Astrophysics Fundamentals Flashcards
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Read the first 6 Astrophysics Fundamentals flashcards as text
What is Olbers' paradox?
Answer: The question of why the night sky is dark if the universe is infinite, infinite in age, and uniformly filled with stars
Olbers' paradox asks why the night sky is dark if the universe is infinite and uniformly filled with stars: every line of sight should eventually hit a star, making the sky as bright as the Sun's surface.
What is the Jeans mass in star formation?
Answer: The critical mass above which a gas cloud becomes gravitationally unstable and collapses to form a star
The Jeans mass is the critical mass threshold above which a gas cloud's self-gravity overcomes thermal pressure, causing the cloud to collapse and potentially form one or more stars.
What is the concept of cosmic distance ladder?
Answer: A series of increasingly distant measurement techniques, each calibrated against the previous, for determining distances across the universe
The cosmic distance ladder is a succession of overlapping methods for measuring astronomical distances: parallax → Cepheid variables → Type Ia supernovae → Hubble flow, each calibrating the next rung.
What is the principle of equivalence in general relativity?
Answer: Gravitational mass and inertial mass are equivalent, and gravity is locally indistinguishable from acceleration
Einstein's equivalence principle states that gravitational and inertial mass are identical, meaning the effects of gravity are locally indistinguishable from those of acceleration, forming the foundation of general relativity.
What is nucleosynthesis in astrophysics?
Answer: The process by which atomic nuclei of elements heavier than hydrogen are created in stars and cosmic events
Nucleosynthesis refers to the processes that create atomic nuclei, including Big Bang nucleosynthesis (H, He, Li), stellar nucleosynthesis (elements up to iron), and explosive nucleosynthesis in supernovae (elements beyond iron).
What is the r-process in astrophysics?
Answer: Rapid neutron capture by atomic nuclei producing elements heavier than iron, occurring in neutron star mergers and supernovae
The r-process (rapid neutron capture process) creates heavy elements beyond iron by bombarding nuclei with neutrons faster than they can decay, now confirmed to occur during neutron star mergers (kilonovae).