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 )

Size: px
Start display at page:

Download "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 )"

Transcription

1 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 into helium. The energy released keeps the core hot and thereby maintains an outward pressure that stops the protostar's collapse and changes it into a main sequence star. When the hydrogen is exhausted in a star's core, the core shrinks and heats, making the star swell into a red giant. A low mass star such as the Sun continues to burn hydrogen in a shell during its first red giant stage but eventually compresses the helium in its core enough to ignite the gas in a helium flash. The energy released expands the core, and the outer layers shrink, turning the star into a yellow giant. As the star burns helium, its core again shrinks, and it once more becomes a red giant. It is so luminous now that its radiation drives off its outer layers to form a planetary nebula shell. The core remains as a small, dense star: a white dwarf. Because of the tremendous heating from gravitational compression of their cores, high mass stars more easily ignite fuels heavier than hydrogen and undergo less dramatic changes initially than low mass stars do. They build in their cores layers of heavy elements: carbon, neon, silicon, and, eventually, iron. The iron core cannot burn and will collapse, triggering a supernova explosion. The heavy elements produced during the star's life and in the supernova that destroys it are blasted into space, enriching the interstellar medium. The lifetime of a star is dependent on its mass. High mass stars burn their fuel quickly to supply the energy they need to support their great weight. These stars are blue because they are so hot. Thus, blue stars burn out quickly and must be young. Both high and low mass stars pass through a stage late in their lives when they pulsate as yellow giants. Low mass stars become RR Lyrae variables, whereas high mass stars become Cepheids. Table 14.2 summarizes these stages. Some stars vary in brightness and are called variable stars. Many of these variables lie in a narrow region of the H R diagram called the instability strip. 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 ) Protostar (gravity supplies energy) Main sequence (hydrogen fuses in core) Core hydrogen is consumed Red giant (hydrogen fuses in shell) Core Protostar (gravity supplies energy) Main sequence (hydrogen fuses in core) Core hydrogen is consumed. Yellow supergiant (helium fuses in core Star pulsates.

2 contracts, heats, and ignites helium (helium fl ash). Yellow giant (star pulsates) Red giant (helium fuses in shell)outer layers ejected to form: Planetary nebula Core cools to become white dwarf. Page 387 QUESTIONS FOR REVIEW 1. (14.1) What processes and forces determine the structure of stars? Red supergiant (heavier elements fuse in a series of shells in the star's core)buildup of iron core and its collapse. Supernova explosion when core collapses; remnant may be a neutron star or black hole. 2. (14.1) Through what stages will the Sun evolve? Through what stages will a high mass star evolve? 3. (14.2) What heats a protostar? How can we observe protostars? Why are they surrounded by dust and gas? 4. (14.2) What is a bipolar flow? 5. (14.2) What is a T Tauri star? 6. (14.2) What is a Bok globule? 7. ( ) What determines when a star becomes a main sequence star? 8. (14.3) How long do stars stay on the main sequence? 9. (14.4) What makes a star move off the main sequence? 10. ( ) Where do main sequence stars end up as they evolve? 11. (14.4) Why is it easier for a high mass star than for a low mass star to burn helium? 12. (14.4) Why do high and low mass stars evolve differently as they become red giants? 13. (14.5) What is a variable star? What is meant by the period of a variable star? 14. (14.5) Where in the H R diagram are variable stars found?

3 15. (14.5) What is meant by a pulsating star? Why do stars pulsate? 16. (14.4/14.6) What happens to a solar mass star when it starts to burn helium in its core? What does it turn into? 17. (14.6) What is a planetary nebula? 18. (14.6) What is one explanation for how a low mass star expels its outer layers to make a planetary nebula? 19. (14.6) What is left when a planetary nebula dissipates? 20. (14.7) What makes a high mass star's core collapse? 21. (14.7) Why do neutrons form in a massive star's iron core? 22. (14.7) What is a supernova explosion? 23. (14.7) What kind of subatomic particles have been observed when a supernova explodes? 24. (14.8) How are clusters of stars used to test theories of stellar evolution? THOUGHT QUESTIONS 1. ( /14.1) Stars of all colors are visible to the naked eye, from Betelgeuse's red to Sirius's white to Spica's blue white. If late in their lives, stars did not evolve into giants but just became dimmer and dimmer, what would you expect for the relative numbers of blue, white, yellow and red stars visible in the night sky? Would any kind of yellow stars be visible to the naked eye? 2. (14.2) Inflate a balloon and carefully measure its size. Put it in the freezer for a few hours. Does it look the same when it is cold? How does this relate to how stars form in cold regions of space? 3. (14.2) Describe how a protostar is believed to form. 4. ( ) Take a plastic bottle and put a little soapy water in it. Run your finger across the mouth to make a soap film. Now, without breaking the film, run hot water over the bottle. What happens to the soap film? How does this relate to what happens to a star when it is heated?

