# Ay 1 Lecture 8. Stellar Structure and the Sun

Size: px
Start display at page:

Transcription

1 Ay 1 Lecture 8 Stellar Structure and the Sun

2 8.1 Stellar Structure Basics

3 How Stars Work Hydrostatic Equilibrium: gas and radiation pressure balance the gravity Thermal Equilibrium: Energy generated = Energy radiated Thermonuclear Reactions: The source of the energy Energy Transport: How does it get from the core to the surface

4 Equations of the Stellar Structure Mass vs. radius: dm = 4πr 2 ρdr dm dr = 4πr2 ρ R M r dr m dm ρ Luminosity vs. radius: dl = 4πr 2 ρdr q dl dr = 4πr2 ρq q = rate of energy generation per unit mass

5 Hydrostatic Equilibrium At a given radius, the gravitational force on a shell is: F g = GmΔm r 2 R M r dr m dm ρ The weight of that mass shell over the area has to be the difference between the pressures on an inner and an outer surface of the shell. dm = 4πr 2 ρdr dp dr = Gm r 2 ρ

6 Pressure of What? Total pressure: P = P gas + P radiation The equation of state for an ideal gas is: P gas = nkt n = the number of particles per unit volume (ions and electrons) Or: ρ = mass density m H = the mass of hydrogen atom μ = average particle mass in units of m H Depends on the chemical composition. Typically μ ~ 0.8 P gas = The ideal gas constant: Thus: ρ µm H kt R k m H P gas = R µ ρt

7 Radiation Pressure Momentum exchange between photons and electrons/ions results in a radiation pressure For blackbody radiation: P r = 1 3 at 4 where a is the radiation constant: a = 8π 5 k 4 15c 3 h 3 = 4σ c = erg cm -3 K -4 Radiation pressure dominates over the gas pressure inside very massive stars, which are hotter

8 Equations of Stellar Structure At radius r in a static, spherically symmetric star and the density ρ: dm dr = 4πr2 ρ dp dr = Gm r 2 ρ dt dr = 3 4ac dl dr = 4πr2 ρq κρ T 3 L 4πr 2 Mass conservation Hydrostatic equilibrium Energy transport due to radiation (only) Energy generation 4 equations with 4 unknowns - enough for a solution once we know P(ρ,T), opacity κ, and q

9 Some Order-of-Magnitude Estimates Let s see if we can estimate roughly the conditions in the Solar core. Pressure P = F / A: F G M 2 / R 2 A 4 π R 2 P G M 2 / 4 π R 4 (M g, R cm, G cgs) Thus: P est ~ dyn / cm 2 -- and surely an underestimate True value: P c dyn / cm 2 Now the temperature: 3/2 k T G m p M / R ( k erg/k, m p g ) Thus: T est K True value: T c K -- not bad!

10 Standard Solar Model

11 Standard Solar Model

12 8.2 Energy Generation in Stars

13 Energy Production in Stars: Thermonuclear Reactions Mass of nuclei with several protons and / or neutrons does not exactly equal mass of the constituents - slightly smaller because of the binding energy of the nucleus The main process is hydrogen fusion into helium: 4 protons, total mass = = amu 4 1 H 4 He + photons and neutrinos helium nucleus, mass = amu Mass difference: amu = 4.7 x g ΔE = ΔMc 2 = erg = 27 MeV Or about 0.7% of the total rest mass

14

15

16

17 The P-P Cycle

18 Binding Energy Per Nucleon vs. Atomic Number Energetically favorable Energetically unfavorable Most bound nucleus is iron 56: up to A < 56 fusion releases energy, but A > 56 fusion requires energy input

19 Overcoming the Electrostatic Barrier Energy potential E(r) Coulomb barrier + At r = r 0, height of the Coulomb barrier is: E = Z 1 Z 2 e2 r 0 ~ Z 1 Z 2 MeV r 0 r Most particles have too low Nuclear strong Electrostatic thermal energies to overcome interactions repulsion the Coulomb barrier! What makes the fusion possible is the quantum tunneling effect Probability of tunneling increases steeply with particle energy

20 The Gamow Peak The most energetic nuclei are the most likely to fuse, but very few of them in a thermal distribution of particle speeds: Number of particles Gamow peak P for fusion Particle energy Narrow range of energies around the Gamow peak where significant numbers of particles in the plasma are able to fuse. Energy is >> typical thermal energy, so fusion is slow

21 Thermonuclear Reactions (TNR) Burning of H into He is the only energy generation process on the Main Sequence, where stars spend most of their lives; all others happen in post-ms evolutionary stages Solar luminosity ~ 4.3 million tons of H into He per second In addition to the p-p cycle, there is the CNO Cycle, in which the C, N, O, nuclei catalyze the burning of H into He The rates of TNR are usually very steep functions of temperature, due to high potential barriers Generally, more massive stars achieve higher T c, and can synthesize elements up to Fe; beyond Fe, it happens in SN explosions

