Richtigstellung     

U. Grubenmann 《International Journal of Earth Sciences》1912,3(8):576-576

Ohne Zusammenfassung  相似文献   

Prominences on the Limb: Diagnostics with UV – EUV Lines and the Soft X-Ray Continuum     

U. Anzer  P. Heinzel  F. Fárnik 《Solar physics》2007,242(1-2):43-52

In this paper we discuss the two mechanisms by which solar prominences on the limb can manifest themselves when observed in coronal UV – EUV lines and in the soft X-ray continuum. These mechanisms are the absorption in the resonance continua of hydrogen and helium on one hand and the reduction of the emissivity in a part of the coronal volume occupied by a prominence on the other one. We briefly describe earlier observations made with SOHO/SUMER, EIT and Yohkoh/SXT. We then discuss how the instruments on the new Japanese satellite Hinode can be used for more detailed studies of prominences. We also propose some combined observations between the Hinode satellite and the SOHO/SUMER instrument.  相似文献   

Coupled effects of impact and orogeny: Is the marine Lockne crater,Sweden, pristine?     

T. Kenkmann  F. Kiebach  M. Rosenau  U. Raschke  A. Pigowske  K. Mittelhaus  D. Eue 《Meteoritics & planetary science》2007,42(11):1995-2012

Abstract— Our current understanding of marine‐impact cratering processes is partly inferred from the geological structure of the Lockne crater. We present results of a mapping campaign and structural data indicating that this crater is not pristine. In the western part of the crater, pre‐impact, impact, and post‐impact rocks are incorporated in Caledonian thrust slices and are subjected to folding and faulting. A nappe outlier in the central crater depression is a relic of the Caledonian nappe cover that reached a thickness of more than 5 km. The overthrusted crater is gently deformed. Strike of strata and trend of fold axes deviate from standard Caledonian directions (northeast‐southwest). Radially oriented crater depressions, which were previously regarded as marine resurge gullies formed when resurging seawater erosively cut through the crater brim, are interpreted to be open synclines in which resurge deposits were better preserved. The presence of the impact structure influenced orogenesis due to morphological and lithological anomalies of the crater: i) a raised crater brim zone acted as an obstacle during nappe propagation, (ii) the occurrence of a central crater depression caused downward sagging of nappes, and (iii) the lack of an appropriate detachment horizon (alum shale) within the crater led to an enhanced mechanical coupling and internal deformation of the nappe and the overthrusted foreland. Preliminary results of 3‐D‐analogue experiments suggest that a circular high‐friction zone representing the crater locally hinders nappe propagation and initiates a circumferentially striking ramp fault that delineates the crater. Crustal shortening is also partitioned into the crater basement and decreases laterally outward. Deformation of the foreland affected the geometry of the detachment and could be associated with the activation of a deeper detachment horizon beneath the crater. Strain gradients both vertically and horizontally result in non‐plane strain deformation in the vicinity of the crater. The strain tensors in the hanging and foot walls may deviate up to 90° from each other and rotated by up to 45° with respect to the standard regional orientation. The observed deflection of strata and fold axes within the Lockne crater area as revealed by field mapping is in agreement with the pattern of strain partitioning shown in the analogue models.  相似文献   

Annealing of far infrared photoconductors with infrared diode lasers     

U. Schießl  M. Tacke  J. Wolf  D. Lemke 《Experimental Astronomy》1991,2(3):139-148

High sensitivity infrared detectors made from extrinsic semiconductors are used for astronomical applications on satellite missions in the earth orbit. High energy radiation reduces the sensitivity and changes the calibration of these photoconductors drastically. This process is reversible through on board annealing. Laser emission of mid infrared diode lasers was used for efficient annealing with low power dissipation.  相似文献   

The ALICE instrument and the measured cosmic ray elemental abundances     

J.A. Esposito  E.R. Christian  V.K. Balasubrahmanyan  L.M. Barbier  J.F. Ormes  R.E. Streitmatter  B. Acharya  B. Luzietti  A. Hesse  U. Heinbach  W. Heinrich  M. Henkel  C. Pfeifer  M. Simon 《Astroparticle Physics》1992,1(1)

A Large Isotopic Composition Experiment (ALICE) is a balloon-borne spectrometer which can determine the elemental and isotopic composition of galactic cosmic rays with energies near 1 GeV/nucleon. ALICE was flown from Prince Albert, Canada in August 1987, and remained at float altitude (120000 feet) for 14.7 hours. In this paper, we describe the experimental methods and analysis which will be used for subsequent isotopic analysis. We obtained very precise charge resolution over the entire designed range: 0.10 and 0.16 charge units at neon and iron, respectively. Results on the galactic cosmic ray abundances and absolute fluxes of the elements from neon through nickel are reported.  相似文献   

X-rays from cusps of compact remnants near galactic centres     

Sergei Nayakshin  Rashid Sunyaev 《Monthly notices of the Royal Astronomical Society》2007,377(4):1647-1651

