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Table
of Contents
Evolution
of Stars
30
Bright Stars
30 Nearest Stars
Questions
Intro
to Astronomy
Misconceptions
Archaeoastronomy
Equitorial Coordinates
Understanding the Seasons
Time & Its Measurement
Telescopes
Solar
& Lunar Eclipses
The
Solar System
The
Earth
The
Moon
Mecury,
Venus, Mars
The
Outer Planets
Solar
System Debris
The
Sun
Intersteller
Matter
Sky
Literacy
|
|
Approximate Characteristics
of Several Types of Main Sequence Stars
|
Class
|
Mass Compared to Sun
|
Contraction to Zero Age Main Sequence
|
Surface Temp (°K)
|
Luminosity compared to Sun
|
Years on Main Sequence
|
Radius in Suns
|
|
O6 (mid)
|
25
|
10 Th
|
35,000
|
80,000
|
3 M
|
8
|
|
O9 (late)
|
15
|
100 Th
|
28,000
|
15,000
|
15 M
|
6
|
|
B2 (early)
|
9
|
400 Th
|
18,000
|
2,200
|
40 M
|
4
|
|
B5 (mid)
|
5
|
1 M
|
13,000
|
325
|
175 M
|
3
|
|
A0 (early)
|
3
|
4 M
|
10, 000
|
50
|
500 M
|
2.5
|
|
A7 (late)
|
2
|
10 M
|
8,000
|
10
|
2 B
|
2
|
|
F2 (early)
|
1.5
|
15 M
|
7,000
|
4
|
3 B
|
1.5
|
|
G2 (early)
|
1
|
20 M
|
6,000
|
1
|
10 B
|
1
|
|
K7 (late)
|
0.5
|
40 M
|
4,000
|
0.08
|
55 B
|
0.6
|
|
M8 (late)
|
0.08
|
100 M
|
2,600
|
0.0003
|
2.5 Tr
|
0.1
|
Temperature - SP Class - Color Index Relationships
for Main Sequence Stars
| Temp (°K) |
50,000
|
25,000
|
10,000
|
7,500
|
6,000
|
4,800
|
3,700
|
| SP Class |
O5
|
B0
|
A0
|
F0
|
G0
|
K0
|
M0
|
| Co Index (UBV) |
|
-0.2
|
0.0
|
|
+0.6
|
|
+1.5
|
- Luminosity is proportional to Mass ^ (7 / 2)
- Time on the main sequence = Mass ^ (2 / 5)
- Radius = 1 / Temp² x Luminosity
- Stefan-Boltzmann Law: Enegry per unit area = s * Temp ^ 4
s = Stefan-Boltzmann constant = 5.67 x 10 ^ -5 erg cm ^ -2 K ^ -4
sec ^ -1
- Wien's law: Dominant wavelength of light being emitted by a star
= 0.29 / Temp
- Planck's constant, h = 6.625 x 10 ^ -27 erg sec. Energy = h * Frequency
- Supernova candidates: Stars with masses greater than eight solar
masses.
- Apparent Magnitude (m): Measurement of a body's brightness as seen
from earth.
- Absolute Magnitude (M): Apparent magnitude of an object as seen
from a standard distance of 10 parsecs (32.6 light years).
- Apparent Bolometrice Magnitude (m bol): Measures the total radiation
received from the body outside the earth's atmosphere.
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