共查询到20条相似文献，搜索用时 367 毫秒
1.
2.
E. V. Khutsishvili 《Astronomische Nachrichten》1995,316(5):291-293
Basing on the analysis of observational material obtained with the 53-cm coronagraph in Abastumani, the author concludes that chromospheric spicules in hydrogen and helium lines are one and the same formation. Besides, it should be noted that, as a result of radial velocity measurements, it was found that hydrogen and helium D3 lines are emitted from different areas of the same spicule. 相似文献
3.
The new Lyot-coronagraph with 53 cm objective is described. The coronagraph has a grating spectrograph. The solar disk image on the slit of the spectrograph is 12.6 cm. The dispersion is 1 Å/mm in the second order. The coronagraph is situated at the Kislovodsk Station of Pulkovo Observatory, 2050 m above sea level. 相似文献
4.
日冕物质抛射(Coronal Mass Ejection, CME)的检测是建立CME事件库和实现对CME在行星际传播的预报的重要前提. 通过Visual Geometry Group (VGG) 16卷积神经网络方法对日冕仪图像进行自动分类. 基于大角度光谱日冕仪(Large Angle and Spectrometric Coronagraph Experiment, LASCO) C2的白光日冕仪图像, 根据是否观测到CME对图像进行标记. 将标记分类的数据集用于VGG模型的训练, 该模型在测试集分类的准确率达到92.5%. 根据检测得到的标签结果, 结合时空连续性规则, 消除了误判区域, 有效分类出CME图像序列. 与Coordinated Data Analysis Workshops (CDAW)人工事件库比较, 分类出的CME图像序列能够较完整地包含CME事件, 且对弱CME结构有较高的检测灵敏度. 未来先进天基太阳天文台(Advanced Space-based Solar Observatory, ASO-S)卫星的莱曼阿尔法太阳望远镜将搭载有白光日冕仪(Solar Corona Imager, SCI), 使用此分类方法将该仪器产生的日冕图像按有无CME分类. 含CME标签的图像将推送给中国的各空间天气预报中心, 对CME进行预警. 相似文献
5.
6.
Simultaneous observations obtained with the HAO/SPO coronal emission-line polarimeter and the new SPO emission-line coronagraph are compared. The polarimeter data are measured in the Fexiii (10747 Å) line and the coronagraph observations are recorded in the Fexiv (5303 Å) line. The polarimeter field-of-view is relatively coarse compared with the resolution limit of the coronagraph. Therefore, the observed coronal polarization cannot be related directly to the detailed loop structures that characterize the localized coronal distribution, but it is found that large-scale emission features have corresponding polarization signatures. Since the measured linear polarization vectors describe the projected magnetic field direction, as shown theoretically, it follows that the form of the large-scale coronal distribution describes corresponding magnetic field structures. Measured polarization values are consistent with those predicted theoretically. Interpretation of these data to obtain corresponding magnetic field directions suggests that the value usually accepted for iron abundance in the corona might be too large.The National Center for Atmospheric Research is sponsored by the National Science Foundation.Operated by the Association of Universities for Research in Astronomy, Inc. under contract AST 78-17292 with the National Science Foundation. 相似文献
7.
P. N. Frolov I. I. Akhmetov B. B. Shkurskii I. V. Gvozdovskii A. V. Kiselev O. I. Korablev A. V. Tavrov 《Solar System Research》2013,47(6):477-486
Direct observation of exoplanets will make it possible to clarify many principal questions connected both with extrasolar planets and planetary systems and to measure atmospheric spectra of the planets. Obtaining an exoplanet image not distorted by the light from a star is at the cutting edge of present-day optical technologies owing to the combination of tremendous brightness contrasts and small angular distances between the planet and star. To observe the exo-Earth, it is necessary to weaken the brightness of the parent star image by 9–10 orders of magnitude (in the optical and near-IR ranges). To compensate the influence of the atmosphere, ground-based (e.g., 8–10 m) telescopes intended for observing exoplanets are equipped with adaptive optics systems, the spatial and temporal resolutions of which are not yet sufficient. A meter-class space telescope equipped with a star coronagraph will make it possible to observe the nearest exoplanets. In this paper, an improved tool for star coronagraphy is considered, namely, the achromatic interferometric coronagraph with a variable rotational shear. It is fabricated according to the optical scheme of the common path interferometer for studying extrasolar planets by direct observations. Theoretical and experimental estimations for the main characteristics of the scheme were carried out. Laboratory experimental measurements were carried out on a coronagraph model. 相似文献
8.
