Updated Toulouse solar models including the diffusion-circulation coupling and the effect of μ-gradients

New solar models are presented, which have been computed with the most recent physical inputs (nuclear reaction rates, equation of state, opacities, microscopic diffusion). Rotation-induced mixing has been introduced in a way which includes the feed-back effect of the μ-gradient induced by helium settling. A parametrization of the tachocline region below the convective zone has also been added in the computations. The sound velocities have been computed in the models and compared to the seismic Sun. Our best model is described in some detail. Besides the new physical inputs, the most important improvement concerns the computations of μ-gradients during the solar evolution and their influence in slowing down rotation-induced mixing. This process can explain why lithium is depleted in the present Sun while beryllium is not, and meanwhile why ³He has not increased at the solar surface for at least 3 Gyrs.     

Laboratory absorption strengths and line shape parameters in the 4-0, 5-0, and 6-0 vibration bands of HD

Uncertainties in the fundamental line profiles and absorption strengths in HD are among the most important sources of error in the analysis of the spectra of HD in the atmosphere of the outer planets. Measurements of the 4-0, 5-0, and 6-0 vibrational bands of HD, taken at room temperature and a range of densities from 0.3 to 1.7 amagat are reported. High S/N spectra have been obtained at a spectral resolution finer than the natural line widths, allowing analysis of spectral profiles, absorption strengths, and pressure shifts in the HD lines. Line profiles are interpreted in terms of the theoretical Galatry approximation, and the HD pressure-broadening and self-diffusion coefficients are determined as free parameters.     

Understanding the spectral energy distributions of the galactic star forming regions IRAS 18314-0720, 18355-0532 and 18316-0602

Embedded Young Stellar Objects (YSO) in dense interstellar clouds are treated self-consistently to understand their spectral energy distributions (SED). Radiative transfer calculations in spherical geometry involving the dust as well as the gas component, have been carried out to explain observations covering a wide spectral range encompassing near-infrared to radio continuum wavelengths. Various geometric and physical details of the YSOs are determined from this modelling scheme. In order to assess the effectiveness of this self-consistent scheme, three young Galactic star forming regions associated with IRAS 18314-0720, 18355-0532 and 18316-0602 have been modelled as test cases. They cover a large range of luminosity (≈ 40). The modelling of their SEDs has led to information about various details of these sources, e.g. embedded energy source, cloud structure and size, density distribution, composition and abundance of dust grains etc. In all three cases, the best fit model corresponds to the uniform density distribution. Two types of dust have been considered, viz., Draine & Lee (DL) and the Mezger, Mathis & Panagia (MMP). Models with MMP type dust explain the dust continuum and radio continuum emission from IRAS 18314-0720 and 18355-0532 self-consistently. These models predict much lower intensities for the fine structure lines of ionized heavy elements, than those observed for IRAS 18314-0720 and 18355-0532. This discrepancy has been resolved by invoking clumpiness in the interstellar medium. For IRAS 18316-0602, the model with DL type dust grains is preferred.     

Spatially resolved methane band photometry of Saturn: I. Absolute reflectivity and center-to-limb variations in the 6190-, 7250-, and 8900-Å bands

We present spatially resolved measurements of Saturn's absolute reflectivity in methane bands at 6190, 7250, and 8900 Å and in nearby continuum regions. Images were obtained through narrow-band interference filters with a 500 × 500-pixel charge-coupled device. Band/continuum ratios were measured to high accuracy by referencing to the ring brightness in each image. Several data processing techniques enhanced the quality of the observations. These are the use of the ring symmetry to find center position and orientation, accurate subtraction of ring light, and constrained image deconvolution. Uncertainty in the continuum absolute reflectivity is ±10%. Uncertainties in band/continuum ratios are from one to several percent. The Equatorial Zone was much brighter than any other latitude in the strong 8900 band image. Northern mid-latitudes were brighter than southern mid-latitudes. The latter observation indicates fewer high-altitude aerosols in the south, a possible result of atmospheric dynamics or seasonal sublimation of NH₃ crystals. The data are tabulated and presented in a form suitable for quantitative scattering model analyses.     

Variability and possible rapid evolution of the hot post-AGB stars Hen 3-1347, Hen 3-1428, and LSS 4634

We present the results of spectroscopic and photometric observations for three hot southern-hemisphere post-AGB objects, Hen 3-1347 = IRAS 17074-1845, Hen 3-1428 = IRAS 17311-4924, and LSS 4634 = IRAS 18023-3409. In the spectrograms taken with the 1.9-m telescope of the South African Astronomical Observatory (SAAO) in 2012, we have measured the equivalent widths of the most prominent spectral lines. Comparison of the new data with those published previously points to a change in the spectra of Hen 3-1428 and LSS 4634 in the last 20 years. Based on ASAS data, we have detected rapid photometric variability in all three stars with an amplitude up to 0 _· ^m 3-0 _· ^m 4 in the V band. A similarity between the patterns of variability for the sample stars and other hot protoplanetary nebulae is pointed out. We present the results of UBV observations for Hen 3-1347, according to which the star undergoes rapid irregular brightness variations with maximum amplitudes ΔV = 0 _· ^m 25, ΔB = 0 _· ^m 25, and ΔU = 0 _· ^m 30 and shows color-magnitude correlations. Based on archival data, we have traced the photometric history of the stars over more than 100 years. Hen 3-1347 and LSS 4634 have exhibited a significant fading on a long time scale. The revealed brightness and spectrum variations in the stars, along with evidence for their enhanced mass, may be indicative of their rapid post-AGB evolution.     

射电源0420—014,1334—127和2345—167中的视超光速运动

本文叙述南天区 5GHzVLBI普查中新发现的视超光速射电源 ,0 4 2 0— 0 1 4,1 334—1 2 7和 2 345— 1 67,这些结果尚待进一步的观测加以证实     

Structure of the Clusters of Galaxies A 2634, A 1983, and DC 0428-53

The hierarchical and dynamical structure of three clusters of galaxies, A 2634, A 1983, and DC 0428-53, is investigated. Based on their example, we can say that the central cD galaxies play the leading role in clusters, affecting the course of their evolution. Radio and x-ray galaxies are not always part of the substructure. The morphological composition of various hierarchical subgroups depends on the stage of evolution. Clusters have a tendency to be oriented in the direction toward the nearest neighbor.