# Brought to you in glorious, gaseous fusion-surround. Intro to Stars Star Lives 1

Size: px
Start display at page:

Download "Brought to you in glorious, gaseous fusion-surround. Intro to Stars Star Lives 1"

Transcription

1 Brought to you in glorious, gaseous fusion-surround. Intro to Stars Star Lives 1

2 Stellar Evolution Stars are born when fusion reactions begin. Along the way they evolve, i.e. change. Stars die when fusion reactions end. Lives of stars are much to long for us to observe, so we look at stars in various stages and make inferences about how they evolve. Intro to Stars Star Lives 2

3 Collect data for many human beings as to their height and weight. Zeilik 6/e Intro to Stars Star Lives 3

4 Collect data for one person at different points in his life. The graph shows how a person s height and weight change with time. IF we understand how one person evolves over time, we can infer how many people evolve. Zeilik 6/e Intro to Stars Star Lives 4

5 Collect data for many human beings as to their height and weight. With stars, we ll work in reverse. We ll use the data from many stars to infer how a single star evolves. Zeilik 6/e Intro to Stars Star Lives 5

6 Consider an extended family: infants children teenagers adults elderly Most of the family members will be adults in mid-life because that is the longest period of life. => relative number in each stage reflects the relative length of the stage but! you must assume birth and death happen at a regular rate Intro to Stars Star Lives 6

7 Study the H-R Diagram most stars are on the MS => MS phase is the longest phase of life Main Sequence stars are busy converting H into He in their cores and they do so for the major part of their lives. What is the ONE characteristic that determines how a star evolves? Intro to Stars Star Lives 7

8 Star: huge, hot ball of gas, mostly H, heated by thermonuclear reactions in the core Stable star is in balance (MS star) - pressure outwards equals pressure inwards - gravity is pushing in - pressure from fusion reactions is pushing out Intro to Stars Star Lives 8

9 BALANCE!! Zeilik 6/e Intro to Stars Star Lives 9

10 Model for Stellar Anatomy: a stable star must be in balance a star must keep generating energy to stay in balance rate of energy produced = rate of energy radiated away balance must hold at every layer in the star What would happen if there were a backup, a bottleneck? energy transport must be even from core to surface more opaque the star is the slower the energy transport Intro to Stars Star Lives 10

11 To make a model: produces energy gravity pressure in balance energy has to be transported evenly matter behaves like an ideal gas thermonuclear processes mass, chemical composition temperature, pressure, density => model! Intro to Stars Star Lives 11

12 We use LUMINOSITY and TEMPERATURE to plot where the model star should be on an H-R diagram. What we understand about stars comes from the development of theoretical models. What is one BIG problem with the model? Intro to Stars Star Lives 12

13 Stars Evolve: radius temperature luminosity change in complicated ways => changes in placement on H-R diagram Plotting these changes results in an evolutionary track. Intro to Stars Star Lives 13

14 Surface temp. increases, luminosity stays the same. Luminosity Temperature What happens to the size? Intro to Stars Star Lives 14

15 Luminosity increases, temp. stays the same. Luminosity Temperature What happens to the size? Intro to Stars Star Lives 15

16 Intro to Stars Star Lives 16 Zeilik 6/e

17 What causes stars to evolve? Stars are happily burning H into He p-p reaction 4 H nuclei become 1 He nucleus => energy CNO cycle - produces MORE energy (stars > 1.5 M ) Zeilik 6/e Intro to Stars Star Lives 17

18 Eventually the core becomes almost entirely He p-p reactions stop CNO reactions stop fusion no longer keeps the temp. and pressure high What s next? Intro to Stars Star Lives 18

19 What s the conservation of energy trade-off when that happens? Pressure increases Temperature increases 100 million K => triple alpha process 3 He -> 1 C plus energy Helium burning Intro to Stars Star Lives 19

20 What happens when He runs out? Gravity wins, core collapses Pressure increases Temperature increases 600 million K => carbon burning fusing carbon into heavier elements Depending on the of the star, this cycle repeats until iron (Fe) is formed Intro to Stars Star Lives 20

21 This process is called nucleosynthesis - heavier elements are made out of lighter ones. It continues until iron is made and there the process stops entirely. Intro to Stars Star Lives 21

22 Theoretical Evolution of a 1 M Star Protostar - energy from gravitational collapse formed by contraction of cloud dense core forms, rest of cloud accretes on to it (1-4) Completely convective - bubbling ball of gas, very luminous, larger than it will be as a star, temp. is lower Higher luminosity than it will have as a star, temp. lower, opacity is high (2-3) Luminosity decreases, core heats up, 8 million K fusion reactions begin (3-4) Intro to Stars Star Lives 22

23 Most of energy is from fusion => a STAR! ZERO AGE MAIN SEQUENCE STAR 50 million years to get there Where a star ends up on the ZAMS depends on its. More massive is hotter and more. luminous Less massive is cooler and more. luminous Intro to Stars Star Lives 23

