Download - Stars
![Page 1: Stars](https://reader033.vdocument.in/reader033/viewer/2022051620/5681377b550346895d9f14e8/html5/thumbnails/1.jpg)
Stars
The Brightness of Stars-Star: A luminous sphere of gas with enormous
mass, that produces energy by fusion.-Fusion: The joining of separate nuclei. Common in
nature, but not on Earth.
![Page 2: Stars](https://reader033.vdocument.in/reader033/viewer/2022051620/5681377b550346895d9f14e8/html5/thumbnails/2.jpg)
Actual vs. Apparent Brightness• Variables which
affect a star’s brightness:
1. Star size2. Distance from Earth3. Star temperature
• Apparent Brightness: The amount of light received on Earth from a star.• Actual Brightness:
How large and hot a star is in relation to other stars.
![Page 3: Stars](https://reader033.vdocument.in/reader033/viewer/2022051620/5681377b550346895d9f14e8/html5/thumbnails/3.jpg)
Star Brightness• Example: Sirius has a
greater apparent brightness then Rigel, even though Rigel is a much hotter and brighter star.• Why?
![Page 4: Stars](https://reader033.vdocument.in/reader033/viewer/2022051620/5681377b550346895d9f14e8/html5/thumbnails/4.jpg)
Lifecycle of Starsvideo: http://www.nationalstemcentre.org.uk/elibrary/resource/5415/the-life-cycle-of-stars
http://www.youtube.com/watch?v=4s7vyDLgk3M
http://www.enchantedlearning.com/sgifs/Starlifecycle.GIF
![Page 5: Stars](https://reader033.vdocument.in/reader033/viewer/2022051620/5681377b550346895d9f14e8/html5/thumbnails/5.jpg)
Star Lifecycle explained
“As space expands there are many more gaps forming and they need to be filled by stars and energy. So stars need to have a dynamic life cycle. Moments of birth and death, right? ”
http://library.thinkquest.org/C0110277/stars/life_cycle1.htm
![Page 6: Stars](https://reader033.vdocument.in/reader033/viewer/2022051620/5681377b550346895d9f14e8/html5/thumbnails/6.jpg)
Where are stars born?• Nebula (stellar nursery):
Stars are born in nebulae-- Huge clouds of dust and gas • Dust and gas particles
exert a gravitational force on each other which keeps pulling them closer together.
• Orion Nebula
![Page 7: Stars](https://reader033.vdocument.in/reader033/viewer/2022051620/5681377b550346895d9f14e8/html5/thumbnails/7.jpg)
More Nebulas• As the particles pull
closer together the temperature increases.• At 10,000,000o C
fusion takes place and energy radiates outward through the condensing ball of gas.
• Another view of Orion
![Page 8: Stars](https://reader033.vdocument.in/reader033/viewer/2022051620/5681377b550346895d9f14e8/html5/thumbnails/8.jpg)
Stellar Evolution – A sun-like star
http://www.enchantedlearning.com/subjects/astronomy/stars/lifecycle/sunlike.shtml
http://t1.gstatic.com/images?q=tbn:ANd9GcT_XJP25-_6XInCs2WJ2x3ramBhnn-tqYRcDHvFfj96_z1LHKO8kw
![Page 9: Stars](https://reader033.vdocument.in/reader033/viewer/2022051620/5681377b550346895d9f14e8/html5/thumbnails/9.jpg)
Huge Stars…
http://www.enchantedlearning.com/subjects/astronomy/stars/lifecycle/huge.shtml
![Page 10: Stars](https://reader033.vdocument.in/reader033/viewer/2022051620/5681377b550346895d9f14e8/html5/thumbnails/10.jpg)
Giant Stars…
http://www.enchantedlearning.com/subjects/astronomy/stars/lifecycle/giant.shtml
![Page 11: Stars](https://reader033.vdocument.in/reader033/viewer/2022051620/5681377b550346895d9f14e8/html5/thumbnails/11.jpg)
Nothing (even light) can escape the gravity of a BLACK HOLEVideos:
http://www.space.com/15421-black-holes-facts-formation-discovery-sdcmp.html
http://dsc.discovery.com/tv-shows/other-shows/videos/stephen-hawkings-universe-black-hole-time.htm
http://dsc.discovery.com/tv-shows/other-shows/videos/how-the-universe-works-birth-of-a-black-hole.htm
![Page 12: Stars](https://reader033.vdocument.in/reader033/viewer/2022051620/5681377b550346895d9f14e8/html5/thumbnails/12.jpg)
Hertzsprung-Russell Diagramhttp://aspire.cosmic-ray.org/labs/star_life/hr_diagram.html
![Page 13: Stars](https://reader033.vdocument.in/reader033/viewer/2022051620/5681377b550346895d9f14e8/html5/thumbnails/13.jpg)
Determining a Star’s Temperature• A star’s temperature can be determined by its color.• All objects will glow a different color when heated differently• Colors hottest to coolest: Blue/white yellow orange
red.
