AAS 205th Meeting, 9-13 January 2005
Session 98 High Mass Star Formation and Deeply Embedded Star Formation
Poster, Wednesday, January 12, 2005, 9:20am-6:30pm, Exhibit Hall

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[98.01] Probing the Physical Conditions of High-Mass Star-forming Cores with Dust Continuum and Molecular Ions

Y. L. Shirley, A. Wootten (NRAO), D. Johnstone (HIA), K. Tatematsu (NAOJ), C. Brogan (IfA)

Our understanding of the earliest stages of high-mass star formation is still inchoate. Theoretically, we are limited by a lack of systematic information on the large-scale properties of the regions. While many detailed studies of individual regions have been made, the field has lacked statistical information based on larger samples analyzed with uniform methods. We present a mapping survey of submillimeter dust continuum (850 and 450 micron), N2H+ (J = 1-0 and 3-2), HCO+ (J = 3-2), and HCS+ (J = 6-5) observed with the JCMT 15-m, the NRO 45-m, and the CSO 10.4-m telescopes. Sources are selected from the Plume sample of high-mass star-forming cores with dense gas emission (CS J = 7-6) and H2O masers. In this poster, we highlight the most important results from the survey. Results are compared to previous surveys of 350 micron dust continuum, CS, and HCN emission. Dust continuum radiative transfer models are updated to include the newly observed submillimeter wavelengths, improving constraints on the density and temperature structure of the cores. N2H+ is observed to have smaller linewidths than optically thin dense gas tracers (C34S) and maps of the emission display chemical differentiation toward a few very luminous sources; N2H+ is a probe of colder, more ``quiescent'' gas and is not a reliable dense gas tracer throughout the envelope of high-mass cores. HCO+ line profiles indicate an excess of blue asymmetric, self-absorbed profiles that correlate well with previously observed HCN blue asymmetries; this may indicate large scale collapse in a few high-mass star-forming cores.

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© 2004. The American Astronomical Society.