Are these photographic artifacts of some kind and if so how would they occur? They are almost the same exact shape and size. It is a photo of the Kuiper Belt from the New Horizon space probe taken directly from NASA web site. If it is not a common photographic event then what could it be?
The LORRI CCD incorporates anti-blooming technology to eliminate bleeding of the electrons along columns when bright targets saturate (i.e., when the signal in a pixel exceeds the full-well capacity of ∼80,000 electrons).
Otherwise the tails of bright stars would be white and blocky. Figure 5, another deep image of a star field, explains similar artifacts:
The brightest stars are saturated and have black tails due to amplifier undershoot.
The analog electronics chain exhibits memory, necessitating the application of a digital filter to remove this effect, called Local Detector Electronics (LDE) undershoot.