22 Self-Regulation in Stars Suppose the fusion rate increases slightly. Then, (1) Temperature increases (2) Pressure increases (3) Core expands (4) Density and temperature decrease (5) Fusion rate decreases So there's a feedback mechanism which prevents the fusion rate from skyrocketing upward This is the inverse of the core collapse mechanism discussed for the protostars

23 8.3 Energy Transport in Stars

24 Energy Transport Mechanisms in Stars How does the energy get out? 1. Radiatively (photon diffusion) 2. Convectively 3. Conduction (generally not important in stars) and the reality is fairly complex

25 Radiative Energy Transfer As the heat diffuses from the core outwards, the photons are scattered by the dense plasma inside the star For the Sun, it takes ~ 250,000 years for the energy to reach the surface The opacity of the plasma depends on the temperature, density, and chemical composition If the plasma is too opaque, convection becomes a more efficient mechanism for the energy transfer

26 When Does the Convection Happen? The Schwarzschild criterion: Imagine displacing a small mass element vertically upward by a distance dr. Assume that no heat is exchanged with the surrounding, i.e. the process is adiabatic: Element expands to stay in pressure balance New density will not generally equal the new ambient density If this mechanical energy transport is more efficient than the radiative case, the medium will be convectively unstable

27 8.4 The Sun, Our Star

28 Why Study the Sun? The nearest star - can study it in a greater detail than any others. This can help us understand better the overall stellar physics and phenomenology Radiation transfer, convection Photospheric and chromospheric activity Kind of important for the life on Earth Solar activity has terrestrial consequences A gateway to the neutrino astronomy (and physics) Thermometry of stellar cores and the standard model Neutrino oscillations

29 A Theoretical Model of the Energy The core is surrounded by a radiative zone extending to about 0.71 solar radius. Energy transfer through radiative diffusion The radiative zone is surrounded by a rather opaque convective zone of gas at relatively low temperature and pressure. Energy transfer through convection Transfer in the Sun Hydrogen fusion takes place in a core extending out to about 0.25 solar radius

30 We can probe the solar interior using the Sun s own vibrations Helioseismology is the study of how the Sun vibrates These vibrations have been used to infer pressures, densities, chemical composition, and rotation rates within the Sun Major contributions from Caltech (Libbrecht et al.)

31 Rotation of the Solar Interior

32 Solar Atmosphere / Surface Layers The Sun s atmosphere has three main layers: 1. the photosphere 2. the chromosphere 3. the corona The visible surface of the Sun, the photosphere, is the lowest layer in the solar atmosphere

33 Emergent spectrum of the photosphere is close to a blackbody T ~ 5800 K

34 Convection in the photosphere produces granules

35 Sunspots are low-temperature regions in the photosphere

36 Sunspots come in groups, and follow the Sun s differential rotation. They start from the higher latitudes and migrate towards the Solar equator. They correlate well with other manifestations of the Solar activity.

37 The Sun s surface features (including sunspot numbers) vary in an 11-year cycle; it is really a 22-year cycle in which the surface magnetic field increases, decreases, and then increases again with the opposite polarity There are probably also longer period cycles

38

39 Note the scale: Earth s diameter is < 1% of the Solar diameter

40 Activity in the corona includes coronal mass ejections and coronal holes

41 The Sun s magnetic field also produces A solar flare is a brief eruption of hot, ionized gases from a sunspot group A coronal mass ejection is a much larger eruption that involves immense amounts of gas from the corona other forms of solar activity

42 The Sun is Now Being Monitored by a Number of Satellites and Ground-Based Observatories SOHO far-uv composite Yohkoh soft X-ray

43 Solar Neutrinos and the Birth of Neutrino Astronomy Detection of Solar neutrinos offers a unique probe of deep stellar interiors - a fundamental test of our understanding of stars and their energy production For many years, there was a factor of 3 discrepancy between the theoretical predictions and the experiment (the Solar neutrino problem ). The resolution of it provided a fundamental physical insight (neutrino oscillations)

44 Neutrinos from the main p-p chain are of very low energy. Less important reactions (energetically) yield a smaller flux of higher energy neutrinos: p + e + p 2 H + ν e Solar Neutrino Flux `pep MeV neutrino 3 He + p 4 He + e + + ν e e + 7 Be 7 Li + ν e 8 B 8 Be + e + + ν e MeV 0.383, MeV 0-15 MeV Since we get 2 neutrinos for each 28 MeV of energy, we can use Solar luminosity to calculate neutrino flux at Earth: Neutrino flux = 2L sun 28 MeV 1 4πd 2 ~ neutrinos/s/cm 2

45 Homestake Mine Detector First attempt to detect Solar neutrinos began in the 1960s: Detector is a large tank containing 600 tons of C 2 Cl 4, situated at 1500m depth in a mine in South Dakota. Neutrinos interact with the chlorine to produce a radioactive isotope of argon: ν e + 37 Cl e Ar + an electron which is not observed.

