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Ram pressure stripping (RPS) is a process that removes the interstellar medium (ISM) quickly, playing a vital role in galaxy evolution. Previous RPS studies have treated the ISM as single-phase or lack the resolution and physical processes to properly capture the full multiphase ISM. To improve this simplification, we introduce an inflowing, hot intracluster medium (ICM) into a self-consistently modeled ISM in a local patch of star-forming galactic disks using the TIGRESS framework. Our simulations reveal that the workings of RPS are not only direct acceleration of the ISM by ICM ram pressure but also mixing-driven momentum transfer involving significant phase transition and radiative cooling. The hot ICM passes through the low-density channels of the porous, multiphase ISM; shreds the cool ISM; and creates mixing layers. The ICM momentum is transferred through the mixing layers while populating the intermediate-temperature gas and radiating thermal energy away. The mixed gas extends beyond galactic disks and forms stripped tails that cool back unless the ICM fluxes are large enough to prevent cooling until they escape the simulation domain. The mixing-driven momentum transfer predicts that the more ICM mixes in, the faster the ISM moves, resulting in the anticorrelation of outflow velocity and gas metallicity of the stripped ISM. The compression of the ISM disks due to the ICM ram pressure enhances star formation rates up to 50% compared to the model without ICM. With the ICM ram pressure higher than the disk anchoring pressure, star formation is quenched within ∼100 Myr. [ABSTRACT FROM AUTHOR]

Results of experimental and theoretical investigations into the electron-impact excitation of the resonance 6 s 6 p 1 P 1 ° â†' 6 s 21 S 0 (132.2 nm), as well as the cascade 6 s 7 s 1 S 0 â†' 6 s 6 p 1 P 1 ° (309.2 nm) and 6 p 21 D 2 â†' 6 s 6 p 1 P 1 ° (150.8 nm) spectral transitions from the ground 6 s 21 S 0 level in the thallium ion, are presented. Crossed beams of electrons and Tl+ ions in combination with a spectroscopic method were used in the experiment. Measured cross sections have a distinct resonance structure arising mainly from the electron decay of atomic 5 d 96 s 26 p 2, 5 d 106 s 7 s (1 S) np (n â©ľ 7), 5 d 106 s 6 d (1 D) np (n â©ľ 6), 5 d 106 s 6 d (1 D) nd (n â©ľ 6) and ionic 5 d 96 s 2 np, 5 d 96 s 2 nd, 5 d 96 snp (n â©ľ 6) autoionizing levels, as well as radiative transitions from the higher 6 s 7 s 1 S 0, 6 s 6 d 1 D 2, and 6 p 21 D 2, 1 S 0 ionic levels. Relativistic distorted wave (RDW) calculations are performed to obtain the effective cross sections for the above transitions. The absolute values of the cross sections are found to be 1.39 Ă— 10âˆ'16 cm2 at 300 eV for the λ 132.2 nm resonance line, and 0.11 Ă— 10âˆ'16 cm2 and 0.56 Ă— 10âˆ'16 cm2 at 100 eV for the λ 309.2 nm and λ 150.8 nm lines, respectively. The contribution of the cascade transitions being studied to the effective cross section of the λ 132.2 nm resonance line at the energy of 100 eV is about 30%. A calculation using the semi-empirical Van Regemorter formula is also performed to obtain the effective cross section of the resonance λ 132.2 nm line. The absolute value of the cross section at 300 eV is found to be nearly the same as that given by the RDW calculation. [ABSTRACT FROM AUTHOR]

