Far Infrared Survey
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 (1300o 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 Clouds.
© 2002-2005 American Museum of Natural History
Last Modified: 2007-12-19 by Brian Abbott