Quantum Well Infrared Photodetector Focal Plane Arrays for Astronomy
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Engineering topics
Publications and source records attributed to Werner, M..
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The mid-infrared spectra (2.5-5 and 5.7-11.6 mu m) obtained by ISOPHOT reveal the interstellar medium emission from galaxies powered by star formation to be strongly dominated by the aromatic features at 6.2, 7.7, 8.6, and 11.3 mu m. Additional emission appears in between the features, and an underlying continuum is clearly evident at 3-5 mu m. This continuum would contribute about a third of the luminosity in the 3-13 mu m range. The features together carry 5%-30% of the 40-120 mu m. range.FIR) luminosity.
We present mid-infrared maps and preliminary analysis for 61 galaxies observed with the Infrared Space Observatory.
Our goal is to test predictions of models attributing the IEFs to polycyclic aromatic hydrocarbons (PAHs). Interstellar models predict PAHs change from singly ionized to neutral as the UV intensity, Go, decreases.
While the baseline for the Next Generation Space Telescope (NGST) is the 1 to 5 um wavelenght interval, compelling astronomical observations become possible at longer wavelenghts.
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In this paper we discuss the optimization of the detector design, material growth and processing that has culminated in realization of 15 micron cutoff 128 x 128 QWIP focal plane array camera, hand-held and palmize 256 x 256 long-wavelength QWIP cameras and 648 x 480 long-wavelength cameras, holding forth great promise for myriad applications in 6-25 micron wavelength range in science, medicine, defense and industry.
We present an overview of the science capabilities enabled by a mid-infrared camera/spectrometer on board the NGST. Even without full mid-IR optimization, a mid-infrared (5-30 microns) instrument on the NGST will be orders of magnitude more sensitive than any equivalent ground-based instrument/telescope combination. In the extragalactic arena, the mid-IR region is critical for a complete understanding of the or high-redshift universe, dusty star-formation regions at low and high redshifts, and starburst vs. AGN discrimination. In the local universe, great strides forward can be made using mid-IR imaging, spectroscopy, and coronagraphy of dusty and rocky disks of all ages, from protostellar to remnant debris disks. Near-neighbor detection and characterization can also be greatly advanced by mid-infrared observations.
We present the results of imaging spectroscopy of the reflection nebula vdB 133, obtained with the infrared camera and circular varable filter wheel on the Infrared Space Observatory (ISO).
Two of the objectives for the Space Infrared Telescope Facility (SIRTF) will be studying the redshifted starlight from quiescent galaxies and studying infrared luminous starburst galaxies.
The Kuiper Airborne Observatory has been a powerful instrument for the study of nearby galaxies, and SOFIA could probe still further into the local Universe.
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This paper describes the status of NASA's Space Infrared Telescope Facility (SIRTF) program.
This paper describes the results of a search for time variability of stars in the central 1 pc region of the galaxy through K-band imaging and photometry.
The polarization of the 100 micron continuum emission has been measured at 14 positions in the dense, warm molecular cloud associated with the arched filaments, or the 'bridge', of the radio arc near the Galactic center. At all positions the percent polarization is found to be quite large, ranging up to 6.5 percent. The polarization is interpreted in terms of thermal emission by magnetically aligned dust grains. The directions of the polarization vectors then indicate that the magnetic field is (1) parallel to the long dimension of the thermal radio filaments, and (2) very uniform on scales of 1-10 pc. Of several explanations for the inferred field geometry, the simplest is that it results from the unusually large dynamical shear in the emitting cloud.
Forbidden O I 63-micron and forbidden Si II 35-micron fine-structure line emission in M17SW was mapped, and the intensities of the forbidden O I 63 and 146 microns, forbidden Si II 35 microns, and forbidden C II 158 microns were measured at four positions. New 50- and 100-micron continuum maps of the M17SW cloud at comparable resolution to the FIR line observations are presented. Analysis in terms of a homogeneous model yields an incident UV field of 56,000 habings, a density of 30,000 cu cm, and a temperature of about 300 K for the atomic gas. It is concluded that the M17SW photodissociation region is clumpy in nature. The observed forbidden Si II and high-J CO imply the presence of high-density clumps. The clumps dominate the emission in the forbidden O I, Si II, and high-level CO lines, while the forbidden C II, C I, and low-level CO arise mostly in the interclump gas. The extended (about 15 pc) forbidden C II and forbidden C I emission is attributed to the halo gas.
This report documents the propulsion system tasks performed in support of the National Launch System (NLS) Cycle O preliminary design activities. The report includes trades and analyses covering the following subjects: (1) Maximum Tank Stretch Study; (2) No LOX Bleed Performance Analysis; (3) LOX Bleed Trade Study; (4) LO2 Tank Pressure Limits; (5) LOX Tank Pressurization System Using Helium; (6) Space Transportation Main Engine (STME) Heat Exchanger Performance; (7) LH2 Passive Recirculation Performance Analysis; (8) LH2 Bleed/Recirculation Study; (9) LH2 Tank Pressure Limits; and (10) LH2 Pressurization System. For each trade study an executive summary and a detailed trade study are provided. For the convenience of the reader, a separate section containing a compilation of only the executive summaries is also provided.