Binary neutron star (NS) mergers have been expected to synthesize r-process elements and emit radioactively powered radiation, called kilonovae. Although r-process nucleosynthesis was confirmed by the observations of GW170817/AT2017gfo, no trace of individual elements has been identified except for strontium. In this paper, we perform systematic calculations of line strength for bound–bound transitions and radiative transfer simulations in NS merger ejecta toward element identification in kilonova spectra. We find that Sr ii triplet lines appear in the spectrum of a lanthanide-poor model, which is consistent with the absorption feature observed in GW170817/AT2017gfo. The synthetic spectrum also shows the strong Ca ii triplet lines. This is natural because Ca and Sr are coproduced in the material with relatively high electron fraction and their ions have similar atomic structures with only one s-electron in the outermost shell. The line strength, however, highly depends on the abundance distribution and temperature in the ejecta. For our lanthanide-rich model, the spectra show the features of doubly ionized heavy elements, such as Ce, Tb, and Th. Our results suggest that the line-forming region of GW170817/AT2017gfo was lanthanide-poor. We show that the Sr ii and Ca ii lines can be used as a probe of physical conditions in NS merger ejecta. Absence of the Ca ii line features in GW170817/AT2017gfo implies that the Ca/Sr ratio is <0.002 in mass fraction, which is consistent with nucleosynthesis for electron fraction ≥0.40 and entropy per nucleon (in units of Boltzmann constant) ≥25. [ABSTRACT FROM AUTHOR]

Thermal corrections to the one-photon spontaneous and induced transition probabilities for hydrogen and hydrogen-like ions are evaluated. The found thermal corrections are given by the vertex Feynman graph, where the vertex represents the thermal interaction between the bound electron and the nucleus. All derivations of thermal corrections to bound–bound transitions for an atom exposed to blackbody radiation are made in a fully relativistic approach within the framework of the adiabatic S-matrix formalism. It is found that the vertex-type radiative corrections to the transition rates can be at the level of a few percent to corresponding spontaneous rates for highly excited states in the hydrogen atom. A comprehensive analysis of the vertex-type thermal corrections for hydrogen-like atomic systems is presented. [ABSTRACT FROM AUTHOR]

With the recent advent of circular polarization capabilities at the Atacama Large Millimeter/submillimeter Array (ALMA), Zeeman effect measurements of spectral lines are now possible as a means to directly probe line-of-sight magnetic fields in protoplanetary disks (PPDs). We present a modeling study that aims to guide physical interpretation of these anticipated observations. Using a fiducial density structure based on a typical ringed disk, we simulate line emission for the hyperfine components of the CN J = 1−0 transition with the POLARIS radiative transfer code. Since the expected magnetic field and typical CN distribution in PPDs remain largely unconstrained, we produce models with several different configurations. Corresponding integrated Stokes I and V profiles and 0.4 km s−1 resolution, 1″ beam convolved channel maps are presented. We demonstrate that the emission signatures from toroidally dominated magnetic fields are distinguishable from vertically dominated magnetic field based on channel map morphology. Due to line-of-sight and beam cancellation effects, disks with toroidal -field configurations result in significantly diminished Stokes V emission. Complex magnetic fields therefore render the traditionally used method for inferring line-of-sight magnetic field strengths (i.e., fitting the derivative of the Stokes I to the Stokes V profile) ambiguous, since a given intrinsic field strength can yield a variety of Stokes V amplitudes depending on the magnetic field geometry. In addition, gas gaps can create structure in the integrated Stokes V profile that might mimic magnetic substructure. This method should therefore be applied with caution in PPD environments and can only confidently be used as a measure of magnetic field strength if the disk's magnetic field configuration is well understood. [ABSTRACT FROM AUTHOR]

We model the (v′ = 1, v″ = 0) band of the Birge–Hopfield I band system of molecular nitrogen, N2, i.e. , emitted by nonthermal gas discharges in low pressure air. In particular, we calculate the rate of electron impact excitation of N2, which is thermally equilibrated at room temperature, to rotational levels J′ < 31 of N2(b1Πu, v′ = 1, J′). Subsequently, we calculate the intensity of emission lines resulting from radiative transitions from the aforementioned rotational levels to. Predissociation is the only nonradiative channel considered for the decay of N2(b1Πu, v′ = 1, J′) levels. [ABSTRACT FROM AUTHOR]

