The “Life” of Non-living The “Life” of Non-living StarsStars

By Erin BelluominiBy Erin Belluomini

Why do stars look different colors in Why do stars look different colors in the night sky?the night sky?

Stars are different colorsStars are different colorsColors indicates the temperature of the Colors indicates the temperature of the

starstarRed stars are the coolestRed stars are the coolestBlue stars are the hottestBlue stars are the hottest

Fascinating ExamplesFascinating Examples

Orion is a well-known winter constellationOrion is a well-known winter constellationOrion contains a large red star known as Orion contains a large red star known as

BetelgeuseBetelgeuseOrion also contains a blue star known as Orion also contains a blue star known as

RigelRigelBetelgeuse and Rigel differ in their Betelgeuse and Rigel differ in their

temperatures tootemperatures too

From what elements are stars From what elements are stars created?created?

Studying light from a star can tell us what Studying light from a star can tell us what elements are in starselements are in stars

A continuous spectrum shows all the A continuous spectrum shows all the colors when white light passes through a colors when white light passes through a prismprism

Elements emitted from stars do not show Elements emitted from stars do not show all the colors of the spectrum all the colors of the spectrum

The colors that get absorbed tell scientists The colors that get absorbed tell scientists from what elements the star is madefrom what elements the star is made

Common Elements of StarsCommon Elements of Stars

Hydrogen and Helium are the most Hydrogen and Helium are the most abundant elements in starsabundant elements in stars

Stars contain other trace elementsStars contain other trace elementsCarbon, nitrogen and oxygen are the most Carbon, nitrogen and oxygen are the most

commoncommon

How do scientists classify stars? How do scientists classify stars?

Originally stars were classified by the Originally stars were classified by the elements they containedelements they contained

Astronomers created system based on Astronomers created system based on brightness…absolute magnitudebrightness…absolute magnitudePositive #s are dim, negative #s are brightPositive #s are dim, negative #s are bright

Stars are classified by temperatureStars are classified by temperature

Why do we see different constellations throughout the year?

• Earth revolves around sun• Earth’s tilt and revolution cause season’s • Earth faces a different part of sky each season• A different constellation is seen at different times

of the year

Motion of and Distance to StarsMotion of and Distance to Stars

Stars closer to Earth seem to moveStars closer to Earth seem to move Stars further away seem to stay in one placeStars further away seem to stay in one place Known as parallaxKnown as parallax Parallax used to calculate actual distances to Parallax used to calculate actual distances to

starsstars Distance measured in light-yearsDistance measured in light-years A light-year is the distance light travels in one A light-year is the distance light travels in one

year….very fast!year….very fast!

Our Sun’s Color and Classification

• Our sun is Earth’s closest star

• Our sun’s color is yellow

• Our sun’s temperature is 6000 C

• Hydrogen, Helium, Calcium and other heavier elements make up our sun

• Our sun is a class G star

• Our sun is about +4.8 in absolute magnitude

Do stars “live” forever?Do stars “live” forever?

Stars do not live foreverStars do not live foreverStars can exist for billions of yearsStars can exist for billions of yearsStars get different classifications as they Stars get different classifications as they

ageageTo stay alive, stars must generate energy To stay alive, stars must generate energy

through nuclear fusionthrough nuclear fusion

Nuclear FusionNuclear Fusion

How the sun generates energyHow the sun generates energyProcess where two hydrogen nuclei fuse Process where two hydrogen nuclei fuse

to form heliumto form heliumThe beginning of a stars life The beginning of a stars life

Click to view video clip!

The Life Cycle of StarsThe Life Cycle of Stars

Stars begin life as a ball of gas and dustStars begin life as a ball of gas and dustTemperatures reach 10,000,000 CTemperatures reach 10,000,000 CNuclear Fusion begins Nuclear Fusion begins This stage known as a ProtostarThis stage known as a Protostar

Main SequenceMain Sequence

Main Sequence is the second and longest Main Sequence is the second and longest stage of a star’s lifestage of a star’s lifeHydrogen continues to fuse into heliumHydrogen continues to fuse into heliumSize of star changes very little during this Size of star changes very little during this

stagestage

Giants and SupergiantsGiants and Supergiants

Giants and Supergiants result when a star Giants and Supergiants result when a star uses all the hydrogen in its coreuses all the hydrogen in its core

Star grows very large and coolsStar grows very large and cools

The H-R Diagram

• An H-R Diagram

Shows relationship between surface temperature and absolute magnitude

Massive Stars

• Use their hydrogen much more quickly than stars like our sun.

• Generate more energy but have shorter lives.

• Meet dramatic deaths as Supernova explosions!

• Become neutron stars, pulsars and maybe black holes.

Our Sun’s Age

• Our Sun was born from a solar nebula.

• Our Sun is about half way through it’s life cycle.

• Our Sun will not live forever!

• How will our Sun die?

The Click of Death

Why We Study StarsWhy We Study Stars

The structure and composition of the The structure and composition of the universe can be learned by studying stars universe can be learned by studying stars and galaxies and their evolution.and galaxies and their evolution.

Understanding the properties of stars Understanding the properties of stars provides us with an understanding of our provides us with an understanding of our sun, which is a star!sun, which is a star!

The properties of the sun affect Earth The properties of the sun affect Earth directly, so it is important to know them.directly, so it is important to know them.

Fun Facts

• The brightest star discovered is at least 150 times as large and probably 40 million times as bright as our sun! (Break out those sunglasses)!

• Sir Isaac Newton was the first to discover that white light is composed of different colors!

Comprehension Question

1) What are the two elements that commonly make up stars?

a) Hydrogen (H) and Oxygen (O)

b) Hydrogen (H) and Helium (He)

c) Helium (He) and Nitrogen (N)

d) Hydrogen (H) and Nitrogen (N)

Correct!

b) Hydrogen and Helium are the most common and abundant elements in stars!

Congratulations you are a Sun God or Goddess!

Incorrect!

Try again! Remember that stars undergo nuclear fusion which means one element fuses to become another! Much energy is released in the process!

Hint: What two elements are close enough to each other on the periodic table to be able to undergo nuclear fusion.

Comprehension Question

2) What will be the next stage of our sun’s life cycle?

a) A white dwarf

b) A pulsar

c) A red giant

d) A protostar

Correct Again!

Our star will become a red giant once all of it’s hydrogen in its core is used, its helium has begun to fuse and the center of the star shrinks. The Sun will grow very large and will cool down!

You are definitely a “STAR” student!

Incorrect!

Remember that currently our star is a main-sequence, average size, yellow star!

Works CitedWorks Cited

My vacation

• Look at this sunset!