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After the Sun's core hydrogen is depleted by
nuclear fusion the core will consist primarily of
1) carbon.
2) deuterium.
3) helium.
4) oxygen.
The material that makes up the Sun was once
part of
1) the Big Bang.
2) another star.
3) a molecular cloud.
4) all of the above.
Most of the brightest stars in the sky are
1) relatively hot small stars.
2) relatively cool giant stars.
3) relatively cool small stars.
4) relatively hot giant stars.
Ejnar Hertzsprung
Henry Norris Russell
Hertzsprung–
Russell
diagram
http://www.universetoday.com/wp-content/uploads/2009/02/hrdiagram.jpg
Hertzsprung–
Russell
diagram
http://upload.wikimedia.org/wikipedia/commons/6/6b/HRDiagram.png
A main sequence star is stable because of
self-regulation;
1) the nuclear reaction rate does not
depend on temperature.
2) a slight contraction leads to higher gas
pressure.
3) a slight contraction decreases the
nuclear reaction rate.
4) a slight contraction leads to lower
internal pressure.