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

Size: px
Start display at page:

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

Transcription

1 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 & lose mass Star clusters reveal formation & evolution details Protostars can form in giant molecular clouds Supernovae can trigger star birth Stellar Observations & Theories Fundamental observational difficulties Stars exist far longer than astronomers Star lifetimes range from millions to billions of years Stellar birth, life & death observed as stages Each observation is an extremely brief snapshot Fundamental observational simplicity Every star is far simpler than any living organism The materials are very simple The processes are very simple Basic physical processes Gravity tends to gather matter closer together Gravity is determined by distance between atoms Pressure tends to disperse matter farther apart Pressure is determined by temperature of atoms Interstellar Gas & Dust in Our Galaxy Emission nebulae Fluorescence similar to common light bulbs Emission lines depend on material & temperature Reflection nebulae Characteristic blue color Selective scattering of continuous spectra from stars Dust particles comparable in size to blue wavelengths Dark nebulae Characteristic blocking of background light May be partial or total blocking Thermal infrared can penetrate some dark nebulae Initiation of Star Formation Compression of interstellar medium is essential Gentle mechanisms from low-mass star death Gently expanding shell of gas called a planetary nebula Weak shock wave may initiate compression Gas adds low-mass elements to the forming stars Usually limited to Carbon & Silicon Violent mechanisms from high-mass star death Rapidly expanding gas shell is a supernova remnant Strong shock wave will initiate formation of O & B stars Gas adds high-mass elements to the forming stars May include elements as heavy as Uranium The Orion Nebula: A Close-Up View Emission, Reflection & Dark Nebulae

2 Reflection Nebula In Corona Australis Interstellar Reddening by Dust Grains Strongly scattered Weakly scattered Spiral Galaxies: Two Perspectives Face-on Edge-on Protostars Form in Cold Dark Nebulae Basic physical processes Gravity effects must exceed pressure effects Highest probability for star formation Extremely low temperatures minimize pressure Extremely close atoms maximize gravity Only dark nebulae have high enough density Large Barnard objects A few thousand M & ~ 10 pc in diameter Small Bok globules Resembles the core of a Barnard object Basic chemical composition (by mass) ~ 74% hydrogen ~ 25% helium ~ 1% metals All elements heavier than helium Bok Globules: Opaque Dust & Gas Anglo-Australian Observatory Protostar Details Earliest model Henyey & Hayashi 1950 s Stage 1 Cool nebula several times Solar System size Stage 2 Continued contraction raises the temperature Kelvin-Helmholtz contraction Stage 3 Still quite large, the cloud begins to glow Convection move heat outward Low temperature + Huge surface = Very bright A protostar the mass of the Sun After 1,000 years of contraction Surface temperature is ~ 2,000 K to 3,000 K Diameter is ~ 20 times > the Sun Luminosity is ~ 100 times > the Sun

3 Evolutionary Track of Protostars High- mass stars Approximately a horizontal line on an H-R diagram Progression is toward the left Cool to hot Solar- mass stars Approximately a V-shaped line on an H-R diagram Progression is toward the left Cool to hot Low- mass stars Approximately a vertical line on an H-R diagram Progression is toward the bottom Bright to dim Pre-Main-Sequence Evolutionary Tracks Progress of Star Formation A positive feedback process Gravity & pressure increase as the nebula shrinks Pressure increases d Gravity increases d 2 Gravity overwhelms pressure Magnetism could disrupt this in the earliest stages Additional characteristics Angular momentum is conserved The shrinking nebula spins faster & faster Original 3-D cloud deforms into a donut-like disk Material spins inward very rapidly Much of this material is ejected at the protostar s poles Culmination of Star Formation A negative feedback process High core pressure & temperature sustain H fusion A new & intense source of heat energy Core pressure rises dramatically Gravitational collapse ends Thermal & hydrostatic equilibrium established A new star stabilizes on the main sequence Protostars Become Main-Sequence Stars Protostar temperature changes Surface Little temperature change Minimal increase for 15 M protostars Slight increase for 5 M protostars Slight decrease for 2 M protostars Significant decrease for 1 M protostars Dramatic decrease for 0.5 M protostars Core Dramatic temperature increase Increasing temperature ionizes the protostar s interior Energy is transmitted outward by radiation Temperatures > several million kelvins initiate fusion This event marks the birth of a true star Protostar Evolution is Mass-Dependent Very-low- mass stars M < 0.8 M Core temperatures too low to ionize interior Convection characterizes the entire interior of the star Low- mass stars 0.8 M Sun < M < 4 M Core temperatures high enough to ionize interior Radiation characterizes the region surrounding the core Convection characterizes the region near the surface High- mass stars M > 4 M Hydrogen fusion begins very early Convection characterizes the region surrounding the core Radiation characterizes the region near the surface

