 29 Wi
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3.2. MILKY WAY ATLAS TUTORIAL 31 Yo
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3.2. MILKY WAY ATLAS TUTORIAL 33 th
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3.2. MILKY WAY ATLAS TUTORIAL 35 Op
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3.2. MILKY WAY ATLAS TUTORIAL 39 co
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3.2. MILKY WAY ATLAS TUTORIAL 41 li
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3.2. MILKY WAY ATLAS TUTORIAL 45 In
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3.2. MILKY WAY ATLAS TUTORIAL 47 No
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3.2. MILKY WAY ATLAS TUTORIAL 49 Th
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3.2. MILKY WAY ATLAS TUTORIAL 51 to
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3.2. MILKY WAY ATLAS TUTORIAL 53 st
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3.2. MILKY WAY ATLAS TUTORIAL 55 th
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3.2. MILKY WAY ATLAS TUTORIAL 57 bi
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3.2. MILKY WAY ATLAS TUTORIAL 59 in
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Page 145 and 146: 4 The Extragalactic Atlas The word
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4.2. EXTRAGALACTIC ATLAS TUTORIAL 1
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4.2. EXTRAGALACTIC ATLAS TUTORIAL 1
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4.3. EXTRAGALACTIC DATA GROUPS 169
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4.4. OPTIMIZING THE EXTRAGALACTIC A
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Appendix A Light-Travel Time and Di
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Appendix B Parallax and Distance On
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absolute magnitude M, can be calcul
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discovered that there was a linear
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Appendix D Electromagnetic Spectrum
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Appendix E Constants and Units In a
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Metric Prefixes These prefixes are
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INDEX 221 center command, 50, 61 cl
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INDEX 223 Earth’s radio signals,
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INDEX 225 irregular galaxy, 147, 17
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INDEX 227 entering, 21 every, 206 j
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INDEX 229 stellar distance uncertai
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