Si quantum dots (QDs) have a significant improvement in luminous efficiency compared with bulk Si, achieved by alleviating the forbiddance of no-phonon Γ–Γ radiative transition determined by the law of momentum conservation. Two divergent mechanisms have been proposed to account for the breakdown of momentum conservation in Si QDs, one is due to the space-confinement-induced spread of k -space wave functions associated with Heisenberg uncertainty principle Δr · Δk > 1/2, and the other is due to the interface-effect-induced intervalley mixing between indirect and direct bandgap states. Both mechanisms could cause a small overlap of the electron and hole wave functions in k -space and make vertical transitions allowed, which leads to the zero-phonon light emission. In this work, we unravel the hierarchical relationship between these two primary mechanisms in the process of zero-phonon light emission from indirect bandgap QDs, by performing semiempirical pseudopotential calculation including many-body interaction on the room-temperature luminescent properties of a series of Si, Ge, and Ge/Si core/shell QDs. We show that the space confinement mechanism is dominant in both Si and Ge indirect bandgap QDs, and the interface-induced intervalley coupling mechanism plays a minor role. While in Ge/Si core/shell QDs, the interface-induced intervalley coupling mechanism has a more pronounced contribution to enhanced light emission, implying one can further enhance light emission via engineering interface based on the intervalley coupling mechanism. Given this, we further engineer the Ge QD interface by bringing four motifs of Si/Ge multiple layers from previously inverse designed Si/Ge superlattices and core/shell nanowires for light emitters. We show that two out of four motifs always give rise to two orders of magnitude enhancement in light emission relative to the Ge and Si QDs. We demonstrate that the interface engineering can enhance light emission in indirect bandgap QDs substantially and regulate the intervalley coupling mechanism as the primary factor over the space confinement mechanism in breaking the momentum conservation law. [ABSTRACT FROM AUTHOR]

We model emissions from the Carroll-Yoshino (v′ = 0, v″ = 0) band of molecular nitrogen N2, i.e. due to nonthermal gas discharges in low pressure air and N2. In particular, we calculate the rate of excitation of thermally equilibriated N2 at room temperature (i.e. 300 K) to various rotational levels J′ of. Subsequently, we calculate the intensity of 47 emission lines resulting from radiative transitions from the aforementioned rotational levels. It is assumed that predissociation is the only nonradiative channel for the decay of excited levels. [ABSTRACT FROM AUTHOR]

State selective charge transfer cross sections are calculated in Mg12+ collisions with H and He atoms at incident energies of 1.0, 3.0, and 5.0 keV amu−1 using a time-dependent lattice method. Total capture cross sections using the time-dependent lattice method are found to be larger than those previously calculated using the Landau–Zener method. Lyman line ratios are calculated using the time-dependent lattice capture cross sections and standard radiative transitions for both the H and He atoms. Lyman line probabilities are presented for both H and He. The strongest probability for both H and He is the Lyman α emission, but relatively strong probabilities for He at an incident energy of 1.0 keV amu−1 are found for Lyman β, γ, δ, and ϵ emission. [ABSTRACT FROM AUTHOR]

Resonant enhancement of high harmonic generation can be obtained in plasmas containing ions with strong radiative transitions resonant with harmonic orders. The mechanism for this enhancement is still debated. We perform the first temporal characterization of the attosecond emission from a tin plasma under near-resonant conditions for two different resonance detunings. We show that the resonance considerably changes the relative phase of neighboring harmonics. For very small detunings, their phase locking may even be lost, evidencing strong phase distortions in the emission process and a modified attosecond structure. These features are well reproduced by our simulations, allowing their interpretation in terms of the phase of the recombination dipole moment. [ABSTRACT FROM AUTHOR]

