Spectrum of the Extreme Ultraviolet Nightglow as Measured by EURD

After 2 years of operation onboard the Spanish satellite MINISAT, EURDhas achieved an unprecedented success in the observation of the terrestrialnightglow in the EUV, covering a range of 350-1100 Å EURD hasprovided a total of more than 543 hours ofintegration in the long wavelength spectrometer and more than898 hours in the short wavelength one, allowing the achievement of the most detailed atlas of the terrestrial EUV nightglow ever obtained. We present here the spectra obtained, together with the identification of the lines, some of themdetected for the first time in the nightglow. These spectrarepresent an improvement in sensitivity of several orders of magnitude with respect to previous observations. It has beenpossible, for the first time, to identify the complete Lymanseries of atomic hydrogen, resolving up to Lyman-. It hasalso been possible to identify the helium Lyman- line at 537 Å andto detect other lines of the blended Lyman series of helium, at 515 and522 Å. The spectra clearly show the presenceof the OII lines at 617, 644, 673, and 718 Å, previouslyobserved in the dayglow but seen here for the first time in thenightglow. In addition to the recombination continuum of the atomicoxygen at 911 Å, two features of OI have been detected in thenightglow: the 3s ³D_o transition at 989 Å, previouslyobserved by Chakrabarti (1984) and the 2p³4s³S^o transition at 1040 Å, partially overlapped with Lyman , but clearly distinguishable from it. This feature has been seen for the first timein the terrestrial nightglow. The radiative recombination continuum of atomic oxygen at 911 Å, that wasabsent in the observations of the first year of operation of EURD,is now clearly visible. The reasons of the absence of the OIfeature during the first year of operation are still unknown.Anderson et al. (1976) also noticed a strong variation with time of this 911 Å emission.     

Evidence of Evolution in the Dense Cores in Massive Star Forming Regions

The excitation of H2O masers usually needs very high density gas, hence it can serve as a marker of dense gas in HII region. We selected a sample of H2O maser sources from Plume et al. (four with, and four without detected CS(J = 7-6) emission), and observed them in 13CO(J=1-0) and C18O (J=1-0). C18O (J=1-0) emission was detected only in three of the sources with detected CS(J=7-6) emission. An analysis combined with some data in the literature suggests that these dense cores may be located at different evolutionary stages. Multi-line observation study may provide us clues on the evolution of massive star forming regions and the massive stars themselves.     

Comparative Analyses of Brookhaven National Laboratory Nuclear Decay Measurements and Super-Kamiokande Solar Neutrino Measurements: Neutrinos and Neutrino-Induced Beta-Decays as Probes of the Deep Solar Interior

An experiment carried out at the Brookhaven National Laboratory over a period of almost 8 years acquired 364 measurements of the beta-decay rates of a sample of \({}^{32}\mbox{Si}\) and, for comparison, of a sample of \({}^{36}\mbox{Cl}\). The experimenters reported finding “small periodic annual deviations of the data points from an exponential decay?…?of uncertain origin”. We find that power-spectrum and spectrogram analyses of these datasets show evidence not only of the annual oscillations, but also of transient oscillations with frequencies near 11 year^?1 and 12.5 year^?1. Similar analyses of 358 measurements of the solar neutrino flux acquired by the Super-Kamiokande neutrino observatory over a period of about 5 years yield evidence of an oscillation near 12.5 year^?1 and another near 9.5 year^?1. An oscillation near 12.5 year^?1 is compatible with the influence of rotation of the radiative zone. We suggest that an oscillation near 9.5 year^?1 may be indicative of rotation of the solar core, and that an oscillation near 11 year^?1 may have its origin in a tachocline between the core and the radiative zone. Modulation of the solar neutrino flux may be attributed to an influence of the Sun’s internal magnetic field by the Resonant Spin Flavor Precession (RSFP) mechanism, suggesting that neutrinos and neutrino-induced beta decays can provide information about the deep solar interior.     

