Summary: Yes, those are all ontopic here.
Here is a (non-exhaustive) list of astrophysical questions, with fairly good answers:
- Why do X-ray binaries such as GRS-1915 have active and quiet states?
- Why does the Earth have a tilt of ~23°?
- Why is our solar system "tipped" about 63° with respect to the plane of our galaxy?
- Why did Mars lose its magnetic field?
- What is the current accepted theory for the fate of hot Jupiters?
- Why is there a matter/anti-matter asymmetry in the universe? (cosmology)
- What is the current accepted theory as to why Mercury, despite its size, has a similar density to Earth?
- Why is the Sun's atmosphere (the corona) so hot?
- Two species of dark matter? (cosmology)
Plus, there are at least few people around with (or preparing) a degree in astrophysics who are able to handle this kind of questions:
- astromax
- guillochon
- Francesco Montesano
- UV-D (at least for planetary science/atmosphere)
- myself
- Manishearth (Currently an undergrad, has not yet decided a field but is leaning towards astrophysics)
- Eduardo Guerras Valera
- Freelanceastro
I did not check on everybody though.
