Primary Text: Cosmic Perspective, 9th edition, Bennett et al. (2020).
All main reading assignments are from this book.
COPIES OF LECTURE SLIDES ARE POSTED AFTER EACH LECTURE (click on underlined links
that get you to Acrobat-readable pdf files -- slides here are six to a page for economy)
Reading prior to class: Chap 1 (Our place in the universe) and `How to succeed
in your astronomy course' (preface). Detailed course syllabus distributed (also
posted on website here). Homework Set #1 passed out (due Thur Jan 23). Register
your iClicker via myCUinfo site if not already registered. Set up your student
account on Modified Mastering Astronomy (MMA) site via our course Canvas
site (see instructions on pink Pearson passed-out sheet), linking to our course
named "ASTR1040TOOMRE2020". Carry out HW Assignment #0 on MMA site to become
familiar with its procedures. Recitations start this week, both on Tues and Wed.
Reading prior to class: Chap 3 (especially 3.4), Chap 4 (review
in detail), and then read carefully all of Chap 5 (Light and Matter). Demo of
emission tubes yielding spectral lines seen with plastic diffraction gratings.
- 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.....
- Nature of astronomy as a science
- Most fundamental assumptions: A. Copernican principle and B. Universality
of laws of nature
- Scientific method: what it is all about
- Four fundamental forces: gravity, electromagnetic, strong and weak
- Light as waves (and particles), involving the electromagnetic force
Reading prior to class: Read Chap 6 (Telescopes) thoroughly, survey read
Chap 14 (Our Star). Doppler effect demo.
- Great puzzle of planetary movements: Earth or Sun centric?
- The Copernicus - Tycho - Galileo - Kepler great eras of change and discovery
- Kepler and elliptic planetary orbits in clearly a Sun-centric system
- Newton and gravitation to explain Kepler's orbits
- How to live and feel the speed of "light"
- Why SI units have some merit, vs the "English" system
- Significance of "quantum mechanics": energy of a photon related to its frequency
- Interaction of light and atoms, yielding spectral lines unique to each atom
- Electron energy levels for hydrogen, and the birth of "quantum mechanics"
- Emission and absorption of light, and resulting spectra
Reading prior to class: Read Chap 6 (Telescopes) thoroughly, survey read
Chap 14 (Our Star). Homework Set #1 due in class. Homework Set #2 passed out.
- Kirchoff's Laws about emission and absorption features
- Continuous spectrum emitted by hot solid or high-density gas
- Thin hot cloud can absorb photons of light passing through it, yielding a
"dark-line" spectrum (absorption) unique to the elements in that cloud
- Thin hot cloud glowing by itself yields a "bright line" spectrum (emission),
again unique to the elements in cloud
- Subtleties of the 'black body' or thermal radiation spectrum
- Doppler effect for both sound and light: shift the frequency/wavelength
Reading prior to class: Complete reading Chap 14 (Our Star). Demo on pointing
space telescopes. Homework #1 returned graded, plus answer sheet. Observatory Night #1,
this Thur Jan 30, starting 7:00pm, by sign-up.
- Doppler broadening by rotation of star
- Supermassive black hole discovered in center of M84 using Doppler shifts
- And just what is the wavelength/frequency of your cell phone?
- Principles common to our eyes, cameras, telescopes
- Examine range of big telescopes used in astronomy
- Effects of our atmosphere on light
- Light pollution, twinkling by turbulence, absorption by atmosphere
- Reflectors prevail over refractors for astronomy (discussion)
- Resolution and sensitivy of telescope improved by size of mirror (or lens)
Class meets in Fiske Planetarium to study our position in our galaxy with spiral
arms, richness of star-forming regions like Orion in multiple wavelengths, and the
full-dome Lucas program on "Solar Superstorms". Go directly to Fiske.
Reading prior to class: Second reading of Chap 14 (Our Star).
Start reading S4 `Building blocks of universe', to be discussed in next week's
recitations (especially S4.1 and S4.2). Homework Set #2 due in class at Fiske.
Homework Set #3 passed out. Observatory Night #1 tonight.
