Possible variability of the magnetic field of T Tau

Using the Main Stellar Spectrograph of the 6-m Special Astrophysical Observatory telescope equipped with a polametric analyzer, we measured the longitudinal magnetic field component B_∥ for the T Tauri stars T Tau and AS 507 on January 16 and 18 and February 15, 2003. For both stars, we determined only the upper limits on B_∥ from photospheric lines: +15±30 G for T Tau and ?70±90 G for AS 507. The magnetic field of AS 507 was not measured previously, while B_∥ for T Tau is lower than its values that we obtained in 1996 and 2002 (B_∥?150±50G), suggesting that the longitudinal magnetic field component in the photosphere of T Tau is variable. We also measured the longitudinal magnetic field component for T Tau in the formation region of the He I 5876 Å emission line. We found B_∥ in this region to be ?+650, ?+350, and ?+1100 G on January 16, 18, and February 15, 2003, respectively. Our observations on January 18 and February 15 correspond to virtually the same phase of the star's rotation period, but the profiles of the He I 5876 Å line differ markedly on these two nights. Therefore, we believe that the threefold difference between the B_∥ values on these nights does not result from observational errors. We discuss the possible causes of the B_∥ variability in the photosphere and the magnetosphere of T Tau.     

STARE Results on a Single Field: Tens of New Pulsating Stars

We present preliminary results on variable stars of aSTARE's three month observational run centered at the Cygnus constellation.A total amount of aprox. 14000 stars with 9^2 FOV, have been analyzed to obtainlightcurves for each of these stars.The data spans for 90 nights.In this single field, we detect more that 40 stars withpulsation modes between 5 and 40 c/d, the vast mayoritypreviously unknown to be variables.     

Infrared photometry of the symbiotic novae V1016 Cyg and HM Sge in 1978–1999

The photometric JHKLM observations of the symbiotic novae V1016 Cyg and HM Sge in 1978–1999 are presented. Parameters of the cool stars themselves and the dust envelopes are estimated. The periods of 470±5 days (for V1016 Cyg) and 535±5 days (for HM Sge) are reliably determined from the entire set of our photometric J data for V1016 Cyg and HM Sge. In addition, monotonic light and color variations are observed on a time scale of several thousand days, with the increase in infrared brightness occurring with the simultaneous decrease in infrared color indices; i.e., the dust envelopes in which both components of the systems were embedded before the outburst of their hot sources in 1964 and 1975, respectively, had continued to disperse until late 1999. The amplitudes of these variations for HM Sge are almost twice those for V1016 Cyg. For HM Sge, the dust envelope reached a maximum density near JD 2447500 and then began to disperse. In the case of V1016 Cyg, a maximum density of the dust envelope was probably reached near JD 2444800, and its dispersal has been continuing for about 20 years. Thus, in both symbiotic novae, their dust envelopes reached a maximum density approximately eight years after the outburst of the hot component and then began to disperse. An analysis of the color-magnitude (J–K, J) diagram reveals that grains in the dust envelopes of V1016 Cyg and HM Sge are similar in their optical properties to impure silicates. The observed [J–K, K–L] color variations for the symbiotic novae under study can be explained in terms of the simple model we chose by variations in the Mira's photospheric temperature from 2400 to 3000 K and in the dust-envelope optical depth from 1 to 3 at a wavelength of 1.25 µm for a constant grain temperature. The observed J–K and K–L color indices for both symbiotic novae, while decreasing, tend to the values typical of Miras. The dust envelopes of both symbiotic novae are optically thick. The dust envelope around HM Sge is, on the average, twice as dense as that around V1016 Cyg; the Mira in V1016 Cyg is slightly cooler (~2800–2900 K) than that in HM Sge (~2600–2700 K). The dust-envelope density decreases as the Mira's temperature increases. The absolute bolometric magnitudes are $ - 5\mathop .\limits^m 1 \pm 0\mathop .\limits^m 15$ for V 1016 Cyg and $5\mathop .\limits^m 27 \pm 0\mathop .\limits^m 17$ for HM Sge. Their distances are 2.8±0.6 and 1.8±0.4 kpc, respectively; the luminosities and radii of their cool components (Miras) are 8.6×10³ L _⊙, 1×10⁴ L _⊙, 500R _⊙, and 540R _⊙. The radii of their dust envelopes are 1400R _⊙ and 1500R _⊙; the masses are (3?3.3) × 10^?5M_⊙ and (4?8) × 10^?5M_⊙ The dust envelope of V1016 Cyg disperses slower than that of HM Sge by almost a factor of 25.     

