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January 10 2010 23:45 UTC | Views: 632 | Comments: 0
Posted by: Kochava in Sky Safari Slideshow
[1] The Sun - our closest star
Amateur Astronomy Picture of the Day for Oct 30, 2009
image credit: Giancarlo Calzetta (Pilolli)
[2] Comparison of mass of hydrogen and helium atoms:
Mass of a hydrogen atom: 1.007825 amu
Mass of 4 hydrogen atoms: 4.0313 amu
Mass of one helium atom: 4.00260 amu
Missing mass: 0.0287 amu
(0.71% of the original mass of the 4 hydrogen atoms)
[3] Comparison of Visual Magnitude and Absolute Magnitude
|
Star
|
Distance
|
Visual magnitude
|
Absolute magnitude
|
Luminosity
Class
|
Spectral
class
|
|
Sun
|
8 light minutes
|
-26.8
|
+4.83
|
V
|
G2
|
|
Sirius
|
8.6 LY
|
-1.44
|
+1.45
|
V
|
A1
|
|
Rigel
|
770 LY
|
+0.18
|
-6.69
|
Ia
|
B8
|
|
Aldebaran
|
65 LY
|
+1.0
|
-0.5
|
III
|
K5
|
|
Vega
|
25.3 LY
|
+0.03
|
+0.58
|
V
|
A0
|
|
Altair
|
16.8 LY
|
+0.76
|
+2.20
|
IV
|
A7
|
|
Deneb
|
3200 LY
|
+1.3
|
-8.7
|
Ia
|
A2
|
[4] Spectral Class Mnemonics:
Oven Baked Apples From Grandma’s Kitchen – Mmmm!
|
“Oh Boy Another F’s Gonna Kill Me.”
“Only Boring Astronomers Find Gratification Knowing Mnemonics!”
“Oh Be A Fine Girl, Kiss Me!”
“Only Boys Accepting Feminism Get Kissed Meaningfully!”
[5] Spectral Classes and examples:
|
Spectral
class
|
Color
|
Surface Temperature
(K)
|
Examples –
main sequence
|
Examples –
giants
|
O
|
Blue
|
30,000 - 50,000
|
Theta-1C Orionis (in Trapezium, in Orion nebula)
|
Alnitak and Mintaka (in Orion’s belt)
|
|
B
|
Blue-white
|
10,000 - 30,000
|
Spica, Regulus, brighter Pleiades (Taygeta, Asterope)
|
Rigel, brighter Pleiades (Alcyone, Electra, Maia)
|
|
A
|
White
|
7500 - 10,000
|
Vega, Sirius, Altair
|
Deneb
|
|
F
|
Yellow-white
|
6000 - 7500
|
Procyon
|
Canopus, Mirfak (Alpha Persei), Polaris
|
|
G
|
Yellow
|
5000 - 6000
|
Sun, Alpha Centauri A
|
Capella
|
|
K
|
Orange
|
3500 – 5000
|
Alsafi (Sigma Draconis), Keid (Omicron-2 Eridani)
|
Arcturus, Aldebaran
|
|
M
|
Red
|
2000 – 3500
|
Barnard’s star, Proxima Centauri
|
Betelgeuse, Antares
|
[6] The Hertzsprung-Russell Diagram
picture credit: www.atlasoftheuniverse.com
[7] Luminosity classes:
Ia, bright supergiant
Ib, supergiant
II, bright giant
III, giant
IV, subgiant
V, main sequence or “dwarf”
[8] Comparison of Spectral Classes
|
Type of Star
|
Spectral
class
|
Surface
Temp (K)
|
Radius
(Sun=1)
|
Mass
(Sun=1)
|
Luminosity
(Sun=1)
|
Lifetime
(millions
of years)
|
Abundance
|
Main Sequence
|
O
|
30,000–50,000
|
10
|
50
|
100,000
|
10
|
0.00001%
|
|
<!--[if !supportEmptyParas]--> <!--[endif]-->
|
B
|
10,000– 30,000
|
5
|
10
|
1000
|
100
|
0.1%
|
|
<!--[if !supportEmptyParas]--> <!--[endif]-->
|
A
|
7500-10,000
|
1.7
|
2.0
|
20
|
1000
|
0.7%
|
|
<!--[if !supportEmptyParas]--> <!--[endif]-->
|
F
|
6000-7500
|
1.3
|
1.5
|
4
|
3000
|
2%
|
|
<!--[if !supportEmptyParas]--> <!--[endif]-->
|
G
|
5000-6000
|
1.0
|
1.0
|
1.0
|
10,000
|
3.5%
|
|
<!--[if !supportEmptyParas]--> <!--[endif]-->
|
K
|
3500-5000
|
0.8
|
0.7
|
0.2
|
50,000
|
8%
|
|
<!--[if !supportEmptyParas]--> <!--[endif]-->
|
M
|
2000-3500
|
0.3
|
0.2
|
0.01
|
200,000
|
80%
|
|
Giant Stars
(low mass stars at the end of their lives)
|
Mostly G, K, or M
|
3000-10,000
|
10-50
|
1-5
|
50-1000
|
1000
|
0.4%
|
|
Supergiant Stars (high mass stars at the end of their lives)
|
Can be O, B, A, F, G, K, or M
|
4000-40,000
|
30-500
|
10-70
|
30,000-1,000,000
|
10
|
0.0001%
|
|
White dwarfs (dying remnant
of a star)
|
D
|
Starts at around 100,000 K, then cools down
|
Under 0.01
|
Under 1.4
|
Under 0.01
|
<!--[if !supportEmptyParas]--> <!--[endif]-->
|
5%
|
[9] The Orion Nebula - A Stellar Nursery
Amateur Astronomy Picture of the Day for Oct 29, 2009
image credit: Ricky Ford
[10] Gaseous Jets from Protostars
image credit: www.hubblesite.org
[11] Minimum Temperature Required to Ignite Fusion Reaction:
Fusion of hydrogen to produce helium: 1 million K
Fusion of helium to produce carbon, oxygen, and neon: 100 million K
Fusion of carbon to produce sodium and magnesium: 600 million K
Fusion of oxygen to produce silicon, phosphorus, and sulfur: 1 billion K
[12] Carbon Star Mu Cephei - "Herschel's Garnet Star"
(wide field view of nebula IC 1396 - Mu Cephei at top left)
picture credit: Slooh
[13] Planetary Nebula M57 - The Ring Nebula
Amateur Astronomy Picture of the Day for Oct 13, 2009
image credit: Tony Farkas
[14] Supernova Remnant M1 - The Crab Nebula
Amateur Astronomy Picture of the Day for Nov 9, 2009
image credit: Richie Jarvis
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