To Help You Review: A Synopsis of the Evolutionary Stages of Our Sun

We've seen that stars can be loosely grouped into 3 different categories based on mass, "Low, Medium, and High". The energy generation and evolutionary stages of each of these stars is quite different, as well as their lifetimes on the main sequence.

Here are three tables, listing randomly all of the possible evolutionary stages, energy sources, and dynamic characteristics of stars.

Stages (Each star type will go through SOME of these, in order. But not every type of star will do all of these!)	Neutron Star	Protostar	Main Sequence G Star
	Planetary Nebula	Main Sequence M Star	Supernova
	Supergiant	Nova	White Dwarf
	Main Sequence O Star	Red Giant	Black Hole

Energy Sources (match these to particular stages)	Hydrogen fusion	Gravitational Contraction	Silicon Fusion to Iron
	Cheerios & Peanut Butter	Helium fusion	None
	Thermal (Heat) Energy only		Carbon fusion

Dynamic Characteristics (match these to particular stages)	In Hydrostatic Equilibrium	Contracting (not stable)	Supported by  Neutron Degeneracy
	Supported by Electron Degeneracy	Dead	Expanding (not stable)

Can you arrange FOR EACH TYPE OF STAR (low, medium, and high mass) the correct stages of evolution, energy sources, and characteristics in their proper order? Note that some of the energy sources and characteristics should be used simultaneously, and some used multiple times. And to make it interesting, some of the stages and energy sources listed are not used for our star!

Directions:

For the particular types of stars listed, start with the first identifiable stage in their evolution in the left-most column. For that stage, select the energy source we believe to be powering that object from the center column. And finally, what is the dynamic characteristic describing the object in that stage? I've put a few examples into the tables for you!

Example:

For a main sequence K star ( stage 2 of its stages as a small star), you might describe its energy source as hydrogen fusion to helium (e2: the energy source for that stage), and its dynamic characteristic (c2) as hydrostatic equilibrium.

HINTS:

• Each Star will have multiple stages! Start with the first step EVERY star goes through...
• Each particular stage will always be matched to the same energy source and dynamic characteristic, so once you identify those matching pieces for one star, they should work together IF they appear in another star.
• All stars do the same thing on the main sequence! So regardless of their main sequence classification (OBAFGKM), their energy source and characteristics should be the same!

Now using the above, complete the evolutionary stages for each type of star listed below. In other words, fill out the blanks for each of the unlabeled stages (s1 - s6), unlabeled energy sources (e1-e6), and unlabeled characteristics (c1-c6),

For our star, the SUN:

For a much smaller star, with fewer stages

For a much LARGER star, with many more stages!

sh 11/09

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