Evolution of the UniverseEvolution of the UniverseFrom the Big Bang to the Big ChillFrom the Big Bang to the Big Chill

Dan Caton

What we will look atWhat we will look at

The Big BangThe Big BangStar formation Star formation

(with or without planets)(with or without planets)Stellar evolution and deathStellar evolution and deathThe Big ChillThe Big Chill------------- Questions and Break ------------------------ Questions and Break -----------The search for (intelligent?) life in the The search for (intelligent?) life in the UniverseUniverse

The Smoking Gun: Galaxies and their motionsThe Smoking Gun: Galaxies and their motions

Several Several hundred hundred billion starsbillion stars

Their Their motions motions revealed the revealed the expansion expansion of the of the UniverseUniverse

Billions of GalaxiesBillions of Galaxies

Hubble Ultra-Deep Hubble Ultra-Deep FieldField11.3 days of 11.3 days of exposure time exposure time 3 arc-minutes in 3 arc-minutes in sizesize10,000 galaxies10,000 galaxiesSeeing back to Seeing back to within 800 million within 800 million years of Big Bangyears of Big BangLet’s look at Let’s look at galactic motions….galactic motions….

Vesto M. SlipherVesto M. SlipherIn 1914 found 11 of 15 In 1914 found 11 of 15 spiral 'nebulae' spectra spiral 'nebulae' spectra showed spectral lines showed spectral lines Doppler shifted toward Doppler shifted toward the red......... the red.........

Milton HummasonMilton Hummason

In 1920's, worked In 1920's, worked his way up at Mt. his way up at Mt. Wilson to be night Wilson to be night assistant and assistant and observer.observer.

Photographed Photographed spectra of many spectra of many galaxies using... galaxies using...

… … the 100-inch Mt. Wilson telescopethe 100-inch Mt. Wilson telescope

These interpreted by...These interpreted by...

Edwin Hubble, who found that velocity proportional to distanceEdwin Hubble, who found that velocity proportional to distance

Plot means expansionPlot means expansion

Uniform Uniform expansion expansion means means velocities velocities are are proportionproportional to al to distancedistance

No No “center”—“center”—every every location location looks like looks like center!center!

Back up the Expansion: Big BangBack up the Expansion: Big Bang

Big Bang!

Remnants of BB were PredictedRemnants of BB were Predicted

In 1960 it was predicted that we should see the remnants of the Big Bang, Princeton physicists Robert Dicke and P. J. Peebles

Discovery!Discovery!

• Penzias and Wilson discover it in 1965

• Bell Labs / satellite communications

• detected isotropic static

• got 1978 Nobel prize in physics

Spectrum: 3Spectrum: 3oo Kelvin “Blackbody” Kelvin “Blackbody”

Origin of the 3Origin of the 3oo Cosmic Background Cosmic Background

Evidence of initial structureEvidence of initial structure

Wilkinson Microwave Anisotropy Probe (launched 6/01) – more details later…

The Stellar Era (now)The Stellar Era (now)

Current era of star formation will continueCurrent era of star formation will continue

100 trillion (10100 trillion (101414) years: stellar era ends) years: stellar era ends

Let’s make some stars…Let’s make some stars…

Star Formation: the NurseriesStar Formation: the Nurseries

Stars began Stars began to form in to form in areas of gas areas of gas and dust and dust very soonvery soon

Some Some fraction form fraction form with planetswith planets

Triggers Triggers needed needed for star formationfor star formation

Shock wave from Shock wave from passage of spiral passage of spiral arm in galaxy.arm in galaxy.Hot young blue Hot young blue stars define stars define formation regionsformation regions

Triggers for star formationTriggers for star formationSupernovae – Supernovae – either the death of either the death of massive stars or massive stars or explosion of explosion of accreted material accreted material in a binary star in a binary star system, create system, create shock waves in the shock waves in the regionregion

Outshines the rest of Outshines the rest of the galaxythe galaxy

Used as a “standard Used as a “standard candle” for finding candle” for finding galactic distancesgalactic distances

Triggers for star formationTriggers for star formation

Energetic Energetic ultraviolet ultraviolet light from light from new, hot new, hot stars stars generate generate shock shock waves waves that that trigger trigger other stars other stars to form.to form.

Proto-stars form in collapse…Proto-stars form in collapse…

Seen in Seen in visible and visible and infrared infrared images from images from HST here.HST here.Initially heat Initially heat from energy from energy of of gravitational gravitational collapsecollapseThen …Then …

Stars’ energy source: fusionStars’ energy source: fusion

Proton-proton cycleProton-proton cycleConverts hydrogen to Converts hydrogen to

helium:helium:Two protons combine to Two protons combine to deuterium + positron + deuterium + positron + neutrinoneutrinoAnother proton combines Another proton combines with this to make isotope with this to make isotope of helium + gamma rayof helium + gamma rayTwo of these He combine Two of these He combine to make He plus two to make He plus two protonsprotonsFinal mass less than Final mass less than ingredients by E = mcingredients by E = mc22

Products ….Products ….

