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Suppose a particular star has a core that is undergoing several stages of fusion simultaneously, as shown in this diagram. Based on your understanding of stellar lives, the mass of this star is probably:

about 10 (or more) solar masses

Suppose a particular star has a core that is undergoing several stages of fusion simultaneously, as shown in this diagram. Which of the following statements about this star is most likely to be true?

The star will explode as a supernova within a few days.

The arrow in the photo on the left shows the star that we see as a supernova in the photo on the right. What can we conclude about this star?

It was a high-mass star with at least 8 times the mass of the Sun.

Suppose you had looked with your naked eye at the supernova on the night it was photographed in the "after" photo. Assuming that it was bright enough to see (it was), what would it have looked like to your naked eye?

Like a single star in the night sky.

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.

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.

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

During which stage is the star's energy supplied by primarily by gravitational contraction?


During which stage does the star have an inert (non-burning) helium core?


Which stage lasts the longest?


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


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.

We do not know for certain whether the general trends we observe in stellar birth masses also apply to brown dwarfs. But if they do, then which of the following would be true?

Brown dwarfs would outnumber all ordinary stars.

Consider a large molecular cloud that will give birth to a cluster of stars. Which of the following would you expect to be true?

A few massive stars will form, live, and die before the majority of the star's clusters even complete their protostar stage.

Generally speaking, how does the surface temperature and luminosity of a protostar compare to the surface temperature and luminosity of the main-sequence star it becomes?

A main-sequence star is hotter and dimmer than it was as a protostar.

Angular momentum plays an important role in star formation. Which of the following characteristics of a protostellar system is probably not strongly affected by the star's angular momentum?

the onset of core hydrogen fusion

Which process is required to allow a gravitationally-collapsing gas cloud to continue to collapse?

The cloud must radiate much of its thermal energy.

Our Sun is considered to be a

low-mass star

Which two processes can generate energy to help a star maintain its internal thermal pressure?

nuclear fusion and gravitational contraction

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