24 Main Sequence phase is about 80% of a star s lifetime. This phase ends when almost all the H in the core has been converted to He. temperature in the core gradually increases greater flow of energy to the surface luminosity increases Intro to Stars Star Lives 24

25 Journey Off the Main Sequence H is used up in the core, fusion reactions in the core stop, but carry on yet in a shell around the core Core contracts (why?) Heats up the shell of burning H Reactions go faster Radius increases, surface temperature increases Star next becomes Intro to Stars Star Lives 25

26 Star moves towards the upper right on the H-R diagram CORE : compressed to an extreme density no longer behaves like a gas degenerate electron gas - pushes outwards with a pressure Balance is re-established New temperature is high enough for a new fusion cycle, He -> C - triple-alpha process Rapid ignition spreads quickly - He flash! (only a few minutes) Intro to Stars Star Lives 26

27 Star adjusts to its new fusion cycle radius decreases luminosity decreases He burning phase once again, stable The End is Near Core is eventually all carbon Fusion stops in the core, continues in the shell Star again expands - a red giant 500 million years 3000 K, 1000 L, 100 R Intro to Stars Star Lives 27

28 Triple-alpha processes varies things happen in bursts (thermal pulses) every few thousand years luminosity varies rapidly heavy elements created in the star are carried outward (superwind), ripping off the envelope, leaving only a hot dense core Expelled material leaves a shell planetary nebula - eventually dissipates Planetary nebula - the funeral wreaths of the stars Intro to Stars Star Lives 28

29 M57 The Ring Nebula Green - Oxygen and Nitrogen Red - Hydrogen APOD In the constellation Lyra (summer sky) Intro to Stars Star Lives 29

30 APOD New view of the Ring Nebula from the Subaru Telescope Intro to Stars Star Lives 30

31 The Helix Nebula NGC 7293 APOD 450 Light Years away in the Constellation Aquarius 41 arcminutes in diameter Intro to Stars Star Lives 31

32 Cometary Knots in The Helix Nebula APOD Nitrogen is represented as red, hydrogen emission as green, and oxygen as blue. Intro to Stars Star Lives 32

33 APOD The Cat s Eye Nebula Intro to Stars Star Lives 33

34 APOD M2-9, a butterfly planetary nebula Intro to Stars Star Lives 34

35 NGC 2440 APOD Intro to Stars Star Lives 35

36 The Eskimo Nebula APOD Intro to Stars Star Lives 36

37 APOD M 27 The Dumbbell Nebula Intro to Stars Star Lives 37

38 APOD PKS Intro to Stars Star Lives 38

39 End of a 1 M Star core is a corpse, no more contration, no more fusion - white dwarf (75,000 years) luminosity is low temperature is high eventually cools to a black dwarf (billions of years) Our Sun will expand to about 1.1 AU Earth s air will be ripped off Earth s mantle will be vaporized We ll all be crispy critters. Intro to Stars Star Lives 39

40 Stars of differing masses have different fates Lower mass than 1M : similar to that of a 1 solar mass star takes much longer 0.74 solar mass star - MS lifetime 20 billion years - longer than the age of the Universe! below 0.08 solar masses - never became hot enough for fusion (Jupiter-like objects, brown dwarfs) Intro to Stars Star Lives 40

41 Evolution of Massive Stars 5-10 M very different from Sun-like stars reach higher temperatures in the core while on the MS, burn H=>He via the CNO cycle MS lifetime is about 400 million years Higher temperature => fuse carbon and even higher elements He core does not become degenerate no He flash Intro to Stars Star Lives 41

42 Even more massive stars 20 M stars such as O stars can possibly develop a degenerate carbon core (about 14 solar masses) carbon ignition - blows apart the star in a catacylsmic event - supernova outer layers blast into space Intro to Stars Star Lives 42

43 Observational Evidence examine stars at various stages with different masses with different compositions clusters of stars : groups held together by their own gravity Intro to Stars Star Lives 43

44 OPEN CLUSTERS (Galactic Clusters) stars in a space a few 10 s of ly across as many as 20,000 in our Milky Way Galaxy distinctive H-R diagram family of stars all formed from the same cloud of gas and dust loosely bound gravitationally Intro to Stars Star Lives 44

45 The Pleiades 400 ly away 100 stars within a diameter ~ 10 ly APOD Distinctive H-R diagram for the cluster lower mass stars on the MS higher mass stars have turned off the MS Intro to Stars Star Lives 45

46 M 11 Wild Duck Cluster 3000 ly distant 150 million years old thousands of stars APOD Intro to Stars Star Lives 46

47 M ly away 20 ly across APOD Intro to Stars Star Lives 47

48 NGC 6791 An enigma! APOD Intro to Stars Star Lives 48

49 The Double Cluster NGC 869 and NGC 884. Also known as "h and chi Persei" APOD Intro to Stars Star Lives 49

50 GLOBULAR CLUSTERS 1,000,000 stars in a space ~ 100 ly in diameter at the center ~ 100 stars / cubic ly family of stars all formed from the same cloud of gas and dust tightly bound gravitationally distinct spherical shape, can see individual stars with a small telescope Distinctive H-R diagram MS turns to a red giant branch upper end of MS has disappeared horizontal branch coming back towards the MS Intro to Stars Star Lives 50

