Card Set Information
Astro Exam 2
What is a wave?
a wave traveling disturbace that moves energy without moving mass
What is frequency?
Number of times wave repeats its self per second.
1. 400 nm to 700 nm
Oncoming is shorter, outgoing is longer
Radial velocity 2
Wave goes towards person blue shifted and shorter. Wave goes away longer and red shifted.
All waves length that are present and how much are present at each wave length.
Atmosphere and light 3
1.More likely to scatter shorter wave lengths.
2.Blue light will scatter 60x more than red light.
3.Person behind equals unscatter, People below equals scatter.
Black Body Radiation 3
1.All marco objects omit this
2.Depends on temp, energy emitted at wave lengths
3.Temp goes up more light is emitted at shorter wave lengths.
Total energy emitted.
Two things that tell how much energy is emitted from an object.
Temp and area.
Absorbs gas at particular wave lengths
Emission Spectrum when we heat gas.
How would a spinning star look? 3
2.Light towards you would be blue shifted.
3.Blurred broading wave.
Thermonuclear Energy Core
Has nuclear fusion going on helium adam changed to hydrogen adams.
Aparent Magnitude 3
1.Size of the star.
2.Classified stars into six brightness classes.
3.Each step 2.5 brightness coming to your eyes.
Apparent properties do not depend distance and intrinsic properties depend on distance.
True or False
Apparent magnitude a star would have at a distance of 33 lyrs.
True or False
O, B, A, F, G, K, M
Temperature scale that measures like stars. Hottest starting with O and getting cooler as you go down. 7 classes.
How to find Luminosity?
L=(alpha)Area x temperature to the fourth
Hertsprung and Russel found that 90% of stars are main sequence.
True or false
Find luminosity from H-R diagram
7 properties of a star
1. surface area
2. distance stellar parallax
3. temperature spectral type
4. luminosity absolute magnitude
5. chemical composition
7. radial veolcity
What star properties 2 are not instrustic and which one is?
Brightness and distance
1. Tell us mass.
2. Pair of stars that orbit each other.
3. gravitionally bound together
Visual binary stars
Same direction but very long distance apart and are not bound
2 nuclei form 1 nucleus and create lots of energy. This needs high temperature, high density, and high speed to happen.
1. 10% of observed mass of galaxy
2. very low dense
3. mostly hydrogen
dark dense regions where stars are formed
beginning of a star's life
Length of time star spends on main sequence.
main sequence lifetime ( high mass stars spend less time.)
Stages a star takes to become giant. 4
1. Helium core shutdown
2. rapid collaspe hydrogen fusion
3. heat from envelope expands and cools
4. core collapses until heluim gets dense enough and hot enough to fuse
less than 2 solar masses that lets fusion reaction runaway and very exotic
Turnoff point tells age of star
True or false
Method of determing a star's distance from Earth by measuring its surface temperature, luminosity, and apparent magnitude.
Planetlike bodies with less than 0.08 solar massthat cannot sustain fusion in their cores.
low mass main sequence star
Stellar evolution is the sequence of changes in the
characteristics of a star resulting from the physical processes occurring
within it. It is the physical “life history” of a star
Why is stellar evolution difficult to study? 2
1. Stars may exist for billions of years (e.g. Sun is about 4.5 x 109 years old).
2. Humans live for less than 102 years. Meaning
that humans can observe less than 1/107
(1 10 millionth) of a star like the Sun’s life.
3 types of spectra
1. Continuous Spectrum - light like the rainbow
2. Absorption Line Spectrum - dark lines on a continuous spectrum
3. Emission Line Spectrum - mostly dark, no continuity
How can spectrum of light tell a star's chemical compostion?
each element produces its own pattern of spectra lines and with a spectrograph you can see the lines.