Evidence for interchange reconnection between a coronal hole and an adjacent emerging flux region     

D. Baker  L. van Driel‐Gesztelyi  G.D.R. Attrill 《Astronomische Nachrichten》2007,328(8):773-776

Coronal holes are regions of dominantly monopolar magnetic field on the Sun where the field is considered to be ‘open’ towards interplanetary space. Magnetic bipoles emerging in proximity to a coronal hole boundary naturally interact with this surrounding open magnetic field. In the case of oppositely aligned polarities between the active region and the coronal hole, we expect interchange reconnection to take place, driven by the coronal expansion of the emerging bipole as well as occasional eruptive events. Using SOHO/EIT and SOHO/MDI data, we present observational evidence of such interchange reconnection by studying AR 10869 which emerged close to a coronal hole. We find closed loops forming between the active region and the coronal hole leading to the retreat of the hole. At the same time, on the far side of the active region, we see dimming of the corona which we interpret as a signature of field line ‘opening’ there, as a consequence of a topological displacement of the ‘open’ field lines of the coronal hole. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   

Analysis of burnt schist outcrops in the alps: Relation to historical archaeology and Hannibal's crossing in 218 B.C.     

William C. Mahaney  Michael W. Milner  Rana Sodhi  Ronald I. Dorn  Sal Boccia  Roelf P. Beukens  Pierre Tricart  Stphane Schwartz  Eva Chamorro‐Perrez  Ren W. Barendregt  Volli Kalm  Randy W. Dirszowsky 《Geoarchaeology》2007,22(7):797-816

Identification of the exact route followed by Hannibal during his invasion of Italia in the Second Punic War is one of the major questions of antiquity and one that historians/archaeologists have long studied. One of the many clues in the ancient literature that can help answer this question is the mention of fired rock, the result of a conflagration Hannibal is reputed to have employed to reduce the size of boulders in a blocking rockslide some distance down from the high col on the Italian side. The only route with evidence of fired rock along the roadway leading into Italia follows the Col du Clapier, one of the possible northern routes discussed by historians. Radiocarbon dating of calcined rocks is not possible, but whereas Time‐of‐Flight Secondary Ion Mass Spectrometry (ToF‐SIMS), Field Emission Scanning Electron Microscope (FESEM‐EDS), backscatter electron scanning microscopy (BSE), High Resolution Transmission Electron Microscope (HRTEM), and Raman Spectroscopic data do not provide an age for the burnt rock, compositional evidence of the conflagration derived from these analyses may shed light on Hannibal's actual route. © 2007 Wiley Periodicals, Inc.  相似文献   

Origin and geochemistry of Miocene marine evaporites associated with red beds: Great Kavir Basin,Central Iran     

Hossain Rahimpour‐Bonab  Zeinab Shariatinia  Michael G. Siemann 《Geological Journal》2007,42(1):37-54

During the Cenozoic numerous shallow epicontinental evaporite basins formed due to tectonic movements in the Northern Province of the Central Iran Tectonic Zone (the Great Kavir Basin). During the Miocene, due to sea‐level fluctuations, thick sequences of evaporites and carbonates accumulated in these basins that subsequently were overlain by continental red beds. Development of halite evaporites with substantial thickness in this area implies inflow of seawater along the narrow continental rift axis. The early ocean basin development was initiated in Early Eocene time and continued up to the Middle Miocene in the isolated failed rift arms. Competition between marine and non‐marine environments, at the edge of the encroaching sea, produced several sequences of both abrupt and gradual transition from continental wadi sediments to marginal marine evaporites in the studied area. These evaporites show well‐preserved textures indicative of relatively shallow‐brine pools. The high Br content of these evaporites indicates marine‐derived parent brines that were under the sporadic influence of freshening by meteoric water or replenishing seawater. However, the association of hopper and cornet textures denotes stratified brine that filled a relatively large pool and prevented rapid variations in the Br profile. Unstable basin conditions that triggered modification of parent brine chemistry prevailed in this basin and caused variable distribution patterns for different elements in the chloride units. The presence of sylvite and the absence of Mg‐sulphate/chlorides in the paragenetic sequence indicate SO₄−depleted parent brine in the studied sequence. Petrographic examinations along with geochemical analyses on these potash‐bearing halites reveal parental brines which were a mixture of seawater and CaCl₂‐rich brines. The source of CaCl₂‐rich brines is ascribed to the presence of local rift systems in the Great Kavir Basin up to the end of the Early Miocene. Copyright © 2007 John Wiley & Sons, Ltd.  相似文献   

Short contribution: Buried Canopic channel identified near Egypt's Nile delta coast with radar (SRTM) imagery     

Jean‐Daniel Stanley  Thomas F. Jorstad 《Geoarchaeology》2006,21(5):503-514

Shuttle Radar Topography Mission (SRTM) data, with ground‐based geologic investigations, define the geographic position of the relict Canopic channel in Egypt's NW Nile delta. Two sinuous channel segments south of Abu Qir Bay are observed on a radar image: a more sinuous trace (36 km in length) west of Idku lagoon, and an eastern one (˜20 km), reaching the lagoon's southeast corner. Sediment cores recovered along channel traces show sand‐rich deposits (to > 4 m thick) beneath the surface, in contrast with silty muds in areas away from channels. Historic and archaeological findings indicate that the Ptolemaic Roman city of Schedia once lay directly along the Canopic that channeled water from the 3rd to 2nd centuries B.C. until ˜5th century A.D., after which Nile water was displaced to the east via Bolbitic and, later, Rosetta branches. Identification of buried, but well‐defined, Canopic channels provides baselines for renewed archaeological exploration in this delta sector. © 2006 Wiley Periodicals, Inc.  相似文献   

