Gas 1: Molecular clouds

Size: px
Start display at page:

Download "Gas 1: Molecular clouds"

Transcription

1 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, C, O: H 2, CO, OH, NH 3, H 2 O, H 2 CO,... C 2 H 5 OH,... Dark dust clouds: star formation regions e.g. Orion & Taurus molecular clouds Mostly in spiral arms

2 Gas 1: Molecular clouds Seen in absorption against background stars

3 Gas 1: Molecular clouds Seen in reflection and absorption against bright nebular background

4 Molecular Clouds in the Milky Way Total intensity of CO emission Clouds mostly confined to midplane Very irregular

5 Molecular Clouds in the Milky Way Midplane emission vs radial velocity: spiral arms

6 Atomic Hydrogen Gas 2: HI clouds Well distributed through MW plane, < 200 pc thick. T ~ 100 K; Average n ~ 10 6 to 10 9 particles m 3 Detected by emission at 21 cm = 1420 MHz in radio region from HI in very low energy state: ev n=2 Energy above ground state Lyman-α (121.5 nm) ENERGY LEVEL DIAGRAM 6x10 6 ev 0 21 cm n=1 Spins parallel Spins anti-parallel p e

7 The 21-cm line H atoms excited by collisions to slightly higher energy level -- once per ~10 6 years per H atom Average lifetime in excited state ~ 10 7 years......followed by spontaneous decay back to ground state, emitting radiation at λ = 21 cm But ~ H atoms in MW plane... hence observable line emission All sky surveys mapping 21-cm emission provide: column densities of HI (no of atoms per m 2 along line of sight) Doppler shifts of moving HI clouds Get distribution of HI in the MW Galaxy, and the rotation curve -- determine circular speed as a function of distance from Galactic Centre (more later)

8 Neutral Hydrogen Clouds Shell surrounding supernova explosion Canadian Galactic Plane Survey

9 Neutral Hydrogen Clouds Mushroom cloud Canadian Galactic Plane Survey

10 The Milky Way in Neutral Hydrogen

11 Gas 3: HII regions H ionized by UV radiation from nearby hot, young stars: spectral types O & B Ionized volume ~ ionizing luminosity, L i = number of ionizing photons per second If cloud has constant density, get spherical ionized volume: Stromgren Sphere V S = 4 π R S 3 /3 ~ L i, so R S ~ L i 1/3 HII region T ~ 10 4 K O star R S Surrounding HI T ~ 100 K Spectral Type O6 B0 n ISM = 1 per cm 3 T eff (K) 45,000 25,000 R S > 100 pc 20 pc A0 10,000 1 pc BUT ISM and molecular clouds are not uniform

12 Size of a Stromgren Sphere L i = 4π 3 R3 n e n p α L i = ionizing luminosity: [photons per second] R = ionized radius (spherical): [m] n = number densities of electrons, protons: [m -3 ] α = recombination coefficient: [m 3 s -1 ] Calculate R if L i = s -1, n = 1 cm -3, α = 2.6x10-19 m 3 s -1

13 H II Regions: Observations & Theory

14 Orion Nebula

15 Tarantula Nebula

16

17 Stromgren Sphere: Hα

18 Gas 3: HII regions In photoionization equilibrium: H + captures e - and recombines, then ionized, then recombines,.. Electron cascades through various energy levels, emitting radiation at radio, optical, UV wavelengths HII regions found on edges of cold molecular clouds e.g. Orion Nebula is a blister HII region Molecular cloud HII region O star Surrounding HI HII regions + CO emission from molecular clouds identify spiral arm regions: sites of star formation

19 Orion Nebula Face-on view of a blister HII region Stellar winds from the four Trapezium O stars, carve cavity in molecular cloud Trapezium stars ionize face of cavity Ionized gas glows in emission lines Thousands of low mass stars and circumstellar disks in cluster in addition to Trapezium stars: stellar nursery

20 Orion Nebula: The Movie! Walt Feimer Space Telescope Science Institute

21 Protoplanetary Disks in Orion

22

23 Gas 4: Coronal gas T up to 10 6 K; Average n < 10 6 particles m 3. From SN remnants; form interconnecting tunnels around cooler clouds Seen by absorption lines from ground states of highly-ionized atoms (e.g. OVI, NV) superposed on spectra of hot stars in background Continuum radio emission from synchrotron radiation. X-ray emission ISM has the morphology of Swiss cheese

24 Molecular clouds, T ~ 10 K, molecular emission (H 2, CO, etc) HI, T ~ 100 K, 21 cm emission line HII, T ~ 10 4 K, emission lines from H, N, O, S Hot gas from supernova explosions, T ~ 10 6 K, see absorption lines on spectrum from background stars. Also observe diffuse X-Ray emission.