Phase Resolved High Speed Photometry and Spectroscopy of Pulsars

We describe the implementation of two High Time Resolution modes for ESO's new generation CCD controller FIERA. These new modes have been used to perform phase-resolved high speed photometry and spectroscopy of pulsars with the FORS instruments at the VLT.     

测井解释中岩性成份的最优化变尺度法分析

测井解释中岩性成份的分析是一个多参数的非线性反演问题，最优化变尺度法比较适合求解这一类问题，而且收敛速度快、效果好。这里主要讨论如何利用最优化变尺度法进行测井资料的岩性解释。首先介绍了最优化变尺度法的原理及其实现步骤，然后论述了最优化变尺度法在测井解释中的应用，包括目标函数的构制、岩性成份分析模型的建立，最后给出了最优化变尺度法在某井段岩性解释中的应用效果。     

煤田地震勘探中的可变线元采集技术及其应用

在复杂的地表地震地质条件及深部地震地质条件下,如何获得满足复杂地震勘探解释所需资料,有效地在资料采集费用和资料质量间作出优化选择显得尤为重要.为此,根据三维地震勘探面元叠加理论提出的可变线元采集技术,通过合理的布置激发点与接收点的位置,使得CMP点均匀分布在一个标准线元内.线元具有可分性,在不改变观测系统的前提下,可把标准线元调整到大小合适的尺寸,以便能够在增加覆盖次数和提高分辨率之间做出优化选择,为资料处理拓展空间,为资料解释提供多种不同覆盖次数的地震时间剖面.     

求解渗流自由面的变单元法

在分析其它计算渗流自由面方法的基础上提出了一种渗流分析的改变渗流系数的固定网格法,该法只需进行一次网格剖分,不人为干涉计算过程,完全通过程序迭代即可准确地求出自由面的边界。算例计算表明,该法具有程序处理简单、用户操作方便、计算结果准确等特性,一般迭代收敛很快。可应用于稳定和非稳定渗流自由面边界计算。     

电磁驱动可控震源在隧道探测中的应用

地震勘探对地下地质结构的调查是一种行之有效的方法。由于条件的限制,有些地区不适合采用炸药震源,而且炸药震源费用高、危险大。采用电磁驱动的高频可控震源,震源采用全新的电磁驱动方式,频率从10H z到1000H z,向地下发送可变频率振动。为验证高频可控震源野外工作的稳定性、可靠性、有效性,在鞍山东山隧道上进行了实际探测,与已知资料相比,得到了满意的结果。     

β分布的参数确定及其在岩土工程中的应用

对岩土工程中随机变量的空间概率特征进行了统计分析,介绍了确定β分布各参数的迭代方法,提出了经验公式简化迭代过程,有效地处理了随机变量分布范围的估计问题,并阐明了β分布在可靠度领域中的适用性。作为对比,对同一样本采用了其他分布进行拟合。分析结果表明,β分布拟合精度高于其他分布。     

遥感图象的典型变换方法及其在岩性识别中的应用

本文简要地介绍了遥感图象的典型变换方法的数学原理,提出了建立典型变换矩阵的两种方法:(1)从野外地物反射波谱数据的典型分析求出;(2)直接从遥感数字图象的亮度值数据求出。文中还讨论了地面反射波谱的典型分析结果与多光谱遥感图象亮度值典型分析结果之间的关系,论述了将地面波谱典型分析结果用于数字遥感图象处理的可行性。简述了在101图象处理系统上实现典型变换的步骤。最后给出两个用于岩性识别的实例。