海量巡天数据在线可视化技术综述

海量巡天数据在线可视化是多波段数据融合的应用之一,对大数据时代天文科研工作和科学普及具有重要意义。近年来,国外出现越来越多类似谷歌地图等互联网地图的天图在线可视化系统。为解决拼接生成的大巡天数据文件所导致的在线加载显示缓慢的问题,天文界普遍采用瓦片地图技术。该技术对数据进行分层保存,在浏览器端按需加载、分层显示。HiPS(hierarchicalprogressive survey)和TOAST(tessellated octahedral adaptive subdivision transform)等分层可视化技术以及一些巡天数据拼接和瓦片生成工具,如Hipsgen.jar和Montage等,目前已应用于Aladin Lite,ESASky,WWT(WorldWide Telescope)等在线可视化系统的开发。海量巡天数据在线可视化也遇到一些需要解决的问题,如数据分层导致了数据量的再次增加,巡天图像拼接耗时较长,多信使数据融合显示等。综述了分层可视化技术、瓦片地图金字塔的创建等内容,并对几款主流的在线可视化系统进行了对比分析,讨论了在线可视化遇到的问题及发展方向。     

五维Bianchi-Ⅴ型宇宙模型的辐射解

本文给出了理想流体五维Bianchi-V型的宇宙模型的严格解,并讨论了解的奇性,发现该解随着时间的增长将趋于五维膨胀各向同性宇宙模型。     

Possible Evidence of Time Variation of Weak Interaction Constant from Double Beta Decay Experiments

A comparison is made of the probability of the process of two neutrino double beta decay for ⁸²Se in direct (counter) and geochemical experiments. It is shown that the probability is systematically lower in geochemical experiments, which characterize the probability of ββ(2ν) decay a few billion years ago. The experimental data for ¹³⁰Te are also analyzed. It is shown that geochemical measurements on young minerals give lower values of T _1/2 (¹³⁰Te) and T _1/2 (⁸²Se) as compared to measurements on old minerals. It is proposed that this could be due to a change in the weak interaction constant with time. Possibilities of new, precise measurements performed with the aid of counters and geochemical experiments are discussed. This revised version was published online in July 2006 with corrections to the Cover Date.     

Imaging the Earth’s Interior: the Angular Distribution of Terrestrial Neutrinos

Decays of radionuclides throughout the earth’s interior produce geothermal heat, but also are a source of antineutrinos; these geoneutrinos are now becoming observable in experiments such as KamLAND. The (angle-integrated) geoneutrino flux has been shown to provide a unique probe of geothermal heating due to decays, and an integral constraint on the distribution of radionuclides in the earth. In this paper, we calculate the angular distribution of geoneutrinos, which opens a window on the differential radial distribution of terrestrial radionuclides. We develop the general formalism for the neutrino angular distribution. We also present the inverse transformation which recovers the terrestrial radioisotope distribution given a measurement of the neutrino angular distribution. Thus, geoneutrinos not only allow a means to image the earth’s interior, but offer a direct measure of the radioactive earth, both revealing the earth’s inner structure as probed by radionuclides, and allowing a complete determination of the radioactive heat generation as a function of radius. Turning to specific models, we emphasize the very useful approximation in which the earth is modeled as a series of shells of uniform density. Using this multishell approximation, we present the geoneutrino angular distribution for the favored earth model which has been used to calculate the geoneutrino flux. In this model the neutrino generation is dominated by decays of potassium, uranium, and thorium in the earth’s mantle and crust; this leads to a very “peripheral” angular distribution, in which 2/3 of the neutrinos come from angles θ ≳ 60° away from the nadir. We note that a measurement of the neutrino intensity in peripheral directions leads to a strong lower limit to the central intensity. We briefly discuss the challenges facing experiments to measure the geoneutrino angular distribution. Currently available techniques using inverse beta decay of protons require a (for now) unfeasibly large number of events to recover with confidence the forward scattering signal from the background of subsequent elastic scatterings. Nevertheless, it is our hope that future large experiments, and/or more sensitive techniques, can resolve an image of the earth’s radioactive interior.     

