Chapter 12 — Surveying the Stars
Parsec — parallax of one arcsec; 3.26 light-years.
Proper Motion — amount a star moves across the sky; most are too far away to see proper motion.
Apparent brightness — brightness of star in the night sky.
Magnitude scale — each magnitude number changes by 2.5× up or down.
Absolute magnitude — how bright a star would appear at 10 parsecs.
Spectral classes — know spectral classes (O B A F G K M) and their temp ranges (hottest → coolest).
Mass-luminosity — the more massive the star, the brighter it is.
Radius-luminosity-temperature relationship — to truly know a star's brightness you need to know size and temperature.
HR diagram — know diagram and where hot/cool stars are, bright/dim, main sequence and white dwarfs and red giants.
Visual Binaries — can see the two stars; used to get masses.
Spectroscopic Binaries — cannot see the companions but the spectrum tells us they are there.
Spectroscopic Parallax — uses HR diagram to measure distance to stars.
Eclipsing Binaries — two stars that block each other's light; easy to measure masses of stars.
Luminosity classes — know luminosity classes (I supergiant → V main sequence).
Globular — know characteristics (old, spherical, in halo, low metals, ~100,000+ stars).
Galactic (open) — know characteristics (young, in disk, fewer stars, more metals).
Main sequence turnoff point — star leaves main sequence as it gets old; used to date clusters.
Chapter 13 — Star Stuff
Molecular clouds — large cool gas cloud with many materials and dust; site of star formation.
Protostar — forming star.
Jets — gases ejected as a star forms.
Thermal vs. degenerate pressure — thermal pushes out; degenerate stops collapse inward.
Brown dwarfs — failed stars (< 0.08 M☉).
Hydrogen shell burning — older star with fusion moved out from the core.
Helium fusion / helium flash — star trying new fuel in a flash.
White dwarf + planetary nebula — Sun dies as a core (white dwarf) surrounded by planetary nebula.
CNO cycle — more massive stars than the Sun use this fusion cycle.
Iron stage — last fuel that the most massive stars can use.
Supernova — huge explosion. Type Ia = binary white dwarf death. Type II = one large star explodes.
Neutron star — 1.4 to 6 solar masses; ~10 mile collapsed core of neutrons.
Chapter 14 — Bizarre Stellar Graveyards
Electron degeneracy — what stops a white dwarf from collapsing further.
White dwarf — 0.1 to 1.4 solar masses; Sun ends up this way; ~10,000 miles across (Earth size).
White dwarf limit — 0.1 to 1.4 (Chandrasekhar limit).
Accretion disk — material falling in; ~10 percent energy production.
Nova — binary star explosion; periodic.
White dwarf supernova — binary stars collapse on each other; Type Ia.
Massive star supernova — Type II; one large star explosion.
Neutron stars — 1.4 to 6 solar masses; ~10 mile collapsed core of neutrons.
Neutron degeneracy — stops further collapse.
Pulsars — rotating neutron stars.
Black hole — light cannot escape; 6 solar masses and above.
Schwarzschild radius — the size of a black hole's event horizon.
Event horizon — once you cross, you cannot return.
Singularity — mass but no size.
Gamma-ray bursts — matter falling into black holes giving large explosions of gammas.
Chapter 15 — Our Galaxy (Milky Way)
Parts of galaxy — disk, halo, bulge, central black hole, dark matter halo.
Spiral Density Wave — theory that the massive black hole in our galaxy sends compression waves through the galaxy and creates new spiral arms.
Interstellar medium — material between stars; gas and dust.
21 cm radiation — hydrogen spin flip; radio waves.
Dark Matter — 90 percent of matter in galaxy.
Cosmic rays — particles shot out by supernova.
Dust grains — carbon and silicate dust between stars.
Emission nebula — heated glowing gases.
Reflection nebula — bluish from dust reflection.
Molecular clouds — prime areas for formation.
Study workflow
Test 4 has the most concepts — pace yourself. Drill Flashcards filtered to U4 across multiple sessions → Practice Exam Adaptive mode → take Test 4.