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21.
Attila Mészáros 《Astrophysics and Space Science》1985,111(2):399-405
Graviton may, in principle, have a small non-zero mass. In this paper the relevant theory of the massive graviton with six polarisations is developed. The drastic impact of a non-zero mass of the graviton on cosmology is also illustrated. 相似文献
22.
23.
We have studied the influence of the magnetic helicity on solar particle propagation using the IMF data observed by the HELIOS spacecraft in the range 0.31–0.95 AU, during eight solar proton events. For this, we have derived power and helicity spectra of the turbulence of the magnetic field during the time of the events. These are used to compute the particle pitch-angle scattering coefficients according to the quasi-linear theory (QLT) treatment of particle propagation in turbulent magnetic fields. The results show that in all the cases the helicity effects are negligible and the particle's mean free paths deduced from the pitch-angle diffusion coefficients are the same regardless of whether or not helicity effects are included in the calculations. The computed mean free paths are quite different in each case.Deceased 10 April, 1995. 相似文献
24.
Valentin D. Ivanov G. Chauvin C. Foellmi M. Hartung N. Huélamo C. Melo D. Nürnberger M. Sterzik 《Astrophysics and Space Science》2006,304(1-4):247-249
The multiplicity of early-type stars is still not well established. The derived binary fraction is different for individual star forming regions, suggesting a connection with the age and the environment conditions. The few studies that have investigated this connection do not provide conclusive results. To fill in this gap, we started the first detailed adaptive-optic-assisted imaging survey of early-type field stars to derive their multiplicity in a homogeneous way. The sample has been extracted from the Hipparcos Catalog and consists of 341 BA-type stars within ∼300 pc from the Sun. We report the current status of the survey and describe a Monte-Carlo simulation that estimates the completeness of our companion detection. 相似文献
25.
Arnaud M. Aubourg E. Bareyre P. Br';ehin S. Caridroit R. de Kat J. Dispau G. Djidi K. Gros M. Lachièze-Rey M. Laigneau Y. Laurent B. Lesquoy E. Lavocat Ph. Magneville C. Mazeau B. Milsztajn A. Moscoso L. Pasquaud J. Paul B. Perrin P. Petibon J. Piret Y. Queinnec F. Rich J. Spiro M. de Trogoff J. Vigroux L. Zylberajch S. Ansari R. Cavalier F. Moniez M. Beaulieu J. P. Ferlet R. Grison Ph. Vidal-Madjar A. Adrianzyk G. Berger J. P. Burnage R. Delclite J. C. Kohler D. Magnan R. Richaud A. Guibert J. Moreau O. Tajahmady F. Baranne A. Maurice E. Prévôt L. Gry C. 《Experimental Astronomy》1994,4(3-4):265-278
A 20cm
2
CCD mosaic camera has been especially built to search for dark galactic halo objects by the gravitational microlensing effect. The sensitive area is made of 16 edge-buttable CCDs developped by Thomson-CTS, with 23×23 µm
2
pixels. The 35 kg camera housing and mechanical equipment is presented. The associated electronics and data acquisition system are described in a separate paper. The camera resides at the focal plane of a 40 cm, f/10, Ferson reflector. The instrument has been in operation since December 1991 at the La Silla Observatory (ESO). 相似文献
26.
Yannick Giraud-Héraud Jean Kaplan François De Volnay Martin Charling Tao Sylvaine Turck-Chièze 《Solar physics》1990,128(1):21-33
The Saclay solar evolution code is used to check the effect of WIMPs on solar evolution. In this paper we study the effects of various types of Cosmion-matter interactions, give constraints on the crosssections compatible with the measured neutrino rate of 2 SNU on chlorine, and relate these constraints to ongoing dark matter detection experiments.Unité associée au CNRS UA 280, F-75251 Paris Cedex 05, France.On leave from LPC, Collège de France. 相似文献
27.
The trans-Neptunian belt has been subject to a strong depletion that has reduced its primordial population by a factor of one hundred over the solar system's age. One by-product of such a depletion process is the existence of a scattered disk population in transit from the belt to other places, such as the Jupiter zone, the Oort cloud or interstellar space. We have integrated the orbits of the scattered disk objects (SDOs) so far discovered by 2500 Myr to study their dynamical time scales and the probability of falling in each of the end states mentioned above, paying special attention to their contribution to the Oort cloud. We found that their dynamical half-time is close to 2.5 Gyr and that about one third of the SDOs end up in the Oort cloud. 相似文献
28.
