Harvard Astronomy 201b

Our Jointly-Edited Online “Book”

This “book” accompanies the Harvard University graduate course Astronomy 201b, “The Interstellar Medium and Star Formation.” The first incarnation was created in 2011 by Prof. Alyssa Goodman, Teaching Fellow Chris Beaumont, and the 21 Harvard graduate students who took the course at that time. The “book” will continue to evolve throughout Spring 2013 as student contributions from this new instance of the course are added.

Links at the top of each section (in orange) are slides and notes from this year (2013), sorted by date. They will be posted within one day of the class date. Links in red are transcriptions of Alyssa Goodman’s notes, originally from 2011 and updated throughout the semester as we discuss each topic. Links in green are student contributions from 2011. Links in blue are transcriptions from guest lecturers. Links in violet are the class handouts and weblinks which can (hopefully!) be posted here without copyright violation.

Student contributions from 2011 are shown in dark green.  Online modules developed by the AY201b students at Harvard in 2013 are listed here.

NOTE: Lecture notes, to be used for reference, from AY208 v.Y2K are linked here in PDF format. The scanned handwritten notes corresponding to these pages are found here.

The following schedule has been updated to reflect 2013 dates. NOTE: Subject to change as the semester evolves!

I. Introduction

(1) Jan. 29: Introduction and Course Plan  The Stromgren Sphere

(2) Jan. 31: Intro to the Milky Way’s ISM • How do we know there is an ISM? • A sense of scale • ISM density in the Milky Way • Density of the Intergalactic Medium (IGM) • Michael Richmond’s Page on Dust • reading: Draine Ch. 1

(3) Feb. 5: Intro to the Milky Way’s ISM, continued • Composition of the ISM • Topology of the ISM • Energy Density in the ISM

(4) Feb. 7: Virial Equilibrium and Larson’s Laws • Velocities in the ISM • The Virial Theorem • reading: Draine Ch. 35 (Fluid Dynamics), Appendix J (Virial Theorem)

additional material: Angular vs. Linear sizes  Molecular cloud properties  Interstellar cloud properties

II. Kinetic Equilibrium and Radiative Processes

(5) Feb. 12:   The sound speedHydrogen slang • Chemistry • Bowers and Deeming excerpt on the Saha Equation

(6) Feb 14:  Measuring ISM states

(7) Feb. 26: Introduction to radiative processes • Thermodynamic Equilibrium • Spitzer Notation • The Saha Equation • Important properties of Local Thermodynamic Equilibrium • Definitions of Temperature • reading: Radiation Bookeeping; Draine Ch. 3

(8) Feb. 28: Excitation Processes: Collisions • Neutral-Neutral Collisions • Ion-Neutral Collisions • reading: Draine Ch. 2

additional material: Radiative Transfer  Collisonal Excitation  Recombination • History of Saha  Jonathan Williams’ page on measuring dust mass   NRAO: Brightness and Flux Density  Book Chapter: Interstellar Extinction and Scattering

III. The ISM of the Milky Way

(9) March 5: All About Dust

(10) March 7: Considering a Multi-phase ISM • reading: Draine Ch. 39

(11) March 12: NRAO: Molecular Spectra • Atomic Energy Level Diagram

(12) March 14: HI and CO • Perspectives on PDRs (Wolfire)

additional material: The Cold ISM • Cold ISM (Ian Czekala) • CO as a coolant (Katherine Rosenfeld) • The Hot ISM (Vicente Rodriguez) • X-Ray Absorption by the ISM (Ragnhild Lunnan) • The Leiden Atomic Molecular Database • Myers et al. Dense Cores in Dark Clouds VI: Shapes

IV. Molecular Clouds and Star Formation

(13) March 26: Introductory Remarks • Basic properties of GMCs • The Jeans Mass • Collapse Timescale • The Jeans Swindle • Some thoughts on Jeans scales • Larson’s legacy

(14) March 28: Numerical Star Formation Simulations (Stella Offner)

(15) April 2: COMPLETE steps of star formation

additional material: GMC Formation and Spiral Spurs •Magnetic Fields on Galaxy Scales  • SEDs of young stars • Instabilities • Larson’s Legacy • Spitzer’s Gravitational Collapse of a Sphere

V. Interactions of photons and stellar winds with the ISM

(16) April 4: Data cubes and outflows

(17) April 9: Shocks • Introduction to Shocks • Rankine-Hugoniot Jump Conditions • Jonathan Williams’s page on shocks • Shock Dejargonification • Wikipedia page on R-H Jump Conditions • Shock Examples

(18) April 11: Magnetic fields in the ISM

(19) April 16: Effects of massive stars on the ISM

(20) April 18: Young stars, disks, & ouflows

additional material:  •The Orion Bar •Diagnostics of HII regions • Outflows in Star Forming Regions (Hector Arce)  • Shock Viscosity  • Introduction to Instabilities • The Rayleigh-Taylor Instability • Ionization fronts • HII region growth • Stellar Winds • Disk Structure • The Magnetorotational instability • Does the CMF come from the IMF? • Supernova Remnants in Theory and Practice   • Path of photons in an HII region

VI. Disks and Planet Formation

(21) April 23: •Disks in the context of star and planet formation

additional material: How do planets form? Observing Disks: Spectral Energy Distributions and how they are used •The meaning and significance of the “Snow Line” in disks •Formation of Planetesimals

VII. The ISM of Other Galaxies and the Intergalactic Medium

(22) April 25: Gas beyond the Milky Way

additional material: Key (Open) Questions •The High Redshift ISM •The SINGS Survey •The Magellanic Stream •The ISM & Star Formation at very high redshift •Density, Temperature, and Magnetic Field of the very early universe

Special Topics

•The Role of dark matter in extragalactic star formationFuture Instruments •Concluding Comments / Special Topics


“Star Formation in Molecular Clouds” by Mark Krumholz, 2011. (astro-ph)

“The Formation of Stars” by Steve Stahler & Francesco Palla, 2004 (Google Books)

“Protostars and Planets V” an edited collection of reviews, 2007 (Google Books)


Chris Faesi: cfaesi[at]cfa.harvard.edu

Nathan Sanders: nsanders[at]cfa.harvard.edu

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