Here is a (non-exhaustive) list of astrophysical questions, with fairly good answers:

* http://astronomy.stackexchange.com/questions/528/why-do-x-ray-binaries-such-as-grs-1915-have-active-and-quiet-states
* http://astronomy.stackexchange.com/questions/537/why-does-the-earth-have-a-tilt-of-23
* http://astronomy.stackexchange.com/questions/546/why-is-our-solar-system-tipped-about-63-with-respect-to-the-plane-of-our-gala
* http://astronomy.stackexchange.com/questions/501/why-did-mars-lose-its-magnetic-field
* http://astronomy.stackexchange.com/questions/401/what-is-the-current-accepted-theory-for-the-fate-of-hot-jupiters
* http://astronomy.stackexchange.com/questions/381/why-is-there-a-matter-anti-matter-asymmetry-in-the-universe (cosmology)
* http://astronomy.stackexchange.com/questions/362/what-is-the-current-accepted-theory-as-to-why-mercury-despite-its-size-has-a-s
* http://astronomy.stackexchange.com/questions/247/why-is-the-suns-atmosphere-the-corona-so-hot

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](http://astronomy.stackexchange.com/users/45/astromax)
* [guillochon](http://astronomy.stackexchange.com/users/2/guillochon)
* [Francesco Montesano](http://astronomy.stackexchange.com/users/86/francesco-montesano)
* [UV-D](http://astronomy.stackexchange.com/users/8/uv-d) (at least for planetary science/atmosphere)
* myself

I did not check on everybody though.