Named after Carl K. Seyfert who first described galaxies of this type in 1943. They are galaxies with emission lines from gas in their centre which is not asscociated with stars. The nuclei are called Active Galactic Nuclei due to ths emission, or AGN for short.

These galaxies have been subdivided into two classes, type I and type II. Type I have broad emisison lines while both have narrow emisison lines. The broad line indicate higher density clouds with a lot of thermal broadening.

A unified model has been developed which states that all of these objects are formed by accretion in the centre of the galxy onto supermassive black holes. The spectrum we see is a function of our angle of observation of the object.


Seyferts original list: 

 Galaxy NGC/IC    Type  Con  RA      Dec.    Hubble Type m_v   Dim      Dist

  M 77  NGC 1068  Sy 2    Cet  02:42.7 -00:01  Sb           8.9  8.2x7.3   60
 Per A  NGC 1275  Sy 2    Per  03:19.8 +41:31  Pec         11.9  3.2x2.3  230
        NGC 2782   --     Lyn  09:14.1 +40:07  SAB(rs)a p  11.6  3.8x2.9  
        NGC 3077   --     UMa  10:03.3 +68:44  I0 pec       9.8  5.5x4.1   12
        NGC 3227  Sy 1.5  Leo  10:23.5 +19:52  SAB(s)a p   10.3  6.9x5.4  
        NGC 3516  Sy 1.5  UMa  11:06.8 +72:34  (R)SB(s)0:  11.7  2.1x1.8
        NGC 4051  Sy 1.5  UMa  12:03.2 +44:32  SAB(rs)bc   10.2  5.5x4.6
        NGC 4151  Sy 1.5  CVn  12:10.5 +39:24  SAB(rs)ab:  10.8  6.4x5.5
 M 106  NGC 4258  Sy 1.9  CVn  12:19.0 +47:18  Sbp          8.9 20.0x8.4   25
        NGC 5548  Sy 1.5  Boo  14:18.0 +25:08  SA(s)0/a    12.6  1.6x1.4  
        NGC 6814  Sy 1.5  Aql  19:42.7 -10:19  SAB(s)bc    11.2  3.0x3.0
        NGC 7469  Sy 1.2  Peg  23:03.3 +08:52  SAB(rs)a    12.3  1.5x1.0   

Some more bright Seyfert galaxies: 

        NGC  566  Sy 1    Psc  01:29.0 +32:21  S0          13.5  1.5x0.4
        NGC  985  Sy 1    Cet  02:34.6 -08:47  Pec         13.5  1.3
        NGC 1566  Sy 1    Dor  04:20.0 -54:56  S(s)bc?      9.4  7.1x4.8
        NGC 7742          Peg  23:44.3 +10:46  S           11.5  2.0x2.0

 Mrk 335          Sy 1    Peg  00:06.3 +20:12  S0/a        13.8  0.3x0.3
 Mrk 1155         Sy 2         01:26.2 +33:24  S0          15.0  0.5x0.3
 Mrk 3            Sy 2         06:15.6 +71:02  S0:         14.0  1.8x1.6
 Mrk 509          Sy 1.2       20:44.2 -10:43  Compact     13.0  0.5

Key: 

Galaxy, NGC/IC 
      Identification of the galaxy with other identification and NGC/IC number 
Type 
      Seyfert type (1, 2); "--" indicates that these are no more classified as Seyfert galaxies 
RA, Dec 
      Right Ascension and Declination (J 2000.0) 
Hubble Type 
      Hubble Type 
m_v 
      Apparent visual brightness in magnitudes 
Dim 
      Apparent dimension in arc minutes 
Dist 
      Distance in million light-years 
from -- http://www.seds.org/~spider/spider/ScholarX/seyferts.html
Grzcyrgba says: you might add that Seyferts are spiral galaxies only. The broad line is due to revolution around the black hole. In narrow-line galaxies, the broad line region is probably obscured by dust.

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