Challenges in optics for Extremely Large Telescope instrumentation     

P. Span  F. M. Zerbi  C. J. Norrie  C. R. Cunningham  K. G. Strassmeier  A. Bianco  P. A. Blanche  M. Bougoin  M. Ghigo  P. Hartmann  L. Zago  E. Atad‐Ettedgui  B. Delabre  H. Dekker  M. Melozzi  B. Snÿders  R. Takke  D. D. Walker 《Astronomische Nachrichten》2006,327(7):649-673

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The Gyldén‐type problem revisited: More refined analytical solutions     

A. Pal  D. elaru  V. Mioc  C. Cucu‐Dumitrescu 《Astronomische Nachrichten》2006,327(4):304-308

We resume and consistently extend our previous researches concerning the Gyldén‐type problem (a two‐body problem with time‐dependent equivalent gravitational parameter). To approach most of the concrete astronomical situations to be modelled in this way, we consider a periodic small perturbation. For the nonresonant case, we present a second‐order analytical solution. For the resonant case, we adopt the most realistic astronomical situation: only one dominant term of the Hamiltonian. In this case we point out a fundamental model of resonance, common to every resonant situation, and, moreover, identical to the first fundamental model of resonance . Considering the simplest model of periodic change of the equivalent gravitational parameter, we .nd that all possible resonances are con.ned to the first fundamental model. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   

The Sloan Digital Sky Survey monitor telescope pipeline     

D.L. Tucker  S. Kent  M.W. Richmond  J. Annis  J.A. Smith  S.S. Allam  C.T. Rodgers  J.L. Stute  J.K. Adelman‐McCarthy  J. Brinkmann  M. Doi  D. Finkbeiner  M. Fukugita  J. Goldston  B. Greenway  J.E. Gunn  J.S. Hendry  D.W. Hogg  S.‐I. Ichikawa   . Ivezi&#x;  G.R. Knapp  H. Lampeitl  B.C. Lee  H. Lin  T.A. McKay  A. Merrelli  J.A. Munn  E.H. Neilsen  H.J. Newberg  G.T. Richards  D.J. Schlegel  C. Stoughton  A. Uomoto  B. Yanny 《Astronomische Nachrichten》2006,327(9):821-843

The photometric calibration of the Sloan Digital Sky Survey (SDSS) is a multi‐step process which involves data from three different telescopes: the 1.0‐m telescope at the US Naval Observatory (USNO), Flagstaff Station, Arizona (which was used to establish the SDSS standard star network); the SDSS 0.5‐m Photometric Telescope (PT) at the Apache Point Observatory (APO), NewMexico (which calculates nightly extinctions and calibrates secondary patch transfer fields); and the SDSS 2.5‐m telescope at APO (which obtains the imaging data for the SDSS proper). In this paper, we describe the Monitor Telescope Pipeline, MTPIPE, the software pipeline used in processing the data from the single‐CCD telescopes used in the photometric calibration of the SDSS (i.e., the USNO 1.0‐m and the PT). We also describe transformation equations that convert photometry on the USNO‐1.0m u ′g ′r ′i ′z ′ system to photometry the SDSS 2.5m ugriz system and the results of various validation tests of the MTPIPE software. Further, we discuss the semi‐automated PT factory, which runs MTPIPE in the day‐to‐day standard SDSS operations at Fermilab. Finally, we discuss the use of MTPIPE in current SDSS‐related projects, including the Southern u ′g ′r ′i ′z ′ Standard Star project, the u ′g ′r ′i ′z ′ Open Star Clusters project, and the SDSS extension (SDSS‐II). (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   

TAOS – The Taiwanese‐American Occultation Survey     

M. J. Lehner  C. Alcock  T. Axelrod  F. Bianco  Y.‐I. Byun  W.‐P. Chen  K. H. Cook  R. Dave  I. de Pater  J. Giammarco  S.‐K. King  T. Lee  J. Lissauer  S. L. Marshall  S. Mondal  T. Nihei  J. Rice  M. Schwamb  A. Wang  S.‐Y. Wang  C.‐Y. Wen  Z.‐W. Zhang 《Astronomische Nachrichten》2006,327(8):814-817

The Taiwanese‐American Occultation Survey (TAOS) seeks to determine the number and size spectrum for small (∼3 km) bodies in the Kuiper Belt. This will be accomplished by searching for the brief occultations of bright stars (R ∼ 14) by these objects. We have designed and built a special purpose photometric monitoring system for this purpose. TAOS comprises four 50 cm telescopes, each equipped with a 2048 × 2048 pixel CCD camera, in a compact array located in the central highlands of Taiwan. TAOS will monitor up to 2 000 stars at 5 Hz. The system went into scientific operation in the autumn of 2005. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   

Drop of coherence of the lower kilo‐Hz QPO in neutron stars: Is there a link with the innermost stable circular orbit?     

D. Barret  J.‐F. Olive  M. Coleman Miller 《Astronomische Nachrichten》2005,326(9):808-811

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Interactions between hot Jupiters and their host stars     

Pin‐Gao Gu  E. Shkolnik  Shu‐Lin Li  Xiao‐Wei Liu 《Astronomische Nachrichten》2005,326(10):909-912

A young hot Jupiter might have been tidally inflated beyond its Roche radius when its orbit was being circularized. This scenario has the potential to explain a couple of solid or tentative observations such as a pile‐up of hot Jupiters around 0.04‐0.05 AU, the mass‐period correlation of transiting planets, as well as the existence of hot Neptunes. Other scenarios such as tidal dissipation in a planet‐host star as well as the magnetic interaction will be also discussed. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献