Evidence for a Strong Correlation of Solar Proton Events with Solar Radio Bursts

A statistical analysis is made on the correlation between solar proton events with energies >10Mev and solar radio bursts during the four-year period from 1997 November to 2000 November. We examine 28 solar proton events and their corresponding solar radio bursts at 15400, 8800, 4995, 2695, 1415, 606, 410 and 245 MHz. The statistical result shows that there is a close association between solar proton events and ≥3 solar radio bursts occurring at several frequencies, one or two days before. In particular, it is noteworthy that proton events occurring     

Calculating Method and Characteristics of the Distribution of Neutron Exposures in the Radiative S-process Nucleosynthesis Model for AGB Stars

A study on the distribution of neutron exposures in a low-mass asymptotic giant branch (AGB) star is presented, according to the s-process nucleosynthesis model with the ¹²C(α, n)¹⁶O reaction occurred under radiative conditions in the interpulse phases. The model parameters, such as the over- lap factor r of two successive convective thermal pulses, the mass ratio q of the ¹³C shell with respect to the He intershell, and the effective mass of ¹³C in the ¹³C shell, vary with the pulse number. Considering these factors, a calculating method for the distribution of neutron exposures in the He intershell has been presented. This method has the features of simplicity and universality. Using this method, the exposure distribution for the stellar model of a star with the mass of 3 M_? and the solar metallicity has been calculated. The results suggest that under the reasonable assumption that the number density of neutrons is uniform in the ¹³C shell, the ?nal exposure distribution approaches to an exponential distribution. For a stellar model with the de?nite initial mass and metallicity, there is a de?nite relation between the mean neutron exposure τ₀ and the neutron exposure Δτ of each pulse, namely τ₀ = 0.434λ(q1, q2, …, qm_max +1, …, r₁, r₂, …, rm_max +1)Δτ, where m_max is the total number of thermal pulses with the third dredge-up episode, and the proportional coeffcient λ(q₁, q₂, …, qm_max +1, …, r₁, r₂, …, rm_max +1) can be determined by an exponential curve ?tting to the ?nal exposure distribution. This new formula quantitatively uni?es the classical model with the s-process nu- cleosynthesis model by means of neutron exposure distribution, and makes the classical model continue to offer guidance and constraints to the s-process nu- merical calculations of stellar models.     

AGB星辐射s-过程核合成模型中子辐照量分布的计算方法和特点

考虑到模型参量随脉冲数的变化,推导出13C辐射燃烧的低质量AGB星s-过程核合成模型中子辐照量分布的计算方法,该方法具有普适性和简洁性.利用该方法,计算了3 M☉、太阳金属丰度恒星模型的中子辐照量分布.结果表明,若合理假设13C薄层内中子数密度均匀分布,则辐射核合成模型最终的中子辐照量分布趋近于指数分布.对于初始质量一定、金属丰度一定的恒星模型,平均中子辐照量τ0与每个脉冲的中子辐照量△τ存在确定的关系:τ0=0.434λ(q1,q2…qmmax+1,r1,r2…rmmax+1)△τ,式中mmax是带挖掘的脉冲总数,比例系数λ(q1,q2…qmmax+1,r1,r2…rmmax+1)可通过对最终中子辐照量分布的指数拟合得到.该式从中子辐照量分布角度定量地将经典模型和辐射s-过程核合成模型统一起来,使经典模型能为恒星模型核合成数值计算提供指导和约束.     

A Time-Dependent Model of Radiative and Conductive Thermal Energy Transport in Planetary Regoliths with Applications to the Moon and Mercury

Modeling thermal energy transfer in planetary regoliths involves treating four processes: visible radiative transfer, thermal radiative transfer, conductive transfer, and heat storage. We explicitly treat these processes while considering time-dependent problems, and we apply this model to the regoliths of the Moon and Mercury. Fitting the model to observational data allows us to constrain the radiative resistivity and thermal inertia parameters of these regoliths and hence constrain their conductivities, thermal extinction coefficients, and average grain sizes. It is also found that water ice would be stable in the polar subsurfaces of both bodies, even in areas which receive sunlight during the day.     

