Universe: Past, Present & Future
Northeastern Illinois University
Universe: Past, Present & Future Review
Greg Anderson Department of Physics & Astronomy Northeastern Illinois University
Spring 2018
c 2012-2018G. Anderson Universe: Past, Present & Future – slide 1 / 92 Northeastern Illinois Overview University
The Basics Solar System The Sun Stars Galaxies & Cosmology
c 2012-2018G. Anderson Universe: Past, Present & Future – slide 2 / 92
Northeastern Illinois Our motion in the Universe University
c 2012-2018G. Anderson Universe: Past, Present & Future – slide 4 / 92 Northeastern Illinois University
Cosmic Address Our motion in the Universe
The Basics Light-Year Light Distance Scales Time-Scales Cosmic Calendar Year Constellations The Basics Angles Solstice, Equinox & Seasons Peri & Apogee Fig: Phases Umbra, Penumbra & Antumbra Lunar Eclipses Solar Eclipses Greek Geocentric Cosmology Copernicus Kepler’s Laws Planet Speeds Galileo Galileo II Newton’s Laws Q: c Free2012-2018G. fall Anderson Universe: Past, Present & Future – slide 5 / 92 Newton’s Law of Northeastern Illinois Light-Year University
A light-year is the distance light travels in a year. The speed of light is:
c 3 108 meters/second = 300, 000km/s ≈ × In one year, light travels a distance:
1ly = 3 105 km (1year) 365 days 24 hours 3600 seconds × second 1year 1day 1hour = 9, 460, 000, 000, 000km
= 9.46 1012 km × The farther away we look in the distance, the farther back we look in time.
c 2012-2018G. Anderson Universe: Past, Present & Future – slide 6 / 92 Northeastern Illinois Measuring Distances with Light University
Earth-Moon distance 1.3 light-seconds Earth-Sun distance 8.3 light-minutes Pluto semi-major axis 5.5 light-hours Oort Cloud-Sun distance 41-82 light-weeks Alpha Centauri System 4.2 light-years Milky Way diameter 100,000 years Andromeda distance 2.5M years
c 2012-2018G. Anderson Universe: Past, Present & Future – slide 7 / 92 Northeastern Illinois Astronomical Distances University Earth’s Orbit (1 Astronomical Unit)
1AU=1.496 108 km × Distance Light Travels in 1 year
1light-year = 9.46 1012 km × Parsec 1parsec (pc) = 3.09 1013 km 3.26 light-years × ≈ Galactic Diameter: 30 100 kpc − 1kiloparsec (kpc) = 1000pc 3.26 103 light-years ≈ × Distance between Galaxies
1megaparsec (Mpc) = 106 pc 3.26 106 light-years ≈ × c 2012-2018G. Anderson Universe: Past, Present & Future – slide 8 / 92 Northeastern Illinois Cosmological Time-Scales University
The Earth
t =4.54 0.05 billion years ± Our Sun t =4.57 billion years Oldest Stars t = 12.5 1.5 billion years ± The Universe t = 13.6 1.5 billion years c 2012-2018G. Anderson ± Universe: Past, Present & Future – slide 9 / 92 Northeastern Illinois Cosmic Calendar Year University Jan 1: The Big Bang • February: Milky Way forms • Sept 3: Earth forms • Sep 22: Early life on earth • Dec 17: Cambrian Explosion • Dec 26: Rise of Dinosaurs • Dec 31 (9pm): Early hominids • Dec 31 (11:58pm): Modern humans • Dec 31 (11:59:49pm): Pyramids • Dec 31 (11:59:59pm): We learn Earth is a planet orbiting the Sun. •
c 2012-2018G. Anderson Universe: Past, Present & Future – slide 10 / 92 Northeastern Illinois Constellations University
On a clear night, in a dark place (not Chicago) you • can see a few thousand stars in the night sky. People from nearly every culture gave names to • patterns of stars in the sky. Our familiar constellations originated in Mesopotamia • over 5000 years ago. In 1928, the International Astronomical Union (IAU) • established 88 official constellations with well defined boundaries.
c 2012-2018G. Anderson Universe: Past, Present & Future – slide 11 / 92 Northeastern Illinois Degrees, Arcminutes, Arcseconds University
Degrees and Radians
360◦ =2π radians 2π 1 1◦ = radians radians 360 ≈ 60 Sixty arcminutes per degree:
1◦ = 60′
C =2πr Sixty arcseconds per arcminute:
1′ = 60′′
c 2012-2018G. Anderson Universe: Past, Present & Future – slide 12 / 92 Northeastern Illinois Solstice, Equinox & Seasons University
summer atumn atumnal equinox
winter summer solstice solstice
vernal equinox winter spring
Solstice: Either of two times a the year when the sun is at its • greatest distance from the celestial equator. Equinox: Two times a year when: the sun crosses the celestial • equator, length of day = length of night, tilt of the Earth’s axis is inclined neither away from nor towards the Sun.
