Astro Test 2

Question 1

A high-luminosity star …

A: is always at a larger distance than a low-luminosity star
B: emits more light than a low-luminosity star
C: is always redder than a star with a lower luminosity
D: is at a lower temperature than a low-luminosity star
E: is always at a smaller distance than a low-luminosity star

Answer 1

B

Question 2

If a red giant appears the same brightness as a red main sequence star, which one is
farther away?

A: the red giant
B: we cannot tell
C: it depends on the phase of the Moon
D: the main sequence star
E: they are at the same distance

Answer 2

A

Question 3

The heaviest nuclei of all are formed …

A: during helium burning
B: as part of the p-p chain
C: during carbon burning
D: during a supernova explosion
E: during all stages of stellar evolution of massive stars

Answer 3

D

Question 4

Fill in the blank in the following chemical reaction that occurs in the Sun:
Hydrogen-2 + proton = _____ + energy:

A: Hydrogen-2
B: Hydrogen-1
C: Helium-3
D: Carbon-12
E: Helium-4

Answer 4

C

Question 5

5. Which of the following has the smallest radius?

A: type A main sequence star
B: main sequence star with surface temperature 8000 K
C: type K main sequence star
D: white dwarf
E: neutron star

Answer 5

E

Question 6

Why does the main sequence part of a star’s life end?

A: The Helium in the core is exhausted.
B: The gravitational force is no longer large enough to balance the pressure.
C: The Hydrogen in the core is exhausted.
D: The temperature drops so that nuclear reactions are no longer possible.
E: Much of the mass of the star has evaporated.

Answer 6

C

Question 7

Which of the following will have the shortest lifetime on the main sequence?

A: main sequence star with surface temperature 20000 K
B: main sequence star with surface temperature 3000 K
C: main sequence star with luminosity one tenth that of the Sun
D: the Sun
E: main sequence star with mass 2 times the Sun’s

Answer 7

A

Question 8

Many of the brightest 100 stars viewed from Earth are not on the main sequence
(even though most stars are) because …

A: only high mass stars formed near to us in the Galaxy.
B: the most luminous stars are giants and supergiants that have already
finished their main sequence lifetimes.
C: our region of the Galaxy is very young.
D: the main sequence is the shortest part of a star’s life so stars do not spend
much time there.
E: our region of the Galaxy is very old.

Answer 8

B

Question 9

A 2-solar-mass main sequence star is at the same distance as a 0.2-solar-mass main
sequence star. Which star appears brighter?

A: depends on the phase of the Moon
B: the 2 solar mass main sequence star appears brighter
C: the stars are approximately the same brightness
D: the 0.2 solar mass main sequence star appears brighter
E: we cannot tell with the information given

Answer 9

B

Question 10

The temperature of the photosphere of the Sun is closest to …

A: 10^7 Kelvin
B: 10^6 Kelvin
C: 100 Kelvin
D: 600,000 Kelvin
E: 6000 Kelvin

Answer 10

E

Question 11

An estimate of the number of communicating / technological civilizations that we
expect in our Galaxy would be a larger number if …

A: the average lifetime of a communicating civilization were smaller
B: the star formation rate in our Galaxy were smaller
C: the average number of planets that could support life for each star were larger
D: it were more difficult for life to develop intelligence, once life had formed
E: a smaller percentage of stars formed planets

Answer 11

C

Question 12

If the Sun had twice its mass, then which of these planets would be in its habitable
zone?

A: Mercury
B: Venus
C: Earth
D: Neptune
E: Jupiter

Answer 12

E

Question 13

What is the exoplanet’s orbital period, and the percent brightness drop in light, for
the case in the image above from the Kepler Exoplanet Transit Hunt activity?

A: 60 days and 0.15 %
B: 20 days and 0.15 %
C: 10 days and 0.15 %
D: 5 days and 0.30 %
E: 60 days and 0.30 %

Answer 13

D

Question 14

How do astronomers measure the temperature of stars?

A: The inverse square law is used.
B: Temperature is determined from the radius of the star that is measured by
radar.
C: By looking at which absorption lines are present in the star’s spectrum.
D: The rate of change of the color of the star is measured.
E: By comparing the luminosity and apparent brightnesses.

Answer 14

C

Question 15

In the inverse square law activity above, what would the wattage of the top
lightbulb need to be, such that it appeared as bright as the bottom lightbulb which
is a 25-Watt bulb?