- Adaptive optics is able to remove many image distortions by atmospheric turbulence
- What light gets through our atmosphere, what does not
- Nature of instruments on telescopes for real analysis
- How and what do we observe from space
- Conserving angular momentum, useful to point space telescopes
- X-ray telescopes (grazing reflections)
- Radio telescopes (often arrays of dishes, and `aperture synthesis')
- Discussion of instrumentation in focal plane of different telescopes:
imaging, spectroscopy, timing
NASA Solar Dynamics Observatory (SDO) web site reveals images/movie sequence of
Sun in glorious UV detail, with rich structuring in atmosphere from magnetism.
Consider the discussion question on 'How do we test/deduce what is deep within the Sun'.
Observatory Night #2 on this Thur Feb 6, starting at 7:00pm by signup.
- Planetarium visit begins with brief lecture
- Overview of our nearest star, the Sun
- Regions of the Sun and their function: core, radiative zone,
convective envelope, atmosphere
- Why is a star round? Equilibrium between pull of gravity and push of pressure
- Why does the Sun shine? Fusion reactions convert H to He, keep the center very hot
- Front page in NY Times: DKIST solar telescope first images and videos
Reading prior to class: Re-read 14.3 on solar magnetism with care.
Homework Set #3 due in class. Homework #4 passed out. Also Review Set #1, in
preparation for First Mid-Term Exam in class next Thur Feb 13. Demo on the
"strength of pressure" to collapse steel drums (and hold up the Sun!). Observatory
Night #2 tonight.
- Overview of solar structure from inside out
- Solar granulation and surface convection: also source of solar sound waves
- Fusion reactions (p-p chain) convert H to He, center very hot
- Examine details of p-p fusion, including making neutrinos and gamma-ray photons
- Energy yield from H fusion is vastly greater than from chemical burning!
- Fusion burning of 1 kg of H into He (7 grams turned into energy) is equivalent
to chemical burning of two units trains of coal (200,000 Tons)!
Reading prior to class: Overview read Chap 15 on properties of stars.
Evening review session by Max Weiner this Wed evening, Duane G-130 (6pm-8pm),
to help prepare for First Mid-Term Exam in class on Thur Feb 13. Demo on making
electromagnetic waves and lightning with a Tesla Coil.
- Puzzle of the solar neutrinos: how to capture these elusive particles, and thus
test products of p-p chain
- Workings of the solar thermostat to maintain stable energy production in core
- How temperature and density varies with radius inside the Sun
- Examining solar granulation and sunspot structures in high-resolution detail
- How sampling of sound waves at the solar surface yields probes of the interior
- What helioseismology tells us about interior flows and structures
- Measuring magnetic field strengths in sunspots with Zeeman splitting of
- Coronal mass ejections and flares from magnetic field reconnections
Reading prior to class: Complete overview read Chap 15 on properties of stars.
Homework Set #4 due in class, new Homework #5 passed out. The First Mid-Term Exam
occupies the last 50+5 minutes in class.
- The solar magnetic cycle involving sunspots and variable activity
- Extensive EUV video sequences of coronal loops and flaring, and coronal mass
ejections, as captured with both SOHO and SDO satellites
- Solar magnetic fields and their complex 11-year cycles
- Use of supercomputers to simulate dynamics (convection and magnetic dynamos)
deep within the Sun
- Solar magnetism, solar wind, space weather and northern lights
- Effects of solar activity on our planet... and our technological society
Reading prior to class: Read Chap 15.1: `Properties of stars' in detail, and 15.2
in overview. Mid-Term Exam 1 returned graded, and so too Homework #4 graded.
Observatory #3 signup for this Wed Feb 19.
- Observing stars other than the Sun: brightness, position, spectrum
- Devising a classification for stars based on absorption features in spectra
(O,B,A,F,G,K,M) [Annie Cannon]
- Why surface temperature of star and spectral classification (O,B,A ..)
are closely linked [Cecelia Payne-Gaposchkin]
- Turn to First Mid-Term Exam for the rest of class period
Focus on reading 15.2 `Patterns among stars' carefully, and then turn to 15.3
'Star clusters'. Survey read Chap 16 (Star Birth). Homework Set #5 due today,
new HW #6 passed out. Observatory #4 signup for coming Tues Feb 25.
