Stars and GalaxiesStars and Galaxies

Created by the Lunar and Planetary InstituteFor Educational Use Only

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

Welcome!Welcome!

Please complete the pre-assessmentPlease complete the pre-assessmentIt’s for us—it’s not about youIt’s for us—it’s not about youPlease let us know how much YOU know, Please let us know how much YOU know,

not how much your friends sitting next to not how much your friends sitting next to you knowyou know

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

Our Place in the UniverseOur Place in the UniverseThe Electromagnetic SpectrumThe Electromagnetic SpectrumClassifying StarsClassifying StarsClassifying GalaxiesClassifying GalaxiesHistory of the UniverseHistory of the Universe

First up…First up…

Our Place in the UniverseOur Place in the UniverseWhat is our Universe made of?What is our Universe made of?How big are things? How far away?How big are things? How far away?How do we know?How do we know?

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

What was in your drawing?What was in your drawing?

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

Activity!!Activity!!

Use the Venn diagrams to place the stickersUse the Venn diagrams to place the stickers—where does everything go?—where does everything go?

After you’re finished, let’s discuss…After you’re finished, let’s discuss…

Examining the ComponentsExamining the Components

Stars Stars Gas and dust (Nebulae)Gas and dust (Nebulae)Star clustersStar clustersGalaxiesGalaxies

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 groupsAloneAlone

More laterMore later

What is a “star cluster”?What is a “star cluster”?

stars formed together at same time

stars may be gravitationally bound together

two types: open (galactic) and globular

Image at http://hubblesite.org/newscenter/archive/releases/star%20cluster/globular/2007/18/image/a/format/web/results/50/

Open ClustersOpen Clusters

dozens to thousands of starsyoung stars! only a few

million years oldmay still be surrounded by

nebula from which they formedlocated in the spiral arms of a

galaxyexample: Pleiades

Image at http://hubblesite.org/newscenter/archive/releases/star%20cluster/open/2004/20/image/a/results/50/

More open star clustersMore open star clusters

Image from http://hubblesite.org/newscenter/archive/releases/star%20cluster/open/2006/17/image/a/results/50/

Globular ClustersGlobular Clusters

millions to hundreds of millions of stars

old! 6 to 13 billion years mostly red giants and dwarfs stars are clumped closely together,

especially near the center of the cluster (densely)

surround our disk as a halo

Image at http://hubblesite.org/newscenter/archive/releases/star%20cluster/globular/1999/26/image/a/results/50/

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

A cloud in spaceA cloud in spaceMade of gas and dust Made of gas and dust

Can have stars inside

Most of the ones we see are inside our Milky Way Most of the ones we see are inside our Milky Way GalaxyGalaxy

Different typesDifferent types

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

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/

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/

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

A large group of stars outside of our own Milky WayA large group of stars outside of our own Milky WayMade of billions to trillions of starsMade of billions to trillions of stars

Also may have gas and dust Also may have gas and dust

Spiral, or elliptical, or irregular shapedSpiral, or elliptical, or irregular shapedImage at http://hubblesite.org/newscenter/archive/releases/galaxy/spiral/2007/41/results/50/

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

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/

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

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

The Milky WayThe Milky Way

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

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?

Measuring DistancesMeasuring Distances

Parallax (let’s model it)Parallax (let’s model it) As Earth orbits the Sun, we see nearby stars move relative to more distant stars

How many degrees did the plate move, relative to the background?

Can you calculate the distance to the plate?

Sine of the parallax (angle) x Earth’s distance to the Sun = Distance to the star

The angles involved for strellar observations are very small and difficult to measure. Proxima Centauri, has a parallax of 0.77 arcsec. This angle is approximately the angle subtended by an object about 2 centimeters in diameter located about 5.3 kilometers away.

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; how far velocity of about 300,000 kilometers (km) each second; how far would it move in a year?would it move in a year?

About 10 trillion km (or about 6 trillion miles).About 10 trillion km (or about 6 trillion miles).