46 Super Kamiokande Measure: ν e + e ν e + e look for Cherenkov radiation from high energy electrons in water

### 9-1 The Sun s energy is generated by thermonuclear reactions in its core The Sun s luminosity is the amount of energy emitted each second and is

1 9-1 The Sun s energy is generated by thermonuclear reactions in its core The Sun s luminosity is the amount of energy emitted each second and is produced by the proton-proton chain in which four hydrogen

### An Overview of the Details

Guiding Questions The Sun Our Extraordinary Ordinary Star 1. What is the source of the Sun s energy? 2. What is the internal structure of the Sun? 3. How can astronomers measure the properties of the Sun

### The Sun Our Extraordinary Ordinary Star

The Sun Our Extraordinary Ordinary Star 1 Guiding Questions 1. What is the source of the Sun s energy? 2. What is the internal structure of the Sun? 3. How can astronomers measure the properties of the

### An Overview of the Details

The Sun Our Extraordinary Ordinary Star 1 Guiding Questions 1. What is the source of the Sun s energy? 2. What is the internal structure of the Sun? 3. How can astronomers measure the properties of the

### The Sun. The Sun is a star: a shining ball of gas powered by nuclear fusion. Mass of Sun = 2 x g = 330,000 M Earth = 1 M Sun

The Sun The Sun is a star: a shining ball of gas powered by nuclear fusion. Mass of Sun = 2 x 10 33 g = 330,000 M Earth = 1 M Sun Radius of Sun = 7 x 10 5 km = 109 R Earth = 1 R Sun Luminosity of Sun =

### Announcements. - Homework #5 due today - Review on Monday 3:30 4:15pm in RH103 - Test #2 next Tuesday, Oct 11

Announcements - Homework #5 due today - Review on Monday 3:30 4:15pm in RH103 - Test #2 next Tuesday, Oct 11 Review for Test #2 Oct 11 Topics: The Solar System and its Formation The Earth and our Moon

### Chapter 8 The Sun Our Star

Note that the following lectures include animations and PowerPoint effects such as fly ins and transitions that require you to be in PowerPoint's Slide Show mode (presentation mode). Chapter 8 The Sun

### The Sun Our Star. Properties Interior Atmosphere Photosphere Chromosphere Corona Magnetism Sunspots Solar Cycles Active Sun

The Sun Our Star Properties Interior Atmosphere Photosphere Chromosphere Corona Magnetism Sunspots Solar Cycles Active Sun General Properties Not a large star, but larger than most Spectral type G2 It

### Introduction. Stellar Objects: Introduction 1. Why should we care about star astrophysics?

Stellar Objects: Introduction 1 Introduction Why should we care about star astrophysics? stars are a major constituent of the visible universe understanding how stars work is probably the earliest major

### The Sun. the main show in the solar system. 99.8% of the mass % of the energy. Homework due next time - will count best 5 of 6

The Sun the main show in the solar system 99.8% of the mass 99.9999...% of the energy 2007 Pearson Education Inc., publishing as Pearson Addison-Wesley Homework due next time - will count best 5 of 6 The

### Chapter 14 Lecture. Chapter 14: Our Star Pearson Education, Inc.

Chapter 14 Lecture Chapter 14: Our Star 14.1 A Closer Look at the Sun Our goals for learning: Why does the Sun shine? What is the Sun's structure? Why does the Sun shine? Is it on FIRE? Is it on FIRE?

### Sun s Properties. Overview: The Sun. Composition of the Sun. Sun s Properties. The outer layers. Photosphere: Surface. Nearest.

Overview: The Sun Properties of the Sun Sun s outer layers Photosphere Chromosphere Corona Solar Activity Sunspots & the sunspot cycle Flares, prominences, CMEs, aurora Sun s Interior The Sun as an energy

### Chapter 14 Our Star A Closer Look at the Sun. Why was the Sun s energy source a major mystery?

Chapter 14 Our Star 14.1 A Closer Look at the Sun Our goals for learning Why was the Sun s energy source a major mystery? Why does the Sun shine? What is the Sun s structure? Why was the Sun s energy source

### Stellar Structure. Observationally, we can determine: Can we explain all these observations?

Stellar Structure Observationally, we can determine: Flux Mass Distance Luminosity Temperature Radius Spectral Type Composition Can we explain all these observations? Stellar Structure Plan: Use our general

### Astronomy 1 Fall Reminder: When/where does your observing session meet? [See from your TA.]

Astronomy 1 Fall 2016 Reminder: When/where does your observing session meet? [See email from your TA.] Lecture 9, October 25, 2016 Previously on Astro-1 What is the Moon made of? How did the Moon form?

