Probably a leaky warp reactor on a passing starship :)
- Whatever Star Trek says about warp reactors (matter / antimatter reaction) is valid. Reacts "some" amount of matter/antimatter every second.
- Klingon Bird of Prey can maintain an effectively infinite cloaking time from a human observation perspective, so it can be nearby.
- Warp reactor "occasionally" leaks (1% of 1% of 1% of reactions? I dunno...) so we might actually detect something. "Slightly" imperfect shielding.
- Problem: 5E1 J for OMG Particle (people say its a proton). 1.8E14 J for 1 gram of matter / antimatter annihilation. Except: 1 Proton = 1.6726231E-24 g. Proton rest mass energy is 1.503E−10 J. So the particle is more energetic than a Proton / Antiproton annihilation event (by a lot). It's been upshifted More than 100,000,000,000 from the rest mass energy.
- It "might" work if the one proton escaping represented a single proton gaining enough energy to overcome reactor core shielding confinement, which, in my opinion, seems somewhat plausible physics by Star Trek standards.
- PS: Personal guess is a Q-Clearance [3] experiment at a DOE lab we deny exists.
[1] https://en.wikipedia.org/wiki/Orders_of_magnitude_(energy)
Robin Hanson's description of long-lived stars (usually strongest in infrared - i.e. the 3 stars our eyes lack the spectral response to see for every 1 star that we do see when looking into the night sky) significantly updated my priors on the likelihood of intelligent, non-human life roaming about the cosmos.
https://youtu.be/cQq2pKNDgIs?t=1210 (timestamped)
tl;dr: Red-dwarf stars have been around -- with all that goes with that.. -- for much, much longer than our sun.
I recently encountered a description of how Earth relies on the remnants of some interactions between stellar remnants which would have been far rarer early on, even if red dwarf stars were present for so long.