Milky Way Galaxy

Question 1

What is the length of the Milky Way Galaxy?

Answer 1

100,000 ly across

Question 2

How tall is the galaxy?

Answer 2

1000 ly

Question 3

What are the primary features of the galaxy?

Answer 3

disk, bulge, halo, globular clusters

Question 4

How do we see the galaxy?

Answer 4

Edge-on. If we could see from above, we would be able to see the spiral arms.

Question 5

How do stars orbit in the galaxy?

Answer 5

Stars in the disk all orbit in the same direction
with a little up-and-down. Orbits of stars in the
bulge and halo have random orientations

Question 6

What is the mass of the galaxy within Sun’s orbit?

Answer 6

1.0 x 10^11 MSun

Question 7

What is the orbital velocity law?

Answer 7

The orbital speed (v) and radius (r) of an object on
a circular orbit around the galaxy tells us the mass
(Mr) within that orbit. Mr = r * v^2 / G

Question 8

What is the star-gas-star cycle?

Answer 8

Recycles gas from old stars into new star systems.

Question 9

What is L2 and what distance is it at?

Answer 9

Is it the distance where the force of gravity is acting on the satellite and the Earth is equal to the force acting from the Sun and the satellite. It is 1% the distance of AU or 1.5 million kilometers. It allows for a stable orbit and will be dragged along orbit of Earth.

Question 10

What is the end fate of the galaxy?

Answer 10

All white dwarfs, eventually becoming brown dwarfs

Question 11

What is the metallicity of halo stars?

Answer 11

Less. This is because they are only old stars - population 2 stars. Halo stars formed first.

Question 12

What is the metallicity of disk stars?

Answer 12

2%, Population I stars include the sun and tend to be luminous, hot and young, concentrated in the disks of spiral galaxies. They are particularly found in the spiral arms. With the model of heavy element formation in supernovae, this suggests that the gas from which they formed had been seeded with the heavy elements formed from previous giant stars. About 2% of the total belong to Population I.

Question 13

What is the mass of the galactic centre?

Answer 13

4 Million MSuns

Question 14

What is dark energy?

Answer 14

Anti-gravity. 70% of universe.

Question 15

What is the fountain effect?

Answer 15

Multiple supernovae create huge hot

bubbles that can blow out of disk. Gas clouds cooling in the halo can rain back down on disk

Question 16

Where do stars tend to form in our galaxy?

Answer 16

Ionization nebulae
are found around
short-lived high-mass
stars, signifying active
star formation. In the disk.