Chapter 13

Question 1

What is the fundamental method of measuring the distance of nearby stars

Answer 1

Triangulation

Question 2

How do we find the distance using triangulation

Answer 2

We use parallax. We see the location of a star in January for example and then it’s location in July and draw a triangle using earth and that star

Question 3

What is the nearest star to the sun

Answer 3

The Proxima Centauri which is a member of a 3 star system called alpha centauri

Question 4

What is luminosity

Answer 4

It is the absolute brightness of a star, and the measure of the total amount of energy radiated by a star each second

Question 5

What is apparent brightness

Answer 5

It is how bright the star appears to be from earth, this depends on its luminosity and the distance of the star

Question 6

What does a high magnitude mean in luminosity of a star

Answer 6

It means the star is dim, the higher the magnitude the dimmer it is and the lower the magnitude the brighter it is

Question 7

What is absolute magnitude used for

Answer 7

Measuring a stars luminosity. It is the apparent magnitude the same star would have at 10 parsecs distance

Question 8

What does a stars color mean

Answer 8

How hot it is, reds are relatively cool while blue ones are hotter

Question 9

How do we measure their heat

Answer 9

Since they are black bodies, we only need to make observations of two wavelengths coming from them to determine their heat

Question 10

What is a stars spectrum

Answer 10

It is how the energy it emits at each wavelength is shown. It can show a stars composition, temperature, luminosity, velocity, and rotation speed

Question 11

How are star temperatures categorized

Answer 11

By letters going from highest to lowest; O B A F G K M, each type has 10 subdivisions from 0-9 the lower the number the hotter the star

Question 12

Who demonstrated the physical connection between temperature and absorption lines

Answer 12

Cecelia Payne

Question 13

How do we measure a stars motion

Answer 13

From the Doppler shift of its spectral lines

Question 14

What does Steven Boltzmann’s law state

Answer 14

The hotter the star the greater it’s luminosity

Question 15

How do stars differ in radius (dwarf stars, giant stars, supergiant stars)

Answer 15

Dwarf stars: equal to or less than the sun
Giant stars: between 10 and 100 times the sun
Supergiant stars: more than 100 times the sun

Question 16

What is the hertzsprung-Russell diagram

Answer 16

It plots stellar luminosity against surface temperature

Question 17

What is the dark curve called on the plot

Answer 17

It is called the main sequence

Question 18

Where do 90% of stars lie

Answer 18

In the main sequence

Question 19

What are the three classifications of stars in the HR diagram

Answer 19

Main sequence, giants, white dwarfs

Question 20

How do astronomers measure distances in the universe

Answer 20

They use the method of standard candles also called the spectroscopic parallax

Question 21

What are binary stars

Answer 21

They are two stars that revolve around each other as a result of their mutual gravitational attraction

Question 22

How do we detect if a star is a binary pair

Answer 22

Many stars are, we can detect it by visual binaries, Doppler shift, or eclipsing binaries

Question 23

What does mass determine on the HR plot

Answer 23

Where it lies on the main sequence.

Question 24

Can the masses of stars in the binary sequence be measured

Answer 24

Yes