Stars. Stars Star: a large celestial body that is composed of gas and that emits light.

StarsStars

StarsStars

Star: Star: a large celestial body that is a large celestial body that is composed of gas and that emits light.composed of gas and that emits light.

StarsStars

States of MatterStates of Matter

Temperature is a measure of energyTemperature is a measure of energyLow energy = SolidLow energy = SolidMedium energy = LiquidMedium energy = LiquidHigh energy = GasHigh energy = GasHigher energy = PlasmaHigher energy = PlasmaPlasma gives off light: lightning, flames, Plasma gives off light: lightning, flames,

fluorescent light bulbs, northern lights, fluorescent light bulbs, northern lights, starsstars

NebulaNebulaClouds of gases and dustClouds of gases and dustMostly hydrogenMostly hydrogenBirthplace of stars and solar Birthplace of stars and solar

systemssystems

ProtostarProtostar

Nebula collapses and Nebula collapses and pressure/temperature pressure/temperature buildsbuilds

Fusion BeginsFusion Begins

How a Star WorksHow a Star Works

Nuclear FusionNuclear Fusion

At 15,000,000 At 15,000,000 ooC hydrogen atoms (protons) C hydrogen atoms (protons) fuse to form heliumfuse to form helium

A small amount of matter (solid stuff) is A small amount of matter (solid stuff) is converted into energyconverted into energy

Einstein figured out how much energy: Einstein figured out how much energy:

E = mcE = mc22

Gravitational Gravitational CollapseCollapse

Gas pressure and heat Gas pressure and heat push outwardspush outwards

Gravity pulls inwardGravity pulls inward

EquilibriumEquilibrium(everything equal (everything equal or balanced)or balanced)

New star clears out the nebulaNew star clears out the nebula

StarsStars

The The Hertzsprung-Hertzsprung-

Russell Russell diagramdiagram

(HR Diagram)(HR Diagram)

Light YearLight YearA light year is the distance light travels in A light year is the distance light travels in

one yearone yearLight travels at 186,000 miles each Light travels at 186,000 miles each secondsecondOne light year is 5,869,713,600,000 (thatOne light year is 5,869,713,600,000 (that’’s s

almost 6 almost 6 trilliontrillion miles!) miles!)The sun is 8 light minutes away from The sun is 8 light minutes away from

Earth.Earth.The next The next closestclosest star to Earth is 4 light star to Earth is 4 light

years away.years away.

Dwarf StarsDwarf StarsVariety of Variety of ““colorscolors””. Most common type.. Most common type.

Yellow Dwarf Yellow Dwarf includes our own sunincludes our own sunBrown Dwarf Brown Dwarf – failed stars that never heated – failed stars that never heated

up enough to explode into a normal starup enough to explode into a normal starWhite Dwarf White Dwarf – collapsed stars that are slowly – collapsed stars that are slowly

burning away the last of their fuelburning away the last of their fuelBlack Dwarf Black Dwarf – non-luminous (no light) dead – non-luminous (no light) dead

starsstars

Brown DwarfBrown Dwarf

““AlmostAlmost”” star starBigger than a Jupiter-type planet, smaller Bigger than a Jupiter-type planet, smaller

than a true starthan a true starHot core, but not star-hotHot core, but not star-hotNo (or little) fusionNo (or little) fusion

Red DwarfRed Dwarf

Small, cool starSmall, cool starLongest life span >10,000,000,000 Longest life span >10,000,000,000

(10 billion) years(10 billion) yearsMost numerousMost numerousActive fusion in coreActive fusion in core

Yellow DwarfYellow Dwarf

Our sunOur sunActive fusion in coreActive fusion in coreLifetime about 10,000,000,000 yearsLifetime about 10,000,000,000 yearsOur sun is about 5,000,000,000 oldOur sun is about 5,000,000,000 old

Red GiantRed Giant

After a yellow dwarf burns up its fuel it After a yellow dwarf burns up its fuel it cools and contractscools and contracts

Temperature again rises and the star Temperature again rises and the star expands rapidlyexpands rapidly

Becomes a red giantBecomes a red giantOur sun will be about the size of the Our sun will be about the size of the

EarthEarth’’s orbit (bye bye Mercury, Venus, s orbit (bye bye Mercury, Venus, Earth!)Earth!)

Giants – Super GiantsGiants – Super Giants

GiantsGiants1 thousand times brighter than the sun1 thousand times brighter than the sun200 times larger200 times larger

Super GiantsSuper Giants10 million times brighter10 million times brighterThousands of times largerThousands of times larger

Binary StarsBinary Stars

Two stars orbiting each otherTwo stars orbiting each otherMost common form of stars in the Milky Most common form of stars in the Milky