Radiative constraints on the energy budget of the tropical atmosphere

A simple one-dimensional model is presented to describe the energy budget of the tropical atmosphere. Heating of the atmosphere is associated primarily with latent energy released due to precipitation in localized regions of intense cumulonimbus activity. Air transported to upper regions of the troposphere by cumulonimbus systems is returned to the surface over a large region of descent. Heat released by subsidence is balanced primarily by emission of radiation in the infrared. The model accounts for this energy balance, exploring specifically the constraints on permissible fluxes of mass and energy.

Results suggest that the strength of the background subsidence field in the tropics may be sensitive to surface temperature and to changes in atmospheric composition, specifically variations in the altitude distribution of H₂O and changes in the abundance of greenhouse gases such as CO₂. The mean level of detrainment of deep cumulonimbus clouds is found to increase with increasing surface temperature. This behavior is shown to be sensitive to atmospheric composition. The surface temperature for an atmosphere containing twice the present level of CO₂ is predicted to increase by 1.4K, about 25% less than the change obtained with models in which the lapse rate of temperature is specified at lower altitudes, where assumptions of radiative equilibrium would lead otherwise to a statically unstable condition.

Buoyancy considerations suggest that there may be an upper limit to the range of permissible values for surface temperature in the tropics. Models in which the subsidence mass flux is assumed constant with respect to altitude are found to be unable to maintain buoyancy for rising air in the face of heat released by descent when surface temperatures exceed about 312K.     

Additional Evidence Supporting a Model of Shallow,High-Speed Supergranulation

Recently, Duvall and Hanasoge (Solar Phys. 287, 71, 2013) found that large-distance separation [Δ] travel-time differences from a center to an annulus [δt _oi] implied a model of the average supergranular cell that has a peak upflow of 240 m?s^?1 at a depth of 2.3 Mm and a corresponding peak outward horizontal flow of 700 m?s^?1 at a depth of 1.6 Mm. In the present work, this effect is further studied by measuring and modeling center-to-quadrant travel-time differences [δt _qu], which roughly agree with this model. Simulations are analyzed that show that such a model flow would lead to the expected travel-time differences. As a check for possible systematic errors, the center-to-annulus travel-time differences [δt _oi] are found not to vary with heliocentric angle. A consistency check finds an increase of δt _oi with the temporal frequency [ν] by a factor of two, which is not predicted by the ray theory.     

The Data Depth-weight-kernel Estimation of the Model Error of Satellite Orbit Determination

It is an objective fact that there exists error in the satellite dynamic model and it will be transferred to satellite orbit determination algorithm, forming a part of the connotative model error. Mixed with the systematic error and random error of the measurements, they form the unitive model error and badly restrict the precision of the orbit determination. We deduce in detail the equations of orbit improvement for a system with dynamic model error, construct the parametric model for the explicit part of the model and nonparametric model for the error that can not be explicitly described. We also construct the partially linear orbit determination model, estimate and fit the model error using a two-stage estimation and a kernel function estimation, and finally make the corresponding compensation in the orbit determination. Beginning from the data depth theory, a data depth weight kernel estimator for model error is proposed for the sake of promoting the steadiness of model error estimation. Simulation experiments of SBSS are performed. The results show clearly that the model error is one of the most important effects that will influence the precision of the orbit determination. The kernel function method can effectively estimate the model error, with the window width as a major restrict parameter. A data depth-weight-kernel estimation, however, can improve largely the robustness of the kernel function and therefore improve the precision of orbit determination.     