Why do we use light years?Why do we use light years? Show me how far 5 centimeters is.Show me how far 5 centimeters is. Now show me 50 centimeters.Now show me 50 centimeters. Now tell me (without thinking about it, or calculating it in meters) how far Now tell me (without thinking about it, or calculating it in meters) how far

500 centemeters is. 2000? 20,000?500 centemeters is. 2000? 20,000? We need numbers that make sense to us in relationship to objects; we We need numbers that make sense to us in relationship to objects; we

scale up and use meters and kilometers for large numbers.scale up and use meters and kilometers for large numbers.

Time for a Break! Next UpTime for a Break! Next Up

Our Place in the UniverseOur Place in the UniverseThe Electromagnetic SpectrumThe Electromagnetic SpectrumClassifying StarsClassifying StarsClassifying GalaxiesClassifying GalaxiesHistory of the UniverseHistory of the Universe

Let’s check your knowledgeLet’s check your knowledge

Please draw an electromagnetic spectrum Please draw an electromagnetic spectrum on a sheet of paper, and label the parts.on a sheet of paper, and label the parts.

You can work in groups.You can work in groups.

RadiationRadiation

There are lots of types of light (radiation), There are lots of types of light (radiation), including visible and invisibleincluding visible and invisible

Electromagnetic spectrum

http://coolcosmos.ipac.caltech.edu/cosmic_classroom/ir_tutorial/what_is_ir.html

.

Let’s Observe A SpectrumLet’s Observe A Spectrum

What will the spectrum look like with a red What will the spectrum look like with a red filter in front of your eyes? A blue filter?filter in front of your eyes? A blue filter?

Hypothesize and test your hypothesis.Hypothesize and test your hypothesis.

Now let’s examine the invisible parts—Now let’s examine the invisible parts—using our cell phones and a solar cell.using our cell phones and a solar cell.

There are different types of spectraThere are different types of spectra

ContinuousContinuousEmission or Bright Line (from ionized gas, like Emission or Bright Line (from ionized gas, like

a nebula or a neon sign)a nebula or a neon sign)Absorption or dark line (from stars)Absorption or dark line (from stars)

Illustration at http://imagine.gsfc.nasa.gov/docs/science/how_l1/spectra.html

RadiationRadiation

All stars emit radiationAll stars emit radiation Radio, infrared, visible, ultraviolet, x-ray and even some gamma Radio, infrared, visible, ultraviolet, x-ray and even some gamma

raysrays Most sunlight is yellow-green visible light or close to itMost sunlight is yellow-green visible light or close to it

The Sun at X-ray wavelengths

Image at http://imagine.gsfc.nasa.gov/docs/science/know_l1/sun.html

Image and info at http://imagine.gsfc.nasa.gov/docs/teachers/gammaraybursts/imagine/page18.html

.

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

Stellar EvolutionStellar Evolution

Time to Create a Stellar GraphTime to Create a Stellar Graph

Everyone will receive several “stars”Everyone will receive several “stars”Place them on the large paper, according to Place them on the large paper, according to

their color and their brightnesstheir color and their brightnessThis is a version of the Hertzsprung-Russell This is a version of the Hertzsprung-Russell

diagram.diagram.

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

Young stars form in nebulae

from Small Magellanic Cloud

Young stars form in nebulae

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/

Interstellar “eggs”Interstellar “eggs”

Movie at http://www.stsci.edu/EPA/PR/95/44/M16.mpg

Our Sun is a Regular/ Small StarOur Sun is a Regular/ Small Star

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

On the “Main Sequence”On the “Main Sequence”

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/

Our Sun’s Habitable ZoneOur Sun’s Habitable Zone

Billions of years ago, things may have Billions of years ago, things may have been differentbeen different The Sun was cooler (by up to 30%!)The Sun was cooler (by up to 30%!) Earth’s atmosphere was different (thicker, Earth’s atmosphere was different (thicker,

carbon dioxide)carbon dioxide)

Conditions will be different in the Conditions will be different in the futurefuture By many accounts, increases in the Sun’s By many accounts, increases in the Sun’s

temperature will make Earth uninhabitable in temperature will make Earth uninhabitable in 1 billion years or less1 billion years or less

These changes will also affect other planets… These changes will also affect other planets… Mars?Mars?

Animation at http://www.nasa.gov/97994main_BHabitableZone.MPG

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

Image at http://hubblesite.org/newscenter/archive/releases/nebula/planetary/2000/28/image/a/format/web_print/results/50/