Transcript Stars - Independence High School

Stars
Chapter 25
The Sun
• The Sun’s mass controls the
motions of the planets
• Less dense than Earth
• High pressure and
temperature causes gases to
be plasma
• Fusion- Combining of
nuclei to form a larger nucleus
• Fission- Separation of large
nucleus into smaller nuclei
• The Sun uses fusion to
combine Hydrogen into
Helium
Anatomy of the Sun
1.
Core- The Sun's
nuclear
"furnace," where
fusion reactions
initially combine
hydrogen atoms
to produce
helium, yielding
energy in the
process.
Anatomy of the Sun
2. Radiative
Zone. Energy
moves through
a surrounding
envelope of
gas toward the
Sun's surface.
Anatomy of the Sun
3. Convection
Zone. Big
"bubbles" of
hot gas
transport
energy to the
surface.
Solar Zones
• Radiative Zone- 61%
of interior from core.
Heat moves directly to
the surface
• Convective Zone- 14%
as heat moves to
surface and cools,
matter becomes more
dense and sinks to be
reheated
Anatomy of the Sun
4.PhotosphereThe Sun's
visible
surface.
Because of its
high
temperature,
it glows
yellow.
• Photospherelowest layer
of the
atmosphere
• 400 Km thick
• Visible
surface
• Chromospheresecond layer
• 2500 KM thick
• 30000° K
• Normally not
visible
Anatomy of the Sun
7. Corona- The
Sun's outer
atmosphere,
which is heated
by the magnetic
field to millions
of degrees.
• Corona- The
outermost
layer
• Several million
kilometers
thick
• 1 to 2 million
degrees K
• Low density
Solar Wind
• Charged particles escaping
from the corona
• Reaches Earth at 400 km/s
• Particles collide with
atmospheric gases to form
auroras
Solar Activity
• Sunspots- Dark colored, cooler spots on
the surface of the photosphere; caused by
magnetic fields
• Coronal Holes- Low density gas areas of
the corona usually over sunspots; provide
escape for solar wind
Solar Activity
• Solar Flares- Eruptions of particles and
radiation from the surface of the Sun; can
cause problems with Earth’s communication
systems
• Prominence- An arc of gas that is
emitted from the chromosphere or
condenses in the corona; 50000° K
Solar Activity Impact
•
•
•
•
Solar activity cycle lasts 22.4 years
11.2 to maximum sunspots
11.2 to minimum sunspots
Low sunspot activity cause a cooling
of the Earth’s climate (Maunder
Minimum)
Spectra
• Visible light arranged by wavelength
• Continuous- No breaks in the band
• Absorption- Bands caused by chemicals
in the atmosphere absorbing certain
wavelengths
• Emission- Bright lines from a gas at
certain wavelengths
Star Groups
• Constellations- groups of stars; usually
named animals, mythological characters, or
everyday objects
• Circumpolar- Orbit the poles and can
be seen year round
• Seasonal- Orbit equator and can only be
seen during certain times of the year
Star Groups
• Clusters- Group
of stars that are
gravitationally
bound; open or
globular
• Binaries- Two
stars gravitationally
bound together;
appear as one to the
human eye. One is
brighter than the
other
Star Light, Star Bright
• Apparent Magnitude- The brightness
of a star to the naked eye, regardless of
distance from Earth.
• Absolute Magnitude- Brightness of
stars measured at equal distances
• Luminosity- Amount of energy per
second put out by a star.
Star Measurement
• Light Year- The distance the light will
travel in a year = 9.461 X 10¹² km
• Parsec- 3.26 light years = 3.086 X 10¹³
km
• Parallax- Apparent shift in position
caused by the motion of the observer
Star Classifications
• O, B, A, F, G, K, M- Based on spectral lines
and temperature
• O has hottest temperature and fewest lines
• M has coolest temperature and most lines
• Each letter is divided into 9 numbered
categories
Star Structure
• 73% Hydrogen
• 25% Helium
• 2% Other
Life Cycle
• Star Formation- Cloud of
interstellar gas called a Nebula
which forms a Protostar
• Protostar becomes hot enough
for fusion to begin and become
a star
Life Cycle
• Red Giant- Hydrogen is used up and
star expands and cools; gases start to
escape
• Core of red giant is hydrogen and
convert to carbon
• Star shrinks and becomes White
Dwarf
• White Dwarf does not require heat
source to continue
Life Cycle
• Neutron Star- Large cores collapse in on
themselves
• Supernova- Center of neutron star auses
massive explosion blowing off the outer
layers
• Black Hole- Massive core that collapse in
and with a gravitational field that sucks
everything in.