Download Parallax

Constellations
Constellations
 Patterns in the sky
 Represent Mythical Characters, Animals or
Objects
 Examples


Big Dipper (Ursa Major), Little Dipper (Ursa
Minor), Orion
Circumpolar
• Meaning they stay above the horizon all year long
Big Dipper
Little Dipper
Orion
Properties of Stars’ Brightness
Absolute Magnitude
 Is a measure of the light that a star gives
off
Apparent Magnitude
 Is a measure of the amount of light that is
received on Earth
Why the Two Measurements
 Is
helps us classify stars
 Helps us measure distances to stars
Here’s How
 Luisa
conducted an experiment to
determine the relationship between the
distance and the brightness of stars. She
placed a light bulb at different distances
along a meter stick and measured the
brightness of the light with a light meter. On
next side you will see Luisa’s data.
 What trends do you notice?
 What is the relationship between light
intensity and distance?
Luisa’s Data Table
Effect of Distance on Light
Distance (cm)
Meter Reading (luxes)
20
4150.0
40
1037.5
60
461.1
80
259.4
Space Measurement
Parallax
 Astronomers measure the apparent shift in
its position when viewed from two different
angles
 Light Year


Because of the vast dimensions of space we
use Light Years when calculating Distances
Light travels at 3.00 x 10^8 m/s
• How far does it travel in one year?
Parallax
Star Properties
 Color




Indicates Temperature
Hot stars are blue/white
Cool Stars look orange/red
Yellow Stars indicate medium temperature
• Our Sun is a medium temperature star
Star Properties
 Spectrum



View Star light with a spectroscope you can
break up the visible light into a “fingerprint”
Spectrum indicates elements in the star’s
atmosphere
Spectrum gives the following info:
•
•
•
•
Temp
Pressure
Density
Motion of the Star’s Gases
Classifying Stars
Ejnar Hertzsprung and
Henry Russell
 Graphed Stars by
Temperature and
Absolute Magnitude
 Called it the H-R
Diagram
H-R Diagram
Main Sequence (MS)
 Diagonal Band
 Upper Left


Lower Right


Cool, Red, Dim Stars
Middle


Hot Blue. Bright Stars
Average Yellow Stars
Dwarfs and Giants

10% of Stars that
Don’t Fit on MS
Production of Energy
Nuclear Fusion
 Joining of Atoms
 Proton – Proton
Chain


Starts with two
Protons and Ends with
Helium
ENERGY
Stellar Evolution
Stellar Evolution
Nebula contraction
1.


Temperature increase
At 10 million Kelvin Fusion Begins
Balancing of Heat and Pressure
2.





This is Called steady State Equilibrium
Balance is lost when Hydrogen Core is used up
Core contracts and heats up causing outer
layers to expand and cool
Star becomes a giant
Helium nuclei fuse to form a core of Carbon
Stellar Evolution
White Dwarf
3.


Helium is exhausted and outer layers of giant
escape
Core contracts into a hot dense star
Supergiants
4.



Massive stars causes higher temps and greater
expansion
Fusion stops
Core crashes inward causing the outer part to
explode into a Supernova
Stellar Evolution
Collapsed Core of a Supernova may form
a neutron star of extremely high density
A Tremendously Big Supernova Core can
collapse to a point of no Volume – a Black
Hole
5.
6.


Gravity is so strong not even light can escape
Beyond the Event Horizon gravity operates as
normal
Interstellar Nursery
Life Cycle of Our Sun
1987 Super Nova




http://aspire.cosmicray.org/labs/star_life/starlife_main.html
http://btc.montana.edu/ceres/html/LifeCycle/stars1.html#
activity2
http://www.ioncmaste.ca/homepage/resources/web_reso
urces/CSA_Astro9/files/multimedia/unit2/star_lifecycle/st
ar_lifecycle.html
http://chandra.harvard.edu/resources/misc/speci
al_features.html
Black Hole