From what I understand, Aysel is normally Romanised as Ayzel for some reason, but Aysel is an accepted alternative. I have no idea why Ayzel is such a common way of Romanising it, since it sounds nothing like such a spelling would suggest. It is pronounced ai-SAYL and is indeed 'moon stream'. However this name refers figuratively to the Milky Way, and this is a more common, if assumed, meaning of the name.