4 5. ( ) Suppose that stars could mix unburned fuel from their outer layers into their cores. Would that alter the way they evolve? Can you suggest some possible differences? 6. (14.6) Hold a clear cylindrical water glass below a bright light so that it casts a shadow on a piece of paper. If you hold the glass at different angles, you can create different shadow patterns. Can you produce shapes similar to the planetary nebula images in figure 14.19? Is there another shape that would create patterns more similar to some images? 7. (14.7) Hold a small rubber ball on top of a basketball, and drop them together toward the floor. What happens to the small ball? Does that help you understand what happens to the outer layers of a supernova as they collapse on the core? 8. (14.7) Thinking about why massive stars start fusing heavy elements, and examining the periodic table in the back of the book, explain why there should be more neon, magnesium, sulfur, argon, and calcium in a supernova remnant than fluorine, sodium, phosphorus, and chlorine. 9. (14.7) Explain why gold and platinum are much scarcer than iron and silicon (found in most rocks), thinking about how massive stars live and die. 10. (14.7/14.8) In some very old, dense star clusters, a few blue stars, known as blue stragglers, are seen. Why are blue stars unexpected in such clusters? If stars that stick together mix their material thoroughly when they collide, how might you explain such blue stars?. PROBLEMS 1. (14.1) Sketch an H R diagram of what you expect the evolutionary paths of a 2 M and a 15 M star to look like. 2. (14.2) The density of a cold interstellar cloud prior to collapsing might be about kg/m 3. How many cubic meters of this cloud would contain enough mass to build the Sun? What is the ratio of this volume to the volume of the Sun? What is the volume of cloud required if written in cubic light years? Page (14.2) The jets from a T Tauri star are measured to have speeds of about 300 km/sec. At this speed, how long would it take the ejected material to travel 2 light years (similar to the jets shown in figure 14.7)? 4. (14.3) Calculate the main sequence lifetime of the Sun by first determining the rate at which it burns hydrogen (refer to chapter 12) and then dividing that rate into its core mass. If your is in

5 seconds, convert to years, given that there are about seconds in a year. 5. (14.4/14.6) Calculate the escape velocity from a red giant's atmosphere (use the formula for escape velocity from chapter 3. Assume that the star's mass is 1 M and its radius is 100 R. How does this compare with the speed at which a planetary nebula shell is ejected? 6. (14.6) Calculate the average density of a red giant star in grams per cubic centimeter. Take the star's mass to be grams and its radius to be centimeters. How does this density compare with that of the air we breathe (about 10 3 gm/cm 3 )? 7. (14.6) How long will it take a planetary nebula shell moving at 20 km/sec to expand to a radius of one fourth of a light year? 8. (14.7) Calculate the Doppler shift of X rays emitted from shocked silicon in a supernova remnant if the ejected material is moving at 5000 km/sec and the X ray line is at nanometers. 9. (14.8) Figure shows the H R diagram of a star cluster. How old is it? (The dashed line is the position of the stars. The solid line is the main sequence.). Figure H R diagram of a star cluster. TEST YOURSELF 1. (14.1) Which of the following sequences correctly describes the evolution of the Sun from young to old?

6 (a) White dwarf, red giant, main sequence, protostar (b) Red giant, main sequence, white dwarf, protostar (c) Protostar, red giant, main sequence, white dwarf (d) Protostar, main sequence, white dwarf, red giant (e) Protostar, main sequence, red giant, white dwarf 2. (14.1) and drive what happens in every phase of a star's life. (a) Gravity, composition (b) Gravity, mass of the star (c) Fusion of hydrogen, gravity (d) Angular momentum, composition (e) Radiation pressure, angular momentum 3. (14.2) All of the following are terms related to star formation except (a) T Tauri stars. (b) Bok globules. (c) interstellar cloud.

