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Unformatted text preview: 1 Extraterrestrial Life: Spring 2008 Orion with Hubble Space Telescope Extraterrestrial Life: Spring 2008 Disk size: at the distance of Orion (about 1500 light years) Hubble s resolution (~1 pixel) is about 50 AU This disk is ~few hundred AU in radius - much larger than the Solar System Smaller disks would not be directly detectable at this distance - selection effect Extraterrestrial Life: Spring 2008 Properties of protoplanetary disks Detect emission from hot (T~1000K) dust in the infrared (wavelengths of light longer than visible) Detect molecules such as CO and ammonia from the gas in the disk Detect cool dust (T = 10 - 100 K) via radio emission at mm wavelengths Disks contain both gas and dust. Do not directly detect larger solid bodies (rocks / asteroids / planets) Extraterrestrial Life: Spring 2008 Disk mass Can estimate the mass of dust from strength of the radio emission Typical disks have total masses (gas + dust) between 0.1 Solar masses and 10-3 Solar masses, of which 99% is gas and 1% solid material Mass of dust = 0.01 x 0.01 x 2 x 10 30 kg = 2 x 10...
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- Spring '08