Physics professor Luke Keller has been awarded a $25,000 NASA contract to use data from the Spitzer Space Telescope in an ongoing study of solar system formation around distant stars.
Over the next two years, Professor Keller and his students will use spectra from the infrared space telescope to study the light emitted from dust and complex organic molecules that orbit very young stars. They will use the emissions to determine how this dust and gas changes with time and also how the properties of the star affect the orbiting material.
The new study will test whether slight changes in light emission from molecules can allow astronomers to trace the evolution of planet-forming material.
Technical Abstract
Over half of the intermediate-mass young stellar objects in the galaxy (e.g. Herbig AeBe stars or HAeBe) have high-contrast emission in the mid-infrared spectral features of polycyclic aromatic hydrocarbons (PAHs) above the continuum produced by thermal emission from dust in the circumstellar disks. We have examined the PAH emission in detail for a sample of 19 HAeBe stars observed with the Spitzer IRS as part of the IRS Disks GTO program.
Even with this relatively small sample, we have identified some trends that, should they survive in a larger sample of HAeBe stars, will allow us to infer large-scale disk geometry (both inner and outer) and the degree of photo-processing of organic molecular material in HAeBe disks.
The bottom line of our work thus far is that HAeBe apparently have distinctive PAH spectra among the many other astronomical environments that are characterized by strong PAH emission. We therefore propose to apply our spectral analysis methods to an additional 57 HAeBe observed with the IRS and currently (or soon to be) available in the Spitzer archive.
Our total sample of 76 HAeBe stars will allow closer scrutiny of the trends that we have identified in our empirical study and will also be the subject of a detailed disk modeling effort that will include the PAH emission.
