CHAPTER 9 :STARS AND GALAXIES

Prepared by :Pn. Noor Hazwani bt.AliasSMK Sg.Maong,Kuching

The Sun

The Sun

- Shape like a ball.

- Made up of hot gases : hydrogen and helium

- Surface temperature : 5 500 - 6 000 oC

- The Sun is one of the many billions of stars.

- Nearest star to Earth. That is why it appears bigger and brighter than other stars.

Has Has three layersthree layers

Structure of the Sun

Corona Chromosphere

Photosphere

can only be seen clearly during solar eclipse.

can be seen clearly everyday

Solar eclipseSolar eclipse

Corona and Chromosphere can only be seen during solar eclipse.

Corona Chromosphere

Phenomena on The Surface of The SunPhenomena on The Surface of The Sun

Prominence-arches or loops shape.-eruption of chromosphere(2nd layer)

Solar flare- explosion near sunspots- release charged particles into outer space. (Examples: * Electrons, * X-rays, * Ultraviolet rays)

Sunspot- cool spot - eruption of photosphere(1st layer)

AuroraAurora Dazzling,colourful light.Dazzling,colourful light. Occur at Occur at north pole north pole and and south pole south pole of Earth.of Earth. Charged particles interact with Earth’s magnetic Charged particles interact with Earth’s magnetic

field.field.

Solar flare-release charged particles (Examples: * Electrons, * X-rays, * Ultraviolet rays)

How the Sun produces energy?How the Sun produces energy?

Nuclear reaction (in the core)Nuclear reaction (in the core) 4 hydrogen atoms 4 hydrogen atoms 1 helium atom + light energy + heat energy 1 helium atom + light energy + heat energy

+Light and

heat energy

Various types of StarVarious types of Star

SizeSize

Temperature and colourTemperature and colour

Various types of StarVarious types of Star

BlueHottest star

YellowMedium temperature

RedCoolest star

Colour Temperature Example:

Blue 40 000 0C Spica

Bluish- white

10 000 0C Rigel

Yellow 6 000 0C The Sun

Red 3 000 0C Betelgeuse

Medium temperature

Brightness.Brightness.

Various types of StarVarious types of Star

Rigel

Sirius

Sirius

Rigel

Procyon

Achernar

5 brightest star

Formation of StarsFormation of Stars

Gases(hydrogen)

Dusts

Anebula

A core is formed.-very hot and dense

-The core becomes hotter.- Nuclear reactions take place.

A STAR IS FORMED !!

1.

*Nuclear reaction (in the core)*Nuclear reaction (in the core) 4 hydrogen atoms 4 hydrogen atoms 1 helium atom + light energy + heat energy 1 helium atom + light energy + heat energy

3.

2.

Gases and dusts in a nebula are pulled by strong gravity forces until it become compact (dense).

Death of StarDeath of Star*depends on the size of the star*depends on the size of the star

Nebula

Death of StarDeath of Star*medium size star, such as The Sun*medium size star, such as The Sun

2. *gravity pull weakens. *the star expands and forms red giant.

1. *Hydrogen atoms in the star are all used up. * Nuclear reaction stops.

3. *Substance at the outer part of the star escape to outer space.

4. *A white core or a white dwarf is formed.

Medium size star

Black Dwarf

Death of StarDeath of Star*large star and super large star*large star and super large star

star

* DEATH OF LARGE STAR (10 x Sun’s mass)

* DEATH OF SUPER LARGE STAR (100 x Sun’s mass)

1. *Hydrogen atoms in the star are all used up. * Nuclear reaction stops.

2. * Gravity pull weakens. * The star expands and forms red giant. * The red giant continue to expand to form red supergiant.

3. *Red supergiant explodes. *The explosion is known as supernova.

Nebula

Neutron star Neutron star : :

*consists of neutrons.*consists of neutrons.

*rotates and gives out radio*rotates and gives out radio

waves.waves.

Black HoleBlack Hole: :

*cannot be seen.*cannot be seen.

*dense.*dense.

*has very strong gravity force.*has very strong gravity force.

ConstellationConstellation A group of stars A group of stars arranged in arranged in specific pattern.specific pattern.

In the past, constellation were used as : In the past, constellation were used as :

a) a) compass compass (to show direction).(to show direction).

b) b) calendercalender

A constellation

ConstellationConstellation

North

Big dipper

Examples :

South

North

Southern cross

Universe and GalaxiesUniverse and Galaxies

Universe

Galaxies

Solar System

Earth

Human being

Milky Way(our galaxy)

*Notes

The Universe :-a very huge space-holds everything from the smallest particle to the largest galaxy.-there are billions of galaxies in the Universe.

Galaxy :-Each galaxy has billions of stars.

Hubble Space TelescopeHubble Space Telescope-is used to observe galaxies-is used to observe galaxies

GalaxiesGalaxies

Spiral galaxy Irregular galaxy(no obvious shape)

Elliptical galaxy(oval shape)

- A galaxy contains billions of stars.- Has many shapes.

Our Galaxy : The Milky WayOur Galaxy : The Milky Way

Spiral shape