CHARACTERIZING [CII] LINE EMISSION IN MASSIVE STAR FORMING CLUMPS

By characterizing the [C II] and far-infrared emission from nearby Galactic star-forming molecular clumps, it is possible to determine whether extragalactic [C II] emission arises from a large ensemble of such clumps, and whether [C II] is indeed a robust indicator of global star formation. We describe [C II] and far-infrared observations using the FIFI-LS instrument on the SOFIA airborne observatory toward four dense, high-mass, Milky Way clumps. Despite similar far-infrared luminosities, the [C II] to far-infrared luminosity ratio, L[C II]/LF IR, varies by a factor of at least 140 among these four clumps. In particular, for AGAL313.576+0.324, no [C II]line emission is detected despite a FIR luminosity of 24,000 L. AGAL313.576+0.324 lies a factor of more than 100 below the empirical correlation curve between L[C II]/LF IR and S(63µm)/S(158µm) found for galaxies. Which lead us to a possibility of AGAL313.576+0.324 being in an early evolutionary “protostellar” phase with insufficient ultraviolet flux to ionize carbon, or in a deeply embedded “hypercompact’ H II region phase where dust attenuation of UV flux limits the region of ionized carbon to undetectably small volumes. This Project further investigates this notion through 3 new [C II] sources AGAL301.136-0.225, AGAL316.752-0.012, and AGAL317.429 -0.561. My contributions were in investigating the three new sources of interest. I worked extensively on near infrared 3D data reduction and data analysis, interpretations and graphical representation.

Advisor: Dr. James W. Jackson