Exam 9: The Formation and Structure of Stars

Energy transport by ____________________ is important when photons cannot readily travel through a gas.

What is hydrostatic equilibrium and how is it used to explain the internal stability of a star?

What is the lifetime of a 10-solar-mass star on the main sequence?

The dust in the interstellar medium can make distant stars look redder than they really are.

Some massive stars only live a few million years.

Due to the dust in the interstellar medium, a distant star will appear to an observer on Earth to be

The pressure of a gas depends on the temperature and density of the gas.

Some young star clusters contain large numbers of T Tauri stars.

What causes the outward gas pressure that balances the inward pull of gravity in a main-sequence star?

Absorption lines due to the interstellar medium indicate that some components of the interstellar medium are cold and of a very low density because

____________________ is the resistance of a gas to the flow of radiation.

How does the method of energy generation inside main-sequence stars affect their internal structure?

The sun makes most of its energy by the CNO cycle.

What observations indicate the presence of dust in the interstellar medium?

Explain what keeps the nuclear reactions in a star under control; i.e., what would happen if too large an amount of energy is released in the center?

The condition of ____________________ means that the force due to gravity pushing down on a layer is exactly equal to the pressure pushing outward on that layer.

____________________ appear reddish in color due to the light emitted by the Balmer series of the hydrogen atom.

Molecular clouds are mapped using CO instead of hydrogen because CO is much more abundant than hydrogen in molecular clouds.

In the collapse of a protostar ____________________ energy is converted to ____________________ energy.

The lowest-mass object that can initiate thermonuclear fusion of hydrogen has a mass of about