The Interstellar Medium

The Interstellar Medium http://www.strw.leidenuniv.nl/~pvdwerf/teaching/ The Interstellar Medium Lecturer: Dr. Paul van der Werf Fall 2014 Oortgebouw 565, ext 5883 pvdwerf@strw.leidenuniv.nl Assistant: Kirstin Doney Huygenslaboratorium

More information

Interstellar Medium and Star Birth

Interstellar Medium and Star Birth Interstellar Medium and Star Birth Interstellar dust Lagoon nebula: dust + gas Interstellar Dust Extinction and scattering responsible for localized patches of darkness (dark clouds), as well as widespread

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

Some HI is in reasonably well defined clouds. Motions inside the cloud, and motion of the cloud will broaden and shift the observed lines!

Some HI is in reasonably well defined clouds. Motions inside the cloud, and motion of the cloud will broaden and shift the observed lines! Some HI is in reasonably well defined clouds. Motions inside the cloud, and motion of the cloud will broaden and shift the observed lines Idealized 21cm spectra Example observed 21cm spectra HI densities

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

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

Chapter 10 The Interstellar Medium

Chapter 10 The Interstellar Medium Chapter 10 The Interstellar Medium Guidepost You have begun your study of the sun and other stars, but now it is time to study the thin gas and dust that drifts through space between the stars. This chapter

More information

Galaxies and the Universe. Our Galaxy - The Milky Way The Interstellar Medium

Galaxies and the Universe. Our Galaxy - The Milky Way The Interstellar Medium Galaxies and the Universe Our Galaxy - The Milky Way The Interstellar Medium Our view of the Milky Way The Radio Sky COBE Image of our Galaxy The Milky Way Galaxy - The Galaxy By Visual Observation

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

6. Interstellar Medium. Emission nebulae are diffuse patches of emission surrounding hot O and

6. Interstellar Medium. Emission nebulae are diffuse patches of emission surrounding hot O and 6-1 6. Interstellar Medium 6.1 Nebulae Emission nebulae are diffuse patches of emission surrounding hot O and early B-type stars. Gas is ionized and heated by radiation from the parent stars. In size,

More information

A World of Dust. Bare-Eye Nebula: Orion. Interstellar Medium

A World of Dust. Bare-Eye Nebula: Orion. Interstellar Medium Interstellar Medium Physics 113 Goderya Chapter(s): 10 Learning Outcomes: A World of Dust The space between the stars is not completely empty, but filled with very dilute gas and dust, producing some of

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

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

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

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

The Physics of the Interstellar Medium

The Physics of the Interstellar Medium The Physics of the Interstellar Medium Ulrike Heiter Contact: 471 5970 ulrike@astro.uu.se www.astro.uu.se Matter between stars Average distance between stars in solar neighbourhood: 1 pc = 3 x 1013 km,

More information

Astrophysical Quantities

Astrophysical Quantities Astr 8300 Resources Web page: http://www.astro.gsu.edu/~crenshaw/astr8300.html Electronic papers: http://adsabs.harvard.edu/abstract_service.html (ApJ, AJ, MNRAS, A&A, PASP, ARAA, etc.) General astronomy-type

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

Radio Observations of TeV and GeV emitting Supernova Remnants

Radio Observations of TeV and GeV emitting Supernova Remnants Radio Observations of TeV and GeV emitting Supernova Remnants Denis Leahy University of Calgary, Calgary, Alberta, Canada (collaborator Wenwu Tian, National Astronomical Observatories of China) outline

More information

Reminders! Observing Projects: Both due Monday. They will NOT be accepted late!!!

Reminders! Observing Projects: Both due Monday. They will NOT be accepted late!!! Reminders! Website: http://starsarestellar.blogspot.com/ Lectures 1-15 are available for download as study aids. Reading: You should have Chapters 1-14 read. Read Chapters 15-17 by the end of the week.

