Teachers Notes Booklet 5: Stellar Processes and Evolution Page 1 of 16
|
|
- Matthew Mason
- 5 years ago
- Views:
Transcription
1 Teachers Notes Booklet 5: Stellar Processes and Evolution Page 1 of 16
2 The European Space Agency The European Space Agency (ESA) was formed on 31 May It currently has 17 Member States: Austria, Belgium, Denmark, Finland, France, Germany, Greece, Ireland, Italy, Luxembourg, the Netherlands, Norway, Portugal, Spain, Sweden, Switzerland & United Kingdom. The ESA Science Programme currently contains the following active missions: Venus Express an exploration of our sister planet. Rosetta first mission to fly alongside and land on a comet Double Star joint mission with the Chinese to study the effect of the Sun on the Earth s environment SMART-1 Europe s first mission to the Moon, which will test solar-electric propulsion in flight, a key technology for future deep-space missions Mars Express - Europe's first mission to Mars consisting of an orbital platform searching for water and life on the planet INTEGRAL first space observatory to simultaneously observe celestial objects in gamma rays, X-rays and visible light Cluster a four spacecraft mission to investigate interactions between the Sun and the Earth's magnetosphere XMM-Newton an X-ray telescope helping to solve cosmic mysteries Cassini-Huygens a joint ESA/NASA mission to investigate Saturn and its moon Titan, with ESA's Huygens probe SOHO - new views of the Sun's atmosphere and interior Hubble Space Telescope world's most important and successful orbital observatory Ulysses the first spacecraft to investigate the polar regions around the Sun Details on all these missions and others can be found at - Prepared by Anne Brumfitt Content Advisor Chris Lawton Science Editor, Content Advisor, Web Integration & Booklet Design Karen O'Flaherty Science Editor & Content Advisor Jo Turner Content Writer 2005 European Space Agency Teachers Notes Booklet 5: Stellar Processes and Evolution Page 2 of 16
3 Booklet 5 Stellar Processes and Evolution Contents 5.1 Stellar Fusion Nucleosynthesis Evolution Paths on HR Diagram Solar Mass Stars Medium Mass Stars High Mass Stars Other Materials Tables 5.1 Proton-Proton Chain CNO Cycle Dates of Primary Meteor Showers... 8 Figures 5.1 Proton-Proton Chain CNO Cycle Evolutionary Paths Off the Main Sequence... 9 Teachers Notes Booklet 5: Stellar Processes and Evolution Page 3 of 16
4 5.1 Stellar Fusion Stars form out of nebulae giant clouds of gas found in the spiral arms of galaxies. The gas (predominantly hydrogen) can exist in a cloud for many millions of years, but if it is somehow disturbed (by the blast from a nearby supernova, or through intercloud collision for example) the cloud may collapse in on itself. As the density of the core region increases the collapse accelerates due to the everincreasing gravitational attraction. The central region will start to collapse faster than the outer regions and so a cloud of gas shrouds the core. If the cloud is particularly large it may produce multiple stars. This process of cloud collapse signifies the start of star formation. Under continuing collapse, the gas in the cloud begins to warm up and gradually brightens. Eventually the core region reaches a critical temperature such that nuclear reactions can begin and the body evolves from a protostar into a true star. The remaining gas and dust from the original interstellar cloud starts to condense and planets can form. A strong stellar wind, however, drives away some of the matter. Such stars are called as T Tauri stars (from the first star of this type to be observed). Teachers Notes Booklet 5: Stellar Processes and Evolution Page 4 of 16
5 5.2 Nucleosynthesis Nuclear fusion, where nuclei combine to make a nucleus with a larger number of protons and neutrons, occurs in main sequence stars once they reach a critical temperature. As the core temperature rises, due to ongoing core contractions and resulting increase in pressure, the atomic nuclei move faster thereby increasing the probability of two nuclei colliding with each other and fusing into heavier elements. Proton-Proton Chain The simplest reaction that occurs in stars is the conversion of hydrogen into helium - a process known as the proton-proton chain and requires a core temperature of at least 10 million K. In this process six hydrogen atoms are needed to create one helium nucleus of two protons and two neutrons. Process Result Extras 1 proton + proton deuterium positron, neutrino 2 proton + deuterium helium-3 gamma-ray 3 helium-3 + helium-3 helium-4 2 protons Table 5.1: Proton-Proton Chain Reactions In Step 1 two protons come together to form deuterium (a nucleus of one proton and one neutron). This interaction also involves the liberation of a positron (a positively charged electron) and a neutrino. This process occurs times per second in the Sun. In Step 2 the resulting deuterium nucleus combines with a proton to make the rare isotope helium-3 consisting of one neutron and two protons. This reaction also produces a gamma-ray. In Step 3 the helium-3 nucleus becomes a helium-4 nucleus by the addition of a neutron. This step can occur in several ways, but the combination of two helium-3 nuclei is the most common way. Steps 1 and 2 must occur twice before step 3 can occur. Six protons go into the cycle, but two come back out. The overall process results in four protons (hydrogen nuclei) becoming a helium-4 nucleus, two positrons, two neutrinos and two gamma-rays. Teachers Notes Booklet 5: Stellar Processes and Evolution Page 5 of 16
