Science

A central part of my research throughout my career has been the role of HII regions and the massive stars that power them. This figure is an 850 micron image (taken with the SCUBA-2 camera) of the cold dust cloud associated with the HII region S305. This was part of a study of dense clouds associated with HII regions that formed a part of the Ph.D. thesis of my former student Gopika Sreenilayam and has recently been accepted for publication in the Astronomical Journal.

This image of the HII region S128 shows an overlay of an 850 micron image (SCUBA-2) in blue, a radio picture in red (VLA image at 6 cm), and an infrared picture in green (Spitzer IRAC image at 8 microns). The small HII region at the top is shown embedded in the cold dust cloud seen in the SCUBA-2 image and is hidden from view in the visible. The large HII region below that is very bright in the visible, not obscured by clouds of interstellar material in the area. The infrared data shows the presence of very hot interstellar material, either dust grains or very large molecules (PAHs), close to the hot ionized gas of the HII region. This work is also a part of Dr. Sreenilayam's Ph.D. thesis and is part of a paper currently in preparation for publication.

This image, the VLA portion of the above composite image of S128, is part of an extensive survey producing very high resolution radio images of HII regions in the Milky Way. These images are being used for numerous other projects into the evolution of massive star forming regions. An early version of this study was published many years ago but the new version significantly improves the resolution of the images.

Spectra of strong water emission lines from the NGC 7129 star-forming region obtained with the HIFI instrument on the Herschel Space Observatory. From our analysis of these lines we were able to show that this supposedly simple, and very young, intermediate-mass star forming region is considerably more complex that was previously thought and that this object shows many characteristics thought to be only common in much higher mass, much more luminous and hot star forming regions. This work has been published recently in the journal Astronomy and Astrophysics Letters.

Other projects include: