HIghMass - High HI Mass, HI-Rich Galaxies at $z\sim0$: Combined HI and
  H$_2$ Observations
  We present resolved HI and CO observations of three galaxies from the
HIghMass sample, a sample of HI-massive ($M_{HI} > 10^{10} M_\odot$), gas-rich
($M_{HI}$ in top $5\%$ for their $M_*$) galaxies identified in the ALFALFA
survey. Despite their high gas fractions, these are not low surface brightness
galaxies, and have typical specific star formation rates (SFR$/M_*$) for their
stellar masses. The three galaxies have normal star formation rates for their
HI masses, but unusually short star formation efficiency scale lengths,
indicating that the star formation bottleneck in these galaxies is in the
conversion of HI to H$_2$, not in converting H$_2$ to stars. In addition, their
dark matter spin parameters ($\lambda$) are above average, but not
exceptionally high, suggesting that their star formation has been suppressed
over cosmic time but are now becoming active, in agreement with prior H$\alpha$
observations.
