T2: Lec 9-11

Question 1

Why do stars twinkle?

Answer 1

The atmosphere refracts starlight in random directions through water particles in the air

Scintillation is the term for the refraction of light through the atmosphere.

Question 2

What is scintillation?

Answer 2

The refraction of light through the atmosphere

Scintillation causes stars to appear to twinkle.

Question 3

Why are telescopes placed on mountains or in space?

Answer 3

To reduce atmospheric refraction

Mountains have less atmosphere, and space has no atmosphere.

Question 4

What does ‘good seeing’ refer to?

Answer 4

Places without much light and very dry atmospheres

Question 5

Why do planets not twinkle like stars?

Answer 5

Planets emit light as a column instead of a thin line due to their proximity

Their light can become blurry but does not twinkle.

Question 6

Define a star.

Answer 6

A luminous ball of gas powered by nuclear fusion, studied through different wavelengths of light

Question 7

What are the main components of a star?

Answer 7

• Hydrogen
• Helium

Question 8

What factors affect the velocity of molecules in a gas?

Answer 8

Temperature of gas and pressure

Question 9

What holds gas together in a star?

Answer 9

Gravity due to mass pulled into a single point

Question 10

What is fusion in the context of stars?

Answer 10

The process of smashing two atoms together to create energy

Question 11

What is the outcome of hydrogen fusion in stars?

Answer 11

4 hydrogen protons turn into 1 helium atom and release excess energy

Question 12

What is the relationship between temperature and nuclear fusion?

Answer 12

Higher temperatures allow for nuclear fusion; lower temperatures prevent it due to mutual electrical repulsion

Question 13

What are the colors of stars from coolest to hottest?

Answer 13

• Red
• Orange
• Yellow
• White-Blue
• Blue

Question 14

What factors determine the brightness of stars?

Answer 14

• Distance
• Size
• Temperature

Question 15

How is luminosity related to temperature?

Answer 15

Luminosity is proportional to the fourth power of temperature

Question 16

What is the HR diagram?

Answer 16

A graph plotting stars’ luminosity against their temperature

Question 17

How can stellar mass be measured?

Answer 17

Using the orbit of binary stars and Kepler’s equation

Question 18

What is the solar mass of the sun?

Answer 18

1 solar mass

Question 19

What are sunspots?

Answer 19

Dark spots on the surface of stars caused by magnetic forces

Question 20

What is helioseismology?

Answer 20

The study of the sun’s interior using seismic waves

Question 21

What are solar flares?

Answer 21

Hot plasma full of energetic particles that fly off at high speed

Question 22

What defines a brown dwarf star?

Answer 22

A celestial body larger than gas giants but lacks the mass for nuclear fusion

Question 23

What is the ultimate fate of a white dwarf?

Answer 23

It cools down and fades away

Question 24

What happens during the stellar evolution of low-mass stars?

Answer 24

• Birth in nebular stellar nurseries
• Main sequence
• Helium core collapse
• Planetary nebula phase
• White dwarf phase

Question 25

What occurs during a supernova? How does it relate to rebound height?

Answer 25

A high-mass star collapses and releases energy in an explosion explained through Rebound height with the shockwave from core collapse transfering momentum and energy to layers of the star. This energy is transfered from layer to layer until the outer most layer of the star has extremely high velocity and his launched very far out into space. This high velocity and distance reached of the outermost particle in the supernova is explained through rebound height.

Question 26

What is a neutron star?

Answer 26

Very small and highly dense celestial object mainly made of packed neutrons thought to have been formed from the gravitational collpase of the remnant of a high mass massive star after a supernova explosions. (in the case the high mass star has insufficient mass to produce a black hole instead) A star formed when electrons and protons combine to create neutrons

Question 27

What is a black hole?

Answer 27

An object formed from the collapse of a massive star that absorbs light

Question 28

What are standard candles?

Answer 28

Intrinsic brightness of certain events used to measure astronomical distances

Question 29

How can HR diagrams help measure stellar age?

Answer 29

By observing colors and types of stars present in clusters

Question 30

What indicates an older star cluster on an HR diagram?

Answer 30

A higher number of red supergiants

Question 31

Fill in the blank: A brown dwarf is a '_______'.

Answer 31

Failed star

Question 32

There's two stars, one of which as a temperature 2x that of the other one. What is the difference in luminosity?

Answer 32

The luminosity of the hotter star is about 16x brighter than the cooler one.

Question 33

Explain rebound height

Answer 33

the height an object reaches after hitting a surface. a measure of elasticity and how "bouncy" an object is. If more than one object is stacked on another, the energy from the bottom most object to the top most object is continually transferred to the next layer up. This kinetic energy is compounded until the outermost object has extremely high amounts of transffered kinetic energy and is launched upwards.