ASTRONOMY CHAPTER 4; Section 3: Stars

What is a star?

In a scientific sense, a star is giant ball of hydrogen and helium with enough mass that it can sustain nuclear fusion at its core.

Stars have 2 types of magnitude (brightness): absolute magnitude and apparent magnitude. How do they differ?

An H-R Diagram is a graph that plots luminosity vs. Temperature for various stars. Create an H-R Diagram Graph of the following stars:
1) Create a graph with the title: Brightness vs. Temperature
2) Label the y-axis (vertical): Increasing Brightness
3) Place increments on the Y-axis from 0 at the vertex to 10 at the top.
4) Label the x-axis (horizontal): Temperature (degrees Kelvin)
5) Place increments on the x-axis in REVERSE OF YOUR NORMAL EXPECTATIONS so that at the vertex(left) you have 30,000 degrees K and at the far right you have 0 degrees K. Make a hash mark every 5,000 degrees.
6) Plot the following stars on your graph:
a. 3000 -----------1
b. 4000 -----------2
c. 5000 ------------3
d. 6000 -----------4
e. 8000 -----------5
f. 10,000 ----------6
g. 12,000 ---------6.5
h. 15,000 ----------7
i. 17,000 ----------8
j. 19,000 ----------9.5
k. 3500 ------------8
l. 4000 -------------8.5
m. 4500 ------------9
n. 6000 -----------10
o. 5500 ------------9
p. 15,000 ---------2
q. 18,000 ----------3
r. 17,000 --------2.5
s. 16,500 ----------2
t. 17,500 ---------1.5

Star “Life Cycles”,8599,2106904,00.html?xid=rss-topstories&utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+time%2Ftopstories+%28TIME%3A+Top+Stories%29&utm_content=Google+International


Click to explore star Cycles

Check Yourself
1) What is a star?
2) What determines whether a protostar becomes a main sequence star or fizzles out into a brown dwarf?
3) What single factor determines which of the 3 different star life cycles a star follows?
4) How much of the current solar system will sun engulf when it becomes a red giant?
5) When will sun become a red giant?
8)What factor determines whether a star "dies" as a black dwarf, neutron star, or black hole?
9)If stars are not alive, why do they have a "life" cycle?
10)What element does a main sequence star fuse together to form Helium?
11)What happens to a star that runs out of hydrogen and then begins fusing Helium into heavier elements?
12)When a super high mass star in its red super giant stage becomes too dense at the core, it becomes more unstable and the core begins to collapse into itself...what explosion sends star dust outward (hint: it is the next stage)?
13)What do we call the line around a black hole that is the "point of no return"? Once matter OR light crosses this line, it is surely pulled into the singularity of the black hole!
14)How old is Sun?
15)How long until Sun runs oout of hydrogen fuel?
16) What is fusion?