6 Figure 5.1: Proton-Proton Chain Each helium-4 nucleus has a mass that is about 99.3% of the mass of four protons. In the Sun, for example, 600 million tons of hydrogen are converted into 596 million tons of helium every second. The missing four million tons of matter is released as energy in accordance with Einstein's equation E=mc 2. CNO Cycle In more massive stars (at least 4 solar masses) the Carbon-Nitrogen-Oxygen cycle dominates as the main process for proton burning proton. The heavier elements are already present in the star, therefore largely restricting this process to younger Population I stars. The CNO cycle occurs only in more massive stars due to the necessity of a convective core with a temperature of at least 20 million K. In the process a 12 C nucleus and four protons combine in various stages ultimately resulting in the creation of another 12 C nucleus, a helium nucleus and the liberation of a significant amount of energy. The carbon is acting as a catalyst in the process of converting hydrogen into helium. There is no net creation of the heavier elements through this process. Teachers Notes Booklet 5: Stellar Processes and Evolution Page 6 of 16
7 Figure 5.2: CNO Cycle Process Result Extras 1 carbon-12 + proton nitrogen-13 gamma-ray 2 nitrogen-13 decay carbon-13 neutrino, positron 3 carbon-13 + proton nitrogen-14 gamma-ray 4 nitrogen-14 + proton oxygen-15 gamma-ray 5 oxygen 15 decay nitrogen-15 neutrino, positron 6 nitrogen-15 + proton carbon-12 helium nucleus Table 5.2: CNO Cycle Reactions The Future? Once the stellar core has used up the majority of its hydrogen source the core region is dominated by helium. The future evolution of the star now depends very firmly on its mass and whether there is sufficient gravitational pressure to induce helium burning and the burning of successively heavier elements. Teachers Notes Booklet 5: Stellar Processes and Evolution Page 7 of 16
8 5.3 Evolution All stars, irrespective of their initial mass, spend the majority of their life consuming hydrogen. This period, which can last tens of billions of years, is the most stable time in the stellar lifecycle. The lifetime of a star depends largely on its mass. Somewhat counter intuitively, the more massive a star is the shorter its lifetime! Although massive stars contain a larger reservoir of fuel, the increased gravitational pressure in the core means an accelerated consumption rate. Table 5.3: Stellar Properties and Lifetime Star Type Temp (K) Mass Age O My B My A My F Gy G Gy K Gy M Gy As hydrogen converts into helium, so the composition of the stellar core changes. The initial ball of hydrogen becomes a ball of helium surrounded by a shell of hydrogen. Teachers Notes Booklet 5: Stellar Processes and Evolution Page 8 of 16
9 5.4 Paths on HR Diagram Figure 5.3: Evolutionary Paths Off the Main Sequence The HR diagram can be used to plot the changes in a stars brightness and temperature over time. All stars, irrespective of their mass spend most of their lifetime on the Main Sequence - the diagonal band spanning from top left to lower right. Stars of differing mass exist at different points along the main sequence. The more massive a star the further up and left it appears. As all stars enter a giant phase their brightness remains constant, but the effective surface temperature cools. This reflects a change in the process at work in the star. The outer layers have expanded and are no longer places of nuclear burning. As these layers cool, the star drifts towards the right side of the HR diagram. The subsequent evolution depends on the mass of the star. Low mass stars undergo an increase in luminosity, while more massive stars retain the same luminosity but have an oscillating surface temperature. Teachers Notes Booklet 5: Stellar Processes and Evolution Page 9 of 16
10 5.5 Solar Mass Stars A star, mass comparable to the Sun, with a core of pure helium and surrounded by a hydrogen shell, will continue evolve through helium burning. Since helium has two protons in its nucleus, compared to the one in hydrogen, a higher core temperature is necessary to overcome the electrostatic potential. As hydrogen burning comes to an end the core temperature is not sufficient for helium burning to occur. With no source of energy production in the core there is no longer any outward radiative pressure to resist gravitational collapse. As the outer regions start to collapse the temperature increases. This heat raises the temperature in hydrogen shell such that hydrogen fusion can occur. The core continues to collapse and the temperature in the hydrogen shell keeps on increasing and so the luminosity also increases. The core collapse is now fuelled by two sources gravity extends radiation pressure and the hydrogen burning shell also exerts a pressure. The burning shell also provides pressure on the outer layers of the star and causes them to expand. As the layers expand they cool and the star appears to become redder. After just a few million years the hydrogen shell will eventually run out of fuel. Once again the star will contract under its own weight. The compact core may flash into life for a short period and helium be fused into carbon. As the energy released in the helium flash reaches the outer layers the star becomes a red giant again and up to half its mass is thrown out into space and seen as a planetary nebula leaving a core behind. The core is a curious object. It weighs around half the mass the star had during its lifetime yet it is smaller in size than Uranus or Neptune. The core is also very hot, hotter again than when on the main sequence, yet produces no energy and will eventually cool down. The surface gravity can be in excess of times gravity on Earth. The average density is over 1000 kg per cubic centimetre causing the atoms to be packed so closely making the star electron degenerate. This star is known as a white dwarf. Teachers Notes Booklet 5: Stellar Processes and Evolution Page 10 of 16
