The BBC's Watching North Korea from a supersonic fighter jet (screenshot from YouTube) shows the launch of a South Korean rocket.
I notice that it has both a very long, nicely expanded blue exhaust plume straight down as well as a large, lower velocity and wider bright yellow-white exhaust plume surrounding the top several meters of the blue one. I don't see any strap-on boosters that could account for the bright plume.
What's going on here?
In my experience rockets without SRBs come in either "blue" or "yellow/white" only
Question: What is this South Korean rocket and why does it have separate yellow and blue exhaust plumes?
screenshot from The BBC's Watching North Korea from a supersonic fighter jet