7 (d) bipolar outflow. (e) planetary nebula. 4. (14.3) A star whose mass is 5 times larger than the Sun's and whose luminosity is 100 times larger than the Sun's has a main sequence lifetime about (a) 5 times longer than the Sun's. (b) 500 times longer than the Sun's. (c) 5 times shorter than the Sun's. (d) 100 times shorter than the Sun's. (e) 20 times shorter than the Sun's. 5. (14.4) The helium flash occurs in stars with a degenerate core because (a) degenerate gas expands faster than ideal gases. (b) stars with degenerate cores are larger. (c) a degenerate gas can get very hot over a large range very quickly. (d) stars with degenerate cores have much lower densities in the core. 6. (14.5) Variable stars are useful because (choose all that apply)

8 (a) they can be used as standard candles. (b) they provide ways to test stellar structure theories. (c) their luminosity can be determined from the period. (d) many variable stars have large luminosities. 7. (14.6) A planetary nebula is (a) another term for the disk of gas around a young star. (b) the cloud from which protostars form. (c) a shell of gas ejected from a star late in its life. (d) what is left when a white dwarf star explodes as a supernova. (e) the remnants of the explosion created by the collapse of the iron core in a massive star. 8. Page 389 (14.6) As a star like the Sun evolves into a red giant, its core (a) expands and cools. (b) contracts and heats. (c) expands and heats.

9 (d) turns into iron. (e) turns into uranium. 9. ( ) Stars like the Sun probably do not form iron cores during their evolution because (a) all the iron is ejected when they become planetary nebulas. (b) their cores never get hot enough for them to make iron by nucleosynthesis. (c) the iron they make by nucleosynthesis is all fused into uranium. (d) their strong magnetic fields keep their iron in their atmospheres. (e) None of the above. 10. (14.7) A supernova (select all that are correct) (a) creates elements heavier than iron. (b) is the final state of all stars. (c) disperses metals into the interstellar medium. (d) can outshine the rest of a galaxy. (e) can trigger star formation in a nearby cloud.

10 11. (14.8) An H R diagram of a cluster created from data that included the spectral types of the stars could be used to determine (select all that are correct) (a) the age of the cluster. (b) the angular momentum of the stars in the cluster. (c) the gravitational force in the cluster. (d) the distance of the cluster. (e) None of the s are correct. KEY TERMS bipolar flows, 368 degenerate gas, 373 deuterium, 367 helium flash, 374 instability strip, 376 interstellar cloud, 363 main sequence lifetime, 371 nucleosynthesis, 380 period luminosity relation, 376 planetary nebulas, 378 protostar, 366 red giant, 372 shell source, 372 supernova, 381 supernova remnant, 383 triple alpha process, 373

11 T Tauri stars, 368 turnoff point, 385 variable star, 374 Q FIGURE QUESTION ANSWERS WHAT IS THIS? (chapter opening): This is a Hubble Space Telescope image of the Eskimo nebula, so named because it resembles a head surrounded by a parka hood. This planetary nebula is composed of gas that was the outer layers of a star, expelled beginning about 10,000 years ago. FIGURE 14.9: The red glow is caused by hydrogen emission lines. FIGURE 14.17: About 1000 times the Sun's luminosity. FIGURE 14.19: The central star will eventually cool off and become a white dwarf. The nebula will expand, becoming ever larger, and eventually will mingle with the surrounding interstellar gas. PROJECTS Understanding the H R Diagram: The solid line that illustrates the evolutionary path of a star like the Sun in Figure is a bit deceptive. It gives the impression that we are as likely to see stars like the Sun in their protostar phase as in their main sequence phase. A star moves through some phases rapidly and others much more slowly. If instead of a line you put down one point for every 10 million years, you would get a better idea of where you would be likely to see stars like the Sun in the H R diagram. Draw your own version of Figure with a very light line tracing the Sun's path. Now, darker and in a different color, try to place points along the line using the following numbers to estimate how many dots to put down over each section of the line corresponding to each part of the Sun's evolutionary path: protostar phase ~20 million years (Myr); main sequence phase ~10,000 Myr; first red giant phase ~1000 Myr; yellow giant phase ~100 Myr; second red giant phase ~10 Myr; planetary nebula phase 0.01 Myr; white dwarf phase ~3000 Myr. (The star remains a white dwarf beyond this time, but fades from visibility.) Does any part of your graph resemble a solid line?

