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Astronomy Final ch. 15 - The Milky Way
Terms in this set (30)
3 major names associated with the history of the Milky Way Discovery
Immanuel Kant, William Parsons, Lord Rosse
Discovered a collection of stars "island universes" found far beyond the Milky Way
Built a large telescope that greatly improved resolution
found "glowing clouds" discovered earlier by Herschel; spiral nebulae
located in the M51 Whirlpool Galaxy, in constellation Canes Venatici; about 20M light years, has companion galaxy
Cepheid variable stars
pulsating stars that vary in brightness periodically
Types of Cepheid variable stars
metal rich type I, Metal-poor type II
Why did remote star clusters appear dimmer than expected?
Great clouds of dust in interstellar space block starlight
who discovered properties of Cepheid variable stars?
What did Harlow Shapley focus on? (in the discovery of interstellar matter)
RR Lyrae pulsating stars
What are RR Lyrae Variable Stars?
commonly found in globular clusters, similar to Cepheid variable stars in that distinctive period-luminosity relationships are used to determine stellar distances
What did Shapley discover?
globular clusters form a spherical distribution NOT centered on Earth
hydrogen atoms in the interstellar medium emit electromagnetic radiation in the _____ range
What is the primary means of mapping the galaxy
the emission of electromagnetic radiation in the radio range from hydrogen atoms
Why do protons and electrons act like tiny magnets?
intrinsic angular momentum b/c of spin
Protons and electrons within Hydrogen atoms can only spin in either parallel or opposite directions
What happens when electro spin flips?
hydrogen atoms gain or lose tiny amounts of energy
_____ at different locations along our line of sight move around the center of the galaxy at different speeds
Radio waves from different orbiting gas clouds exhibit slightly different _________
Measurements of differing _________ permit astronomers to map the galaxy
Our galaxy has ____ major spiral arms and shorter segments
Where is the Sun located?
near the short Orion spiral arm, between the larger Sagittarius arm and the Perseus arm
List the arms
orion, sagittarius, perseus, centaurus, cygnus
What do recent observations indicate about the Milky Way?
it possesses a bar of stars across its nuclear bulge
What are the 3 major components of our Galaxy?
disk, nuclear bulge, and halo
population 1 stars (young and metal rich, plus gas & dust)
old and metal poor stars
how far from the center of the Galaxy is the Sun?
What is the nearest known galaxy?
Sagittarius Dwarf Galaxy
What do the measurement of Doppler Shifts of the sagittarius Dwarf Galaxy reveal?
stars closer to the center orbit at greater speeds, stars further out move more slowly, the galaxy exhibits differential rotation
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