Gary Imm

GaryI

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A backyard amateur astrophotographer enjoying retirement with my wife on beautiful Lake Livingston in Onalaska, Texas, about 90 minutes north of Houston.

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Pure Disk Galaxy Bulge A collection by Gary Imm

Pure disk galaxies (PDG) have a flat pancake profile and little if any bulge. Scientists believe that these galaxies have remained isolated and have not encountered another galaxy yet (avoiding a merger and the resulting classical bulge). Scientists are not sure why such a galaxy would not develop a bar and a pseudobulge through its own internal processes, like most other isolated galaxies.

Perhaps the lack of a bulge in PDG galaxies is due to a paucity of gas in their outer disk. Or maybe it is an unknown mechanism which is inhibiting bar formation.

Even though PDGs have no bulge, they are still forming stars. In fact, they seem to have more of a blue appearance than the galaxies in the other categories.

Images in this collection Parent collection:  Galaxy Bulge Features