A: 400 Watts
B: 100 Watts
C: 50 Watts
D: 25 Watts
E: 20 Watts

Answer 15

B

Question 16

The largest fraction of nearby stars (e.g., within 100 light years) are …

A: neutron stars
B: Sun-like stars
C: blue main sequence stars
D: red main sequence stars
E: blue supergiants

Answer 16

D

Question 17

Which of the stars, in the diagram above, is the hottest?

A: A
B: B
C: C
D: D
E: E

Answer 17

D

Question 18

If they were all formed at the same time, which of the stars in the diagram above
will live the longest?

A: A
B: B
C: C
D: D
E: E

Answer 18

B

Question 19

The parallax angle of a nearby star is measured to be 0.02 arcseconds. What is the
distance to the star?

A: 20 parsecs
B: 2 light years
C: 50 parsecs
D: 0.2 light years
E: 200 light years

Answer 19

C

Question 20

Which of the following is the sequence of events for a 40-solar mass star
(one of the most-massive stars)?

A: planetary nebula, protostar, Sun-like star on main sequence, blue giant,
red giant
B: stellar nursery, protostar, Sun-like star on main sequence, red giant,
planetary nebula, white dwarf
C: stellar nursery, blue giant, Sun-like star on main sequence, red giant,
Type II supernova, neutron star
D: stellar nursery, protostar, blue star on main sequence, Type II supernova,
black hole
E: black hole, neutron star, white dwarf, Sun-like star on main sequence,
red giant, Type II supernova

Answer 20

D

Question 21

Star A is 9 times as luminous as Star B. The two stars appear the same brightness.
What is true about their distances?

A: Star A is 9 times farther away than Star B.
B: Star B is 9 times farther away than Star A.
C: Star A is 3 times farther away than Star B.
D: Star B is 3 times farther away than Star A.
E: Stars A and B are at the same distance.

Answer 21

C

Question 22

In the p-p chain, shown in the above diagram, what particles must be input in order
to produce one 4He nucleus?

A: 8 protons, but 2 of them are returned when the 4He is produced
B: 6 protons, but 2 of them are returned when the 4He is produced
C: 2 photons and 2 positrons
D: 2 protons and 4 neutrons
E: 4 neutrons

Answer 22

B

Question 23

What is the name of the slightly cooler layer of the Sun just outside the
photosphere?

A: core
B: corona
C: convective zone
D: chromosphere
E: radiative zone

Answer 23

D

Question 24

How does a star move on the H-R diagram during the period of time it is converting
hydrogen to helium in its core?

A: It moves from the far lower right corner of the diagram to the far upper left
corner of the diagram, along the main sequence.
B: It moves from the upper left of the diagram to the lower right of the diagram,
along the main sequence.
C: It remains nearly fixed at a certain point on the main sequence and does
not move on the H-R diagram.
D: It moves from the upper right of the diagram to the lower left of the diagram.
E: It moves from the lower left of the diagram to the upper right of the diagram

Answer 24

C

Question 25

If the entire mass of Earth were concentrated in a region the size of a marble, the resulting object would be ... ## Footnote A: a Sun-like star B: a white dwarf C: a neutron star D: a black hole E: a planetary nebula

Answer 25

D

Question 26

Which is the smallest object? ## Footnote A: a neutron star B: the Solar System C: the Sun D: a dwarf galaxy E: the Eagle nebula

Answer 26

A

Question 27

A galaxy has an H-alpha emission line observed at a wavelength 10 percent larger than the rest wavelength of H-alpha. What is the redshift of the galaxy? ## Footnote A: 10 B: 0.001 C: 0.1 D: 1 E: -0.001

Answer 27

C

Question 28

What is in this image? (right) ## Footnote A: supernova remnant B: irregular galaxy C: planetary nebula D: globular star cluster E: star forming region

Answer 28

A

Question 29

Which is the most luminous? ## Footnote A: nova B: supernova C: quasar D: the Sun E: white dwarf

Answer 29

C

Question 30

Which contains the most stars? ## Footnote A: an open star cluster B: a globular star cluster C: a spiral galaxy D: the Solar System E: the alpha Centauri star system

Answer 30

C

Question 31

Galaxy A appears twice the angular size of Galaxy B. Assuming the two galaxies have the same physical size in kiloparsecs, which of the following is true? ## Footnote A: Galaxy A is 2 times farther away than Galaxy B. B: Galaxy B is 2 times farther away than Galaxy A. C: Galaxy A and B are at the same distance. D: Galaxy A is 4 times farther away than Galaxy B. E: Galaxy B is 4 times farther away than Galaxy A.