11 Electron-degeneracy theory predicts that the uppermost mass a white dwarf can attain is about 1.44 times the mass of the Sun, called the Chandrasekhar Limit. Any heavier, and the tremendous pressure on the innermost atoms would squeeze their electrons into the nuclei they orbit, turning all the protons and electrons in the star into neutrons. The low surface area and high specific heat means that such an object would take longer than the currently estimated age of the Universe to cool. Teachers Notes Booklet 5: Stellar Processes and Evolution Page 11 of 16
12 5.6 Medium Mass Stars Stars with a mass of between 8 and 20 solar masses have a more complex evolution. Initially, they evolve in the same way as low mass stars, turning into red giants and undergoing a core helium burning phase. In medium mass stars, however, the burning of helium into carbon is no longer the end phase of stellar evolution. When the core helium supply is exhausted, the additional mass allows stellar collapse to take place and the outer layers to reignite. A cross section through the star at this point would show an outer shell of hydrogen burning, an inner shell of helium burning and the core, where there is now sufficient energy for the carbon to fuse with helium into oxygen. Once the carbon supply is exhausted so oxygen fuses into neon, the helium shell becomes a carbon burning shell, the hydrogen shell a helium shell and a new outer layer of hydrogen burning forms. Neon can then fuse into magnesium, into silicon, and so on to chromium into iron. Each of these stages produces less energy than the previous stage and lasts for less time. During these final stages the star expands to thousands of times the diameter of the Sun, becoming a red supergiant like Betelgeuse. The star finally hits a problem. To fuse iron into heavier elements requires an input of energy. Separating into the lighter elements again requires an input of energy. So as iron burning stars the core cools down it draws in heat from its surroundings to power the fusion. Suddenly the outward radiative pressure, which has supported the star for many millions of years, ceases and the star undergoes a free fall gravitational collapse. The core, which represents a large percentage of the stellar mass, now exceeds the 1.44 Chandrasekhar mass limit for a white dwarf. The protons and electrons in the core are compressed into a ball of neutrons, the size of a large city and the density of an atomic nucleus, held up by neutron degeneracy pressure. Such an object is a neutron star. As a result of the core collapse a shock wave forms and blasts out through the star releasing an enormous amount of energy in a few seconds. All the outer layers of the star become superheated plasmas, with temperatures high enough to fuse iron and heavier elements, like gold and uranium. These outer layers brighten rapidly and are ejected into the interstellar medium at speeds approaching the speed of light. Such events are witnessed as Type II Supernovae. Teachers Notes Booklet 5: Stellar Processes and Evolution Page 12 of 16
13 Pulsars A pulsar is a neutron star that produces pulsed emissions across the entire electromagnetic spectrum. Neutron stars spin rapidly and have large magnetic fields. Radiation channelled down the field lines is beamed out across the Universe like the light from a lighthouse. If the Earth happens to be in the light of sight then the emission is seen. Many pulsars spin rapidly with pulse durations of the order of fractions of a second. Teachers Notes Booklet 5: Stellar Processes and Evolution Page 13 of 16
14 5.7 High Mass Stars Stars with over 20 solar masses have an even more catastrophic end. They evolve in the same way as their slightly less massive companions dying in a supernova explosion, but the core evolves in a very different way. A neutron star can have up to around three solar masses. After this point neutron degeneracy pressure is no longer sufficient to prevent core collapse. With nothing left to resist collapse the core condenses into an infinitely small, infinitely dense point called a singularity. Nothing can escape from the singularity. Nothing that comes within three kilometres times the mass of the singularity in solar mass (the Schwarzchild Radius) can escape. The whole stellar core swallows itself, leaving behind a gravitational potential well. It is known as a black hole. Teachers Notes Booklet 5: Stellar Processes and Evolution Page 14 of 16
15 5.8 Other Materials This is booklet five in a series of six booklets currently available. The full range of titles is: Booklet 1 Booklet 2 Booklet 3 Booklet 4 Booklet 5 Booklet 6 Introduction to the Universe Stellar Radiation and Stellar Types Stellar Distances Cosmology Stellar Processes and Evolution Galaxies and the Expanding Universe Each booklet can be used to cover a topic on its own, or as part of a series. Booklets 5 and 6 expand on the material covered in the other booklets and there is, therefore, some overlap in content. All the booklets can be accessed via the ESA Science and Technology at: For other educational resources visit the ESA Science and Technology Educational Support website at: Teachers Notes Booklet 5: Stellar Processes and Evolution Page 15 of 16
