A Model for the Quiescent Phase of the Recurrent Nova U Scorpii     

Hachisu I  Kato M  Kato T  Matsumoto K  Nomoto K 《The Astrophysical journal》2000,534(2):L189-L192

A theoretical light curve is constructed for the quiescent phase of the recurrent nova U Scorpii in order to resolve the existing distance discrepancy between the outbursts (d approximately 6 kpc) and the quiescences (d approximately 14 kpc). Our U Sco model consists of a very massive white dwarf (WD), an accretion disk (ACDK) with a flaring-up rim, and a lobe-filling, slightly evolved, main-sequence star (MS). The model properly includes an accretion luminosity of the WD, a viscous luminosity of the ACDK, and a reflection effect of the MS and the ACDK irradiated by the WD photosphere. The B light curve is well reproduced by a model of 1.37 M middle dot in circle WD + 1.5 M middle dot in circle MS (0.8-2.0 M middle dot in circle MS is acceptable) with an ACDK having a flaring-up rim and the inclination angle of the orbit i approximately 80&j0;. The calculated color is rather blue (B-V approximately 0.0) for a suggested mass accretion rate of 2.5x10-7 M middle dot in circle yr-1, thus indicating a large color excess of E(B-V) approximately 0.56 with the observational color of B-V=0.56 in quiescence. Such a large color excess corresponds to an absorption of AV approximately 1.8 and AB approximately 2.3, which reduces the distance to 6-8 kpc. This is in good agreement with the distance estimation of 4-6 kpc for the latest outburst. Such a large intrinsic absorption is very consistent with the recently detected period change of U Sco, which is indicating a mass outflow of approximately 3x10-7 M middle dot in circle yr-1 through the outer Lagrangian points in quiescence.  相似文献   

Nucleosynthesis and Clump Formation in a Core-Collapse Supernova     

Kifonidis K  Plewa T  Janka H  Müller E 《The Astrophysical journal》2000,534(2):L123-L126

  相似文献   

The Properties of Supernova 1997cy Associated with GRB 970514     

Turatto M  Suzuki T  Mazzali PA  Benetti S  Cappellaro E  Danziger IJ  Nomoto K  Nakamura T  Young TR  Patat F 《The Astrophysical journal》2000,534(1):L57-L61

The extraordinary SN 1997cy associated with GRB 970514 has been observed photometrically and spectroscopically for nearly 2 yr. At the time of discovery, SN 1997cy was the brightest supernova (SN) ever observed (MV相似文献   

On the Radii of Close-in Giant Planets     

Burrows A  Guillot T  Hubbard WB  Marley MS  Saumon D  Lunine JI  Sudarsky D 《The Astrophysical journal》2000,534(1):L97-L100

The recent discovery that the close-in extrasolar giant planet HD 209458b transits its star has provided a first-of-its-kind measurement of the planet's radius and mass. In addition, there is a provocative detection of the light reflected off of the giant planet tau Bootis b. Including the effects of stellar irradiation, we estimate the general behavior of radius/age trajectories for such planets and interpret the large measured radii of HD 209458b and tau Boo b in that context. We find that HD 209458b must be a hydrogen-rich gas giant. Furthermore, the large radius of a close-in gas giant is not due to the thermal expansion of its atmosphere but to the high residual entropy that remains throughout its bulk by dint of its early proximity to a luminous primary. The large stellar flux does not inflate the planet but retards its otherwise inexorable contraction from a more extended configuration at birth. This implies either that such a planet was formed near its current orbital distance or that it migrated in from larger distances (>/=0.5 AU), no later than a few times 107 yr of birth.  相似文献   

ASCA Observation of the Quiescent X-Ray Counterpart to SGR 1627-41     

Hurley K  Strohmayer T  Li P  Kouveliotou C  Woods P  van Paradijs J  Murakami T  Hartmann D  Smith I  Ando M  Yoshida A  Sugizaki M 《The Astrophysical journal》2000,528(1):L21-L23

We present a 2-10 keV ASCA observation of the field around the soft gamma repeater SGR 1627-41. A quiescent X-ray source, whose position is consistent both with that of a recently discovered BeppoSAX X-ray source and with the Interplanetary Network localization for this soft gamma repeater, was detected in this observation. In 2-10 keV X-rays, the spectrum of the X-ray source may be fit equally well by a power-law, blackbody, or bremsstrahlung function, with unabsorbed flux approximately 5x10-12 ergs cm-2 s-1. We do not confirm a continuation of a fading trend in the flux, and we find no evidence for periodicity, both of which were noted in the earlier BeppoSAX observations.  相似文献   

An Internally Consistent Thermodynamic Model for the System CaO-MgO-Al2O3-SiO2 Derived Primarily from Phase Equilibrium Data     

