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

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.     

The Properties of Supernova 1997cy Associated with GRB 970514

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

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.     

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

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.     

利用步长模拟对青藏高原涡度方差测量法的质量评价

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。     

模拟岩溶含水系统演化的耦合网络模型

提出一个数学模型以研究碳酸盐岩含水层由其原始状态到成熟岩溶含水系统的发展过程。模型由３个模块组成：（ａ）二维连续空隙水渗流模块,表示裂隙系统（“分散流”系统）,即岩溶空管道之间水性差而贮水性强的那部分岩体;（ｂ）非连续管道网络模块,模拟冉溶道内发生的层流、紊流运动和溶质运移过程;（ｃ）碳酸盐岩溶蚀模块。管道－裂隙系统模型的模拟结果表明,模拟那种复杂的、具有多种地下水补给方式的岩溶含水盆地的演化是可     

用微型干涉仪测地终端设备(MITES)测量基线的精度估计

<正> 1980年12月17日将轻便的MITES天线(见Bull.Geod.53,139—163,1979)设在Haystack天文台附近三座测量标志的顶部。这些天线获得了全球定位系统卫星(NAVSTAR/GPS)的射电干涉测量结果,经过分析后,便确定了这些测量标志之间的基线向量。     

二维付里叶变换

前言本文提出的二维付里叶变换的一些基本性质,重点放在用于模拟图象抽样和扫描处理的一些冲击函数。虽然本文所论述的只是用两个独立变量表示的函数,但稍经修改之后,其大多数的结论,都能推广到n维空间。 1.二维线性系统二维系统的输入和输出是两个独立变量的函数。在描图和图象处理系统中,通常,这两     

海洋资料系统

七十年代这十年间由于多种学科、多种船只和许多国家的研究计划给我们带来了广阔的海洋科学。若没有计算机,我们就无从整理这种计划所产生的空前未有的大量资料。尽管有了计算机,我们可能还不理解所收集到的这些资料。正如大会计划所总结的问题。“我们现在面临一个充满矛盾的时期。有些海洋学家认为必须使航海船上计算机的大小和能力不断升级……而另一些海洋学家则感到必须把海上的计算强度减少到最小并且利用标准电讯技术的方便在岸上完成更高级的处理。我们注意到一个研究机构的科学家使用另一个研究机构船只的倾向在增加。我们看到了