WayWayJupiter 2 – 3 times more massive, we (doJupiter 2 – 3 times more massive, we (do

nn’’t) exist in a binary star systemt) exist in a binary star system

Binary White Dwarf SystemBinary White Dwarf System

Alpha Centauri – Proxima CentauriAlpha Centauri – Proxima Centauri

EarthEarth’’s next closest neighbor star –s next closest neighbor star –

4 light years away4 light years away

Planetary and Astronomical Planetary and Astronomical ScalesScales

SupernovaSupernovaMassive starsMassive starsRapidly uses up hydrogen, fuses larger Rapidly uses up hydrogen, fuses larger

atomsatomsRequires energy instead of giving off Requires energy instead of giving off

energyenergyStellar collapse causes rapid increase in Stellar collapse causes rapid increase in

pressure and temperaturepressure and temperatureStar explodesStar explodes Inner layers compressed into extremely Inner layers compressed into extremely

tight ball of mattertight ball of matter

SupernovaSupernova

Visible X-ray

Neutron StarNeutron Star

Neutron Star (Super Massive…Heavy!!!)Neutron Star (Super Massive…Heavy!!!)Under collapse, protons and electrons combine Under collapse, protons and electrons combine

to form neutrons.to form neutrons.10 km across10 km across

Black HoleBlack Hole

Mass of core > 5 x Solar massMass of core > 5 x Solar massGravitational force so strong not even light Gravitational force so strong not even light

can collapsecan collapseCenter of most galaxiesCenter of most galaxiesEats other starsEats other starsNot even compacted neutrons can support Not even compacted neutrons can support

weight of very massive starsweight of very massive stars

PulsarsPulsars

Neutron star that emits EM Radiation – Neutron star that emits EM Radiation – radio – gammaradio – gamma

Pulse rotates rapidly causing the signal to Pulse rotates rapidly causing the signal to fade in and outfade in and out

Pulses occur as often as once per secondPulses occur as often as once per second

X-Ray BinariesX-Ray Binaries In close binary systems, material flows from

normal star to Neutron Star or Black Hole. X-rays emitted from disk of gas around Neutron

Star/Black Hole.

Star GroupsStar GroupsConstellations: one of 88 regions into which

the sky has been divided in order to describe the locations of celestial objects; a group of stars organized in a recognizable pattern.

GalaxyGalaxyGalaxy:Galaxy: a collection of stars, dust, and a collection of stars, dust, and

gas bound together by gravity.gas bound together by gravity.

You are here.

GalaxiesGalaxies

Spiral GalaxiesSpiral GalaxiesSpiral Galaxy: Spiral Galaxy: the most common type, the most common type,

where there is a nucleus of bright stars where there is a nucleus of bright stars and a flattened arms that spiral around the and a flattened arms that spiral around the nucleus. The arm consists of young stars, nucleus. The arm consists of young stars, gas, and dust.gas, and dust.

Milky Way = Our GalaxyMilky Way = Our GalaxyAround 100,000,000,000 starsAround 100,000,000,000 starsSpiral GalaxySpiral Galaxy100,000 light years across100,000 light years across

Elliptical GalaxiesElliptical GalaxiesElliptical Galaxies: Elliptical Galaxies: are extremely bright are extremely bright

in the center and do not have spiral arms. in the center and do not have spiral arms. Elliptical galaxies have few young stars Elliptical galaxies have few young stars and contain little dust and gas.and contain little dust and gas.

Irregular GalaxiesIrregular Galaxies Irregular Galaxies: Irregular Galaxies: have low total masses have low total masses

and are fairly rich in dust and gas. (only a and are fairly rich in dust and gas. (only a small percentage of total galaxies)small percentage of total galaxies)

QuasarsQuasarsQuasar: Quasar: quasi-stellar radio source, a very quasi-stellar radio source, a very

luminous object that produces energy at a luminous object that produces energy at a high rate. (very distant objects located in high rate. (very distant objects located in the center of galaxies)the center of galaxies)

The Big Bang TheoryThe Big Bang TheoryCosmology: Cosmology: the study of the origin, the study of the origin,

properties, processes, and evolution properties, processes, and evolution of of the universe.the universe.

Hubble Space Telescope ResearchHubble Space Telescope Research

The Hubble Telescope The Hubble Telescope allowed researches allowed researches to see that hundreds of galaxies have to see that hundreds of galaxies have large red shiftslarge red shifts; therefore, they are moving ; therefore, they are moving away from earth away from earth very fast.very fast.

The Universe is Expanding!The Universe is Expanding!

The Big Bang TheoryThe Big Bang TheoryBig Bang Theory: Big Bang Theory: the theory that all matter the theory that all matter

and energy in the universe was compressed and energy in the universe was compressed into an extremely small volume that 13 to 15 into an extremely small volume that 13 to 15 billion years ago exploded and began billion years ago exploded and began expanding in all directions.expanding in all directions.

The Big Bang TheoryThe Big Bang TheoryCosmic Background Radiation: Cosmic Background Radiation:

radiation uniformly detected from every radiation uniformly detected from every direction in space, considered a direction in space, considered a remnant of the big bang.remnant of the big bang.

Dark Energy / Dark MatterDark Energy / Dark Matter

Dark Matter:Dark Matter: matter that does not give off matter that does not give off light but that has gravity that we can light but that has gravity that we can detect. (23% of the universe)detect. (23% of the universe)

Dark Energy: Dark Energy: acts as a force that acts as a force that opposes gravity. opposes gravity.

And the rest…And the rest…