Compact remnants – stellar mass black holes and neutron stars formed in the inner few parsec of galactic centres are predicted to sink into the central parsec due to dynamical friction on low-mass stars, forming a high concentration cusp. Same physical region may also contain very high-density molecular clouds and accretion discs that are needed to fuel supermassive black hole (SMBH) activity. Here we estimate gas capture rates on to the cusp of stellar remnants, and the resulting X-ray luminosity, as a function of the accretion disc mass. At low disc masses, most compact objects are too dim to be observable, whereas in the high disc case most of them are accreting at their Eddington rates. We find that for low accretion disc masses, compact remnant cusps may be more luminous than the central SMBHs. This 'diffuse' emission may be of importance for local moderately bright active galactic nuclei (AGNs), especially low-luminosity AGNs. We also briefly discuss how this expected emission can be used to put constraints on the black hole cusp near our Galactic Centre.  相似文献   

How Does Large Flaring Activity from the Same Active Region Produce Oppositely Directed Magnetic Clouds?     

Louise K. Harra  Nancy U. Crooker  Cristina H. Mandrini  Lidia van Driel-Gesztelyi  Sergio Dasso  Jingxiu Wang  Heather Elliott  Gemma Attrill  Bernard V. Jackson  Mario M. Bisi 《Solar physics》2007,244(1-2):95-114

We describe the interplanetary coronal mass ejections (ICMEs) that occurred as a result of a series of solar flares and eruptions from 4 to 8 November 2004. Two ICMEs/magnetic clouds occurring from these events had opposite magnetic orientations. This was despite the fact that the major flares related to these events occurred within the same active region that maintained the same magnetic configuration. The solar events include a wide array of activities: flares, trans-equatorial coronal loop disappearance and reformation, trans-equatorial filament eruption, and coronal hole interaction. The first major ICME/magnetic cloud was predominantly related to the active region 10696 eruption. The second major ICME/magnetic cloud was found to be consistent with the magnetic orientation of an erupting trans-equatorial filament or else a rotation of 160° of a flux rope in the active region. We discuss these possibilities and emphasize the importance of understanding the magnetic evolution of the solar source region before we can begin to predict geoeffective events with any accuracy.  相似文献   

Neutral hydrogen absorption at the centre of NGC 2146     

A. Tarchi  A. Greve  A. B. Peck  N. Neininger  K. A. Wills  A. Pedlar  U. Klein 《Monthly notices of the Royal Astronomical Society》2004,351(1):339-346

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Bianchi type-VI0 cosmological model in the general scalar-tensor theory of gravitation     

K. Shanthi  V. U. M. Rao 《Astrophysics and Space Science》1990,172(1):83-88

The exact Bianchi type-VI₀ stiff-fluid cosmological model is obtained in the Nordtvedt-Barker general scalar-tensor theory of gravitation. Some properties of the model are discussed.  相似文献   

Joint Russian-American hydrogeological-geochemical studies of the Karachai-Mishelyak system, South Urals, Russia     

E. G. Drozhko  Y. U. Glagolenko  Y. G. Mokrov  G. A. Postovalova  L. M. Samsonova  A. V. Glagolev  S. A. Ter-Saakian  M. L. Glinsky  N. A. Vasil'kova  A. V. Skokov  H. A. Wollenberg  C.-F. Tsang  W. Frangos  R. D. Solbau  K. A. Stevenson  W. M. Lowder  M. G. Foley 《Environmental Geology》1997,29(3-4):216-227

 In September 1994, a Russian-American team conducted hydrogeological, geochemical, geophysical, and radiometric measurements in the territory of the Mayak Production Association, Russia. The primary purpose of these operations was to examine the frontal area of a radioelement- and nitrate-laden groundwater plume moving from the disposal site, Lake Karachai, toward the Mishelyak River. Activities encompassed (1) isolation of hydrologic intervals in two wells and production of water from these intervals, to compare isolated versus open-well sampling methods and to determine hydraulic transmissivities of the aquifer(s); (2) surface and soil-water sampling, accompanying radiometric measurements and subsequent chemical analyses; and (3) electrical resistivity profiling in areas of expected contrasting resistivity. Preliminary results indicate that (1) ⁶⁰Co, ¹³⁷Cs, and ⁹⁰Sr are present in small concentrations (∼0.1% of permissible levels) in water of the Mishelyak River; (2) analyses of water samples collected by a downhole sampler and of water produced from packed-off intervals agree within limits of laboratory accuracy, attesting to the efficacy of the sampling methods presently used by the Russian workers; (3) considerable differences in contaminant concentrations exist between nearby wells, supporting the concept that the plume from Lake Karachai toward the Mishelyak River is controlled by steeply dipping fractures and shear zones; and (4) strong contrasts occur between the electrical resistivities of soil and bedrock. Further collaborative work is strongly recommended and should include more detailed isolation of intervals in wells by multi-packer installations, to better determine the geochemical and hydrological characteristics of the Karachai-Mishelyak system; deployment of a broader soil water and soil sampling array; a more detailed examination of the distribution and concentration of radionuclides by high-resolution field gamma spectrometry; and a detailing of the area's electrical resistivity setting, using a mobile electromagnetic measurement system. Received: 22 January 1996 · Accepted: 1 April 1996  相似文献