NOTES: Section 24.1 Stars
Constellations
Groups of stars that seem to form a pattern
Constellations
Constellation seem to rise in the east and set in the west.
Some constellations are in the night sky during summer and day sky during winter.
Circumpolar Constellations
In the night and day sky all year
Have different positions in the night sky in summer and winter.
Seem to circle Polaris(the north star) during the night
Absolute and Apparent Magnitudes
Absolute light actually given off
Apparent light received on Earth
Distance reduces the light
Determining the Distances to Stars
Parallax Apparent shift in position of an object when viewed from two different positions.
The closer the object is to you the greater the apparent shift
Important in measurement
Used to measure distance to objects
Surveying triangulation
Distance to stars
Light-Year
Distance light travels in one year.
Speed of light
300,000 km/s
or
9.5 trillion kilometers/year
Proxima Centauri
Closest star to earth
4.2 light years from earth
How many kilometers?
Determining a Stars temperature and Composition
Colors of the electromagnetic spectra of a star
Temperature
Red cool
Blue - hot
Composition
NOTES: Section 24.2 The Sun
Layers of the Sun
Core
Radiation Zone
Atmosphere
The Suns Atmosphere
Photosphere light is given off, surface
Chromosphere
Corona
Surface features of the Sun
Sunspots dark, cooler areas on sun
Prominences huge arching columns of gas
Flares violent eruptions, can disrupt radio signals on earth
Our Sun: A Typical Star?
Average Star
Most Stars are Binarys
Two stars orbiting each other
NOTES: Section 24.3 Evolution of Stars
The H-R Diagram
Hertzsprung Russell Diagram graph showing the relationship between temperature and absolute magnitudes
Higher Temperature brighter the star
Size larger brighter
Main Sequence
Diagonal from top left to bottom right of H-R Diagram
Hot blue stars at top left
Cool red stars at bottom right
90% of all stars fall on the main sequence
Fusion
4 hydrogen nuclei fuse to form one helium nucleus
Einstein
E = mc2
Size of stars
Increasing mass, decreasing size
Red Giant
The Sun
White Dwarf
Neutron Star
Black Hole
Evolution of Stars
Nebula large cloud of gas and dust
Evolution of Stars
Nebula Protostar Main Sequence(like our Sun) Red Giant White Dwarf Black Dwarf
Nebula Protostar Main Sequence(100 times Suns Mass) Supergiant Supernova Neutron Star or Black Hole
"Stars are the birth places of all matter"
NOTES: Section 24.4 Galaxies and The Expanding Universe
Galaxies
Large group of stars, gas, and dust held together by gravity
The Milky Way
Our Galaxy
Classification of Galaxies
Elliptical shaped like football
Spiral arms like curved spokes of a wheel
The Milky Way
Irregular do not fit other classifications
Expansion of the Universe
Doppler Shift:
Squeezing(shorting) of waves as the wave source and destination move closer together
Higher pitched sound
Blue shift of light
Expansion of the Universe (cont.)
Doppler Shift (cont.):
Stretching(lengthen) of waves as the wave source and destination move farther apart
Lower pitched sound
Red shift of light
Red Shift
Edwin Hubble 1924 Red Shift of all galaxies
Distance galaxies show more Red Shift
Galaxies are moving away from each other
Expanding Universe
Big Bang
Big Bang
1. The explosion of the big bang sent all matter moving apart. With in fractions of a second, the universe grew from the size of a pin to 2000 times the size of the sun.
2. By the time the universe was one second old, it was a dense opaque, swirling mass of elementary particles.
Big Bang
3. As matter cooled, hydrogen and helium gas formed.
4. Matter began collecting in clumps and eventually formed into galaxies. Over one billion years after the initial explosion, the first stars were born
