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Stars

Stars. Constellations. A group of stars that appears to form a pattern in the sky. AQUARIUS. Virgo. Constellations -. total of 88 different constellations can be seen in the N and S hemispheres As you move north you can see more stars. Andromeda. Aries. Constellations-.

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Stars

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  1. Stars

  2. Constellations • A group of stars that appears to form a pattern in the sky AQUARIUS Virgo

  3. Constellations - • total of 88 different constellations can be seen in the N and S hemispheres • As you move north you can see more stars. Andromeda Aries

  4. Constellations- • Ursa Major - (Big Bear) is the most famous constellation

  5. Constellations- • The Big Dipper is part of Ursa Major

  6. Constellations- • Two stars of Ursa Major are used to find the North star- Polaris-(pole star) ?1&2 Polaris

  7. Constellations- • Polaris is part of Ursa Minor (the little dipper) Ursa Minor

  8. Constellations- • As the earth rotates on its axis the constellations move. • They rotate around Polaris counter clockwise. • The earth’s axis points toward the N. Star Pg. 617 (fig. 28.2)

  9. Orion in Winter Constellations- • Some constellations can only be seen during specific seasons • This is due to earth’s rotation around sun and tilt of the earth Lyra in summer ?3,4&5

  10. Circumpolar Rotation around Polaris

  11. What happens as you travel North? • The number of circumpolar stars visible, increases as the observer moves North

  12. Can you tell what constellations these are?

  13. ?6 Ursa Major

  14. ?7 Lyra

  15. ?8 Orion

  16. Aquarius

  17. Gemini

  18. Stars- How far to a star? • Closest Star = Sun 93,000,000 miles = 1 astronomical unit • Next closest star • Proxima Centauri • 25 trillion miles • 2.5 x 10 13 • 4.2 light years

  19. Light year- • Distance that light travels in one year • 5,900,000,000,000 miles • Polaris- 680 LY • Betelgeuse (red supergiant ) is 490 LY ?9

  20. Properties of Stars • Our Sun- • Diameter- • 855600 miles • 110x earth • Density • 1.4 x density H20 • Mass • 300,000x earth

  21. How does our sun compare? • Diameter- • average • Density- • mid to high • Mass- • Other stars range from 1/100th to 50x our sun

  22. How do we size up?

  23. Wow! Jupiter is BIG

  24. Our sun is REALLY BIG!

  25. Guess Not!

  26. We are REALLY SMALL! I feel so insignificant!

  27. Color? Depends on surface temperature cool Hot- ~30,000 ° C Medium- our sun (5500°C)

  28. Green stars look white to us! Classification of stars

  29. ?10 & 11 Spectroscopy! Composition of Stars- • How can we tell? • Our sun- • Hydrogen (70%) • Helium (28%) • No 2 stars have the same spectra (like a fingerprint) You know this!

  30. -Brightness- • Apparent Magnitude- • how bright a star appears to earth observer. • Depends on • Distance from us • what is between us • true brightness

  31. Brightness- • Luminosity- • True brightness • Depends on…(2 things) • Size -if same size, blue is more luminous • Temp.- if same temp., bigger is more luminous

  32. Absolute Magnitude- Rigel- foot of Orion 40,000 suns “Blue Super Giant” • How stars would appear if they were all the same distance from earth. • All stars place 32.6 LY from the sun • Our sun abs. Mag = 4.8 • Negative is brighter ?12

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