Our solar neighbourhood can fit in to this part of the HR diagram. Sirus is the biggest star. There are no giants or supergiants in our neighbourhood. Around 70% is Red Dwarfs.

Star Aberviations:
S=Sun
Ac=Alpha Ceturi A
Si A=Sirus A
Si B=Sirus B
Bs=Barnard's star
PC=Proxima Centuri.

Spectral Types:

O types: They are blue stars, usually supergiants. Very luminous and hot. They are rare stars. They have strong Helium absorbsion lines. Example: Zeta Puppis

B types: They are blue white stars. Mainy giants. They have nutral helium and hydrogen absorbsion lines. Example: Rigel

A types: They are white stars. Range from dwarfs to giants. They have huge hydrogen absorbson lines. Example: Sirius

F types: They are yellow white stars, Mainly dwarfs. They have weak hydrogen and ionised Calcium absorbsion lines. Example: Procyon

G types: They are yellow stars, mainly Dwarfs. They have strong calcium absorbsion lines: Example: the Sun

K types: They are orange stars, can exist as giants & dwarfs. Have metallic absorbsion lines. Example: Arcturus.

M types: The red stars. Existing at extreames either Giants or Red dwarfs. They have strong metallic absorbsion lines. Examples: Betelguese & Proxima Centuari.

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Solar&space is copyrighted to Oliver Tunnah 2005.