- Stellar luminosity and apparent brightness
- Distance from stellar parallax
- Revisit devising a classification for stars based on absorption features in spectra
(O,B,A,F,G,K,M) [Annie Cannon]
- Cecelia Payne-Gaposhkin showed that Saha equation can explain spectral
classification (O,B,A,F,G,K,M) in terms of surface temperature of star
- Saha equation predicts ionization states of different elements, with
resulting spectral line strengths most sensitive to temperature
- Luminosity classes by width of spectral lines (I, II to V)
- Where different stars lie on H-R diagram in overview
- Measuring brightness of stars: apparent vs absolute magnitude (luminosity)
requires knowing distance
- Determine radii of stars, if know luminosity and temperature
Read Chap 16.1 'Stellar nurseries' and 16.2 'Stages of star birth' with some care.
Observatory #4 tonight, can still signup. `Stellar Evolution Overview' sheet passed out.
- Brief overview of where different stars lie on H-R diagram
- Determine radii of stars, if know luminosity and temperature
- Four varieties of binary stars (based on detection)
- Estimating stellar masses from binary star data -- the only way to determine
masses of stars other than by theory
- `Observed' mass-luminosity relation for main sequence stars
- 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!
- Estimate how lifetimes on main sequence vary with stellar mass
- Outcome: massive stars have very short lifetimes on main sequence
Reading prior to class: Overview read Chap 17 `Star Stuff', and in detail
17.2 `Life as Low-Mass Star'. Read 18.1 `White Dwarfs' with care (end of evolution
for low-mass stars). Homework #6 due in class, new HW #7 available. Observatory #5
signup for coming Tues Mar 3.
- Complete discussion of lifetime of stars on main sequence
- Cities of stars come in two varieties: open clusters (small) and globular
- Test ideas about evolution by looking at H-R diagrams of star clusters
- Peel-off from main sequence helps estimate age of cluster
- Overview of spiral galaxy: stars and gas in disk rotate faster than spiral
pattern, with gas compressed as they enter these `traffic jams', leading to
vigorous star birth in molecular clouds
- How large clouds of gas and dust (recycled from previous generations in spiral
galaxy) may begin to collapse and form new stars
- Tyranny of too much angular momentum as star is being assembled
- Seeing into the `dusty cocoons' with near infrared wavelengths
- Nuclear furnaces slowly turn on and protostar approaches the main sequence
Read 17.2 `Life as High-Mass Star' with some care, and both 18.2 `Neutron stars'
and 18.3 `Black Holes' in overview. Observatory Night #5 tonight, signup.
- Revisit stages in star birth, on the way to joining the main sequence
- 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 in red giant's core
- Helium flash in core (triple-alpha burning of He) removes degeneracy
- Burning He in core (horizontal branch)
- Discussion on `City of Stars' as sampling stellar evolution in a population
- Red supergiant phase (with double-shell burning of H and He)
- Planetary nebula involves shells `puffed off' from supergiant
- Remarkable shapes of planetary nebulae (PN): what may cause these?
- Why electron degeneracy pressure can only support a white dwarf up to
1.4 solar masses
- White dwarf of one solar mass is roughly Earth-size; more massive are smaller!
Go directly to Fiske, trying to arrive on time. Program on flying through our
Milky Way galaxy to experience spiral structure, star birth regions as jewels
in the sky, multi-views of Orion Nebula, and galaxies in many flavors. Full
digital-sky projection of the superb "Black Holes: The Other Side of Infinity"
program produced by Gates Planetarium at the Denver Museum of Science and Nature (DMSN).
Reading prior to class: Read 18.2 `Neutron stars' in detail.
Review Set #2 passed out for Second Mid-Term Exam on Thur Mar 12
in class. Observatory Night #6 on Tues March 10. Homework Set #7 due
in class, new HW #8 passed out.
- Revisit white dwarfs briefly
- Overview of massive star evolution
- 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!
- Strong winds from massive stars, even big ejecta (Eta Carinae)
- Sudden brightening of massive red giants/supergiants can yield "light echos"
- With enough core mass of iron, electron degeneracy can no longer support
the star: `core collapse' supernova explosion
- Supernovae (SN) can create neutron stars, formed from their collapsed
- SN explosion leads to nucleosynthesis, making most elements in universe
heavier than iron
- Remnant left behind could be a neutron star, supported by neutron degeneracy
pressure, or black hole
- Pulsars: rapidly rotating neutron stars with fierce magnetic fields
- Listen to radio emission from several pulsars (some go with heavy metal
beat, others like bongo drums, some are a fast buzz!)
