Download stars

EXPLORING THE UNIVERSE
Chapter 26
26.1 Energy From
the Sun
REVIEW OF VOCABULARY
• Core - central
region, where
nuclear fusion
occurs.
HOW DOES THE SUN
PRODUCE ENERGY?
Energy is produced in its central region by the fusion of
hydrogen nuclei into helium nuclei.
QUESTION: WHAT NEW
ISOTOPE IS PRODUCED BY
THIS FUSION REACTION?
1.
hydrogen-1
2.
helium-4
3.
oxygen-16
4.
none
WHAT NEW ISOTOPE IS
PRODUCED BY THIS FUSION
REACTION?
1.
hydrogen-1
2.
helium-4
3.
oxygen-16
4.
none
26.1 FORCES IN BALANCE
May the force be with you!
WHY DOES THE SUN REMAIN
STABLE OVER TIME?
• Inward pull of
gravity balances the
outward push of
thermal pressure
from nuclear fusion.
QUESTION: WHAT WOULD
HAPPEN TO THE SUN IF IT
BEGAN TO RUN OUT OF FUEL?
1.
It would become cooler very quickly.
2.
The force of gravity would decrease.
3.
Its core would expand as thermal pressure increased.
4.
Its core would shrink as thermal pressure decreased.
WHAT WOULD HAPPEN TO THE
SUN IF IT BEGAN TO RUN OUT
OF FUEL?
1.
It would become cooler very quickly.
2.
The force of gravity would decrease.
3.
Its core would expand as thermal pressure increased.
4.
Its core would shrink as thermal pressure decreased.
26.1 THE SUN’S INTERIOR
INTERIOR FACTS
• The sun’s interior consists of 3 parts.
• Core
• Radiation zone
• Convection zone
• Energy moves through the sun in two main ways:
• Radiation
• Convection
REVIEW OF VOCABULARY
• Radiation zone - region of highly compressed gas where
energy is transferred by the radiation.
REVIEW OF VOCABULARY
• Convection zone the outer layer of the
sun's interior, where
energy is
transferred mainly
by convection
currents.
REMEMBER HOW
CONVECTION CURRENTS
MOVE…..
26.1 THE SUN’S
ATMOSPHERE
Very unlike Earths!
EXTERIOR FACTS
• The sun's atmosphere consists of three layers.
• Photosphere
• Chromosphere
• Corona
These regions are outside the convection zone.
PHOTOSPHERE
• Innermost layer
• Visible surface of the sun
• 500 kilometers thick
• Temp: approximately 5800 K
CHROMOSPHERE
• Middle layer
• Temp: increases to nearly 10,000 K
• At high temperatures, hydrogen gas emits a reddish light.
• This light gives it its name, which means “sphere of color.”
• Can see this during a total solar eclipse.
CORONA
• Outermost layer
• Gases in the corona are thin
• Temp: Gases super hot (about 1 million K)
• Thermal energy in it is relatively small.
• Usually seen only during solar eclipses.
26.1 FEATURES OF THE
SUN’S ATMOSPHERE
SUN HAS GOT A MAGNETIC
PERSONALITY!
• The sun's magnetic field produces striking features on and
above its surface
• Such as:
• Sunspots
• Prominences
• Solar flares.
SUNSPOTS
• Areas of gas in the photosphere that are cooler than
the surrounding gases.
• Spots can be larger than Earth
• Associated with intense magnetic fields on the sun.
• Last from a few hours to a few months.
• Numbers varies in cycles, with about 11 years
separating one sunspot peak from the next.
PROMINENCES
• Huge loops of gas that erupt from sunspot regions.
• Extend from the photo S into the chromo S and sometimes into
the corona.
• Travel along the magnetic field lines that connect sunspots.
• Heights can be more than 100,000 kilometers above the sun's
surface.
SOLAR FLARES
• Sudden release of energy
• Surface erupts dramatically, producing X-rays and
hurling charged particles into space.
• Heat the corona to a temps near 20 million K and
produce solar wind.
• High-energy particles and radiation can reach Earth
• Cause magnetic storms in Earth's upper
atmosphere.
• Storms disrupt electric power transmission, radio,
TV, and phone signals.
QUESTION: HOW CAN SUNSPOTS
BE RECOGNIZED ON THE SUN'S
SURFACE?
1.
Sunspots appear darker than the surrounding photosphere.
2.
Sunspots appear lighter than the surrounding photosphere.
3.
It is hard to distinguish sunspots from the surrounding
photosphere.
4.
Sunspots always appear in definite groups.
HOW CAN SUNSPOTS BE
RECOGNIZED ON THE SUN'S
SURFACE?
1.
Sunspots appear darker than the surrounding photosphere.
2.
Sunspots appear lighter than the surrounding photosphere.
3.
It is hard to distinguish sunspots from the surrounding
photosphere.
4.
Sunspots always appear in definite groups.
26-2 STARS
STARS
• Star-a large, glowing
ball of gas in space,
which generates
energy through
nuclear fusion in its
core.
• the sun is the closest
star to Earth
DISTANCES
• Astronomical Unit(AU) distance from
Earth to the Sun~
(150,000,000Km)
• Most of Space is
empty, so huge
distances are
required.
