Stars

Question 1

Facts about

Main sequence stars (3)

Answer 1

• Fuse Hydrogen in core
• Majority of a star’s lifetime is here
• 0.1 - 10 R⊙

Question 2

Facts about

Red Giants (5)

Answer 2

• Hydrogen depleted, Helium fusion stars
• Star expands
• Outer layers cool
• Not much time spent in this stage
• 10 -> 1000R⊙

Question 3

Facts about

White Dwarfs (3)

Answer 3

• End state of most stars
• 0.01R_earth
• 25000K -> 3000K

Question 4

What are the types of

Star Clusters

Answer 4

• Open Clusters
• Globular Clusters

Question 5

Open Clusters (3)

Answer 5

• 100-1000 stars
• Found in disk of our galaxy
• Young stars (1Myr -> 1Gyr)

Question 6

Globular Clusters (4)

Answer 6

• 100,000 -> 1,000,000 stars
• Distributed all over the galaxy
• Old stars (12Gyr)
• Dense (100->1000 per cubic parsec)

Question 7

What is the equation for the

Central Pressure of Stars

Answer 7

P = (3GM^2)/(4πR^4)

P = Pressure, M = Mass of star, R = Radius of Star

Question 8

What is the equation for the

Ideal Gas Pressure Equation of a Star

Answer 8

P =(ρkBT)/µ

ρ = density, kB = boltzmann const, T = Temp, µ = mean mass per particle

Question 9

What is the equation for

Core Temperature of a Star

Answer 9

kBT = GMµ/R

kB = boltzmann constant, T = Temp, µ = mean mass per particle, M = mass

Thermal Energy = Gravitational Potential Energy

Question 10

What is the equation for

Lifetime of a star

Answer 10

t = E/L

t = liftetime, E = Total Energy supply, L = Luminosity

Question 11

What is the relationship of

Star Lifetime and Star mass

Answer 11

t ∝ M^-3

t = lifetime, M = mass

Inverse Relationship