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The NGC 1275 enigma
Author(s) -
van Den Bergh Sidney
Publication year - 1977
Publication title -
astronomische nachrichten
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.394
H-Index - 63
eISSN - 1521-3994
pISSN - 0004-6337
DOI - 10.1002/asna.19772980602
Subject(s) - physics , astrophysics , elliptical galaxy , luminosity , spiral galaxy , astronomy , galaxy , irregular galaxy , hubble sequence , interacting galaxy , stars , lenticular galaxy
The following arguments suggest that NGC 1275 does not consist of a giant elliptical (E) galaxy that is colliding with (or is superimposed on) a late‐type spiral (L): 1 The total diameter of the region containing young associations is 33 (100/ H ) kpc. This size is characteristic of ScI galaxies. Neither the morphology nor the integrated luminosity of the L component of NGC 1275 supports such a classification. 2 The chaotic appearance of the L component of NGC 1275 is unlikely to be due to tidal damage. This is so because: (a) the E and L components are still approaching each other, (b) their relative velocity is ≈ 3000 km s −1 , (c) no stripped galaxy core (which would survive a catastrophic tidal encounter) is seen near NGC 1275. 3 The core of the Perseus cluster contains only one (anemic) spiral. The a priori probability that NGC 1275 represents a chance superimposition (or collision) of a spiral and an elliptical galaxy is therefore low. 4 The assumption that the L component of NGC 1275 is superimposed on, but not interacting with, the E component does not account for (a) the presence of an active S EYFERT nucleus, (b) the peculiar filamentary HII shell, discovered by L YNDS , (c) the presence of recently‐formed stars, (d) the X‐ray emission and the radio emission of NGC1275.