Lecture Syllabus & Notes

• Introduction to topics to be covered
• Challenge of vast range of scales, in space and time
• We are but one star of several hundred billion in our galaxy
• And there are billions of galaxies.....
• Scientific method: what it is all about
• Detailed course syllabus passed out -- also posted on website here

Lecture 2: Astronomy as a science; light as waves (Wed, Jan 12)

• Nature of astronomy as a science
• Scientific method
• Light as waves
• Homework Set #1 distributed
• Observatory Night #1 tomorrow night, Thur 13 Jan 7pm+, by sign-up

Lecture 3: Atoms and light I (Fri, Jan 14)

• Four fundamental forces
• Atoms: nucleus plus electrons in (distant) orbits
• Coupling of atoms and light
• Photons absorbed/emitted as electrons pop from one orbit to another
• Special colors of light (spectral lines) with each element (demo)

Lecture 4: Atoms and light II (Wed, Jan 19)

• Coupling of atoms and light
• Kirchoff's "laws"
• Observatory Night #2 tomorrow night, Thur 20 Jan 7pm+

Lecture 5: Telescopes and issues of observing I (Fri, Jan 21)

• Doppler effect
• Principles common to our eyes, cameras, telescopes
• Reflectors prevail over refractors for astronomy
• Conserving angular momentum, useful to point space telescopes
• Homework Set #2 on telescopes distributed

Lecture 6: Telescopes II (Mon, Jan 24)

• Effects of our atmosphere on light
• Light pollution, twinkling by turbulence, absorption by atmosphere
• What light gets through, what does not
• How do we observe from space

Lecture 7: `City of Stars', planetarium show (Wed, Jan 26)

• Survey of our galaxy, the Milky Way
• Objects and clusters within it
• How stellar evolution is proceeding

Lecture 8: The Sun in overview (Fri, Jan 28)

• Radio telescopes and x-ray telescopes look rather different
• Overview of our nearest star, the Sun
• Why is it round?
• Equilibrium between pull of gravity and push of pressure
• Fusion reactions convert H to He, keep the center very hot
• Homework Set #3 distributed; HW #1 returned graded, plus answer sheet

Lecture 9: Powering the Sun (Mon, Jan 31)

• Fusion reactions (p-p chain) convert H to He, center very hot
• Workings of the solar thermostat
• Puzzle of the neutrinos

Lecture 10: The dynamic Sun (Wed, 2 Feb)

• Neutrino subtleties
• Regions of the Sun and their function: core, radiative zone, convective envelope, atmosphere
• How solar sound (helioseismology) is used to image the deep interior

Lecture 11: Helioseismology and solar magnetism (Fri, 4 Feb)

• What helioseismology reveals about interior flows and structures
• Striking solar differential rotation, flows of solar surface weather (SSW)
• Solar magnetism, solar wind and northern lights
• The solar magnetic cycle involving sunspots and variable activity
• Solar magnetic fields and their 11-year cycles

Lecture 12: Solar magnetism II (Mon, 7 Feb)

• Nature of sunspots, loops, flares
• Hot turbulent plasma can serve as magnetic dynamo
• Operation of solar dynamo in the deep interior

Lecture 13: Solar dynamo; measuring other stars (Wed, 9 Feb)

• Modelling solar convection and the dynamo
• What can we measure in other stars: brightness, position, spectrum
• Stellar luminosity and apparent brightness
• Distance from stellar parallax

Lecture 14: FIRST MID-TERM EXAM, in-class (Fri, 11 Feb)

Lecture 15: Stars: linking temperature and spectral classes (Mon, 14 Feb)

• Devising a classification for stars based on absorption features in spectra (O,B,A,F,G,K,M)
• Why surface temperature of star and spectral classification (O,B,A ..) are closely linked
• Saha equation used to predict spectral line strengths with temperature
• Luminosity classes by width of spectral lines (I to V)
• First look at Hertzsprung-Russell (H-R) diagram

Lecture 16: Stars: magnitudes and binaries (Wed, 16 Feb)