c 2012-2018G. Anderson Universe: Past, Present & Future – slide 13 / 92 Northeastern Illinois Moon at Perigee & Apogee University
c 2012-2018G. Anderson Universe: Past, Present & Future – slide 14 / 92 Northeastern Illinois Fig: Moon Phases University
c 2012-2018G. Anderson Universe: Past, Present & Future – slide 15 / 92 Northeastern Illinois Umbra, Penumbra & Antumbra University antumbra
umbra penumbra
Looking towards the Sun from the... Umbra Penumbra Antumbra
Total Eclipse Partial Eclipse Annular Eclipse
c 2012-2018G. Anderson Universe: Past, Present & Future – slide 16 / 92 Northeastern Illinois Lunar Eclipses University
c 2012-2018G. Anderson Universe: Past, Present & Future – slide 17 / 92 Northeastern Illinois Solar Eclipses University
c 2012-2018G. Anderson Universe: Past, Present & Future – slide 18 / 92 Northeastern Illinois Greek Geocentric Cosmology University
⋆ Stars Saturn Y X Jupiter Mars ♂ ☼ Sun Venus ♀ ' Mercury Moon $ ♁ Earth
Aristotle’s crystalline spheres
c 2012-2018G. Anderson Universe: Past, Present & Future – slide 19 / 92 Northeastern Illinois Nicolaus Copernicus (1473 - 1543) University Polish astronomer, Nicolaus Copernicus (1473 - 1543) published De Revolutionnibus Orbium Coelestium: a detailed Heliocentric Model of the universe just before his death in 1543 (See also: Aristarchus, 310-230 BC).
♂ ♁
Heliocentric Model
73 years would pass before De Revolutionibus was listed as a forbidden work by the Church.
c 2012-2018G. Anderson Universe: Past, Present & Future – slide 20 / 92 Northeastern Illinois Kepler’s Laws University
Based on the meticulous observations of Tycho de Brahe (1546-1601), Kepler formulated the three laws which bear his name:
Law of Ellipses (1609) • The orbit of every planet is an ellipse which the Sun located at one focus. Law of Equal Areas (1609) •
a A line connecting the Sun and a planet 2 sweeps out equal areas in equal times. Harmonic Law (1618) • p2 = a3
c 2012-2018G. Anderson Universe: Past, Present & Future – slide 21 / 92 Northeastern Illinois Orbital Speeds of Planets University
12 vp =2πr v =2π r =2π r ⇒ p r3/2 10 bc Mercury
8 bc Venus bc 2π GM 6 v = = ⊙ bc √r q r Mars (AU/years)
v 4 Jupiterbc Saturn bc Uranus 2 bc Neptunebc
0 0 10r (AU) 20 30
c 2012-2018G. Anderson Universe: Past, Present & Future – slide 22 / 92 Northeastern Illinois Galileo Galilei (1564-1642) University
Made substantial contributions to the scientific method by the use of mathematics and experiment. Argued for the Heliocentric Copernican model.
Devised experiments and observations which refuted Aristotle and • Plato: Moving objects remain in motion unless acted on by a force. 1610 built a telescope, and discovered: • 1. four moons of Jupiter 2. phases of Venus 3. Sun spots 4. Craters and mountains on the Moon Argued stars are too disant for observable parallax • c 2012-2018G. Anderson Universe: Past, Present & Future – slide 23 / 92 Northeastern Illinois Galileo Galilei (II) University
1623: Dialogue Concerning the Two Chief World Systems compared the Copernican and Ptolemaic systems.
Ordered to stand trial by the Catholic church in 1633, found “vehemently suspect of heresy”, forced to recant by the Inquisition, and was placed in house arrest for the rest of his life.
c 2012-2018G. Anderson Universe: Past, Present & Future – slide 24 / 92 Northeastern Illinois Newton’s Laws of Motion University
From Newton’s Principia 1687: I. An object moves at a constant velocity if no net force is acting. II. Force equals mass times acceleration.
F = ma
III. For every force, there is an equal and opposite reaction force.
Fa b = Fb a on − on
c 2012-2018G. Anderson Universe: Past, Present & Future – slide 25 / 92 Northeastern Illinois Why are astronauts weightless in space? University
c 2012-2018G. Anderson Universe: Past, Present & Future – slide 26 / 92 Northeastern Illinois Newton’s Law of Gravitation University
Newton’s Law of Universal Gravitation (1687).
