This Presidential Young Investigator Award will support a research program in the physics of regions of star formation and the relationship between star formation and the structure and evolution of galaxies. The next couple of decades hold the potential for great advances in the study of star formation, since the technology and facilities required for definitive observations will first become available during that time. Aspects of star formation of particular interest include: studying the coalescence of diffuse atomic clouds into molecular clouds by determining of the thermodynamic state of galactic and extragalactic diffuse clouds; assessing the impact of massive star formation on the molecular cloud environment by studying the interaction of ionization fronts and outflows from young stellar objects with molecular clouds; searching for true protostars, still in the process of collapse by identifying the spectral signatures of collapse in low-luminosity, low-mass objects in nearby molecular clouds; obtaining strict constraints on the form of the initial mass functions of starbursts, by high resolution observations that determine the intrinsic (de-reddened) luminosity, colors and internal dynamics of the nuclei of starburst galaxies; shedding light on processes which were of importance in past epochs of star formation, and which led to "metal" enrichment of the interstellar medium, by making precise determination of the relative abundance of elements in spiral galaxies. Like many studies of the physics of star formation, these problems are best or exclusively addressed with observations of molecular, atomic or ionic spectral lines at infrared and submillimeter wavelength (1-1000 microns). There remains a great need for better detectors and astronomical instruments at these wavelengths, and the Principal Investigator will continue his work in developing gar infrared detector arrays and spectroscopic instruments which use these devices. He plans to employ detector array technology in constructing a high resolution echelle spectrometer for the 4-14 micron wavelength range. These devices represent substantial extensions of the present capability of infrared spectroscopic instrumentation, and in particular would be of great value in the astronomical projects mentioned above.
