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Stars Chap. 30 The Sun 30.1 Measuring Stars 30.2 Stellar Evolution 30.3.

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Presentation on theme: "Stars Chap. 30 The Sun 30.1 Measuring Stars 30.2 Stellar Evolution 30.3."— Presentation transcript:

1 Stars Chap. 30 The Sun 30.1 Measuring Stars 30.2 Stellar Evolution 30.3

2 The Sun 30.1 Objectives explore the structure of the Sun describe the solar activity cycle and how the Sun affects the Earth compare the different types of spectra

3 I.How do we learn about it?

4 A.Using solar observatories Dunn Solar Telescope Sacramento Peak, NM

5 I.How do we learn about it? Solar Heliospheric Observatory (SOHO) A.Using solar observatories B.Using satellites

6 II.Properties

7 A.The Sun has a very large radius Radius Sun: 695,000 km Earth: 6,400 km

8 II.Properties A.The Sun has a very large radius B.The Sun is very massive Mass Sun: 2.0 x kg Earth: 6.0 x kg

9 II.Properties A.The Sun has a very large radius B.The Sun is very massive C.The density is similar to that of the gas giant planets.

10 II.Properties A.The Sun has a very large radius B.The Sun is very massive C.The density is similar to that of the gas giant planets. 1.Outer portion is not very dense

11 II.Properties A.The Sun has a very large radius B.The Sun is very massive C.The density is similar to that of the gas giant planets. 1.Outer portion is not very dense 2.Inner portion is much denser

12 II.Properties A.The Sun has a very large radius B.The Sun is very massive C.The density is similar to that of the gas giant planets. D.Physical state of matter:.

13 II.Properties A.The Sun has a very large radius B.The Sun is very massive C.The density is similar to that of the gas giant planets. D.Physical state of matter: plasma.

14 III. Layers of Atmosphere

15 A.Photosphere

16 III. Layers of Atmosphere A.Photosphere 1.Lowest layer 2.Only about 400 km thick 3.Average temp: 5800 K 4.Emits light we can see

17 III. Layers of Atmosphere A.Photosphere B.Chromosphere

18 III. Layers of Atmosphere A.Photosphere B.Chromosphere 1.Thicker layer (about 2500 km) 2.Hotter (average temp: 30,000 K) 3.Difficult to see, except during eclipse

19 III. Layers of Atmosphere A.Photosphere B.Chromosphere C.Corona

20 III. Layers of Atmosphere A.Photosphere B.Chromosphere C.Corona 1.Outermost layer 2.Extends several million km 3.Very hot (1 to 2 million K)

21 IV. Solar Activity Caused when sun’s magnetic field interrupts its atmosphere

22 IV. Solar Activity A.Solar Wind

23 IV. Solar Activity A.Solar Wind 1.Charged particles from sun traveling at high speeds (400 km/s)

24 IV. Solar Activity A.Solar Wind 1.Charged particles from sun traveling at high speeds (400 km/s) 2.Deflected by our magnetic field

25 IV. Solar Activity A.Solar Wind 1.Charged particles from sun traveling at high speeds (400 km/s) 2.Deflected by our magnetic field 3.Causes auroras

26 IV. Solar Activity A.Solar Wind B.Sun Spots

27 IV. Solar Activity A.Solar Wind B.Sun Spots 1.Appear on photosphere

28 IV. Solar Activity A.Solar Wind B.Sun Spots 1.Appear on photosphere 2.Look dark because they are cooler

29 IV. Solar Activity A.Solar Wind B.Sun Spots 1.Appear on photosphere 2.Look dark because they are cooler 3.Associated with solar wind

30 IV. Solar Activity A.Solar Wind B.Sun Spots C.Solar Flares

31 IV. Solar Activity A.Solar Wind B.Sun Spots C.Solar Flares 1.Violent eruptions from surface

32 IV. Solar Activity A.Solar Wind B.Sun Spots C.Solar Flares 1.Violent eruptions from surface 2.Occur in corona

33 IV. Solar Activity A.Solar Wind B.Sun Spots C.Solar Flares 1.Violent eruptions from surface 2.Occur in corona 3.Some the size of Earth

34 IV. Solar Activity D.Solar Prominence

35 IV. Solar Activity D.Solar Prominence 1.Less violent than flares

36 IV. Solar Activity D.Solar Prominence 1.Less violent than flares 2.Cool sheets of gas that condense from corona

37 IV. Solar Activity 1.Less violent than flares 2.Cool sheets of gas that condense from corona 3.Some rain back material on surface D.Solar Prominence

