OHANA - Case Study
Markarian 231 is an interesting example
Luminosity = 3x 1012L?, MK = 9.02
Unresolved at 0.1” in IR (50 pc) by PUEO
But down to 1 pc at radio (VLBA)
Compact starburst is thought to be close by (PUEO image, 3D spectroscopy)
Merger (tidal tails) - but single nucleus