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The James Webb Space Telescope (JWST) was conceived as the scientific successor to the Hubble Space Telescope (HST) and Spitzer Space Telescope. The instrument suite provides broad wavelength coverage and capabilities aimed at four key science themes: 1) The end of the dark ages: first light and reionization, 2) The assembly of galaxies, 3) The birth of stars and protoplanetary systems, and 4) Planetary systems and the origins of life. To accomplish these ambitious goals, JWST's detectors provide state-of-the-art performance spanning the λ = 0.6–28 μm wavelength range. In this paper, we describe JWST with an emphasis on its infrared detectors. 相似文献
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H. M. Butner G. H. Moriarty-Schieven M. E. Ressler M. W. Werner 《Astrophysics and Space Science》1995,231(1-2):77-80
The exotic quantum process of photon splitting has great potential to explain the softness of emission in soft gamma repeaters (SGRs) if they originate in neutron stars with surface fields above the quantum critical fieldB
cr = 4.413×1013 Gauss. Splitting becomes prolific at such field strengths: its principal effect is to degrade photon energies, initiating a cascade that softens gamma-ray spectra. Uniform field cascade calculations have demonstrated that emission could be softened to the observed SGR energies for fields exceeding about 1014 Gauss. Recently, we have determined splitting attenuation lengths and maximum energies for photon escape in neutron star environments including the effects of magnetospheric dipole field geometry. Such escape energies esc suitably approximate the peak energy of the emergent spectrum, and in this paper we present results for
esc as a function of photon emission angles for polar cap and equatorial emission regions. The escape energy is extremely insensitive to viewing perspective for equatorial emission, arguing in favour of such a site for the origin of SGR activity. 相似文献
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Lisse C. M. Fernández Y. R. A'hearn M. F. Kostiuk T. Livengood T. A. Käufl H. U. Hoffmann W. F. Dayal A. Ressler M. E. Hanner M. S. Fazio G. G. Hora J. L. Peschke S. B. Grün E. Deutsch L. K. 《Earth, Moon, and Planets》1997,78(1-3):251-257
We present infrared imaging and photometry of the bright, giant comet C/1995 O1 (Hale-Bopp). The comet was observed in an
extended infrared and optical observing campaign in 1996–1997. The infrared morphology of the comet was observed to change
from the 6 to 8 jet “porcupine” structure in 1996 to the “pinwheel” structure seen in 1997; this has implications for the
position of the rotational angular momentum vector. Long term light curves taken at 11.3 μm indicate a dust production rate
that varies with heliocentric distance as ∶ r−1.4. Short term light curves taken at perihelion indicate a rotational periodicity of 11.3 hours and a projected dust outflow
speed of ∶ 0.4 km s−1. The spectral energy distribution of the dust on October 31, 1996 is well modeled by a mixture of 70% silicaceous and 30%
carbonaceous non-porous grains, with a small particle dominated size distribution like that seen for comet P/Halley (McDonnell
et al., 1991), an overall dust production rate of 2 × 105 kg s−1, a dust-to-gas ratio of ∶5, and an albedo of 39%.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
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Michael E. Ressler Michael W. Werner Jeff Van Cleve Helen A. Chou 《Experimental Astronomy》1994,3(1-4):277-280
We describe the development of a mid-infrared camera intended for use at the Palomar 5-m telescope and at the NASA Infrared Telescope Facility. The camera is based on Rockwell's HF-16 128×128 Si:As BIB array. This array is unusual in that it has a well depth of approximately 30 million electrons; this will allow the use of traditional broadband astronomical filters (N and Q) while keeping a reasonable field-of-view. Measured array performance indicates that it has a read noise of 1100 electrons and shows non-linearities of <1% up to 65% of full well. In this paper, we discuss the array and its operating characteristics and we give a brief overview of the camera design.National Research Council research associate at JPLSummer Undergraduate Research Fellow at JPL 相似文献
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