Products: gamma rays and neutrinosProducts: gamma rays and neutrinos

Gamma rays take random Gamma rays take random walk out of star, absorbed walk out of star, absorbed and re-emitted at lower and re-emitted at lower temperatures and longer temperatures and longer wavelengthswavelengths

Neutrinos leave directly with Neutrinos leave directly with little interaction with matter. little interaction with matter. Used as a probe of solar Used as a probe of solar nuclear process…nuclear process…

Subsequent EvolutionSubsequent Evolution

These processes replenish the Universe with gas and dust…

Stellar Stellar EvolutionEvolution

The LightweightsThe Lightweights

Structure of evolving Low-Mass stars Structure of evolving Low-Mass stars

Core heats Core heats up and up and starts starts burning Heburning He

Outer Outer atmosphere atmosphere expands expands and coolsand cools

Firewood and the fireplace…

M57: theM57: the Ring Nebula Ring Nebula

Outer atmosphere is gently puffed off in a so-called “planetary” nebula

Remaining core becomes a “white dwarf,” like these…

… … White dwarfsWhite dwarfs

RealReal White dwarfs White dwarfs• Very dense—stellar mass within planet size

•Supported from collapse by electron degeneracy

• Mass must be less than the Chandrasekhar limit of 1.4 solar masses

Subrahmanyan Chandrasekhar.

HighHigh mass stars’ fate mass stars’ fate

Grows to become a red supergiant….

Fusing iron…Fusing iron…

Endothermic reactions

Stages of EvolutionStages of Evolution

Type II

What will happen to falling matter?What will happen to falling matter?

A) both balls (all A) both balls (all matter) will matter) will bounce to their bounce to their combined heightscombined heightsB) The big ball B) The big ball (core) will stop (core) will stop the small ballthe small ballC) The small ball C) The small ball (ejecta) will (ejecta) will bounce out morebounce out more

Core

Rebound is violent!Rebound is violent!Infalling matter Infalling matter rebounds rebounds dramatically due to dramatically due to conservation of conservation of momentummomentum

Outer material is Outer material is still falling in while still falling in while inner core is inner core is already already rebounding rebounding outwardoutward

Core

Prominent Historical Prominent Historical SupernovaeSupernovae

YearYear ObserverObserver StatusStatus

10541054 China, JapanChina, Japan Crab NebulaCrab Nebula

15721572 Tycho et al.Tycho et al. Tycho's Tycho's remnant remnant

16041604 Kepler et al.Kepler et al. Kepler’s Kepler’s remnantremnant

19871987 Southern Southern hemispherehemisphere monitoredmonitored

Supernova 1054Supernova 1054

Seen by Chinese in Seen by Chinese in 1054 AD1054 ADPossibly recorded Possibly recorded by native Americans by native Americans in Chaco Canyonin Chaco CanyonNot seen in Europe?Not seen in Europe?Visible in daylight for Visible in daylight for weeks weeks Today …Today …

Crab Nebula (M1) “supernova remnant”Crab Nebula (M1) “supernova remnant”

Tycho’s Star’s SNRTycho’s Star’s SNR

15721572

X-ray X-ray image image from from Chandra Chandra satellitesatellite

SN1987A in the Large Magellanic SN1987A in the Large Magellanic CloudCloud

Ian Shelton, Univ. Toronto, working in ChileIan Shelton, Univ. Toronto, working in Chile

LMC satellite of Milky Way Galaxy, 170kly LMC satellite of Milky Way Galaxy, 170kly awayaway

Important: first ‘nearby’ SN in modern timesImportant: first ‘nearby’ SN in modern times

The FutureThe Future

What can we tell from measurements of the expansion of the Universe?

Recent data..Recent data..

Look at details at upper end…

Models vs. data scatterModels vs. data scatter

Our new fate?Our new fate?

Let’s look at current model of the future… three more eras

The Degenerate EraThe Degenerate Era

Most of the mass is locked up in Most of the mass is locked up in degenerate stars, those that have blown degenerate stars, those that have blown up and collapsed into black holes and up and collapsed into black holes and neutron stars, or have withered into white neutron stars, or have withered into white dwarfs. dwarfs.

Energy in this era is generated through Energy in this era is generated through proton decay and particle annihilation. proton decay and particle annihilation.

Ends in 10Ends in 103737 years. years.

The Black Hole EraThe Black Hole Era

Protons have decayed (t >10Protons have decayed (t >103333 yr? yr? undetected yet) and black holes have undetected yet) and black holes have evaporated. evaporated.

After the epoch of proton decay, the only After the epoch of proton decay, the only stellar-like objects remaining are black stellar-like objects remaining are black holes of widely disparate masses, which holes of widely disparate masses, which are actively evaporating during this era. are actively evaporating during this era.

Ends at ~10Ends at ~10100100 years years

The Dark EraThe Dark Era

Only the waste products from these Only the waste products from these processes remain: mostly photons of processes remain: mostly photons of colossal wavelength, neutrinos, electrons, colossal wavelength, neutrinos, electrons, and positrons. and positrons.

For all intents and purposes, the universe For all intents and purposes, the universe as we know it has dissipated… the truly as we know it has dissipated… the truly Big ChillBig Chill

The (real) end.The (real) end.