共查询到20条相似文献,搜索用时 156 毫秒
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尤建圻 《紫金山天文台台刊》1981,(2)
本文提出了一种用于太阳观测的光束分裂器的设计,它可以把太阳像或光谱带变成若干个大小相同强度不同的像。这种光束分裂器可以用于多种测量,特别适用于强度差很大的谱线分析工作。用这种原理制成的光束分裂器已成功地应用到1980年2月16日日全食闪光光谱观测中。文中还分析了光路中加用了光束分裂器之后对色散,象畸变等方面的影响。 相似文献
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20个激变变星或相关天体的分光证认 总被引:1,自引:0,他引:1
在20个研究得很少的激变变星或者曾经被分类为激变变星的相关天体的光谱中,13个被证实为属于激变变星(65%),另外7个似乎应该被排除(表1第8列),不像其他研究者那样,仅给出非激变变星或热天体,还以更强的证据和更多的光谱特征征认出1个DA型白矮星,4个双星系统及其子星的光谱型。新的光谱资料不支持FY Per的Herbig Ae/Be分类,它是一个激变变星。对于PG1712+493,不仅给出星和云的 相似文献
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主要介绍了抚仙湖1 m新真空太阳望远镜(the 1-meter New Vacuum Solar Telescope,NVST)6 m水平式近红外光谱仪的安装过程和实测结果。主要讨论内容是光路设计特点、光学系统的装调以及利用该光谱仪对活动区NOAA 11662黑子进行的初步近红外光谱实测(波长1.56μm附近)。成功观测到由黑子强磁场造成的Fe I 1.56μm谱线裂变现象,并初步估算了磁场强度。该光谱的成功装调和使用,充分实现了对9 m光谱仪光学系统的整体检测,为9 m光谱仪的安装调试提供了宝贵的经验和参考。 相似文献
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李如凤 《紫金山天文台台刊》1999,18(2):141-143
云南天文台太阳光谱望远镜是无偏振对称光路系统,经过重新装调望远镜空间分辨率在1”以内,光谱上的空间分辨率在1”~2”,跟踪精度在5 分钟内1”,以上光学参数达到可以加装Stokes 偏振分析器,用于参加23 周太阳峰年矢量磁场的光谱轮廓研究 相似文献
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Laurent Koechlin Jean-Pierre Rivet Paul Deba Denis Serre Truswin Raksasataya René Gili Jules David 《Experimental Astronomy》2012,33(1):129-140
This paper presents high contrast images of sky sources, obtained from the ground with a novel optical concept: Fresnel arrays. We demonstrate the efficiency of a small 20?cm prototype Fresnel array for making images with high brightness ratios, achieving contrasts up to 4 × 105 on sky sources such as Mars and its satellites, and the Sirius?A?CB couple. These validation results are promising for future applications in space, for example the 4 m array we have proposed to ESA in the frame of the ??Call for a Medium-size mission opportunity for a launch in 2022??. Fresnel imagers are the subject of a topical issue of Experimental Astronomy published in 2011, but only preliminary results were presented at the time. Making images of astronomical bodies requires an optical component to focus light. This component is usually a mirror or a lens, the quality of which is critical for sharp and high contrast images. However, reflection on a mirror and refraction through a lens are not the only ways to focus light: an alternative is provided by diffraction through binary masks (opaque foils with multiple precisely etched sub-apertures). Our Fresnel arrays are such diffractive focusers, they offer weight, price and size advantages over traditional optics in space-based astronomical instruments. This novel approach requires only void apertures of special shapes in an opaque material to form sharp images, thus avoiding the wavefront distortion, diffusion and spectral absorption associated with traditional optical media. In our setup, lenses and/or mirrors are involved only downstream (at small sizes) for focal instrumentation and chromatic correction. Fresnel arrays produce high contrast images, the resolution of which reaches the theoretical limit of diffraction. Unlike mirrors, they do not require high precision polishing or positioning, and can be used in a large domain of wavelengths from far IR to far UV, enabling the study of many science cases in astrophysics from exoplanet surfaces and atmospheres to galaxy evolution. 相似文献
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Paul Sommers 《Astroparticle Physics》1995,3(4):349-360
Recent reports of superhigh energy cosmic rays beyond the expected spectral cutoff have intensified interest in the unknown origin of the highest energy cosmic rays. There is a need for a much larger data base of more precisely measured air showers. This requires new sensitive detectors of enormous aperture. Combining a ground array of particle counters with an optical detector of atmospheric fluorescence yields a detector of outstanding capability. Such a hybrid detector provides far more accurate measurements of energies, arrival directions, and primary particle atomic masses than can be achieved by either type of detector separately. 相似文献