• Measuring brightness of stars: strange system of magnitudes
• Apparent vs absolute magnitude (luminosity) requires knowing distance
• Determine radii of stars, if know luminosity and temperature
• Binary stars in four flavors: both common and crucial to measure masses

Lecture 17: Stars: stellar masses and life on main sequence (Fri, 18 Feb)

• Estimating stellar masses from binary star data
• Where different stars lie on H-R diagram, and why in overview
• `Observed' mass-luminosity relation for main sequence stars
• Estimate how lifetimes on main sequence vary with stellar mass, and why
• Difference between force and pressure: bed of nails

Lecture 18: Stars: massive stars and star clusters (Mon, 21 Feb)

• Estimates of lifetimes on main sequence: more massive stars have very short lives!
• C-N-O fusion cycle powers the more massive stars
• Nuclear fusion reactions increase very rapidly with temperature: thus massive stars really pour out the energy!
• All main sequence stars
• Using star clusters to test ideas of lifetimes on main sequence

Lecture 19: Low-mass stars: life after main sequence (Wed, 23 Feb)

• Life after main sequence for low-mass stars -- becoming a red giant
• Red giant star, with H shell burning, has shrinking inert He core
• Degenerate matter has no thermostat, such as red giant's core
• Helium flash in core (triple-alpha burning of He) removes degeneracy
• Burning He in core (horizontal branch)
• Red supergiant phase (with double-shell burning of H and He)

Lecture 20: `Birth of Stars', planetarium show, with Ben Brown at helm (Fri, 25 Feb)

• Star birth -- how stars are assembled out of cold molecular clouds
• Beautiful emergence of stars from dusty cocoons
• Disks and jets around stars being formed

Lecture 21: Final stages in life of low-mass stars (Mon, 28 Feb)

• Red supergiant phase (double-shell burning of H and He)
• Planetary nebula involves shells `puffed off' from supergiant
• Properties of white dwarf star, as end of low-mass star
• Evolution of massive stars through giant and supergiant phases
• Fusion burning by He-capture of C, N, O .. in core and surrounding shells, like layers of onion: iron is the end of line!

Lecture 22: Massive star evolution: supernovae, SN remnants, neutron stars (Wed, 2 Mar)

• Fusion burning by He-capture of C, N, O .. in core and surrounding shells, like layers of onion: iron is the end of line!
• With enough core mass of iron, electron degeneracy can no longer support the star: `core collapse' supernova explosion
• Mass exchange by Roche lobe overflow in binary system: Algol paradox
• Supernovae (SN) can create neutron stars, formed from their collapsed iron cores
• SN explosion leads to nucleosynthesis, making all elements in universe heavier than iron

Lecture 23: Pulsars: discovery of neutron stars (Fri, 4 Mar)

• We are largely built out of recycled stellar material, at least 4.5 BY old!
• Discovery of radio pulses from unknown source, with very steady beat!
• Pulsars: rapidly rotating neutron stars with fierce magnetic fields
• Synchrotron radiation is source of intense light beamed by pulsars
• These `lighthouses in the sky' gradually slow down, using rotational energy to power the beams
• How mass transfer onto a neutron star in a binary system can spin it up
• Crab nebula supernova (4 July 1054) and pulsar show stunning behavior in Chandra and Hubble movies

Lecture 24: Supernova remnants and pulsars, fancy mass exchange in binaries (Mon, 7 Mar)

• Binary mass transfer onto white dwarfs can yield recurrent novae, or even detonate entire star (fusion of carbon) in supernova explosion
• Such `white dwarf supernovae' are superb bright reference `candles'
• SN detected in other galaxies can provide measures of vast distances
• Hot accretion disks always formed around objects on receiving end of binary mass transfer
• Similar mass tranfer onto neutron stars, with helium flash burning, may explain x-ray bursters
• Which supernova remnants (SNRs) contain pulsars, and if not, why not

Lecture 25: Relativity: effects of strong gravity or moving fast, black holes (Wed, 9 Mar)

