Young Stellar Objects and Dense Clouds in the W51 Region

We present infrared and millimeter observations of the active star-forming complex W51. A $1.25\;deg\times1.00\;deg$ region that includes the W51 complex was covered in the J = 2 - 1 transition of the $^{12}CO$ and $^{13}CO$ molecules with the University of Arizona Heinrich Hertz Submillimeter Telescope. We use a statistical equilibrium code to estimate physical properties of the molecular gas. Using Spitzer data we identify young stellar objects (YSOs) and fit model spectral energy distributions to these sources and constrain their physical properties. We compare the molecular cloud morphology with the distribution of infrared and radio continuum sources and find associations between molecular clouds and YSOs. We estimate that about 1% of the cloud mass is currently in YSOs.