Table of Spectral Types

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Spectral   Color         Photosphere         Spectral lines       Examples
 Type                    Temperature
                            (K)
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 O          blue-violet  30,000--50,000      Ionized atoms,       Mintaka (delta
                                               especially helium    Orion) 

 B          blue-white   11,000--30,000      Neutral helium,      Spica (alpha
                                               some hydrogen        Virgo)

 A          white          7500--11,000      Strong hydrogen,     Sirius (alpha
                                               some ionized         Canis Major)
                                               metals 

 F          yellow-white     5900--7500      Hydrogen, ionized    Canopus (alpha
                                               metals (e.g.,        Carina)
                                               calcium, iron)

 G          yellow           5200--5900      Neutral and ionized  Sun, Capella
                                               metals especially    (alpha 
                                               ionized calcium      Auriga)

 K          orange           3900-5200       Neutral metals       Aldebaran
                                                                    (alpha
                                                                    Taurus)

 M          red-orange       2500--3900      Strong titanium      Betelgeuse
                                               oxide, some          (alpha
                                               neutral calcium      Orion)

 L          red              1300--2500      Neutral potassium,   Teide 1
                                               rubidium, cesium,
                                               metal hydrides 

 T          red              below 1300      Strong neutral       Gliese 229B
                                               potassium, some
                                               water (H_2O)
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References:  FK-425;
             CK-286,
               except that it does NOT have the brown dwarf types LT.


Notes:   The OBAFGKM TYPES can be remembered by the mnemonic
           ``O be a fine girl/guy kiss me.''

              (Sometimes the only sensible thing to say.)

         The LT types are brown dwarfs NOT stars.   
           Brown dwarfs have masses in the range 13--75 M_Jupiter.
           The upper limit is 0.08 M_Sun.
           They do NOT burn ordinary hydrogen.
           Briefly they burn deuterium and, if above 60 M_Jupiter, lithium.
           Most of the their electromagnetic radiation emission 
           comes at the expense of the energy of contraction.
           See CK-306 and
               FK-424.

         The OBAFGKMLT types can be remembered by another mnemonic, but
           I can't remember what it is
               (FK-424).
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