720 XTF Search Results (expand=subject;f1-subject=Star;f2-associated-Lesson=Gamma Ray Science);f1-subject%3DStar;f2-associated-Lesson%3DGamma%20Ray%20Science Results for your query: expand=subject;f1-subject=Star;f2-associated-Lesson=Gamma Ray Science Thu, 01 Jan 1970 12:00:00 GMT First stars. An artist's concept of the first stars forming after the Big Bang. The first stars should have been supermassive and metal poor stars that would end with a collapsar and a GRB, but there is currently no evidence of these earliest GRBs. Thu, 01 Jan 1970 12:00:00 GMT Artist’s visualization of a collapsar. The collapsing star scenario that is one of the leading contenders as the cause of gamma-ray bursts. This artist's concept of the collapsar model shows the center of a dying star collapsing minutes before the star implodes and emits a gamma-ray burst that is seen across the universe. Many scientists say longer bursts (more than four seconds in duration) are caused by massive star explosions. Thu, 01 Jan 1970 12:00:00 GMT