1 files changed, 134 insertions, 0 deletions
diff --git a/doc/kstars/stars.docbook b/doc/kstars/stars.docbook
new file mode 100644
index 00000000..777a636c
--- /dev/null
+++ b/doc/kstars/stars.docbook
@@ -0,0 +1,134 @@
+<sect1 id="ai-stars">
+<sect1info>
+<author>
+<firstname>Jason</firstname> <surname>Harris</surname>
+</author>
+</sect1info>
+<title>Stars: An Introductory <acronym>FAQ</acronym></title>
+<indexterm><primary>Stars</primary></indexterm>
+
+<qandaset id="stars-faq">
+
+<qandaentry>
+<question>
+<para>What are the stars?</para>
+</question>
+<answer>
+<para>
+<firstterm>Stars</firstterm> are gigantic, self-gravitating spheres
+of (mostly) Hydrogen gas.  Stars are also thermonuclear engines;
+nuclear fusion takes place deep in the cores of stars, where the
+density is extreme and the temperature reaches tens of millions
+of degrees Celsius.
+</para>
+</answer>
+</qandaentry>
+
+<qandaentry>
+<question>
+<para>Is the Sun a star?</para>
+</question>
+<answer>
+<para>
+Yes, the Sun is a star.  It is the dominant centerpiece of our
+solar system.  Compared to other stars, our Sun is rather ordinary;
+it appears to be so much bigger and brighter to us
+because it is millions of times closer than any other star.
+</para>
+</answer>
+</qandaentry>
+
+<qandaentry>
+<question>
+<para>Why do stars shine?</para>
+</question>
+<answer>
+<para>
+The short answer is: star shine because they are very hot.  It is
+really no more complicated than that.  Any object heated to
+thousands of degrees will radiate light, just like stars do.
+</para>
+</answer>
+</qandaentry>
+
+<qandaentry>
+<question>
+<para>The obvious next question is: why are stars so hot?</para>
+</question>
+<answer>
+<para>
+This is a tougher question.  The usual answer is that stars get
+their heat from the thermonuclear fusion reactions in their cores.
+However, this cannot be the ultimate cause for the stars' heat,
+because a star must be hot in the first place for nuclear fusion to be
+triggered.  Fusion can only sustain the hot temperature; it cannot
+make a star hot.  A more correct answer is that stars are hot because
+they have collapsed.  Stars form from diffuse gaseous nebulae; as the
+nebulous gas condenses to form a star, the gravitational potential
+energy of the material is released, first as kinetic energy, and
+ultimately as heat as the density increases.
+</para>
+</answer>
+</qandaentry>
+
+<qandaentry>
+<question>
+<para>Are stars all the same?</para>
+</question>
+<answer>
+<para>
+Stars have many things in common: they are all collapsed spheres of
+hot, dense gas (mostly Hydrogen), and nuclear fusion reactions are
+occurring at or near the centers of every star in the sky.
+</para><para>
+However, stars also show a great diversity in some properties.
+The brightest stars shine almost 100 million times as brightly as the
+faintest stars.  Stars range in surface temperature from only a few
+thousand degrees to almost 50,000 degrees Celsius.  These differences
+are largely due to differences in mass: massive stars are both hotter
+and brighter than lower-mass stars.  The temperature and Luminosity
+also
+depend on the <emphasis>evolutionary state</emphasis>
+of the star.
+</para>
+</answer>
+</qandaentry>
+
+<qandaentry>
+<question>
+<para>What is the Main Sequence?</para>
+</question>
+<answer>
+<para><indexterm><primary>Main sequence</primary></indexterm>
+The main sequence is the evolutionary state of a star when it is
+fusing Hydrogen in its core.  This is the first (and longest) stage
+of a star's life (not including protostar phases).  What happens to a
+star after it runs out of core Hydrogen is addressed in the stellar
+evolution article (coming soon).
+</para>
+</answer>
+</qandaentry>
+
+<qandaentry>
+<question>
+<para>How long do stars last?</para>
+</question>
+<answer>
+<para>
+The lifetime of a star depends very much on its mass.  More massive
+stars are hotter and shine much more brightly, causing them to
+consume their nuclear fuel much more rapidly.  The largest
+stars (roughly 100 times as massive as the Sun), will run out of
+fuel in only a few million years; while the smallest stars (roughly
+ten percent the mass of the Sun), with their much more frugal
+consumption rate, will shine on (albeit dimly) for
+<emphasis>trillions</emphasis> of years.  Note that this is much
+longer than the Universe has yet been in existence.
+</para>
+</answer>
+</qandaentry>
+
+</qandaset>
+</sect1>
+
+