51 M 13 in Hercules over 100,000 stars over 150 light years across over 20,000 light years distant over 12 billion years old. APOD Intro to Stars Star Lives 51

52 M 3 APOD Intro to Stars Star Lives 52

53 47 Tucanae Closeup of its dense stellar center APOD Intro to Stars Star Lives 53

54 M 80 APOD Intro to Stars Star Lives 54

55 Stellar Populations Population I Stars found in Open Clusters bluish white (O, B supergiants) more luminous same chemical composition as the Sun (by mass) younger than Population II stars (i.e. of a newer generation) Population II Stars found in Globular Clusters reddish stars brightest are red giants much less metal in their composition than Pop. I older stars (i.e. of an earlier generation) Intro to Stars Star Lives 55

56 Quick model for origin of the Universe H and He created in the Big Bang with only traces of other elements All heavy elements we see today were made in the stars When a star dies, the heavy elements are blown off into the ISM (interstellar medium) Clouds form in the ISM, including these metals New stars form from these clouds The next generation of stars contains more metals than their predecessors Intro to Stars Star Lives 56

57 We know Pop. II stars formed earlier because they have less heavy elements. Population III star would be the original stars - made ONLY of H and He these have not yet been observed Intro to Stars Star Lives 57

58 Comparing Cluster H-R Diagrams Stars in a cluster are born at essentially the same time. They have differing masses which means?????. More massive stars evolve more rapidly than less massive stars. They become red giants more quickly. As the cluster ages, lower and lower mass stars move off the MS. Intro to Stars Star Lives 58

59 How far down the turn-off point is tells you how old a cluster is: lower down => older Globular cluster stars are, in general, older about 15 billion years old ± 2 billion years OLDEST stars known Open cluster stars are, in general, younger range 100 million years - 5 billion years Intro to Stars Star Lives 59

60 Variable Stars stars that are undergoing dramatic changes in their cores, luminosity varies dramatically, and over short periods of time On the H-R diagram, these lie in strips above the M-S. Vary regularly in the He burning phase. Intro to Stars Star Lives 60

61 RR Lyrae Stars vary in regular cycles of about 12 hours Pop. II stars (which means???) 100 L are about 5000 of them known Cepheid Variable Stars I period of 1-10 days II period of days Variation in luminosity comes from the star expanding and contracting - pulsating - star is unstable Intro to Stars Star Lives 61

62 Hot, Dim Stars core left after a red giant star blows off its outer layers - eventually cools to become a white dwarf Above and to the left of white dwarfs on the H-R diagram - HST measured one at 200,000 K Intro to Stars Star Lives 62

63 Synthesis of Elements To survive a star must fuse lighter elements into heavier ones to generate energy. More massive the star, the heavier the elements it can fuse. (Table 16.3) The waste product of one set of reactions becomes the fuel for the next set. Only the very massive can produce elements heavier than O, Ne, Mg, Na in their cores. There are only a few of these - these are responsible for distributing the heavy metals out into space for future stars to include in their formation. Intro to Stars Star Lives 63

### Heading for death. q q

Hubble Photos Credit: NASA, The Hubble Heritage Team (STScI/AURA) Heading for death. q q q q q q Leaving the main sequence End of the Sunlike star The helium core The Red-Giant Branch Helium Fusion Helium

### PHYS 1401: Descriptive Astronomy Notes: Chapter 12

CHAPTER 12: STELLAR EVOLUTION 12.1: LEAVING THE MAIN SEQUENCE Stars and the Scientific Method You cannot observe a single star from birth to death You can observe a lot of stars in a very short period

### Stars, Galaxies & the Universe Announcements. Stars, Galaxies & the Universe Lecture Outline. HW#7 due Friday by 5 pm! (available Tuesday)

Stars, Galaxies & the Universe Announcements HW#7 due Friday by 5 pm! (available Tuesday) Midterm Grades (points) posted today in ICON Exam #2 next week (Wednesday) Review sheet and study guide posted

### Astro 21 first lecture. stars are born but also helps us study how. Density increases in the center of the star. The core does change from hydrogen to

Astro 21 first lecture The H-R H R Diagram helps us study how stars are born but also helps us study how they die. Stars spend most of their lives as main sequence stars. The core does change from hydrogen

### Chapter 12 Stellar Evolution

Chapter 12 Stellar Evolution Guidepost This chapter is the heart of any discussion of astronomy. Previous chapters showed how astronomers make observations with telescopes and how they analyze their observations

### Astronomy. Stellar Evolution

Astronomy A. Dayle Hancock adhancock@wm.edu Small 239 Office hours: MTWR 10-11am Stellar Evolution Main Sequence star changes during nuclear fusion What happens when the fuel runs out Old stars and second

### Comparing a Supergiant to the Sun

The Lifetime of Stars Once a star has reached the main sequence stage of it life, it derives its energy from the fusion of hydrogen to helium Stars remain on the main sequence for a long time and most