### Outline. The Sun s Uniqueness. The Sun among the Stars. Internal Structure. Evolution. Neutrinos

Lecture 2: The Sun as a Star Outline 1 The Sun s Uniqueness 2 The Sun among the Stars 3 Internal Structure 4 Evolution 5 Neutrinos What makes the Sun Unique? Some Answers Sun is the closest star Only star

### Agenda for Ast 309N, Sep. 6. The Sun s Core: Site of Nuclear Fusion. Transporting Energy by Radiation. Transporting Energy by Convection

Agenda for Ast 309N, Sep. 6 The Sun s Core: Site of Nuclear Fusion Feedback on card of 9/04 Internal structure of the Sun Nuclear fusion in the Sun (details) The solar neutrino problem and its solution

### Nuclear Reactions and Solar Neutrinos ASTR 2110 Sarazin. Davis Solar Neutrino Experiment

Nuclear Reactions and Solar Neutrinos ASTR 2110 Sarazin Davis Solar Neutrino Experiment Hydrogen Burning Want 4H = 4p è 4 He = (2p,2n) p è n, only by weak interaction Much slower than pure fusion protons

### The Sun. Basic Properties. Radius: Mass: Luminosity: Effective Temperature:

The Sun Basic Properties Radius: Mass: 5 R Sun = 6.96 km 9 R M Sun 5 30 = 1.99 kg 3.33 M ρ Sun = 1.41g cm 3 Luminosity: L Sun = 3.86 26 W Effective Temperature: L Sun 2 4 = 4πRSunσTe Te 5770 K The Sun

### A Closer Look at the Sun

Our Star A Closer Look at the Sun Our goals for learning Why was the Sun s energy source a major mystery? Why does the Sun shine? What is the Sun s structure? Why was the Sun s energy source a major mystery?

### Guidepost. Chapter 08 The Sun 10/12/2015. General Properties. The Photosphere. Granulation. Energy Transport in the Photosphere.

Guidepost The Sun is the source of light an warmth in our solar system, so it is a natural object to human curiosity. It is also the star most easily visible from Earth, and therefore the most studied.

### Astronomy 1 Winter 2011

Astronomy 1 Winter 2011 Lecture 19; February 23 2011 Asteroids Comets Meteors Previously on Astro-1 Homework Due 03/02/11 On your own: answer all the review questions in chapters 16 17 and 18 To TAs: answer

### Chapter 14 Lecture. The Cosmic Perspective Seventh Edition. Our Star Pearson Education, Inc.

Chapter 14 Lecture The Cosmic Perspective Seventh Edition Our Star 14.1 A Closer Look at the Sun Our goals for learning: Why does the Sun shine? What is the Sun's structure? Why does the Sun shine? Is

### THIRD-YEAR ASTROPHYSICS

THIRD-YEAR ASTROPHYSICS Problem Set: Stellar Structure and Evolution (Dr Ph Podsiadlowski, Michaelmas Term 2006) 1 Measuring Stellar Parameters Sirius is a visual binary with a period of 4994 yr Its measured

### Stellar Interior: Physical Processes

Physics Focus on Astrophysics Focus on Astrophysics Stellar Interior: Physical Processes D. Fluri, 29.01.2014 Content 1. Mechanical equilibrium: pressure gravity 2. Fusion: Main sequence stars: hydrogen

### The Sun ASTR /17/2014

The Sun ASTR 101 11/17/2014 1 Radius: 700,000 km (110 R ) Mass: 2.0 10 30 kg (330,000 M ) Density: 1400 kg/m 3 Rotation: Differential, about 25 days at equator, 30 days at poles. Surface temperature: 5800

### The Quiet Sun The sun is currently being studied by several spacecraft Ulysses, SOHO, STEREO, and ACE.

The Quiet Sun The sun is currently being studied by several spacecraft Ulysses, SOHO, STEREO, and ACE. Messenger also contains instruments that can do some solar studies. http://www.stereo.gsfc.nasa.gov

### The Sun. Nearest Star Contains most of the mass of the solar system Source of heat and illumination

The Sun Nearest Star Contains most of the mass of the solar system Source of heat and illumination Outline Properties Structure Solar Cycle Energetics Equation of Stellar Structure TBC Properties of Sun

### Stellar Interiors - Hydrostatic Equilibrium and Ignition on the Main Sequence.

Stellar Interiors - Hydrostatic Equilibrium and Ignition on the Main Sequence http://apod.nasa.gov/apod/astropix.html Outline of today s lecture Hydrostatic equilibrium: balancing gravity and pressure

### Convection causes granules. Photosphere isn t actually smooth! Granules Up-Close: like boiling water. Corona or of the Sun. Chromosphere: sphere of

Overview Properties of the Sun Sun s outer layers Photosphere Chromosphere Corona Solar Activity Sunspots & the sunspot cycle Flares, prominences, CMEs, aurora Sun s Interior The Sun as an energy source

### Reading Clicker Q 2/7/17. Topics for Today and Thur. ASTR 1040: Stars & Galaxies

ASTR 1040: Stars & Galaxies Solar granulation Prof. Juri Toomre TAs: Piyush Agrawal, Connor Bice Lecture 7 Tues 7 Feb 2017 zeus.colorado.edu/astr1040-toomre Topics for Today and Thur Consider Sun s energy