38 V. Interior of Sun

39 A.Core

40 V. Interior of Sun 1.Site of fusion (energy production) 2.Density of 160 g/cm 3 (15 x denser than lead) 3.Temperature of about 15 million K 4.Extends 25% to outside A.Core

41 V. Interior of Sun A.Core B.Radiative Zone

42 V. Interior of Sun A.Core B.Radiative Zone 1.Extends another 60% to outside 2.Temp. is about 2 million K 3.Passes energy (photons) from atom to atom

43 V. Interior of Sun A.Core B.Radiative Zone C.Convective Zone

44 V. Interior of Sun A.Core B.Radiative Zone C.Convective Zone 1.Final 15% 2.Energy is carried via moving gas volumes 3.Temp. is about 5700 K

45 VI. Fusion

46 A.Joining of nuclei

47 VI. Fusion A.Joining of nuclei B.Occurs at very high temp./pressure

48 VI. Fusion A.Joining of nuclei B.Occurs at very high temp./pressure C.Opposite of fission

49 VI. Fusion A.Joining of nuclei B.Occurs at very high temp./pressure C.Opposite of fission D.Mass is lost during process E = mc 2

50 VI. Fusion A.Joining of nuclei B.Occurs at very high temp./pressure C.Opposite of fission D.Mass is lost during process E.Tremendous amount of energy produced 1354 J/m 2

51 VII. Three types of Spectra

52 A.Continuous spectra Shows all the colors with no breaks

53 VII. Three types of Spectra A.Continuous spectra B.Emission spectra Only certain lines produced (depending on elements present

54 VII. Three types of Spectra A.Continuous spectra B.Emission spectra C.Absorption spectra Light passes through a gas and some of it is absorbed (leaving dark, ‘missing’ sections)

55 VIII. Composition of Sun

56 A.Hydrogen (70%)

57 VIII. Composition of Sun A.Hydrogen (70%) B.Helium (28%)

58 VIII. Composition of Sun A.Hydrogen (70%) B.Helium (28%) C.Trace elements (O, C, Ne, Fe, N, Si, Mg, S)

59 The End

60 Measuring the Stars – 30.2 Objectives describe star distribution and distance classify the types of stars summarize the interrelated properties of stars

61 I.Groups of stars Pleiades

62 A.Constellations Groups of stars named after animals/mythological creatures

63 I.Groups of stars Orion A.Constellations

64 I.Groups of stars Orion A.Constellations Betelgeuse Rigel

65 I.Groups of stars A group of stars that are bound by gravity A.Constellations B.Star Clusters

66 I.Groups of stars Stars are loosely bound by gravity A.Constellations B.Star Clusters 1.Open cluster Pleiades

67 I.Groups of stars Tightly bound stars, relatively close together A.Constellations B.Star Clusters M13, in Hercules 1.Open cluster 2.Globular cluster

68

69 I.Groups of stars Two stars that are gravitationally bound. A.Constellations B.Star Clusters C.Binaries Algol – a blue dwarf

70 II.Stellar Positions and Distances

71 A.Stellar distance

72 II.Stellar Positions and Distances The distance traveled by light in one year. A.Stellar distance 1.Light year (ly)

73 Calculate this! Light travels at a speed of 300,000 km/s. How many miles is a light year?

74 Calculate this! Proxima Centauri is 4.24 light years. How many kilometers is this star?

75 II.Stellar Positions and Distances The distance of a star when it appears to shift one second of a degree due to parallax. 1 pc = 3.26 ly. A.Stellar distance 1.Light year (ly) 2.Parsec (pc)

76 II.Stellar Positions and Distances The apparent shift in position of an object as the observer’s location changes A.Stellar distance 1.Light year (ly) 2.Parsec (pc) 3.Parallax

77 Calculate this! The brightest star in the sky (besides the Sun) is Sirius. It is 2.6 pc from Earth. How long does it take light from Sirius to reach us?

78 II.Stellar Positions and Distances B.Other Properties of Stars

79 II.Stellar Positions and Distances B.Other Properties of Stars 1.Apparent Magnitude How bright a star appears. (affected by luminosity and distance)

80 Magnitude The lower the number the brighter the object. Each value increase equates to about decrease in brightness.

81 Magnitude of celestial objects

82 II.Stellar Positions and Distances B.Other Properties of Stars 1.Apparent Magnitude 2.Absolute Magnitude How bright a star would appear at 10 pc. ( This can be calculated if you know the actual distance.)

83 II.Stellar Positions and Distances B.Other Properties of Stars 1.Apparent Magnitude 2.Absolute Magnitude 3.Luminosity The energy output from the surface of a star. Can be measured in joules/second or watts.

