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Spectral Types - 3 Single ionized calcium lines are...

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Spectral Types 1. Type A – Strongest H lines 2. Type B – Slightly weaker H lines 3. Remember, spectrum comes from a stellar atmosphere. 4. Types from hottest to coolest = O B A F G K M 5. Mnemonic for stellar classification – Oh be a fine girl (guy) kiss me. 6. Each type has 10 subgroups Type O 1. Hottest is 30,000 to 60,000 2. So hot all the H is ionized – this makes H spectrum lines weak. 3. H e is ionized to H e II. 4. Stars are short lived, none are close to us. 5. System starts with O 3 Type B 1. Temperature is 30,000 to 10,000˚k. 2. Hydrogen lines are stronger than an O. 3. Neutral H e lines present instead of ionized H e . 4. Rigel and Spice are B stars. Type A 1. Temperature 7,500˚ to 10,000˚k 2. H lines are strongest in this spectrum. 3. Single ionized metals like calcium and magnesium start to appear. 4. Sirius, Deneb, and Vega are class A.
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Class O, B and A are blue to white stars . Type F 1. Temperature is 6,000˚ to 7,500˚k. 2. H lines are weaker than Type A.
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Unformatted text preview: 3. Single ionized calcium lines are strongest. 4. Ca II has a very conspicuous spectrum which is easily recognizable. 5. Ca II spectrum has two lines, all are H K lines. 6. Polaris and Canopus are Type F. Type G 1. Temperature is 5,000˚ to 6,000˚k. 2. Yellowish in color. 3. The peak of the spectra fall in the yellowish/green part of the spectrum. 4. The H, K lines are the strongest in the spectrum. 5. Type G stars have stronger H, K lines than any other type. 6. Sol and Alpha Centauri Type G. Type K 1. Temperature is 3,500˚ to 5,000˚k. 2. The spectra line comes mostly from neutral metals. 3. Has many spectra lines in common with the hottest stars. 4. Arctarus and Aldebaran are type K. Type M 1. Temperature is less than 3500˚k. 2. Looks reddish. 3. Spectrum shows many molecule lines. 4. The Titanium oxide line is very numerous. 5. Betelgeuse (Red Giant) is a Type M....
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