G��raldine Guerri Jean-Baptiste Daban Sylvie Robbe-Dubois Richard Douet Lyu Abe Jacques Baudrand Marcel Carbillet Anthony Boccaletti Philippe Bendjoya Carole Gouvret Farrokh Vakili 《Experimental Astronomy》2011,30(1):59-81
SPHERE (which stands for Spectro-Polarimetric High-contrast Exoplanet REsearch) is a second-generation Very Large Telescope (VLT) instrument dedicated to high-contrast direct imaging of exoplanets whose first-light is scheduled for 2011. Within this complex instrument one of the central components is the apodized Lyot coronagraph (ALC). The principal aim of this paper is to report the first laboratory experiment of the ALC designed for the SPHERE instrument. The performance and sensitivity of the optical configuration was first numerically studied with an end-to-end approach (see the results in paper I subtitled ??Detailed numerical study??). Made confident by the results, we then tested a prototype on an infrared coronagraphic bench. We measured the transmission profiles of the apodizer prototype and the coronagraphic performance of the apodized Lyot coronagraph in Y, J, and H bands. The coronagraph sensitivity to lateral and longitudinal misalignments of its three main components (apodizer, coronagraphic mask and Lyot stop) was finally studied in H band. We can conclude that the prototype meets the SPHERE technical requirements for coronagraphy. 相似文献
9.
M. Assafin R.P. Campos D.N. da Silva Neto A.H. Andrei 《Planetary and Space Science》2008,56(14):1882-1887
Ground-based observations of faint satellites nearby their planets with 1-2 m class telescopes usually do not allow for high quality astrometry and photometry, due to saturation by the primary or to poor S/N ratio on the satellite images, generally embedded on the scattered light of the planet. Earth-based observations of the Uranus satellites’ upcoming mutual events in 2007-2008 are no exception. In most cases, the event will take place at 4 arcs or less from the planet, with “planet minus satellite” brightness differences of 10 magnitudes. So as to make feasible the observations of these important phenomena, we have developed a prototype of a coronagraph of simple design making use of good quality commercial optical systems. Pilot tests made with this coronagraph with a telescope of show that it is possible to obtain S/N ratios of 50 or higher for 10 s exposures, for satellites as close as 2 Uranus radii from the planet center. We have also developed numerical algorithms which perform digital coronagraphy in the images, with the elimination of the influence of the planets’ scattered light. This procedure considerably improves the S/N ratio of the satellite images (with or without a coronagraph instrument) and shall be applied in the reduction of the observations of the Uranus events so as to achieve the highest possible photometric and astrometric quality. 相似文献
10.
A spectrum scanning Stokes polarimeter 总被引：1，自引：0，他引：1
11.
Singh Dayal Sasikumar Raja K. Subramanian Prasad Ramesh R. Monstein Christian 《Solar physics》2019,294(8):1-19
Solar Physics - In early September 2017, a series of solar flares and coronal mass ejections (CMEs) erupted from the Sun. The Cor2a coronagraph, a unit of the Sun Earth Connection Coronal and... 相似文献
12.
