Atoms

An empirical model of the TU Muscae binary star system has been developed by a study of 23 high resolution SWP spectrophotometric images that were obtained with the International Ultraviolet Explorer (IUE) satellite telescope including some that were downloaded from the NASA/MAST IUE Archive. The images are well distributed in Keplerian orbital phase thereby permitting a simultaneous fitting of the C IV wind-line profile by the SEI method and the light curve for the blanketed continuum (1450–1490 Å) bandpass by means of a program developed by the author. The result is a set of parameters characterizing the physical and geometric properties of the wind envelopes surrounding the stars. Surprisingly, there is no evidence for a P Cygni profile or strong, distinguishable shock front in the system, as has been found for similar investigations of EM Carinae and HD 159176. This is probably a result of the contact nature of the binary and the high-temperature environment of such a shock. That is, most of the carbon ions in the shock are more highly ionized. Based on the parameters for the SEI fit to the C IV profile, the value for the ionization fraction of C IV in the wind was calculated to be 10⁻⁴. With this value, the mass loss rate, Ṁ, calculated from two independent equations, was found to be about 10⁻⁶ solar masses per year (M_ʘ/yr). The UV line blanketing in the 1500 to 1600 Ångstrom bandpass was found to be erratically variable with orbital phase and time, indicating a variable amount of fast moving, dense clouds in the winds and/or a great amount of turbulence. The meaning of rotational velocities for the stars is problematic and depends on what point on the photospheres one is considering.

The Atomic Lunar Seismometer (ALS) is an atom-interferometer instrument concept for measuring the lunar gravity and vibration modes at long time scales. Compared to other seismometer techniques, atom interferometers offer a pathway toward an ultra-low drift seismometer for signals around and below the mHz frequency range. The ALS instrument concept is also applicable to other terrestrial bodies such as Mars. In this paper, we present our instrument design based on a 5 cm tall atomic fountain and summarize the test results obtained in a laboratory environment. This development is specifically to optimize and accommodate in lunar environment. Presently, the instrument’s short-term sensitivity is 1.4 × 10⁻⁶ m/s²/$\sqrt{\mathrm{Hz}}$ (140 $\mathsf{\mu }$Gal/$\sqrt{\mathrm{Hz}}$), limited by the vibration noise in our lab, and it averages down to 6.7 × 10⁻⁸ m/s² (6.7 $\mathsf{\mu }$Gal) after 445 s.

Accurate atomic data for heavy ions are required for spectroscopic diagnostics and impurity transport modeling in magnetic-confinement fusion devices, particularly for tungsten and its neutron-induced transmutation products. In the present work, we investigate the ytterbium-like ions Ta IV, W V, Re VI, Os VII, Ir VIII, and Pt IX using complementary pseudo-relativistic Hartree–Fock (HFR) and fully relativistic multiconfiguration Dirac–Hartree–Fock (MCDHF) approaches. Semi-empirical calculations were first performed using the HFR method including core polarization corrections (HFR+CPOL). The evolution of correlation effects along the isoelectronic sequence was then analyzed through an alternative HFR(CV) model in which the most important core-excited configurations were introduced explicitly to account for core–valence interactions. Extensive least-squares fits to the available experimental energy levels were carried out for all ions considered. The results reveal that the HFR+CPOL approach provides an adequate description of Ta IV and W V, while explicit treatment of core–valence correlations becomes increasingly important from Re VI onwards owing to the growing interaction between the 5d5f and 5p⁵5d³ configurations. New energy level classifications, level compositions, oscillator strengths, and transition probabilities are reported and critically assessed through comparisons between HFR and MCDHF calculations. The resulting dataset extends previous investigations of rhenium and osmium ions and provides benchmark atomic data for heavy-ion spectroscopy and future fusion-plasma applications.