How hot do you think black objects in space get? Something like 10°C. Look up thermal equilibrium of an ideal black body.
In the vicinity of the Earth, they get to about the temperature of the Earth. That’s not a coincidence. Hotter if they are actively generating heat.
But are they doing work internally that generates heat? Genuine question.
In the vicinity of the Earth, they get to about the temperature of the Earth. That’s not a coincidence. Hotter if they are actively generating heat.