Reading prior to class: Review 18.1 `White Dwarfs' for role of mass transfer
in binary systems. Evening review session by Max Weiner this Wed evening,
Duane G130 (6pm-8pm), to help prepare for Second Mid-Term Exam in class on Thur
Mar 12. Observatory Night #6 tonight, signup.
- Brief revisit of massive star evolution, ending in core-collapse supernova
- Discovery of radio pulses from unknown source, with very steady beat!
- Detailed look at pulsars: rapidly rotating neutron stars with fierce
- Synchrotron radiation is source of intense light beamed by pulsars
- Pulsars: `lighthouses in the sky' gradually slow down, using rotational energy
to power the beams
- Fly through our galaxy, with stopping at many places, using full Fiske Sky
- "Black Holes: The Other Side of Infinity" (23 minute DMSN and Nova program,
with CU faculty involved in original production)
Reading prior to class: Start overview reading of Chap 19 `Our Galaxy'. Homework
Set #8 due in class, new HW #9 passed out. Second Mid-Term Exam occupies last
50 minutes of class.
- Revisit synchrotron radiation providing the beams from pulsars
- Demo of one variant of neutron star (the `bowling ball').
- Crab nebula supernova (4 July 1054) and pulsar show stunning behavior
in Chandra and Hubble movies
- Mass exchange by Roche lobe overflow in binary system: Algol paradox
- How mass transfer onto a neutron star in a binary system can spin it up
- 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'
- Observational differences between massive-star `core-collapse supernovae'
(Type II) and white-dwarf supernovae (Type I)
- With white-dwarf SN, nothing left behind, as seen with Brahe and Kepler
- Hot accretion disks always formed around objects on receiving end of
binary mass transfer
- Similar mass transfer onto neutron stars, with helium flash burning,
may explain x-ray bursters
Reading prior to class: Read 18.3 carefully. Begin overview read of Chap 19,
"Our Galaxy" (Milky Way), and of S2 "Space and Time" (Special Relativity).
Second Mid-Term Exam would be returned graded, and so also Homework #8; but we cannot
do so physically, since we are now only teaching and learning remotely and the APS
office is closed this week. Grades for Second MT Exam 2 have been posted on
Canvas, and so too answers and grade boundaries. Homework #8 grades and answers, and so
for future homeworks, will be posted on Canvas. All actual papers will be available
after the Covid-19 emergency abates. Instructions to join Zoom sessions for these
lectures and recitations will be emailed one-day in advance of specific classes
and recitations at the standard class times.
- Revisit white-dwarf supernovae, and how they become "standard candles"
- Supernova 1987A as an explosion of a star in the nearby Large Magellanic Cloud
observed ~160,000 years later by us on 24 Feb 1987 with modern equipment and
- Star was a bright blue supergiant, so core-collapse supernova, with
likely neutron star or black hole (but currently obscured)
- Brief burst of neutrinos detected from this SN for the first time
- Evolving structure, shocks and emission from SN 1987A -- seeing changes
in `real time', as also predicted by Dick McCray here at CU
- As blast wave arrives at previous ejecta, systematic heating and brightening
of seemingly ring-shaped structure
- Examined other famous SN remnants in Milky Way, from the time of Flamsteed
in ~1680 (Cassiopeia A, with neutron star at center), Kepler in 1604
(probably white-dwarf SN), and Tycho Brahe in 1572
Reading prior to class: Read Chap 19.1 and 19.2 with some care. New Homework Set
#10 posted on Canvas; HW #9 due by class time, via submission of Part 9B on Canvas.
Overview read Chap 20, including over Spring Break if time and setting allows.
Class interactive lecture is presented remotely via Zoom at class time, with
details to join emailed on prior day Wed Mar 18.
- 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
- Ergosphere: a spinning black hole drags nearby spacetime along
- Overview of 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'
Reading prior to class: After reviewing 19.2 and "star-gas-star" cycling, focus
on 19.3 and 19.4. Finish overview reading of Chap 20 "Galaxies and Foundations
Modern Cosmology", and S3 "Spacetime and Gravity". Class meets via Zoom. All
observatory sessions cancelled, including Observ #7 scheduled for Wed Apr 1.