M2 Gravitational force: F M1M2 F = G 2 d d Universal Gravitational constant: F 11 2 2 M1 G =6.67 10− Nm kg− × m , m : masses of two bodies in kilograms (kg). • 1 2 d: distance between m and m in meters (m). • 1 2 F force between bodies in Newtons (N). •
c 2012-2018G. Anderson Universe: Past, Present & Future – slide 27 / 92 Northeastern Illinois Tides and the Moon University Mm F = G r2 Moon’s gravitational attraction: weaker
Low Tide
High High Tide Tide
Low Tide Moon’s gravitational attraction: stronger
Tidal bulges toward and away from Moon • High tide occurs 50 min later each day. •
c 2012-2018G. Anderson Universe: Past, Present & Future – slide 28 / 92 Northeastern Illinois Spring and Neap Tides University
Spring Tides
to Sun
New Moon Full Moon
c 2012-2018G. Anderson Universe: Past, Present & Future – slide 29 / 92 Northeastern Illinois Spring and Neap Tides University
Third Quarter Neap Tides
to Sun
First Quarter
c 2012-2018G. Anderson Universe: Past, Present & Future – slide 29 / 92 Northeastern Illinois Electromagnetic Spectrum University
Region Wavelength Frequency(Hz) Radio m – 10 cm 0 – 3 109 ∞ × Microwave 10 cm – 0.1 mm 3.0 109 – 3 1012 × × Infrared 0.1 mm – 0.7 µm 3.0 1012 – 4.3 1014 × × Visible 700 nm – 400 nm 4.3 1014 – 7.5 1014 × × Ultraviolet 400 nm – 1 nm 7.5 1014 – 3 1017 × × X-Rays 1 nm – 10−2 nm 3 1017 – 3 1019 × × Gamma-Rays 0 – 10−2 nm – 3 1019 ∞ ×
1 10−1 10−2 10−3 10−4 10−5 10−6 10−7 10−8 10−9 10−10 10−11 m λ Radio micro-waves IR UV X-rays γ-rays Hz f 108 109 1010 1011 1012 1013 1014 1015 1016 1017 1018 1019 1020
c 2012-2018G. Anderson Universe: Past, Present & Future – slide 30 / 92 Northeastern Illinois Electromagnetic Radiation University
Light is a wave of electric and magnetic fields. • The speed of light in vacuum is a constant. • c 3 108m/s ≈ × In general, light is composed of waves oscillating at • various frequencies (f). For each frequency component: c = λf • Light is composed of massless particles called photons. • The energy of a photon is:
E = hf
c 2012-2018G. Anderson Universe: Past, Present & Future – slide 31 / 92 Northeastern Illinois Electromagnetic Waves University
Light is a traveling wave of electric and magnetic fields: v = c E
x B
Wave speed = frequency wavelength: × c = fλ = λ/T
Speed of light in vacuum:
c = 299, 792, 458. m/s 3 108 m/s ≃ ×
c 2012-2018G. Anderson Universe: Past, Present & Future – slide 32 / 92 Northeastern Illinois Hydrogen Transitions University
continuous energy levels 0 n = −0.85 n =∞ 4 −1.51 n Paschen = 3 Series 3.4 n = 2 − Balmer Series Energy (eV)
13.6 n = 1 Lyman − Series
c 2012-2018G. Anderson Universe: Past, Present & Future – slide 33 / 92 Northeastern Illinois Blackbody Radiation University
Blackbody radiation: thermal radiation emitted by opaque bodies. (perfect absorbers)
Stefan-Boltzmann law for Luminosity:
4 L = σAT
Stefan-Boltzmann constant
8 2 4 σ =5.67 10− W/m K T = Temperature × · A = Area
c 2012-2018G. Anderson Universe: Past, Present & Future – slide 34 / 92 Northeastern Illinois Wein’s Displacement Law University
Hottest
Hotter
Intensity Hot
wavelength λ
Emission is a maximum at λm (Wilhelm Wien 1893)
−3 λmT = constant = 2.898 10 mK × c 2012-2018G. Anderson Universe: Past, Present & Future – slide 35 / 92 Northeastern Illinois University
Cosmic Address Our motion in the Universe
The Basics
Solar System Nebular Theory Collapsed Solar Nebula Composition Frost Line Formation Overview Summary Challenges Our Solar System Planets Terrestrial Planets Interiors of Terrestrial Plants The Earth’s Magnetic Field Reconstructed Temperature Record Global Temperature Anomaly (NOAA) Global Temperature c 2012-2018G. Anderson Universe: Past, Present & Future – slide 36 / 92 Anomaly Northeastern Illinois Nebular Theory University
Nebular Theory: Kant 1755, Laplace 1795 Our solar system formed from a giant cloud (nebula) of interstellar gas and dust. Denser regions of the solar nebula experienced stronger gravity and begin gravitational contraction. Heating, Spinning, Flattening The Rotational speed of cloud increased as it contracted due to • conservation of angular momentum: Collisions between particles in the collapsing nebula flattened it • into a flat disk with circular orbits. The nebula temperature increased as it collapsed due to • conservation of energy As the protoplanetary disk cooled, metal, rock and ice condense, coagulate and accrete into planetesimals and then planets.