Guinevere Kauffmann Timothy M. Heckman Simon D. M. White Stéphane Charlot Christy Tremonti Jarle Brinchmann Gustavo Bruzual Eric W. Peng Mark Seibert Mariangela Bernardi Michael Blanton Jon Brinkmann Francisco Castander Istvan Csábai Masataka Fukugita Zeljko Ivezic Jeffrey A. Munn Robert C. Nichol Nikhil Padmanabhan Aniruddha R. Thakar David H. Weinberg Donald York 《Monthly notices of the Royal Astronomical Society》2003,341(1):33-53
29.
Himalayan magmatism and porphyry copper–molybdenum mineralization in the Yulong ore belt, East Tibet
Summary ?The NW–SE-trending Yulong porphyry Cu–Mo ore belt, situated in the Sanjiang0 area of eastern Tibet, is approximately 400 km
long and 35 to 70 km wide. Complex tectonic and magmatic processes during the Himalayan epoch have given rise to favorable
conditions for porphyry-type Cu–Mo mineralization.
Porphyry masses of the Himalayan epoch in the Yulong ore belt are distributed in groups along regional NW–SE striking tectonic
lineaments. They were emplaced mainly into Triassic and Lower Permian sedimentary-volcanic rocks. K–Ar und U–Pb isotopic datings
give an intrusion age range of 57–26 Ma. The porphyries are mainly of biotite monzogranitic and biotite syenogranitic compositions.
Geological and geochemical data indicate that the various porphyritic intrusions in the belt had a common or similar magma
source, are metaluminous to peraluminous, Nb–Y–Ba-depleted, I-type granitoids, and belong to the high-K calc-alkaline series.
Within the Yulong subvolcanic belt a number of porphyry stocks bear typical porphyry type Cu–Mo alteration and mineralization.
The most prominent porphyry Co–Mo deposits include Yulong, Malasongduo, Duoxiasongduo, Mangzong and Zhanaga, of which Yulong
is one of the largest porphyry Cu (Mo) deposits in China with approximately 8 × 106 tons of contained Cu metal. Hydrothermal alteration at Yulong developed around a biotite–monzogranitic porphyry stock that
was emplaced within Upper Triassic limestone, siltstone and mudstone. The earliest alteration was due to the effects of contact
metamorphism of the country rocks and alkali metasomatism (potassic alteration) within and around the porphyry body. The alteration
of this stage was accompanied by a small amount of disseminated and veinlet Cu–Mo sulfide mineralization. Later alteration–mineralization
zones form more or less concentric shells around the potassic zone, around which are distributed a phyllic or quartz–sericite–pyrite
zone, a silicification and argillic zone, and a propylitic zone.
Fluid inclusion data indicate that three types of fluids were involved in the alteration–mineralization processes: (1) early
high temperature (660–420 °C) and high salinity (30–51 wt% NaCl equiv) fluids responsible for the potassic alteration and
the earliest disseminated and/or veinlet Cu–Mo sulfide mineralization; (2) intermediate unmixed fluids corresponding to phyllic
alteration and most Cu–Mo sulfide mineralization, with salinities of 30–50 wt% NaCl equiv and homogenization temperatures
of 460–280 °C; and (3) late low to moderate temperature (300–160 °C) and low salinity (6–13 wt% NaCl equiv) fluids responsible
for argillic and propylitic alteration. Hydrogen and oxygen isotopic studies show that the early hydrothermal fluids are of
magmatic origin and were succeeded by increasing amounts of meteoric-derived convective waters. Sulfur isotopes also indicate
a magmatic source for the sulfur in the early sulfide mineralization, with the increasing addition of sedimentary sulfur outward
from the porphyry stock.
Received August 29, 2001; revised version accepted May 1, 2002
Published online: November 29, 2002 相似文献
30.
Gérard Daigne Patrick Charlot Christine Ducourant Jean-François Lestrade 《Astrophysics and Space Science》2003,286(1-2):255-260
The question of positioning the optical counterparts of the ICRF quasars is outlined in the perspective of future space astrometry
missions, which ultimately will bring a new realization of the ICRS in the optical range. Ground-based interferometry with
a dual-field observing mode (PRIMA/VLTI),together with the missions DIVA and FAME, will have a key role in building an extragalactic
reference frame in the optical/near-IR range with about the same accuracy as that of the present (VLBI) primary frame.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献