A Possible 456-Day Optical Period of OQ 530     

Yi Liu Juan Li Jun-Hui Fan 《中国天文和天体物理学报》2007,7(3):380-388

The post-1994observationsof the blazar OQ 530 in optical BV RI bands, and radio observations at 22GHz and 37GHz were collected. The date compensated discrete Fourier transform (DCDFT) and CLEANest methods were used to search for possible periodicities. Two possible periods of 456±100 days and 258±29 days were found in the optical bands. The existence of possible correlations between the optical and radio emissions was investigated by means of discrete correlation function (DCF) analysis, and no significant correlation was found. Some possible mechanisms for the periodic variability are discussed.  相似文献   

峨边彝族自治县沙坪镇羊竹坝崩塌地质环境条件及危石稳定性评价     

《四川地质学报》2022,(Z2):51-54

勘查区位于大渡河右岸近河床斜坡地带,属构造剥蚀及河流侵蚀低山地貌。通过对沙坪镇羊竹坝崩塌地质环境条件的研究,同时对该区危石稳定性进行了评价,认为区内地质灾害的类型主要为危石崩塌。危石区(单体)在持续降雨或地震的情况下多处于欠稳定状态,产生失稳破坏的可能性大。因此对工作区进行治理十分必要。  相似文献   

鄂尔多斯盆地西南部上古生界储层裂缝研究     

王倩  候玢池  张琦 《地下水》2015,(2)

裂缝的发育不仅可以提高基质渗透率,增大油气产量,而且可能成为油气二次运移的主要通道,因此定量评价储层(尤其是致密砂岩储层)的裂缝频率、发育规模和空间分布是十分必要的,通过岩心观察、薄片分析及测井资料解释等表明,研究区盒8、山1、山2段裂缝较为发育,以水平裂缝和高角度近垂直裂缝为主;约90%的裂缝为有效裂缝,显示气层或干层;约30%的裂缝产出层段为气层和含气层,可见宏观裂缝的发育为油气富集提供了良好的运移通道。成像测井显示,研究区微裂缝发育也较为广泛,以垂直裂缝为主,为天然气向上运移提供了通道。  相似文献   

EGUP与黑洞熵的修正值     

白吉龙  温廷敦 《天文学报》2015,56(1):1-6

目前,人们对黑洞Bekenstein-Hawking熵的量子修正值产生了极大的兴趣,尤其是黑洞熵对数修正项的系数.在广义不确定关系(GUP)的基础上,通过引入了推广的广义不确定关系(EGUP),运用面积定理计算了3类时空的黑洞熵的修正值,得到的黑洞熵的修正项的系数是正的.这种计算方法不仅对单视界时空适用,而且对有内视界的黑洞时空依然成立,并且在EGUP基础上计算出黑洞熵的修正值.相比GUP基础上得到的黑洞熵,EGUP可以应用于大尺度时空下,所以应用范围更广.此计算方法简洁明了,物理意义明确,可为黑洞熵对数修正值系数的确定提供参考.  相似文献   

Structure and evolution of magnetic fields associated with solar eruptions     

Haimin Wang  Chang Liu 《天文和天体物理学研究(英文版)》2015,(2):145-174

This paper reviews the studies of solar photospheric magnetic field evolution in active regions and its relationship to solar flares. It is divided into two topics, the magnetic structure and evolution leading to solar eruptions and rapid changes in the photospheric magnetic field associated with eruptions. For the first topic, we describe the magnetic complexity, new flux emergence, flux cancelation, shear motions, sunspot rotation and magnetic helicity injection, which may all contribute to the storage and buildup of energy that trigger solar eruptions. For the second topic, we concentrate on the observations of rapid and irreversible changes of the photospheric magnetic field associated with flares, and the implication on the restructuring of the three-dimensional magnetic field. In particular, we emphasize the recent advances in observations of the photospheric magnetic field, as state-of-the-art observing facilities(such as Hinode and Solar Dynamics Observatory) have become available. The linkages between observations, theories and future prospectives in this research area are also discussed.  相似文献   

The inner solar system cratering record and the evolution of impactor populations   总被引：1，自引：0，他引：1  

Robert G.Strom  Renu Malhotra  Zhi-Yong Xiao  Takashi Ito  Fumi Yoshida  Lillian R Ostrach 《天文和天体物理学研究(英文版)》2015,(3):407-434