84 II.Stellar Positions and Distances B.Other Properties of Stars 1.Apparent Magnitude 2.Absolute Magnitude 3.Luminosity 4.Spectra of Stars The types (colors) of light given off

85 II.Stellar Positions and Distances B.Other Properties of Stars 1.Apparent Magnitude 2.Absolute Magnitude 3.Luminosity 4.Spectra of Stars Cooler stars have more lines in spectra a.Determined by temperature

86 II.Stellar Positions and Distances B.Other Properties of Stars 1.Apparent Magnitude 2.Absolute Magnitude 3.Luminosity 4.Spectra of Stars O5, A4, A5, G2 (sun), etc. a.Determined by temperature b.Given a letter & number ranking

87

88 II.Stellar Positions and Distances B.Other Properties of Stars 1.Apparent Magnitude 2.Absolute Magnitude 3.Luminosity 4.Spectra of Stars a.Determined by temperature b.Given a letter & number ranking c.Light spectra can shift due to motion

89 II.Stellar Positions and Distances B.Other Properties of Stars 1.Apparent Magnitude 2.Absolute Magnitude 3.Luminosity 4.Spectra of Stars 5.H-R diagram (Hertzsprung-Russell) Used to classify stars based on spectra & magnitude

90

91 The End

92 Stellar Evolution – 30.3 Objectives Explain how astronomers learn about the internal structure of stars Describe how the Sun will change during its lifetime and how it will end Compare the evolutions of stars of different masses

93 I.Introduction

94 A.A star is balances two forces

95 I.Introduction A.A star is balances two forces 1.Inward force: 1.Inward force:.

96 I.Introduction A.A star is balances two forces 1.Inward force: gravity 2.Outward force: _________________

97 I.Introduction A.A star is balances two forces 1.Inward force: gravity 2.Outward force: fusion and radiation

98 I.Introduction B.Structure of a star depends on:

99 I.Introduction Elements a star is made of 1.Composition B.Structure of a star depends on:

100 I.Introduction The total amount of material in a star 1.Composition 2.Mass B.Structure of a star depends on:

101 I.Introduction Pull inward which is balanced by force outward 1.Composition 2.Mass Gravity B.Structure of a star depends on:

102 I.Introduction Higher temperature counter higher gravity. 1.Composition 2.Mass Gravity Temperature B.Structure of a star depends on:

103 I.Introduction When temperatures increase so do reaction rates. 1.Composition 2.Mass Gravity Temperature Rate of Fusion B.Structure of a star depends on:

104 I.Introduction Star produces more energy, and is brighter. 1.Composition 2.Mass Gravity Temperature Rate of Fusion Luminosity B.Structure of a star depends on:

105 II.Fusion Energy producing reaction in stars

106 II.Fusion Most stars fall in this category A.Main sequence stars

107 II.Fusion 1.Start by fusing H + H to He A.Main sequence stars

108 II.Fusion 1.Start by fusing H + H to He 2.He + He + He to C A.Main sequence stars

109 II.Fusion 1.Start by fusing H + H to He 2.He + He + He to C 3.He + C to oxygen A.Main sequence stars

110 II.Fusion 1.Start by fusing H + H to He 2.He + He + He to C 3.He + C to oxygen 4.He + O to neon A.Main sequence stars

111 II.Fusion 1.Start by fusing H + H to He 2.He + He + He to C 3.He + C to oxygen 4.He + O to neon 5.He + Ne to magnesium A.Main sequence stars

112 II.Fusion 1.Start by fusing H + H to He 2.He + He + He to C 3.He + C to oxygen 4.He + O to neon 5.He + Ne to magnesium 6.This stops at iron because fusion of larger elements is no longer favorable. A.Main sequence stars

113 III. Life cycle of Sun

114 A.Star formation

115 III. Life cycle of Sun 1.Nebula collapses on itself from its own gravity A.Star formation Nebula is an interstellar cloud of gas and dust Orion Nebula

116 III. Life cycle of Sun 1.Nebula collapses on itself from its own gravity 2.Protostar forms in center of disk shape, emitting lots of infrared light A.Star formation

117 III. Life cycle of Sun B.Fusion begins...

118 III. Life cycle of Sun B.Fusion begins... 1.when minimum temperature is reached

119 III. Life cycle of Sun B.Fusion begins... 1.when minimum temperature is reached 2.this often illuminates surrounding gases Rosette Nebula

120 III. Life cycle of Sun B.Fusion begins... 1.when minimum temperature is reached 2.this often illuminates surrounding gases 3.star enters main-sequence phase – primarily converting H to He.

121 True or False? Large main-sequence stars last longer than smaller main-sequence stars.

122 True or False? Large main-sequence stars last longer than smaller main-sequence stars. False – larger stars get hotter, and use their fuel up faster.