![Page 14: Stars](https://reader033.vdocument.in/reader033/viewer/2022051620/5681377b550346895d9f14e8/html5/thumbnails/14.jpg)
Light-Years• Light-year: Distance light travels in one year. (Equal to about
9.5 trillion kilometers)• Approximate distances:
-Sun to edge of solar system = 5.5 light hours-Nearest star (Alpha Centauri) = 4.3 light years-Center to edge of Milky Way = 50,000 light years
![Page 15: Stars](https://reader033.vdocument.in/reader033/viewer/2022051620/5681377b550346895d9f14e8/html5/thumbnails/15.jpg)
The Sun and You
• Our sun is a main sequence star according to the H-R Diagram.• The actual
brightness is average for a star of its average size.
![Page 16: Stars](https://reader033.vdocument.in/reader033/viewer/2022051620/5681377b550346895d9f14e8/html5/thumbnails/16.jpg)
Layers of the Sun• Dense inner core
which is the site of hydrogen fusion.• Radiation zone:
Energy bounces back and forth before escaping.• Convections zone:
Cooler layer of gas that is constantly rising and sinking.
![Page 17: Stars](https://reader033.vdocument.in/reader033/viewer/2022051620/5681377b550346895d9f14e8/html5/thumbnails/17.jpg)
Anatomy of Sun
• Photosphere: Bright source of much of the light we see.• Chromosphere:
Active layer which is home to many significant displays.
![Page 18: Stars](https://reader033.vdocument.in/reader033/viewer/2022051620/5681377b550346895d9f14e8/html5/thumbnails/18.jpg)
Anatomy of Sun
• Corona: Outer layer which is a gradual boundary between sun and space.
![Page 19: Stars](https://reader033.vdocument.in/reader033/viewer/2022051620/5681377b550346895d9f14e8/html5/thumbnails/19.jpg)
Sunspots• Sunspots: Cool dark
areas on the sun’s surface.-First discovered by Galileo-Not permanent features—Will appear and disappear
![Page 20: Stars](https://reader033.vdocument.in/reader033/viewer/2022051620/5681377b550346895d9f14e8/html5/thumbnails/20.jpg)
Cycle of Solar Activity• Cycle of Solar
Activity: 11 year cycle which see number of sunspots change.• Sunspot Maximum:
Time of many large sunspots.• Sunspot Minimum:
Time of few sunspots.
![Page 21: Stars](https://reader033.vdocument.in/reader033/viewer/2022051620/5681377b550346895d9f14e8/html5/thumbnails/21.jpg)
Solar Flares• Solar Flares: Violent
eruptions near a sunspot which suddenly brighten and shoot outward at high speed.
![Page 22: Stars](https://reader033.vdocument.in/reader033/viewer/2022051620/5681377b550346895d9f14e8/html5/thumbnails/22.jpg)
Solar Flares• The interaction of solar flares with Earth’s magnetic field
causes the aurora borealis/ aurora australis (Northern/Southern Lights)
![Page 23: Stars](https://reader033.vdocument.in/reader033/viewer/2022051620/5681377b550346895d9f14e8/html5/thumbnails/23.jpg)
Earth’s Galaxy—and Others• Galaxy: A large group
of stars, gas, and dust held together by gravity.• Milky Way: Our
galaxy which contains about 200 billion stars and many nebulas
• Spiral Galaxies
![Page 24: Stars](https://reader033.vdocument.in/reader033/viewer/2022051620/5681377b550346895d9f14e8/html5/thumbnails/24.jpg)
Earth’s Galaxy—and Others• Galaxies are grouped
together in clusters.• The cluster the Milky
Way belongs to is called the Local Group.• Three types of
galaxies:
• Cluster of galaxies
![Page 25: Stars](https://reader033.vdocument.in/reader033/viewer/2022051620/5681377b550346895d9f14e8/html5/thumbnails/25.jpg)
Elliptical Galaxies• Elliptical Galaxies:
Most common type of galaxy; large three-dimensional football shaped galaxies.
-Contain mostly older and dimmer stars.
![Page 26: Stars](https://reader033.vdocument.in/reader033/viewer/2022051620/5681377b550346895d9f14e8/html5/thumbnails/26.jpg)
Spiral Galaxies• Spiral Galaxies:
Circular galaxies that have arms curve outward from a central hub.• Arms are made up
of stars and dust
• Two spiral galaxies!!
![Page 27: Stars](https://reader033.vdocument.in/reader033/viewer/2022051620/5681377b550346895d9f14e8/html5/thumbnails/27.jpg)
More Spiral Galaxies• Barred spiral
galaxies: Have two spiral arms extending out.
![Page 28: Stars](https://reader033.vdocument.in/reader033/viewer/2022051620/5681377b550346895d9f14e8/html5/thumbnails/28.jpg)
Irregular Galaxies• Irregular Galaxies:
Come in many different shapes and are smaller and less common than elliptical or spiral galaxies.
![Page 29: Stars](https://reader033.vdocument.in/reader033/viewer/2022051620/5681377b550346895d9f14e8/html5/thumbnails/29.jpg)
The Milky Way Galaxy• 100,000 light years in diameter• Our sun orbits the center of the galaxy once every 240 million
years• Probably a barred spiral galaxy• Contains over 200 billion stars