By adopting a finite square-well potential, the analytic expressions of vorticity strengths, which are related to transverse currents, are derived for some selected E1 and E2 transitions. From these analytic expressions it can be seen clearly that, like the threshold strengths, the vorticity strengths are also sharply distributed just above the threshold in nuclei near the drip-line and mainly come from the orbits with small binding energy. [ABSTRACT FROM AUTHOR]

Weak interactions break time-reversal (T) symmetry in the two-state system of neutral K-mesons. We present and discuss a two-state mechanical system, i.e. a Foucault-type pendulum on a rotating table, for a full representation of K0&Kmacr;0 transitions by the pendulum motions including T violation. The pendulum moves with two different oscillation frequencies and two different magnetic dampings. Its equation of motion is identical to the differential equation for the real part of the CPT-symmetric K-meson wavefunction. The pendulum is able to represent microscopic CP and T violation with CPT symmetry owing to the macroscopic Coriolis force, which breaks the symmetry under reversal of motion. Video clips of the pendulum motions are given as supplementary material. [ABSTRACT FROM AUTHOR]

The CHIANTI spectral code consists of an atomic database and a suite of computer programs to calculate the optically thin spectrum of astrophysical objects and carry out spectroscopic plasma diagnostics. The database includes atomic energy levels, wavelengths, radiative transition probabilities, collision excitation rate coefficients, and ionization and recombination rate coefficients, as well as data to calculate free--free, free--bound, and two-photon continuum emission. Version 7 has been released, which includes several new ions, significant updates to existing ions, as well as Chianti-Py, the implementation of CHIANTI software in the Python programming language. All data and programs are freely available at http://www.chiantidatabase.org, while the Python interface to CHIANTI can be found at http://chiantipy.sourceforge.net. [ABSTRACT FROM AUTHOR]

Spectroscopy based on Stark broadening is a very efficient and successful method for diagnosing the physical conditions in laboratory or astrophysical plasmas. The studies are often focused on the lines of hydrogen or hydrogen-like ions due to the simple atomic structure. However, the Stark modeling may be difficult even for one-electron systems, in particular when radiative transitions with highly-degenerate Rydberg states are considered. Besides, the computations may become challenging for the modeling of line shapes in an optically thick plasma and accounting for non-local thermodynamical equilibrium (non-LTE) effects on the state populations. The statistical approach is a powerful technique which can be used to simplify complex coupled problems by replacing the numerous levels or lines by a single continuous distribution characterized by a reduced number of exact moments: area, center-of-gravity, variance, etc. In this paper, we study various statistical properties of a hydrogenic atom broadened by Stark effect. First, we derive the moments of level energies accounting for linear and quadratic Stark effects, electric-quadrupole and fine structure corrections. The resulting formulas allows one to estimate the relative importance of these corrections on the energies. We then derive the moments of the strength-weighted line energies for the Lyman and Balmer series in the framework of Linear-Stark effect. The moments are then used in a Gram–Charlier expansion series to represent the line shape, the resolution of the spectrum being controlled by the order at which the series is truncated. We show that the line shape of the transition can be expressed using universal functions of n and , independent of the atomic number and of the field intensity. This allows for fast Stark broadening calculations which can be used in more complex simulations (in opacity or emissivity codes, for radiative transfer simulations or non-LTE models). [ABSTRACT FROM AUTHOR]

We present lifetime measurements using beam-foil techniques for radiative transitions from the 3p4(1S)4s2S1/2, 3p4(3P)5 , and 3p4(3P)3d2F5/2 levels in Cl I and the corresponding results of the oscillator strengths for transitions at 1004.68, 1079.88, 1090.73, and 1094.77 Å, respectively. We compare our experimental results with available theoretical calculations and astronomical observations in an effort to resolve discrepancies among them. [ABSTRACT FROM AUTHOR]

