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Evolution of the Universe From the Big Bang to the Big Chill Dan Caton.

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Presentation on theme: "Evolution of the Universe From the Big Bang to the Big Chill Dan Caton."— Presentation transcript:

1 Evolution of the Universe From the Big Bang to the Big Chill Dan Caton

2 What we will look at The Big Bang Star formation (with or without planets) (with or without planets) Stellar evolution and death The Big Chill Questions and Break The search for (intelligent?) life in the Universe

3 The Smoking Gun: Galaxies and their motions Several hundred billion stars Their motions revealed the expansion of the Universe

4 Billions of Galaxies Hubble Ultra-Deep Field 11.3 days of exposure time 3 arc-minutes in size 10,000 galaxies Seeing back to within 800 million years of Big Bang Let’s look at galactic motions….

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

6 Milton Hummason In 1920's, worked his way up at Mt. Wilson to be night assistant and observer. Photographed spectra of many galaxies using...

7 … the 100-inch Mt. Wilson telescope These interpreted by...

8 Edwin Hubble, who found that velocity proportional to distance

9 Plot means expansion Uniform expansion means velocities are proportion al to distance No “center”— every location looks like center!

10 Back up the Expansion: Big Bang Big Bang!

11 Remnants 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

12 Discovery! Penzias and Wilson discover it in 1965 Bell Labs / satellite communications detected isotropic static got 1978 Nobel prize in physics

13 Spectrum: 3 o Kelvin “Blackbody”

14 Origin of the 3 o Cosmic Background

15 Evidence of initial structure Wilkinson Microwave Anisotropy Probe (launched 6/01) – more details later…

16 The Stellar Era (now) Current era of star formation will continue 100 trillion (10 14 ) years: stellar era ends Let’s make some stars…

17 Star Formation: the Nurseries Stars began to form in areas of gas and dust very soon Some fraction form with planets

18 Triggers needed for star formation Shock wave from passage of spiral arm in galaxy. Hot young blue stars define formation regions

19 Triggers for star formation Supernovae – either the death of massive stars or explosion of accreted material in a binary star system, create shock waves in the region Outshines the rest of the galaxy Used as a “standard candle” for finding galactic distances

20 Triggers for star formation Energetic ultraviolet light from new, hot stars generate shock waves that trigger other stars to form.

21 Proto-stars form in collapse… Seen in visible and infrared images from HST here. Initially heat from energy of gravitational collapse Then …

22 Stars’ energy source: fusion

23 Proton-proton cycle Converts hydrogen to helium: Two protons combine to deuterium + positron + neutrino Another proton combines with this to make isotope of helium + gamma ray Two of these He combine to make He plus two protons Final mass less than ingredients by E = mc 2 Products ….

24 Products: gamma rays and neutrinos Gamma rays take random walk out of star, absorbed and re-emitted at lower temperatures and longer wavelengths Neutrinos leave directly with little interaction with matter. Used as a probe of solar nuclear process…

25 Subsequent Evolution These processes replenish the Universe with gas and dust…

26 Stellar Evolution The Lightweights

27 Structure of evolving Low-Mass stars Core heats up and starts burning He Outer atmosphere expands and cools Firewood and the fireplace…

28 M57: the Ring Nebula Outer atmosphere is gently puffed off in a so-called “planetary” nebula Remaining core becomes a “white dwarf,” like these…

29 … White dwarfs

30 Real 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.

31 High mass stars’ fate Grows to become a red supergiant….

32 Fusing iron… Endothermic reactions

33 Stages of Evolution Type II

34 What will happen to falling matter? A) both balls (all matter) will bounce to their combined heights B) The big ball (core) will stop the small ball C) The small ball (ejecta) will bounce out more Core

35 Rebound is violent! Infalling matter rebounds dramatically due to conservation of momentum Outer material is still falling in while inner core is already rebounding outward Core

36 Prominent Historical Supernovae YearObserverStatus 1054 China, Japan Crab Nebula 1572 Tycho et al. Tycho's remnant 1604 Kepler et al. Kepler’s remnant 1987 Southern hemisphere monitored

37 Supernova 1054 Seen by Chinese in 1054 AD Possibly recorded by native Americans in Chaco Canyon Not seen in Europe? Visible in daylight for weeks Today …

38 Crab Nebula (M1) “supernova remnant”

39 Tycho’s Star’s SNR 1572 X-ray image from Chandra satellite

40 SN1987A in the Large Magellanic Cloud Ian Shelton, Univ. Toronto, working in Chile LMC satellite of Milky Way Galaxy, 170kly away Important: first ‘nearby’ SN in modern times

41 The Future What can we tell from measurements of the expansion of the Universe?

42 Recent data.. Look at details at upper end…

43 Models vs. data scatter

44 Our new fate? Let’s look at current model of the future… three more eras

45 The Degenerate Era Most of the mass is locked up in degenerate stars, those that have blown up and collapsed into black holes and neutron stars, or have withered into white dwarfs. Energy in this era is generated through proton decay and particle annihilation. Ends in years.

46 The Black Hole Era Protons have decayed (t >10 33 yr? undetected yet) and black holes have evaporated. After the epoch of proton decay, the only stellar-like objects remaining are black holes of widely disparate masses, which are actively evaporating during this era. Ends at ~ years

47 The Dark Era Only the waste products from these processes remain: mostly photons of colossal wavelength, neutrinos, electrons, and positrons. For all intents and purposes, the universe as we know it has dissipated… the truly Big Chill

48 The (real) end.


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