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Ah, bulges. Oft, where I want one, I cannot get one. But point a finger at me and you’ll hit my central abdominal bulge. Home of the fourteen pieces of pizza from last night. NGC 3621 doesn’t have my problems. No sir. You see unlike most galaxies, NGC 3621 doesn’t have a central bulge.

Bad Astronomy:

At 22 million light years away, NGC 3621 looks like your usual big spiral galaxy: flat disk, arms sweeping out majestically, central bulge… hey, hold on there a second.  Where’s the central bulge?

Turns out, this galaxy doesn’t really have one. There’s a brightening to the center, sure, but no actual spheroidal region of old stars like in most spirals. That’s weird, and something I hadn’t heard of before! A galaxy that’s all disk.

Spirals can have all manners of central bulges.  Andromeda, for example, has a nice puffy one.  The Milky Way has a compact core but has a rectangular bar going across it. Some have huge bulges, some tiny. But I thought there always  was one. But that’s not the case.

NGC 3621 is the talk of the universe. Other galaxies gawk in jealous rage. I’m just blathering. For more on this, read the full article “A galaxy that’s all hat and no head” by Phil Plait.