### Astronomy 404 October 9, 2013

Nuclear reaction rate: Astronomy 404 October 9, 2013 from the tunneling increases with increasing E from the velocity distrib. decreases with increasing E The Gamow peak occurs at energy Energy generation

### Solar Interior. Sources of energy for Sun Nuclear fusion Solar neutrino problem Helioseismology

Solar Interior Sources of energy for Sun Nuclear fusion Solar neutrino problem Helioseismology Solar Atmosphere Solar interior Solar facts Luminosity: 3.8x10 26 J/s Mass: 2.0x10 30 kg Composition: 73%

### The Sun. The Sun. Bhishek Manek UM-DAE Centre for Excellence in Basic Sciences. May 7, 2016

The Sun Bhishek Manek UM-DAE Centre for Excellence in Basic Sciences May 7, 2016 Outline 1 Motivation 2 Resume of the Sun 3 Structure of the Sun - Solar Interior and Atmosphere 4 Standard Solar Model -

### UNIVERSITY OF SOUTHAMPTON

UNIVERSITY OF SOUTHAMPTON PHYS3010W1 SEMESTER 2 EXAMINATION 2014-2015 STELLAR EVOLUTION: MODEL ANSWERS Duration: 120 MINS (2 hours) This paper contains 8 questions. Answer all questions in Section A and

### 10/18/ A Closer Look at the Sun. Chapter 11: Our Star. Why does the Sun shine? Lecture Outline

10/18/17 Lecture Outline 11.1 A Closer Look at the Sun Chapter 11: Our Star Our goals for learning: Why does the Sun shine? What is the Sun's structure? Why does the Sun shine? Is it on FIRE? Is it on

### Astronomy 1504 Section 002 Astronomy 1514 Section 10 Midterm 2, Version 1 October 19, 2012

Astronomy 1504 Section 002 Astronomy 1514 Section 10 Midterm 2, Version 1 October 19, 2012 Choose the answer that best completes the question. Read each problem carefully and read through all the answers.

### The Sun. October 21, ) H-R diagram 2) Solar Structure 3) Nuclear Fusion 4) Solar Neutrinos 5) Solar Wind/Sunspots

The Sun October 21, 2002 1) H-R diagram 2) Solar Structure 3) Nuclear Fusion 4) Solar Neutrinos 5) Solar Wind/Sunspots Review Blackbody radiation Measuring stars distance luminosity brightness and distance

### Hydrogen Lines. What can we learn from light? Spectral Classification. Visible Hydrogen Spectrum Lines: Series. Actual Spectrum from SDSS

What can we learn from light? Hydrogen Lines Temperature Energy Chemical Composition Speed towards or away from us All from the! Lower E, Lower f, λ Visible! Higher E, Higher f, λ Visible Hydrogen Spectrum

### Today The Sun. Events

Today The Sun Events Last class! Homework due now - will count best 5 of 6 Final exam Dec. 20 @ 12:00 noon here Review this Course! www.case.edu/utech/course-evaluations/ The Sun the main show in the solar

### The Sun Closest star to Earth - only star that we can see details on surface - easily studied Assumption: The Sun is a typical star

The Sun Closest star to Earth - only star that we can see details on surface - easily studied Assumption: The Sun is a typical star Why is the Sun hot and bright? Surface Temperature of the Sun: T =

### Chapter 14 Our Star Pearson Education, Inc.

Chapter 14 Our Star Basic Types of Energy Kinetic (motion) Radiative (light) Potential (stored) Energy can change type, but cannot be created or destroyed. Thermal Energy: the collective kinetic energy

### Weight of upper layers compresses lower layers

Weight of upper layers compresses lower layers Gravitational equilibrium: Energy provided by fusion maintains the pressure Gravitational contraction: Provided energy that heated core as Sun was forming

### The General Properties of the Sun

Notes: The General Properties of the Sun The sun is an average star with average brightness. It only looks bright because it s so close. It contains 99% of the mass of the solar system. It is made of entirely

### A100 Exploring the Universe: How Stars Work. Martin D. Weinberg UMass Astronomy

A100 Exploring the Universe: How Stars Work Martin D. Weinberg UMass Astronomy weinberg@astro.umass.edu October 11, 2012 Read: Chaps 14, 15 10/11/12 slide 1 Exam scores posted in Mastering Exam keys posted

### Astr 1050 Mon. March 30, 2015 This week s Topics

Astr 1050 Mon. March 30, 2015 This week s Topics Chapter 14: The Sun, Our Star Structure of the Sun Physical Properties & Stability Photosphere Opacity Spectral Line Formation Temperature Profile The Chromosphere

### MAJOR NUCLEAR BURNING STAGES

MAJOR NUCLEAR BURNING STAGES The Coulomb barrier is higher for heavier nuclei with high charge: The first reactions to occur are those involving light nuclei -- Starting from hydrogen burning, helium burning