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

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?

More information

Stellar Evolution Notes

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,

More information

Stellar Astronomy Sample Questions for Exam 4

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.

More information

Guiding Questions. The Birth of Stars

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

More information

Exam # 3 Tue 12/06/2011 Astronomy 100/190Y Exploring the Universe Fall 11 Instructor: Daniela Calzetti

Exam # 3 Tue 12/06/2011 Astronomy 100/190Y Exploring the Universe Fall 11 Instructor: Daniela Calzetti Exam # 3 Tue 12/06/2011 Astronomy 100/190Y Exploring the Universe Fall 11 Instructor: Daniela Calzetti INSTRUCTIONS: Please, use the `bubble sheet and a pencil # 2 to answer the exam questions, by marking

More information

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?

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 =

More information

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

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.

More information

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

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

More information

Lecture 21 Formation of Stars November 15, 2017

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)

More information

Comparing a Supergiant to the Sun

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

More information

18. Stellar Birth. Initiation of Star Formation. The Orion Nebula: A Close-Up View. Interstellar Gas & Dust in Our Galaxy

18. Stellar Birth. Initiation of Star Formation. The Orion Nebula: A Close-Up View. Interstellar Gas & Dust in Our Galaxy 18. Stellar Birth Star observations & theories aid understanding Interstellar gas & dust in our galaxy Protostars form in cold, dark nebulae Protostars evolve into main-sequence stars Protostars both gain

More information

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

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

More information

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

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

More information

Protostars evolve into main-sequence stars

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

More information

Recall what you know about the Big Bang.

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

More information

The Formation of Stars

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

More information

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

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

More information

The Life Cycle of Stars. : Is the current theory of how our Solar System formed.

The Life Cycle of Stars. : Is the current theory of how our Solar System formed. Life Cycle of a Star Video (5 min) http://www.youtube.com/watch?v=pm9cqdlqi0a The Life Cycle of Stars Solar Nebula Theory : Is the current theory of how our Solar System formed. This theory states that

More information

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.

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

More information

The Life of Our Sun The Life of Our Sun

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

More information

Life and Death of a Star 2015

Life and Death of a Star 2015 Life and Death of a Star 2015 Name Date 1. In the main-sequence, the core is slowly shrinking because A. the mass of the star is slowly increasing B. hydrogen fusing to helium makes the core more dense

More information

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

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

More information

Ch. 29 The Stars Stellar Evolution

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

More information

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 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.

More information

Life and Death of a Star. Chapters 20 and 21

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

More information

Prentice Hall EARTH SCIENCE

Prentice Hall EARTH SCIENCE Prentice Hall EARTH SCIENCE Tarbuck Lutgens Chapter 25 Beyond Our Solar System 25.1 Properties of Stars Characteristics of Stars A constellation is an apparent group of stars originally named for mythical

More information

Physics HW Set 3 Spring 2015

Physics HW Set 3 Spring 2015 1) If the Sun were replaced by a one solar mass black hole 1) A) life here would be unchanged. B) we would still orbit it in a period of one year. C) all terrestrial planets would fall in immediately.

More information

Beyond the Solar System 2006 Oct 17 Page 1 of 5

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

More information

The Birth Of Stars. How do stars form from the interstellar medium Where does star formation take place How do we induce star formation

The Birth Of Stars. How do stars form from the interstellar medium Where does star formation take place How do we induce star formation Goals: The Birth Of Stars How do stars form from the interstellar medium Where does star formation take place How do we induce star formation Interstellar Medium Gas and dust between stars is the interstellar

More information

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

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.

More information

Stellar Evolution: Outline

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

More information

the nature of the universe, galaxies, and stars can be determined by observations over time by using telescopes

the nature of the universe, galaxies, and stars can be determined by observations over time by using telescopes the nature of the universe, galaxies, and stars can be determined by observations over time by using telescopes The spectral lines of stars tell us their approximate composition Remember last year in Physics?

