Stellar Astronomy and Star Life Cycles Flashcards
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Read the first 6 Stellar Astronomy and Star Life Cycles flashcards as text
What is the Kelvin-Helmholtz mechanism?
Answer: Gravitational contraction that converts potential energy into thermal energy in stars
The Kelvin-Helmholtz mechanism describes how a star generates heat through gravitational contraction, converting gravitational potential energy to thermal energy, relevant during stellar formation before fusion begins.
What is a T Tauri star?
Answer: A young pre-main-sequence star still contracting toward the main sequence
T Tauri stars are young stellar objects (less than ~10 million years old) that are still gravitationally contracting before reaching the main sequence and beginning stable hydrogen fusion.
What is the Hayashi track on the H-R diagram?
Answer: The nearly vertical evolutionary path of a protostar contracting toward the main sequence
The Hayashi track is the nearly vertical path on the H-R diagram followed by a fully convective protostar as it contracts toward the main sequence at nearly constant surface temperature.
What determines where a star will fall on the main sequence?
Answer: Its mass
A star's position on the main sequence is primarily determined by its mass, as mass controls core pressure, temperature, and the rate of nuclear fusion, thus setting luminosity and surface temperature.
What is an asymptotic giant branch (AGB) star?
Answer: A late-stage giant star fusing helium in a shell around an inert carbon-oxygen core
AGB stars are late-stage evolved stars of low to intermediate mass that have exhausted core helium burning and now fuse hydrogen and helium in shells around an inert carbon-oxygen core.
What is the proton-proton chain reaction?
Answer: The primary nuclear fusion sequence in the Sun converting four protons into a helium nucleus
The proton-proton (p-p) chain is the dominant fusion process in the Sun and lower-mass stars, converting four hydrogen nuclei (protons) into one helium-4 nucleus with the release of energy, positrons, and neutrinos.