Deck 18: The Formation of Stars and Planets

Question 1

Which of the following is an example of a newborn star?

A)An asymptotic giant branch star
B)A reflection nebula
C)A T Tauri star
D)A pulsar

Answer 1

A T Tauri star

Question 2

As a molecular cloud core collapses,what can we expect to occur?

A)The rotation rate increases,which inhibits the formation of a disk.
B)The rotation rate decreases,which inhibits the formation of a disk.
C)The rotation rate increases,which enhances the formation of a disk.
D)The rotation rate decreases,which enhances the formation of a disk.

Answer 2

The rotation rate increases,which inhibits the formation of a disk.

Question 3

Where are very young stars located in an H-R diagram?

A)Above and to the right of the main sequence
B)Lower left
C)Below the main sequence
D)In the upper left

Answer 3

Above and to the right of the main sequence

Question 4

Which of the following is a serious objection to catastrophic theories of the origin of the solar system?

A)Collisions between stars are rare events
B)The planets are much younger than the Sun
C)Material pulled from the Sun would have been too hot to form planets
D)A separate collision would have been needed to form each planet

Question 5

What happened to the gas that was left over in the solar nebula after the planets formed?

A)It was blown away by a strong wind
B)It fell back into the Sun
C)It was swept away by a passing star
D)It condensed to form the zodiacal light

Question 6

As an interstellar cloud collapses to become a star,its central parts at first heat up very slowly.Why?

A)Infrared radiation can escape and cool the cloud
B)The collapse is too slow to generate much energy
C)Any heated atoms escape from the collapsing cloud
D)The core of the cloud is degenerate

Question 7

The core of a proto-star remains relatively cool until which of the following happens?

A)The star becomes opaque
B)Nuclear reactions begin
C)The chemical composition of the star changes
D)Its spin slows significantly

Question 8

According to nebular theories,the planets formed from material that was

A)Pulled from the Sun during a collision with another star
B)Ejected from the Sun by an explosion
C)Captured by the Sun from interstellar space
D)Part of the collapsing cloud that formed the Sun

Question 9

The contraction of a gaseous cloud out of which a star and a planetary system form is caused by what kind of force?

A)Electric
B)Nuclear
C)Magnetic
D)Gravitational

Question 10

The H-R diagram of a cluster shows that the least massive stars lie above the main sequence (that is they are more luminous than main sequence stars).What can we conclude about the cluster?

A)It has an unusual chemical composition
B)Its least massive stars are more massive than the stars near the Sun
C)It is quite young
D)Its stars have large magnetic fields

Question 11

Which of the following clusters is the youngest?

A)Its least massive stars are just arriving on the main sequence
B)Its most massive stars are just arriving on the main sequence
C)Its least massive stars are just leaving the main sequence
D)Its most massive stars are just leaving the main sequence

Question 12

If nebular theories of the origin of the solar system are correct,then which of the following is a likely consequence?

A)There are many planetary systems in the galaxy
B)The Sun is much older than the planets
C)Fusion is not occurring in the Sun
D)The Sun once had a binary companion

Question 13

What process is responsible for the formation of a new star?

A)The collision of one or more stars
B)The collapse of part of a cloud of interstellar material
C)The gathering of material around a black hole
D)The collision of massive planets in interstellar space

Question 14

As an interstellar cloud collapses to become a star,its central region eventually becomes opaque.Why is this a significant development in the formation of the star?

A)Temperature can now begin to rise
B)The star now begins to rotate
C)The star now begins to radiate infrared radiation
D)Magnetic pressure now prevents further collapse

Question 15

What is the evolutionary status of a T Tauri star?

A)Main sequence star
B)Newborn star
C)Red giant
D)Old pulsar

Question 16

What were planetesimals?

A)Interplanetary grains
B)Bodies,as massive as the Earth,that formed the cores of the giant planets
C)Intermediate-size bodies that combined with others to form planets
D)Interstellar bodies captured by the Sun soon after it formed

Question 17

The solar system

A)Took several billion years to form
B)Underwent several intervals of planet formation separated by billions of years
C)Formed about 5 million years ago
D)Reached more or less its present form in less than a billion years

Question 18

Which of the following is not easily accounted for in current versions of the nebular theory of the origin of the solar system?

A)The Sun's equator lies nearly in the ecliptic
B)Planet-satellite systems resemble the solar system
C)The rotation of Venus
D)The planets orbit the Sun in the same direction

Question 19

Why do the H-R diagrams of young clusters show the least massive stars located above the zero-age main sequence?

A)They are always the first stars to form in a cluster
B)They take longer to reach the main sequence
C)They evolve away from the main sequence before more massive stars do
D)They are actually binaries,and thus seem overluminous

Question 20

An HR diagram is a plot of:

A)amplitude verses pressure.
B)luminosity verses surface temperature.
C)mass verses brightness.
D)pressure verses surface temperature.