Stars and Galaxies

1. Stars and Galaxies

2. Unit: Stars & Galaxies Topic: Our Sun • Objectives: Day 1 of 4 • I will learn the definition of a star • I will learn the process of fusion in the sun’s core • I will be able to distinguish between the inner and outer layers of the sun

3. Quickwrite: Answer one of the questions below in 1-2 sentences: • What do you think fuels the sun???? A big tank of gas??? Nuclear energy???? • How long do you think it takes light to reach earth from the sun???? • How do you think energy from the sun reaches earth???

4. Radio Waves & Microwaves Infrared (heat) Visible Light Ultra Violet X-Rays Gamma Rays Ultra Violet (UV) radiation from the Sun has an even shorter wavelength. UV Radiation is absorbed by the earth’s ozone layer & can cause skin cancer Due to their short wavelength,X-Rays are even more hazardous to your health. This is why doctor’s put a lead vest over you when you get X-rays for an injury GammaRadiation has the shortest wavelengths of all radiation and is thereforeJust small amounts can be fatal. VisibleLight from the Sun has an even shorter wavelength. Light waves are the only type of radiation we can see. Infrared or heat waves have a shorter wavelength than radio waves. Heat Waves or radiation form the sun is what controls our weather Radio Waves are given off by the Sun. These are long wavelength waves and create the static you get on your radios and TV’s

5. What is a Star? • A sphere of gases that produces heat and light through the ____ of hydrogen • Our sun is average star Answer Bank stars Transfer Cool fusion photosphere 4

6. Inner layers • Core • Radiative Zone • Convection Zone

7. Core • The core lies in the heart of the sun and is 15,600,000 degrees Celsius • The nuclear process know as hydrogen fusion occurs in the core • During Hydrogen Fusion, 4 hydrogen combine to form 1 helium nucleus releasing tremendous amounts of energy • 4 H = 1 He + energy • Think Hydrogen Bomb!

8. In the Core, Pressures and Temperatures are high enough for Fusion to take place The core, where nuclear fusion takes place let’s zoom in and what happens H H He He He He H In the process, energy is released in the form of light &radiation H Fusion occurs when 4 hydrogen atoms (light element) combines to form 1 Helium atom (heavier element) Hydrogen, a lighter element is converted into a heavier element, helium

9. What is Fusion? Answer Bank stars Transfer Cool photosphere 4 • The combining of lighter elements to form heavier elements • In the Sun’s core, ___ hydrogen atoms (a light element [don’t write] ) combine to form 1 helium atom (a heavier element [don’t write] ) & energy is released H H H H H H H H He He He He He He He He He He He He He He He He H H H H H H H H

10. Radiative Zone • In the radiative zone, energy moves radiates outward from the core in the form of light & radiation • It takes light thousands of years to move from the core to the next layer • Temperature is 8,000,000 degrees Celsius

11. Convection Zone • Energy moves through this zone by convection • Hot gases rise toward the surface while cooler gases sink back down • It’s behaves like a giant pot of boiling water • Temp = 2,000,000 degrees Celsius

12. Outer Layers • Photosphere • Chromosphere • Corona (not visible)

13. Photosphere • Often called the surface of the sun • Where light is given off • Temperatures are around 6,000 degrees Celsius

14. Chromosphere • Above the photosphere is the chromopshere • It’ temperature is 20,000 degrees Celsius • Reddish in color

15. Corona • Largest layer of the sun • Extends millions of kilometers in to space • Hottest layer • Temp= 2,000,000 C° • Charged particles leave the corona creating a solar wind

16. The Coronaseen during an eclipse

17. What are the Layer’s of the Sun? • Core- produces energy from _______ Fusion • Radiative Zone • Convection Zone • Photosphere- gives off light, surface of the sun • Chromosphere • Corona- seen during an_____, gives off solar wind Answer Bank stars Transfer Cool hydrogen 4 eclipse

18. Sunspots • “Cool” dark areas on the Sun’s surface • By studying sunspots, we have discovered that the Sun rotates • Sunspots can last from a few days to a few months • They represent areas of intense Magnetic activity

