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[73.07] What Heats Hot Cores? A Study of the Positional Relationships of Hot Core Molecular Emission

S. Watt, L. G. Mundy, F. Wyrowski (University of Maryland)

One of the most intriguing results of studies of high-mass star forming regions has been the discovery of hot molecular cores closely associated with ultra-compact (UC) HII regions (Olmi et al. 1996, Cesaroni et al. 1994). These hot cores are commonly found within 5" of the center of the UC HII region and are found to have masses of 100 - 1000 solar masses and temperatures greater than 100 K (Olmi et al. 1996, Cesaroni et al. 1992, Cesaroni et al. 1994).

We present results of a study of several UC HII regions and their associated hot core emission with the goal of understanding the source of the molecular emission and its relationship to on-going star formation in the region. Recent studies of the Orion and G34.26+0.15 hot cores have suggested that the hot gas emission in these sources may not be due to internal star formation, but rather the result of an interaction between the nearby UC HII and the surface of a dense core.

This poster presents BIMA array maps of the regions, G34.26+0.15, G31.41+0.31, G29.96-0.02, G5.89-0.39, and G9.62+0.19, in C¹⁸O, ¹³CO, CH₃CN, ³⁴SO and the \lambda = 2.7 mm continuum emission. For G34.26+0.15 and G31.41+0.31 we present maps with 0.5" resolution which highlight some major differences and similarities between the sources. G34.26+0.15 appears to be a good example of an externally heated hot core; G31.41+0.31 appears to be a good example of internal heating -- but with a twist.

This material is based upon work supported by the National Science Foundation under Grant No. 96-13716.

Cesaroni, R., Churchwell, E., Hofner, P., Walmsley, C. M. & Kurtz, S. 1994, A&Ap, 288, 903.

Cesaroni, R., Walmsley, C. M., & Churchwell, E. 1992, A&Ap, 256, 618.

Olmi, L., Cesaroni, R., Neri, R. & Walmsley, C. M. 1996, A& Ap, 315, 565.