Christ Ftaclas Andreas L. Nonnenmacher Richard J. Terrile Steven H. Pravdo George D. Gatewood Eugene H. Levy 《Astrophysics and Space Science》1994,212(1-2):441-452
The Astrometric Imaging Telescope (AIT) is designed to probe the circumstellar environment by both direct imaging and indirect astrometric measurements. The Circumstellar Imager (CI) is a coronagraphic camera and is the direct imaging component of the AIT. The CI is designed to obtain high-sensitivity images of the circumstellar region. It provides crucial non-inferential information relating to the frequency, origin, and evolution of planetary systems and all forms of circumstellar matter. Such imaging is usually limited by the scattered and diffracted light halos of the star itself, which are greatly suppressed in the CI by mating a novel high-efficiency coronagraph with a phasecompensated optical system. For faint point sources in the circumstellar region, the CI will have a sensitivity in excess of 5 magnitudes fainter than the as-designed Hubble Space Telescope (HST). Laboratory data are shown for the coronagraph, which, in a diffraction-limited environment, is capable of suppressing the stellar diffraction sidelobes by several orders of magnitude without significant sacrifice of field of view. In order to realize the high rejection levels inherent in the coronagraph design, it is necessary to limit scatter in the optical systems, imposing a mid-spatial frequency figure error requirement an order of magnitude smaller than that of the HST. Experimental data directed toward meeting this requirement are also shown.Paper presented at the Conference onPlanetary Systems: Formation, Evolution, and Detection held 7–10 December, 1992 at CalTech, Pasadena, California, U.S.A. 相似文献
13.
The extraction of the kinematic properties of coronal mass ejections (CMEs) from white-light coronagraph images involves a significant degree of user interaction: defining the edge of the event, separating the core from the front or from nearby unrelated structures, etc. To contribute towards a less subjective and more quantitative definition, and therefore better kinematic characterization of such events, we have developed a novel image-processing technique based on the concept of “texture of the event”. The texture is defined by the so-called gray-level co-occurrence matrix, and the technique consists of a supervised segmentation algorithm to isolate a particular region of interest based upon its similarity with a pre-specified model. Once the event is visually defined early in its evolution, it is possible to automatically track the event by applying the segmentation algorithm to the corresponding time series of coronagraph images. In this paper we describe the technique, present some examples, and show how the coronal background, the core of the event, and even the associated shock (if one exists) can be identified for different kind of CMEs detected by the LASCO and SECCHI coronagraphs. 相似文献
14.
We present the current capabilities of a software tool to automatically detect coronal mass ejections (CMEs) based on time
series of coronagraph images: the solar eruptive event detection system (SEEDS). The software developed consists of several
modules: preprocessing, detection, tracking, and event cataloging. The detection algorithm is based on a 2D to 1D projection
method, where CMEs are assumed to be bright regions moving radially outward as observed in a running-difference time series.
The height, velocity, and acceleration of the CME are automatically determined. A threshold-segmentation technique is applied
to the individual detections to automatically extract an approximate shape of the CME leading edge. We have applied this method
to a 12-month period of continuous coronagraph images sequence taken at a 20-minute cadence by the Large Angle and Spectrometric
Coronagraph (LASCO) instrument (using the C2 instrument only) onboard the Solar and Heliospheric Observatory (SOHO) spacecraft. Our automated method, with a high computational efficiency, successfully detected about 75% of the CMEs
listed in the CDAW CME catalog, which was created by using human visual inspection. Furthermore, the tool picked up about
100% more small-size or anomalous transient coronagraph events that were ignored by human visual inspection. The output of
the software is made available online at . The parameters of scientific importance extracted by the software package are the position angle, angular width, velocity,
peak, and average brightness. Other parameters could easily be added if needed. The identification of CMEs is known to be
somewhat subjective. As our system is further developed, we expect to make the process significantly more objective. 相似文献
15.
A. Gherardi M. Romoli E. Pace M. Pancrazzi G. Rossi D. Paganini M. Focardi 《Astrophysics and Space Science》2009,320(1-3):239-241
The HERSCHEL/SCORE is a suborbital mission which will observe the solar corona in UV and in visible light for measurements of solar corona. The coronagraph for such observation is an Italian instrument and, in particular, the CCD camera detectors are developed at the XUVLab of the Department of Astronomy and Space Science of Florence University. Such detectors communicate with the onboard computer by means the IEEE1355 Spacewire standard interface (developed in our laboratories) and implement a lot of smart and custom procedures for imaging. The main innovation of SCORE coronagraph is the first use in space of a variable retarder plate based on liquid crystals and the optical design capable of simultaneous observation in UV and Visible light. 相似文献
16.