4 Main-Sequence Stars of Different Mass Brown Dwarfs: Failed Stars A minimum mass is required for fusion Pressure & temperature cannot get high enough Minor lithium fusion can occur Surface temperature may reach ~ 2,000 K Brown dwarf characteristics Mass between kg & kg ~ 10 to 84 times the mass of Jupiter The lower mass limit is sometimes set at ~ 14 times M Jup Continues to cool & contract Detectable only at thermal infrared wavelengths Many brown dwarfs exhibit irregular brightness changes Possible storms far more violent than on Jupiter Protostars Both Gain & Lose Mass Protostar formation is extremely dynamic Matter is drawn inward along an accretion disk Matter is hurled outward perpendicular to this disk T Tauri stars 20 th brightest star in the constellation Taurus Exhibit both emission & absorption spectral lines Surrounded by hot low-density gas Doppler shift indicates a velocity of 80 km. sec -1 Luminosity varies irregularly over several days Mass ~ 3 M Herbig-Haro objects Bipolar outflow compresses & heats interstellar gas May last only ~ 10,000 to 100,000 years Herbig-Haro Objects: Bipolar Outflow Clusters Reveal Formation & Evolution Star clusters never have stars of uniform mass High-mass stars evolve very quickly O & B spectral class stars emit abundant UV radiation Low-mass stars evolve very slowly K & M spectral class stars emit abundant IR radiation The destiny of excess gas & dust H II regions H I regions are neutral (non-ionized) hydrogen H II regions are singly-ionized hydrogen Hydrogen has only 1 electron Result is free protons & electrons Produce red emission nebulae Dust regions Resist dissipation by strong UV radiation from O & B stars Produce blue reflection nebulae A Star Cluster With An H II Region

5 H-R Diagram of a Young Star Cluster The Pleiades & Its H-R Diagram Protostars In Giant Molecular Clouds Characteristics of molecular clouds 195 different molecules identified in space ~ 10,000 H 2 molecules for every CO molecule The Milky Way contains ~ 5,000 molecular clouds These include several star-forming regions 17 molecular clouds outline the local arm of our galaxy Orion nebula s parent cloud contains ~ 500,000 M Spectral emission lines Cold dark interstellar hydrogen clouds Emission in the UV, visible & IR regions of the spectrum Molecular interstellar gas clouds Emission in the microwave region of the spectrum Carbon Monoxide Molecular Clouds Molecular Clouds in the Milky Way O & B Stars Trigger Star Formation

6 Supernovae Can Trigger Star Birth Supernova remnants are common High-mass stars exhaust their H 2 supply very quickly Many old star clusters have supernova remnants Supernova remnants are violent High-mass stars die in tremendous explosions Spherical shock wave goes outward at supersonic speeds This compresses interstellar gas & dust clouds Often results in associations rather than clusters New stars are moving too fast to stay gravitationally bound New stars quickly disperse in various directions Probably the situation when our Sun formed Supernova Remnant in the Cygnus Loop Important Concepts Interstellar gas & dust Emission, reflection & dark nebulae Potential birthplace of stars Stages of star formation Initiation Coldest & densest regions are ideal Contest between gravity & pressure Compression mechanism required Progress Positive feedback: Gravity > Pressure Collapse accelerates until fusion Culmination Heat from fusion increases pressure Equilibrium is established Protostar evolution depends on mass Very-low- mass < 0.8 times M Sun Low- mass < 4 times M Sun High- mass > 4 times M Sun Mass gain & loss in protostars Circumstellar accretion disk inflows Bipolar outflows T Tauri [variable] stars Herbig-Haro objects Star clusters give evolution details Few clusters have same-age stars Luminosity & color on H-R diagram Stellar models fit observations well Star formation in molecular clouds ~ 5,000 in the Milky Way galaxy 17 define our galactic spiral arm Compression mechanisms UV emissions from OB associations Supernova explosions

