Measuring the Stars and the HR Diagram 19 points
Chapter 25
Please use a separate sheet of paper to do the following assignment.
A) Define the following terms using your book:
1) Fusion_At high temperatures, hydrogen nuclei collide, bond, release energy
and create a new element, Helium.
2) Apparent magnitude_ How bright a star looks in the sky.
3) Absolute magnitude :a star’s actual brightness- the amount of light it gives
off.
4) Luminosity—How bright a star is
5) Spectral Class—The temperature of a star.
6) Astronomical Unit (AU) a unit om measure is space = 93 million miles and is
the distance from earth to sun.
7) Light Year (ly)- the distance light travels in one year= 9.5 trillion km or 5.9
trillion miles.
Part 1: 7 points
Part 2: 12 points
B) Answer the following questions using full sentences using the book and your
notes:
1)
What is the Hertzsprung-Russell diagram? This diagram shows the life cycle
of stars using a graph with spectral class (temperature) along the X axis
and brightness (luminosity) along the Y axis. It shows stars along a main
sequence and some stars off of a main sequence. Size of stars indicates
relative mass on the diagram.
2)
What are the specific properties of stars that are depicted on the HertzsprungRussell diagram? The properties depicted on the the Hertzsprung-Russell
diagram are luminosity, spectral class, relative mass, relative color and
relative size.
3)
On the Hertzsprung-Russell diagram, which way does mass decrease? Along
the main sequence, mass decreases to the lower right part of the diagram.
The smallest stars, white dwarfs, appear on the lower left portion of the
diagram.
4)
On the Hertzsprung-Russell diagram which way does Luminosity increase? On
the H-R diagram, luminosity increase in an upward direction or towards
the top of the graph.
5)
What are the general properties of stars on the Hertzsprung-Russell diagram in
the following locations on the Hertzsprung-Russell diagram?
Use complete senteces!!!!
a. Upper Left: Stars in the upper left portion of the H/R diagram will be
hot and bright.
b. Upper Right Stars in the upper right portion of the H/R diagram will be
cool and bright.
c. Lower Left Stars in the lower left portion of the H/R diagram will be hot
but not so bright.
d. Lower Right Stars in the lower right portion of the H/R diagram will be
cool and not so bright.
6)
Describe the life cycle of a low-mass star from start to finish. A low mass star
like the sun is born from a nebula of gases that contracts due to the
shock wave from a nearby dying star. As the nebula contracts, fusion
begins at the core when temperature reaches 15 mill. Degrees.
Throughout its life, the star fuses hydrogen into helium. When hydrogen
runs out, the core of the star will begin to collapse on itself while throwing
of its outer, atmospheric layers. The appearance of the star in this state is
called a planetary nebula—it looks larger –some call it a red giant. After
the outer layers are completely thrown off, the hot small core of the star is
left. This hot, small, not so bright star is known as a white dwarf.
Extra Credit:
7)
If the speed of light is 3.156 * 108 m/s, how many meters are there in a light
year? How many miles? (1 in. = 2.54 cm) Show all your math from start to
finish including all units!