I'm not sure if Unity supports DX11 (bit of help here Dan?) but I don't really see the need for it to be in the game. Many low-mid range computers either don't support it or run it at a terrible FPS, whereas DX9 is much less taxing on resources and supported by every computer nowadays, no doubt. And for something like Universe Sandbox, you wouldn't notice much difference anyway...
As for the video card, I would expect not that much - as I said before it would probably be a DX9 card - Nvidia 8800 GT? And recommended at something like a GTX 260. Processor would probably be higher due to all the mathematical calculations - proabably a 2.8GHz dual-core Intel i3 or 3.0GHz quad-core AMD Phenom. Memory would need much, 2GB I suppose.
But I'll leave it to Dan for the official stuff.