Updated results of a search for main-belt comets using the Canada–France–Hawaii Telescope Legacy Survey     

Alyssa M. Gilbert  Paul A. Wiegert 《Icarus》2010,210(2):998-999

The results of a search for main-belt comets using Canada–France–Hawaii Telescope Legacy Survey data are updated. The remaining observations in the Very Wide segment of data, taken in the g’ or r’ filters, are visually inspected for cometary activity. The number of main-belt objects in the original and new data sets are 11,438 and 13,802, respectively, giving a total number of 25,240. This is the largest, and least biased, search for main-belt comets to date. One object is observed to show cometary activity, and a new upper limit for strongly active main-belt comets is derived to be 40 ± 18.  相似文献   

Homogeneous cosmological solutions of the Einstein equation     

Ernst Fischer 《Astrophysics and Space Science》2010,325(1):69-74

Homogeneous solutions in the framework of general relativity form the basis to understand the properties of gravitation on global scale. Presently favoured models describe the evolution of the universe by an expansion of space, governed by a scale function, which depends on a global time parameter. Dropping the restriction that a global time parameter exists, and instead assuming that the time scale depends on spatial distance, leads to static solutions, which exhibit no singularities, need no unobserved dark energy and which can explain the cosmological red shift without expansion. In contrast to the expanding world model energy is globally conserved. Observations of high energy emission and absorption from the intergalactic medium, which can scarcely be understood in the ‘concordance model’, find a natural explanation.  相似文献   

Precambrian Large Igneous Provinces (LIPs) and their dyke swarms: New insights from high-precision geochronology integrated with paleomagnetism and geochemistry     

Richard Ernst 《Precambrian Research》2010

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Large igneous province of about 1750 Ma in the Siberian Craton     

D. P. Gladkochub  S. A. Pisarevsky  R. Ernst  T. V. Donskaya  U. Söderlund  A. M. Mazukabzov  J. Hanes 《Doklady Earth Sciences》2010,430(2):168-171

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Tertiary alkaline Roztoky Intrusive Complex, České středohoří Mts., Czech Republic: petrogenetic characteristics     

Roman Skála  Jaromír Ulrych  Lukáš Ackerman  Emil Jelínek  Jaroslav Dostál  Ernst Hegner  Zdeněk Řanda 《International Journal of Earth Sciences》2014,103(5):1233-1262

The ?eské st?edoho?í Mts. is the dominant volcanic center of the Oh?e (Eger) rift zone. It hosts the Roztoky Intrusive Complex (RIC), which is made up of a caldera vent and intrusions of 33–28-Ma-old hypabyssal bodies of essexite–monzodiorite–sodalite syenite series accompanied by a radially oriented 30–25-Ma-old dike swarm comprising about 1,000 dikes. The hypabyssal rocks are mildly alkaline mostly foid-bearing types of mafic to intermediate compositions. The dike swarm consists of chemically mildly alkaline and rare strongly alkaline rocks (tinguaites). The geochemical signatures of the mildly alkaline hypabyssal and associated dike rocks of the RIC are consistent with HIMU mantle sources and contributions from lithospheric mantle. The compositional variations of essexite and monzodiorite can be best explained by fractional crystallization of parent magma without significant contributions of crustal material. On the other hand, the composition of monzosyenite, leuco-monzodiorite and sodalite syenite reflects fractional crystallization coupled with variable degrees of crustal assimilation. It is suggested that the parent magmas in the Oh?e rift were produced by an adiabatic decompression melting of ambient upper mantle in response to lithospheric extension associated with the Alpine Orogeny.  相似文献   

Stratigraphic status,age, and paleobathymetry of the Grey shale Member,Dalmiapuram Formation,Cauvery Basin,India     

R. Nagendra  P. Sathiyamoorthy  A. N. Reddy  Harry Gilbert  B. C. Jaiprakash 《Arabian Journal of Geosciences》2014,7(10):4133-4144

Grey shale Member of the Dalmiapuram Formation, Ariyalur Group, Cauvery Basin, India was studied for its stratigraphic position, age, and paleobathymetry with a re-look into the lithological relationship and foraminifer assemblages in the deepened limestone mine excavations at M/s Dalmia Cements, Dalmiapuram. Twenty grey shale samples from Kovandankurchchi (pit-4) and Kallakkudi mines yielded diversified calcareous, benthic, and rare index planktic foraminifera. The foraminiferal assemblages suggest a latest Albian age and middle neritic depositional conditions. The abundance of kaolinite and smectite clay minerals relate to warm/humid climate which corroborate with rising relative sea level during grey shale deposition. The grey shale occurs in patches within the marl bedded limestone member which exhibits cyclic deposition of limestone and marl. The limestone mine sections demonstrate that the grey shale forms part of basal marl bedded limestone, directly overlying the coral algal limestone. The present study demonstrates that the grey shale outcrops in Dalmiapuram Formation should be placed stratigraphically as part of marl bedded limestone. The member status for grey shale which is current usage stands discounted.  相似文献   

