GBT25B-386

Morphology and Characteristics of the HH 555 Pillar

Abstract

For UMD/GBO agreement.

Molecular pillars form at the boundaries between some of the hottest (10,000K) and coldest (10K) gas in the Galaxy. Many physical processes come into play in the birth and growth of such gaseous pillars: hydrodynamic instability, photo-ionization/dissociation, recombination, molecular heating and cooling, and probably magnetic fields. High-quality observations of the molecular gas to determine the densities, temperatures, pressures, and velocity fields of such systems can validate pillar formation models and give a better understanding of pillar life cycles.

The pillar in the Pelican Nebula associated with HH 555 presents a unique opportunity to study a "simple case": It is a lone pillar, well isolated from surrounding gas and likely formed by the influence of a single O star 9 parsecs away.

We have interferometric observations in CS(2-1), HCO+(1-0), and HCN(1-0) and CO(1-0). These data have high spatial resolution (4-10") and spectral resolution (~0.2 km/s) but require single-dish observations to fill in the missing zero spacings which the GBT the an ideal instrument to provide.

Using ARGUS 16-beam and VEGAS mode 3 we will map a ~3'x5' area in these 4 spectral lines. HCO+/HCN can be done simultaneously. We request 31 hours of total observing time, including overhead.

Investigators

Name	Institution
Marc Pound *	Maryland, University of
Peter Teuben	Maryland, University of

* indicates the PI