c 2012-2018G. Anderson Universe: Past, Present & Future – slide 37 / 92
Northeastern Illinois Composition of the Solar Nebula University
TCondensation Abundance (by mass) H and He - 98% H Compounds < 150 K 1.4% Rock 500 1300 K 0.4% − Metals 1000 1600 K 0.2% −
H, He Hydrogen compounds include: 98% Rock & Metal: water (H2O) 0.6% • H compounds ammonia (NH3) 1.4% • methane (CH4) •
c 2012-2018G. Anderson Universe: Past, Present & Future – slide 39 / 92 TFrost 150 K T >TF T = TF T b b bb b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b Frost Line b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b bb b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b bb b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b bb b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b bb b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b bb b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b bb b b b b b b b b b b b b b b b b b b b b b b b b b b b bb b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b bb b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b 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b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b bb b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b bb b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b bb b b b b b b b b b b b bb b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b bb b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b bb b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b bb b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b bb b b b b b b b b b b bb b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b bb b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b bb b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b Rocky Planetesimalsb b b b Icy Planetesimals Gas Giants ⇒ Northeastern Illinois Formation Summary University Rock, metals, and ices condensed outside the frost • line, but only rock and metals condensed inside the frost line. Small solid particles collected into planetesimals that • then accreted into planets. Planets inside the frost line were made of rock and • metals. Additional ice particles outside the frost line made • planets there more massive, and the gravity of these massive planets drew in H and He gases. Solar wind blows away leftover gas • c 2012-2018G. Anderson Universe: Past, Present & Future – slide 41 / 92 Northeastern Illinois Challenges for the Nebular Theory University Surprises: Some massive planets orbit very close to their stars: “hot • Jupiters.” Some extrasolar planets have highly elliptical orbits. • Revisiting the Nebular Theory Nebular theory: Jovian planets should not form inside the frost • line (. 5 AU). The discovery of “hot Jupiters” has forced a reexamination of • nebular theory. Modification of the Nebular Theory Planetary migration or gravitational encounters may explain “hot Jupiters”. c 2012-2018G. Anderson Universe: Past, Present & Future – slide 42 / 92 Northeastern Illinois Our Solar System University Solar System c NASA Components The Sun Patterns • Inner Terrestrial Planets Patterns of Composition • • Outer Jovian Planets Patterns of Motion • • Asteroids and Comets • c 2012-2018G. Anderson Universe: Past, Present & Future – slide 43 / 92 Northeastern Illinois Planets University A planet is a moderately large object that orbits a star and shines primarily by reflecting light from its star. Following the 2006 IAU resolution, an object can only be considered a planet if: 1. It orbits a star 2. it is large enough for its own gravity to make it round. 3. It has cleared most other objects from its orbital path. An object which only meets the first two criteria is a dwarf planet. e.g. Pluto. c 2012-2018G. Anderson Universe: Past, Present & Future – slide 44 / 92 Northeastern Illinois Terrestrial Planets University Mercury Venus Earth Mars d⊙ REarth MEarth tilt T (K) Mercury 0.39AU 0.38 0.055 0◦ 700/100 Venus 0.72AU 0.95 0.62 177.3◦ 740 Earth 1.00AU 1.00 1.00 23.45◦ 290 Mars 1.52AU 0.53 0.11 25.2◦ 220 c 2012-2018G. Anderson Universe: Past, Present & Future – slide 45 / 92 Northeastern Illinois Interiors of Terrestrial Plants University Earth Venus Mars Mercury Moon Core Mantle Crust highest density medium density lowest density c 2012-2018G. Anderson Universe: Past, Present & Future – slide 46 / 92 Northeastern Illinois The Earth’s Magnetic Field University On the surface N S B N m N W E S S c 2012-2018G. Anderson Universe: Past, Present & Future – slide 47 / 92 Northeastern Illinois Global Temperature Anomaly (NOAA) University 1.0 bc bc NOAA Surface Data (Land + Marine) 0.8 bc bc bc bc bc bc bc bc bc bc bc bc bc 0.6 bc bc bc bc bc bc bc bc bc bc 0.4 bc bc bc bc bc bc bc bc bc bc bc bc bc bc bc 0.2 bc bc bc bc bc bc bc bc bc bc bc bc bc bc bc bc bc bc bc bc bc bc bc bc bc bc bc bc 0 bc bc bc bc bc bc bc bc bc bc bc bc bc bc (Degrees Celcius) bc bc bc bc bc bc bc bc bc bc bc bc bc bc bc bc bc bc bc bc bc bc bc bc T bc bc bc bc bc bc bc bc 0.2 bc bc bc bc bc bc bc bc bc bc ∆ bc bc − bc bc bc bc bc bc