Answer 31

B

Question 32

What fundamental particles make up a Helium-3 atom? ## Footnote A: 2 up quarks, 1 down quark, 1 electron B: 6 up quarks, 6 down quarks, 2 electrons C: 3 up quarks, 3 down quarks, 3 electrons D: 1 proton, 2 neutrons, 1 electron E: 5 up quarks, 4 down quarks, 2 electrons

Answer 32

E

Question 33

In what box does the galaxy in the bottom center belong in this Hubble tuning fork diagram? ## Footnote A: E1 B: Irr C: Sc D: SBb E: SBc

Answer 33

D

Question 34

Which statement is FALSE? ## Footnote A: planetary nebulae can have layers because of pulsating stars B: planetary nebulae usually last tens of thousands of years C: a planetary nebula will be part of the end state of the Sun D: planetary nebulae usually have black holes at their centers E: planetary nebulae are a few light years in size

Answer 34

D

Question 35

Which statement is TRUE? ## Footnote A: Stars form in molecular clouds, where temperatures are about 10 Kelvin. B: A cloud will collapse and form stars if its mass is a lot less than its Jeans mass. C: A nova outburst typically only happens once in a star’s life. D: Stars usually form in isolation, far away from other stars E: The Crab supernova, in our galaxy, went off about 8 years ago.

Answer 35

A

Question 36

How tiny a spot is the Hubble Deep Field? ## Footnote A: About 1/2 of the entire sky. B: About 1/5 of the entire sky. C: About 1/10 of the entire sky. D: About 1/50 of the entire sky. E: The size of President Roosevelt’s eye on a dime held at arm’s length.

Answer 36

E

Question 37

Among these choices, what is the last thing that happens in the history of the Universe? ## Footnote A: electrons join with nuclei to make atoms B: quarks join together to make protons and neutrons C: nucleosynthesis D: the Planck epoch E: the Big Bang expansion begins

Answer 37

A

Question 38

If a galaxy had no dark matter, we would observe ... ## Footnote A: the entire galaxy would approach us at a faster velocity, and we would observe a redshift B: the entire galaxy would recede from us at a faster velocity, and we would observe a redshift C: the rotation velocity would remain constant with increasing distance D: the rotation velocity would decrease with increasing distance like the Keplerian curve in our Solar System E: the rotation velocity would increase with increasing distance like the Keplerian curve in our Solar System

Answer 38

D

Question 39

How many times bigger is the Local Group of galaxies in which the Milky Way resides than the Milky Way itself? ## Footnote A: it is not bigger than the Milky Way B: about 100 times bigger C: about 1040 times bigger D: about 1010 times bigger E: about 1 million times bigger

Answer 39

B

Question 40

Which one of the following is FALSE? ## Footnote A: Irregular galaxies, although small, often have a lot of star formation taking place in them. B: Barred spiral galaxies have similar properties to normal spirals, except for the “bar” feature. C: Galaxy collisions destroy most of the stars in the galaxies involved. D: Most galaxies appear to be receding from the Milky Way Galaxy. E: Most elliptical galaxies contain only old stars.

Answer 40

C

Question 41

If a galaxy is moving away from us the wavelength of the light it emits will be ... ## Footnote A: unaffected. B: blueshifted. C: increased. D: decreased. E: distorted.

Answer 41

C

Question 42

The stars in the halo of our Milky Way Galaxy are ... ## Footnote A: in a very flat distribution. B: very close together compared to stars in the disk. C: older and bluer than those in the disk. D: never in globular clusters. E: older and redder than those in the disk.