16 Teachers Notes Booklet 5: Stellar Processes and Evolution Page 16 of 16
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 informationNSCI 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 information1. 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 informationAstronomy 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 informationReview: 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 informationLIFE 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,
More informationHigh 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
More informationLIFE 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,
More informationLife 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 informationPhysics 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 informationBirth and Death of Stars. Birth of Stars. Gas and Dust Clouds. Astronomy 110 Class 11
Birth and Death of Stars Astronomy 110 Class 11 Birth of Stars Start in cloud of gas and dust Contraction and Fragmentation Gravitational collapse and heating Protostar and disk Main Sequence Star Gas
More informationPhys 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 informationStar 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 informationCh. 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 informationBrock 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 informationExplain 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 informationThe 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 informationComparing 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 informationBrock 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 informationEvolution 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 informationProtostars 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 informationChapter 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 informationChapter 13 Notes The Deaths of Stars Astronomy Name: Date:
Chapter 13 Notes The Deaths of Stars Astronomy Name: Date: I. The End of a Star s Life When all the fuel in a star is used up, will win over pressure and the star will die nuclear fuel; gravity High-mass
More informationASTRONOMY 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 informationHeading 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 informationWhat 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 informationLife of a Star. Pillars of Creation
Life of a Star Life of a Star Pillars of Creation Life of a Star Pillars of Creation Stars form from massive clouds of gas that primarily consist of hydrogen. Life of a Star Gravity causes gas to contract
More information25.2 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 informationLow 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 informationThe 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 informationStars with Mⵙ go through two Red Giant Stages
Astronomy A. Dayle Hancock adhancock@wm.edu Small 239 Office hours: MTWR 10-11am Death of Stars Nuclear reactions in small stars How stars disperse carbon How low mass stars die The nature of white dwarfs
More informationSupernovae, Neutron Stars, Pulsars, and Black Holes
Supernovae, Neutron Stars, Pulsars, and Black Holes Massive stars and Type II supernovae Massive stars (greater than 8 solar masses) can create core temperatures high enough to burn carbon and heavier
More informationAstronomy 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 informationChapter 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 informationGalaxies Galore. Types of Galaxies: Star Clusters. Spiral spinning wit arms Elliptical roundish Irregular no set pattern
Stars Studying Stars Astronomers use a spectroscope to study the movement of stars Blue shift towards earth Red shift away from earth Change in a wavelength moving toward or away from earth is the Doppler
More information1 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 informationAstronomy Notes Chapter 13.notebook. April 11, 2014
All stars begin life in a similar way the only difference is in the rate at which they move through the various stages (depends on the star's mass). A star's fate also depends on its mass: 1) Low Mass
More informationProtostars 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 informationAstronomy 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 informationLife 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 informationToday The Sun. Events
Today The Sun Events Last class! Homework due now - will count best 5 of 6 Final exam Dec. 20 @ 12:00 noon here Review this Course! www.case.edu/utech/course-evaluations/ The Sun the main show in the solar
More informationMar 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 informationA Star is born: The Sun. SNC1D7-Space
A Star is born: The Sun SNC1D7-Space Exploring the Sun Our Sun, a star, is the most important celestial object for life on Earth. The solar nebula theory is the current theory used to explain the formation
More informationExam # 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 informationUniverse Now. 7. Stars: classification, formation, energy production, and evolution
Universe Now 7. Stars: classification, formation, energy production, and evolution Stars in the sky By naked eye: In optimal circumstances 3000 5000 stars, in Finland 1000 1500, in the light pollution
More informationLife 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 informationChapter 14: The Bizarre Stellar Graveyard. Copyright 2010 Pearson Education, Inc.
