Life Cycle of a Star Flashcards

Life Cycle of a Star

• All stars originate from a nebula, which is a vast cloud composed of gas and dust.
• A protostar forms when gravity pulls together portions of the gas and dust within a nebula.
• The process of star formation begins when the temperature and pressure in a protostar increase sufficiently to trigger nuclear fusion.
• A star shines when hydrogen atoms fuse together, releasing enormous energy.
• As a main sequence star exhausts its hydrogen fuel, it will expand into a red giant or red supergiant.

Stages of a Star's Life

• Stars begin as diffused clouds of gas and dust known as nebulae, where the initial formation occurs.
• Gravity causes the nebula to collapse into denser clumps, leading to the protostar stage.
• During protostar formation, heat and pressure culminate in nuclear fusion, marking the start of a star's lifecycle.
• When fusion ignites, the star becomes luminous and enters the main sequence phase of its life.
• The subsequent transformation into a red giant or red supergiant depends on the star's available fuel and mass.

End Stages of a Star

• A white dwarf forms as the remnant core left when a medium-mass star sheds its outer layers in a planetary nebula.
• A supernova occurs when a red supergiant star reaches the end of its fusion processes and undergoes a catastrophic explosion.
• The remnants of high-mass stars result in neutron stars, which are extremely dense.
• A medium-mass star eventually becomes a black dwarf when it has cooled and ceased nuclear fusion.
• Black holes represent the end state of massive stars, characterized by an intense gravitational pull that prevents light from escaping.

Additional Terms

• Nebula: A large gas and dust cloud in space where stars form.
• Protostar: The earliest stage in the lifecycle of a star before nuclear fusion starts.
• Supernova: An explosive death of a star, often leading to a neutron star or black hole formation.
• Neutron Star: The dense remains of high-mass stars after a supernova explosion.
• Black Dwarf: The final state of a medium-mass star at the conclusion of its life cycle.
• Black Hole: An astronomical entity with a gravitational field so strong that not even light can escape its pull.