- What happens from view of mothership or probe when approaching a black hole
- Return to black holes topic: How to detect a black hole
- Cygnus X-1 first 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
- Motion of stars in our galaxy: disk stars in nearly circular motion, halo
and bulge stars in swooping orbits that dive through disk
- Elements involved in building a spiral galaxy like our own Milky Way
- Explaining rotation curve with radius in disk calls for much more matter than
is visible: thus `dark matter'
- Our galaxy, like most, embedded in a much large spherical halo of dark matter
- Inventory of galaxy disk: stars (~90% by mass), gas (~10%), dust (1%)
- A little dust goes a long way in absorbing/obscuring light
- Interstellar medium (ISM), or stuff between the stars: its various
Reading prior to class: Read with some care 20.2 `Measuring Cosmic
Distances' and 20.3 `Age of Universe'. New Homework Set #11 posted on Canvas;
HW #10 due by class time, via submission of Part 10B on Canvas. Class meets via Zoom.
- Revisit "inventory" of interstellar medium (ISM) states: cold, warm, hot,
- Superbubbles blown by multiple supernovae, can even burst out of galactic disk
- Remarkably different views of ISM at distinct wavelength ranges
- First look at spiral patterns outlined by bright O & B star associations
- Resulting beautiful structures in star birth regions with O and B stars
carving out holes
- Examine how spiral patterns are made in the disks of galaxies,
including our own: gas and stellar traffic jams
- Spiral patterns outlined by bright O & B star associations, with
vigorous star birth occurring in spiral arms through compression of
- What a micron-sized dust particle looks like, and how it absorbs and reddens
- Longer wavelenghts of infrared and radio waves can see through the dust
Reading prior to class: Start overview reading of Chap 21 `Galaxy Evolution'.
Re-read 20.1 `Islands of Stars' carefully, and review 20.2 `Measuring Galactic
Distances' and 20.3 `Age of Universe', with the latter in effect 'Hubble's Law'
on expansion of universe.
- Role of dust in absorbing/scattering light, with mischief in confusing
- Radio observation in 21-cm line of atomic hydrogen (HI) provide mapping of
spiral structure in disk of our Milky Way
- Radio astronomy of 21-cm emission from spin up/spin down transition in HI
paved the way for MRI imaging in medicine
- How we map spiral structure in our galaxy, with Doppler shift of 21-cm line
- Detailed observational evidence for supermassive black hole (SagA*) at center
of Milky Way
- A great step forward in 1924 with new 100-inch Hooker telescope on Mt Wilson
above Pasadena and LA
- Edwin Hubble is able to distinguish Cepheid variables in Andromeda, shows that
it lies way outside of Milky Way -- thus there are other island universes, now
- Classifying galaxies by appearance and shape: spirals, barred spirals,
ellipticals, irregulars (Hubble's `tuning fork')
- Great surprises from Spitzer space telescope imaging Andromeda in infra-red
Reading prior to class: Detailed read of 21.1 `Looking Back Through Time' and
21.2 `Lives of Galaxies'. Examine 21.3 'Role of Supermassive Black Holes'.
New Homework Set #12 posted in Canvas, HW #11 due by 6pm via download
- What sample galaxies (spirals, barred spirals, ellipticals) look like, and
- 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
- Hubble busily measures redshifts of many galaxies, announcing in
1929 that redshifts of galaxies appear to increase with distance from us
- Hubble's Law and what it means: we are in an expanding universe!
- Measuring cosmic distances is a big challenge: identify `standard candles'
- Parallax, main-sequence fitting, Cepheid variables, Tully-Fisher relation
and white dwarf each provide ways to estimate increasingly greater distances
- Distance ladder using overlapping standard candles
Reading prior to class: Careful study of 21.3 'Role of Supermassive Black Holes'
and 21.4 `Gas Beyond the Stars'. Review Set #3 posted in Canvas/Modules,
for Third Mid-Term Exam scheduled for Tues Apr 21 on Canvas/Quizzes during
- 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
- Quasars - how discovered at large redshifts through bright emission lines
- Model of `active galaxies', including quasars: 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
- Examine radio galaxies for their synchrotron emission from jets and tails
- Visit elliptical galaxy Centaurus A with jet and central supermassive black
hole (SBH); has big dust lane and is radio source with big lobes
- Remarkable scaling of SBH in many galaxies with their halo masses
- 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
Reading prior to class: Begin overview reading of Chap 22 'Birth of Universe'.