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

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

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

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

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

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

Chapter 11 The Formation and Structure of Stars

Chapter 11 The Formation and Structure of Stars Chapter 11 The Formation and Structure of Stars Guidepost The last chapter introduced you to the gas and dust between the stars that are raw material for new stars. Here you will begin putting together

More information

Stellar Birth. Stellar Formation. A. Interstellar Clouds. 1b. What is the stuff. Astrophysics: Stellar Evolution. A. Interstellar Clouds (Nebulae)

Stellar Birth. Stellar Formation. A. Interstellar Clouds. 1b. What is the stuff. Astrophysics: Stellar Evolution. A. Interstellar Clouds (Nebulae) Astrophysics: Stellar Evolution 1 Stellar Birth Stellar Formation A. Interstellar Clouds (Nebulae) B. Protostellar Clouds 2 C. Protostars Dr. Bill Pezzaglia Updated: 10/02/2006 A. Interstellar Clouds 1.

More information

Chapter 16 Lecture. The Cosmic Perspective Seventh Edition. Star Birth Pearson Education, Inc.

Chapter 16 Lecture. The Cosmic Perspective Seventh Edition. Star Birth Pearson Education, Inc. Chapter 16 Lecture The Cosmic Perspective Seventh Edition Star Birth 2014 Pearson Education, Inc. Star Birth The dust and gas between the star in our galaxy is referred to as the Interstellar medium (ISM).

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

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

Astro 1050 Wed. Apr. 5, 2017

Astro 1050 Wed. Apr. 5, 2017 Astro 1050 Wed. Apr. 5, 2017 Today: Ch. 17, Star Stuff Reading in Horizons: For Mon.: Finish Ch. 17 Star Stuff Reminders: Rooftop Nighttime Observing Mon, Tues, Wed. 1 Ch.9: Interstellar Medium Since stars

More information

Chapter 9. The Formation and Structure of Stars

Chapter 9. The Formation and Structure of Stars Chapter 9 The Formation and Structure of Stars 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

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

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

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

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

The Ecology of Stars

The Ecology of Stars The Ecology of Stars We have been considering stars as individuals; what they are doing and what will happen to them Now we want to look at their surroundings And their births 1 Interstellar Matter Space

More information

Atoms and Star Formation

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

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

Remember from Stefan-Boltzmann that 4 2 4

Remember from Stefan-Boltzmann that 4 2 4 Lecture 17 Review Most stars lie on the Main sequence of an H&R diagram including the Sun, Sirius, Procyon, Spica, and Proxima Centauri. This figure is a plot of logl versus logt. The main sequence is

More information

Astronomy 1 Fall 2016

Astronomy 1 Fall 2016 Astronomy 1 Fall 2016 Lecture11; November 1, 2016 Previously on Astro-1 Introduction to stars Measuring distances Inverse square law: luminosity vs brightness Colors and spectral types, the H-R diagram

More information

10/26/ Star Birth. Chapter 13: Star Stuff. How do stars form? Star-Forming Clouds. Mass of a Star-Forming Cloud. Gravity Versus Pressure

10/26/ 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 information

Clicker Question: Clicker Question: What is the expected lifetime for a G2 star (one just like our Sun)?

