Deck 12: Stellar Evolution

Question 1

As a star like the Sun exhausts hydrogen in its core, the outer layers of the star become hotter and more luminous.

Answer 1

False

Question 2

Observing star clusters will give astronomers needed data for stellar evolution because all the stars are the same age.

Answer 2

True

Question 3

Astronomers determine the internal structure of a star by using stellar models, since they cannot "see" into the interior of a star.

Answer 3

True

Question 4

All the elements heavier than helium on the periodic table, including the ones in your body, were created in the cores of massive stars.

Question 5

To determine the structure of the interior of a star, astronomers must balance density, luminosity, and ____.

A) mass
B) temperature
C) mass and temperature
D) mass and opacity
E) temperature and opacity

Question 6

Stellar models can easily be accomplished by using a simple hand calculator.

Question 7

Open clusters are older than globular clusters.

Question 8

Brown dwarfs are ____.

A) stars with a very thick dust sphere around them, so they appear "brown"
B) low mass M-type stars with hundreds of planets
C) an anomaly because they are extremely small but have relatively high temperature
D) protostars that could not ignite the fusion of hydrogen at their core
E) has a surface temperature of 2500 K by fusing hydrogen

Question 9

What is the upper limit of a brown dwarf's size?

A) no upper limit
B) 0.50 solar masses
C) 0.10 solar masses
D) 0.08 solar masses
E) less than 0.08 solar masses

Question 10

There is a mass-luminosity relationship because stars support their weight by generating energy, and more massive stars have more weight to support.

Question 11

The helium flash stage will always completely destroy a star and any planets nearby it

Question 12

Degenerate matter has two peculiar properties that can affect a star.  One is that the degenerate gas resists compression, and the other is that the degenerate gas ____.

A) is not density dependent
B) does depend on temperature
C) does not depend on temperature
D) is not pressure dependent.
E) does depend on the type of nuclei present

Question 13

Giant and supergiant stars are rare because they do not form as often as main-sequence stars.

Question 14

When the Sun moves off the main sequence, it will initially become a red supergiant.

Question 15

An average star spends about 90% of its life on the main sequence.

Question 16

The age of a star cluster can be approximated by finding its turnoff point in the distribution of data points that represent stars on the H-R diagram.

Question 17

Astronomers can determine the interiors of main-sequence stars by _____.

A) studying their atmospheres
B) creating stellar models
C) detailed observations of the Sun
D) using the Hertzsprung-Russell Stellar Model (HRSM)
E) satellite observations of the closest stars

Question 18

The energy emitted from the surface of a main-sequence star is less than the energy generated in the core.

Question 19

The fusion of helium into carbon will take a temperature of at least

A) 5 million degrees kelvin
B) 10 million degrees kelvin
C) 50 million degrees kelvin
D) 100 million degrees kelvin
E) 600 million degrees kelvin

Question 20

As a one-solar-mass star evolves off the main sequence, it will probably undergo a _____.

A) nova burnout
B) helium flash
C) hydrogen flash
D) helium bang
E) carbon flash

Question 22

Cepheid variable stars are classified as either ____.

A) Type A or Type B
B) Type I or Type II
C) Class A or Class B
D) Class I or Class II
E) Type C or Type R

Question 23

Observing star clusters will give astronomers needed data for stellar evolution because all the stars in the cluster have the same ____.

A) masses
B) temperatures
C) ages
D) luminosities
E) apparent magnitudes

Question 24

Which atom is the end result of the triple alpha process?

A) carbon
B) helium
C) hydrogen
D) iron
E) beryllium

Question 25

Why do Cepheids pulsate?

Question 26

Explain how the age of a star cluster provides evidence of stellar evolution.

Question 27

Why are massive stars more luminous than low-mass stars? That is, why is there a mass-luminosity relation?

Question 28

Why is the Cepheid's period related to their luminosity?

Question 29

Globular clusters have approximately how many stars?

A) 100,000 - 1,000,000
B) 10,000 - 90,000
C) 5,000 - 10,000
D) 1000 - 5000
E) less than 1000

Question 30

Why is there a lower end in the main sequence of the H-R diagram?

Question 31

Cepheid and RR Lyrae variable stars change their brightness by ____.

A) atmospheric explosions of hydrogen gas
B) internal changes in their fusion processes
C) a combination of atmospheric explosions and internal changes
D) a combination of atmospheric explosions and physically pulsating
E) changing its period between pulses

Question 32

Cepheid variables can be used to determine distances because their _____________ can be determined from their _____________.

Question 33

Because of the period-luminosity relation for Cepheids and RR Lyrae variable stars, astronomers are able to _____

A) determine the relationship between the period of pulses and luminosity
B) measure the mass of a star
C) calculate a star's diameter
D) determine the chemical composition of a Type I Cepheid
E) narrow their study to eclipsing binary stars only

Question 34

Figure 12-1: Main-Sequence Stars
What is the approximate age of the star cluster in the accompanying figure (Figure 12-1)?

A) 10 million years
B) 100 million years
C) 10 billion years
D) 100 billion years
E) Cannot be determine from the given data.

Question 35

Stars support their weight by generating ____.

A) magnetic fields throughout the star
B) magnetic fields throughout the star
C) energy in their centers
D) magnetic-plasmas at their core
E) energy-plasmas at their core

Question 36

Where are the Cepheid and RR Lyrae variable stars located on the H-R diagram?

A) just above and to the right of B type stars
B) just above and to the right of O type stars
C) in the variable strip
D) in the instability strip
E) outside the H-R diagram as missing items

Question 37

A zero-age main-sequence star burns ________ in its core through fusion reactions.

Question 38

As a main-sequence star evolves off the main sequence, the helium core is contracting while the outer envelope is _______________.

Question 39

If you observe a variable star with a period of 50 days as a yellow, supergiant star, then you most likely have seen a(n) ____.

A) degenerate star
B) RR Lyrae variable star
C) eclipsing binary star
D) Cepheid variable star
E) Type I pulsar

Question 40

When a gas is so dense that most of its electrons are not free to change their energies, it is called _______________.

Question 41

Define nuclear fusion.

Question 42

List the two basic types of intrinsic variable stars.

Question 43

A(n) _______________star is any star that changes its brightness significantly and repeatedly.

Question 44

Helium fusion is sometimes referred to as the _______________  because three helium nuclei are needed to make a carbon nucleus, and because the helium nucleus is called an alpha particle.

Question 45

A open star cluster will have a(n) _____________ turn-off point than an older star cluster.

Question 46

The instability strip on the H-R diagram is the location for what type of stars _______________.

Question 47

Briefly explain why there is a main sequence on the H-R Diagram.

Question 48

What is degenerate matter?

Question 49

Explain how one of the four laws of stellar structure works.

Question 50

List the four laws of stellar structure.

Question 51

Why is there an upper end in the main sequence of the H-R diagram?

Question 52

The two elements a one-solar-mass star uses over the course of its entire evolution are   _______________ and _____________.

Question 53

The lower limit for a main-sequence star is _______________ solar masses.

Question 54

The period-luminosity relation for Cepheid and RR Lyrae variable stars can be used for ______________.

Question 55

Variables of a certain type are called Cepheid variables because the first one discovered was in the _____________ Cepheus.