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Life Cycle of a Star

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Page 1: Life Cycle of a Star - images.pcmac.orgimages.pcmac.org/.../Documents/PwrPt_Life_Cycle_of_Stars.pdf · Life Cycle of a Star . The Night Sky ... While a stars life span depends on

Life Cycle of a Star

Page 2: Life Cycle of a Star - images.pcmac.orgimages.pcmac.org/.../Documents/PwrPt_Life_Cycle_of_Stars.pdf · Life Cycle of a Star . The Night Sky ... While a stars life span depends on

The Night Sky

Ancient observers around the world looked up at

the night sky and imagined groups of starts

formed pictures. We call these imaginary

patterns of stars constellations.

Big Dipper

Orion’s Belt

Page 3: Life Cycle of a Star - images.pcmac.orgimages.pcmac.org/.../Documents/PwrPt_Life_Cycle_of_Stars.pdf · Life Cycle of a Star . The Night Sky ... While a stars life span depends on

Classifying Stars

A star is a ball of plasma held together by its own gravity.

Characteristics used to classify stars include color, temperature, size, composition, and brightness.

Ant’s Nebula

Page 4: Life Cycle of a Star - images.pcmac.orgimages.pcmac.org/.../Documents/PwrPt_Life_Cycle_of_Stars.pdf · Life Cycle of a Star . The Night Sky ... While a stars life span depends on

Twinkle, Twinkle, Little Star ...

Page 5: Life Cycle of a Star - images.pcmac.orgimages.pcmac.org/.../Documents/PwrPt_Life_Cycle_of_Stars.pdf · Life Cycle of a Star . The Night Sky ... While a stars life span depends on

How I Wonder What You Are ...

Stars have Different colors which

indicate different temperatures.

The hotter a star is, the faster it burns its

life away.

O, B, A, F, G, K, M [Oh Be A Feisty Goat, Kick Me]

Page 6: Life Cycle of a Star - images.pcmac.orgimages.pcmac.org/.../Documents/PwrPt_Life_Cycle_of_Stars.pdf · Life Cycle of a Star . The Night Sky ... While a stars life span depends on

Characteristics of Stars

A stars magnitude (brightness) depends

upon both its size and temperature.

A stars apparent magnitude is how bright a

star appears to be from Earth

A stars absolute magnitude (luminosity) is

how bright a star actually is.

Swan Nebula Light Echo

Page 7: Life Cycle of a Star - images.pcmac.orgimages.pcmac.org/.../Documents/PwrPt_Life_Cycle_of_Stars.pdf · Life Cycle of a Star . The Night Sky ... While a stars life span depends on

Characteristics of Stars

Astronomers use a unit called a light-year to

measure distances between the stars.

In space, light travels at about 186,000 miles per

second.

A light year is the distance that light would travel in a

year or 6,000,000,000,000 (6 trillion) miles.

Page 8: Life Cycle of a Star - images.pcmac.orgimages.pcmac.org/.../Documents/PwrPt_Life_Cycle_of_Stars.pdf · Life Cycle of a Star . The Night Sky ... While a stars life span depends on

Measuring Objects in Space

Astronomers use parallax

to measure distances. A

parallax is the apparent

chance in position of an

object when you look at it

from a different place.

Page 9: Life Cycle of a Star - images.pcmac.orgimages.pcmac.org/.../Documents/PwrPt_Life_Cycle_of_Stars.pdf · Life Cycle of a Star . The Night Sky ... While a stars life span depends on

Hertzsprung-Russell Diagram L

um

ino

sity

Temperature

An H-R diagram

plots the

luminosity and

temperature of

stars.

Page 10: Life Cycle of a Star - images.pcmac.orgimages.pcmac.org/.../Documents/PwrPt_Life_Cycle_of_Stars.pdf · Life Cycle of a Star . The Night Sky ... While a stars life span depends on

Life of a Star

Four types of stars make up the life of

a star

Nebulas

Main Sequence

Giants & Super Giants

White Dwarfs

Page 11: Life Cycle of a Star - images.pcmac.orgimages.pcmac.org/.../Documents/PwrPt_Life_Cycle_of_Stars.pdf · Life Cycle of a Star . The Night Sky ... While a stars life span depends on

Stellar Nursery – 1st Stage

Stars begin as clouds of gas and dust called Nebulas that are pulled together by gravity.

Matter in the gas cloud will begin to condense into a dense region called a protostar.

Cat’s Eye Nebula Cone Nebula

Page 12: Life Cycle of a Star - images.pcmac.orgimages.pcmac.org/.../Documents/PwrPt_Life_Cycle_of_Stars.pdf · Life Cycle of a Star . The Night Sky ... While a stars life span depends on

Main Sequence – 2nd Stage

Nuclear Fusion begins as the gas cloud becomes hotter and denser beginning the main sequence phase.

While a stars life span depends on its size and temperature, it will spend most of its life in this phase.

Our Sun is currently in

the main sequence

phase.

Page 13: Life Cycle of a Star - images.pcmac.orgimages.pcmac.org/.../Documents/PwrPt_Life_Cycle_of_Stars.pdf · Life Cycle of a Star . The Night Sky ... While a stars life span depends on

Red Giants and Supergiants

Eventually, the star's fuel will begin to run out. It will expand into what is known as a red giant. Massive stars will become red supergiants.

This phase will last until the star exhausts its remaining fuel (hydrogen) at this point the star will collapse.

Page 14: Life Cycle of a Star - images.pcmac.orgimages.pcmac.org/.../Documents/PwrPt_Life_Cycle_of_Stars.pdf · Life Cycle of a Star . The Night Sky ... While a stars life span depends on

Dwarfs

Most average stars will blow away their outer

atmospheres to form a planetary nebula.

Their cores will remain behind and burn as a

white dwarf until they cool down and all that is

left is a dark ball of matter known as a black

dwarf.

Page 15: Life Cycle of a Star - images.pcmac.orgimages.pcmac.org/.../Documents/PwrPt_Life_Cycle_of_Stars.pdf · Life Cycle of a Star . The Night Sky ... While a stars life span depends on

Massive Stars

If the star is massive enough, the collapse will trigger a violent explosion known as a supernova.

Material from the star is left behind creating a neutron star made of nothing but neutrons. Neutron stars spin and send out beams of radiation

called pulsars.

Page 16: Life Cycle of a Star - images.pcmac.orgimages.pcmac.org/.../Documents/PwrPt_Life_Cycle_of_Stars.pdf · Life Cycle of a Star . The Night Sky ... While a stars life span depends on

Black Holes

If the mass of the star is large enough, it will collapse so completely that it will literally disappear from the universe creating a Black Hole. Even light cannot escape its gravity.

Astronomers can detect black holes by using X-ray telescopes.

Optical X-ray

Page 17: Life Cycle of a Star - images.pcmac.orgimages.pcmac.org/.../Documents/PwrPt_Life_Cycle_of_Stars.pdf · Life Cycle of a Star . The Night Sky ... While a stars life span depends on
Page 18: Life Cycle of a Star - images.pcmac.orgimages.pcmac.org/.../Documents/PwrPt_Life_Cycle_of_Stars.pdf · Life Cycle of a Star . The Night Sky ... While a stars life span depends on

Life Cycle of Stars

black dwarf