Read 23.2 `Evidence for Dark Matter' in detail for this lecture, even if it jumps
ahead in our book.
New Homework Set #13 posted in Canvas, HW #12 due by 6pm via download
- Modelling the possible future crash of Andromeda with our Milky Way
- Many messages from galaxy interactions (collisions):
- 1. Must be common early in dense clusters
- 2. Spiral galaxies can tumble together to form elliptical galaxy
- 3. Vastly increased star birth (starburst)
- 4. Rapid feeding of massive black hole (quasars and radio galaxies);
- 5. Rapid variability of quasars says that emission region is very small
- Revisit "active galactic nuclei" (AGN), for the beautiful emission tails
or jets revealed by radio telescopes.
- Examine very high resolution images by HST of accretion disks around the
central supermassive black holes in elliptical galaxies hosting an AGN
Review Session for exam given by Max Weiner on Mon, Apr 20, 4pm-6pm via Zoom, with Review Set #3
posted on Canvas/Modules. Third Mid-Term Exam available Tues Apr 21 (11:00am-12:15pm, 75 min)
for full class interval by going directly to Canvas/Quizzes. Complete overview reading of Chap 22
'Birth of Universe' prior to the next class.
Reading prior to class: Complete detailed read Chap 22 'Birth of Universe'.
Focus on 22.2 `Evidence for Big Bang', and Cosmic Microwave Background (CMB) there.
Third Mid-Term Exam returned graded, with grade boundaries. HW #13 due by 6pm via
download (some flexibility). Consider completing Observatory Night Project report,
- Case for dark matter as huge surrounding halo to spiral galaxy: Flat
- Galaxy clusters reveal presence of dark matter in three ways:
- 1. Large random velocities of member galaxies,
- 2. Hot x-ray emitting gas in cluster,
- 3. Gravitational lensing by galaxy clusters
- Many examples now of gravitational lensing by clusters
- Just what might be dark matter? MACHOs and WIMPS may offer possibilities
- Cosmological models of universe, first look
Reading prior to class: Re-read in detail both 23.4 'Dark Energy and Fate of
Universe' and 22.1 `Big Bang Theory'. Overall Review Sheet #4 posted. Final review session
for the course is on Mon, May 4, 4:30pm-6:30pm by Max Weiner on Zoom.
- Cosmological models of universe
- Brief history of how Einstein's General Relativity Theory (GRT) was
quickly used by Friedman and Lemaitre
- Dark matter and fates of universe
- Three choices for fate of universe: coasting (open), critical (flat),
- Cosmic microwave background (CMB) and its many implications
- Subtle aspects of the very small variations in CMB
Reading prior to class: Review both 23.4 'Dark Energy and Fate of
Universe' and 22.1 `Big Bang Theory'. Final Exam for course is on
Wed May 6, 4:30pm-7:00pm, on Canvas/Quizzes, in accord with Registrar.
- Implications of high-resolution mapping of CMB
- Dark energy approximately ~68%, cold dark matter ~27%, ordinary (baryonic)
- Remarkable that stars make up only about 10% of ordinary matter: the vast
majority must be intergalactic gas, especially amidst the giant clusters
of galaxies, as seen in strong x-ray emission
- This is an accelerating flat universe with dark energy as key ingredient
- Gamow led the way with calculating nucleosynthesis within the
big bang and which elements would be produced - looking at first 3 minutes
in the `fires of creation'
- Discuss rapid eras of particles, nucleosynthesis, and nuclei
- Recombination: after 380,000 years, universe cooled to about 3000K,
atoms can form and photons can begin to travel freely -- now viewed as CMB
- Era of galaxies and stars started after about 1 billion years
- Simulations reveal large-scale structure formation in universe, leading
to voids and sheets and galaxy clusters
- These major cosmological simulations (Millenium, Illustris, ...) reveal
crucial role of cold dark matter in resulting structure
- Ordinary barionic matter and photons by being too
mobile (or hot) would not build such large-scale structures themselves, but
barionic matter would be pulled into the gravitational wells in due course
- Discuss the great outstanding questions about cosmology and our universe
- Revisit our Andromeda galaxy (M31) for a celebration of what high-resolution
IR imagery from space can reveal
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