Should one ask questions regarding some thought experiments on the Astronomy Stack Exchange? (Assuming that these thought experiments are somewhat related to astronomy/astrophysics but aren't completely scientific) ?
Astronomy is more of a hard science stack, so thought experiments are going to be, at best, right on the border of being off-topic. And it would probably need to be more than just somewhat related to astronomy/astrophysics. There are other SE sites, such as Physics and World Building. If it's more of a general physics question than it is an astronomy question, it would probably get a better answer there than here. World Building might be a good place to ask your more "out there" thought experiments.
From the help center under What questions are off topic here:
Questions that are purely hypothetical, for example a question such as 'Could a black hole destroy the universe' or 'What if our solar system had two suns' (however, feel free to visit World Building)
I think thought experiments fit this disqualification rather neatly, and I don't really see any reason to change it. Information found here should always come from a scientific perspective. If the question is not based in science or science is not applicable to the answer then there are better sites to use. In addition to the sites Donald listed, I would also suggest considering Science Fiction and Fantasy (as per the SF question we had today).
If you think such a thought experiment wouldn't fit the above disqualification, it may be helpful to provide an example of what kind of thought experiments you are thinking of.