Stars, The Universe

and Galaxies

Stars, The Universe

and Galaxies

Image at http://hubblesite.org/newscenter/archive/releases/galaxy/spiral/2009/07/image/g/results/50/

What are we going to cover?What are we going to cover?

Classifying StarsClassifying StarsHistory of the UniverseHistory of the UniverseClassifying GalaxiesClassifying Galaxies

Different types of stars

Different types of stars

Image from http://hubblesite.org/newscenter/archive/releases/star%20cluster/globular/2003/21/image/a/results/50/

Types of StarsTypes of Stars

BigBigSmallSmallRedRedBlueBlueYellowYellowIn groupsIn groups

What is a “nebula”?What is a “nebula”?

A cloud in space made of gas and dust, where A cloud in space made of gas and dust, where stars are born stars are born

Most of the ones we see are inside our Milky Most of the ones we see are inside our Milky Way GalaxyWay Galaxy

Orion image at http://hubblesite.org/newscenter/archive/releases/2006/01/image/a/results/50/

Life Cycle of a starLife Cycle of a star

Low mass star

Main Sequence

Red Giant

Planetary Nebula

White dwarf

Stellar Nebula- ProtostarStellar Nebula- Protostar

High-mass starHigh-mass star

main sequencemain sequencered supergiantred supergiantsupernovasupernova

Neutron star or black holeNeutron star or black hole (Depending on mass)(Depending on mass)

Magnitude of starsMagnitude of stars

Absolute MagnitudeAbsolute Magnitude- a measure of the - a measure of the amount of light a star gives off (luminosity-amount of light a star gives off (luminosity-how bright)how bright)

Apparent MagnitudeApparent Magnitude- amount of light - amount of light received on Earth (the way it appears to us)received on Earth (the way it appears to us)

Large, massive, bright nebulaeLarge, massive, bright nebulae

Emission NebulaEmission Nebula•The hot gas is emitting lightThe hot gas is emitting light

Orion image at http://hubblesite.org/newscenter/archive/releases/2006/01/image/a/results/50/

Colder, darker nebulaeColder, darker nebulae

Dark dust blocking the hot Dark dust blocking the hot gas behind itgas behind it

NOAO/AURA/NSF Image from http://hubblesite.org/newscenter/archive/releases/nebula/dark/2001/12/image/c/results/50/

Young stars and some planets form in nebular cloud

from Small Magellanic Cloud

Young stars and some planets form in nebular cloud

from Small Magellanic Cloud

Image at http://hubblesite.org/newscenter/archive/releases/2007/04/image/a/results/50/

Star-forming region in the Large Magellanic Cloud: http://hubblesite.org/newscenter/archive/releases/2008/31/image/a/results/50/

Orion image at http://hubblesite.org/newscenter/archive/releases/2006/01/image/a/results/50/

Neutron Star or PulsarNeutron Star or Pulsar

Image at http://hubblesite.org/newscenter/archive/releases/nebula/supernova-remnant/2002/24/results/50/

Supernova—Massive Star ExplodesSupernova—Massive Star Explodes

Images at

http://hubblesite.org/newscenter/archive/releases/star/supernova/2004/09/results/50/ http://hubblesite.org/newscenter/archive/releases/nebula/supernova-remnant/2005/37/results/50/

http://chandra.harvard.edu/photo/2009/casa/

Leftovers from an ExplosionLeftovers from an Explosion

Supernova remnantSupernova remnant (smaller, less gas) (smaller, less gas)

Image at http://hubblesite.org/newscenter/archive/releases/nebula/supernova-remnant/2005/37/results/50/

H-R DiagramH-R Diagram

Indicates differences and relationships Indicates differences and relationships between starsbetween stars

Horizontal axis (X) = surface tempHorizontal axis (X) = surface tempVertical axis (Y) = Luminosity-absolute Vertical axis (Y) = Luminosity-absolute

magnitude (brightness)magnitude (brightness)Sun rests in the middle-we use for Sun rests in the middle-we use for

comparisoncomparison

Using a Star’s SpectrumUsing a Star’s Spectrum

We can use a star’s spectrum to classify it.We can use a star’s spectrum to classify it.