### Stellar Midlife. A. Main Sequence Lifetimes. (1b) Lifetime of Sun. Stellar Evolution Part II. A. Main Sequence Lifetimes. B. Giants and Supergiants

Stellar Evolution Part II 1 Stellar Midlife 2 Stellar Midlife A. Main Sequence Lifetimes B. Giants and Supergiants C. Variables (Cepheids) Dr. Bill Pezzaglia Updated Oct 9, 2006 A. Main Sequence Lifetimes

### TA feedback forms are online!

1 Announcements TA feedback forms are online! find the link at the class website. Please take 5 minutes to tell your TAs your opinion. In case you did not notice, the Final is set for 03/21 from 12:00-3:00

### Chapter 12 Review. 2) About 90% of the star's total life is spent on the main sequence. 2)

Chapter 12 Review TRUE/FALSE. Write 'T' if the statement is true and 'F' if the statement is false. 1) As a main-sequence star, the Sun's hydrogen supply should last about 10 billion years from the zero-age

### Lecture Outlines. Chapter 20. Astronomy Today 8th Edition Chaisson/McMillan Pearson Education, Inc.

Lecture Outlines Chapter 20 Astronomy Today 8th Edition Chaisson/McMillan Chapter 20 Stellar Evolution Units of Chapter 20 20.1 Leaving the Main Sequence 20.2 Evolution of a Sun-Like Star 20.3 The Death

### Life and Death of a Star. Chapters 20 and 21

Life and Death of a Star Chapters 20 and 21 90 % of a stars life Most stars spend most of their lives on the main sequence. A star like the Sun, for example, after spending a few tens of millions of years

### Stellar Astronomy Sample Questions for Exam 4

Stellar Astronomy Sample Questions for Exam 4 Chapter 15 1. Emission nebulas emit light because a) they absorb high energy radiation (mostly UV) from nearby bright hot stars and re-emit it in visible wavelengths.

### Guiding Questions. The Birth of Stars

Guiding Questions The Birth of Stars 1 1. Why do astronomers think that stars evolve (bad use of term this is about the birth, life and death of stars and that is NOT evolution)? 2. What kind of matter

### High Mass Stars. Dr Ken Rice. Discovering Astronomy G

High Mass Stars Dr Ken Rice High mass star formation High mass star formation is controversial! May form in the same way as low-mass stars Gravitational collapse in molecular clouds. May form via competitive

### A Star Becomes a Star

A Star Becomes a Star October 28, 2002 1) Stellar lifetime 2) Red Giant 3) White Dwarf 4) Supernova 5) More massive stars Review Solar winds/sunspots Gases and Dust Molecular clouds Protostars/Birth of

### Beyond the Solar System 2006 Oct 17 Page 1 of 5

I. Stars have color, brightness, mass, temperature and size. II. Distances to stars are measured using stellar parallax a. The further away, the less offset b. Parallax angles are extremely small c. Measured

### Chapter 12 Stellar Evolution

Chapter 12 Stellar Evolution Guidepost Stars form from the interstellar medium and reach stability fusing hydrogen in their cores. This chapter is about the long, stable middle age of stars on the main

### Guiding Questions. Stellar Evolution. Stars Evolve. Interstellar Medium and Nebulae

Guiding Questions Stellar Evolution 1. Why do astronomers think that stars evolve? 2. What kind of matter exists in the spaces between the stars? 3. What steps are involved in forming a star like the Sun?

### HR Diagram, Star Clusters, and Stellar Evolution

Ay 1 Lecture 9 M7 ESO HR Diagram, Star Clusters, and Stellar Evolution 9.1 The HR Diagram Stellar Spectral Types Temperature L T Y The Hertzsprung-Russel (HR) Diagram It is a plot of stellar luminosity

### Astronomy Ch. 20 Stellar Evolution. MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.

Name: Period: Date: Astronomy Ch. 20 Stellar Evolution MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. 1) A star (no matter what its mass) spends

### Astronomy Ch. 20 Stellar Evolution. MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.

Name: Period: Date: Astronomy Ch. 20 Stellar Evolution MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. 1) A star (no matter what its mass) spends

### Protostars evolve into main-sequence stars

Understanding how stars evolve requires both observation and ideas from physics The Lives of Stars Because stars shine by thermonuclear reactions, they have a finite life span That is, they fuse lighter

### Ch. 16 & 17: Stellar Evolution and Death

Ch. 16 & 17: Stellar Evolution and Death Stars have lives: born, evolve, die Mass determines stellar evolution: Really Low Mass (0.08 to 0.4 M sun ) Low Mass: (0.4 to 4 M sun ) Long lives High Mass (4

### Why Do Stars Leave the Main Sequence? Running out of fuel

Star Deaths Why Do Stars Leave the Main Sequence? Running out of fuel Observing Stellar Evolution by studying Globular Cluster HR diagrams Plot stars in globular clusters in Hertzsprung-Russell diagram

### Stars & Galaxies. Chapter 27, Section 1. Composition & Temperature. Chapter 27 Modern Earth Science Characteristics of Stars

