Hubble
Largest telescope
Used cepheid variable stars to
measure distance to nebula
Galaxies
Hubble discovered universe is
billions of galaxies
Cosmology – study of the universe, how it formed, how is today and how it will end. Spiral
Elliptical
Irregular & Dwarf
Active galaxies
quasars
Arched lanes of stars like the Milky Way
Spiral Arms – young, hot, blue stars, HII regions on going star formation
Central Bulges – Yellow/Red color, old stars, with low metal content. Little star formation.
Spiral
arm structure originating at end of a bar-shaped region in the center of the galaxy
No spiral
Round
arms
to Flat ellipse
Devoid of interstellar gas and dust
Old, red, stars with small amounts of
metals
Giant Ellipticals – rare
Dwarfs Ellipticals – very common
Don’t
fit into the other type
Rich in interstellar gas and dust
Have both old and young stars, but mainly younger stars
10% of known galaxies
Examples: Large and Small Magellanic
Clouds Southern Hemisphere
Which
galaxy type has the oldest stellar population?
A)
Spiral
B) Barred Spiral
C) Elliptical
D) Irregular
Which
galaxy type has the oldest stellar population?
A) Spiral
B) Barred Spiral
C) Elliptical
D) Irregular
Look
like stars but emit large amounts of energy as radio waves
Have a large redshift, therefore they are very far away!
Believed to originate from a Black Hole
Since they are so far away, it is essentially like looking back in time:
Quasars are the Oldest objects we have observed in the universe…they were formed when the universe was young!
Quasars emit in an large range: Radio to X-ray!
Extreme amounts of radiations
Extremely luminous
More than
“just starlight”
Do
galaxies exist independently or are they parts of groups of galaxies?
Yes – Galaxies are independent
No – Galaxies exist in groups
