Environmental conditions shaping star formation: The Carina Nebula
  Using the Mopra telescope, we have targeted 61 regions in the Carina Nebula,
covering an area of 1.5 square degrees, of bright and compact 870 $\mu$m dust
continuum emission for molecular line emission from a host of 16 spectral lines
at 3mm, including several dense gas tracers. We found that the clumps detected
in Carina in general have in average higher temperatures (27 K compared to 21
K), and lower masses (214 M$_\odot$ compared to 508 M$_\odot$) than clumps
located at a similar distance to us in the Galactic Plane. We compare the
properties of the molecular line emission of these clumps with the MALT90
survey, finding that the detection rates of the molecular lines are similar to
MALT90 clumps that are classified as PDRs. However, most of the clumps located
within 10' of $\eta$ Carina have little molecular line emission detected in our
observations. Given the lack of maser detection in the Carina region, we also
compared the properties the clumps in Carina to those of Galactic clumps
associated with 6.7-GHz methanol masers. We found that the clumps in Carina are
warmer, less massive, and show less emission from the four most commonly
detected molecules, HCO$^+$, N$_2$H$^+$, HCN, and HNC, compared to clumps
associated with masers in the Galactic Plane. Overall our results are
consistent with the scenario in which the high radiation field of $\eta$ Carina
is dramatically affecting its local environment, and therefore the chemical
composition of the dense clumps.