Stars & Galaxies Chapter 27 Modern Earth Science Chapter 27, Section 1 27.1 Characteristics of Stars Composition & Temperature Scientists use the following tools to study stars Telescope Observation Spectral

### Stars and their properties: (Chapters 11 and 12)

Stars and their properties: (Chapters 11 and 12) To classify stars we determine the following properties for stars: 1. Distance : Needed to determine how much energy stars produce and radiate away by using

### AST 101 Introduction to Astronomy: Stars & Galaxies

AST 101 Introduction to Astronomy: Stars & Galaxies The H-R Diagram review So far: Stars on Main Sequence (MS) Next: - Pre MS (Star Birth) - Post MS: Giants, Super Giants, White dwarfs Star Birth We start

### 1. What is the primary difference between the evolution of a low-mass star and that of a high-mass star?

FYI: The Lives of Stars E3:R6b 1. Read FYI: The Lives of Stars As you read use the spaces below to write down any information you find especially interesting. Also define the bold terms used in the text.

### Age of M13: 14 billion years. Mass of stars leaving the main-sequence ~0.8 solar masses

Age of M13: 14 billion years. Mass of stars leaving the main-sequence ~0.8 solar masses Helium coreburning stars Giants Subgiants Main Sequence Here is a way to think about it. Outside of star Plenty of

### 3/1/18. Things to do. Topics for Today

ASTR 1040: Stars & Galaxies Spirograph Planetary Nebula Prof. Juri Toomre TAs: Peri Johnson, Ryan Horton Lecture 14 Thur 1 Mar 2018 zeus.colorado.edu/astr1040-toomre Topics for Today Revisit birth of stars

### Low mass stars. Sequence Star Giant. Red. Planetary Nebula. White Dwarf. Interstellar Cloud. White Dwarf. Interstellar Cloud. Planetary Nebula.

Low mass stars Interstellar Cloud Main Sequence Star Red Giant Planetary Nebula White Dwarf Interstellar Cloud Main Sequence Star Red Giant Planetary Nebula White Dwarf Low mass stars Interstellar Cloud

### 20. Stellar Death. Interior of Old Low-Mass AGB Stars

20. Stellar Death Low-mass stars undergo three red-giant stages Dredge-ups bring material to the surface Low -mass stars die gently as planetary nebulae Low -mass stars end up as white dwarfs High-mass

### Chapter 19: The Evolution of Stars

Chapter 19: The Evolution of Stars Why do stars evolve? (change from one state to another) Energy Generation fusion requires fuel, fuel is depleted [fig 19.2] at higher temperatures, other nuclear process

### Stars & Galaxies. Chapter 27 Modern Earth Science

Stars & Galaxies Chapter 27 Modern Earth Science Chapter 27, Section 1 27.1 Characteristics of Stars How do astronomers determine the composition and surface temperature of a star? Composition & Temperature

### Chapter 17: Stellar Evolution

Astr 2310 Thurs. Mar. 30, 2017 Today s Topics Chapter 17: Stellar Evolution Birth of Stars and Pre Main Sequence Evolution Evolution on and off the Main Sequence Solar Mass Stars Massive Stars Low Mass

### Reading and Announcements. Read Chapter 14.1, 14.2 Homework #6 due Tuesday, March 26 Exam #2, Thursday, March 28

Reading and Announcements Read Chapter 14.1, 14.2 Homework #6 due Tuesday, March 26 Exam #2, Thursday, March 28 The life of the Sun The Sun started as a cloud of gas. Gravity caused the cloud to collapse.

### AST 101 Introduction to Astronomy: Stars & Galaxies

AST 101 Introduction to Astronomy: Stars & Galaxies Summary: When a Low-Mass Star runs out of Hydrogen in its Core 1. With fusion no longer occurring in the core, gravity causes core collapse 2. Hydrogen

### Ch. 29 The Stars Stellar Evolution

Ch. 29 The Stars 29.3 Stellar Evolution Basic Structure of Stars Mass effects The more massive a star is, the greater the gravity pressing inward, and the hotter and more dense the star must be inside

### Low-mass Stellar Evolution

Low-mass Stellar Evolution The lives of low-mass stars And the lives of massive stars The Structure of the Sun Let s review: The Sun is held together by? The inward force is balanced by? Thinking about

### Before proceeding to Chapter 20 More on Cluster H-R diagrams: The key to the chronology of our Galaxy Below are two important HR diagrams:

Before proceeding to Chapter 20 More on Cluster H-R diagrams: The key to the chronology of our Galaxy Below are two important HR diagrams: 1. The evolution of a number of stars all formed at the same time

### AST 101 Introduction to Astronomy: Stars & Galaxies

The H-R Diagram review So far: AST 101 Introduction to Astronomy: Stars & Galaxies - Stars on Main Sequence (MS) - Pre MS (Star Birth) Next: - Post MS: Giants, Super Giants, White dwarfs Evolution of Low

### 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,

### Chapter 20 Stellar Evolution Part 2. Secs. 20.4, 20.5

Chapter 20 Stellar Evolution Part 2. Secs. 20.4, 20.5 20.4 Evolution of Stars More Massive than the Sun It can be seen from this H-R diagram that stars more massive than the Sun follow very different paths

### Announcements. L! m 3.5 BRIGHT FAINT. Mass Luminosity Relation: Why? Homework#3 will be handed out at the end of this lecture.