A Check on the Cardassian Expansion Model with Type－IaSupernovae Data

We use the magnitude-redshift relation for the type Ia supernova datacompiled by Riess et al. to analyze the Cardassian expansion scenario. This sce-nario assumes the universe to be flat, matter dominated, and accelerating, but contains no vacuum contribution.The best fitting model parameters are H0=65.3kms^-1 Mpc^-1, n= 0.35 and Ω= 0.05. When the highest redshift supernova,SN 1997ck, is excluded, H0 remains the same, but n becomes 0.20 and Ωm, 0.15, and the matter density remains unreasonably low. Our result shows that this particular scenario is strongly disfavoured by the SNeIa data.     

Decay of the vacuum energy into cosmic microwave background photons

We examine the possibility of the decay of the vacuum energy into a homogeneous distribution of a thermalized cosmic microwave background (CMB), which is characteristic of an adiabatic vacuum energy decay into photons. It is shown that observations of the primordial density fluctuation spectrum, obtained from CMB and galaxy distribution data, restrict the possible decay rate. When photon creation due to an adiabatic vacuum energy decay takes place, the standard linear temperature dependence   T ( z ) = T ₀(1 + z )  is modified, where T ₀ is the present CMB temperature, and can be parametrized by a modified CMB temperature dependence     . From the observed CMB and galaxy distribution data, a strong limit on the maximum value of the decay rate is obtained by placing a maximum value  β_max≃ 3.4 × 10⁻³  on the β parameter.     

The Effect of Radiative Efficiency on the Growth of the Black Hole Mass

The effect of variation of radiative efficiency on the growth of the black hole mass is discussed. In the process of accretion, the black hole's angular momentum varies, resulting in a variation of the radiative efficiency, and the growth of the black hole mass is thereby affected. For the exponential growth model of back holes and taking into account the effect of a varying radiative efficiency, the equation for the growth of the black hole mass is solved numerically. Compared to the model that assumes a constant radiative efficiency, the result indicates that variation of radiative efficiency has a marked, retarding effect on the growth of the black hole mass. This model can explain quantitatively some recent observational results.     

Mathematical Model of the Motion of Gaseous Thermal Decomposition Products of Composites in a Porous Frame under Strong Heat Flows

Solar System Research - The paper describes theoretical issues of the motion of gaseous thermal decomposition products of composite materials in a porous frame structure under the effect of...     

Radiative transitions of the helium atom in highly magnetized neutron star atmospheres

Recent observations of thermally emitting isolated neutron stars revealed spectral features that could be interpreted as radiative transitions of He in a magnetized neutron star atmosphere. We present Hartree–Fock calculations of the polarization-dependent photoionization cross-sections of the He atom in strong magnetic fields ranging from 10¹² to 10¹⁴ G. Convenient fitting formulae for the cross-sections are given along with the related oscillator strengths for various bound–bound transitions. The effects of finite nucleus mass on the radiative absorption cross-sections are examined using perturbation theory.     

Power Spectrum Analysis of Physikalisch-Technische Bundesanstalt Decay-Rate Data: Evidence for Solar Rotational Modulation

Evidence for an anomalous annual periodicity in certain nuclear-decay data has led to speculation on a possible solar influence on nuclear processes. We have recently analyzed data concerning the decay rates of ³⁶Cl and ³²Si, acquired at the Brookhaven National Laboratory (BNL), to search for evidence that might be indicative of a process involving solar rotation. Smoothing of the power spectrum by weighted-running-mean analysis leads to a significant peak at frequency 11.18 year⁻¹, which is lower than the equatorial synodic rotation rates of the convection and radiative zones. This article concerns measurements of the decay rates of ²²⁶Ra acquired at the Physikalisch-Technische Bundesanstalt (PTB) in Germany. We find that a similar (but not identical) analysis yields a significant peak in the PTB dataset at frequency 11.21 year⁻¹, and a peak in the BNL dataset at 11.25 year⁻¹. The change in the BNL result is not significant, since the uncertainties in the BNL and PTB analyses are estimated to be 0.13 year⁻¹ and 0.07 year⁻¹, respectively. Combining the two running means by forming the joint power statistic leads to a highly significant peak at frequency 11.23 year⁻¹. We will briefly comment on the possible implications of these results for solar physics and for particle physics.