YNAO OpenIR
http://ir.ynao.ac.cn:80
中国科学院国家科学图书馆机构知识库Thu, 23 Nov 2017 09:25:15 GMT2017-11-23T09:25:15Z天医携手 悬壶问天——昆明医科大学附一院联手中科院云南天文台研究空间天气对人体活动影响
http://ir.ynao.ac.cn:80/handle/114a53/10185
题名: 天医携手 悬壶问天——昆明医科大学附一院联手中科院云南天文台研究空间天气对人体活动影响
作者: 董亮; 汪敏; 林隽; 高冠男; 郭少杰; 李雪松; 刘凌; 喻卓; 杨龙; 吴晖Mon, 20 Nov 2017 07:38:10 GMThttp://ir.ynao.ac.cn:80/handle/114a53/101852017-11-20T07:38:10Z为导航通信提供保障——太阳射电爆发干扰导航通信监测预报
http://ir.ynao.ac.cn:80/handle/114a53/10184
题名: 为导航通信提供保障——太阳射电爆发干扰导航通信监测预报
作者: 董亮; 汪敏; 林隽; 高冠男; 黄文耿; 刘四清; 屈会鹏; 陈旭东; 闫小娟; 敦金平Mon, 20 Nov 2017 07:29:34 GMThttp://ir.ynao.ac.cn:80/handle/114a53/101842017-11-20T07:29:34ZMerging of a CO WD and a He-rich WD to produce a type Ia supernovae
http://ir.ynao.ac.cn:80/handle/114a53/10183
题名: Merging of a CO WD and a He-rich WD to produce a type Ia supernovae
作者: Liu DD(刘栋栋); Wang B(王博); Wu CY(吴程远); Han ZW(韩占文)
摘要: Context. Although type Ia supernovae (SNe Ia) play a key role in astrophysics, the companions of the exploding carbon-oxygen white dwarfs (CO WDs) are still not completely identified. It has been suggested recently that a He-rich WD (a He WD or a hybrid HeCO WD) that merges with a CO WD may produce an SN Ia. This theory was based on the double-detonation model, in which the shock compression in the CO core caused by the surface explosion of the He-rich shell might lead to the explosion of the whole CO WD. However, so far, very few binary population synthesis (BPS) studies have been made on the merger scenario of a CO WD and a He-rich WD in the context of SNe Ia. Aims. We aim to systematically study the Galactic birthrates and delay-Time distributions of SNe Ia based on the merger scenario of a CO WD and a He-rich WD. Methods. We performed a series of Monte Carlo BPS simulations to investigate the properties of SNe Ia from the merging of a CO WD and a He-rich WD based on the Hurley rapid binary evolution code. We also considered the influence of different metallicities on the final results. Results. From our simulations, we found that no more than 15% of all SNe Ia stem from the merger scenario of a CO WD and a He-rich WD, and their delay times range from ~110 Myr to the Hubble time. This scenario mainly contributes to SN Ia explosions with intermediate and long delay times. The present work indicates that the merger scenario of a CO WD and a He-rich WD can roughly reproduce the birthrates of SN 1991bg-like events, and cover the range of their delay times. We also found that SN Ia birthrates from this scenario would be higher for the cases with low metallicities.Mon, 20 Nov 2017 07:07:25 GMThttp://ir.ynao.ac.cn:80/handle/114a53/101832017-11-20T07:07:25ZQuiescent photometric modulations of two low-inclination cataclysmic variables KZ Geminorum and TW Virginis
http://ir.ynao.ac.cn:80/handle/114a53/10182
题名: Quiescent photometric modulations of two low-inclination cataclysmic variables KZ Geminorum and TW Virginis
作者: Dai ZB(戴智斌); Szkody, Paula; Taani, Ali; Garnavich, Peter M; Kennedy, Mark
摘要: Aims. The quiescent periodic photometric modulations of two low-inclination cataclysmic variables observed in Kepler K2 Campaigns 0 and 1, KZ Gem and TW Vir, are investigated. Methods. A phase-correcting method was successfully used to detect the orbital modulations of KZ Gem and TW Vir and improve their orbital periods. The light curve morphologies of both CVs were further analyzed by defining flux ratios and creating colormaps. Results. KZ Gem shows ellipsoidal modulations with an orbital period of 0.22242(1) day, twice the period listed in the updated RK catalogue (Edition 7.24). With this newly determined period, KZ Gem is no longer a CV in the period gap, but a long-period CV. A part of the quiescent light curve of TW Vir that had