Stellar Lives

1. The element created as a direct byproduct of hydrogen fusion during the longest stage of a star's life.
2. Red ________: The swollen, cooler, and highly luminous late-life stage of a low-mass star after its core hydrogen is depleted.
5. ________ cycle: The faster chain of nuclear reactions that high-mass stars use to fuse hydrogen into helium using carbon, nitrogen, and oxygen as catalysts.
7. Planetary ________: The expanding, glowing shell of gas ejected into space by a dying low-mass star.
8. Main ________: The longest life stage of a star, during which it is stably fusing hydrogen in its core.
9. ________ dwarf: A "failed star" that did not accumulate enough mass to ever ignite sustained nuclear fusion in its core.
15. Gravitational ________: The delicate balance between the inward pull of gravity and the outward push of thermal pressure in a star.
17. The catastrophic, brilliant explosion that marks the violent death of a high-mass star.
18. The nuclear process that powers a star by combining lighter atomic nuclei into heavier ones.
20. White ________: The small, incredibly dense, glowing ember of a core left behind after a low-mass star like our Sun dies.

1. The primary element that a star spends the vast majority of its life burning in its core.
3. The chemical element that cannot yield energy through nuclear fusion, ultimately triggering the collapse of a high-mass star.
4. Helium ________: The sudden, dramatic ignition of helium fusion that occurs in the dense core of a low-mass red giant.
5. Star ________: A grouping of stars that formed at around the same time from the same interstellar cloud.
6. ________ cluster: A dense, spherical, and gravitationally bound collection of hundreds of thousands of very old stars.
10. ________ cluster: A relatively loose and irregular grouping of a few hundred to a few thousand typically younger stars.
11. The fundamental property of a star that strictly dictates its entire life cycle and ultimate fate.
12. ________ point: The specific location on an H-R diagram where a cluster's stars diverge from the main sequence, used to determine the cluster's age.
13. A forming star that has not yet reached the core temperature necessary to begin hydrogen fusion.
14. Molecular ________: The cold, dense, and dusty regions of interstellar space where new stars are born.
16. ________ hole: An object whose gravity is so immense that not even light can escape, forming from the collapse of the most massive stars.
19. ________ star: The ultra-dense, city-sized remnant left behind after a high-mass star explodes as a supernova.