Announcements BRIGHT Homework#3 will be handed out at the end of this lecture. Due October 14 (next Thursday) Review of Mid-term exam will be handed out Tuesday. Mid-term exam will be variants (if not

### Protostars on the HR Diagram. Lifetimes of Stars. Lifetimes of Stars: Example. Pressure-Temperature Thermostat. Hydrostatic Equilibrium

Protostars on the HR Diagram Once a protostar is hot enough to start, it can blow away the surrounding gas Then it is visible: crosses the on the HR diagram The more the cloud, the it will form stars Lifetimes

### Lecture 21 Formation of Stars November 15, 2017

Lecture 21 Formation of Stars November 15, 2017 1 2 Birth of Stars Stars originally condense out of a COLD, interstellar cloud composed of H and He + trace elements. cloud breaks into clumps (gravity)

### The Night Sky. The Universe. The Celestial Sphere. Stars. Chapter 14

The Night Sky The Universe Chapter 14 Homework: All the multiple choice questions in Applying the Concepts and Group A questions in Parallel Exercises. Celestial observation dates to ancient civilizations

### 5) What spectral type of star that is still around formed longest ago? 5) A) F B) A C) M D) K E) O

HW2 Name MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. 1) The polarization of light passing though the dust grains shows that: 1) A) the dust grains

### 10/17/2012. Stellar Evolution. Lecture 14. NGC 7635: The Bubble Nebula (APOD) Prelim Results. Mean = 75.7 Stdev = 14.7

1 6 11 16 21 26 31 36 41 46 51 56 61 66 71 76 81 86 91 96 10/17/2012 Stellar Evolution Lecture 14 NGC 7635: The Bubble Nebula (APOD) Prelim Results 9 8 7 6 5 4 3 2 1 0 Mean = 75.7 Stdev = 14.7 1 Energy

### Chapters 12 and 13 Review: The Life Cycle and Death of Stars. How are stars born, and how do they die? 4/1/2009 Habbal Astro Lecture 27 1

Chapters 12 and 13 Review: The Life Cycle and Death of Stars How are stars born, and how do they die? 4/1/2009 Habbal Astro 110-01 Lecture 27 1 Stars are born in molecular clouds Clouds are very cold:

### Review: HR Diagram. Label A, B, C respectively

Stellar Evolution Review: HR Diagram Label A, B, C respectively A C B a) A: White dwarfs, B: Giants, C: Main sequence b) A: Main sequence, B: Giants, C: White dwarfs c) A: Main sequence, B: White Dwarfs,

### Lifespan on the main sequence. Lecture 9: Post-main sequence evolution of stars. Evolution on the main sequence. Evolution after the main sequence

Lecture 9: Post-main sequence evolution of stars Lifetime on the main sequence Shell burning and the red giant phase Helium burning - the horizontal branch and the asymptotic giant branch The death of

### Beyond Our Solar System Chapter 24

Beyond Our Solar System Chapter 24 PROPERTIES OF STARS Distance Measuring a star's distance can be very difficult Stellar parallax Used for measuring distance to a star Apparent shift in a star's position

### Chapter 12: The Lives of Stars. How do we know it s there? Three Kinds of Nebulae 11/7/11. 1) Emission Nebulae 2) Reflection Nebulae 3) Dark Nebulae

11/7/11 Chapter 12: The Lives of Stars Space is Not Empty The Constellation Orion The Orion Nebula This material between the stars is called the Interstellar Medium It is very diffuse and thin. In fact

### ASTR-101 4/4/2018 Stellar Evolution: Part II Lecture 19

ASTR-101 4/4/2018 Stellar Evolution: Part II Lecture 19 WHEN S THE NEXT TEST?!?!?!? If anyone is following the syllabus, you know that it says there is a test today. The test will be on April 11 th (a

### Chapter 17 Lecture. The Cosmic Perspective Seventh Edition. Star Stuff Pearson Education, Inc.

Chapter 17 Lecture The Cosmic Perspective Seventh Edition Star Stuff Star Stuff 17.1 Lives in the Balance Our goals for learning: How does a star's mass affect nuclear fusion? How does a star's mass affect

### Stars IV Stellar Evolution

Stars IV Stellar Evolution Attendance Quiz Are you here today? Here! (a) yes (b) no (c) my views are evolving on the subject Today s Topics Stellar Evolution An alien visits Earth for a day A star s mass

### Birth & Death of Stars

Birth & Death of Stars Objectives How are stars formed How do they die How do we measure this The Interstellar Medium (ISM) Vast clouds of gas & dust lie between stars Diffuse hydrogen clouds: dozens of

