The Great Debate 2 Flashcards
what is the name of the nebulae with distinct spiral pattern that Lord Rosse found?
island universes
who was the Great Debate b/w?
curtis and Shapley
what was the Great Debate about?
the nature of the spiral nebulae….were they similar to nebulae in MWG or were they distant island universes
- size of MWG
- nature of the spiral nebulae
how can we prove that the spiral nebulae are distant island universes? What do we need to measure?
determine distance to these spiral nebulae
who resolved the controversy of the Great Debate and how?
Edwin Hubble by discovering cepheid variable stars in the Great Spiral Nebula in Andromeda
Hubble measured the period of cepheid var stars in order to find what?
luminosity
Hubble combined the calculated luminosity of cepheid var stars with what in order to get the distance to the Great Spiral Nebula stars?
he combined luminosity w/ brightness
what drives astronomical discoveries today?
technology
what are the two major types of galaxies?
spiral and elliptical
what are the components of a spiral galaxy?
disk, spheroid component
what does the spheroid component of a spiral galaxy contain
mostly old stars, little gas and dust
what does the disk component of a spiral galaxy contain?
contains younger stars, gas and dust
hot gas regions are a sign of what process in the spiral arms?
new star formation
what are the components of elliptical galaxies
composed only of a spheroidal component
what do elliptical galaxies contain?
mostly old stars, almost no gas and dust. no new star formation
what is an irregular galaxy?
galaxies that aren’t spiral or elliptical
properties of irregular galaxies
contain stars gas and dust (much like spiral)
what are properties of poor clusters?
- few cluster members
- irregular shape
what are poor clusters dominated by?
spiral galaxies and dwarf irregular and dwarf elliptical galaxies
what are properties of rich clusters?
contain hundreds to thousands of galaxies
-spherical distribution
what are rich clusters dominated by?
dominated by elliptical and S0 galaxies
what is the Local Group?
a poor cluster containing our MWG and 2 other large spiral galaxies
what are superclusters?
clusters of galaxies that are also clustered