More information

The inverse process is recombination, and in equilibrium

The inverse process is recombination, and in equilibrium Section 4 Ionization equilibrium As we have discussed previously, UV photons will photoionize neutral hydrogen atoms if they have with hν > 13.6eV (= I H, the ionization potential for hydrogen). The excess

More information

Interstellar Astrophysics Summary notes: Part 2

Interstellar Astrophysics Summary notes: Part 2 Interstellar Astrophysics Summary notes: Part 2 Dr. Paul M. Woods The main reference source for this section of the course is Chapter 5 in the Dyson and Williams (The Physics of the Interstellar Medium)

More information

The Milky Way Galaxy

The Milky Way Galaxy 1/5/011 The Milky Way Galaxy Distribution of Globular Clusters around a Point in Sagittarius About 00 globular clusters are distributed in random directions around the center of our galaxy. 1 1/5/011 Structure

More information

Astrophysics of Gaseous Nebulae and Active Galactic Nuclei

Astrophysics of Gaseous Nebulae and Active Galactic Nuclei SECOND EDITION Astrophysics of Gaseous Nebulae and Active Galactic Nuclei Donald E. Osterbrock Lick Observatory, University of California, Santa Cruz Gary J. Ferland Department of Physics and Astronomy,

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

Stellar Life Cycle in Giant Galactic Nebula NGC edited by David L. Alles Western Washington University

Stellar Life Cycle in Giant Galactic Nebula NGC edited by David L. Alles Western Washington University Stellar Life Cycle in Giant Galactic Nebula NGC 3603 edited by David L. Alles Western Washington University e-mail: alles@biol.wwu.edu Introduction NGC 3603 is a giant HII region in the Carina spiral arm

More information

Astronomy 113. Dr. Joseph E. Pesce, Ph.D. Distances & the Milky Way. The Curtis View. Our Galaxy. The Shapley View 3/27/18

Astronomy 113. Dr. Joseph E. Pesce, Ph.D. Distances & the Milky Way. The Curtis View. Our Galaxy. The Shapley View 3/27/18 Astronomy 113 Dr. Joseph E. Pesce, Ph.D. Distances & the Milky Way 14-2 Historical Overview: the Curtis-Shapley Debate ³What is the size of our galaxy? ³What is the nature of spiral nebula? The Curtis

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. Distances & the Milky Way Historical Overview: the Curtis-Shapley Debate ³What is the size of our galaxy? ³What is the nature of spiral nebula? 14-2 ³Occurred in

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

Lecture 2: Introduction to stellar evolution and the interstellar medium. Stars and their evolution

Lecture 2: Introduction to stellar evolution and the interstellar medium. Stars and their evolution Lecture 2: Introduction to stellar evolution and the interstellar medium Stars and their evolution The Hertzsprung-Russell (HR) Diagram (Color-Magnitude Diagram) Apparent and Absolute Magnitudes; Dust

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

M.Phys., M.Math.Phys., M.Sc. MTP Radiative Processes in Astrophysics and High-Energy Astrophysics

M.Phys., M.Math.Phys., M.Sc. MTP Radiative Processes in Astrophysics and High-Energy Astrophysics M.Phys., M.Math.Phys., M.Sc. MTP Radiative Processes in Astrophysics and High-Energy Astrophysics Professor Garret Cotter garret.cotter@physics.ox.ac.uk Office 756 in the DWB & Exeter College Radiative

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

Chapter 19 Lecture. The Cosmic Perspective Seventh Edition. Our Galaxy Pearson Education, Inc.

Chapter 19 Lecture. The Cosmic Perspective Seventh Edition. Our Galaxy Pearson Education, Inc. Chapter 19 Lecture The Cosmic Perspective Seventh Edition Our Galaxy Our Galaxy 19.1 The Milky Way Revealed Our goals for learning: Where are we located within our galaxy? What does our galaxy look like?

