What Is a Star?

Astronomy Lecture 1:  What Is a Star?      http://video.google.com/videoplay?docid=-5550124087565365883By Professor David Helfand from Columbia University Life cycle of stars:      http://www.youtube.com/watch?v=mzE7VZMT1z8&feature=relatedHow stars are formed:         http://www.youtube.com/watch?v=_YM-SClesGI&feature=endscreen&NR=1 Life cycle of a star:           http://www.youtube.com/watch?v=u0gEaDqoH58&feature=related