the highest stability was used to deduce its improved orbital period of 0.182682(3) day. The flat patterns shown in the colormaps of the flux ratios for KZ Gem demonstrate the stability of their orbital modulations, while TW Vir show variable orbital modulations during the K2 datasets. In TW Vir, the single versus double-peaked nature of the quiescent orbital variations before and after superoutburst may be related to the effect of the superoutburst on the accretion disk. Mon, 20 Nov 2017 03:31:43 GMThttp://ir.ynao.ac.cn:80/handle/114a53/101822017-11-20T03:31:43Z3～5μm红外天空亮度测量的多元定标模型
http://ir.ynao.ac.cn:80/handle/114a53/10181
题名: 3～5μm红外天空亮度测量的多元定标模型
作者: 赵志军; 许方宇; 高玲; 郭杰; 徐世春; 刘忠
摘要: 传统一元定标法测量红外天空亮度,面临诸多困难,如测量易受环境温度变化影响、仪器动态范围不足等。提出增加积分时间为自变量的二元定标模型,解决了仪器动态范围不足的问题;然后通过改变环境温度的系列实验,掌握了二元定标模型中仪器辐射随环境温度变化的规律;基于此,提出再增加环境温度为自变量的三元定标模型。实验数据表明,三元模型与实测数据拟合程度很高,相关系数为1.000,模型参数a、b、d,95%置信度的相对不确定度均小于0.82%,当环境保持某一温度不变时,三元模型退化为二元模型,各模型参数稳定,其相对偏差小于0.6%。最后,通过红外天空亮度实测,验证并比较了三元和二元定标模型;结果表明,三元模型定标测量法使用条件宽泛,既扩大了仪器动态范围,又不受环境温度变化影响;更重要的是,不再需要现场定标,提高了测量精度和测试效率。
摘要: The traditional univariate calibration method used in measuring infrared sky brightness is confronted with many issues, and two main issues are the insufficient dynamic response of the measuring instruments as well as the influence of the ambient temperature on the measurement result. In order to extend the dynamic response of the measuring instruments, a bivariate calibration model at the constant temperature was demonstrated in the paper, and its independent variables were radiance and exposure time. Then with the experiment data acquired in many temperatures, the variation of the bivariate calibration model in different temperature was analyzed. Thus trivariate calibration model was presented at the last part, and the goodness of the fit of the model and the experiment data was best. R -square is 1.000, and the relevant uncertainties in 95% confidence degree of a, b and d, parameters of the trivariate calibration model, were all less than 0.82%, trivariate model can be degraded to bivariate at some certain temperature, the deviation of all of parameters of degraded model were less than 0.6%; Finally, with the outfield experiment of infrared sky brightness, bivariate and trivariate calibration model were validated and compared. The benefit of this trivariate calibration model is that it can extend the dynamic response of the measuring instruments, and the precision of its measuring result is not affected by the variation of ambient temperature. Hence this model can be widely used and can achieve high-precision and highefficiency measurement without in-situ calibration.Fri, 17 Nov 2017 08:05:05 GMThttp://ir.ynao.ac.cn:80/handle/114a53/101812017-11-17T08:05:05ZSynchrotron Spectrum of Fast Cooling Electrons in GRBs
http://ir.ynao.ac.cn:80/handle/114a53/10180
题名: Synchrotron Spectrum of Fast Cooling Electrons in GRBs
作者: Zhao XH(赵晓红); Bai JM(白金明)
摘要: We discuss the synchrotron emission of fast cooling electrons in shocks. The fast cooling electrons behind the shocks can generate a position-dependent inhomogeneous electron distribution if they do not have enough time to mix homogeneously. This can lead to a very different synchrotron spectrum in low-frequency bands from that in the homogeneous case, due to the synchrotron absorption. In this paper, we calculate the synchrotron spectrum in the inhomogeneous case in a gamma-ray burst (GRB). Both the forward shock and the reverse shock are considered. We find that for the reverse shock dominated case, we would expect a "reverse shock bump" in the low-frequency spectrum. The spectral bump is due to the combination of synchrotron absorption in both the forward and reverse shock regions. In