Download December 1, 2011 - Perry Local Schools

December 1, 2011
1. Have your H‐R Diagram packet out.
If you are ready to turn in your concept
review, make sure your name is on it and
put it in the tray.
You'll get your HW pass toward the end of class.
This is a simple demonstration activity to prove that the apparent brightness of a star cannot be used to judge its distance.
brightness
1. Place the small flashlight on a desk or table near the front of the room.
2. Place the large flashlight on a desk or table near the back of the room.
3. Gather at the front of the room so they can all see both flashlights easily.
4. Turn on both flashlights.
5. Darken the room.
6. Observe and compare the apparent brightness of the two flashlights.
7. Move the two flashlights back and forth until they both appear to have the same brightness.
A. If you didn’t know which flashlight was which, would you be able to tell which one produced the most light?
B. From this exercise, and the data in table G2a, what conclusion can you draw about the stars Rigel and Sirius?
The thing we notice first about stars is that some are brighter or dimmer. It looks as though the brighter ones are closer to us and the dimmer ones are further away from us. We have just learned that stars vary a lot in the energy, and therefore the amount of light, they produce.
H-R
Dia
gram
Stars come in different sizes and they produce different amounts of energy. The energy a star produces is related to its temperature and color.
White and blue stars: burn their fuel at the highest temperatures produce the most energy
most powerful and most luminous stars
most massive stars Mass is everything to a star. More mass means more self­gravity so the star presses in on itself more strongly.
This means it: gets hotter in the core than a smaller star
it burns faster burns at a much higher temperature gives off more energy than a smaller, cooler star. The Sun fits in the middle of the range of stellar properties. It is a yellow star. Compared to other stars, it is neither very hot nor very cool. It is neither very massive nor very powerful. Because of this we think of the Sun as an average star.
Sometimes the labels are a little different:
The vertical position represents the star's luminosity.
This could be the luminosity in watts.
More commonly it is in units of the Sun's luminosity.
In either case, a ``ratio scale'' is used.
Absolute magnitude is also commonly used. The horizontal position represents the star's surface temperature.
Sometimes this is labelled in by the temperature in Kelvins.
Highest temperatures go to the left. ﴾It's traditional.﴿
Normally the temperature is given using a ``ratio scale.'' Sometimes the stars spectral class ﴾OBAFGKM﴿ is used.
One could also use a measure of color as seen through filters. THE H­R DIAGRAM
1.
What is the approximate surface temperature of the sun? 2. Would the surface temperature of white dwarf stars be higher or lower than red supergiants? (Circle one of the bold words)
3.
What is the color of the stars with the highest surface temperature?
What is the color of the stars with the lowest surface temperature? 4.
List the color of the stars from hottest to coldest: HOT________________________________________________COLD
5.
Most of the stars on the HR Diagram are classified as which type of star? 6. How is it possible for white dwarf stars to have lower luminosity than the sun even though the sun is cooler than white dwarfs?
7. Plot the following stars. Star A = 4,000 0C and low/medium brightness Star B = 6,000 0C and high brightness Star C = 20,000 0C and low/medium brightness Star D = 6,000 0C and medium brightness Identify the type/color for each star:
Star:
Color:
Type:
Star A
Star B
Star C
Star D
8. What is the name of our most popular star located at point D?
Quiz Check - Characteristics of Stars
Galactic Fact Sheet
Answer questions 1-17.
Read through the Galactic Fact Sheet.
3 questions-concerning the features of the image
Galaxies come in an assortment of shapes, sizes, ages and
colors. The galactic hodgepodge seen in the image on the
front from NASA’s Hubble Space Telescope highlights the
diversity of our universe. The image contains thousands of
galaxies. Some of the largest galaxies are members of a small
cluster of galaxies called Abell S0740.
Galaxies Galore Reading-- Highlight
How galaxies are similar and different?
What are colliding galaxies?
Why was Edwin Hubble's work important?
What is the Hubble Space Telescope?