Optical Surveys and Morphological Studies

The abundance of nearby stellar outflow complexes accessible to observation from the southern hemisphere provides us with the opportunity to study highly supersonic outflows for comparison with theoretical models. Since the publication of the original catalogue of 43 HH objects (Herbig 1972), there has been a substantial increase in the number of known sources due to advances in imaging technology, especially in CCD imagery through narrow-band filters. Catalogues have been compiled by Schwartz (1977; deep red objective-prism survey of southern HH objects), Hartigan and Lada (1985; V, R, I, and H CCD images of suspected HH objects), Strom et al. (1986; broadband V, I, H and [S II] CCD images), Von Hippel et al. (1988; literature survey up to 1988) an Reipurth (1994; extensive notes on individual HH objects with detailed references to the literature). Plans are underway to incorporate [S II], H and broadband images into Reipurth's catalogue (Reipurth 1995).

The ESO/SERC surveys provide matching deep IIIaJ, IIIaF and IVN images of the Southern Sky. Although Reipurth and others have searched the survey material for HH objects, little systematic use has been made of them to identify the driving sources of these flows. HH objects lying close to bright reflection nebula are often swamped by reflected light on IIIaJ and IIIaF plates. Digital Imagery allows sophisticated enhancement techniques to be applied to areas of interest. Use of photographic and more recently digital unsharp masking techniques allows the detection of new emission sources e.g. HH 247 (Malin et al. 1987). It is also possible to overlay IIIaJ, IIIaF and IVN images with infrared and radio maps of sources.

© Copyright Astronomical Society of Australia 1997