Answer 42

E

Question 43

The supermassive black hole in the center of the Milky Way has a mass of ... ## Footnote A: 10 solar masses B: 1,000 solar masses C: 4 million solar masses D: 100 billion solar masses E: 100 solar masses

Answer 43

C

Question 44

In the figure above, how would you calculate the fraction of the mass of the gas in the universe that is in the form of Helium? ## Footnote A: take 4×4 for the mass of Helium, and divide by 4×4 + 48×1 for the total mass B: take 4×1 for the mass of Helium, and divide by 48×1 for mass of Hydrogen C: take 4 for the mass of Helium, and divide by 48 for the mass of Hydrogen D: take 48×1 for the mass of Hydrogen, and divide by 4×4 + 48×1 for total mass E: take 48×4 for the mass of Hydrogen, and divide by 4×1 + 48×4 for total mass

Answer 44

A

Question 45

Which force has the photon as its boson? ## Footnote A: strong B: weak C: electromagnetic D: gravity E: none of the forces do

Answer 45

C

Question 46

Which mysterious phenomena do scientists attribute to dark energy? ## Footnote A: The increasing rate of expansion of the Universe. B: Mysterious bonding that holds atoms together. C: The creation of the cosmic microwave background. D: The formation of Helium through nucleosynthesis. E: Dark energy causes all of the above.

Answer 46

A

Question 47

Why can we NOT see back the whole way to the time Big Bang expansion began? ## Footnote A: Not enough photons were produced. B: Radiation is blueshifted out of the visible range. C: Our telescopes could never be powerful enough. D: The radiation scatters off matter frequently so the Universe is opaque. E: It would take too long for light to travel that far.

Answer 47

D

Question 48

What are the "standard candles" that were used to determine the Universe is accelerating? ## Footnote A: spiral galaxies B: elliptical galaxies C: Type Ia supernovae D: light bulbs E: Type II supernovae

Answer 48

C

Question 49

An older star cluster ... ## Footnote A: contains hotter stars than a younger star cluster. B: has a main sequence turnoff farther to the left on the H-R diagram. C: has a main sequence turnoff farther to the right on the H-R diagram. D: would never be located in the halo of a galaxy. E: has a bluer color than a younger star cluster.

Answer 49

C

Question 50

Which of the following statements is TRUE? ## Footnote A: One or two supernova are observed to go off in the Milky Way galaxy each year. B: Type II supernovae are produced by the death of a massive star. C: Type Ia supernovae show a lot of strong hydrogen lines in their spectra. D: Type Ia supernovae are produced when a neutron star collapses to become a black hole. E: When a planetary nebula is produced it can outshine an entire galaxy.

Answer 50

B

Question 51

What is the proton-proton chain

Answer 51

a long-lasting source of energy in stars: 4 protons combine to make helium-4 (2 protons and 2 neutrons) and release energy in gamma rays

Question 52

Step 1 on p-p chain

Answer 52

two protons collide at very high speed, and stick together; one of them changes into a neutron; ends with a Deuterium nucleus ( 2H : 1 proton and 1 neutron, bound together), plus released energy

Question 53

Step 2 of p-p chain

Answer 53

euterium nucleus from Step 1 collides with another proton, and makes a Helium-3 nucleus ( 3He : 2 protons and 1 neutron, bound together), plus some more excess energy released

Question 54

Step 3 of p-p chain

Answer 54

wo Helium-3 nuclei combine to make a Helium-4 nucleus ( 4He : 2 protons and 2 neutrons, bound together), releasing back 2 protons in the process and some more extra energy

Question 55

Layer of sun: at the center; high density and temperature; where nuclear reactions occur and gamma rays are produced

Answer 55

core

Question 56

Layer of sun: hotons are repeatedly re-absorbed and re-emitted; the energy of an individual photon can take on average 170,000 years to pass through

Answer 56

radiative zone

Question 57

Layers of sun: hot gas rises and cold gas sinks; light traverses in about 1 week

Answer 57

convective zone

Question 58

Layers of sun: mperature 5,780 K; this is the "surface" of the Sun that we see; photons have been converted to visible wavelengths; can see "granules" due to convection bringing material up and down in cells

Answer 58

photosphere

Question 59

Layers of sun: red or orange color; temperature about 4,500 K; we see through this, down to the photosphere

Answer 59

chromosphere

Question 60

Layers of sun: an eruption coming out of Sun due to magnetic activity

Answer 60

flare

Question 61

Layers of sun: hoop-shaped eruption out of Sun due to magnetic activity

Answer 61

prominence

Question 62

Layers of sun: ow density; temperature about 1 million K; visible during solar eclipses

Answer 62

corona

Question 63

Layers of sun: charged particles coming from Sun’s surface, escaping to deep space; permeates the whole Solar System 3

Answer 63

solar wind

Question 64

Inverse square law

Answer 64

B = L/4𝝅d^2 or B=L / d^2