Clicker Question: Clicker Question: What is the expected lifetime for a G2 star (one just like our Sun)? How Long do Stars Live (as Main Sequence Stars)? A star on Main Sequence has fusion of H to He in its core. How fast depends on mass of H available and rate of fusion. Mass of H in core depends on mass

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

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

8. Solar System Origins

8. Solar System Origins 8. Solar System Origins Chemical composition of the galaxy The solar nebula Planetary accretion Extrasolar planets Our Galaxy s Chemical Composition es Big Bang produced hydrogen & helium Stellar processes

More information

Chapter 16 Lecture. The Cosmic Perspective Seventh Edition. Star Birth Pearson Education, Inc.

Chapter 16 Lecture. The Cosmic Perspective Seventh Edition. Star Birth Pearson Education, Inc. Chapter 16 Lecture The Cosmic Perspective Seventh Edition Star Birth Star Birth 16.1 Stellar Nurseries Our goals for learning: Where do stars form? Why do stars form? Where do stars form? Star-Forming

More information

AST 101 INTRODUCTION TO ASTRONOMY SPRING MIDTERM EXAM 2 TEST VERSION 1 ANSWERS

AST 101 INTRODUCTION TO ASTRONOMY SPRING MIDTERM EXAM 2 TEST VERSION 1 ANSWERS AST 101 INTRODUCTION TO ASTRONOMY SPRING 2008 - MIDTERM EXAM 2 TEST VERSION 1 ANSWERS Multiple Choice. In the blanks provided before each question write the letter for the phrase that best answers the

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

Universe Now. 9. Interstellar matter and star clusters

Universe Now. 9. Interstellar matter and star clusters Universe Now 9. Interstellar matter and star clusters About interstellar matter Interstellar space is not completely empty: gas (atoms + molecules) and small dust particles. Over 10% of the mass of the

More information

Chapter 16: Star Birth

Chapter 16: Star Birth Chapter 16 Lecture Chapter 16: Star Birth Star Birth 16.1 Stellar Nurseries Our goals for learning: Where do stars form? Why do stars form? Where do stars form? Star-Forming Clouds Stars form in dark clouds

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

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

Star-Forming Clouds. Stars form in dark clouds of dusty gas in interstellar space. The gas between the stars is called the interstellar medium.

Star-Forming Clouds. Stars form in dark clouds of dusty gas in interstellar space. The gas between the stars is called the interstellar medium. Star Birth Chapter 16 Lecture 16.1 Stellar Nurseries The Cosmic Perspective Our goals for learning: Where do stars form? Why do stars form? Seventh Edition Star Birth Where do stars form? Star-Forming

More information

The Interstellar Medium. Papillon Nebula. Neutral Hydrogen Clouds. Interstellar Gas. The remaining 1% exists as interstellar grains or

The Interstellar Medium. Papillon Nebula. Neutral Hydrogen Clouds. Interstellar Gas. The remaining 1% exists as interstellar grains or The Interstellar Medium About 99% of the material between the stars is in the form of a gas The remaining 1% exists as interstellar grains or interstellar dust If all the interstellar gas were spread evenly,

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

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

Chapter 12: The Lives of Stars. How do we know it s there? Three Kinds of Nebulae 11/7/11. 1) Emission Nebulae 2) Reflection Nebulae 3) Dark Nebulae 11/7/11 Chapter 12: The Lives of Stars Space is Not Empty The Constellation Orion The Orion Nebula This material between the stars is called the Interstellar Medium It is very diffuse and thin. In fact

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

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

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

THE INTERSTELLAR MEDIUM

THE INTERSTELLAR MEDIUM THE INTERSTELLAR MEDIUM An IR view of dust clouds In particular, light from polycyclic aromatic hydrocarbons (PAH s) Little bit of carbon out there, forms hydrocarbons like car exhaust Associated with

More information

Chapter 11 The Formation of Stars

Chapter 11 The Formation of Stars Chapter 11 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.