the low frequencies the forward shock spectrum has two unconventional segments, with spectral slopes of less than or similar to 1 and 11/8. The slope of 11/8 has been found by some authors, while the slope of less than or similar to 1 is new and due to the approximately constant electron temperature in the optically thick region. In the future, simultaneous observations in multiple bands (especially in the low-frequency bands) in the GRB early afterglow or prompt emission phases will possibly reveal these spectral characteristics and enable us to identify the reverse shock component and distinguish between the forward and reverse shock emissions. This also may be a method with which to diagnose the electron distribution status (homogeneous or inhomogeneous) after fast cooling in the relativistic shock region.Thu, 16 Nov 2017 07:39:42 GMThttp://ir.ynao.ac.cn:80/handle/114a53/101802017-11-16T07:39:42ZA NON-PARAMETRIC APPROACH TO CONSTRAIN THE TRANSFER FUNCTION IN REVERBERATION MAPPING
http://ir.ynao.ac.cn:80/handle/114a53/10179
题名: A NON-PARAMETRIC APPROACH TO CONSTRAIN THE TRANSFER FUNCTION IN REVERBERATION MAPPING
作者: Li, Yan-Rong; Wang, Jian-Min; Bai JM(白金明)
摘要: Broad emission lines of active galactic nuclei stem from a spatially extended region (broad-line region, BLR) that is composed of discrete clouds and photoionized by the central ionizing continuum. The temporal behaviors of these emission lines are blurred echoes of continuum variations (i.e., reverberation mapping, RM) and directly reflect the structures and kinematic information of BLRs through the so-called transfer function (also known as the velocity-delay map). Based on the previous works of Rybicki and Press and Zu et al., we develop an extended, non-parametric approach to determine the transfer function for RM data, in which the transfer function is expressed as a sum of a family of relatively displaced Gaussian response functions. Therefore, arbitrary shapes of transfer functions associated with complicated BLR geometry can be seamlessly included, enabling us to relax the presumption of a specified transfer function frequently adopted in previous studies and to let it be determined by observation data. We formulate our approach in a previously well-established framework that incorporates the statistical modeling of continuum variations as a damped random walk process and takes into account long-term secular variations which are irrelevant to RM signals. The application to RM data shows the fidelity of our approach.Thu, 16 Nov 2017 07:33:56 GMThttp://ir.ynao.ac.cn:80/handle/114a53/101792017-11-16T07:33:56ZCyclic Period Oscillation of the Eclipsing Dwarf Nova DV UMa
http://ir.ynao.ac.cn:80/handle/114a53/10178
题名: Cyclic Period Oscillation of the Eclipsing Dwarf Nova DV UMa
作者: Han, Z. -T; Qian SB(钱声帮); Irina, Voloshina; Zhu, L. -Y
摘要: DV UMa is an eclipsing dwarf nova with an orbital period of similar to 2.06 hr, which lies just at the bottom edge of the period gap. To detect its orbital period changes, we present 12 new mid-eclipse times by using our CCD photometric data and archival data. The latest version of the O-C diagram, combined with the published mid-eclipse times in quiescence, and spanning similar to 30 years, was obtained and analyzed. The best fit to those available eclipse timings shows that the orbital period of DV UMa is undergoing a cyclic oscillation with a period of 17.58(+/- 0.52) years and an amplitude of 71.1(+/- 6.7) s. The periodic variation most likely arises from the light-travel-time effect via the presence of a circumbinary object, because the required energy to drive the Applegate mechanism is too high in this system. The mass of the unseen companion was derived as M-3 sin i' = 0.025(+/- 0.004) M.. If the third body is in the orbital plane (i.e., i' = i = 82 degrees.9) of the eclipsing pair, this would indicate it is a brown dwarf. This hypothetical brown dwarf is orbiting its host star at a separation of similar to 8.6 au in an eccentric orbit (e. = 0.44).Thu, 16 Nov 2017 07:06:04 GMThttp://ir.ynao.ac.cn:80/handle/114a53/101782017-11-16T07:06:04ZNUMERICAL INTEGRAL OF RESISTANCE COEFFICIENTS IN DIFFUSION