19. Sunspots • “Cool” dark areas on the Sun’s surface • By studying sunspots, we have discovered that the Sun rotates • Sunspots can last from a few days to a few months • They represent areas of intense Magnetic activity

20. Sunspot CycleMaximums and Minimums • Every 11 years our sun goes through a Sunspot cycle • Our Sun has periods of sunspot maximums where many sunspots are visible • Our Sun also has periods of sunspot minimums where only a few sunspots are visible

21. Solar Flares • A solar flare is a violent explosion in the Sun's atmosphere • They release tremendous amount of radiation or energy in the form of UV Rays, X-rays, and gamma rays

22. Prominences • Prominences are huge arching columns of gas on the surface of the sun • They erupt at speeds ranging from 600-1000 km/s • Ultraviolet light and x-rays from prominences can reach earth and cause disruption in radio signals

23. What Features can be found on the Sun? • Sunspots • _____dark areas on the surface of the sun that occur in an 11 year cycle (maximums/minimums) • Prominences • Huge arching columns of gas • Solar Flares • violent ____ of energy (radiation) Answer Bank stars Transfer bursts Cool photosphere 4

24. Summarize: • Our sun is a star made mostly of ______ and helium gases • _____ is the combining of lighter elements to form _____ elements • In the Sun’s____, 4 hydrogen atoms a combine to form 1 ____ atom & energy is released Answer Bank heavier Hydrogen fusion Helium core

25. Unit: Stars & Galaxies Topic:Light years & Stars • Objectives: Day 2 of 4 • I will understand the concept of a light year and how we use them to measure distances to Stars and galaxies • I will understand how stars vary in their size, color, temperature and brightness • I will learn how to classify stars on a H-R Diagram

26. Quickwrite: Answer one of the questions below in 1-2 sentences: • If you were traveling at the speed of light, how many times do you think you could go around the earth in one second???? • If a star 10 light years away exploded today, how long would it take you to see it???? • Compared to other stars, do you think our sun is hot or cool star??? Large or small star????

27. Light Years • When astronomers first realized how far away stars actually are, it became apparent that a new unit of measurement would be needed to record their distances • Stars are much farther away than the planets in our solar system • Distances between stars are measured in light years!

28. Light Years • A light year is the distance that light travels in a year • We use the light year to measure very distant objects such as stars and galaxies • Light travels at 300,000 km/s or about 9,500,000,000,000 trillion kilometers in one year (9.5 x 1012 km/yr) 299 ,792 km/ s • Nothing is faster than light • If you travel at the speed of light, you would become light

29. How Fast is That? • A traveler, moving at the speed of light, would circum-navigate the equator approximately 7.5 times in one second • How long do you think it takes light to reach Earth from the Sun?

30. What are Light Years? • A light yr is the distance that light travels in a ______ • In 1 yr, light travels 9.5 trillion kilometers or 300,000 km/s • Light years are used to measure very distant objects such as stars and galaxies Answer Bank Average Temperature Absolute Distance Year 90% hot

31. Parallax! • How do we know the stars are farther away than the planets in our solar system? We use parallax! • The distance of a star is found by using parallax • Parallax is the apparent shift in the position of an object when viewed from two different positions • You can easily observe parallax • Hold your hand at arm’s length and look at one finger with your left eye and then with your right eye • What you will notice is that your finger appears to change position with respect to the background

32. Parallax Continued….. • Now try the same experiment with your finger closer to your face • What do you observe? • The closer an object is to the observer, the greater its parallax • We can measure parallax of relatively close stars in order to determine their distance from earth

33. Calculating Parallax

35. What is Parallax? • Parallax is how we measure the ____ to stars in light years • It is found by viewing an object from 2 fixed locations Answer Bank Average Temperature Absolute Distance Year 90% hot

36. Star Characteristics Yellow Stars like are Sun are average in brightness & temperature Blue Stars are large hot and bright Red Stars are small cool and dim

37. What’s the relationship between star color, size, & temperature? • Large Blue-white stars are ___ & bright • Red stars are cool & dim • Yellow stars, like our sun are ____ in temperature and bright ness Answer Bank Average Temperature Absolute Distance Year 90% hot

