Milky Way Galaxy: Structure, History, and Dark Matter

What are the Large and Small Magellanic Clouds?

The Large Magellanic Cloud (LMC) is the upper galaxy, and the Small Magellanic Cloud (SMC) is the lower galaxy.

What are the two types of spiral galaxies?

Unbarred and Barred Spiral Galaxies.

Which galaxy is an example of an unbarred spiral galaxy?

M74.

Which galaxy is an example of a strongly barred spiral galaxy?

NGC 1365.

What significant contributions did William & Caroline Herschel make?

They discovered Uranus, constructed large telescopes, measured the Sun's position in the Galaxy, and conducted brightness comparisons among stars.

What methodology did Herschel use to study the Milky Way?

He conducted observations from over 600 locations and counted every star, estimating distances by assuming uniform intrinsic luminosity.

What was Harlow Shapley's contribution to our understanding of the Milky Way?

He utilized Cepheid variable stars to gauge distances to globular clusters and estimated the Milky Way's size to be approximately 300,000 light years.

What did Herber Curtis argue about Andromeda?

He argued that Andromeda is a separate galaxy based on observing more novae in Andromeda compared to the Milky Way.

What was the outcome of the Great Debate regarding the size of the Milky Way?

Shapley estimated the Milky Way at 300,000 light years, Curtis at 30,000 light years, but the actual size was established as 105,700 light years.

What did Edwin Hubble discover about Andromeda in 1929?

He established that Andromeda is an independent galaxy, with a distance exceeding 900,000 light years.

What is the Orion Spur?

The Orion Spur is the arm of the Milky Way where our solar system is situated.

What are the major components of the Milky Way?

The Bulge, Disc, and Stellar Halo.

What is the galactic halo?

A sparse region surrounding the galaxy that houses globular clusters.

What is the significance of dark matter in the Milky Way?

Dark matter envelops the Milky Way, containing significant unidentified mass beyond typical visible matter.

What are the two theories on the formation of the Milky Way?

Monolithic Collapse and Multiple Merger.

What characterizes Pop I stars?

Younger, bluer stars found in the galactic disk with ongoing star formation.

What characterizes Pop II stars?

Older, redder stars located in the halo, devoid of gas and dust.

How does the Milky Way interact with dwarf galaxies?

It interacts gravitationally, forming stellar streams, such as with the Sagittarius Dwarf Galaxy.

What is predicted about the Milky Way's future interaction with the Andromeda Galaxy?

The Milky Way is on a collision course with the Andromeda Galaxy, set to merge in the future.