Astronomy Final Chapter 17

Our Sun is considered to be a ______.

low-mass star

Which of the following types of data provide evidence that helps us understand the life tracks of low-mass stars?

H-R diagrams of globular clusters

Why is a 1 solar-mass red giant more luminous than a 1 solar-mass main-sequence star?

Fusion reactions are producing energy at a greater rate in the red giant.

Which of the following describes a star with a hydrogen-burning shell and an inert helium core?

It is a subgiant that grows in luminosity until helium fusion begins in the central core.

Which is more common: a star blows up as a supernova, or a star forms a planetary nebula/white dwarf system?

Planetary nebula formation is more common.

This diagram represents the life track of a 1 solar-mass star from its pre-main-sequence stages to just before its final death. Refer to the life stages labeled with roman numerals.
During which stage is the star’s energy supplied by primarily by gravitational contraction?

ii Stage ii is the protostar stage during which energy comes from gravitational contraction.

This diagram represents the life track of a 1 solar-mass star from its pre-main-sequence stages to just before its final death. Refer to the life stages labeled with roman numerals.
During which stage does the star have an inert (nonburning) helium core?

iv Stage viii is a double shell-fusion red giant, which has an inert carbon core.

This diagram represents the life track of a 1 solar-mass star from its pre-main-sequence stages to just before its final death. Refer to the life stages labeled with roman numerals.

Which stage lasts the longest?

iii Stage iv is the subgiant stage, when the star has exhausted its core hydrogen and fuses hydrogen in a shell around the core. This stage is not its longest stage of life.

This diagram represents the life track of a 1 solar-mass star from its pre-main-sequence stages to just before its final death. Refer to the life stages labeled with roman numerals.

During which stage does the star have an inert (nonburning) carbon core surrounded by shells of helium and hydrogen burning?

viii Stage viii is when the star is expanding as a double-shell burning red giant, which means it has an inert carbon core surrounded by shells of helium fusion and hydrogen fusion.

This diagram represents the life track of a 1 solar-mass star from its pre-main-sequence stages to just before its final death. Refer to the life stages labeled with roman numerals.

What will happen to the star after stage viii?

Its outer layers will be ejected as a planetary nebula and its core will become a white dwarf.

Carbon fusion occurs in high-mass stars but not in low-mass stars because _________.

the cores of low-mass stars never get hot enough for carbon fusion

Which event marks the beginning of a supernova?

The sudden collapse of an iron core into a compact ball of neutrons.

Suppose that the star Betelgeuse (the upper left shoulder of Orion) were to supernova tomorrow (as seen here on Earth). What would it look like to the naked eye?

Betelgeuse would remain a dot of light but would suddenly become so bright that for a few weeks we’d be able to see this dot in the daytime.

Suppose that hydrogen, rather than iron, had the lowest mass per nuclear particle. Which of the following would be true?

Nuclear fusion could not power stars.

Observations show that elements with atomic mass numbers divisible by 4 (such as oxygen-16, neon-20, and magnesium-24) tend to be more abundant in the universe than elements with atomic mass numbers in between. Why do we think this is the case?

At the end of a high-mass star’s life, it produces new elements through a series of helium capture reactions.

A spinning neutron star has been observed at the center of a ______.

supernova remnant

You discover a binary star system in which one star is a 15 MSun main-sequence star and the other is a 10 MSun giant. How do we think that a star system such as this might have come to exist?

The giant must once have been the more massive star, but it is now less massive because it transferred some of its mass to its companion.

Tidal forces are important to the Algol system today but were not important when both stars were still on the main sequence. Why not?

Main-sequence stars in a system like the Algol system are small compared to their physical separation.