Astronomy Test 4
Radar Ranging
Cosmetic Distance Ladder: Solar System
Parallax
Cosmetic Distance Ladder: Nearby Stars
Main-Sequence Fitting
Cosmetic Distance Ladder: Milky Way
Cepheids
Cosmetic Distance Ladder: Nearby Galaxies
Distant Standards
Cosmetic Distance Ladder: Galaxy Clusters
10^-4
Distance: Solar System
10^2
Distance: Nearby Stars
10^5
Distance: Milky Way
10^7
Distance: Nearby Galaxies
10^10
Distance: Galaxy Clusters
Planck Epoch
Mystery partly because we lack a quantum theory of gravity
The Grand Unification Epoch
Forces except gravity are unified
The Inflationary Epoch
Universe expands rapidly smaller than a proton to bigger than a melon
Electroweak Epoch
Weak and electromagnetic forces act as one
The Quark, Hadron, and Lepton Epoch
What we think of a “normal” elementary particle form and survive
Photons, Nucleosynthesis, and the Cosmic Background Radiation
Atoms form (Hydrogen and Helium) and Cosmic Background radiation ‘decouple’ from matter
Dark Ages
Atoms exists but stars don’t
“Modern” Era
Stars form; Quantum fluctuations at the time of inflation determines the distribution of matter in the universe. Denser areas are where stars will form. Gravity is the major large-scale force.
100,000 light years across, 1000 light years deep
Milky Way: Size
200 Billion Stars
Milky Way: Number of Stars
In the disk; 2/3 of the way out from the center
Milky Way: Location of the Sun
Bulge
Milky Way: Center of the galaxy, football shape, pop II stars, little gas and dust, supermassive black hole at the center
Galactic Disk
Milky Way: Flattened shape, spiral arms, both pop I & II stars, interstellar gas, dust, and pop I stars associated with spiral arms
Halo
Milky Way: Contains globular clusters, is spherical in shape, contains, pop II stars and very little interstellar gas and dust
Density Wave Theory
Milky Way: Says that the spiral structure is a wave that moves through the disk causing the stars and gas to clump up along the wave; the spiral arms are where the stars pile up as they orbit the center
Self-Propagating Star Formation
Milky Way: Uses the shock waves from supernova explosions to shape the spiral pattern; when a supernova shock wave reaches a gas cloud it compresses the cloud to stimulate the formation of stars
Pop I Stars
Milky Way: Disk component of the galaxy; ages 0-10 Billion; youngest are in spiral arms; orbits are orderly
Open Clusters
Young star clusters made of Pop I stars are called ______ loosely bound together
Pop II Stars
Milky Way: Spheroidal component (stellar halo & bulge); Old: ages 10-13 billon years; Masses are less than or equal to .8 solar masses; Randomly orbits
Globular Clusters
Old star clusters called ________ because they swarm around the center
Elliptical Galaxies
Galaxies: Smooth and Elliptical in appearance
Elliptical Galaxies
Galaxies: They have much more random star motion than orderly rotational motion
Elliptical Galaxies
Galaxies: They have no new star formation occurring now & no hot, bright, massive stars in them
Elliptical Galaxies
Galaxies: No spiral structure
Spiral Galaxies
Galaxies: Flattened disks with a spiral pattern in the disk
Spiral Galaxies
Galaxies: They have more orderly, rotational motion than random motion
Spiral Galaxies
Galaxies: They have some or a lot of gas and dust between the stars
Spiral Galaxies
Galaxies: Can have new star formation occurring in the disk, particularly in the spiral arms
Spiral Galaxies
Galaxies: They have spiral structure
Irregular Galaxies
Galaxies: No definite structure
Irregular Galaxies
Galaxies: Stars ar bunched up; patches randomly distributed throughout the galaxy
Irregular Galaxies
Galaxies: Some have a lot of dust and gas
Irregular Galaxies
Galaxies: small and faint
Rich Clusters
Clusters with hundreds to thousands of galaxies
Poor Clusters
Clusters with only a handful of galaxies
Local Group
Two large Spirals
230 Million
It takes __________ years for the Sun to go around the Milky Way once.
Virgo Cluster
The Closet Large Cluster to us is called the __________.