Chapter 14: The Bizarre Stellar Graveyard Assignments 2 nd Mid-term to be held Friday Nov. 3 same basic format as MT1 40 mult. choice= 80 pts. 4 short answer = 20 pts. Sample problems on web page Origin
More informationChapters 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 informationStellar 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 informationLife 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 informationHigh Mass Stars and then Stellar Graveyard 7/16/09. Astronomy 101
High Mass Stars and then Stellar Graveyard 7/16/09 Astronomy 101 Astronomy Picture of the Day Astronomy 101 Something Cool Betelgeuse Astronomy 101 Outline for Today Astronomy Picture of the Day Something
More informationStar 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 informationStellar 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 information8/30/2010. 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 informationThe 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 informationIntroduction 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 informationChapter 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 informationMissing words: mass hydrogen burning electrostatic repulsion. gravitationally hydrogen temperature protostar
Instructions Fill in the blanks of each frame using the list of missing words given. Cut out each frame and arrange them on your page in order, then stick them down. The first two frames are already in
More informationUniverse Celestial Object Galaxy Solar System
ASTRONOMY Universe- Includes all known matter (everything). Celestial Object Any object outside or above Earth s atmosphere. Galaxy- A large group (billions) of stars (held together by gravity). Our galaxy
More informationEarth Space Systems. Semester 1 Exam. Astronomy Vocabulary
Earth Space Systems Semester 1 Exam Astronomy Vocabulary Astronomical Unit- Aurora- Big Bang- Black Hole- 1AU is the average distance between the Earth and the Sun (93 million miles). This unit of measurement
More informationStars 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
More informationthe 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 informationPage 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
More informationGuiding 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 information10/26/ Star Birth. Chapter 13: Star Stuff. How do stars form? Star-Forming Clouds. Mass of a Star-Forming Cloud. Gravity Versus Pressure
10/26/16 Lecture Outline 13.1 Star Birth Chapter 13: Star Stuff How do stars form? Our goals for learning: How do stars form? How massive are newborn stars? Star-Forming Clouds Stars form in dark clouds
More informationTEACHER BACKGROUND INFORMATION
TEACHER BACKGROUND INFORMATION (The Universe) A. THE UNIVERSE: The universe encompasses all matter in existence. According to the Big Bang Theory, the universe was formed 10-20 billion years ago from a
More informationAstronomy 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 informationPlanetary 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 informationWhy 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 informationProperties 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 informationLow-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
More informationThe ESA Science Programme currently contains the following active missions:
Teachers Notes Booklet 2: Stellar Radiation and Stellar Types Page 1 of 19 The European Space Agency The European Space Agency (ESA) was formed on 31 May 1975. It currently has 17 Member States: Austria,
More informationBeyond 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 informationASTR 1P02 Test 1, February 2017 Page 1 BROCK UNIVERSITY
ASTR 1P02 Test 1, February 2017 Page 1 BROCK UNIVERSITY Test 1: February 2017 Number of pages: 10 Course: ASTR 1P02, Section 2 Number of students: 1200 Examination date: 4 February 2017 Time limit: 50
More informationA 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 informationNSB ideas on Hertzsprung-Russell diagram
Contents Big ideas Not so big ideas about the sun Not so big ideas about Hertzsprung-Russell diagram Not so big ideas about white dwarfs, neutron stars, and black holes Questions on chapter 10, 11, 12,
More informationAstro 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 informationInstructions. Students will underline the portions of the PowerPoint that are underlined.
