Stars and Galaxies

117 flashcards by MentisLibrary

Stellar physics from fusion and the H-R diagram to white dwarfs, neutron stars and supernovae, then galaxy types, clusters, dark matter, active galactic nuclei and the cosmic distance ladder, for introductory astronomy students.

What is a star?: Self-luminous sphere of plasma
What is the Sun's spectral class?: G2V
What is the Sun's mass?: ≈ 2 × 10³⁰ kg
What is the Sun's radius?: ≈ 696000 km
What is the Sun's luminosity?: ≈ 3.8 × 10²⁶ W
What is the Sun's composition?: ≈ 73% hydrogen 25% helium 2% heavier elements
What is nuclear fusion in stars?: Hydrogen fuses into helium
What is the proton-proton chain?: Main fusion process in Sun-like stars
What is the CNO cycle?: Fusion using carbon nitrogen oxygen as catalysts
What is stellar parallax?: Apparent shift in star position due to Earth's orbit
What is a parsec?: Distance at which 1 AU subtends 1 arcsecond
What is a light-year?: Distance light travels in one year
What is absolute magnitude?: Brightness at standard distance of 10 parsecs
What is apparent magnitude?: Brightness as seen from Earth
What is the distance modulus?: m - M = 5 log₁₀(d/10)
What is the Hertzsprung-Russell diagram?: Plot of luminosity vs temperature
What is the main sequence?: Diagonal band on H-R diagram
What is a red giant?: Large cool evolved star
What is a white dwarf?: Dense remnant of low-mass star
What is a neutron star?: Ultra-dense remnant of massive star
What is a black hole?: Region where gravity prevents escape
What is a supernova?: Explosive death of massive star
What is a supernova remnant?: Expanding shell of debris
What is stellar nucleosynthesis?: Formation of heavier elements in stars
What elements are formed in supernovae?: Elements heavier than iron
What is the Chandrasekhar limit?: Maximum mass of white dwarf ≈ 1.4 solar masses
What is the Tolman-Oppenheimer-Volkoff limit?: Maximum mass of neutron star ≈ 2-3 solar masses
What is a pulsar?: Rotating neutron star with beamed radiation
What is the Crab Pulsar?: Pulsar in Crab Nebula
What is stellar mass?: Measured in solar masses (M)