Exam 9: The Formation and Structure of Stars

Why do nuclear reactions in a star occur only near its center

The hottest star in the Orion Nebula ____________hydrogen gas and makes it _____________.

Ninety percent of all stars fuse helium to form carbon and lie on the main sequence.

If a star's pressure increases in its interior to push the star outward, its temperature will drop, causing the star to contract and eventually return to equilibrium.

________ are small dark nebulae about 1 light-year in diameter that contain 10 to 1,000 solar masses.

ZAMS is an acronym for ______________________________.

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

The free-fall contraction of a molecular cloud

How long a star can remain on the main sequence depends upon its __________.

Stars are born in ______________________.

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

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

Of the two colors shown in the image above, the pink colored nebula is the least common.

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

Protostars are in hydrostatic equilibrium.

Interstellar gas clouds may collapse to form stars if they

A jet has an angular length of 10 seconds of arc and flows from a star at a distance of 2,000 pc. How far does this jet extend away from the star

If a star's temperature increases in its interior, then more nuclear reactions will occur to push the star outward and its temperature will drop, causing the star to contract and eventually return to equilibrium.

The above image shows stars behind a cloud.

A star on the ____________________ generates enough energy from nuclear fusion to halt gravitational collapse.