STARS Instructions Students will underline the portions of the PowerPoint that are underlined. Nuclear Furnace 1. A star is like a gigantic nuclear furnace. 2. The nuclear reactions inside convert hydrogen
More informationProtostars 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 informationASTR Midterm 1 Phil Armitage, Bruce Ferguson
ASTR 1120-001 Midterm 1 Phil Armitage, Bruce Ferguson FIRST MID-TERM EXAM FEBRUARY 16 th 2006: Closed books and notes, 1 hour. Please PRINT your name and student ID on the places provided on the scan sheet.
More information10/29/2009. 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 informationStar Death ( ) High Mass Star. Red Supergiant. Supernova + Remnant. Neutron Star
Star Death High Mass Star Red Supergiant A star with mass between 8 M and 20 M will become a red supergiant and will subsequently experience a supernova explosion. The core of this star will have a mass
More informationThe 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 informationLife and Evolution of a Massive Star. M ~ 25 M Sun
Life and Evolution of a Massive Star M ~ 25 M Sun Birth in a Giant Molecular Cloud Main Sequence Post-Main Sequence Death The Main Sequence Stars burn H in their cores via the CNO cycle About 90% of a
More informationCh. 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 informationStar Formation and Evolution
Star Formation and Evolution Low and Medium Mass Stars Four Components of the Interstellar Medium Component Temperature Density (K) (atoms/cm 3 ) HI Clouds 50 150 1 1000 Intercloud Medium 10 3-10 4 0.01
More informationChapter 12: The Life Cycle of Stars (contʼd) How are stars born, and how do they die? 4/9/09 Habbal Astro Lecture 25 1
Chapter 12: The Life Cycle of Stars (contʼd) How are stars born, and how do they die? 4/9/09 Habbal Astro 110-01 Lecture 25 1 12.3 Life as a High-Mass Star Learning Goals What are the life stages of a
More informationLecture 16: The life of a low-mass star. Astronomy 111 Monday October 23, 2017
Lecture 16: The life of a low-mass star Astronomy 111 Monday October 23, 2017 Reminders Online homework #8 due Monday at 3pm Exam #2: Monday, 6 November 2017 The Main Sequence ASTR111 Lecture 16 Main sequence
More informationChapter 18 The Bizarre Stellar Graveyard
Chapter 18 The Bizarre Stellar Graveyard 18.1 White Dwarfs Our goals for learning What is a white dwarf? What can happen to a white dwarf in a close binary system? What is a white dwarf? White Dwarfs White
More informationX-Ray Spectroscopy of Supernova Remnants. Introduction and Background:
X-Ray Spectroscopy of Supernova Remnants Introduction and Background: RCW 86 (Chandra, XMM-Newton) RCW 86 is a supernova remnant that was created by the destruction of a star approximately two thousand
More informationThe life of a low-mass star. Astronomy 111
Lecture 16: The life of a low-mass star Astronomy 111 Main sequence membership For a star to be located on the Main Sequence in the H-R diagram: must fuse Hydrogen into Helium in its core. must be in a
More informationIntroductory 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
More informationOutline - 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
More informationGravity simplest. fusion
Gravity simplest fusion The life of a star has a complex relationship with gravity: 1. Gravity is what brings the original dust together to make a star 2. Gravity wants to crush the star Gravity pulls
More information1. Star: A object made of gas found in outer space that radiates.
1. Star: A object made of gas found in outer space that radiates. 2. Stars produce extremely great quantities of energy through the process of. The chemical formula for nuclear fusion looks like this:
More informationBirth & 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 informationTeachers Notes Booklet 6: Galaxies and the Expanding Universe Page 1 of 18
Teachers Notes Booklet 6: Galaxies and the Expanding Universe Page 1 of 18 The European Space Agency The European Space Agency (ESA) was formed on 31 May 1975. It currently has 17 Member States: Austria,
More informationStars 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
More informationStellar 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 informationNotes for Wednesday, July 16; Sample questions start on page 2 7/16/2008
Notes for Wednesday, July 16; Sample questions start on page 2 7/16/2008 Wed, July 16 MW galaxy, then review. Start with ECP3Ch14 2 through 8 Then Ch23 # 8 & Ch 19 # 27 & 28 Allowed Harlow Shapely to locate
More information