More information

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

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,

More information

Chapter 17: Stellar Evolution

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

More information

The Life Cycles of Stars. Modified from Information provided by: Dr. Jim Lochner, NASA/GSFC

The Life Cycles of Stars. Modified from Information provided by: Dr. Jim Lochner, NASA/GSFC The Life Cycles of Stars Modified from Information provided by: Dr. Jim Lochner, NASA/GSFC Twinkle, Twinkle, Little Star... What do you see? How I Wonder What You Are... Stars have: Different Colors -

More information

Star Formation A cloud of gas and dust, called a nebula, begins spinning & heating up. Eventually, it gets hot enough for fusion to take place, and a

Star Formation A cloud of gas and dust, called a nebula, begins spinning & heating up. Eventually, it gets hot enough for fusion to take place, and a Stars Star- large ball of gas held together by gravity that produces tremendous amounts of energy and shines Sun- our closest star Star Formation A cloud of gas and dust, called a nebula, begins spinning

More information

Star formation and Evolution

Star formation and Evolution Star formation and Evolution 1 Star formation and Evolution Stars burn fuel to produce energy and shine so they must evolve and live through a life cycle In the Milky Way we see stars at every stage of

More information

Birth & Death of Stars

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

More information

8/30/2010. Classifying Stars. Classifying Stars. Classifying Stars

8/30/2010. Classifying Stars. Classifying Stars. Classifying Stars Classifying Stars In the early 1900s, Ejnar Hertzsprung and Henry Russell made some important observations. They noticed that, in general, stars with higher temperatures also have brighter absolute magnitudes.

More information

Planetary Nebulae White dwarfs

Planetary Nebulae White dwarfs Life of a Low-Mass Star AST 101 Introduction to Astronomy: Stars & Galaxies Planetary Nebulae White dwarfs REVIEW END STATE: PLANETARY NEBULA + WHITE DWARF WHAS IS A WHITE DWARF? Exposed core of a low-mass

More information

Life Cycle of a Star - Activities

Life Cycle of a Star - Activities Name: Class Period: Life Cycle of a Star - Activities A STAR IS BORN STAGES COMMON TO ALL STARS All stars start as a nebula. A nebula is a large cloud of gas and dust. Gravity can pull some of the gas

More information

Properties of Stars. Characteristics of Stars

Properties of Stars. Characteristics of Stars Properties of Stars Characteristics of Stars A constellation is an apparent group of stars originally named for mythical characters. The sky contains 88 constellations. Star Color and Temperature Color

More information

HR Diagram, Star Clusters, and Stellar Evolution

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

More information

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 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:

More information

PHYS 1401: Descriptive Astronomy Notes: Chapter 12

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

More information

25.2 Stellar Evolution. By studying stars of different ages, astronomers have been able to piece together the evolution of a star.

25.2 Stellar Evolution. By studying stars of different ages, astronomers have been able to piece together the evolution of a star. 25.2 Stellar Evolution By studying stars of different ages, astronomers have been able to piece together the evolution of a star. Star Birth The birthplaces of stars are dark, cool interstellar clouds,

More information

Guiding Questions. The Deaths of Stars. Pathways of Stellar Evolution GOOD TO KNOW. Low-mass stars go through two distinct red-giant stages

Guiding Questions. The Deaths of Stars. Pathways of Stellar Evolution GOOD TO KNOW. Low-mass stars go through two distinct red-giant stages The Deaths of Stars 1 Guiding Questions 1. What kinds of nuclear reactions occur within a star like the Sun as it ages? 2. Where did the carbon atoms in our bodies come from? 3. What is a planetary nebula,

More information

The Deaths of Stars 1

The Deaths of Stars 1 The Deaths of Stars 1 Guiding Questions 1. What kinds of nuclear reactions occur within a star like the Sun as it ages? 2. Where did the carbon atoms in our bodies come from? 3. What is a planetary nebula,

More information

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

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

More information

1 The Life Cycle of a Star

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

More information

Exam #2 Review Sheet. Part #1 Clicker Questions

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

More information

Stellar Evolution: The Deaths of Stars. Guiding Questions. Pathways of Stellar Evolution. Chapter Twenty-Two

Stellar Evolution: The Deaths of Stars. Guiding Questions. Pathways of Stellar Evolution. Chapter Twenty-Two Stellar Evolution: The Deaths of Stars Chapter Twenty-Two Guiding Questions 1. What kinds of nuclear reactions occur within a star like the Sun as it ages? 2. Where did the carbon atoms in our bodies come

