The particular manner in which a star evolves depends most strongly upon its <1>. This can easily be seen by noting the time it takes protostars to reach the main sequence and the length of time that stars live on the main sequence. A $starMass star will live a <2> main sequence life than the sun will live.
Objects that have insufficient mass to become stars are known as <3>. Stars with masses slightly greater than 0.08 solar masses are known as <4>. These stars are long-lived because they burn their hydrogen conservatively and because their primary mechanism for thermal transport is <5>. Thus they cannot run out of hydrogen in the core, they must run out in the entire star. All of the red dwarfs that have ever lived are still on the main sequence.
A star like the sun will run out hydrogen in its core. When this occurs its primary energy source will be a shell fusing H into He and it will leave the main sequence and expand to become a <6>. This is described by Stellar Evolution Law <7>. The core of He will then continue to contract until temperatures of 100,000,000 K are reached and He starts fusing into C (and O) in the core. The star will now move back toward the main sequence to an area of the HR Diagram known as the <8> where it is stable for a long period of time. Eventually the star will run out of He in the core and the fusion region will move outward expanding the star into a red giant again. This second time the star is even larger than the first. The outer regions of the star are now blown off in what is known as a <9>. The remaining core of C (and O) becomes what is known as a <10>, an object that can be thought of as similar to an ember from a fire -- it isn't burning anymore but is slowly cooling down.
@ qu.1.1.algorithm= $num1 = rint(2); $starMass = switch($num1,"10 solar mass","0.1 solar mass"); $goodTime = switch($num1,"much shorter", "much longer"); $badTime = switch($num1,"much longer","much shorter"); @ qu.1.1.blank.1=mass,luminosity,surface temperature,composition@ qu.1.1.blank.2=$goodTime,$badTime@ qu.1.1.blank.3=brown dwarfs,red dwarfs,white dwarfs,black dwarfs@ qu.1.1.blank.4=red dwarfs,brown dwarfs,white dwarfs,black dwarfs@ qu.1.1.blank.5=convection, radiation, conduction@ qu.1.1.blank.6=red giant, white dwarf, yellow giant, red dwarf@ qu.1.1.blank.7=#1,#2,#3@ qu.1.1.blank.8=horizontal branch, white dwarf region, red dwarf region, black dwarf region@ qu.1.1.blank.9=planetary nebula, supernova, yellow giant, red giant@ qu.1.1.blank.10=white dwarf, red dwarf, brown dwarf, black dwarf@ qu.1.1.grader.1=menu@ qu.1.1.grader.2=menu@ qu.1.1.grader.3=menu@ qu.1.1.grader.4=menu@ qu.1.1.grader.5=menu@ qu.1.1.grader.6=menu@ qu.1.1.grader.7=menu@ qu.1.1.grader.8=menu@ qu.1.1.grader.9=menu@ qu.1.1.grader.10=menu@ qu.1.2.mode=Blanks@ qu.1.2.editing=useHTML@ qu.1.2.name=Stellar Evolution 1@ qu.1.2.question=The particular manner in which a star evolves depends most strongly upon its <1>. This can easily be seen by noting the time it takes protostars to reach the main sequence and the length of time that stars live on the main sequence. A $starMass star will live a <2> main sequence life than the sun will live.
Objects that have insufficient mass to become stars are known as <3>. Stars with masses slightly greater than 0.08 solar masses are known as <4>. These stars are long-lived because they burn their hydrogen conservatively and because their primary mechanism for thermal transport is <5>. Thus they cannot run out of hydrogen in the core, they must run out in the entire star. All of the red dwarfs that have ever lived are still on the main sequence.
A star like the sun will run out hydrogen in its core. When this occurs its primary energy source will be a shell fusing H into He and it will leave the main sequence and expand to become a <6>. The core of He will then continue to contract until temperatures of 100,000,000 K are reached and He starts fusing into C (and O) in the core. This is described by Stellar Evolution Law <7>. The star will now move back toward the main sequence to an area of the HR Diagram known as the <8> where it is stable for a long period of time. Eventually the star will run out of He in the core and the fusion region will move outward expanding the star into a red giant again. This second time the star is even larger than the first. The outer regions of the star are now blown off in what is known as a <9>. The remaining core of C (and O) becomes what is known as a <10>, an object that can be thought of as similar to an ember from a fire -- it isn't burning anymore but is slowly cooling down.
@ qu.1.2.algorithm= $num1 = rint(2); $starMass = switch($num1,"10 solar mass","0.1 solar mass"); $goodTime = switch($num1,"much shorter", "much longer"); $badTime = switch($num1,"much longer","much shorter"); @ qu.1.2.blank.1=mass,luminosity,surface temperature,composition@ qu.1.2.blank.2=$goodTime,$badTime@ qu.1.2.blank.3=brown dwarfs,red dwarfs,white dwarfs,black dwarfs@ qu.1.2.blank.4=red dwarfs,brown dwarfs,white dwarfs,black dwarfs@ qu.1.2.blank.5=convection, radiation, conduction@ qu.1.2.blank.6=red giant, white dwarf, yellow giant, red dwarf@ qu.1.2.blank.7=#2,#1,#3@ qu.1.2.blank.8=horizontal branch, white dwarf region, red dwarf region, black dwarf region@ qu.1.2.blank.9=planetary nebula, supernova, yellow giant, red giant@ qu.1.2.blank.10=white dwarf, red dwarf, brown dwarf, black dwarf@ qu.1.2.grader.1=menu@ qu.1.2.grader.2=menu@ qu.1.2.grader.3=menu@ qu.1.2.grader.4=menu@ qu.1.2.grader.5=menu@ qu.1.2.grader.6=menu@ qu.1.2.grader.7=menu@ qu.1.2.grader.8=menu@ qu.1.2.grader.9=menu@ qu.1.2.grader.10=menu@