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

Energy. mosquito lands on your arm = 1 erg. Firecracker = 5 x 10 9 ergs. 1 stick of dynamite = 2 x ergs. 1 ton of TNT = 4 x ergs

Energy. mosquito lands on your arm = 1 erg. Firecracker = 5 x 10 9 ergs. 1 stick of dynamite = 2 x ergs. 1 ton of TNT = 4 x ergs Energy mosquito lands on your arm = 1 erg Firecracker = 5 x 10 9 ergs 1 stick of dynamite = 2 x 10 13 ergs 1 ton of TNT = 4 x 10 16 ergs 1 atomic bomb = 1 x 10 21 ergs Magnitude 8 earthquake = 1 x 10 26

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

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

Astr 2310 Thurs. March 23, 2017 Today s Topics

Astr 2310 Thurs. March 23, 2017 Today s Topics Astr 2310 Thurs. March 23, 2017 Today s Topics Chapter 16: The Interstellar Medium and Star Formation Interstellar Dust and Dark Nebulae Interstellar Dust Dark Nebulae Interstellar Reddening Interstellar

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

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

Page 386 SUMMARY. 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 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

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

CHAPTER 29: STARS BELL RINGER:

CHAPTER 29: STARS BELL RINGER: CHAPTER 29: STARS BELL RINGER: Where does the energy of the Sun come from? Compare the size of the Sun to the size of Earth. 1 CHAPTER 29.1: THE SUN What are the properties of the Sun? What are the layers

More information

Midterm Results. The Milky Way in the Infrared. The Milk Way from Above (artist conception) 3/2/10

Midterm Results. The Milky Way in the Infrared. The Milk Way from Above (artist conception) 3/2/10 Lecture 13 : The Interstellar Medium and Cosmic Recycling Midterm Results A2020 Prof. Tom Megeath The Milky Way in the Infrared View from the Earth: Edge On Infrared light penetrates the clouds and shows

More information

The Universe. But first, let s talk about light! 2012 Pearson Education, Inc.

The Universe. But first, let s talk about light! 2012 Pearson Education, Inc. The Universe But first, let s talk about light! Light is fast! The study of light All forms of radiation travel at 300,000,000 meters (186,000 miles) per second Since objects in space are so far away,

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

Based on the reduction of the intensity of the light from a star with distance. It drops off with the inverse square of the distance.

Based on the reduction of the intensity of the light from a star with distance. It drops off with the inverse square of the distance. 6/28 Based on the reduction of the intensity of the light from a star with distance. It drops off with the inverse square of the distance. Intensity is power per unit area of electromagnetic radiation.

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

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

Gravitational collapse of gas

Gravitational collapse of gas Gravitational collapse of gas Assume a gas cloud of mass M and diameter D Sound speed for ideal gas is c s = γ P ρ = γ nkt ρ = γ kt m Time for sound wave to cross the cloud t sound = D == D m c s γ kt

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

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

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

Number of Stars: 100 billion (10 11 ) Mass : 5 x Solar masses. Size of Disk: 100,000 Light Years (30 kpc)

Number of Stars: 100 billion (10 11 ) Mass : 5 x Solar masses. Size of Disk: 100,000 Light Years (30 kpc) THE MILKY WAY GALAXY Type: Spiral galaxy composed of a highly flattened disk and a central elliptical bulge. The disk is about 100,000 light years (30kpc) in diameter. The term spiral arises from the external

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

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

Where do Stars Form?

Where do Stars Form? Where do Stars Form? Coldest spots in the galaxy: T ~ 10 K Composition: Mainly molecular hydrogen 1% dust EGGs = Evaporating Gaseous Globules ftp://ftp.hq.nasa.gov/pub/pao/pressrel/1995/95-190.txt Slide

More information

Today. When does a star leave the main sequence?

Today. When does a star leave the main sequence? ASTR 1040 Accel Astro: Stars & Galaxies Prof. Juri Toomre TA: Nick Featherstone Lecture 13 Tues 27 Feb 07 zeus.colorado.edu/astr1040-toomre toomre Crab Nebula -- Supernova Remnant Today Recall that C-N-O

More information

Name Date Period. 10. convection zone 11. radiation zone 12. core

Name Date Period. 10. convection zone 11. radiation zone 12. core 240 points CHAPTER 29 STARS SECTION 29.1 The Sun (40 points this page) In your textbook, read about the properties of the Sun and the Sun s atmosphere. Use each of the terms below just once to complete

