Download ν - Luleå tekniska universitet

Astrophysics
&
Cosmology
Erik Elfgren
Luleå
Civilingengör
Exchange student
Luleå tekniska universitet
École polytechnique
Msc Physics
Summer job
Summer student
Cavendish laboratory
CERN
Université de Montréal
• Dust
CMB
light
Star
light
1st
stars
Supernova
Dust
Dust
emission
Planck
detector
• Detection with Planck satellite?
CMB
Angular
correlation
Local dust
Planck noise
Early dust
180º/angle
• Preons
n
He
p
u
d
β δ
Proton
Quark
p
u
n
Atom
Nucleus
β
(βδ) (αδ) (αβ) (βδ) (αδ) (αβ)
α
β
δ
Z*
α
νe
μ+
ντ
u
s
c
Z0/Z’
W+
β
e-
νμ
τ-
d
X
b
W-
Z’/Z0
W’- β
δ
νκ1
κ+
νκ2
h
k
t
Z*
W’+
Z”
Leptons
Quarks
Force carriers
α
δ
• Heavy neutrinos
Gamma ray
intensity
N
N
Lecture 1
Overview
Orion nebula
What is science?
To understand the universe, astrophysicists use the laws of
physics to construct testable theories and models.
Scientific method
• Based on observation, logic, and skepticism.
Hypothesis
• A collection of well thought- out ideas to explain a
phenomenon
Model
• Hypotheses that have withstood observational
and experimental tests.
Theory
• A well- founded body of related hypotheses
and models that form a self- consistent
description of nature.
Astrophysics
The solar system
Our Sun
Terrestrial Planets
Mercury, Venus, Earth,
Mars
Asteroid Belt
Small rocky bodies
Gas Giant Planets
Jupiter, Saturn, Uransus,
Neptune
Kuiper belt
Belt of icy objects
Terminal shock
Protects the solar system
Oort cloud
Ice rocks (50 000 AU)
Astrophysics
Stars
A large, glowing ball of gas that generates
heat and light through nuclear fusion
Astrophysics
Planets
A moderately large object which orbits a star; it shines
by reflected light. Planets may be rocky, icy, or gaseous
in composition.
Dwarf planets
Pluto, Ceres, Eris
Astrophysics
Moons
Objects which orbits a planet
There are about
100 known moons
in the solar system
Astrophysics
Asteroids
Small and rocky objects that orbit a star
A few hundreds of
kilometres in diameter
down to rocks just tens
of metres.
The Patroclus system, near Jupiter
Astrophysics
Meteroids
Rocky objects (<10m) in the solar system
A few hundreds of
kilometres in diameter
down to rocks just tens
of metres.
The Barringer Crater
Astrophysics
Comets
Small and icy objects with a coma that orbit a star
The coma is the
nebulous envelope
around the nucleus of a
comet
Halley’s comet
Astrophysics
Nebula
An interstellar cloud of gas and/or dust
Planetary nebulae
The gaseous shells ejected
from low-mass giant stars
when they transform into
white dwarfs
Protoplanetary nebula
Just before planetery
nebula
Supernova remnants
Leftovers after supernovae
Astrophysics
Galaxies
A great island of stars in space, all held together by
gravity and orbiting a common center
Most galaxies seem to
have a giant black hole
in their center
The Milky way
Astrophysics
Distances
• Light travels with a finite speed
• It takes
 8 minutes to reach us from the Sun
 8 years to reach us from Sirius (8 light-years away)
 1,500 years to reach us from the Orion Nebula
• The farther out we look into the Universe, the farther
back in time we see!
• The universe is 13.7 × 109 years old
13.7 × 109 ly away (and counting!)
we can see
Astrophysics
Distances
• Distances are measured in light-years (ly) or parsecs (pc)
 1 ly = 9.4605284 × 1015 m
 1 pc = 3.08568025 × 1016 m ≈ 3.26 ly
• Small distances are measured in astronomical units (AU)
 1 AU = 3.08568025 × 1016 (1.496 × 108 km)
• Cosmic distances are often measured in redshift, z
Astrophysics
Angles
Astrophysics
Angles
Astrophysics
Small angles
1º = 60 arcminutes = 60’
(bågminuter)
1’ = 60 arcseconds = 60”
(bågsekunder)
Example:
On January 1, 2001, the
planet Saturn had an
angular diameter of
19.7” as viewed from
Earth.
Proxima Centauri has
a parallax of 0.77”
Astrophysics
Small angle approximation
D = 2 d tan(X·π/1,296,000)
≈ X·d/206,265
where X is the angular size (in arcseconds),
D is the linear size of the object and
d is the linear distance to the object.
Astrophysics
Solar constants
• The Sun is denoted by the symbol 
• The mass of the Sun is
 M = 1.9891×1030 kg
• The luminosity (=emitted electromagntic energy) is
 L = 3.846×1026 W
• These are often used as units of measurement
for celestial bodies, e.g. the mass of the black hole
in the center of the Milky way has a mass of 3.7×106 M
Astrophysics
The Milky way
300 109 stars, 0.1 Mly, 5.8 1011 M
Astrophysics
The local group
3 galaxies, 37 dwarf galaxies, 10 Mly, 1012 M
Astrophysics
The Virgo supercluster
100 groups, 2000 galaxies, 200 Mly, 1015 M
Cosmology
The Millennium simulation
Evolution of the universe with 1010 particles
Cosmology
The Expanding Universe
The “fabric” of the space expands
Cosmology
The Big Bang
• Happened some 13.7 ×109 years ago
• The first atoms (H and He) formed in the first 3 minutes
• The universe expanded and cooled quickly
• The theory was “proven” by the Cosmic Microwave
Background
Cosmology
The Cosmic Microwave Background
• Was released some 400,000 years after the Big Bang
• Is an almost perfect Black-body radiation with
temperature 2.73 K
• Is isotropic to a factor 10-5
• The tiny fluctuations tell us about the structure of the
universe
• Is the single most powerful tool in cosmology
Cosmology
Energy and Matter in the Universe
• 1% is in stars and gas
• 5% is ordinary matter
• 25% is dark matter
• 70% is dark energy