• Light Year-distance
light travels in 1 year.
• Approx. 9.5 trillion Km
(at 300,000 Km/s)
• 1 light year=63 AU
PARALLAX
• Apparent change in
position of an object
with respect to a
distant background.
• How we measure the
distance of stars
• Greater
parallax=closer star
• Winter to Summer
PROPERTIES OF STARS
• Color &Temperature
• The color of a star
indicates its surface
temperature( think
color spectrum)
• Brightness
• closer you are to a
light the brighter it
appears( not always)
• Apparent brightnessbrightness appears
from Earth
• Absolute brightnesshow bright the star
really is
• Can be calculated
using distance (if
known)
STAR PROPS. CONT’
• Size &Mass
• Diameter can be
calculated using
temp, and brightness
• Mass can be
calculated using
gravitational
interactions
• Composition-what is
it made of
GIANTS AND DWARFS
• Giants- large,
bright stars that are
smaller and fainter
supergiants
• White dwarfs- small
dense remains of a
low-medium-mass
star.
HERTZSPRUNG -RUSSELL
DIAGRAM
26-3 LIFE CYCLE OF STARS
• Stars change over their lifespan just like animals change
throughout their life.
• Nebula-a large cloud of gas and dust spread out over a large
volume of space.
• They can have different appearances bright or dark
STARS
• Stars are created due to
gravity.
• Contacting clouds of
gas/dust with enough
mass to form a star are
called protostars.
• Stars are formed when
contracting of gas/dust
become so dense/hot that
nuclear fusion occurs.
ADULT STARS
• Most of a stars life is in
the main sequence on
the H-R Diagram.
• Mass determines how
long it stays in this
sequence.
• More mass=brighter
stars, but they use up
fuel quicker.
DEATH OF A STAR
• When a star runs out
of fuel (Hydrogen),
gravity overtakes the
star.
• The core cools
• Temperatures rise,
causing swelling on
exterior.
• The dwindling supply
of fuel in a star’s core
ultimately leads to the
star’s death as a white
dwarf, neutron star, or
black hole.
DYING STARS
• Planetary nebulaglowing cloud of gas
surrounding a dying star.
(low mass)
• Supernova-collapse of
outer layer of dying high
mass star, huge
explosion producing
more light than the entire
galaxy generates
EVOLUTION OF STARS
DYING STARS
• Neutron Star-remnants of high-mass star that has exploded
supernova.
• Spinning neutron stars that give off strong pulses of radio
waves are called pulsars.
• Black Hole-an object whose surface gravity is so great that
even electromagnetic waves cannot escape it.
26-4 GROUPS OF STARS
• Constellation-group of
stars that appear to
form a pattern.
• Star System-group of
2 or more stars held
together by gravity.
• Almost ½ stars are star
systems.
• Binary star(2)
• Star Clusters
• Open clusters
• Associations
• Globular clusters
• Open-disorganized &
loose appearance
• Associationstemporary clusters of
young stars
(eventually move
apart)
• Globular-large group
of older stars, appear
like a dense
concentration
GALAXIES
• A huge group of
individual stars,
star systems, star
clusters, dust and
gas bound
together by
gravity.
• Milky Way
• Billions of
galaxies in the
universe
GALAXIES
• 4 main types:
• Spiral-bulge of stars at
the center with arms
extending out like a
pinwheel
• Milky Way
• Barred-Spiral-bar
through the center with
arms extending out to
the sides
• Elliptical-spherical or
oval with no arms
• No new stars due to low
amounts of dust and gas
• Irregular-have a
disorganized
appearance
• Many young stars due to
high dust and gas
content
GALAXIES
MILKY WAY
• 200-400 billion stars
• Every star you see in
the sky is in our
galaxy
• 100,000 light yrs in
diameter
• Our solar system
located in an arm of the
spiral.
• Takes 220 million yrs.
For the sun to orbit
the galaxy
EXPANDING UNIVERSE 26-5
HUBBLE’S LAW
• As waves move
towards you
wavelength gets
shorter (blue), as it
moves away it gets
longer (red)-think
Doppler.
• Larger change=more
speed
• Red Shift- shows most
galaxies light is
turning red=they are
moving away from
Earth
• Further galaxies are
moving away faster
than closer
galaxies=more shift
• Hubble’s Law
THE BIG BANG THEORY
• Astronomers theorize that the universe came into being at a
single movement.
• Once it was a hot dense small region
• Began in an instant billions of years ago (explosion)
• The universe expanded quickly, then quickly cooled down.
• Gravity caused the formation of stars/galaxies.
• The sun formed 4.6 billion years ago when the universe was 2/3rds the
present size.
BIG BANG
• Evidence
• 1965 2 physicists noticed a
radio signal from every
direction
• Cosmic microwave
background radiation
• Cosmic microwaves and
the red shift strongly
support the Big Bang
Theory
• Dark Matter-matter that
doesn’t give off radiation
• Cannot be seen but
effects of gravity can be
noticed.
• Age of the Universe is
approximately 13.7 billion
yrs. Old.
• What NEXT?
• Expansion?
• Contraction?
• Bounce?