http://ir.ynao.ac.cn:80/handle/114a53/10177
题名: NUMERICAL INTEGRAL OF RESISTANCE COEFFICIENTS IN DIFFUSION
作者: Zhang QS(张钱生)
摘要: The resistance coefficients in the screened Coulomb potential of stellar plasma are evaluated to high accuracy. I have analyzed the possible singularities in the integral of scattering angle. There are possible singularities in the case of an attractive potential. This may result in a problem for the numerical integral. In order to avoid the problem, I have used a proper scheme, e.g., splitting into many subintervals where the width of each subinterval is determined by the variation of the integrand, to calculate the scattering angle. The collision integrals are calculated by using Romberg's method, therefore the accuracy is high (i.e., similar to 10(-12)). The results of collision integrals and their derivatives for -7 <= psi <= 5 are listed. By using Hermite polynomial interpolation from those data, the collision integrals can be obtained with an accuracy of 10(-10). For very weakly coupled plasma (psi >= 4.5), analytical fittings for collision integrals are available with an accuracy of 10(-11). I have compared the final results of resistance coefficients with other works and found that, for a repulsive potential, the results are basically the same as others'; for an attractive potential, the results in cases of intermediate and strong coupling show significant differences. The resulting resistance coefficients are tested in the solar model. Comparing with the widely used models of Cox et al. and Thoul et al., the resistance coefficients in the screened Coulomb potential lead to a slightly weaker effect in the solar model, which is contrary to the expectation of attempts to solve the solar abundance problem.Thu, 16 Nov 2017 06:59:11 GMThttp://ir.ynao.ac.cn:80/handle/114a53/101772017-11-16T06:59:11ZTHE SHAPE OF SOLAR CYCLES DESCRIBED BY A SIMPLIFIED BINARY MIXTURE OF GAUSSIAN FUNCTIONS
http://ir.ynao.ac.cn:80/handle/114a53/10176
题名: THE SHAPE OF SOLAR CYCLES DESCRIBED BY A SIMPLIFIED BINARY MIXTURE OF GAUSSIAN FUNCTIONS
作者: Li FY(李富羽); Xiang, N. B.; Kong, D. F.; Xie, J. L.
摘要: Sunspot cycles usually present a double-peak structure. This work is devoted to using a function to describe the shape of sunspot cycles, including bimodal cycles, and we find that the shape of sunspot cycles can be described by a binary mixture of Gaussian functions with six parameters, two amplitudes, two gradients of curve, and two rising times, and the parameters could be reduced to three. The fitting result of this binary mixture of Gaussian functions is compared with some other functions used previously in the literature, and this function works pretty well, especially at cycle peaks. It is worth mentioning that the function can describe well the shape of those sunspot cycles that show double peaks, and it is superior to the binary mixture of the Laplace functions that was once utilized. The Solar Influences Data Analysis Center, on behalf of the World Data Center, recently issued a new version (version 2) of sunspot number. The characteristics of sunspot cycles are investigated, based on the function description of the new version.Thu, 09 Nov 2017 03:19:10 GMThttp://ir.ynao.ac.cn:80/handle/114a53/101762017-11-09T03:19:10Z