Transcript LIFE CYCLE OF A STAR

Astronomy
7th Grade
Chapter 2.2
The Beginning and End of
Stars
 A star enters the first stage of its life cycle as a ball of
gas and dust.
 As this ball of gas becomes denser, it gets hotter and
changes to helium – __________________.
 As stars age, they lose some of their material.
 When a star dies, they could explode in the form of a
____________________.
DIFFERENT TYPES OF
STARS
 Stars can be classified by their:
Size
Mass
Brightness
Color
Temperature
Spectrum
Age
PROTOSTAR:
A Star is Born
 Born in a Nebula: an _____________and
other _______________.
 A Baby Star
 ________ in Color
 Forms over _______ of years
MAIN SEQUENCE
 Second and ____________ stage of a star’s life cycle
 Energy is generated in the core of the star.
 Hydrogen atoms fuse into Helium atoms.
 This process releases an ENORMOUS amount of
Energy.
GIANTS and
SUPERGIANTS
 Third Stage of Life Cycle
 RED GIANT: a star that _________ and
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___________once it uses all of its hydrogen.
The loss of hydrogen causes the center of the star to
_________________.
The atmosphere of the star grows very _______ and
_______________ to form this RED GIANT!
Red Giants: 10x bigger than the Sun.
Super Giants: 100 x bigger than the Sun
WHITE DWARFS
 FINAL stage of a star’s life cycle.
 Has same mass as the sun or smaller
 White Dwarf: small, hot star that is the leftover center
of an older star
 NO _______________ LEFT!
 NO LONGER CAN GENERATE __________
by fusing hydrogen atoms into _____ atoms.
 Can shine for _____________of years even after they
die.
SUPERNOVAS
 Supernova: A gigantic ____________ in which a
massive star collapses and throws its outer layers
into space.
 This explosion powerful that it could be brighter
than an entire galaxy for days!
NEUTRON STARS
 After a Supernova, the center of the collapsed star
contracts to form a new star.
 The mass of the new star is about 2x the mass of the
Sun – WOW!
 A star has collapsed under gravity to the point where
all the star particles are NEUTRONS.
PULSARS
 If a neutron star is ____________, it is called a
PULSAR.
 A PULSAR sends out a beam of __________.
 The beam is detected on Earth by telescopes as rapid
clicks, or pulses (hence – PULSAR).
BLACK HOLES
 If the center of a collapsed star has a mass more than 3x the
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mass of the sun, the star may contract.
The 3x star contracts because of the strength of its gravity.
The force of the contraction CRUSHES the dense center of
the star.
It leaves a BLACK HOLE.
BLACK HOLE: An object that is so massive that light
cannot escape its gravity. WOOH!