### Chapter 14. Stellar Evolution I. The exact sequence of evolutionary stages also depends on the mass of a star.

Chapter 14 Stellar Evolution I I. Introduction Stars evolve in the sense that they pass through different stages of a stellar life cycle that is measured in billions of years. The longer the amount of

### The Formation of Stars

The Formation of Stars A World of Dust The space between the stars is not completely empty, but filled with very dilute gas and dust, producing some of the most beautiful objects in the sky. We are interested

### 17.1 Lives in the Balance. Our goals for learning: How does a star's mass affect nuclear fusion?

Stellar Evolution 17.1 Lives in the Balance Our goals for learning: How does a star's mass affect nuclear fusion? How does a star's mass affect nuclear fusion? Stellar Mass and Fusion The mass of a main-sequence

### The Life and Death of Stars

The Life and Death of Stars What is a Star? A star is a sphere of plasma gas that fuses atomic nuclei in its core and so emits light The name star can also be tagged onto a body that is somewhere on the

### Earth Science, 13e Tarbuck & Lutgens

Earth Science, 13e Tarbuck & Lutgens Beyond Our Solar System Earth Science, 13e Chapter 24 Stanley C. Hatfield Southwestern Illinois College Properties of stars Distance Distances to the stars are very

### Stellar Evolution Notes

Name: Block: Stellar Evolution Notes Stars mature, grow old and die. The more massive a star is, the shorter its life will be. Our Sun will live about 10 billion years. It is already 5 billion years old,

### Page 386 SUMMARY. d TABLE 14.2 EVOLUTION OF LOW MASS AND HIGH MASS STARS Low Mass Star (Mass Less Than 8 M ) High Mass Star (Mass More Than 8 M )

Page 386 SUMMARY A star forms from interstellar gas drawn together by gravity, which compresses and heats the gas to form a protostar. Further heating causes the core of the protostar to fuse hydrogen

### Outline - March 18, H-R Diagram Review. Protostar to Main Sequence Star. Midterm Exam #2 Tuesday, March 23

Midterm Exam #2 Tuesday, March 23 Outline - March 18, 2010 Closed book Will cover Lecture 8 (Special Relativity) through Lecture 14 (Star Formation) only If a topic is in the book, but was not covered

### 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,

### The physics of stars. A star begins simply as a roughly spherical ball of (mostly) hydrogen gas, responding only to gravity and it s own pressure.

Lecture 4 Stars The physics of stars A star begins simply as a roughly spherical ball of (mostly) hydrogen gas, responding only to gravity and it s own pressure. X-ray ultraviolet infrared radio To understand

### The Evolution of Low Mass Stars

The Evolution of Low Mass Stars Key Ideas: Low Mass = M < 4 M sun Stages of Evolution of a Low Mass star: Main Sequence star star star Asymptotic Giant Branch star Planetary Nebula phase White Dwarf star

### Late Stages of Stellar Evolution. Late Stages of Stellar Evolution

Late Stages of Stellar Evolution The star enters the Asymptotic Giant Branch with an active helium shell burning and an almost dormant hydrogen shell Again the stars size and luminosity increase, leading

### 1 The Life Cycle of a Star

CHAPTER 1 The Life Cycle of a Star Describe the life cycle of various size stars. Rings of glowing gas encircling Supernova 1987A, about 179,000 light-years away in the Large Magellanic Cloud, one of the

### Stellar Evolution and the HertzsprungRussell Diagram 7/14/09. Astronomy 101

Stellar Evolution and the HertzsprungRussell Diagram 7/14/09 Astronomy 101 Astronomy Picture of the Day Astronomy 101 Outline for Today Astronomy Picture of the Day News Articles Business Return Lab 5

### The dying sun/ creation of elements

The dying sun/ creation of elements Homework 6 is due Thurs, 2 April at 6:00am OBAFGKM extra credit Angel: Lessons>Extra Credit Due 11:55pm, 31 March Final exam (new, later time) 6 May, 3:00-5:00, BPS

### Astronomy 122 Midterm

Astronomy 122 Midterm This Class (Lecture 15): Stellar Evolution: The Main Sequence Next Class: Stellar Evolution: Post-Main Sequence Midterm on Thursday! Last week for Nightlabs 1 hour exam in this classroom

### Recall what you know about the Big Bang.

What is this? Recall what you know about the Big Bang. Most of the normal matter in the universe is made of what elements? Where do we find most of this normal matter? Interstellar medium (ISM) The universe

### 10/29/2009. The Lives And Deaths of Stars. My Office Hours: Tuesday 3:30 PM - 4:30 PM 206 Keen Building. Stellar Evolution

of s Like s of Other Stellar The Lives And Deaths of s a Sun-like s More 10/29/2009 My Office Hours: Tuesday 3:30 PM - 4:30 PM 206 Keen Building Test 2: 11/05/2009 of s Like s of Other a Sun-like s More

### 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

### Phys 100 Astronomy (Dr. Ilias Fernini) Review Questions for Chapter 9

Phys 0 Astronomy (Dr. Ilias Fernini) Review Questions for Chapter 9 MULTIPLE CHOICE 1. We know that giant stars are larger in diameter than the sun because * a. they are more luminous but have about the