Gasparik T 《The Journal of geology》2000,108(1):103-119

An internally consistent thermodynamic model for the subsolidus system CaO-MgO-Al2O3-SiO2 (CMAS) was developed and refined using primarily data from phase equilibrium experiments. The solution properties of pyroxenes and garnet were approximated with an ionic model, with independent mixing on adjacent crystallographic sites. This approach simplified the calculation of phase relations by allowing sequential calculation of the site occupancies. Enthalpy, entropy, and volume differences, nominally at 970 K, were derived for all participating phases by matching as closely as possible the experimentally observed phase relations. Although thermochemical measurements were not used directly in the refinement, the results were continuously monitored and compared with the thermochemical data to achieve a close match. The new model can be used to calculate phase diagrams for the CMAS system and its subsystems in the whole pressure range of the upper mantle. Simple empirical corrections for the effects of Na, Fe, Cr, etc., could potentially be introduced to make the model applicable to the thermobarometry of chemically complex mantle materials. Application of the new model to garnet lherzolite xenoliths from northern Lesotho and garnet peridotites from Norway supports the proposals for higher temperatures of the continental lithosphere.  相似文献   

利用步长模拟对青藏高原涡度方差测量法的质量评价   总被引：1，自引：0，他引：1  

S. Metzger  马耀明  T.Markkanen  M. G 《地球科学进展》2006,21(12):1260-1267

利用痕迹模拟方法对青藏高原两处地方涡度方差的测量数据进行了质量分析，揭示了其空间和时间结构。分析表明高达1/3的测量没有达到必要的数据正确假设。尽管这样对潜热、CO2、动量通量的测量基本通过测试，可以适用于基础研究，但是经常发现特定的风矢量违背基本假设条件。感热通量的测量允许使用不间断的连续测量法，然而由于局地地形的影响少量评估指数未能合理解释，但能够指示出组织结构及用于导出边界层中尺度流体模型假说。  相似文献   

哈萨克斯坦共和国地震学数据库简介     

E.H.努西波夫  A.B.日连科  C.B.涅姆切科夫  Б.М.阿希罗夫  Д.叶斯肯季罗夫  H.T.叶金别科娃  陈保华 《内陆地震》2007,21(3):287-288

建立哈萨克斯坦共和国地震学数据库是CASIN国际项目的一部分,应由中亚各国来共同完成。项目主要目的旨在建立地震学数据库,以作为今后减小哈萨克斯坦共和国地震危险性的工作基础。哈萨克斯坦共和国地震学数据库由下列子系统构成:1)文件输入子系统;2)信息检索和提交子系统;3)信息元数据存储子系统;4)档案库运行控制子系统;5)信息安全子系统。哈萨克斯坦共和国地震学数据库有以下功能:1)永久存储综合信息并上报和收集(记录)其他资料;2)存储数据和资料计算;3)电子文档的长期存储和管理;4)规定序号进行信息查询和文件的联机保证;5)信息统计和…  相似文献   

多变量线性回归的平均值概念及其在地学研究中的应用     

周卫健  陈茂柏  鲜锋  宋少华  武振坤  A. J. T. Jull  刘卫国 《中国科学D辑》2007,37(10):1392-1399

文章以实例阐述了多变量一元线性回归计算中的“平均值概念”. 作者根据“平均值概念”, 利用珊瑚δ¹⁸O比值重建了最近90年西沙表层海水盐度的变化历史,并运用洛川黄土¹⁰Be记录示踪了最近80 ka全球性的古地磁漂移事件, 从而阐明了“平均值概念”在地学数据分析中的重要意义及应用前景.  相似文献   

澳大利亚造山型金矿和侵入岩有关金矿系统流体包裹体资料和矿化过程的比较   总被引：8，自引：7，他引：8  

T.P.Memagh E.N.Bastrakov Khin Zaw A.S.Wygralak L.A.I.Wybom 《岩石学报》2007,23(1):21-32

We have examined the fluid inclusion data and fluid chemistry of Australian orogenic and intrusion-related gold deposits to determine if similar mineralization processes apply to both styles of deposits.The fluid inclusion data from the Yilgarn craton,the western subprovince of the Lachlan orogen,the Tanami,Tennant Creek and Pine Creek regions,and the Telfer gold mine show that mineralization involved fluids with broadly similar major chemical components(i.e.H_2O NaCl CO_2±CH_4±N_2).These deposits formed over a wide range of temperature-pressure conditions(<200 to>500℃,<100～400MPa).Low salinity, CO_2-bearing inclusions and low salinity aqueous inclusions occur in both systems but the main difference between these two types of deposits is that most intrusion-related gold deposits also contain at least one population of high-salinity aqueous brine.Oxygen and hydrogen isotope data for both styles of deposit usually cannot distinguish between a magmatic or metamorphic source for the ore-bearing fluids.However,sulfur and lead isotope data for the intrusion-related gold deposits generally indicate either a magmatic source or mixing between magmatic and sedimentary sources of fluid.The metamorphic geothermal gradients associated with intrusion-related gold deposits are characterized by low pressure,high temperature metamorphism and high crustal geothermal gradients of>30/km.Where amphibole breakdown occurs in a granite source region,the spatially related deposits are more commonly associated with Cu-Au deposits rather than Au-only deposits that are associated with lower temperature granites.The dominant processes thought to cause gold precipitation in both types of deposits are fluid-rock interaction(e.g.desulfidation)or phase separation.Consideration of the physical and chemical properties of the H_2O-NaCl-CO_2 system on the nature of gold precipitation mechanisms at different crustal levels infers different roles of chemical(fluid-rock interaction)versus rheological(phase separation and/or fluid mixing)host-rock controls on gold deposition.This also implies that at the site of deposition,similar precipitation mechanisms operate at similar crustal levels for both orogenic and intrusion-related gold deposits.  相似文献