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X-ray polarimetry can be an important tool for investigating various physical processes as well as their geometries at the celestial X-ray sources. However, X-ray polarimetry has not progressed much compared to the spectroscopy, timing and imaging mainly due to the extremely photon-hungry nature of X-ray polarimetry leading to severely limited sensitivity of X-ray polarimeters. The great improvement in sensitivity in spectroscopy and imaging was possible due to focusing X-ray optics which is effective only at the soft X-ray energy range. Similar improvement in sensitivity of polarisation measurement at soft X-ray range is expected in near future with the advent of GEM based photoelectric polarimeters. However, at energies >10 keV, even spectroscopic and imaging sensitivities of X-ray detector are limited due to lack of focusing optics. Thus hard X-ray polarimetry so far has been largely unexplored area. On the other hand, typically the polarisation degree is expected to increase at higher energies as the radiation from non-thermal processes is dominant fraction. So polarisation measurement in hard X-ray can yield significant insights into such processes. With the recent availability of hard X-ray optics (e.g. with upcoming NuSTAR, Astro-H missions) which can focus X-rays from 5 KeV to 80 KeV, sensitivity of X-ray detectors in hard X-ray range is expected to improve significantly. In this context we explore feasibility of a focal plane hard X-ray polarimeter based on Compton scattering having a thin plastic scatterer surrounded by cylindrical array scintillator detectors. We have carried out detailed Geant4 simulation to estimate the modulation factor for 100 % polarized beam as well as polarimetric efficiency of this configuration. We have also validated these results with a semi-analytical approach. Here we present the initial results of polarisation sensitivities of such focal plane Compton polarimeter coupled with the reflection efficiency of present era hard X-ray optics. 相似文献
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The Montreal Infrared Camera (MONICA) consists of a LN2 cryostat enclosing a NICMOS3 array, re-imaging optics and a filter wheel mechanism containing broad-band and circular variable filters. A polarimetry mode with a warm half wave plate and a cold polarizer/filter combination is also supported. At the CFHT 0.5 (FWHM) images are routinely obtained with limiting magnitudes of 22.8 at J and 21.7 at K (S/N=3 in 1hr).The Spectrometre Infrarouge de Montréal (SIMON) is a versatile grating spectrometer with spectral resolutions ranging from 300 to 5000. Presently under construction, this spectrometer will initially contain a 512×512 HgCdTe array. Use of reflective optics will allow a future upgrade to a similar format InSb array, extending the wavelength coverage to 5m. SIMON will also have an imaging mode to facilitate the centering of objects within interchangeable slits. 相似文献
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We have used Monte Carlo simulations to investigate the capabilities of a giant air shower observatory designed to detect showers initiated by cosmic rays with energies exceeding 1019 eV. The observatory is to consist of an array of detectors that will characterise the air shower at ground level, and optical detectors to measure the fluorescence light emitted by the shower in the atmosphere. Using these detectors together in a ‘hybrid’ configuration, we find that precise geometrical reconstruction of the shower axis is possible, leading to excellent resolution in energy. The technique is also shown to provide very good reconstruction below 1019 eV, at energies where the ground array is not fully efficient. 相似文献
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The binary systems that have been detected in gamma rays have proven very useful to study high-energy processes, in particular particle acceleration, emission and radiation reprocessing, and the dynamics of the underlying magnetized flows. Binary systems, either detected or potential gamma-ray emitters, can be grouped in different subclasses depending on the nature of the binary components or the origin of the particle acceleration: the interaction of the winds of either a pulsar and a massive star or two massive stars; accretion onto a compact object and jet formation; and interaction of a relativistic outflow with the external medium. We evaluate the potentialities of an instrument like the Cherenkov telescope array (CTA) to study the non-thermal physics of gamma-ray binaries, which requires the observation of high-energy phenomena at different time and spatial scales. We analyze the capability of CTA, under different configurations, to probe the spectral, temporal and spatial behavior of gamma-ray binaries in the context of the known or expected physics of these sources. CTA will be able to probe with high spectral, temporal and spatial resolution the physical processes behind the gamma-ray emission in binaries, significantly increasing as well the number of known sources. This will allow the derivation of information on the particle acceleration and emission sites qualitatively better than what is currently available. 相似文献