NOAO/AURA/NSF image at http://antwrp.gsfc.nasa.gov/apod/ap010530.html

Hertzsprung-Russell DiagramHertzsprung-Russell Diagram

Images from http://www.nasa.gov/centers/goddard/news/topstory/2007/spectrum_plants.html and http://sunearthday.gsfc.nasa.gov/2009/TTT/65_surfacetemp.php

Black HoleBlack Hole

A black hole is a dense well thought to have A black hole is a dense well thought to have zero volume but infinite densityzero volume but infinite density

Its gravity is so strong that not even light is Its gravity is so strong that not even light is fast enough to escape itfast enough to escape it

Scientists hypothesize that black holes are Scientists hypothesize that black holes are remnants of supernova explosions. (When a remnants of supernova explosions. (When a star uses up all its fuel and explodes, the star uses up all its fuel and explodes, the gases and dust that remain collapse to form gases and dust that remain collapse to form the black hole.)the black hole.)

Our Sun Our Sun

Image at http://www.gsfc.nasa.gov/topstory/20011210insidesun.html

•Regular/medium Regular/medium sized starsized star•Average temp Average temp and brightnessand brightness•On an outer arm On an outer arm and far away and far away from the center of from the center of the Milky Waythe Milky Way

Our SunOur Sun

Main Sequence stage of lifeNuclear Fusion reactions (2 atoms jammed together-

energy emitted as light and heat)- converts 600,000,000 tons of hydrogen into helium every second

93 million miles or 150 million km from Earth (closer than any other star)

A planet’s characteristics are often determined by distance from the Sun (ex- rocky, gaseous, temperature)

In a few Billion years… Red GiantIn a few Billion years… Red Giant

Image at http://hubblesite.org/newscenter/archive/releases/1997/26/image/a/

By 5 billion years… White DwarfBy 5 billion years… White Dwarf

Image at http://hubblesite.org/newscenter/archive/releases/nebula/planetary/1998/39/results/50/

Small, but very hotSmall, but very hot

Building a UniverseBuilding a Universe

Instantaneous filling of Instantaneous filling of space with all matterspace with all matter

What is our Universe made of?What is our Universe made of?

Stars and planetsStars and planets Gas and dustGas and dust Organized into star clustersOrganized into star clusters Organized into nebulaeOrganized into nebulae Organized into galaxiesOrganized into galaxies Other things:Other things:

Black holesBlack holes Dark matterDark matter Dark energyDark energy

Image from http://galileo.rice.edu/lib/student_work/astronomy95/orionpleiades.html

When Did the Universe Form?When Did the Universe Form?

~13.7 billion years ago ~13.7 billion years ago

How do we know? How do we know? Spreading (Red Shift)Spreading (Red Shift) - -

know distances, rates of know distances, rates of

retreat, relative positionsretreat, relative positions Pervasive Pervasive background background

radiationradiation of 2.7°C above of 2.7°C above absolute zeroabsolute zero - afterglow - afterglow of the Big Bangof the Big Bang

http://timeline.aps.org/APS/resources/85_06a.jpg

Cosmic background radiation temperature on celestial sphere

History of the UniverseHistory of the Universe

•10-43 seconds - gravity separates from other forces

•10-35 to 10-32 seconds - fundamental particles - quarks and electrons

•10-6 seconds - quarks combine into protons and neutrons

•1 second - electromagnetic and weak nuclear forces separate

•3 minutes - protons and neutrons combine into atomic nuclei

•105 years - electrons join nuclei to make atoms; light is emitted

•105-109 years - matter collapses into clouds, making galaxies and stars

Orion Nebula - http://stardate.utexas.edu/resources/ssguide/planet_form.html

History of the UniverseHistory of the Universe

Image from Image from http://dsc.discovery.com/space/top-10/strange-universe/space-10-weirdest-things-universe-10.htmlhttp://dsc.discovery.com/space/top-10/strange-universe/space-10-weirdest-things-universe-10.html

Later HistoryLater History

Image at http://www.galex.caltech.edu/media/glx2004-01r_img02.html

Big Bang TheoryBig Bang Theory

Image at Image at http://map.gsfc.nasa.gov/universe/bb_theory.htmlhttp://map.gsfc.nasa.gov/universe/bb_theory.html

In 1915, Albert Einstein concluded that the universe could not be static based on his recently-discovered theory of relativity and added a "cosmological constant" to the dded a "cosmological constant" to the theory of relativity because astronomers theory of relativity because astronomers assured him that the universe was staticassured him that the universe was static

Aleksandr Friedmann and Abbe George Aleksandr Friedmann and Abbe George LeMaitre are credited with developing the LeMaitre are credited with developing the basics of the Big Bang model between 1922 basics of the Big Bang model between 1922 and 1927; their calculations suggested that and 1927; their calculations suggested that universe is expandinguniverse is expanding, not static., not static.