bc bc 0.4 bc bc bc − 0.6 − 1880 1900 1920 1940 1960 1980 2000 2020 Year c 2012-2018G. Anderson Universe: Past, Present & Future – slide 49 / 92 Northeastern Illinois Global Temperature Anomaly (NASA) University 1.0 bc bc NASA data, Hansen et.al. bc 0.8 bc bc bc bc bc bc bc bc bc bc 0.6 bc bc bc bc bc bc bc bc bc bc 0.4 bc bc bc bc bc bc bc bc bc bc bc bc bc bc 0.2 bc bc bc bc bc bc bc bc bc bc bc bc bc bc bc bc bc bc bc bc bc bc bc bc bc bc bc bc bc bc bc bc bc bc 0 bc bc bc bc bc bc bc bc bc bc bc bc (Degrees Celsius) bc bc bc bc bc bc bc bc bc bc bc bc bc bc bc bc bc bc bc bc bc bc T bc 0.2 bc bc bc bc bc bc bc bc bc bc bc bc bc bc bc bc bc Updated Nov. 2017 ∆ bc bc − bc bc bc bc bc bc bc 0.4 bc bc − bc bc 0.6 − 1880 1900 1920 1940 1960 1980 2000 2020 Year c 2012-2018G. Anderson Universe: Past, Present & Future – slide 50 / 92 Northeastern Illinois Jovian Planets University Jupiter Saturn Uranus Neptune 3 d⊙ R⊕ M⊕ ρ (g/cm ) tilt T (K) Jupiter 5.20 AU 11.21 317.9 1.33 3.1◦ 125 Saturn 9.54 AU 9.45 95.2 0.71 26.7◦ 75 Uranus 19.19 AU 4.01 14.5 1.24 97.9◦ 60 Neptune 30.06 AU 3.88 17.1 1.67 29.◦ 60 c 2012-2018G. Anderson Universe: Past, Present & Future – slide 52 / 92 Northeastern Illinois Jovian Densities University 1.5 ) Uranus and Neptune are denser 3 than Saturn because they have 1.0 proportionately less H/He. (g/cm ρ The greater mass of Jupiter com- 0.5 presses the planet. 0 Saturn Uranus Jupiter Neptune c 2012-2018G. Anderson Universe: Past, Present & Future – slide 53 / 92 Northeastern Illinois Tidal Heating University c 2012-2018G. Anderson Universe: Past, Present & Future – slide 54 / 92 Asteroids & Comets b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b Kuiper Belt b b b b b Asteroid Belt b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b bb b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b bb b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b bb b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b bb b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b Oort Cloud b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b Northeastern Illinois Asteroid Facts University Relatively small, rocky objects orbit- ing the Sun. Leftover rocky planetesimals • Majority between Mars and • Jupiter Total mass MMoon • ≪ Largest Ceres, d 950 km • ≈ 1.1 1.9 million with d> 1 km. • − > 400, 000 cataloged • Vesta c 2012-2018G. Anderson Universe: Past, Present & Future – slide 56 / 92 Northeastern Illinois Asteroid Orbital Classification University Asteroid Belt, 75% • (2.2 AU c 2012-2018G. Anderson Universe: Past, Present & Future – slide 57 / 92 Northeastern Illinois Meteors and Meteorites University Meteoroid: Small rocky debris from asteroid fragments or comet disintegration. Meteor: The flash of light produced when a meteoroid enters Earth’s atmosphere. Meteorites: Meteoroids that survive passage through the Earth’s atmosphere and impact on the ground. Most meteorites from the asteroid belt, some lunar and martian meteorites c 2012-2018G. Anderson Universe: Past, Present & Future – slide 59 / 92 Northeastern Illinois Meteoroid Summary University Most meteorites are pieces of asteroids. • Most meteor showers have their origins with • comets. Primitive meteorites are remnants from solar nebula. • Processed meteorites are fragments of larger bodies • that underwent differentiation. 106–107 kg of meteorites fall on Earth each year. • c 2012-2018G. Anderson Universe: Past, Present & Future – slide 60 / 92 Comet: A relatively small and ice-rich object that orbits a star Comet Hale-Bopp Northeastern Illinois Comet Summary University Icy left over planetesimals: Formed beyond the frost • line, comets are icy counterparts to asteroids. The nucleus of a comet is like a “dirty snowball.” • Most comets remain perpetually frozen in the outer • solar system. Most comets do not have tails, Only comets that enter • the inner solar system grow tails. Comets in plane of solar system come from the Kuiper • Belt. Comets on random orbits come from Oort Cloud. • c 2012-2018G. Anderson Universe: Past, Present & Future – slide 62 / 92 Northeastern Illinois University Cosmic Address Our motion in the Universe The Basics Solar System The Sun The Sun Structure Solar Structure Solar Fusion The Sun p-p cycle CNO cycle Solar Activity Solar Cycle Solar Cycle Stars Galaxies & Cosmology c 2012-2018G. Anderson Universe: Past, Present & Future – slide 63 / 92 Northeastern Illinois The Sun University 99.8% of solar system’s mass • Mostly H/He (plasma). • Converts 4 million tons of mass into • energy each second. R⊙ = 108R⊕ • M⊙ = 333, 000M⊕ • H 70% Sun Other He 28% Mass of Solar System Composition by Mass c 2012-2018G. Anderson Universe: Past, Present & Future – slide 64 / 92 Northeastern Illinois Solar Structure University Solar Wind: A flow of charged particles from the surface of the Sun. Extends beyond the orbit of Pluto. 6 Corona: R . 