by Chris Peterson » Sat Jan 31, 2015 4:01 pm
The complexity of what we're seeing in this image isn't really made fully clear by the caption. First of all, we're looking at data collected with two completely different instruments- the two shorter wavelength bands with the IRAC camera, and the long wavelength band with the MIPS camera. All of the data is rather broadband- the 3.6 μm band covers 3-4 μm, the 8 μm band covers 6.4-9.3 μm, and the 24 μm band covers 20-30 μm. That means these sensors are detecting a lot of low temperature thermal blackbody emissions from dust and gas. But in regions like this, you have PAHs, which are hydrocarbon molecules which fluoresce in two of the IRAC band (5.8 μm and 8 μm). Only the 8 μm band is included in today's image, so actually separating PAH emissions from thermal emissions might be tricky. But still, there's a lot going on here.
The complexity of what we're seeing in this image isn't really made fully clear by the caption. First of all, we're looking at data collected with two completely different instruments- the two shorter wavelength bands with the IRAC camera, and the long wavelength band with the MIPS camera. All of the data is rather broadband- the 3.6 μm band covers 3-4 μm, the 8 μm band covers 6.4-9.3 μm, and the 24 μm band covers 20-30 μm. That means these sensors are detecting a lot of low temperature thermal blackbody emissions from dust and gas. But in regions like this, you have PAHs, which are hydrocarbon molecules which fluoresce in two of the IRAC band (5.8 μm and 8 μm). Only the 8 μm band is included in today's image, so actually separating PAH emissions from thermal emissions might be tricky. But still, there's a lot going on here.