Years later, Einstein called his cosmological Years later, Einstein called his cosmological constant the constant the biggest mistake of his careerbiggest mistake of his career

Expanding UniverseExpanding Universe

In 1929, Edwin Hubble showed that most In 1929, Edwin Hubble showed that most galaxies are red-shifted (moving away galaxies are red-shifted (moving away from us), and that a galaxy’s velocity is from us), and that a galaxy’s velocity is proportional to its distance (galaxies that proportional to its distance (galaxies that are twice as far from us move twice as are twice as far from us move twice as fast)fast)

Image from http://imagine.gsfc.nasa.gov/docs/science/mysteries_l1/origin_destiny.html

Hubble’s EvidenceHubble’s Evidence

Doppler shifting - wavelength emitted by something moving away Doppler shifting - wavelength emitted by something moving away from us is shifted to a lower frequencyfrom us is shifted to a lower frequency

Sound of a fire truck siren - pitch of the siren is higher as the fire Sound of a fire truck siren - pitch of the siren is higher as the fire truck moves towards you, and lower as it moves away from you truck moves towards you, and lower as it moves away from you

Visible wavelengths emitted by objects moving away from us are Visible wavelengths emitted by objects moving away from us are shifted towards the red part of the visible spectrumshifted towards the red part of the visible spectrum

The faster they move away from us, the more they are redshifted. The faster they move away from us, the more they are redshifted. Thus, redshift is a reasonable way to measure the speed of an Thus, redshift is a reasonable way to measure the speed of an object.object.

When we observe the redshift of galaxies, almost every galaxy When we observe the redshift of galaxies, almost every galaxy appears to be moving away from us – the Universe is expanding. appears to be moving away from us – the Universe is expanding.

Origin of the Universe

Data collected (from Hubble Data collected (from Hubble Telescope) is used as evidence to Telescope) is used as evidence to help develop scientific theorieshelp develop scientific theories

Big BangBig Bang

Dominant scientific theory about the Dominant scientific theory about the origin of the universeorigin of the universe

Occurred ~13.7 billion years agoOccurred ~13.7 billion years ago

What is the Big Bang?What is the Big Bang?

Infinitely dense point Infinitely dense point not governed by our not governed by our physical laws or timephysical laws or time

All matter and energy All matter and energy contained in one pointcontained in one point

Image from Image from http://www.newscientist.com/articleimages/dn11799/0-did-antimatter-factoryhttp://www.newscientist.com/articleimages/dn11799/0-did-antimatter-factory-spark-brightest-supernova.html-spark-brightest-supernova.html

Predictions for the Big Bang ModelPredictions for the Big Bang Model

The expansion of the Universe Edwin Hubble's 1929 observation that galaxies were generally Edwin Hubble's 1929 observation that galaxies were generally

receding from us provided the first clue that the Big Bang theory receding from us provided the first clue that the Big Bang theory might be right. might be right.

The abundance of the light elements H, He, Li The Big Bang theory predicts that these light elements should have The Big Bang theory predicts that these light elements should have

been fused from protons and neutrons in the first few minutes after been fused from protons and neutrons in the first few minutes after the Big Bang. the Big Bang.

The cosmic microwave background (CMB) radiation The early universe should have been very hot. The cosmic The early universe should have been very hot. The cosmic

microwave background radiation is the remnant heat leftover from microwave background radiation is the remnant heat leftover from the Big Bang. the Big Bang.

Evidence for Big BangEvidence for Big Bang

Red shiftRed shift - as light from distant galaxies approach earth there is an - as light from distant galaxies approach earth there is an increase of space between earth and the galaxy, which leads to increase of space between earth and the galaxy, which leads to wavelengths being stretchedwavelengths being stretched

In 1964, Arno Penzias and Robert Wilson, discovered a noise of In 1964, Arno Penzias and Robert Wilson, discovered a noise of extraterrestrial origin that came from all directions at once - extraterrestrial origin that came from all directions at once - radiationradiation left left over from the Big Bangover from the Big Bang

In June 1995, scientists detected In June 1995, scientists detected heliumhelium in the far reaches of the universe in the far reaches of the universe - consistent with an important aspect of the Big Bang theory that a - consistent with an important aspect of the Big Bang theory that a mixture of hydrogen (75%) and helium (25%) was created at the mixture of hydrogen (75%) and helium (25%) was created at the beginning of the universebeginning of the universe