2R⊙, Outermost layer of solar atmosphere. T 10 K Very low density. Emits most of the Suns X-rays. ∼ Chromosphere: Middle layer of solar atmosphere T 104 105 −4 ∼ − K, ρ = 10 ρphot, 2,000 km thick. Radiates most of Sun’s UV. Photosphere: Visible surface of the Sun. Tave 6000 K ρ =2 10−7 g/cm3. ∼ × Convection zone: 0.7R⊙ c 2012-2018G. Anderson Universe: Past, Present & Future – slide 65 / 92 Solar Wind Corona Photosphere Convection zone Radiation zone Fusion Core Northeastern Illinois Solar Fusion University Hans Bethe: (1906-2005, Nobel Prize, 1967): The only two hydrogen fusing nuclear cycles which supply energy to stars: proton-proton cycle: T > 4 106 K. • × CNO cycle: T > 13 106 K. • × http://csep10.phys.utk.edu/astr162/lect/energy/cno-pp.html c 2012-2018G. Anderson Universe: Past, Present & Future – slide 67 / 92 Northeastern Illinois Proton-Proton Cycle University The proton-proton cycle: U(r) 1 1 2 + H+ H H+ e + νe (0.43 MeV) −→ 1 2 3 H+ H He + γ (5.49 MeV) −→ followed by either: 3 3 4 1 He + He He + 2 H+ γ (12.86 MeV), −→or 1 3 4 + H+ He He + e + νe −→ Net effect of the above reactions: 1 4 + ′ 4 H He + 2e +2νe + γ s (24.7 MeV) −→ c 2012-2018G. Anderson Universe: Past, Present & Future – slide 68 / 92 Northeastern Illinois CNO-I “carbon” Cycle University The Carbon Nitrogen Oxygen (CNO) cycle: Proposed independently by Hans Bethe and Carl von Weizs¨acker. CNO cycle is the main source of energy in starts heavier than the 6 6 sun. CNO begins to dominate at T = 17 10 K. T⊙ 15.7 10 K. Only 1.7% of 4He in the Sun is from CNO× cycle. ≈ × 12C 13N 1H + 12C 13N + γ +p − γ −→ − 13 + α β C+ e + νe − + p 1H + 13C 14N + γ + −→ 15N 13C 1H + 14N 15O + γ −→ + 15 + p + − N+ e + νe β γ − 1 15 12 4 H + N C + He +p − γ −→ 15O 14N Net effect of the above reactions: 41H 4He + energy −→ c 2012-2018G. Anderson Universe: Past, Present & Future – slide 69 / 92 Northeastern Illinois Solar Activity University Sunspots Visible dark, temporary spots on the Sun’s photosphere, caused by intense magnetic fields, which inhibits convection. Solar Flare Huge release of energy and sudden brightening on Sun’s surface. Giant exposion in Sun’s atmosphere. SF Emits charged particles. Solar Prominence filament, arc. Large, bright gaseous, Often loop shaped huge cloud of gas suspended y magnetic fields Coronal Mass Ejection The material which is ejected. Formed when prominences break apart. c 2012-2018G. Anderson Universe: Past, Present & Future – slide 70 / 92 Northeastern Illinois Solar Cycle University Solar Cycle (Solar magnetic activity cycle) The roughly periodic cycle over which the Sun’s activity changes. Changes include: solar radiation, ejection of solar material, number of sunspots, flares. Average duration of 11 years. c 2012-2018G. Anderson Universe: Past, Present & Future – slide 71 / 92 Northeastern Illinois University Cosmic Address Our motion in the Universe The Basics Solar System The Sun Stars Properties Bulbs m chart Stars Stellar Parallax Parsec Life of a Low Mass Star ≈ 1M⊙ Life of a High Mass Star (25M⊙) HR Diagram HR Diagram Clusters & HR Diagrams Galaxies & Cosmology c 2012-2018G. Anderson Universe: Past, Present & Future – slide 73 / 92 Northeastern Illinois Stellar Properties University Luminosity, from brightness and distance: 4 6 10− L . L . 10 L ⊙ ⊙ Temperature, from color and spectral type: 3, 000K . T . 50, 000K Mass, from binary systems: 0.08M . M . 150M ⊙ ⊙ Applet c 2012-2018G. Anderson Universe: Past, Present & Future – slide 74 / 92 Northeastern Illinois Brightness vs. Distance University 6 b = L 50 W 4πr2 5 L = b(4πr2) 4 r = L/4πb p 3 200 W 2 Brightness (b) 1 0 012345678910 Distance (r) c 2012-2018G. Anderson Universe: Past, Present & Future – slide 75 / 92 Northeastern Illinois Apparent Magnitude (m) University -30 Sun (-26.7) -25 -20 -15 Full moon (-12.6) -10 -5 Venus, at brightest (-4.4) 0 Sirius (-1.44) +5 Naked eye limit (+6) +10 Binocular limit (+10) +15 Pluto (+15) +20 +25 +30 Best Telescopes (+30) c 2012-2018G. Anderson Universe: Past, Present & Future – slide 76 / 92 Northeastern Illinois Stellar Parallax University b b b b b b b b b b b b b b Jan sky Jun sky Animation p d d(parsecs) = 1/p(arcseconds) 1 AU June January c 2012-2018G. Anderson Universe: Past, Present & Future – slide 77 / 92 Northeastern Illinois Parsec University Parsec: The distance at which a star has a parallax angle of one arc-second. One parsec (pc) is equal to 3.26 light-years. 1 distance (parsecs) = parallax angle (arc seconds) p Example: If p =0.04′′, 1 1 d = = = 25 pc p 0.04 c 2012-2018G. Anderson Universe: Past, Present & Future – slide 78 / 92 Northeastern Illinois Life of a Low Mass Star 1M University ≈ ⊙ 1. Collapsing Nebula to Protostar (30 million years) 2. Yellow main-sequence star: fusing hydrogen into helium primarily by the p-p cycle. (10 billion years) 3. Red Giant star: core hydrogen exhausted. Hydrogen fusion in a shell around inert helium core. (1 billion years) 4. Helium core fusion star (100 million years) 5. Double shell fusion red giant (30 million years) 6. Planetary Nebula (10,000 years) 7. White Dwarf (indefinite) c 2012-2018G. Anderson Universe: Past, Present & Future – slide 79 / 92 Northeastern Illinois