منابع مشابه
X-ray Astronomy of Stellar Coronae ⋆
X-ray emission from stars in the cool half of the Hertzsprung-Russell diagram is generally attributed to the presence of a magnetic corona that contains plasma at temperatures exceeding 1 million K. Coronae are ubiquitous among these stars, yet many fundamental mechanisms operating in their magnetic fields still elude an interpretation through a detailed physical description. Stellar X-ray astr...
متن کاملX-ray Interferometry: Ultra High Resolution Astronomy
X-rays have tremendous potential for imaging at the highest angular resolution. The high surface brightness of many xray sources will reveal angular scales heretofore thought unreachable. The short wavelengths make instrumentation compact and baselines short. We discuss how practical x-ray interferometers can be built for astronomy using existing technology. We describe the Maxim Pathfinder and...
متن کاملPhase Fresnel Lens Development for X-ray & Gamma-ray Astronomy
Observations in the hard X-ray and gammaray energy regimes are constrained by limited sensitivity and angular resolution. Significant gains could be made if these high-energy photons could be concentrated from a large area onto a small detector element and if diffraction-limited measurements could be obtained. Furthermore, the angular resolution in the gamma-ray band would be superior to that p...
متن کاملFresnel lenses for X-ray and Gamma-ray Astronomy
Phase Fresnel lenses have the same imaging properties as zone plates, but with the possibility of concentrating all of the incident power into the primary focus, increasing the maximum theoretical efficiency from 11% to close to 100%. For X-rays, and in particular for gamma-rays, large, diffraction-limited phase Fresnel lenses can be made relatively easily. The focal length is very long for exa...
متن کاملComparison of Abdominal X-ray Findings and Results of Surgery in Neonates with Gastrointestinal Obstruction
Background Gastrointestinal (GI) obstruction is one of the most important surgical emergencies in neonates. Surgeons should select between conservative and invasive strategies. Imaging modalities are important in proper diagnosis. This study evaluates the sensitivity of abdominal radiographies (with or without contrast) in detection of neonatal GI obstruction. Materials and Methods A cross-sect...
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ژورنال
عنوان ژورنال: Symposium - International Astronomical Union
سال: 1965
ISSN: 0074-1809
DOI: 10.1017/s007418090017963x