### 10/17/ A Closer Look at the Sun. Chapter 11: Our Star. Why does the Sun shine? Lecture Outline

Lecture Outline 11.1 A Closer Look at the Sun Chapter 11: Our Star Our goals for learning: Why does the Sun shine? What is the Sun's structure? Why does the Sun shine? Is it on FIRE? Is it on FIRE? Chemical

### Our sole source of light and heat in the solar system. A very common star: a glowing g ball of gas held together by its own gravity and powered

The Sun Visible Image of the Sun Our sole source of light and heat in the solar system A very common star: a glowing g ball of gas held together by its own gravity and powered by nuclear fusion at its

### PHY-105: Nuclear Reactions in Stars (continued)

PHY-105: Nuclear Reactions in Stars (continued) Recall from last lecture that the nuclear energy generation rate for the PP reactions (that main reaction chains that convert hyogen to helium in stars similar

### The interior of the Sun. Space Physics - Project by Christopher Keil. October 17, Supervisor: Prof. Kjell Rnnemark

The interior of the Sun Space Physics - Project by Christopher Keil October 17, 2006 Supervisor: Prof. Kjell Rnnemark Umeå University Institute of Physics Contents 1 Introduction 2 2 The Structure of the

### Chapter 10 Our Star. X-ray. visible

Chapter 10 Our Star X-ray visible Radius: 6.9 10 8 m (109 times Earth) Mass: 2 10 30 kg (300,000 Earths) Luminosity: 3.8 10 26 watts (more than our entire world uses in 1 year!) Why does the Sun shine?

### Lec 7: Classification of Stars, the Sun. What prevents stars from collapsing under the weight of their own gravity? Text

1 Astr 102 Lec 7: Classification of Stars, the Sun What prevents stars from collapsing under the weight of their own gravity? Text Why is the center of the Sun hot? What is the source of the Sun s energy?

### Chapter 9 The Sun. Nuclear fusion: Combining of light nuclei into heavier ones Example: In the Sun is conversion of H into He

Our sole source of light and heat in the solar system A common star: a glowing ball of plasma held together by its own gravity and powered by nuclear fusion at its center. Nuclear fusion: Combining of

### The Sun. How are these quantities measured? Properties of the Sun. Chapter 14

The Sun Chapter 14 The Role of the Sun in the Solar System > 99.9% of the mass Its mass is responsible for the orderly orbits of the planets Its heat is responsible for warming the planets It is the source

### From Last Time: We can more generally write the number densities of H, He and metals.

From Last Time: We can more generally write the number densities of H, He and metals. n H = Xρ m H,n He = Y ρ 4m H, n A = Z Aρ Am H, How many particles results from the complete ionization of hydrogen?

### Stellar Interiors Nuclear Energy ASTR 2110 Sarazin. Fusion the Key to the Stars

Stellar Interiors Nuclear Energy ASTR 2110 Sarazin Fusion the Key to the Stars Energy Source for Stars For Sun, need total energy E = L t Sun = L x (10 10 years) ~ 10 51 erg N atoms = / m p ~ 10 57 atoms

### Stars. The size of the Sun

Stars Huge spheres of gas floating in space Composed primarily of H, He. Produce their own energy. Our Galaxy: 10 11 (100 billion) stars. The Sun: a typical star Stars range from ~ 0.1 to ~ 20 M M = solar

### A100 Exploring the Universe: How Stars Work. Martin D. Weinberg UMass Astronomy

A100 Exploring the Universe: How Stars Work Martin D. Weinberg UMass Astronomy astron100-mdw@courses.umass.edu October 07, 2014 Read: Chaps 14, 15 10/07/12 slide 1 Exam scores posted in Mastering Questions

### The Sun is the nearest star to Earth, and provides the energy that makes life possible.

1 Chapter 8: The Sun The Sun is the nearest star to Earth, and provides the energy that makes life possible. PRIMARY SOURCE OF INFORMATION about the nature of the Universe NEVER look at the Sun directly!!

### The Stars. Chapter 14

The Stars Chapter 14 Great Idea: The Sun and other stars use nuclear fusion reactions to convert mass into energy. Eventually, when a star s nuclear fuel is depleted, the star must burn out. Chapter Outline

### The Sun. Chapter 12. Properties of the Sun. Properties of the Sun. The Structure of the Sun. Properties of the Sun.

Chapter 12 The Sun, Our Star 1 With a radius 100 and a mass of 300,000 that of Earth, the Sun must expend a large amount of energy to withstand its own gravitational desire to collapse To understand this

### Astrophysical Nucleosynthesis

R. D. Gehrz ASTRO 2001, Fall Semester 2018 1 RDG The Chemical Evolution of the Universe 2RDG 1 The Stellar Evolution Cycle 3 RDG a v a v X X V = v a + v X 4 RDG reaction rate r n n s cm ax a X r r ( E)

### Lecture 12: Making the Sun Shine Readings: Sections 18-1, 18-4 and Box 18-1

Lecture 12: Making the Sun Shine Readings: Sections 18-1, 18-4 and Box 18-1 Key Ideas Stars shine because they are hot need an internal energy source to stay hot Kelvin-Helmholtz Mechanism Energy from

### Name: Date: 2. The temperature of the Sun's photosphere is A) close to 1 million K. B) about 10,000 K. C) 5800 K. D) 4300 K.