More information

Effects of Massive Stars

Effects of Massive Stars Effects of Massive Stars Classical HII Regions Ultracompact HII Regions Stahler Palla: Sections 15.1, 15. HII Regions The salient characteristic of any massive star is its extreme energy output, much of

More information

ASTR2050 Spring Please turn in your homework now! In this class we will discuss the Interstellar Medium:

ASTR2050 Spring Please turn in your homework now! In this class we will discuss the Interstellar Medium: ASTR2050 Spring 2005 Lecture 10am 29 March 2005 Please turn in your homework now! In this class we will discuss the Interstellar Medium: Introduction: Dust and Gas Extinction and Reddening Physics of Dust

More information

Possible Extra Credit Option

Possible Extra Credit Option Possible Extra Credit Option Attend an advanced seminar on Astrophysics or Astronomy held by the Physics and Astronomy department. There are seminars held every 2:00 pm, Thursday, Room 190, Physics & Astronomy

More information

Astr 5465 Feb. 5, 2018 Kinematics of Nearby Stars

Astr 5465 Feb. 5, 2018 Kinematics of Nearby Stars Astr 5465 Feb. 5, 2018 Kinematics of Nearby Stars Properties of Nearby Stars Most in orbit with the Sun around Galactic Center Stellar Kinematics Reveal Groups of Stars with Common Space Motion (Moving

More information

Stellar Life Cycle in Giant Galactic Nebula NGC 3603

Stellar Life Cycle in Giant Galactic Nebula NGC 3603 Stellar Life Cycle in Giant Galactic Nebula NGC 3603 edited by David L. Alles Western Washington University e-mail: alles@biol.wwu.edu Last Updated 2009-11-20 Note: In PDF format most of the images in

More information

Chapter 19 Lecture. The Cosmic Perspective. Seventh Edition. Our Galaxy Pearson Education, Inc.

Chapter 19 Lecture. The Cosmic Perspective. Seventh Edition. Our Galaxy Pearson Education, Inc. Chapter 19 Lecture The Cosmic Perspective Seventh Edition Our Galaxy 19.1 The Milky Way Revealed Our goals for learning: Where are we located within our galaxy? What does our galaxy look like? How do stars

More information

Astrophysics of Gaseous Nebulae

Astrophysics of Gaseous Nebulae Astrophysics of Gaseous Nebulae Astrophysics of Gaseous Nebulae Bright Nebulae of M33 Ken Crawford (Rancho Del Sol Observatory) Potsdam University Dr. Lidia Oskinova lida@astro.physik.uni-potsdam.de HST

More information

Our goals for learning: 2014 Pearson Education, Inc. We see our galaxy edge-on. Primary features: disk, bulge, halo, globular clusters All-Sky View

Our goals for learning: 2014 Pearson Education, Inc. We see our galaxy edge-on. Primary features: disk, bulge, halo, globular clusters All-Sky View Our Galaxy Chapter 19 Lecture The Cosmic Perspective 19.1 The Milky Way Revealed What does our galaxy look like? What does our galaxy look like? How do stars orbit in our galaxy? Seventh Edition Our Galaxy

More information

The Interstellar Medium.

The Interstellar Medium. The Interstellar Medium http://apod.nasa.gov/apod/astropix.html THE INTERSTELLAR MEDIUM Total mass ~ 5 to 10 x 10 9 solar masses of about 5 10% of the mass of the Milky Way Galaxy interior to the sun s

More information

Lecture 30. The Galactic Center

Lecture 30. The Galactic Center Lecture 30 History of the Galaxy Populations and Enrichment Galactic Evolution Spiral Arms Galactic Types Apr 5, 2006 Astro 100 Lecture 30 1 The Galactic Center The nature of the center of the Galaxy is

More information

The Interstellar Medium

The Interstellar Medium THE INTERSTELLAR MEDIUM Total mass ~ 0.5 to 1 x 10 10 solar masses of about 5 10% of the mass of the Milky Way Galaxy interior to the sun s orbit The Interstellar http://apod.nasa.gov/apod/astropix.html

More information

A100 Exploring the Universe: The Milky Way as a Galaxy. Martin D. Weinberg UMass Astronomy

A100 Exploring the Universe: The Milky Way as a Galaxy. Martin D. Weinberg UMass Astronomy A100 Exploring the Universe: The Milky Way as a Galaxy Martin D. Weinberg UMass Astronomy astron100-mdw@courses.umass.edu November 12, 2014 Read: Chap 19 11/12/14 slide 1 Exam #2 Returned and posted tomorrow

More information

The distance modulus in the presence of absorption is given by

The distance modulus in the presence of absorption is given by Problem 4: An A0 main sequence star is observed at a distance of 100 pc through an interstellar dust cloud. Furthermore, it is observed with a color index B-V = 1.5. What is the apparent visual magnitude

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

ASTR 101 Introduction to Astronomy: Stars & Galaxies

ASTR 101 Introduction to Astronomy: Stars & Galaxies ASTR 101 Introduction to Astronomy: Stars & Galaxies If your clicker grade on BlackBoard is 0 and you have been in class, please send your clicker # to TA Cameron Clarke for checking The Milky Way Size

More information

View of the Galaxy from within. Lecture 12: Galaxies. Comparison to an external disk galaxy. Where do we lie in our Galaxy?

