High-resolution mid-infrared spectroscopy from SOFIA using EXES

Abstract

The Stratospheric Observatory for Infrared Astronomy (SOFIA) will provide new opportunities for high spectral resolution observations in the mid-infrared. To take advantage of these opportunities, we are developing EXES, the Echelon-Cross-Echelle Spectrograph. EXES will operate from 4.5 microns to 28.5 microns and achieve a velocity resolution of 3 km/s for λ < 10 μm. EXES will be a versatile instrument with three spectroscopic modes: cross-dispersed with R~10⁵; long-slit with R~10⁴; and long-slit with R~3000. The unique aspect of EXES is the high-resolution capability provided by a 1 meter echelon grating and a 256 by 256 low-background Si:As IBC detector. Much of the design and operation of EXES has already been validated by the performance of a very similar ground-based instrument, the Texas Echelon-Cross-Echelle Spectrograph (TEXES). We present here a summary of the EXES design and current status; a brief description of ground-based, high spectral resolution, mid-infrared results; and a look ahead to the possible science using SOFIA and EXES.