What are the three major types of galaxies?
Disk component are stars of all ages many glass clouds.
-Spheroid component bulge and halo old stars few gas clouds.
-Barred spiral galaxy has a band of stars across the bulge.
-Lenticular galaxy has a disk like spiral galaxy but much less dusty gas intermediate between spiral and elliptical.
-Elliptical all spheriodal component virtually no disk component.
-Irregular neither spiral nor elliptical. Blue white color indicates ongoing star formation.
How are galaxies grouped together?
Spiral galaxies are often found in group galaxies.
-Elliptical galaxies are Much more common in huge clusters of galaxies.
How do we measure the distances to galaxies?
Step one is to determine size of solar system using radar.
-Step two is to determines distance of star out to a few hundred light years using parallax.
-Step three is apparent brightness of stars cluster's main sequence tells us its distance.
-Step five apparent brightness of a white dwarf supernova tells us the distance to its galaxy
What is Hubble's law?
Distance of the farthest galaxies are measured from red shifts.
How do distance measurements tell us the age of the universe?
Hubble’s constant tells us the age if the universe
How do we observe the life histories of galaxies?
Deep in observation show us distant galaxies.
How did galaxies form?
-Matter originally file all of the space almost uniformly.
-Gravity of denser region pulled in surrounding matter.
-Denser regions contracted forming progoalatic clouds.
-H and He gases in these clouds formed first.
-Supernova explosions from the first stars kept Much of the gas from forming stars.
-Left over gas settles.
How do galaxies differ?
-The intensity of supernova explosions in starburst galaxies can drive galactic winds.
What are quasars?
Quasars powerfully radiate energy over a very wide range of wavelength indicating that They contain matter with a wide range of temperature.-Radio galaxies contain active nuclei shooting out vast jets of plasma which edit radio waves coming from electrons moving at near light speed.
-Lobes of radio galaxies can extend .
What is the power source for quasars and other active galactic nuclei?
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