123 III. Life cycle of Sun C.Becoming a Red Giant A larger, cooler star that is very luminous. Betelgeuse

124 III. Life cycle of Sun C.Becoming a Red Giant 1.After about 10 billion years, hydrogen is used up

125 III. Life cycle of Sun C.Becoming a Red Giant 1.After about 10 billion years, hydrogen is used up 2.Core of star is made of He

126 III. Life cycle of Sun C.Becoming a Red Giant 1.After about 10 billion years, hydrogen is used up 2.Core of star is made of He 3.Layer of gas surrounding core does fusion, causing gases to expand and cool

127 III. Life cycle of Sun C.Becoming a Red Giant 1.After about 10 billion years, hydrogen is used up 2.Core of star is made of He 3.Layer of gas surrounding core does fusion, causing gases to expand and cool 4.Outer layers are driven away due to decrease in surface gravity

128 III. Life cycle of Sun C.Becoming a Red Giant 1.After about 10 billion years, hydrogen is used up 2.Core of star is made of He 3.Layer of gas surrounding core does fusion, causing gases to expand and cool 4.Outer layers are driven away due to decrease in surface gravity 5.He in core reacts to form C

129 III. Life cycle of Sun D.Becoming a White Dwarf

130 III. Life cycle of Sun D.Becoming a White Dwarf 1.Star is not big enough to further react carbon

131 III. Life cycle of Sun D.Becoming a White Dwarf 1.Star is not big enough to further react carbon 2.Gases surrounding star expend and are driven off

132 III. Life cycle of Sun D.Becoming a White Dwarf 1.Star is not big enough to further react carbon 2.Gases surrounding star expend and are driven off 3.Core remains as small, hot, earth- sized object

133 III. Life cycle of Sun D.Becoming a White Dwarf 1.Star is not big enough to further react carbon 2.Gases surrounding star expend and are driven off 3.Core remains as small, hot, earth- sized object 4.This star is made of carbon

134 IV. Massive Stars Monocerotis

135 A.Same beginning – but hydrogen fusion happens quickly

136 IV. Massive Stars A.Same beginning – but hydrogen fusion happens quickly B.Star expands and contracts to repeatedly, forming variety of elements (not bigger than Fe)

137 IV. Massive Stars A.Same beginning – but hydrogen fusion happens quickly B.Star expands and contracts to repeatedly, forming variety of elements (not bigger than Fe) C.Mass if lost by stellar wind

138 IV. Massive Stars D.Size determines fate

139 IV. Massive Stars D.Size determines fate 1.If star’s mass is < 1.4 x Sun’s size it becomes a white dwarf.

140 IV. Massive Stars D.Size determines fate 1.If star’s mass is < 1.4 x Sun’s size it becomes a white dwarf. 2.If star’s mass is > 1.4 x Sun’s size it’s gravity pulls gases inward, merging protons and electrons in.

141 IV. Massive Stars D.Size determines fate 1.If star’s mass is < 1.4 x Sun’s size it becomes a white dwarf. 2.If star’s mass is > 1.4 x Sun’s size it’s gravity pulls gases inward, merging protons and electrons in neutrons.

142 IV. Massive Stars D.Size determines fate 1.If star’s mass is < 1.4 x Sun’s size it becomes a white dwarf. 2.If star’s mass is > 1.4 x Sun’s size it’s gravity pulls gases inward, merging protons and electrons in neutrons. a.These are neutron stars

143 IV. Massive Stars D.Size determines fate 1.If star’s mass is < 1.4 x Sun’s size it becomes a white dwarf. 2.If star’s mass is > 1.4 x Sun’s size it’s gravity pulls gases inward, merging protons and electrons in neutrons. a.These are neutron stars b.They are very dense – 3x Sun’s mass squeezed into 10 km radius.

144 IV. Massive Stars D.Size determines fate 1.If star’s mass is < 1.4 x Sun’s size it becomes a white dwarf. 2.If star’s mass is > 1.4 x Sun’s size it’s gravity pulls gases inward, merging protons and electrons in neutrons. a.These are neutron stars b.They are very dense – 3x Sun’s mass squeezed into 10 km radius. c.Particles from outer layer bounce off neutron star creating supernova

145 IV. Massive Stars D.Size determines fate 1.If star’s mass is < 1.4 x Sun’s size it becomes a white dwarf. 2.If star’s mass is > 1.4 x Sun’s size it’s gravity pulls gases inward, merging protons and electrons in neutrons. 3.If star’s mass is 3 x Sun’s size it becomes a black hole.

146 The End


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