### The Later Evolution of Low Mass Stars (< 8 solar masses)

The sun - past and future The Later Evolution of Low Mass Stars (< 8 solar masses) During 10 billion years the suns luminosity changes only by about a factor of two. After that though, changes become rapid

### Chapter 11 Review. 1) Light from distant stars that must pass through dust arrives bluer than when it left its star. 1)

Chapter 11 Review TRUE/FALSE. Write 'T' if the statement is true and 'F' if the statement is false. 1) Light from distant stars that must pass through dust arrives bluer than when it left its star. 1)

### 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.

### Stellar Evolution Stars spend most of their lives on the main sequence. Evidence: 90% of observable stars are main-sequence stars.

Stellar Evolution Stars spend most of their lives on the main sequence. Evidence: 90% of observable stars are main-sequence stars. Stellar evolution during the main-sequence life-time, and during the post-main-sequence

### Exam 2. Topics for Today s Class 4/16/2018. Announcements for Labs. Chapter 12. Stellar Evolution. Guidepost

Announcements for Labs. Phys1403 Stars and Galaxies Instructor: Dr. Goderya Lab 6 Measuring magnitude of stars as a function of time, now Due on Monday April 23 rd During class time Lab 13 Last Lab of

### The Life of Our Sun The Life of Our Sun

The Life of a Star Chapter 14 Stellar Evolution 1 2 Mass Is the Key Stars require millions to billions of years to evolve a time that is incredibly slow by human standards A star s evolution can be studied

### Stellar Evolution: Outline

Stellar Evolution: Outline Interstellar Medium (dust) Hydrogen and Helium Small amounts of Carbon Dioxide (makes it easier to detect) Massive amounts of material between 100,000 and 10,000,000 solar masses

### What is a star? A body of gases that gives off tremendous amounts of energy in the form of light & heat. What star is closest to the earth?

Stars What is a star? A body of gases that gives off tremendous amounts of energy in the form of light & heat. What star is closest to the earth? Answer: The SUN It s about 150,000,000 km from earth =

### Astronomy 104: Second Exam

Astronomy 104: Second Exam Stephen Lepp October 29, 2014 Each question is worth 2 points. Write your name on this exam and on the scantron. Short Answer A The Sun is powered by converting hydrogen to what?

### Lecture 24. Reprise: Evolution Timescale

Lecture 24 Life as a Low Mass Giant Dating the Stars Shell vs Core Fusion Helium Fusion Planetary Nebulae Mar 22, 2006 Astro 100 Lecture 24 1 Reprise: Evolution Timescale To estimate the duration of any

### Stellar Evolution. Eta Carinae

Stellar Evolution Eta Carinae Evolution of Main Sequence Stars solar mass star: from: Markus Bottcher lecture notes, Ohio University Evolution off the Main Sequence: Expansion into a Red Giant Inner core

### Stars: Their Life and Afterlife

The 68 th Compton Lecture Series Stars: Their Life and Afterlife Lecture 3: The Life and Times of Low Mass Stars Brian Humensky, lecturer http://kicp.uchicago.edu/~humensky/comptonlectures.htm October

### Lecture 8: Stellar evolution II: Massive stars

Lecture 8: Stellar evolution II: Massive stars Senior Astrophysics 2018-03-27 Senior Astrophysics Lecture 8: Stellar evolution II: Massive stars 2018-03-27 1 / 29 Outline 1 Stellar models 2 Convection

### Things to do 3/6/14. Topics for Today & Tues. Clicker review red giants. 2: Subgiant to Red Giant (first visit)

ASTR 1040: Stars & Galaxies Prof. Juri Toomre TA: Ryan Orvedahl Lecture 16 Thur 6 Mar 2014 zeus.colorado.edu/astr1040-toomre Blinking Eye Nebula Topics for Today & Tues Briefly revisit: planetary nebulae

### Introductory Astrophysics A113. Death of Stars. Relation between the mass of a star and its death White dwarfs and supernovae Enrichment of the ISM

Goals: Death of Stars Relation between the mass of a star and its death White dwarfs and supernovae Enrichment of the ISM Low Mass Stars (M

### 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

### Stars and Galaxies 1

Stars and Galaxies 1 Characteristics of Stars 2 Star - body of gases that gives off great amounts of radiant energy as light and heat 3 Most stars look white but are actually different colors Antares -

### NSCI 314 LIFE IN THE COSMOS

NSCI 314 LIFE IN THE COSMOS 2 BASIC ASTRONOMY, AND STARS AND THEIR EVOLUTION Dr. Karen Kolehmainen Department of Physics CSUSB COURSE WEBPAGE: http://physics.csusb.edu/~karen MOTIONS IN THE SOLAR SYSTEM

### Daily Science 03/30/2017

Daily Science 03/30/2017 The atmospheres of different planets contain different gases. Which planet is most likely Earth? a. planet 1 b. planet 2 c. planet 3 d. planet 4 KeslerScience.com Can you name