G. A. Doschek 《Solar physics》1983,86(1-2):9-17
The solar experiment package on the P78-1 spacecraft is described. The satellite was launched on 24 February 1979 by the U.S. Air Force and contains high resolution Bragg crystal spectrometers, hard X-ray proportional counters, and a white light coronagraph. The high resolution spectrometers were built by the Aerospace Corporation and the Naval Research Laboratory. The hard X-ray spectrometers were built by the Aerospace Corporation and the white light coronagraph was supplied by the Naval Research Laboratory. Most of these instruments are still returning data. 相似文献
17.
目前观测得到的日冕物质抛射(coronal mass ejection,CME)只是其在天空平面的投影,其观测参量与真实参量之间存在一定的差异.而CME的速度是对其地磁效应有决定性影响的参量,因此对CME测量速度作投影效应改正是一个重要的研究课题.综述了近年来对CME测量速度进行投影效应改正的方法,并指出了这些投影效应改正方法中存在的一些问题和进一步的研究方向. 相似文献
18.
M. Youssef 《Earth, Moon, and Planets》2012,109(1-4):13-27
We studied the relation between the near-Earth signatures of the interplanetary coronal mass ejections (ICMEs) shocks such as sudden storms commencement (SSC), and their counterparts of coronal mass ejections (CMEs) observed near-Sun by solar and heliospheric observatory (SOHO)/large angle and spectrometric coronagraph (LASCO) coronagraph during 1996?C2008. Our result showed that there is a good correlation between the travel time of the ICMEs shocks and their associated radial speeds. Also we have separated the ICME shocks into two groups according to their effective acceleration and deceleration. The results showed that the faster ICME shocks (with negative accelerations which decelerated by solar wind plasma) are more correlated to their associated travel time than those with positive accelerations. 相似文献
19.
We have used data from the HAO white light coronagraph and AS&E X-ray telescope on Skylab to investigate the coronal manifestations of 18 prompt solar proton events observed with the GSFC detectors on the IMP-7 spacecraft during the Skylab period. We find evidence that a mass ejection event is a necessary condition for the occurrence of a prompt proton event. Mass ejection events can be observed directly in the white light coronagraph when they occur near the limb and inferred from the presence of a long decay X-ray event when they occur on the disk. We suggest that: (1) the occurrence of mass ejection events facilitates the escape of protons - whether accelerated at low or high altitudes - to the interplanetary medium; and (2) there may exist a proton acceleration region above or around the outward moving ejecta far above the flare site.Also: Dept. of Physics and Astronomy, University of Maryland, College Park, Md. 20742, U.S.A. 相似文献
20.
Phillips K.J.H. Read P.D. Gallagher P.T. Keenan F.P. Rudawy P. Rompolt B. Berlicki A. Buczylko A. Diego F. Barnsley R. Smartt R.N. Pasachoff J.M. Babcock B.A. 《Solar physics》2000,193(1-2):259-271
The Solar Eclipse Coronal Imaging System (SECIS) is an instrument designed to search for short-period modulations in the solar corona seen either during a total eclipse or with a coronagraph. The CCD cameras used in SECIS have the capability of imaging the corona at a rate of up to 70 frames a second, with the intensities in each pixel digitised in 12-bit levels. The data are captured and stored on a modified PC. With suitable optics it is thus possible to search for fast changes or short-period wave motions in the corona that will have important implications for the coronal heating mechanism. The equipment has been successfully tested using the Evans Solar Facility coronagraph at National Solar Observatory/Sacramento Peak and during the 11 August 1999 eclipse at a site in north-eastern Bulgaria. The instrument is described and preliminary results are outlined. 相似文献