Download Branches of Earth Science Tools Used to Study Stars Constellations

Chapter 21: Stars Notes
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Branches of Earth Science
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Astronomy: The study of planets , stars, and other objects in space .
Lithosphere: the land masses of earth
Hydrosphere: waters of the earth
Atmosphere: The envelope of gases that surround the Earth as well as space and
stars .
Tools Used to Study Stars
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Spectroscope: Breaks light from a distant star into its characteristic colors
o SPECTRUM: the band of colors that forms as light passes through a prism
o Used to see if galaxies are moving away or toward the earth
Telescopes: device that makes distant objects appear closer
Types of Telescopes
o Optical
o Radio
o X-Ray
o U-V
o Infrared
Constellations
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Constellations: group of stars that formed patterns
Different cultures gave different names to the constellations
o Greeks named constellations according to myths
Importance of Constellations
o Navigation
 Sailors use Polaris (North Star)
 Important in space navigation
o Used to predict weather
Best Known Constellations
o Big Bear or Ursa Major
 Has pointer stars to Polaris
o Little Bear or Ursa Minor
Characteristics of Stars
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What are stars like?
o Stars are made up of mostly hydrogen
o Stars produce energy through nuclear fusion .
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There are 4 characteristics of starts that scientists use to Classify stars
o Color & Temperature
o Size
o Composition
o Brightness
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Color and Temperature
o A stars color reveals its surface temperature
 The surface temperature is lower than the core temperature due to
nuclear fusion.
o Stars are very Patriotic when it comes to color
Coldest
Red
White
Hottest
Blue
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Size
o 5 Types or Categories
o Smallest
Neutron (16-20 km diameter)
 White dwarf (size of Earth)
 Medium Size (the sun) *MOST STARS *
 Giant (10-1000 x’s the sun)
o Largest
Super Giant (1000 x the diameter of the sun)
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Composition (Chemical Makeup)
o Most stars have the same general composition
 73% Hydrogen
Most Common
 25% Helium
2nd most common
 2% Other Elements
o Scientists use a spectroscope to identify characteristics
 Characteristic: Something that identifies an object
 Elements have “Fingerprint” color characteristics
 They have a unique set of lines in the spectrum
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Brightness (Also called Magnitude)
o Depends on…
 Temperature
 Size
 Distance
o Apparent Brightness: the brightness of a star as it appears on Earth.
o Absolute Magnitude: The amount of light the star actually gives off
Measuring Distance to Stars
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Light Year- Astronomers use light years to measure the distances between stars
o A light year is the distance that light travels in one year
 9,460,730,472,580.8 km
 5,878,630,000,000 miles
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Parallax- the apparent change in the position of a star in the sky.
o The change is due to the change in the Earth’ position as the Earth revolves
around the sun.
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Hertzsprung-Russell Diagram: (H-R Diagram)
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It is a scatter plot
Shows the relationship between absolute brightness and surface temperature
This is the single most important diagram that astronomers use
Uses
o Classify Stars
o Understand how stars change over time
Bright
Absolute
Magnitude
Dim
Hottest
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Surface Temp
Main sequence: the area where the most stars are located
o Extends from the upper left corner to the lower right corner
o 90% of stars are located here.
Coolest
Lifecycle of Stars
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Nebula (large cloud of gas and dust) forms protostar with gravity
o Nuclear Fusion (atoms combine to form heavier atoms)
o Lower Mass Stars
 Giant Star: outer layer expands
 White Dwarf: extremely dense
 Black Dwarf: dead
o Higher Mass Stars
 Super Giant: Fusion continues until iron is formed
 EXPLOSION: No more nuclear fusion
 Super Nova: star breaks apart
o Neutron Star
o BLACK HOLE
Life Cycle of a Star
Average Star
Red Giant
Planetary Nebula
White
Dwarf
Neutron Star
Stellar Nebula
Massive Star
Red Super Giant
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Supernova
Black Hole
Deaths of Stars: when a star begins to run out of fuel , its core shrinks and its
outer portion expands
o White Dwarf
o Neutron Star
o Black Hole
Multiple Star Systems
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Multi Star System: Star system with one or more companion stars
Most stars have companions but not all stars
o The sun does not have a companion
 The sun is the closest star to the earth
o Binary Stars: Star systems with two stars (Bi=2 – remember bicycle)
Eclipsing Binary Star System
o The larger companion blocks the smaller companion
Star Clusters
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Star Clusters: large groupings of stars
o Open Cluster
 Loose and disorganized appearance
 Contain few hundred to 1000 stars
 Young stars
o Globular Cluster
 more common round , densely packed stars
 100,000 to 1,000,000 stars
 older stars
Galaxies
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Galaxy is a huge collection of stars bound by gravity
o Contain various star groups
Billions of galaxies in the universe
3 types of galaxies
o Spiral
o Elliptical
o Irregular
The Milky Way
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The galaxy we live in
Spiral shaped
Looks like a milky or whitish band in the sky
Sun is located in one of the spiral arms
It has 400 billion stars
It takes the sun and planets over 200 million years to move around the center of
the milky way
Big Bang Theory
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Theory is an idea that is supported by evidence
The universe began to expand with the explosion of concentrated matter and energy
and has been expanding ever since