More information

The Electromagnetic Spectrum

The Electromagnetic Spectrum The Electromagnetic Spectrum Three Kinds of Spectra Sun: The Nearest Star Radius 696,000 km 109 Re Mass 2 x 10^30 kg 300,000 Me Density 1400 kg/m^3 Luminosity 3.8x10^26 Watts (board calc.) Comp. 70% H,

More information

Ch. 25 In-Class Notes: Beyond Our Solar System

Ch. 25 In-Class Notes: Beyond Our Solar System Ch. 25 In-Class Notes: Beyond Our Solar System ES2a. The solar system is located in an outer edge of the disc-shaped Milky Way galaxy, which spans 100,000 light years. ES2b. Galaxies are made of billions

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

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

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

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

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

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

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

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

AST 101 Introduction to Astronomy: Stars & Galaxies

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

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

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

Chapter 19: Our Galaxy

Chapter 19: Our Galaxy Chapter 19 Lecture Chapter 19: Our Galaxy Our Galaxy 19.1 The Milky Way Revealed Our goals for learning: What does our galaxy look like? How do stars orbit in our galaxy? What does our galaxy look like?

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

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

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

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

The Life and Death of Stars

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

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

Accretion Disks. Review: Stellar Remnats. Lecture 12: Black Holes & the Milky Way A2020 Prof. Tom Megeath 2/25/10. Review: Creating Stellar Remnants

Accretion Disks. Review: Stellar Remnats. Lecture 12: Black Holes & the Milky Way A2020 Prof. Tom Megeath 2/25/10. Review: Creating Stellar Remnants Lecture 12: Black Holes & the Milky Way A2020 Prof. Tom Megeath Review: Creating Stellar Remnants Binaries may be destroyed in white dwarf supernova Binaries be converted into black holes Review: Stellar

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

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

Our Galaxy. Milky Way Galaxy = Sun + ~100 billion other stars + gas and dust. Held together by gravity! The Milky Way with the Naked Eye

Our Galaxy. Milky Way Galaxy = Sun + ~100 billion other stars + gas and dust. Held together by gravity! The Milky Way with the Naked Eye Our Galaxy Milky Way Galaxy = Sun + ~100 billion other stars + gas and dust Held together by gravity! The Milky Way with the Naked Eye We get a special view of our own galaxy because we are part of it!

More information

Stars and their properties: (Chapters 11 and 12)

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

More information

Stars, Galaxies & the Universe Lecture Outline

Stars, Galaxies & the Universe Lecture Outline Stars, Galaxies & the Universe Lecture Outline A galaxy is a collection of 100 billion stars! Our Milky Way Galaxy (1)Components - HII regions, Dust Nebulae, Atomic Gas (2) Shape & Size (3) Rotation of

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

The Interstellar Medium (ch. 18)

The Interstellar Medium (ch. 18) The Interstellar Medium (ch. 18) The interstellar medium (ISM) is all the gas (and about 1% dust) that fills our Galaxy and others. It is the raw material from which stars form, and into which stars eject

More information

Spiral Density waves initiate star formation

Spiral Density waves initiate star formation Spiral Density waves initiate star formation A molecular cloud passing through the Sagittarius spiral arm Spiral arm Gas outflows from super supernova or O/B star winds Initiation of star formation Supernova

More information

Stellar Evolution. Stars are chemical factories The Earth and all life on the Earth are made of elements forged in stars

Stellar Evolution. Stars are chemical factories The Earth and all life on the Earth are made of elements forged in stars Lecture 11 Stellar Evolution Stars are chemical factories The Earth and all life on the Earth are made of elements forged in stars A Spiral Galaxy (Milky Way Type) 120,000 ly A few hundred billion stars

More information

Stars: Their Life and Afterlife

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

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

Gas 1: Molecular clouds

Gas 1: Molecular clouds Gas 1: Molecular clouds > 4000 known with masses ~ 10 3 to 10 5 M T ~ 10 to 25 K (cold!); number density n > 10 9 gas particles m 3 Emission bands in IR, mm, radio regions from molecules comprising H,

More information