Across
- 4. The stable phase of a star's life when it is steadily fusing hydrogen into helium in its core.
- 5. The initial stage of a star's life, when it is still gathering mass from the surrounding gas and dust.
Down
- 1. An explosion that occurs when a massive star's core collapses, releasing a tremendous amount of energy.
- 2. The remnants of a low-mass star after it has exhausted its nuclear fuel.
- 3. The most massive stars end their lives by becoming one of these, with intense gravitational forces.
- 6. The phase when a low to medium-mass star expands and cools after exhausting its hydrogen fuel.