CLASS COPY – Please do NOT write on this paper. Return this sheet at the end of the class period.
READING: Digging Deeper Earth’s Stellar Neighbors
[Earth Comm Book Pages E 73- E 77]
Directions: Read the tasks presented below for each section of the article. This will give you a reason for your reading. Then
read the corresponding section in your textbook. Record your responses in your science notebook, being sure to include a title,
date, and any other information you need to make a helpful entry. Remember you will be allowed to use your science notebook on
the unit test.
1. According to the inverse square law a star 2X the distance is 1/(2)2 or 1/4 as bright, and a star at
3X the distance is 1/(3)2 or 1/9 as bright.
Calculate the brightness of a star that is at
a. 4X distance
b. 5X distance.
2. Write a statement that describes the relationship between the distance of a star and the
brightness we see.
3. Complete the chart of stellar magnitudes
Object
Magnitude
Visible with
naked eye?
Moon
Sirius A
Object
Magnitude
Visible with
naked eye?
Sun
Dimmest
Hubble star
Dimmest
Ground
telescope star
Dimmest naked
eye stars
4. The Sun is about 6,000 kelvin, what stellar class does it belong to?
5. Rank the following star stages from 1 = smallest to 5 = largest.
_____White dwarf
_____ Neutron Star
_____ Black Hole
_____ Betelgeuse (a red giant)
_____ Sun
6. a. Describe the relationship between mass and the length of a star’s life.
b. Describe the relationship between temperature and the rate at which a star uses its fuel.
7. a. How do you know if a star will end up as a planetary nebula?
b. How do you know if a star will end up as a neutron star or black hole?
8. Use table 1 on page E72 to predict if the star’s life will longer/shorter/ same length as the Sun’s.
Star
Life Span:
longer/shorter/same
Justification for your answer (how did you decide)
Altair
Sirius B
Deneb
9. Write a paragraph to explain the cycle of stellar birth, death and rebirth. Use and underline the
following key terms in your answer: nebula, supernova, main sequence, nuclear fusion, planetary
nebula, dwarf star, galaxy collision, gravity.
CLASS COPY – Please do NOT write on this paper. Return this sheet at the end of the class period.
Answer Key
1. According to the inverse square law a star 2X the distance is 1/(2)2 or 1/4 as bright, and a star at
3X the distance is 1/(3)2 or 1/9 as bright.
Calculate the brightness of a star that is at
a. 4X distance 1/16 as bright
b. 5X distance. 1/25 as bright
2. Write a statement that describes the relationship between the distance of a star and the
brightness we see. The farther away a star is the dimmer it appears to us.
3. Complete the chart of stellar magnitudes
Object
Magnitude
Visible with
naked eye?
Moon
- 12.6
yes
Sirius A
- 1.4
Dimmest naked 6
eye stars
yes
yes
Object
Magnitude
Sun
- 27
Visible with
naked eye?
yes
Dimmest
Hubble star
Dimmest
Ground
telescope star
30
no
25
no
4. The Sun is about 6,000 kelvin, what stellar class does it belong to? G class
5. Rank the following star stages from 1 = smallest to 5 = largest.
__3___White dwarf ___2__ Neutron Star
___1__ Black Hole
___5__ Betelgeuse (a red giant)
___4__ Sun
6. a. Describe the relationship between mass and the length of a star’s life. The greater the mass the
shorter the life.
b. Describe the relationship between temperature and the rate at which a star uses its fuel. The
hotter the star the faster it uses its fuel.
7. a. How do you know if a star will end up as a planetary nebula? Mass of sun or smaller
b. How do you know if a star will end up as a neutron star or black hole?
10 times mass of sun or larger
8. Use table 1 on page E72 to predict if the star’s life will longer/shorter/ same length as the Sun’s.
Star
Altair
Sirius B
Deneb
Life Span:
longer/shorter/same
Same
Shorter
Shorter
Justification for your answer
Nearly the same mass and temperature
Nearly the same mass but much hotter
Nearly the same temperature but much more massive
CLASS COPY – Please do NOT write on this paper. Return this sheet at the end of the class period.
9.
Write a paragraph to explain the cycle of stellar birth, death and rebirth. Use and underline the
following key terms in your answer: nebula, supernova, main sequence, nuclear fusion, planetary
nebula, galaxy collision, gravity, and fuel.
New stars are born from the death of old stars. Nebulae form from material blasted outward by a
supernova or planetary nebulae so they are clouds of old star material. A nebula is the starting
point for the formation of new stars. A galaxy collision or supernova explosion can push the gas
and dust together. When the gas and dust are pushed closer together the force of gravity causes
the nebula to contract until it begins nuclear fusion and becomes a star. The star will spend most
of its life on the main sequence. Once it has used up all its fuel it will begin to die and shed
material that will create a new nebula and start the cycle all over again.