More information

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

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

More information

Guiding Questions. The Deaths of Stars. Pathways of Stellar Evolution GOOD TO KNOW. Low-mass stars go through two distinct red-giant stages

Guiding Questions. The Deaths of Stars. Pathways of Stellar Evolution GOOD TO KNOW. Low-mass stars go through two distinct red-giant stages The Deaths of Stars Guiding Questions 1. What kinds of nuclear reactions occur within a star like the Sun as it ages? 2. Where did the carbon atoms in our bodies come from? 3. What is a planetary nebula,

More information

Introduction to Astronomy. Lecture 8: The Death of Stars White Dwarfs, Neutron Stars, and Black Holes

Introduction to Astronomy. Lecture 8: The Death of Stars White Dwarfs, Neutron Stars, and Black Holes Introduction to Astronomy Lecture 8: The Death of Stars White Dwarfs, Neutron Stars, and Black Holes Continued from Last Week Lecture 7 Observing Stars Clusters of stars Some clouds start breaking into

More information

Ch. 16 & 17: Stellar Evolution and Death

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

More information

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

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

More information

A Star Becomes a Star

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

More information

NSCI 314 LIFE IN THE COSMOS

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

More information

Star Formation. Stellar Birth

Star Formation. Stellar Birth Star Formation Lecture 12 Stellar Birth Since stars don t live forever, then they must be born somewhere and at some time in the past. How does this happen? And when stars are born, so are planets! 1 Molecular

More information

Astronomy 104: Second Exam

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?

More information

Astronomy 113. Dr. Joseph E. Pesce, Ph.D. Dr. Joseph E. Pesce, Ph.D.

Astronomy 113. Dr. Joseph E. Pesce, Ph.D. Dr. Joseph E. Pesce, Ph.D. Astronomy 113 Dr. Joseph E. Pesce, Ph.D. Stellar Deaths/Endpoints 13-2 Low Mass Stars ³ Like the Sun (< 2 M ) ² Live about 10 billion years (sun is middle aged) ² Create elements through Carbon, Nitrogen,

More information

Topics for Today s Class

Topics for Today s Class Foundations of Astronomy 13e Seeds Chapter 11 Formation of Stars and Structure of Stars Topics for Today s Class 1. Making Stars from the Interstellar Medium 2. Evidence of Star Formation: The Orion Nebula

More information

Life Cycle of a Star Worksheet

Life Cycle of a Star Worksheet Life Cycle of a Star Worksheet A STAR IS BORN STAGES COMMON TO ALL STARS All stars start as a nebula. A nebula is a large cloud of gas and dust. Gravity can pull some of the gas and dust in a nebula together.

More information

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

Brought to you in glorious, gaseous fusion-surround. Intro to Stars Star Lives 1 Brought to you in glorious, gaseous fusion-surround. Intro to Stars Star Lives 1 Stellar Evolution Stars are born when fusion reactions begin. Along the way they evolve, i.e. change. Stars die when fusion

More information

Stellar Evolution - Chapter 12 and 13. The Lives and Deaths of Stars White dwarfs, neutron stars and black holes

Stellar Evolution - Chapter 12 and 13. The Lives and Deaths of Stars White dwarfs, neutron stars and black holes Stellar Evolution - Chapter 12 and 13 The Lives and Deaths of Stars White dwarfs, neutron stars and black holes During the early stages of a star formation the objects are called a protostars. The internal

More information

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

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

More information

Chapter 12 Stellar Evolution

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

More information

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

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

More information

Physics Homework Set 2 Sp 2015

Physics Homework Set 2 Sp 2015 1) A large gas cloud in the interstellar medium that contains several type O and B stars would appear to us as 1) A) a reflection nebula. B) a dark patch against a bright background. C) a dark nebula.

