Chapter 26.2

Evolution of Stars

26.2

Journal Entry

Why do we study space? What types of information can we find in space? What is the most interesting thing that you have heard about space?

Discuss as a class…

Carousel Activity

Write a response to each question on the

poster boards around the room.

(Make sure you go to each poster board)

Carousel Activity

STOP HERE

1. Discuss answers written in response to questions. 2. Address misconceptions 3. Confirm concepts before proceeding with

presentation.

Astronomers’ Technology*used to study objects in space

1. Optical Telescopes – collect and magnify visible light

A. Reflecting OpticalB. Refracting Optical

2. Radio Telescopes- Collects and amplifies radio waves

3. Spectroscope - Separates light waves into electromagnetic spectra

1.Feather, Ralph M., Charles W. McLaughlin, Marilyn Thompson, and Dinah Zike. Florida Physical Science with Earth Science. New York: Glencoe/McGraw Hill, 2006.

Refracting Optical Telescope

• Uses a convex lens– Curved outward like the surface

of a ball• When the lens curves outward

on both sides, it is a double convex lens.

• Cannot be too large because the objective lens is only supported at its edges

– Light passes through the objective lens.

– The eyepiece then magnifies the image.

• which also can be a double convex lens


Reflecting Optical Telescopes

• Sir Isaac Newton invented in 1680• Uses a mirror as an objective to reflect light to the focus. • Light passes through the open end of a reflecting telescope

and strikes a concave mirror at the base of the telescope. – smaller mirror is used to reflect light into the eyepiece where it is

magnified for viewing. – OR-a person sits inside the telescope and looks through the

eyepiece at the focus.


Reflecting Optical Telescopes


2."Cool Cosmos." Welcome to Cool Cosmos! 19 Feb. 2009 <http://coolcosmos.ipac.caltech.edu/cosmic_classroom/multiwavelength_astronomy/multiwavelength_astronomy/observing.html>.

9

Radio Telescope

• Because radio waves have long wavelengths, a radio telescope must be built with a very large objective1

• Radio waves also bring us information about supernovae, quasars, pulsars, regions of gas between the stars, and interstellar molecules2


Game: Can you identify this?

• Hints:– Viewed the massive galaxy cluster Abell 2218

• 2,000,000,000 light years away (Remember: light years measure distance, not time!)

– Famous Space Telescope• Put in space so that Earth’s atmosphere does not interfere

with lenses’ ability to magnify objects

Game: Can you identify this?

HUBBLE SPACE TELESCOPE

Official Hubble Space Telescope Website

What types of space objects does Hubble find?

Spectroscope

• Technology used to separate light waves into electromagnetic spectra– Spectra: individual wavelengths of light

• ROYGBIV

– Color can tell a lot about the star’s composition• Brightest color in spectrum tells temperature

– Blue is hottest; red is coolest

• Chemical Composition

• Speed and Direction compared to Earth

– Remember: What is speed with direction?

» Velocity


Spectroscopy Video

1. Put stars in ascending temperature order

2. How can you tell how fast a star is rotating

3. Name 3 things we can learn about stars from using a spectroscope.

Spectroscopy Video

1. Put stars in ascending temperature order– Red, White, Yellow, Blue

2. How can you tell how fast a star is rotating

– Observe absorption lines

3. Name 3 things we can learn about stars from using a spectroscope.

– Various answers

Life Cycle of a Star

Watch a star grow.Sea and Sky - Explore the Oceans Below and the Skies Above. 19 Feb. 2009 <http://www.seasky.org/celestial-objects/assets/images/starlife.jpg>.

Star Formation

• Read p.823 “How do stars form?”In your own words, write how stars form.____________________________________

__________________________________________________________________________________________________________________________________________________________________________

Star Formation

• Gas, Ice and Dust Condense into a Nebula• Gravitational Force within the nebula increases

and pulls the particles close together• Because the cloud is unstable, it breaks into

smaller, more stable cloud fragments• Gravitational force again causes contraction• Close proximity of particles increases heat• At 1,000,000K = protostar• At 10,000,000K fusion begins and Star is born


Star Nebula

Protostar

Relative Ages of Stars

"Stars - Main Sequence." ASPIRE - Home. 19 Feb. 2009 <http://aspire.cosmic-ray.org/labs/star_life/starlife_sequence.html>.

How we measure stars:H-R Diagrams

• Compares Absolute Magnitude and Temperature• 90% of all stars are in main sequence (diagonal)• Higher temperature stars radiate more energy and

have higher absolute magnitudes1.Feather, Ralph M., Charles W. McLaughlin, Marilyn Thompson, and Dinah Zike. Florida Physical Science with Earth Science. New York: Glencoe/McGraw Hill, 2006.

STOP HERE

Distribute HR diagrams with questions

Interactive HR Diagram

Relative Size of the Sun


The Sun

Structure:• Layers:

– Core – fusion occurs here• Energy produced takes

millions of years to reach photosphere

– Radiation Layer• Gasses are ionized• No electrons remain on

atoms to capture photons• Fusion energy easily

transfers through this layer


The Sun

Structure:• Layers continued:

– Convection Layer• Temperature is lower,

photons are absorbed• Energy from photons is

carried to surface by convection

• Convection cells = areas where hot gasses rise and cooler gasses sink


The Sun

Structure:• Layers continued:

– Photosphere• surface of sun that

gives light

– Atmosphere• Chromosphere

• Corona


Photosphere

• Located at the top of the convective zone

• Granulation causes mottled appearance– Results from rising hot

material and sinking cooler material within convection cells

– Granules are approximately 1000 km across


Sunspots

• Cooler areas in photosphere – appear darker– Intense magnetic fields

produced

• Prove that the Sun does not rotate as a solid body – Scientists can see sunspots at

the equator rotate 6 days faster than those at 60 degrees north or south latitudes

• 25 days compared to 31 days

• Not permanent• Solar activity cycle is 11 year


Prominences and Flares

• Prominences– Arching columns of gas that erupt– Convection causes magnetized

gases to flow upward toward the photosphere

– If the magnetic field is strong enough near a pair of sunspots, it will cause a prominence to loop from one sunspot to another

• Solar Flares– 100 million K– So energy rich that the Sun’s

magnetic field cannot hold it– Shoots into space at 600-1000km/s

Solar Flare Simulation


10+5 Using Pages 824-825

Write 5 quiz questions using the following format…Then answer the questions

1. What causes __________?

2. Why did ___ do ____?

3. Explain _____________.

4. What is _________?

5. How does _________?

Chapter 26.2

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Transcript of Chapter 26.2