View of the Galaxy from within. Lecture 12: Galaxies. Comparison to an external disk galaxy. Where do we lie in our Galaxy? Lecture 12: Galaxies View of the Galaxy from within The Milky Way galaxy Rotation curves and dark matter External galaxies and the Hubble classification scheme Plotting the sky brightness in galactic coordinates,

More information

The Milky Way - Chapter 23

The Milky Way - Chapter 23 The Milky Way - Chapter 23 The Milky Way Galaxy A galaxy: huge collection of stars (10 7-10 13 ) and interstellar matter (gas & dust). Held together by gravity. Much bigger than any star cluster we have

More information

BUT, what happens when atoms, with electrons attached, are packed really close together? The electrons from the neighboring atoms can have a small

BUT, what happens when atoms, with electrons attached, are packed really close together? The electrons from the neighboring atoms can have a small Quiz #5 There are two stars, star A and star B. Star A is approaching the Earth at 100 km/s and Star B is moving away from the Earth at 200 km/s. Compare the Doppler shift for these two stars by explaining

More information

23 Astrophysics 23.5 Ionization of the Interstellar Gas near a Star

23 Astrophysics 23.5 Ionization of the Interstellar Gas near a Star 23 Astrophysics 23.5 Ionization of the Interstellar Gas near a Star (8 units) No knowledge of Astrophysics is assumed or required: all relevant equations are defined and explained in the project itself.

More information

29:50 Stars, Galaxies, and the Universe Second Hour Exam November 10, 2010 Form A

29:50 Stars, Galaxies, and the Universe Second Hour Exam November 10, 2010 Form A 29:50 Stars, Galaxies, and the Universe Second Hour Exam November 10, 2010 Form A There are 20 questions (Note: There will be 32 on the real thing). Read each question and all of the choices before choosing.

More information

Our View of the Milky Way. 23. The Milky Way Galaxy

Our View of the Milky Way. 23. The Milky Way Galaxy 23. The Milky Way Galaxy The Sun s location in the Milky Way galaxy Nonvisible Milky Way galaxy observations The Milky Way has spiral arms Dark matter in the Milky Way galaxy Density waves produce spiral

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

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

Components of Galaxies Gas The Importance of Gas

Components of Galaxies Gas The Importance of Gas Components of Galaxies Gas The Importance of Gas Fuel for star formation (H 2 ) Tracer of galaxy kinematics/mass (HI) Tracer of dynamical history of interaction between galaxies (HI) The Two-Level Atom

More information

telescopes resolve it into many faint (i.e. distant) stars What does it tell us?

telescopes resolve it into many faint (i.e. distant) stars What does it tell us? The Milky Way From a dark site the Milky Way can be seen as a broad band across the sky What is it? telescopes resolve it into many faint (i.e. distant) stars What does it tell us? that we live in a spiral

More information

An Introduction to Galaxies and Cosmology

An Introduction to Galaxies and Cosmology An Introduction to Galaxies and Cosmology 1.1 Introduction Milky Way (our galaxy - Galaxy) Fig. 1.1 A photograph of one hemisphere of the night sky. (D.di Cicco, Sky Publishing Corp.) 1011 stars 1012

More information

INTRODUCTION TO SPACE

INTRODUCTION TO SPACE INTRODUCTION TO SPACE 25.3.2019 The Galaxy II: Stars: Classification and evolution Various types of stars Interstellar matter: dust, gas Dark matter ELEC-E4530 Radio astronomy: the Sun, pulsars, microquasars,

More information

Supernovae. Supernova basics Supernova types Light Curves SN Spectra after explosion Supernova Remnants (SNRs) Collisional Ionization

Supernovae. Supernova basics Supernova types Light Curves SN Spectra after explosion Supernova Remnants (SNRs) Collisional Ionization Supernovae Supernova basics Supernova types Light Curves SN Spectra after explosion Supernova Remnants (SNRs) Collisional Ionization 1 Supernova Basics Supernova (SN) explosions in our Galaxy and others