38. H-R Diagram • In the early 1900’s, Ejnar Hertzsprung and Henry Russell found a way to classify stars • They classified stars by their temperature and brightness http://www.youtube.com/watch?v=HEheh1BH34Q&feature=fvw Blue Massive Stars Supergiants Giants Sun Hot White Dwarfs Red Dwarfs Hot Bright Blue Stars Cool Red Dim Stars Yellow Orange Average Stars

39. H-R Diagram • Hertzsprung and Russell came up with a graph that shows the relationship between temperature and brightness • Notice where the cool small red dwarfs stars are located • Notice where the massive hot blue dwarfs stars are located Blue Massive Stars Supergiants Giants Sun Hot White Dwarfs Red Dwarfs Hot Bright Blue Stars Cool Red Dim Stars Yellow Orange Average Stars

40. What is the H-R Diagram? • A graph that compares the brightness, ______ and color of a star • _____ magnitude is the true brightness of a star Answer Bank Average Temperature Absolute Distance Year 90% hot

41. Main Sequence Stars Blue Massive Stars • Our sun is a yellow Main Sequence Star • Main Sequence Stars that fit into a diagonal band that run from the upper left to the lower right corner • Main Sequence Stars contain large, hot blue stars, as well as small cool red stars • 90 % of all stars are Main Sequence Sun Red Dwarfs Hot Bright Blue Stars Cool Red Dim Stars Yellow Orange Average Stars

42. What are Main Sequence Stars? • The diagonal band of stars in an H-R diagram • Blue, white, yellow, orange, red stars • ____ of the stars we see at night are main sequence Answer Bank Average Temperature Absolute Distance Year 90% hot

43. Summarize: • _______ is how we measure star distances when viewed from two fixed locations as we orbit the sun • Large stars are ____ and small stars are ____ • Hot stars are ______ in color • Cooler stars are ______in color • An H-R diagram is a graph that relates star ________ to star ________ Answer Bank Brightness temperature Parallax bright Absolute blue red dim

44. Unit:Stars & Galaxies Topic:Star Lifecycle • Objectives: Day 3 of 4 • To learn the difference between the lifecycle of a massive blue main sequence star with a yellow main sequence star like our sun • To understand how nucleosynthesis occurs in stars • Star size: http://www.youtube.com/watch?v=HEheh1BH34Q

45. Quickwrite: Answer one of the questions below in 1-2 sentences: • What do you think will happen to our Sun when it runs out of hydrogen fuel????? • Everything around us is made of elements. Where do you think these elements are made???? • Why do you think some star’s become black hole’s and other like Sun do not????

46. Star Size All star’s form in a nebula A star will begin it’s main sequence when hydrogen fusion begins But what determines the size of a star? Gravity wants to crush the star So why doesn’t it? Because the outward pressure Or force of energy from Fusion balances out the inward force of gravity This keeps the star in a state of balance or equilibrium!

47. What determines the size of a main sequence star? • A balance between the ____ pull of gravity and the outward push of energy created by fusion Answer Bank Neutron Lighter Inward Red Fusion White dwarf short

48. Hydrogen Temperature & PressureAffect Star Life Empty Full Hydrogen Large massive blue stars have Short lives Because they have higher pressures & temperatures in the Core, therefore they run through their Hydrogen fuel source faster Hydrogen Empty Full Star like our sun have average lives Empty Full Small Red dwarf stars have long lives because of cooler temperatures in the core

49. How does temperature and pressure effect the life of a star? • Temperature and pressure increase the rate of fusion in a stars core • Hot blue stars have ____ lives • Cooler ___ stars have long lives • Yellow stars like our sun have average lives Answer Bank Neutron Lighter Inward Red Fusion White dwarf short

50. Massive Blue Star Lifecycle In a massive blue stars core, hydrogen fuses together to form Helium for most of its short Main sequence life Eventually hydrogen starts to run out and helium starts to accumulate As a result gravity wants to crush the star, pressures & temperatures increase, & the star begins fusing helium into carbon Carbon Helium Helium Over time the outward pressure or force of energy from fusion becomes stronger than the inward force of gravity & the star begins to swell & cool changing its color in the process