More information

Chapter 33 The History of a Star. Introduction. Radio telescopes allow us to look into the center of the galaxy. The milky way

Chapter 33 The History of a Star. Introduction. Radio telescopes allow us to look into the center of the galaxy. The milky way Chapter 33 The History of a Star Introduction Did you read chapter 33 before coming to class? A. Yes B. No You can see about 10,000 stars with the naked eye. The milky way Radio telescopes allow us to

More information

Stellar evolution Part I of III Star formation

Stellar evolution Part I of III Star formation Stellar evolution Part I of III Star formation The interstellar medium (ISM) The space between the stars is not completely empty, but filled with very dilute gas and dust, producing some of the most beautiful

More information

Evolution of High Mass Stars

Evolution of High Mass Stars Luminosity (L sun ) Evolution of High Mass Stars High Mass Stars O & B Stars (M > 4 M sun ): Burn Hot Live Fast Die Young Main Sequence Phase: Burn H to He in core Build up a He core, like low-mass stars

More information

Stars & Galaxies. Chapter 27 Modern Earth Science

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

More information

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

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

More information

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

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

More information

Astronomy. Stellar Evolution

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

More information

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

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

More information

Brock University. Test 1, February, 2017 Number of pages: 9 Course: ASTR 1P02 Number of Students: 480 Date of Examination: February 6, 2017

Brock University. Test 1, February, 2017 Number of pages: 9 Course: ASTR 1P02 Number of Students: 480 Date of Examination: February 6, 2017 Brock University Test 1, February, 2017 Number of pages: 9 Course: ASTR 1P02 Number of Students: 480 Date of Examination: February 6, 2017 Number of hours: 50 min Time of Examination: 18:00 18:50 Instructor:

More information

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: 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

More information

Astronomy Ch. 21 Stellar Explosions. MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.

Astronomy Ch. 21 Stellar Explosions. MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. Name: Period: Date: Astronomy Ch. 21 Stellar Explosions MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. 1) A surface explosion on a white dwarf, caused

More information

Earth Science, 13e Tarbuck & Lutgens

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

More information

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

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

More information

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

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

More information

Review Questions for the new topics that will be on the Final Exam

Review Questions for the new topics that will be on the Final Exam Review Questions for the new topics that will be on the Final Exam Be sure to review the lecture-tutorials and the material we covered on the first three exams. How does speed differ from velocity? Give

More information

ASTRONOMY 1 EXAM 3 a Name

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

More information

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. 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

More information

Stars and Galaxies 1

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 -

More information

How Do Stars Appear from Earth?

How Do Stars Appear from Earth? How Do Stars Appear from Earth? Magnitude: the brightness a star appears to have from Earth Apparent Magnitude depends on 2 things: (actual intrinsic brightness) The color of a star is related to its temperature:

More information

Brock University. Test 1, January, 2015 Number of pages: 9 Course: ASTR 1P02 Number of Students: 500 Date of Examination: January 29, 2015

Brock University. Test 1, January, 2015 Number of pages: 9 Course: ASTR 1P02 Number of Students: 500 Date of Examination: January 29, 2015 Brock University Test 1, January, 2015 Number of pages: 9 Course: ASTR 1P02 Number of Students: 500 Date of Examination: January 29, 2015 Number of hours: 50 min Time of Examination: 18:00 15:50 Instructor:

More information

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

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

More information

December 18, What do you know about the life of a star?

December 18, What do you know about the life of a star? December 18, 2013 What do you know about the life of a star? Bellwork December 18, 2014 What determines the life cycle and life time of a star? Scale 4 3 2 1 0 I am a 3 and can apply the stages to the

More information

Chapter 19: The Evolution of Stars

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

More information

*Generally speaking, there are two main life cycles for stars. *The factor which determines the life cycle of the star is its mass.

*Generally speaking, there are two main life cycles for stars. *The factor which determines the life cycle of the star is its mass. Generally speaking, there are two main life cycles for stars. The factor which determines the life cycle of the star is its mass. 1 solar mass = size of our Sun Any star less than about three solar masses

More information

Beyond Our Solar System Chapter 24

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

More information

Heading for death. q q

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

More information

Stars and Galaxies. Evolution of Stars

Stars and Galaxies. Evolution of Stars chapter 13 3 Stars and Galaxies section 3 Evolution of Stars Before You Read What makes one star different from another? Do you think the Sun is the same as other stars? Write your ideas on the lines below.

More information

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 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

More information

Astro 1050 Fri. Apr. 10, 2015

Astro 1050 Fri. Apr. 10, 2015 Astro 1050 Fri. Apr. 10, 2015 Today: Continue Ch. 13: Star Stuff Reading in Bennett: For Monday: Finish Chapter 13 Star Stuff Reminders: Ch. 12 HW now on Mastering Astronomy, due Monday. Ch. 13 will be

More information

Daily Science 03/30/2017

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

More information