Steel Wire Rusting & Glowing Orange

In my backyard I have a DIY wire trellis made in part by wrapping a steel wire around a water wellhead. I noticed out the window in the dark a tiny pinprick of orange / yellow light coming from the area, and upon closer inspection it originated from a point of contact between the trellis wire and the side of the well. The wire is 5-10 years old and rusted only around this point of contact. The glow disappeared when I disturbed the wire slightly. The outside temperature was 22°F.


Any idea what could be causing this phenomenon? I might be searching the wrong set of keywords, but I can't find anything online.


Upfront I'll say the closest I found is [this question](https://chemistry.stackexchange.com/questions/42328/why-is-my-rusting-metal-chainlink-fence-glowing-bright-orange-and-sparking). My question could perhaps be more suitable as a comment on linked question, but


1. I'm new to the stackexchange and cannot write comments
2. I'm unsure if reviving a >5yr old question is the right thing