Life of a High Mass Star (25M ) University ⊙ 1. Collapsing Nebula to Protostar (40,000 years) 2. Blue main-sequence star: fusing hydrogen into helium primarily by the CNO cycle. (5 million years) 3. Red Supergiant star: core hydrogen exhausted. Hydrogen fusion in a shell around inert helium core. (100,000 years) 4. Helium core fusion supergiant (1 million years) 5. Multiple shell fusion super giant (10,000 thousand years) 6. Supernova (months) 7. Neutron star or black hole (indefinite) c 2012-2018G. Anderson Universe: Past, Present & Future – slide 80 / 92 Northeastern Illinois Hertzsprung-Russell (H-R) Diagram University Temperature (K) 40,000 10,000 7,000 6,000 5,000 4,000 3,000 2,500 106 10 O B A b F G K M b − b b b b ( Magnitude Absolute b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b 4 b b b b b b b b b b b b b b b ) b b b b b 5 b b b b b b 10 b b b b b b b b b b b b b b b b b b b b b ⊙ b b b b b b b b b b b − b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b bb b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b bb bb b b bb b b b b b b L/L b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b bb b b b bb b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b bb b b b b b b b b b bb 2 b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b bb b b b b b b b b b b bb b b b b b b bb b b b b bb b b b b b b bb b b b bb b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b bb b b b b b b b b b b b b b b b b b b bb b b b b b b b b b b b b bb b b b b b bb b b b b b b b b b b b b b b b bb bb b b b bb b b bb b b b b b b b b b b b b b b b b b bb b b bb b b b b b b b b bb b b b b b b b b b b b bb b b b b b b bb b 0 b b b b b b b b b b b b b b b bb b b b b b b b b b b bb b b b b b b b b b b b b b b b b b b b b b b b b b 10 b b b b b b b b b b b b b b b b b b b b b b b b b b bb b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b bb b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b bb b b b b b b b b b bb b b b bb b b bb b b b b b b b b b bb b b b b b b b b b b b b b b b b b b b b b b b b b bbb b b b b b b b bb b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b bb b b b b b b b b b b b b b b b b b b bb b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b bb b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b bb b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b bb b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b bb b b b b b b b b b b b b b b b b b b b b b b b b b b b b bb b b bb b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b bb b b b b b b b b b b b b b b bb b b b b b b b b b b b b b b bb bb b b b b b b bb b b b b b b b bb b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b bb b b b b b b b b b b b b b b b b bb b b b b b bbb b b b b b b b b b b b b b b b b b b b b b b b bb b b bb bbb b b b b b b b b b b b b b b b b bb b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b bb b b b bb b b b b b b b b b b b b b b b b b b b b b b bb b b bb b b bbbb b b bb b b b b bb b b b b b b b b b b b b b b b b b b b b b bb b b bb b b b b b b b b b b b b b b b b b b b b b b bbb b b b b b b bb b b b b bb b b b b b b b b b b b b bb b bb b b b b b b bb bbb b b b bbb b bb b bb b b b b b b b b b b b b b b b b b b b b b bb bb b b b b b b b b b b b b b b b b bb bb b bbb b b b b b b b bb b bb bb b b b b b b b b b bb bb b b b b b bb bb b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b bb b b b b b b b bb b b b b b b b b bb b b b b b b b b bb b b b b b b b b b b b b b bb b b b b b b b b bb b bb b b b b b b b b b bb b b b b b b b b b b b b b b bb b b b b bb b b b b b b b b b b b b b b b b b b b b b b bb b b b b b b b b b b b b b b b b b b b b b b b b bbbb b b b b b b b b b b b b b b b b b bb b b b b b b b b b b b b b b b b b b b b b bb b b b b b b b b b b b b b b b b b b bb bb b b b b b b b b b b b b b b b b b b b b b b b b b bb b b b b b b b b b b b b b b b bb b b b b b b b b b b bb b b b b b b b b b b b b b b b b b b b b b bbb b b b b b b bb b b bbb b b b b bb b b b b b b b b b b b b b b b b b b b b bb b b b b b b b b bb b b bbb b b b b b b b b b b b b b b b b bb b b b b b b b b b b b b bb b b b b b b b bb bb b b b b b b b b b b bb b b b b b b b b b b b b b b b b b b b b b b b b b b b bb bb b b b b b 0 b b b b b b b b b b b b b b b b b b b b b b b b bb b b b b b b b b b b b bb b b b b b b b b b b b bb b b b b b b b b b b 5 b b b b b b b b 10 b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b M b b b b b b b b b Luminosity ( b b b b b b b b b b b b bb b b b b b b b b b b b b b b b b V − b b b b 2 b b b b b b b b b b b b bb b b bb b b b b bb b b b b b b b 10 b b b bb b b b b b b b b ) 10 b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b bb b b b b b b b b b b b b b b b b bb b b bb b b b b b b b b b bb b b b b bbb bb bb b b b b b b b bb b b b b b b b b bb b b b b b b b b b b bb b b b b b b b b b b b b − b b b 4 b b b b b b b 15 10 b b 0.5 0 0.5 1.0 1.5b 2.0 − Color Index (B V ) − c 2012-2018G. Anderson Universe: Past, Present & Future – slide 81 / 92 Northeastern Illinois Hertzsprung-Russell (H-R) Diagram University O B A F G K M 106 10 R Denebb R = 10 b = 1000 − R ( Magnitude Absolute ⊙ Rigel R Betelgeuseb ⊙ b b b 4 βCen Canopus Antares 5 ) 10 b R Spicab b ⊙ − b = Polaris R b Achernarb R ⊙ Bellatrix = 100 R b ⊙ L/L Regulusb Aldebaron b b 2 b b Arcturus Algol Vegab Capella 0 10 R b = 0 b Pollux . Sirius b Procyon 1R b ⊙ Altair αCenb A b 0 Sun 10 R b 5 = 0 αCen B . 