We review previously published and newly obtained crater size-frequency distributions in the inner solar system. These data indicate that the Moon and the terrestrial planets have been bombarded by two populations of objects. Population 1,dominating at early times, had nearly the same size distribution as the present-day asteroid belt, and produced heavily cratered surfaces with a complex, multi-sloped crater size-frequency distribution. Population 2, dominating since about 3.8–3.7 Gyr,had the same size distribution as near-Earth objects(NEOs) and a much lower impact flux, and produced a crater size distribution characterized by a differential –3single-slope power law in the crater diameter range 0.02 km to 100 km. Taken together with the results from a large body of work on age-dating of lunar and meteorite samples and theoretical work in solar system dynamics, a plausible interpretation of these data is as follows. The NEO population is the source of Population 2 and it has been in near-steady state over the past ～ 3.7–3.8 Gyr; these objects are derived from the main asteroid belt by size-dependent non-gravitational effects that favor the ejection of smaller asteroids. However, Population 1 was composed of main belt asteroids ejected from their source region in a size-independent manner, possibly by means of gravitational resonance sweeping during orbit migration of giant planets;this caused the so-called Late Heavy Bombardment(LHB). The LHB began some time before ～3.9 Gyr, peaked and declined rapidly over the next ～ 100 to 300 Myr,and possibly more slowly from about 3.8–3.7 Gyr to ～2 Gyr. A third crater population(Population S) consisted of secondary impact craters that can dominate the cratering record at small diameters.  相似文献   

Optical observations of the broad-lined type Ic supernova SN 2012ap     

Zheng Liu  Xu-Lin Zhao  Fang Huang  Xiao-Feng Wang  Tian-Meng Zhang  Jun-Cheng Chen  Tong-Jie Zhang 《天文和天体物理学研究(英文版)》2015,(2):225-236

The optical observations of the type Ic supernova(SN Ic) SN 2012 ap in NGC 1729 are presented. A comparison with other SNe Ic indicates that SN 2012 ap is highly reddened(with E(B- V)host～0.8 mag) and may represent one of the most luminous SNe Ic ever observed, with an absolute V-band peak magnitude of ～-19.3±0.5 mag after extinction correction. The near-maximum-light spectrum shows wide spectral features that are typical of broad-lined SNe Ic. One interesting feature in the spectrum is the appearance of some narrow absorption features that can be attributed to the diffuse interstellar bands, consistent with the large reddening inferred from the photometric method. Based on the light curves and the spectral data, we estimate that SN 2012 ap produced a56 Ni mass of ～ 0.3 ± 0.1M in the explosion, with an ejecta mass of 2.4+0.7-0.7M and a kinetic energy of E5K= 1.1+0.4-0.4× 102 erg. The properties of its progenitor are also briefly discussed.  相似文献   

Estimation of transition redshift based on Reinsch splines     

Guo-Dong L  De-Zi Liu  Shuo Yuan  Tong-Jie Zhang 《天文和天体物理学研究(英文版)》2015,(3):305-312

Many schemes have been proposed to define a model-independent constraint on cosmological dynamics, such as the nonparametric dark energy equation of state ω(z) or the deceleration parameter q(z). These methods usually contain derivatives with respect to observational data with noise. However, there can be large uncertainties when one estimates values with numerical differentiation, especially when noise is significant. We introduce a global numerical differentiation method, first formulated by Reinsch, which is smoothed by cubic spline functions, and apply it to the estimation of the transition redshift ztwith a simulated expansion rate E(z) based on observational Hubble parameter data. We also discuss some deficiencies and limitations of this method.  相似文献   

An accreting low magnetic field magnetar for the ultraluminous X-ray source in M82     

Hao Tong 《天文和天体物理学研究(英文版)》2015,(4):517-524

One ultraluminous X-ray source in M82 has recently been identified as an accreting neutron star(named Nu STAR J095551+6940.8).It has a super-Eddington luminosity and is spinning up.An aged magnetar is more likely to be a low magnetic field magnetar.An accreting low magnetic field magnetar may explain both the superEddington luminosity and the rotational behavior of this source.Considering the effect of beaming,the spin-up rate is understandable using the traditional form of accretion torque.The transient nature and spectral properties of M82 X-2 are discussed.The theoretical range of periods for accreting magnetars is provided.Three observational appearances of accreting magnetars are summarized.  相似文献   

建筑工地临时设施及其防雷安全检测     

敖国天 《贵州气象》2013,(5)

在新建项目防雷装置现场跟踪检测中,都是按照设计审核意见和GB50057-2010《建筑物防雷设计规范》规定进行检测,多数情况下忽略了现场工地塔吊、脚手架、现场工房、旗杆的防雷接地检测,以致这些位置出现雷击事故后才引起注意.通过总结几年来建筑工地的检测工作经验,提出了新建项目中这几个地方防雷检测应注意的事项.  相似文献