Measuring DistancesMeasuring Distances

What is a Light Year?What is a Light Year?A light year is the distance light travels in a year. Light moves at a A light year is the distance light travels in a year. Light moves at a

velocity of about 300,000 kilometers (km) each second; velocity of about 300,000 kilometers (km) each second; ~ 6 trillion miles or ~ 10 trillion km~ 6 trillion miles or ~ 10 trillion km

Astronomical Unit:150 million KilometersAstronomical Unit:150 million Kilometers

Why do we use light years?Why do we use light years?We need numbers that make sense to us in relationship to objects; We need numbers that make sense to us in relationship to objects;

we scale up and use meters and kilometers for large numbers.we scale up and use meters and kilometers for large numbers.Distances between stars and galaxiesDistances between stars and galaxiesDifferent wavelengths of Electromagnetic spectrum are used to Different wavelengths of Electromagnetic spectrum are used to

gain information about distances and properties of components in gain information about distances and properties of components in the universethe universe

What is a “galaxy”?What is a “galaxy”?

Image at http://hubblesite.org/newscenter/archive/releases/galaxy/spiral/2007/41/results/50/

GalaxiesGalaxies

System of stars , dust, and gases that are held System of stars , dust, and gases that are held together by gravity and categorized by shapetogether by gravity and categorized by shape

come in different shapes and classificationsSpiralsEllipticalsIrregulars

are fairly close together, relative to their sizes

Elliptical GalaxiesElliptical Galaxies

Images at http://hubblesite.org/newscenter/archive/releases/galaxy/elliptical/2007/08/image/a/format/large_web/results/50/ and http://hubblesite.org/newscenter/archive/releases/galaxy/elliptical/1995/07/results/50/

Elliptical galaxiesElliptical galaxies

range from spherical to football shapedrange from very small to gianthave very little gas or dustmostly old stars

Spiral galaxy--AndromedaSpiral galaxy--Andromeda

NOAO/AURA/NSF Images at http://www.noao.edu/image_gallery/html/im0606.html and http://www.noao.edu/image_gallery/html/im0685.html

Spiral GalaxiesSpiral Galaxies

have flat disk, spiral arms, central bulge, and a surrounding halo

some have a “barred” bulgeare fairly large (no dwarf spirals)have lots of gas and dust and younger stars in their

arms, but older stars and little gas or dust in their halos and central bulges

EX: Our Galaxy… The Milky Way

Spiral Galaxy on Edge

Spiral Galaxy on Edge

Image at http://hubblesite.org/newscenter/archive/releases/galaxy/spiral/2006/24/image/a/results/50/

Our Galaxy: the Milky WayOur Galaxy: the Milky Way

has about 200 billion stars, and lots of gas and dust

is a barred-spiral (we think)about 100,000 light-years wideour Sun is halfway to the edge, revolving at

half a million miles per hour around the center of the Galaxy

takes our Solar System about 200 million years to revolve once around our galaxy

Mapping the Milky WayMapping the Milky Way

We can see stars We can see stars star clustersstar clusters nebulaenebulae GalaxiesGalaxies

Let’s try to Map our GalaxyLet’s try to Map our Galaxy

How do we know what our Galaxy How do we know what our Galaxy looks like?looks like?

The Milky WayThe Milky Way

Image at http://news.nationalgeographic.com/news/bigphotos/1945371.html

Irregular GalaxiesIrregular Galaxies

NASA and NOAO/AURA/NSF Images at http://hubblesite.org/newscenter/archive/releases/galaxy/irregular/2005/09/results/50/ , http://www.noao.edu/image_gallery/html/im0560.html , and http://www.noao.edu/image_gallery/html/im0993.html

Irregular GalaxiesIrregular Galaxies

No distinct shape or sizeusually have lots of gas and dust and young

starsmay have a distorted shape from interaction

with another galaxy

Active galaxyActive galaxy

Image at http://hubblesite.org/newscenter/archive/releases/galaxy/spiral/2000/37/results/50/

at the center of a large galaxyat the center of a large galaxy

Image at http://hubblesite.org/newscenter/archive/releases/exotic/black-hole/1998/22/results/20/ and

http://hubblesite.org/newscenter/archive/releases/exotic/black%20hole/2000/21/image/a/format/web_print/results/20/