By generalizing the theory of convection to any type of thermal and compositional source terms (diabatic processes), we show that thermohaline convection in Earth’s oceans, fingering convection in stellar atmospheres, and moist convection in Earth’s atmosphere are derived from the same general diabatic convective instability. We also show that “radiative convection” triggered by the CO/CH4 transition with radiative transfer in the atmospheres of brown dwarfs is analogous to moist and thermohaline convection. We derive a generalization of the mixing-length theory to include the effect of source terms in 1D codes. We show that CO/CH4 “radiative” convection could significantly reduce the temperature gradient in the atmospheres of brown dwarfs similarly to moist convection in Earth’s atmosphere, thus possibly explaining the reddening in brown dwarf spectra. By using idealized 2D hydrodynamic simulations in the Ledoux unstable regime, we show that compositional source terms can indeed provoke a reduction of the temperature gradient. The L/T transition could be explained by a bifurcation between the adiabatic and diabatic convective transports and seen as a giant cooling crisis: an analog of the boiling crisis in liquid/steam-water convective flows. This mechanism, with other chemical transitions, could be present in many giant and Earth-like exoplanets. The study of the impact of different parameters (effective temperature, compositional changes) on CO/CH4 radiative convection and the analogy with Earth moist and thermohaline convection is opening the possibility of using brown dwarfs to better understand some aspects of the physics at play in the climate of our own planet. [ABSTRACT FROM AUTHOR]

The Zombie Vortex Instability (ZVI) occurs in the dead zones of protoplanetary disks (PPDs), where perturbations excite baroclinic critical layers, generating “zombie” vortices and turbulence. In this work, we investigate ZVI with nonuniform vertical stratification; while ZVI is triggered in the stratified regions away from the midplane, the subsequent turbulence propagates into and fills the midplane. ZVI turbulence alters the background Keplerian shear flow, creating a steady-state zonal flow. Intermittency is observed, where the flow cycles through near-laminar phases of zonal flow punctuated by chaotic bursts of new vortices. ZVI persists in the presence of radiative damping, as long as the thermal relaxation timescale is more than a few orbital periods. We refute the premature claim by Lesur & Latter that radiative damping inhibits ZVI for disk radii . Their conclusions were based on unrealistically short cooling times using opacities with virtually no grain growth. We explore different grain growth and vertical settling scenarios, and find that the gas and dust in off-midplane regions are not necessarily in local thermodynamic equilibrium (LTE) with each other. In such cases, thermal relaxation timescales can be orders of magnitude longer than the LTE optically thin cooling times because of the finite time for energy to be exchanged between gas and dust grains via collisions. With minimal amounts of grain growth and dust settling, the off-midplane regions of disks are susceptible to ZVI, and much of the planet-forming regions can be filled with zombie vortices and turbulence. [ABSTRACT FROM AUTHOR]

We build a highly predictive 3-3-1 model, where the field content is extended by including several SU(3)L scalar singlets and six right handed Majorana neutrinos. In our model the gauge symmetry is supplemented by the discrete group, which allows to get a very good description of the low energy fermion flavor data. In the model under consideration, the discrete group is broken at very high energy scale down to the preserved Z2 discrete symmetry, thus generating the observed pattern of SM fermion masses and mixing angles and allowing the implementation of the loop level inverse seesaw mechanism for the generation of the light active neutrino masses, respectively. The obtained values for the physical observables in the quark sector agree with the experimental data, whereas those ones for the lepton sector also do, only for the case of inverted neutrino mass spectrum. The normal neutrino mass hierarchy scenario of the model is ruled out by the neutrino oscillation experimental data. We find an effective Majorana neutrino mass parameter of neutrinoless double beta decay of mee = 46.9 meV, a leptonic Dirac CP violating phase of −81.37° and a Jarlskog invariant of about 10−2 for the inverted neutrino mass hierarchy. The preserved Z2 symmetry allows for a stable scalar dark matter candidate. [ABSTRACT FROM AUTHOR]