More information

a few more introductory subjects : equilib. vs non-equil. ISM sources and sinks : matter replenishment, and exhaustion Galactic Energetics

a few more introductory subjects : equilib. vs non-equil. ISM sources and sinks : matter replenishment, and exhaustion Galactic Energetics Today : a few more introductory subjects : equilib. vs non-equil. ISM sources and sinks : matter replenishment, and exhaustion Galactic Energetics photo-ionization of HII assoc. w/ OB stars ionization

More information

Class #4 11 September 2008

Class #4 11 September 2008 Class #4 11 September 2008 Review Stellar evolution/nucleosynthesis/h-r diagrams Phases of the Interstellar Medium The Hydrogen Atom H-R diagram for 47 Tuc Evolution+nucleosynt hesis each box is a different

More information

Physics and Chemistry of the Interstellar Medium

Physics and Chemistry of the Interstellar Medium Physics and Chemistry of the Interstellar Medium Sun Kwok The University of Hong Kong UNIVERSITY SCIENCE BOOKS Sausalito, California * Preface xi The Interstellar Medium.1.1 States of Matter in the ISM

More information

29:50 Stars, Galaxies, and the Universe Final Exam December 13, 2010 Form A

29:50 Stars, Galaxies, and the Universe Final Exam December 13, 2010 Form A 29:50 Stars, Galaxies, and the Universe Final Exam December 13, 2010 Form A There are 40 questions. Read each question and all of the choices before choosing. Budget your time. No whining. Walk with Ursus!

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

An Introduction to Radio Astronomy

An Introduction to Radio Astronomy An Introduction to Radio Astronomy Bernard F. Burke Massachusetts Institute of Technology and Francis Graham-Smith Jodrell Bank, University of Manchester CAMBRIDGE UNIVERSITY PRESS Contents Preface Acknowledgements

More information

Interstellar Medium by Eye

Interstellar Medium by Eye Interstellar Medium by Eye Nebula Latin for cloud = cloud of interstellar gas & dust Wide angle: Milky Way Summer Triangle (right) α&β Centauri, Coal Sack Southern Cross (below) Dust-Found in the Plane

More information

LECTURE 1: Introduction to Galaxies. The Milky Way on a clear night

LECTURE 1: Introduction to Galaxies. The Milky Way on a clear night LECTURE 1: Introduction to Galaxies The Milky Way on a clear night VISIBLE COMPONENTS OF THE MILKY WAY Our Sun is located 28,000 light years (8.58 kiloparsecs from the center of our Galaxy) in the Orion

More information

HII regions. Massive (hot) stars produce large numbers of ionizing photons (energy above 13.6 ev) which ionize hydrogen in the vicinity.

HII regions. Massive (hot) stars produce large numbers of ionizing photons (energy above 13.6 ev) which ionize hydrogen in the vicinity. HII regions Massive (hot) stars produce large numbers of ionizing photons (energy above 13.6 ev) which ionize hydrogen in the vicinity. Detailed nebular structure depends on density distribution of surrounding

More information

Astronomy 114. Lecture 27: The Galaxy. Martin D. Weinberg. UMass/Astronomy Department

Astronomy 114. Lecture 27: The Galaxy. Martin D. Weinberg. UMass/Astronomy Department Astronomy 114 Lecture 27: The Galaxy Martin D. Weinberg weinberg@astro.umass.edu UMass/Astronomy Department A114: Lecture 27 18 Apr 2007 Read: Ch. 25,26 Astronomy 114 1/23 Announcements Quiz #2: we re

More information

Photoionization Modelling of H II Region for Oxygen Ions

Photoionization Modelling of H II Region for Oxygen Ions Journal of Materials Science and Chemical Engineering, 2015, 3, 7-16 Published Online April 2015 in SciRes. http://www.scirp.org/journal/msce http://dx.doi.org/10.4236/msce.2015.34002 Photoionization Modelling

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

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

Supernovae. Supernova basics Supernova types Light Curves SN Spectra after explosion Supernova Remnants (SNRs) Collisional Ionization

Supernovae. Supernova basics Supernova types Light Curves SN Spectra after explosion Supernova Remnants (SNRs) Collisional Ionization Supernovae Supernova basics Supernova types Light Curves SN Spectra after explosion Supernova Remnants (SNRs) Collisional Ionization 1 Supernova Basics Supernova (SN) explosions in our Galaxy and others

