Exam 9: The Formation and Structure of Stars

What force(s) are responsible for the collapse of an interstellar cloud?

Most stars generate their energy by the thermonuclear fusion of ____________________ to form ____________________.

Protostars are difficult to observe because

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

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

The above visual wavelength image is of a ___________, which is a(n) _________.

If the Sun ceased to generate nuclear fusion in its core, the Sun would immediately begin to collapse inward.

Which of the following energy transport processes involves mass motions of material?

If in a gas the opacity is high, then energy transport is by _____________.

As a star begin to form the initial energy source is from

Which of the following in not a factor that prevents molecular cloud contraction?

The interstellar medium is made of ______________.

Emission nebulae are also called ________ because they are composed of ionized hydrogen.

The above image is an example of a/an _________ nebula.

The creation of ________ require(s) that a young hot star (T ≈ 25,000 K) be relatively nearby.

Convection is important in stars because it

What causes the outward pressure that balances the inward pull of gravity in a star?

Pre-main-sequence stars are above and to the right of the main sequence.

A spectral line produced in the atmosphere of a star may be seen as broad whereas interstellar _______________ lines are very narrow.

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