Name: Date: 1. What is the Sun's photosphere? A) envelope of convective mass motion in the outer interior of the Sun B) lowest layer of the Sun's atmosphere C) middle layer of the Sun's atmosphere D) upper

### 11/19/08. Gravitational equilibrium: The outward push of pressure balances the inward pull of gravity. Weight of upper layers compresses lower layers

Gravitational equilibrium: The outward push of pressure balances the inward pull of gravity Weight of upper layers compresses lower layers Gravitational equilibrium: Energy provided by fusion maintains

### Astronomy Chapter 12 Review

Astronomy Chapter 12 Review Approximately how massive is the Sun as compared to the Earth? A. 100 times B. 300 times C. 3000 times D. 300,000 times E. One million times Approximately how massive is the

### Lecture notes 8: Nuclear reactions in solar/stellar interiors

Lecture notes 8: Nuclear reactions in solar/stellar interiors Atomic Nuclei We will henceforth often write protons 1 1p as 1 1H to underline that hydrogen, deuterium and tritium are chemically similar.

### Our Star: The Sun. Layers that make up the Sun. Understand the Solar cycle. Understand the process by which energy is generated by the Sun.

Goals: Our Star: The Sun Layers that make up the Sun. Understand the Solar cycle. Understand the process by which energy is generated by the Sun. Components of the Sun Solar Interior: Core: where energy

### Exam #2 Review Sheet. Part #1 Clicker Questions

Exam #2 Review Sheet Part #1 Clicker Questions 1) The energy of a photon emitted by thermonuclear processes in the core of the Sun takes thousands or even millions of years to emerge from the surface because

### Radiation Zone. AST 100 General Astronomy: Stars & Galaxies. 5. What s inside the Sun? From the Center Outwards. Meanderings of outbound photons

AST 100 General Astronomy: Stars & Galaxies 5. What s inside the Sun? From the Center Outwards Core: Hydrogen ANNOUNCEMENTS Midterm I on Tue, Sept. 29 it will cover class material up to today (included)

### Some Good News. Announcements. Lecture 10 The Sun. How does the Sun shine? The Sun s Energy Source

Announcements Homework due today. Put your homework in the box NOW. Please STAPLE them if you have not done yet. Quiz#3 on Tuesday (Oct 5) Announcement at the end of this lecture. If you could not pick

### Limb Darkening: The Inside of the Sun: What keeps the Sun shining? What keeps the Sun from collapsing? Gravity versus Pressure. Mechanical Structure

Reading: Chapter 16 (next week: Chapter 17) Exam 1: This Thursday, February 8 - bring a #2 pencil! ESSAY, Review Sheet and Practice Exam Posted Astro 150 Spring 2018: Lecture 9 page 1 Last time: Our Sun

### Hydrogen Burning in More Massive Stars and The Sun.

Hydrogen Burning in More Massive Stars and The Sun http://apod.nasa.gov/apod/astropix.html 2 min For temperatures above 18 million K, the CNO cycle dominates energy production 10 min CNO 14 N CNO CYCLE

### Physics 556 Stellar Astrophysics Prof. James Buckley. Lecture 9 Energy Production and Scaling Laws

Physics 556 Stellar Astrophysics Prof. James Buckley Lecture 9 Energy Production and Scaling Laws Equations of Stellar Structure Hydrostatic Equilibrium : dp Mass Continuity : dm(r) dr (r) dr =4πr 2 ρ(r)

### 5. Energy Production and Transport

5. Energy Production and Transport 5.1 Energy Release from Nuclear Reactions As mentioned when we looked at energy generation, it is now known that most of the energy radiated by stars must be released

### Star Formation and Protostars

Stellar Objects: Star Formation and Protostars 1 Star Formation and Protostars 1 Preliminaries Objects on the way to become stars, but extract energy primarily from gravitational contraction are called

### Summer 2013 Astronomy - Test 3 Test form A. Name

Summer 2013 Astronomy - Test 3 Test form A Name Do not forget to write your name and fill in the bubbles with your student number, and fill in test form A on the answer sheet. Write your name above as

### Astronomy. Our Star, The Sun

Astronomy A. Dayle Hancock adhancock@wm.edu Small 239 Office hours: MTWR 10-11am Our Star, The Sun The source of the Sun's heat and light Models of the Sun's interior The Sun's vibrations Probing the energy

### LIFE CYCLE OF A STAR

LIFE CYCLE OF A STAR First stage = Protostar PROTOSTAR Cloud of gas and dust many light-years across Gravity tries to pull the materials together Eventually, at the center of the ball of dust and gas,

### Explain how the sun converts matter into energy in its core. Describe the three layers of the sun s atmosphere.

Chapter 29 and 30 Explain how the sun converts matter into energy in its core. Describe the three layers of the sun s atmosphere. Explain how sunspots are related to powerful magnetic fields on the sun.

