Current Work

Some of the mysteries to be solved here are: What is the source of the outflow? How were the fingers produced? How has the outflow changed the environment of the molecular cloud, thereby affecting future (or current) star formation? Is an outflow of this type actually unusual, or just a brief stage in the life of a high-mass YSO?

Current research on the fingers is focusing on the velocity of the knots. Figure 5 shows the southern two-thirds of the NICMOS field (the entire field is shown in Figure 3b). Selected knots are shown with velocity profiles taken from UKIRT Fabry-Perot data (see Chrysostomou et al 1997). The velocity profiles of a large number of morphologically-interesting structures (e.g. bow shocks of various shapes, knots associated with known HH objects, etc) in the NICMOS image were examined. It was found that only a handful of profile shapes were represented in the field, and that very few of these profiles had red components (Schultz & Burton 2001). This has implications for the orientation of the outflow: if any of the outflow extends back into the molecular cloud, extinction is preventing us from seeing it.

We are also comparing the shapes of the line profiles to shock models which vary parameters such as shock speed, bow shape, and viewing angle. The determination of these parameters for individual knots or fingers will allow us to constrain the velocity and orientation of the outflow. Proper motion studies are also necessary for this, as well as being an important key to determining the source of the fingers.

Other ongoing research deals with the spectra of the fingers. Relative strengths of the lines (both molecular hydrogen and atomic lines) is dependent on parameters such as shock speed and gas density. Along with the space velocity information from the studies mentioned above, these observations provide insights into the expansion of the outflow, including the amount of energy and momentum it deposits into the molecular cloud.

© Copyright Astronomical Society of Australia 1997