11
Measurements
at other Wavelengths
•Infrared
“Cirrus”
–really
slightly warm dust
•X-Rays
of hot gas near exploded
stars (supernova)
•Radio
observations of “Molecular
Clouds”
–Called
that because cool and dense enough for molecules to form
–H2 also hard to detect
–CO
common and easy to detect
–Densest
have 1000 atoms/cm3
–T
as low as 10 K
–Location
of star formation
From our text: Horizons, by Sees