Right now, all astronomy is done through the School of Physics. Here is everything they cover:
1st year- you can do the PHYS1500 Astronomy course. It is interesting, easy, and fun, but not very rigorous (has no maths at all, in fact). Its main role seems to be to attract interested students and to serve as "filler" if you need more credit points. You do not need this course for anything, and it is not a prerequisite for any other course.
2nd year- the optional elective PHYS2013/PHYS2913 Astrophysics and Relativity course does a bit on stellar astrophysics. It is actually pretty dry, but is recommended for any propsective physics major.
3rd year- there is an astronomy module.
4th year and beyond- you can do your honours/PhD with the astronomy department within the School of Physics.
You cannot major in astronomy at this time, but you can specialise in astronomy at the honours level.