astronomy 1020 stellar astronomy spring_2015 day-18
TRANSCRIPT
Astronomy 1020Spring_2015
Day-18Stellar Astronomy
Course Announcements
•Exam-2 – Fri. 3/6 Chapters 5 & (some of) 6• I will collect the L-T books at this time.•Smartworks Chapters 5: Due Wed. 3/4•Smartworks Chapters 6: Due Mon. 3/16•APSU Research and Creativity Forum April 11-12, 2014
• Abstracts are due: 4:30pm Fri., March 21
•Mar. 2 – Last day to drop with an automatic “W”•Apr. 2 – Last day to drop a class.
Luminosity is the total energy (light) emitted by an object in each second.Stefan-Boltzmann lawLuminosity depends on an surface
area (A), and its temperature (T4); Surface Area ∝ R2
Luminosity = 4π R2 T4
Big and Hot objects have greater luminosity than small cool objects
Lecture Tutorial Luminosity: (pg 55)
Work with a partner!Read the instructions and questions carefully.Discuss the concepts and your answers with
one another. Take time to understand it now!!!!
Come to a consensus answer you both agree on.
If you get stuck or are not sure of your answer, ask another group.
20,000 10,000 5,000
Lum
inos
ity (
sola
r un
its)
Temperature (K)
4
2
1
3
5
10,000
100
10
1
0.1
0.01
0.001
0.0001
1,000
Hertzsprung-Russell Diagram
Which star is Hot and Dim?
Temperature (K)
20,000 10,000 5,000
Lum
inos
ity (
sola
r un
its)
Temperature
(K)
4
2
1
3
5
10,000
100
10
1
0.1
0.01
0.001
0.0001
1,000
Which star is Cool and Dim?
Temperature (K)
20,000 10,000 5,000
Lum
inos
ity (
sola
r un
its)
Temperature (K)
4
2
1
3
5
10,000
100
10
1
0.1
0.01
0.001
0.0001
1,000
Which star is Largest?
20,000 10,000 5,000
Lum
inos
ity (
sola
r un
its)
Temperature (K)
4
2
1
3
5
10,000
100
10
1
0.1
0.01
0.001
0.0001
1,000
Which star is smallest?
Temperature (K)
20,000 10,000 5,000
Lum
inos
ity (
sola
r un
its)
Temperature (K)
4
2
1
3
5
10,000
100
10
1
0.1
0.01
0.001
0.0001
1,000
Brightness is the amount of light arriving at a particular place.
Decreases as the distance from a light source increases, obeying an inverse square law.
The light spreads out over a greater area.
24 r
LB
Lecture - Tutorial: Blackbody Radiation (pg. 59)
Work with a partner!Read the instructions and questions
carefully.Discuss the concepts and your answers with
one another. Take time to understand it now!!!!
Come to a consensus answer you both agree on.
If you get stuck or are not sure of your answer, ask another group.
Energy
Output per
second
V I B G Y O
R
Star A
Star B
Wavelength
Star C
V I B G Y O R
Star D
V I B G Y O R
Star A Star A
Which has the longer peak wavelength?
1. Star A
2. Star C
3. SameStar C
Wavelength
V I B G Y O R
Energ
y
Output
per
secon
d
Star A
Which has the lower surface temperature?
1. Star A
2. Star C
3. SameStar C
Wavelength
V I B G Y O R
Energ
y
Output
per
secon
d
Star A
Which star looks red?
1. Star A
2. Star C
3. Both
4. Neither
Star C
Wavelength
V I B G Y O R
Energ
y
Output
per
secon
d
Star A
Which has the greater energy output?
1. Star A
2. Star C
3. SameStar C
Wavelength
V I B G Y O R
Energ
y
Output
per
secon
d
Star A
Which star is larger?
1. Star A
2. Star C
3. SameStar C
Wavelength
V I B G Y O R
Energ
y
Output
per
secon
d
Star A
Which star is larger?
1. Star A
2. Star D
3. Same
Star D
WavelengthV I B G Y O R
Star A
Energy Output per second
Try to determine EVERYTHING about how these four stars compare!! Temp, Energy output, color, size
(area)…..
Object
A WavelengthV I B G Y O R
visible
range
Ene
rgy
Out
put p
er s
econ
d
Object C
WavelengthV I B G Y O R
visible
range
Ene
rgy
Out
put p
er s
econ
d
Object
B WavelengthV I B G Y O R
visible
range
Ene
rgy
Out
put p
er s
econ
d
Object D
WavelengthV I B G Y O R
visible
range
Ene
rgy
Out
put p
er s
econ
d