The brightness and color of the extremely bright light produced by the Space Shuttle SRB's is discussed in this answer and in comments below it, though the main subject there is the dim blue light produced by LOX/LH2.
What physical process produces the radiation that makes the Shuttle's SRB exhaust so incredibly bright? Is it still blackbody radiation from particles, though they are partly aluminum based now, or is it more due to luminescence from other molecules in the exhaust?
Does the oxidant for the aluminum contain oxygen? Are there glass "soot" particles in the exhaust?
Or is there just a lot of carbon-based soot that's also produced, but the bump in temperature from the aluminum oxidation makes it so much hotter that it's so much brighter?
There is some related discussion at the question How do rocket propellant combinations rank in terms of “brightness”? as well, which currently has no accepted answer.