### 9.1 Introduction. 9.2 Static Models STELLAR MODELS

M. Pettini: Structure and Evolution of Stars Lecture 9 STELLAR MODELS 9.1 Introduction Stars are complex physical systems, but not too complex to be modelled numerically and, with some simplifying assumptions,

### Mar 22, INSTRUCTIONS: First ll in your name and social security number (both by printing

ASTRONOMY 0089: EXAM 2 Class Meets M,W,F, 1:00 PM Mar 22, 1996 INSTRUCTIONS: First ll in your name and social security number (both by printing and by darkening the correct circles). Sign your answer sheet

### The Interior Structure of the Sun

The Interior Structure of the Sun Data for one of many model calculations of the Sun center Temperature 1.57 10 7 K Pressure 2.34 10 16 N m -2 Density 1.53 10 5 kg m -3 Hydrogen 0.3397 Helium 0.6405 The

### 2/6/18. Topics for Today and Thur. ASTR 1040: Stars & Galaxies. EUV and Visible Images

2/6/18 ASTR 1040: Stars & Galaxies Topics for Today and Thur Consider Sun s energy source (fusion H--He) Solar granulation Prof. Juri Toomre TAs: Peri Johnson, Ryan Horton Lecture 7 Tues 6 Feb 2018 What

### AST1100 Lecture Notes

AST1100 Lecture Notes 20: Stellar evolution: The giant stage 1 Energy transport in stars and the life time on the main sequence How long does the star remain on the main sequence? It will depend on the

### Pre Main-Sequence Evolution

Stellar Astrophysics: Stellar Evolution Pre Main-Sequence Evolution The free-fall time scale is describing the collapse of the (spherical) cloud to a protostar 1/2 3 π t ff = 32 G ρ With the formation

### Hydrogen Burning in More Massive Stars.

Hydrogen Burning in More Massive Stars http://apod.nasa.gov/apod/astropix.html 2 min For temperatures above 18 million K, the CNO cycle dominates energy production 10 min 14 CNO N CNO CYCLE (Shorthand)

### ASTR-1020: Astronomy II Course Lecture Notes Section VI

ASTR-1020: Astronomy II Course Lecture Notes Section VI Dr. Donald G. Luttermoser East Tennessee State University Edition 4.0 Abstract These class notes are designed for use of the instructor and students

### Atoms and Star Formation

Atoms and Star Formation What are the characteristics of an atom? Atoms have a nucleus of protons and neutrons about which electrons orbit. neutrons protons electrons 0 charge +1 charge 1 charge 1.67 x

### LIFE CYCLE OF A STAR

LIFE CYCLE OF A STAR First stage = Protostar PROTOSTAR Cloud of gas and dust many light-years across Gravity tries to pull the materials together Eventually, at the center of the ball of dust and gas,

### ASTRONOMY 1 EXAM 3 a Name

ASTRONOMY 1 EXAM 3 a Name Identify Terms - Matching (20 @ 1 point each = 20 pts.) Multiple Choice (25 @ 2 points each = 50 pts.) Essays (choose 3 of 4 @ 10 points each = 30 pt 1.Luminosity D 8.White dwarf

### Astronomy Exam 3 - Sun and Stars

Astronomy Exam 3 - Sun and Stars Study online at quizlet.com/_4zgp6 1. `what are the smallest group of stars in the H-R diagram 2. A star has a parallax of 0.05". what is the distance from the earth? white

### The Solar Neutrino Problem. There are 6 major and 2 minor neutrino producing reactions in the sun. The major reactions are

The Solar Neutrino Problem There are 6 major and 2 minor neutrino producing reactions in the sun. The major reactions are 1 H + 1 H 2 H + e + + ν e (PP I) 7 Be + e 7 Li + ν e + γ (PP II) 8 B 8 Be + e +

### Nuclear Binding Energy

Nuclear Energy Nuclei contain Z number of protons and (A - Z) number of neutrons, with A the number of nucleons (mass number) Isotopes have a common Z and different A The masses of the nucleons and the

### The Sun. The Chromosphere of the Sun. The Surface of the Sun

Key Concepts: Lecture 22: The Sun Basic properties of the Sun The outer layers of the Sun: Chromosphere, Corona Sun spots and solar activity: impact on the Earth Nuclear Fusion: the source of the Sun s

### PTYS/ASTR 206. The Sun 3/1/07

The Announcements Reading Assignment Review and finish reading Chapter 18 Optional reading March 2006 Scientific American: article by Gene Parker titled Shielding Space Travelers http://en.wikipedia.org/wiki/solar_variability

### 14.1 A Closer Look at the Sun

14.1 A Closer Look at the Sun Our goals for learning: Why does the Sun shine? What is the Sun's structure? Why does the Sun shine? Is it on FIRE? Is it on FIRE? NO! Chemical energy content Luminosity ~