01R ⊙ M Luminosity ( −2 V 10 Lalandeb 21185 10 b ) Sirius B Procyonb B Barnardsb −4 10 b 15 40,000 20,000 10,000 7,000 5,000 2,500 b Wolf 359 Temperature (K) c 2012-2018G. Anderson Universe: Past, Present & Future – slide 82 / 92 Northeastern Illinois University Cosmic Address Our motion in the Universe The Basics Solar System The Sun Stars Galaxies & Cosmology Distance Ladder Galaxies & Cosmology ISM Nebula Types Elliptical Spiral Galaxies Milky Way Dark Matter Halo Pie Chart Dark Matter Candidates c 2012-2018G. Anderson Universe: Past, Present & Future – slide 84 / 92 Northeastern Illinois Simplified Cosmic Distance Ladder University b Virgo Cluster LMC 1ly klyb Mly Gly b Hyades 3 SMC − ly b δ Cep b 10 b α Cen Cepheids Hubble’s Law stellar parallax b radar MS Fitting b SN-Ia solar nearby system Milky stars Way nearby galaxies Polaris b b Sgr A* b Pleiades Andromeda b Coma Cluster c 2012-2018G. Anderson Universe: Past, Present & Future – slide 85 / 92 Northeastern Illinois Interstellar Medium University Interstellar Medium (ISM): gas and dust between star systems in a galaxy (99% gas and 1% dust by mass). Gas composition: H 89% H 60% He 9% He 30% 2% Metals by number by mass Number density: n = 10−4 106 molecules/cm3 − n =0.5 molecules/cm3 c 2012-2018G. Anderson Universe: Past, Present & Future – slide 86 / 92 Northeastern Illinois Nebula Types University Nebulae are interstellar clouds of gas and/or dust. Origin: primordial hydrogen and helium gas, material ejected by stars (supernova remnants, planetary nebula, solar wind, ...), or any combination of the above. Catagorize by their interactions with visible light: Emission nebula are glowing clouds of interstellar gas. Reflection nebula reflect starlight without emitting visible energy of their own. Absorption nebula are dark clouds which obscure our vision of more distant light sources. c 2012-2018G. Anderson Universe: Past, Present & Future – slide 87 / 92 Northeastern Illinois Elliptical Galaxies University Elliptical galaxies only have a spheroidal component • (no disk component). Their shape ranges from spherical to cigar shaped. Similar to bulges of some spiral galaxies. Very little cool gas, very little active star formation. • Their red-yellow color indicates older, low-mass star population. Preferentially found in galactic clusters • Larger range of masses that other galaxy types • M = 107 1013M . − ⊙ c 2012-2018G. Anderson Universe: Past, Present & Future – slide 88 / 92 Northeastern Illinois Spiral Galaxies University Spiral galaxies are the most common galaxy type. Composed of: Disk: round, flat, thin, rotating group of stars, gas and dust with spiral arms. Stars of all ages. Spiral arms are locations of new star formation. Bulge: a large group of densly packed stars at the center of the galaxy. Some galactic bulges (classical) are like elliptical galaxies, others (pseudobulges) are similiar to the disk. Many if not all bulges contain supermassive black holes. Halo: extended spherical component, older stars with random orbits, very little gas, dust or star formation. Many halo stars are found in globular clusters. c 2012-2018G. Anderson Universe: Past, Present & Future – slide 89 / 92 Northeastern Illinois Milky Way Dark Matter Halo University Dark Matter Halo b b b b b b bb b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b bb b b b b bb b b b b b b b b b b b b b b b b b b b b b b b b b b Modern estimates: halo b b b b b b b b b b b b b b b b b b bb b b b b b b b b b b b b b b b b b b b b b b b b b b b bb b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b b mass 10 times the disk b b b b b b b b bb b b b b b b b b b b b bb b b b b b b b b b b b b b b bb b b b b mass. c 2012-2018G. Anderson Universe: Past, Present & Future – slide 90 / 92 Northeastern Illinois What is the Universe made of? University Dark Matter 24% Ordinary Matter 4.6%: ∼ Outside Stars: 3.8% Stars: 0.6% Dark Energy 71.4% ∼ The mass of dark matter in galaxies, clusters of galaxies, and the universe is five to six times the mass of ordinary matter. c 2012-2018G. Anderson Universe: Past, Present & Future – slide 91 / 92 Northeastern Illinois Dark Matter Candidates University MACHOS (Massive Compact Halo Objects): dead or failed stars - white dwarfs, neutron stars, black holes, brown dwarfs, Jupiters, .... Neutrinos νe, νµ, ντ . Lighter neutrinos would be an example of hot dark matter v c. Light and fast ≈ enough to escape a galaxies gravity. WIMPS (Weakly Interacting Massive Particles) M 100mp. WIMPS are cold dark matter (v c). ≈ ≪ Examples WIMPS include the Lightest Super Partner (LSP), sterile neutrinos, ... c 2012-2018G. Anderson Universe: Past, Present & Future – slide 92 / 92