This paper presents a detailed hydrostatic model of the upper atmosphere of HD 189733b, with the goal of constraining its temperature, particle densities, and radiation field over the pressure range 10–4 to 10 μbar, where the observed Hα transmission spectrum is produced. The atomic hydrogen level population is computed including both collisional and radiative transition rates. The Lyα resonant scattering is computed using a Monte Carlo simulation. The model transmission spectra are in broad agreement with the data. Excitation of the H(2ℓ) population is mainly by Lyα radiative excitation due to the large Lyα intensity. The density of H(2ℓ) is nearly flat over two decades in pressure and is optically thick to Hα. Additional models computed for a range of the stellar Lyman continuum (LyC) flux suggest that the variability in Hα transit depth may be due to the variability in the stellar LyC. Since metal lines provide the dominant cooling of this part of the atmosphere, the atmosphere structure is sensitive to the density of species such as Mg and Na, which may themselves be constrained by observations. Since the Hα and Na D lines have comparable absorption depths, we argue that the centers of the Na D lines are also formed in the atomic layer where the Hα line is formed. [ABSTRACT FROM AUTHOR]

Surges often appear as a result of the emergence of magnetized plasma from the solar interior. Traditionally, they are observed in chromospheric lines such as Hα 6563 and Ca ii 8542 . However, whether there is a response to the surge appearance and evolution in the Si iv lines or, in fact, in many other transition region lines has not been studied. In this paper, we analyze a simultaneous episode of an Hα surge and a Si iv burst that occurred on 2016 September 03 in active region AR 12585. To that end, we use coordinated observations from the Interface Region Imaging Spectrograph and the Swedish 1-m Solar Telescope. For the first time, we report emission of Si iv within the surge, finding profiles that are brighter and broader than the average. Furthermore, the brightest Si iv patches within the domain of the surge are located mainly near its footpoints. To understand the relation between the surges and the emission in transition region lines like Si iv, we have carried out 2.5D radiative MHD (RMHD) experiments of magnetic flux emergence episodes using the Bifrost code and including the nonequilibrium ionization of silicon. Through spectral synthesis, we explain several features of the observations. We show that the presence of Si iv emission patches within the surge, their location near the surge footpoints and various observed spectral features are a natural consequence of the emergence of magnetized plasma from the interior to the atmosphere and the ensuing reconnection processes. [ABSTRACT FROM AUTHOR]

In the era of large stellar spectroscopic surveys, there is an emphasis on deriving not only stellar abundances but also the ages for millions of stars. In the context of Galactic archeology, stellar ages provide a direct probe of the formation history of the Galaxy. We use the stellar evolution code MESA to compute models with atomic diffusion—with and without radiative acceleration—and extra mixing in the surface layers. The extra mixing consists of both density-dependent turbulent mixing and envelope overshoot mixing. Based on these models we argue that it is important to distinguish between initial, bulk abundances (parameters) and current, surface abundances (variables) in the analysis of individual stellar ages. In stars that maintain radiative regions on evolutionary timescales, atomic diffusion modifies the surface abundances. We show that when initial, bulk metallicity is equated with current, surface metallicity in isochrone age analysis, the resulting stellar ages can be systematically overestimated by up to 20%. The change of surface abundances with evolutionary phase also complicates chemical tagging, which is the concept that dispersed star clusters can be identified through unique, high-dimensional chemical signatures. Stars from the same cluster, but in different evolutionary phases, will show different surface abundances. We speculate that calibration of stellar models may allow us to estimate not only stellar ages but also initial abundances for individual stars. In the meantime, analyzing the chemical properties of stars in similar evolutionary phases is essential to minimize the effects of atomic diffusion in the context of chemical tagging. [ABSTRACT FROM AUTHOR]

