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| | Spiral (and other Disk) Galaxies |
 | | Spiral galaxies, "normal" and barred, with conspicuous bulges (especially near their center) are classified "Sa" or "SBa", those which have prominent bulges and pronounced arms are clssified "Sb" or "SBb", and those which are dominated by the arms are "Sc" or "SBc". |
 | | Some of the galaxies, mostly those who had no closer encounters for a longer period of time, and those who have lost most of their interstellar matter for some reason, do not show any conspicuous pattern within their disks; these are often called "S0" or "lenticular" galaxies. |
 | | All disk galaxies have a very different appearance, depending from what direction they are seen, or under which angle toward the line of sight (to us) their disk is inclined. |
| www.seds.org /messier/spir.html (727 words) |
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