Download Hertzsprung-Russell (H-R) Diagram Hertzsprung-Russell Diagram March 16 −

Hertzsprung-Russell (H-R) Diagram
Hertzsprung-Russell Diagram−March 16
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•
•
• More like test questions
• Do you understand…?
• Fewer leading questions
•
Do you understand? Reading HertzsprungRussell Diagram
Main sequence is a mass sequence
Lifetime of stars
Do you understand? HR Diagram of star
cluster
1.
Stars: A-Aldebaran; B-Barnard’s Star; CCapella; D-Rigel
What do you need to know about stars to
answer the next 4 questions? Pick one 104
correct ans.
a.
b.
c.
d.
e.
• Public viewing sessions at
MSU campus observatory.
2.
3.
4.
5.
• Fri & Sat, 9-11pm, if it is
not cloudy.
• Mar 18 & 19
• Apr 15 & 16
• May 13 & 14
• 24-inch telescope in dome
• small telescopes outside
Hot-plate model of star
Model of the solar interior
How to read H-R Diagram
Spectrum of black body
Energy generation in the sun
Which is the hottest star?
Which is the smallest star?
Which is the biggest star?
If stars A-D replaced the sun, would
people be able to live in Michigan?
a.
b.
c.
d.
e.
Luminosity (Lsun) è
•
• Try new format for some
clicker questions
1
10-4
YNNN
NYNN
NNYN
NNNY
NNNN
O
B
A
F
G
Spectral class
25,000 10,000
6000
ç Temperature (K)
K
M
3000
[see Fig. 11.10]
Hertzsprung-Russell (H-R) Diagram
a.
b.
c.
d.
e.
2.
3.
4.
5.
Hot-plate model of star: L=R2T4
Model of the solar interior X
How to read H-R Diagram
Spectrum of black body: Hotter=>bluer
Energy generation in the sun X
Which is the hottest star?
Which is the smallest star?
Which is the biggest star?
If stars A-D replaced the sun, would
people be able to live in Michigan?
a.
b.
c.
d.
e.
YNNN
NYNN
NNYN
NNNY
NNNN
• Blackbody curve
1
Emitted energy
per unit surface area è
1.
Two Ways:
• Compare amount
of light in two
colors
Stars: A-Aldebaran; B-Barnard’s Star;
C-Capella; D-Rigel
What do you need to know about stars
to answer the next 4 questions? Pick
104
one correct ans.
Luminosity (Lsun) è
•
Taking a star’s temperature
[Fig. 5.10]
5000o
4000o
3000o
Wavelength è
ç Energy
• Spectroscopy
Sodium
10-4
Hydrogen
O
B
A
F
G
Spectral class
25,000 10,000
6000
ç Temperature (K)
K
M
Calcium
Mercury
3000
Neon
Wavelength è
[see Fig. 11.10]
1
Annie Jump Cannon: Classify stars by their spectra
G
AJC
K
• Prof. Pickering’s
Team in 1913, from
Barbara L. Welther,
1982, Isis 73, 94.
• AJC
Flux à
O
B
A
F
• BA, Wellesley, 1884
• Pickering’s assistant,
1896
• Henry Draper
catalog of stars,
1918-1924
• Astronomer 1938
M
G
Wavelength à
Very efficient: Draper catalog has 250,000 stars
AJC 1863-1941
The
TheH-R
H-RDiagram
Diagramwith
withSizes
sizes
Stellar spectral types
Type
106
Temperature
>30,000
B
10,000-30,000
A
7500-10,000
104
F
6000-7500
→
O
G
5000-6000
K
3500-5000
M
<3500
Luminosity
• A Temperature Sequence
102
100
in K
10-2
Extra-Credit for best OBAFGKM mnemonic.
• 3 clicker points for entering.
• 3 clicker points for 10 best answers that can be repeated in class.
• Enter in Angel before
TestTable
3.
[see
11.1]
10-4
25,000
10,000
5,000
Temperature
3,000
2
The H-R Diagram with schematic sizes
Mass determines location on main sequence
106
106
High mass
→
104
102
Luminosity
Luminosity
→
104
100
10-2
[Fig. 11.10]
10-4
102
100
10-2
Low mass
10-4
25,000
10,000
5,000
Temperature
3,000
25,000
10,000
5,000
Temperature
3,000
3