SIFTIR: Spectro-polarimetric Imaging Fourier Transform Spectrometer for the InfraRed

Colby Jurgenson, University of Denver
Robert Stencel, University of Denver

Description

Observations of evolved stars in the infrared are well suited for studies of dusty environments, providing a wealth of absorption and emission bands with which to diagnose grain characteristics. We are currently developing an instrument that will employ a Fourier transform spectrometer in conjunction with TNTCAM2 (Klebe et al. 1998), an imaging polarimeter. The FTS component will enhance TNTCAM2, giving the instrument a maximum resolution of 2000 at 10 11m. The FTS is capable of operating between 2-15 11m, but polarimetry for the instrument is limited to the 8-15 11m region due to waveplate/wiregrid characteristics. SIFTIR, the Spectro-polarimetric Imaging Fourier Transform spectrometer for the InfraRed, will build upon the results of TNTCAM2 (Jurgenson et al. 2003). Imaging polarimetry has the potential to trace polarization magnitude and P.A. changes throughout an extended region of interest. TNTCAM2, though capable of a fair degree of spatial resolution, lacked spectral resolution needed to carry out the analysis for approximating grain shapes (e.g. Hildebrand & Dragovan 1995). Holloway et al. (2002), established correlations in polarization magnitude and position angle between the 10 11m silicate feature and the 3 11m water ice feature in a small sample ofYSO's. The existence of a correlation makes plausible the argument that silicate grains might provide nucleation sites for grain growth in a core-mantle arrangement. SIFTIR not only has the capability to cover both the near and mid-IR spectral regions to check for polarization correlations, but will also have the resolution necessary to characterize the grain shapes.

 
May 10th, 9:00 AM

SIFTIR: Spectro-polarimetric Imaging Fourier Transform Spectrometer for the InfraRed

Salt Lake Community College

Observations of evolved stars in the infrared are well suited for studies of dusty environments, providing a wealth of absorption and emission bands with which to diagnose grain characteristics. We are currently developing an instrument that will employ a Fourier transform spectrometer in conjunction with TNTCAM2 (Klebe et al. 1998), an imaging polarimeter. The FTS component will enhance TNTCAM2, giving the instrument a maximum resolution of 2000 at 10 11m. The FTS is capable of operating between 2-15 11m, but polarimetry for the instrument is limited to the 8-15 11m region due to waveplate/wiregrid characteristics. SIFTIR, the Spectro-polarimetric Imaging Fourier Transform spectrometer for the InfraRed, will build upon the results of TNTCAM2 (Jurgenson et al. 2003). Imaging polarimetry has the potential to trace polarization magnitude and P.A. changes throughout an extended region of interest. TNTCAM2, though capable of a fair degree of spatial resolution, lacked spectral resolution needed to carry out the analysis for approximating grain shapes (e.g. Hildebrand & Dragovan 1995). Holloway et al. (2002), established correlations in polarization magnitude and position angle between the 10 11m silicate feature and the 3 11m water ice feature in a small sample ofYSO's. The existence of a correlation makes plausible the argument that silicate grains might provide nucleation sites for grain growth in a core-mantle arrangement. SIFTIR not only has the capability to cover both the near and mid-IR spectral regions to check for polarization correlations, but will also have the resolution necessary to characterize the grain shapes.