A tale of two galaxies: light and mass in NGC891 and NGC7814

Understand

The two edge-on galaxies NGC891 and NGC7814 are representative of two extreme morphologies: the former is disk-dominated while the latter is almost entirely bulge-dominated.

• It has been argued (van der Kruit 1983) that since the two galaxies, which are optically so different, have similar rotation curves their total mass distributions cannot be related in any way to the light distributions.
• This would lead to the conclusion that dark matter is the dominating component of the mass.
• We have derived new rotation curves from recent, high-sensitivity HI observations and have found that the shapes of the rotation curves are significantly different for the two galaxies.