Studies of Atomic and Molecular Opacity in Astrophysical Environments and the Application of Computer Modeling of Brown Dwarfs and Extra Solar Planets
This research contributes to the creation of detailed models of extra solar planets. The field of brown dwarfs and extra solar giant planets is continuing to produce new and exciting research results. The number of known extra solar giant planets continues to grow with time and new discoveries. Currently there are almost three hundred extra solar planets known and more are being discovered as new observing techniques are devised. The Spitzer Infrared Telescope (SIRTF) and large, ground based and airborne instruments such as SOFIA are currently being used, or will be, to discover and study new objects along with space observatories such as COROT and the upcoming Kepler mission. In order to make progress in understanding these objects it is necessary to construct detailed models so that their physical properties can be better understood.
Dr. Freedman determines the atomic and molecular opacities for these extra solar objects, which allows calculations of the properties of their atmospheres in order to interpret the observations, and makes it possible to plan strategies for future work.
Using both laboratory data and theoretical calculations, Dr. Freedman maintains large molecular databases for use in the opacity calculations that are essential for the modeling of the atmospheres of these objects. The results of these calculations are then used as input to various programs that compute line by line opacities for use in the models.
These opacity databases have been greatly extended as compared to the usual room temperature laboratory measurements. This is necessary as the room temperature databases have totally inadequate coverage for higher temperatures when excited levels far above the ground state become populated. My own work has used both laboratory and theoretical predictions to extend these databases. My past experience in both laboratory and theoretical work allows me to apply the appropriate techniques to generate and prepare the data for use in my opacity programs. Currently, I am expecting new data to be available for species such as NH3, H2O, and CH4 in the near future. These updates fill important gaps in our knowledge of these spectra.