• Einstein argued space and time are not distinct if speed of light is constant for all observers: thus need 4-dimensional `spacetime'
• Time slowed down by moving fast or experiencing strong gravity
• Strong gravity can seemingly bend light and redshift its frequency
• Warping of space and time by gravity
• Escape cones for light close at the `event horizon' around black holes, at a `Schwarzschild radius'
• Just three numbers describe a black hole: mass, electric charge, angular momentum
• Ergosphere: a spinning black hole drags nearby spacetime along

Lecture 26: SECOND MID-TERM EXAM, in-class (Fri, 11 Mar)

Lecture 27: Black holes, and overview of our Milky Way Galaxy (Mon, 14 Mar)

• How to detect a black hole
• Cygnus X-1 fine candidate for revealing a black hole in binary system
• The very strange object SS433, likely binary mass flow onto black hole that sends out precessing relativistic beams
• Gamma Ray Bursts (GRBs), vastly energetic sources that may be hypernova explosions in very distant galaxies
• Supermassive black holes, near centers of galaxies
• Milky Way: spiral galaxy with thin disk, bulge and halo
• Since stars and gas are always moving, inspires the galaxy song `The Galaxy / Lighten Up'

Lecture 28: Rotation curve and spiral making in Milky Way (Wed, 16 Mar)

• Milky Way (MW): spiral galaxy with thin disk, bulge and halo
• Motion of stars in galaxy: disk stars in nearly circular motion, halo and bulge stars in swooping orbits that dive through disk
• Look at how spiral patterns are made in the disks of galaxies, including our own
• `Density waves' in disk explain how spiral patterns are built
• Examine the rotation curve of our galaxy, and the unseen mass (dark matter) that it implies
• MW rotation curve of disk stars is flat at large radii from galactic center, indicating presence of `dark matter', probably in big spherical halo

Lecture 29: Star-gas-star recycling and the interstellar medium (Fri, 18 Mar)

• Inventory of our Milky Way galaxy: stars, gas, dust
• Interstellar medium (ISM), or stuff between the stars: its various components visited
• Some of the gas is very hot (from supernovae bubbles)
• Superbubbles blown by multiple supernovae, can even burst out of galactic disk
• Some of the gas is warm (emission nebulae near hot stars)
• Some is cold (molecular clouds), sites of star birth
• Dust is semi-warm, and can both absorb light and redden it, confusing distance estimates and blocking objects from view at visible wavelengths

Lecture 30: Spiral structure in MW galaxy, central black hole (Mon, 28 Mar)

• Revisit density waves (stellar traffic jams) in yielding spiral patterns in the disk
• Radio observations with 21 cm line of neutral hydrogen help reveal spiral structure in MW disk
• Spiral patterns outlined by bright O & B star associations, with vigourous star birth occurring in spiral arms
• Big mystery resolved: center of our galaxy contains 3 million solar mass black hole

Lecture 31: Universe of galaxies (Wed, 30 Mar)

• Classifying galaxies by appearance and shape: spirals, barred spirals, ellipticals, irregulars (Hubble's `tuning fork')
• What sample galaxies look like, and where found
• Big picture of universe: network of galaxy clusters and superclusters, with about 100 billion galaxies in all
• Our local group of galaxies: Andromeda, Triangulum and Milky Way are the heavyweights, then LMC and SMC, plus small ones, about 21 in all
• Cepheid variable stars provide a very important way to measure distance
• Edwin Hubble shows in 1924, using Cepheid variables, that Andromeda lies way outside of Milky Way -- there are other island universes!