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To try to understand the behavior of helium variability in Chemically Peculiar stars, we continued our on‐going observational campaign started by Catanzaro, Leone & Catalano (1999). In this paper we present a new set of time resolved spectroscopic observations of the HeI5876 Å line for a sample of 10 stars in the spectral range B3 ‐ A2 and characterized by different overabundances. This line does not show variability in two stars: HD77350 and HD175156. It shows instead an equivalent width variation in phase with the Hipparcos light curve for two stars: HD79158 and HD196502. Antiphase variations have been found in 4 stars of our sample, namely: HD35502, HD124224, HD129174 and HD142990. Nothing we can say about HD115735 because of the constancy of Hipparcos photometric data, while no phase relation has been observed for HD90044. In the text we discuss the case of HD175156, according to photometric calibration and our spectroscopic observations we rule out the membership of this star to the main sequence chemically peculiar stars. We confirm the results obtained in the previous paper for which phase relations between light, spectral and magnetic variations are not dependent on stellar spectral type or peculiarity subclass. 相似文献
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The one-minute, five-minute, and hourly values of cosmic-ray intensity obtained with a scintillation telescope at Izmiran have been used to carry out the correlational and spectral analysis of large Forbush-decreases of cosmic rays in 1978. The spectra of power obtained for the periods of interplanetary disturbances are characterized by individual spectral lines whose amplitude exceeds at least a 95% interval of reliability. 相似文献
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P. von Ballmoos 《Experimental Astronomy》1995,6(4):85-96
Gamma-ray lines are the fingerprints of nuclear transitions, carrying the memory of high energy processes in the universe. Setting out from what is presently known about line emission in gamma-ray astronomy, requirements for future telescopes are outlined. The inventory of observed line features shows that sources with a wide range of angular and spectral extent have to be handled: the scientific objectives for gamma-ray spectroscopy are spanning from compact objects as broad class annihilators, over longlived galactic radioisotopes with hotspots in the degree-range to the extremely extended galactic disk and bulge emission of the narrow e– e+ line.The instrumental categories which can be identified in the energy range of nuclear astrophysics have their origins in the different concepts of light itself: geometrical optics is the base of modulating aperture systems-these methods will continue to yield adequate performances in the near future. Beyond this, focusing telescopes and Compton telescopes, based on wave- and quantum- optics respectively, may be capable to further push the limits of resolution and sensitivity. 相似文献
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M. T. Karimie 《Astrophysics and Space Science》1985,115(2):251-255
Synthetic light curve solutions for the W UMa-system BV Dra have been determined by applying the Wilson and Devinney approach toUBV-observations of 1979–1980 andBV-observations of 1976. All solutions are very similar and correspond to a system with an overcontact configuration and an A-type light curve. A reasonable solution results from the assumption of a G1V spectral type for the primary component. Solutions with a F7V spectral type for the primary component are also presented. The photometric mass ratios are close to the spectroscopic values. 相似文献