Radiative emission during cold collisions between trapped laser-cooled Rb atoms and alkaline-earth ions (Ca+, Sr+, Ba+) and Yb+, and between Li and Yb+, are studied theoretically, using accurate effective core potential based quantum chemistry calculations of potential energy curves and transition dipole moments of the related molecular ions. Radiative association of molecular ions is predicted to occur for all systems with a cross section two to ten times larger than the radiative charge transfer one. Partial and total rate constants are also calculated and compared to available experiments. Narrow shape resonances are expected, which could be detectable at low temperature with an experimental resolution at the limit of the present standards. Vibrational distributions are also calculated, showing that the final molecular ions are not created in their ground state level. [ABSTRACT FROM AUTHOR]

Deformed quasiparticle random phase approximation with realistic nucleon–nucleon interactions is employed to investigate β-decay half-lives and β-delayed neutron emission probabilities of neutron-rich Kr and Sr isotopes. The residual particle–particle and particle-hole interactions are obtained in terms of the Brückner G-matrix with the charge-dependent Bonn nucleon–nucleon force. Both allowed Gamow–Teller and first-forbidden transitions are taken into account. The available experimental half-lives are well reproduced with a factor of about three. Predictions on β-decay properties are made for more neutron-rich isotopes, which could be useful for future experiments. [ABSTRACT FROM AUTHOR]

We examine the effect of different radiative transfer schemes on the properties of three-dimensional (3D) simulations of near-surface stellar convection in the superadiabatic layer, where energy transport transitions from fully convective to fully radiative. We employ two radiative transfer schemes that fundamentally differ in the way they cover the 3D domain. The first solver approximates domain coverage with moments, while the second solver samples the 3D domain with ray integrations. By comparing simulations that differ only in their respective radiative transfer methods, we are able to isolate the effect that radiative efficiency has on the structure of the superadiabatic layer. We find the simulations to be in good general agreement, but they show distinct differences in the thermal structure in the superadiabatic layer and atmosphere. [ABSTRACT FROM AUTHOR]

We have measured electron-ion recombination for C-like Mg6 + forming Mg5 +, and for B-like Mg7 + forming Mg6 +. These studies were performed using a merged electron-ion beam arrangement at the TSR heavy ion storage ring located in Heidelberg, Germany. Both primary ions have metastable levels with significant lifetimes. Using a simple cascade model we estimate the population fractions in these metastable levels. For the Mg6 + results, we find that the majority of the stored ions are in a metastable level, while for Mg7 + the metastable fraction is insignificant. We present the Mg6 + merged beams recombination rate coefficient for DR via N = 2 → N′ = 2 core electron excitations (ΔN = 0 DR) and for Mg7 + via 2 → 2 and 2 → 3 core excitations. Taking the estimated metastable populations into account, we compare our results to state-of-the-art multiconfiguration Breit-Pauli theoretical calculations. Significant differences are found at low energies where theory is known to be unreliable. Moreover, for both ions we observe a discrepancy between experiment and theory for ΔN = 0 DR involving capture into high-n Rydberg levels and where the stabilization is primarily due to a radiative transition of the excited core electron. This is consistent with previous DR experiments on M-shell iron ions which were performed at TSR. The large metastable content of the Mg6 + ion beam precludes generating a plasma recombination rate coefficient (PRRC). However, this is not an issue for Mg7 + and we present an experimentally derived Mg7 + PRRC for plasma temperatures from 400 K to 107 K with an estimated uncertainty of less than 27% at a 90% confidence level. We also provide a fit to our experimentally derived PRRC for use in plasma modeling codes. [ABSTRACT FROM AUTHOR]

The newly developed generalized density-dependent cluster model is employed to study the favored a transitions of exotic nuclei in both ground and isomeric states. We perform a systematic calculation for the ground and isomeric states of neutron-deficient isotopes ranging from Z = 67 to Z = 89. No adjustable parameter is introduced in our calculation. The theoretical a-decay half-lives are found to be in good agreement with the experimental data. This indicates that a unified description of a-decay half-lives for both ground and isomeric states is achieved by our model. [ABSTRACT FROM AUTHOR]