Lecture 32: Discovery of expanding universe (Fri, 1 Apr)

• Edwin Hubble busily measures redshifts of many galaxies, announcing in 1929 that redshifts of galaxies appear to increase with distance from us!
• Such blockbuster news suggests that we are in an expanding universe!
• Hubble's Law and what it means

Lecture 33: Cosmic distances (Mon, 4 Apr)

• Measuring cosmic distances is a big challenge: identify `standard candles'
• Parallax, main-sequence fitting, Cepheid variables, white dwarf supernovae, and the Tully-Fisher relation each provide ways to estimate increasingly greater distances
• Distance ladder using overlapping standard candles
• Knowing the redshift of an object, can use Hubble's Law itself, once calibrated, for estimating biggest distances (or `lookback time')
• Most mapping of 3-D structure of galaxy clusters and superclusters thus accomplished using Hubble's Law

Lecture 34: Class meets in Fiske Planetarium: `Supernovae', special planetarium show given by Dick McCray (Wed, 6 Apr).

Lecture 35: Galaxy evolution: building spirals and colliding them (Fri, 8 Apr)

• Steps in forming a spiral galaxy, and in making ellipticals
• Birth of galaxies in clusters (few if any are born alone)
• Collisions or `interactions' between galaxies must be common
• Simulations of colliding galaxies yield bridges and tails, many of which are observed
• Modelling the `Mice" and the `Antennae' as interacting galaxies
• Andromeda galaxy (M31) is headed in our direction!

Lecture 36: Active galaxies: starburst, quasars, radio galaxies (Mon, 11 Apr)

• Messages from galaxy interactions (collisions): must be common early in dense clusters; spiral galaxies can tumble together to form elliptical galaxy; vastly increased star birth (starburst); rapid feeding of massive black hole (quasars and radio galaxies)
• Quasars - how discovered at large redshifts through bright emission lines of hydrogen
• Lyman alpha forest of absorption lines seen in spectra of quasars
• Model of `active galaxies': accretion disk around supermassive black hole, particle beams on axis of spinning disk form jets
• Synchrotron emission from jets can explain beams, seen also as great `radio tails'

Lecture 37: Supermassive black holes and dark matter (Wed, 13 Apr)

• Relativistic redshifts for objects (quasars) at large Z
• Evidence for supermassive black holes at centers of active galaxies, by observing accretion disks
• Absorption lines (`Lyman alpha forest') in quasar spectra reveal protogalactic clouds
• Case for dark matter as huge surrounding halo to spiral galaxy: flat rotation curves
• Galaxy clusters reveal dark matter in three ways: large random velocities of member galaxies, hot x-ray emitting gas in cluster, gravitational lensing

Lecture 38: THIRD MID-TERM EXAM, in-class (Fri, 15 Apr)

Lecture 39: Glow from early universe (CMB) and fates of universe (Mon, 18 Apr)

• Various predictions about universes from General Theory of Relativity (GTR)
• Cosmic microwave background (CMB) and its implications for `big bang' beginning
• Dark matter and fates of universe
• Three choices for fate of universe: coasting (open), critical (flat), recollapsing (closed)

Lecture 40: Class meets in Fiske Planetarium: `Dark Matter', special planetarium show created by Erica Ellingson given by Ben Brown (Wed, 20 Apr).

Lecture 42: Dark matter and gravitational lensing (Fri, 22 Apr)

• Gravitational lensing by clusters
• Ten times more dark matter than ordinary `baryonic' matter
• Dark matter: MACHOs or WIMPs, or neither?
• Cosmological models of universe, first look

Lecture 42: Beginning of time in the very early universe (Mon, 25 Apr)

• New twist on expansion: white dwarf supernovae suggest acceleration of universe from its earlier slowing down
• `Dark energy' invented to give outward push to expansion of universe, to counteract the inward pull of gravity slowing it down
• Dark energy 73%, cold dark matter 23%, ordinary (baryonic) matter 4%
• Gamow led the way with calculating big bang and which elements would be produced - looking at first 3 minutes
• Very early `inflation' invoked to explain uniformity of CMB

Lecture 43: Elements of life and how possibly initiated (Wed, 27 Apr)

• Building blocks for life forms
• How might life start, or have started
• Life's four ingredients on Earth
• Ecospheres around stars: zones of habitability
• Planetary surfaces may provide sites for spontaneous biochemistry

Lecture 44: Ecospheres and searches for extra-solar planets (Fri, 29 Apr)