More information

Diffuse Ultraviolet Emission in Galaxies

Diffuse Ultraviolet Emission in Galaxies National Aeronautics and Space Administration Diffuse Ultraviolet Emission in Galaxies Anne Pellerin and Martin J. Meyer Taken from: Produced by NASA Goddard Space Flight Center and Space Telescope Science

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

ASTRO 310: Galac/c & Extragalac/c Astronomy Prof. Jeff Kenney. Class 7 Sept 19, 2018 The Milky Way Galaxy: Gas: HII Regions

ASTRO 310: Galac/c & Extragalac/c Astronomy Prof. Jeff Kenney. Class 7 Sept 19, 2018 The Milky Way Galaxy: Gas: HII Regions ASTRO 310: Galac/c & Extragalac/c Astronomy Prof. Jeff Kenney Class 7 Sept 19, 2018 The Milky Way Galaxy: Gas: HII Regions importance of HII regions one of main ISM phases great example for understanding

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

Lecture 25 The Milky Way Galaxy November 29, 2017

Lecture 25 The Milky Way Galaxy November 29, 2017 Lecture 25 The Milky Way Galaxy November 29, 2017 1 2 Size of the Universe The Milky Way galaxy is very much larger than the solar system Powers of Ten interactive applet 3 Galaxies Large collections of

More information

Dark Matter. ASTR 333/433 Spring Today Stars & Gas. essentials about stuff we can see. First Homework on-line Due Feb. 4

Dark Matter. ASTR 333/433 Spring Today Stars & Gas. essentials about stuff we can see. First Homework on-line Due Feb. 4 Dark Matter ASTR 333/433 Spring 2016 Today Stars & Gas essentials about stuff we can see First Homework on-line Due Feb. 4 Galaxies are made of stars - D. Silva (1990) private communication Stars Majority

More information

Chapter 15 The Milky Way Galaxy. The Milky Way

Chapter 15 The Milky Way Galaxy. The Milky Way Chapter 15 The Milky Way Galaxy The Milky Way Almost everything we see in the night sky belongs to the Milky Way We see most of the Milky Way as a faint band of light across the sky From the outside, our

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

The Milky Way. Overview: Number of Stars Mass Shape Size Age Sun s location. First ideas about MW structure. Wide-angle photo of the Milky Way

The Milky Way. Overview: Number of Stars Mass Shape Size Age Sun s location. First ideas about MW structure. Wide-angle photo of the Milky Way Figure 70.01 The Milky Way Wide-angle photo of the Milky Way Overview: Number of Stars Mass Shape Size Age Sun s location First ideas about MW structure Figure 70.03 Shapely (~1900): The system of globular

More information

The Universe o. Galaxies. The Universe of. Galaxies. Ajit Kembhavi IUCAA

The Universe o. Galaxies. The Universe of. Galaxies. Ajit Kembhavi IUCAA Hello! The Universe of Galaxies The Universe o Galaxies Ajit Kembhavi IUCAA Galaxies: Stars: ~10 11 Mass: ~10 11 M Sun Contain stars, gas and dust, possibly a supermassive black hole at the centre. Much

More information

The Galaxy. (The Milky Way Galaxy)

The Galaxy. (The Milky Way Galaxy) The Galaxy (The Milky Way Galaxy) Which is a picture of the Milky Way? A A is what we see from Earth inside the Milky Way while B is what the Milky Way might look like if we were far away looking back

More information

The Milky Way Galaxy. Some thoughts. How big is it? What does it look like? How did it end up this way? What is it made up of?

The Milky Way Galaxy. Some thoughts. How big is it? What does it look like? How did it end up this way? What is it made up of? Some thoughts The Milky Way Galaxy How big is it? What does it look like? How did it end up this way? What is it made up of? Does it change 2 3 4 5 This is not a constant zoom The Milky Way Almost everything

More information

Stellar Populations: Resolved vs. unresolved

Stellar Populations: Resolved vs. unresolved Outline Stellar Populations: Resolved vs. unresolved Individual stars can be analyzed Applicable for Milky Way star clusters and the most nearby galaxies Integrated spectroscopy / photometry only The most

