Name: __________________________________________ Date: ___________ Period: ______
Stars and Stellar Evolution (video - https://tinyurl.com/4aa6nxrs)
1)
What is a star? __________________________________________________________________
2)
How do stars create energy? _________________________________________________________
_________________________________________________________________________________.
3)
Two hydrogen atoms fuse together to form _____________.
4)
A simple explanation of fusion:
Light Element + Light Element → _____________ Element + _______________
5)
All of the _____________________ of the universe actually formed with _______________.
6)
How do stars form? Stars begin as a cloud of dust and gas, called a _____________, which contracts
and heats due to _____________, until it is hot enough for _______________ to begin.
7)
Gravity causes the nebula to contract or collapse and heat up and if it gets hot enough fusion will begin
a star will begin. We call it a __________________, or baby star.
8)
Stars exist in a variety of ____________, temperatures and ________________.
9)
How long do stars live? The star's life cycle depends entirely on ____________.
10) Small stars live ________ lives, have ______________ temperatures and have ___________ deaths.
11) Large stars live ________ lives, have ______________ temperatures and have ___________ deaths.
12) So what about our Sun? Main Sequence (~____BYA) → Swell to a ______ Giant → Shrink to a
White __________ → Cool to a _________ Dwarf.
Stars and the H-R Diagram
The Hertzsprung-Russel/ diagram is a graph that illustrates the relationship between the average surface
temperature of stars and their absolute magnitude, which is how bright they would appear to be if they
were all the same distance away. Rather than speak of the brightness of stars, the term "luminosity" is often
used. Luminosity is a measure of how much energy leaves a star in a certain period of time. Generally, for
stars that are at equal distances from the Earth, the more luminous a star, the brighter it is. The luminosity
of stars is affected not only by temperature but also by size. The most luminous stars would be those that
are large and hot. Those that are the least luminous would be small and cool. The color of a star is
determined by its surface temperature, which is illustrated on the Hertzsprung-RusselI diagram.
1)
What is the approximate surface temperature of the sun? ______________
2)
Is the surface temperature of white dwarf stars higher or lower than red supergiants? ______________
3)
List the color of the stars from hottest to coldest: __________________________________________
4)
Most of the stars on the HR Diagram are classified as which type of star? _______________________
5)
How is it possible for white dwarf stars to have lower luminosity than the sun even though the sun is
cooler than white dwarfs? ___________________________________________________________
6)
Plot the following stars using the temperature and Luminosity. Then Identify the type/color for each.
Star A
Star B
Star C
Star D
Temp
4,000 °C
6,000 °C
20,000 °C
6,000 °C
Lumin
low/medium
high
low/medium
medium
Color
Type
If stars fascinate you, check out this article that takes a deeper look at stars: https://tinyurl.com/2p93csn8