Exam 11: Formation and Structure of Stars

How does a gas cloud become hot enough to ignite nuclear reactions?

Stars with masses equal to or less than 1.1 solar masses use the _____________ to convert H into He for their energy source.

Briefly describe the pressure-temperature thermostat in stars.

The proton-proton chain for fusing hydrogen into helium is a much more complicated process than the CNO Cycle for fusing hydrogen into helium.

When a large gas cloud starts to collapse in a free-fall due to gravity, the cloud will ____.

As the protostar contracts gravitationally, it will rotate faster and faster and produce a(n) ____.

There are several triggers that could start the gravitational contraction of a molecular cloud and subsequent star formation.  List two of these triggers.

How do large mass stars in the upper region of the main sequence produce energy?

One of the factors that a large molecular cloud must overcome in order for gravitational contraction to begin is rotation of the gas cloud.

Hydrostatic equilibrium in a newborn star is regulated by a very unique thermostat called the _____________ thermostat.

One trigger that could start the gravitational contraction of a molecular cloud to form stars is a passing shock wave.

Four of following are factors that must be overcome by a large molecular cloud before gravitational contraction can begin. Which one is the exception?

How do low mass stars in the lower region of the main sequence produce their energy?

Which trigger could start the gravitational contraction of a molecular cloud?

A protostar will continue to collapse due to gravity until it reaches the main sequence, and then gravitational collapse will stop when _____ begins.

The temperature at the core of a star must be at least 1 million degrees Kelvin before fusion can begin.

Describe the concept of a "birth line" and identify where it falls on the H-R Diagram.

Pre-main sequence stars (not protostars) on the H-R Diagram are _____.

Energy flows by radiation or convection inside normal stars but almost never by _____________ because radiation or convection is much more efficient.