More information

Chapter 4. Spectroscopy. Dr. Tariq Al-Abdullah

Chapter 4. Spectroscopy. Dr. Tariq Al-Abdullah Chapter 4 Spectroscopy Dr. Tariq Al-Abdullah Learning Goals: 4.1 Spectral Lines 4.2 Atoms and Radiation 4.3 Formation of the Spectral Lines 4.4 Molecules 4.5 Spectral Line Analysis 2 DR. T. AL-ABDULLAH

More information

Photoionized Gas Ionization Equilibrium

Photoionized Gas Ionization Equilibrium Photoionized Gas Ionization Equilibrium Ionization Recombination H nebulae - case A and B Strömgren spheres H + He nebulae Heavy elements, dielectronic recombination Ionization structure 1 Ionization Equilibrium

More information

Our Galaxy. We are located in the disk of our galaxy and this is why the disk appears as a band of stars across the sky.

Our Galaxy. We are located in the disk of our galaxy and this is why the disk appears as a band of stars across the sky. Our Galaxy Our Galaxy We are located in the disk of our galaxy and this is why the disk appears as a band of stars across the sky. Early attempts to locate our solar system produced erroneous results.

More information

Results better than Quiz 5, back to normal Distribution not ready yet, sorry Correct up to 4 questions, due Monday, Apr. 26

Results better than Quiz 5, back to normal Distribution not ready yet, sorry Correct up to 4 questions, due Monday, Apr. 26 Brooks observing April 19-22: 9:00 PM to at least 10:15 PM Tonight is a go! April 26-29: 9:30 PM to at least 10:45 PM Regular Friday evening public observing after planetarium shows also an option Begins

More information

Light and Atoms. ASTR 1120 General Astronomy: Stars & Galaxies. ASTR 1120 General Astronomy: Stars & Galaxies !ATH REVIEW: #AST CLASS: "OMEWORK #1

Light and Atoms. ASTR 1120 General Astronomy: Stars & Galaxies. ASTR 1120 General Astronomy: Stars & Galaxies !ATH REVIEW: #AST CLASS: OMEWORK #1 ASTR 1120 General Astronomy: Stars & Galaxies!ATH REVIEW: Tonight, 5-6pm, in RAMY N1B23 "OMEWORK #1 -Due THU, Sept. 10, by 5pm, on Mastering Astronomy CLASS RECORDED STARTED - INFO WILL BE POSTED on CULEARN

More information

Neutron Stars. Neutron Stars and Black Holes. The Crab Pulsar. Discovery of Pulsars. The Crab Pulsar. Light curves of the Crab Pulsar.

Neutron Stars. Neutron Stars and Black Holes. The Crab Pulsar. Discovery of Pulsars. The Crab Pulsar. Light curves of the Crab Pulsar. Chapter 11: Neutron Stars and Black Holes A supernova explosion of an M > 8 M sun star blows away its outer layers. Neutron Stars The central core will collapse into a compact object of ~ a few M sun.

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

Ionization of the Local Interstellar Cavity by Hot White Dwarfs

Ionization of the Local Interstellar Cavity by Hot White Dwarfs Ionization of the Local Interstellar Cavity by Hot White Dwarfs Barry Y. Welsh Experimental Astrophysics Group Space Sciences Lab, UC Berkeley Thanks to: Martin Barstow, Nathan Dickinson (Univ of Leicester)

More information

Exam #3. Median: 83.8% High: 100% If you d like to see/discuss your exam, come to my office hours, or make an appointment.

Exam #3. Median: 83.8% High: 100% If you d like to see/discuss your exam, come to my office hours, or make an appointment. Exam #3 Average: 80.1% Median: 83.8% High: 100% Scores available on Blackboard If you d like to see/discuss your exam, come to my office hours, or make an appointment. Exam #3 The Sun is made of A) all

More information

Notes on Photoionized Regions Wednesday, January 12, 2011

Notes on Photoionized Regions Wednesday, January 12, 2011 Notes on Photoionized Regions Wednesday, January 12, 2011 CONTENTS: 1. Introduction 2. Hydrogen Nebulae A. Ionization equations B. Recombination coefficients and cross sections C. Structure of the hydrogen

More information

Three Major Components

Three Major Components The Milky Way Three Major Components Bulge young and old stars Disk young stars located in spiral arms Halo oldest stars and globular clusters Components are chemically, kinematically, and spatially distinct

More information