The non‐igneous genesis of angrites: Support from trace element distribution between phases in D'Orbigny     

María Eugenia Varela  Gero Kurat  Ernst Zinner  Peter Hoppe  Theodoros Ntaflos  Mikhail A. Nazarov 《Meteoritics & planetary science》2005,40(3):409-430

Abstract— D'Orbigny is an exceptional angrite. Chemically, it resembles other angrites such as Asuka‐881371, Sahara 99555, Lewis Cliff (LEW) 87051, and LEW 86010, but its structure and texture are peculiar. It has a compact and porous lithology, abundant glasses, augite‐bearing druses, and chemical and mineralogical properties that are highly unusual for igneous rocks. Our previous studies led us to a new view on angrites: they can possibly be considered as CAIs that grew to larger sizes than the ones we know from carbonaceous chondrites. Thus, angrites may bear a record of rare and special conditions in some part of the early solar nebula. Here we report trace element contents of D'Orbigny phases. Trace element data were obtained from both the porous and the compact part of this meteorite. We have confronted our results with the popular igneous genetic model. According to this model, if all phases of D'Orbigny crystallized from the same system, as an igneous origin implies, a record of this genesis should be expressed in the distribution of trace elements among early and late phases. Our results show that the trace element distribution of the two contemporaneous phases olivine and plagioclase, which form the backbone of the rock, seem to require liquids of different composition. Abundances of highly incompatible elements in all olivines, including the megacrysts, indicate disequilibrium with the bulk rock and suggest liquids very rich in these elements (>10,000 x CI), which is much richer than any fractional crystallization could possibly produce. In addition, trace element contents of late phases are incompatible with formation from the bulk system's residual melt. These results add additional severe constraints to the many conflicts that existed previously between an igneous model for the origin of angrites and the mineralogical and chemical observations. This new trace element content data, reported here, corroborate our previous results based on the shape, structure, mineralogy, chemical, and isotopic data of the whole meteorite, as well as on a petrographic and chemical composition study of all types of glasses and give strength to a new genetic model that postulates that D'Orbigny (and possibly all angrites) could have formed in the solar nebula under changing redox conditions, more akin to chondritic constituents (e.g., CAIs) than to planetary differentiated rock.  相似文献   

The Richfield LL3 chondrite     

Alan E. RUBIN  Paul BENOIT  Blaine REED  Otto EUGSTER  Ernst POLNAU 《Meteoritics & planetary science》1996,31(6):925-927

Abstract— Richfield is a moderately shocked (shock stage S4) LL3.7 genomict breccia find consisting mainly of light-colored recrystallized clasts and dark clasts exhibiting significant silicate darkening; a few impact-melt-rock clasts and LL5 chondrite clasts also occur. The cosmic-ray exposure age of 14.5 Ma is indistinguishable from the main exposure peak for LL chondrites (15 Ma). Although the exposure ages indicate little He loss, the gas-retention ages indicate high gas losses that must have occurred prior to or during ejection from the LL parent body.  相似文献   

Review of Late Jurassic-early Miocene sedimentation and plate-tectonic evolution of northern California: illuminating example of an accretionary margin     

Ernst  W. G. 《中国地球化学学报》2015,34(2):123-142

Acta Geochimica - Production of voluminous igneous arc rocks, high-pressure/low-temperature (HP/LT) metamafic rocks, westward relative migration of the Klamath Mountains province, and U–Pb...  相似文献   

Roche volume filling and the dissolution of open star clusters     

A. Ernst  P. Berczik  A. Just  T. Noel 《Astronomische Nachrichten》2015,336(6):577-589

From direct N‐body simulations we find that the dynamical evolution of star clusters is strongly influenced by the Roche volume filling factor. We present a parameter study of the dissolution of open star clusters with different Roche volume filling factors and different particle numbers. We study both Roche volume underfilling and overfilling models and compare with the Roche volume filling case. We find that in the Roche volume overfilling limit of our simulations two‐body relaxation is no longer the dominant dissolution mechanism but the changing cluster potential. We call this mechanism “mass‐loss driven dissolution” in contrast to “two‐body relaxation driven dissolution” which occurs in the Roche volume underfilling regime. We have measured scaling exponents of the dissolution time with the two‐body relaxation time. In this experimental study we find a decreasing scaling exponent with increasing Roche volume filling factor. The evolution of the escaper number in the Roche volume overfilling limit can be described by a log‐logistic differential equation. We report the finding of a resonance condition which may play a role for the evolution of star clusters and may be calibrated by the main periodic orbit in the large island of retrograde quasiperiodic orbits in the Poincaré surfaces of section. We also report on the existence of a stability curve which may be of relevance with respect to the structure of star clusters. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献