Birth of a Supernova Type 1a Page 1 of 6 | Next page Type Ia supernovae originate in binary star systems -- systems where two stars orbit each other. In one possible scenario, there are two stars approximately the same size -- let's say about the size of our sun. At a certain point in their lifetimes, each star will expand into a red giant, then turn into a white dwarf. Next page History of the Universe | Birth of a Supernova | Tour the Universe Moving Targets | How Big is the Universe? | Spin a Spiral Galaxy Resources | Transcript | Site Map | Runaway Universe Home Editor's Picks | Previous Sites | Join Us/E-mail | TV/Web Schedule About NOVA | Teachers | Site Map | Shop | Jobs | Search | To print PBS Online | NOVA Online | WGBH © | Updated December 2000