Nitrogen oxides

During the latest Starship mission, I noticed a curious orange ring around the engine plume:

My first thought was:

• Color of nitrogen oxides but no nitrogen fuels
• High temperature exhaust plume
• Extreme plume shock waves
• Disappeared above 45 km, thiner atmosphere

Google reports:

Themal : The exhaust plumes of rocket engines (especially those burning kerosene, liquid hydrogen, or solid propellants) reach temperatures exceeding \(2000^{\circ }\text{C}\) to \(3600^{\circ }\text{C}\). At these extreme temperatures, atmospheric nitrogen (\(\text{N}_{2}\)) and oxygen (\(\text{O}_{2}\)) dissociate and recombine to form nitrogen monoxide (\(\text{NO}\)) and nitrogen dioxide (\(\text{NO}_{2}\)). [1, 2, 3]
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Bob Wilson

 

Sometimes it is easier to take a screenshot and post the image. Lessons learned, thx.

Bob Wilson