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MAIN SEQUENCE 
Composition is > 98% hydrogen and helium. 
1/3 of the hydrogen is converted to helium. 
MASS 
TIME 
High-mass stars live for one million to tens of millions of years 
while low-mass stars, like our Sun, live for tens of millions 
to trillions of years. 
GIANT/SUPERGIANT 
Massive stars are capable of producing 
heavier elements, like iron, through fusion. 
SUPERNOVA 
Outer layers of hydrogen and helium are 
ejected along with some heavier elements. 
BLACK HOLE 
A star's core collapses into extremely dense 
matter. Even light cannot escape the 
gravitational pull. 
NEUTRON STAR 
A star's core collapses into a dense mass 
of neutrons. 
MAIN SEQUENCE 
Composition is > 98% hydrogen and helium. 
1/3 of the hydrogen is converted to helium. 
RED GIANT 
Expending hydrogen in their cores, these 
stars extend their outer layers and can grow 
to > 100 times their main sequence size. 
PLANETARY NEBULA 
The outer layers of gas are ejected while 
the star's core contracts into a white dwarf. 
WHITE DWARF 
This star core is typically composed of 
carbon and oxygen. Neon, magnesium, 
and helium are possible. 
BLACK DWARF 
A hypothetical remnant of a cooled white dwarf, 
the Universe's existence is too short to prove 
its existence. 
10–150 solar masses 
90% of lifespan 
Spica, Theta Orionis C 
significant loss of mass 
10% of lifespan 
Betelgeuse, Rigel 
All but 10% of the original mass is ejected 
seconds 
Cassiopeia A, Kepler's Supernova 
3 solar masses or larger 
1070 years 
Cygnus X-1, Sagittarius A 
1.4–3 solar masses 
1033–1045 years 
Circinus X-1, The Mouse 
.08–10 solar masses 
90% of lifespan 
Sun, Altair 
99% of original mass 
10% of lifespan 
Aldebaran, Arcturus 
All but 5-15 % of the original mass is ejected 
tens of thousands of years 
M27, NGC 40 
5%–15% of original mass 
1015 - 1025 years 
Mira B, Sirius B 
< 1.4 solar masses 
1033–1045 years 
HIGH 
MASS STARS 
OR 
BORN IN NEBULAE 
Gas clouds collapse and 
matter accumulates on 
a protostar. 
LOW 
MASS STARS 
RETURN TO NEBULAE 
Matter expelled from stars can 
eventually accumulate into 
new star-forming nebulae. 
THE LIFE CYCLES OF STARS

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Life Cycles of the Stars

  • 1. MAIN SEQUENCE Composition is > 98% hydrogen and helium. 1/3 of the hydrogen is converted to helium. MASS TIME High-mass stars live for one million to tens of millions of years while low-mass stars, like our Sun, live for tens of millions to trillions of years. GIANT/SUPERGIANT Massive stars are capable of producing heavier elements, like iron, through fusion. SUPERNOVA Outer layers of hydrogen and helium are ejected along with some heavier elements. BLACK HOLE A star's core collapses into extremely dense matter. Even light cannot escape the gravitational pull. NEUTRON STAR A star's core collapses into a dense mass of neutrons. MAIN SEQUENCE Composition is > 98% hydrogen and helium. 1/3 of the hydrogen is converted to helium. RED GIANT Expending hydrogen in their cores, these stars extend their outer layers and can grow to > 100 times their main sequence size. PLANETARY NEBULA The outer layers of gas are ejected while the star's core contracts into a white dwarf. WHITE DWARF This star core is typically composed of carbon and oxygen. Neon, magnesium, and helium are possible. BLACK DWARF A hypothetical remnant of a cooled white dwarf, the Universe's existence is too short to prove its existence. 10–150 solar masses 90% of lifespan Spica, Theta Orionis C significant loss of mass 10% of lifespan Betelgeuse, Rigel All but 10% of the original mass is ejected seconds Cassiopeia A, Kepler's Supernova 3 solar masses or larger 1070 years Cygnus X-1, Sagittarius A 1.4–3 solar masses 1033–1045 years Circinus X-1, The Mouse .08–10 solar masses 90% of lifespan Sun, Altair 99% of original mass 10% of lifespan Aldebaran, Arcturus All but 5-15 % of the original mass is ejected tens of thousands of years M27, NGC 40 5%–15% of original mass 1015 - 1025 years Mira B, Sirius B < 1.4 solar masses 1033–1045 years HIGH MASS STARS OR BORN IN NEBULAE Gas clouds collapse and matter accumulates on a protostar. LOW MASS STARS RETURN TO NEBULAE Matter expelled from stars can eventually accumulate into new star-forming nebulae. THE LIFE CYCLES OF STARS