Download Life Cycle of Stars

• The "Fingerprints" of Stars
• The best tool we have for studying a star's light
is the star's spectrum. A spectrum (the plural is
"spectra") of a star is like the star's fingerprint.
Just like each person has unique fingerprints,
each star has a unique spectrum. Spectra can
be used to tell two stars apart, but spectra can
also show what two stars have in common.
• The spectrum of a star is similar to the spectrum
of colors you see in rainbows. Stars give off light
in a range of different colors. The spectrum of
visible light - the spectrum you see in a rainbow is shown below.
Life Cycle of Stars
Cat’s Eye Nebula
Nebula
• Giant cloud of Gas and Dust
• Protostar – the force of gravity pulls
hydrogen gas together and it begins to
spin
Main Sequence
• Hydrogen in the core is converted into
Helium by nuclear fusion
• Once fusion occurs, the star begins to
shine or glow
• Hydrogen + Hydrogen = Helium + lots of
energy
• http://www.cnn.com/2015/02/16/tech/nasasolar-dynamics-observatory/index.html
• Solar flares and such on our sun
Red Giants
• All the hydrogen has fused to helium. The
Helium in the core of the star is still burning hot.
Helium starts fusing together to create Carbon or
Oxygen.Gravity keeps contracting the core to
maintain equilibrium, and as the core contracts
the atoms are packed together even tighter than
before. The outer shell has expanded in an effort
to help heat from the core escape into space.
The red giant is the first step in old age.
Red Giant
•
•
•
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Hydrogen in core begins to run out
Core becomes unstable and contracts
Outer core expands
Cools and glows red
• Aldebaran is a K5III star, which means
it is orangish, large, and has moved
off the main sequence after
exhausting the hydrogen fuel in its
core. It has a minor companion (a dim
M2 dwarf orbiting at several hundred
AU). Now primarily fusing helium, the
main star has expanded to a diameter
of 44.2 times the diameter of the Sun,
http://www.stumbleupon.com/su/2r0uXz/postimage.org/image/5xhh7ozes
Length of life of star is
determined by
• MASS
Low to medium mass star
• A low to medium mass star will become a
white dwarf
White Dwarf
• Last of the helium atoms in core are fused
into carbon atoms
• Star begins to die
• Star collapses and is extremely dense
• Ultraviolet light makes the material glow
Black Dwarf
• Once energy is gone, the star will no
longer emit light.
• The star will remain like this forever
Massive stars
• After the red giant phase, a massive star
will undergo a supernova explosion.
• Supernova explosion - a release of energy
when fusion of the atoms stop
Supernovas
• http://www.wimp.com/timelapsesupernova/
If the remnant of the explosion is 1.4 to
about 3 times as massive as our Sun, it
will become a neutron star.
Pulsar
• Is a Rotating Neutron Star
If more massive than 8 times the
mass of the sun
• Gravity finally wins and compresses
everything to a mathematical point at the
center. The point mass is a black hole.
Only the most massive, very rare stars
(greater than 10 solar masses) will form a
black hole when they die
Red Supergiant star – Massive, will become a
black hole someday!!
STAR FORMATION
• Gravity causes clouds of gas and
dust (nebula) to contract until nuclear
fusion of light elements into heavy
ones occur
• Once fusion occurs, the star glows
• http://www.stumbleupon.com/su/2r0uXz/po
stimage.org/image/5xhh7ozes