A comparison of density structures of a star forming and a non-star-forming globule

We present photometric and spectroscopic observations of one Trans-Neptunian Object (TNO 47171 1999 TC 36 ) and one Centaur (Thereus also named 32532 2001 PT 13 ). Near-infrared data were acquired with the ISAAC instrument at one of the 8 m telecopes of the Very Large Telescope (VLT, ESO-Cerro Paranal, Chile), while visible data were obtained with the EFOSC2 instrument on the 3.6 m telescope of La Silla (ESO, Chile). These observations were performed to search for rotational variations for both targets. Water ice has been confirmed on both objects. The surface composition models of the targets are presented and discussed, and are also compared to previous observations available in the literature.

We present a near-infrared extinction study of the dark globule L694-2, a starless core that shows strong evidence for inward motions in molecular line profiles. The J,H, and K band data were taken using the European Southern Observatory New Technology Telescope. The best fit simple spherical power law model has index p=2.6 +/- 0.2, over the 0.036--0.1 pc range in radius sampled in extinction. This power law slope is steeper than the value of p=2 for a singular isothermal sphere, the initial condition of the inside-out model for protostellar collapse. Including an additional extinction component along the line of sight further steepens the inferred profile. Fitting a Bonnor-Ebert sphere results in a super-critical value of the dimensionless radius xi_max=25 +/- 3. The unstable configuration of material may be related to the observed inward motions. The Bonnor-Ebert model matches the shape of the observed profile, but significantly underestimates the amount of extinction (by a factor of ~4). This discrepancy in normalization has also been found for the nearby protostellar core B335 (Harvey et al. 2001). A cylindrical density model with scale height H=0.0164+/- 0.002 pc viewed at a small inclination to the cylinder axis provides an equally good radial profile as a power law model, and reproduces the asymmetry of the core remarkably well. In addition, this model provides a basis for understanding the discrepancy in the normalization of the Bonnor-Ebert model, namely that L694-2 has prolate structure, with the full extent (mass) of the core being missed by assuming symmetry between the profiles in the plane of the sky and along the line-of-sight. If the core is sufficiently magnetized then fragmentation may be avoided, and later evolution might produce a protostar similar to B335.

High impact loading is known to prevent some of the age-related bone loss but its effects on the density distribution of cortical bone are relatively unknown. This study examined the effects of age and habitual sprinting on tibial and fibular mid-shaft bone traits (structural, cortical radial and polar bone mineral density distributions). Data from 67 habitual male sprinters aged 19-39 and 65-84years, and 60 non-athletic men (referents) aged 21-39 and 65-80years are reported. Tibial and fibular mid-shaft bone traits (strength strain index SSI, cortical density CoD, and polar and radial cortical density distributions) were assessed with peripheral quantitative computed tomography. Analysis of covariance (ANCOVA) adjusted for height and body mass indicated that the sprinters had 21% greater tibial SSI (P<0.001) compared to the referents, with no group×age-group interaction (P=0.54). At the fibula no group difference or group×age-group interaction was identified (P=0.12-0.81). For tibial radial density distribution ANCOVA indicated no group×radial division (P=0.50) or group×age-group×division interaction (P=0.63), whereas an age×radial division interaction was observed (P<0.001). For polar density distribution, no age-group×polar sector (P=0.21), group×polar sector (P=0.46), or group×age-group×polar sector interactions were detected (P=0.15). Habitual sprint training appears to maintain tibial bone strength, but not radial cortical density distribution into older age. Fibular bone strength appeared unaffected by habitual sprinting.

The behavior of poly(propylene imine) dendrimers at three different solution pH is investigated through molecular dynamics (MD) simulations in explicit solvent. MD simulations provide an insight into the conformational properties of dendrimers via the evaluation of their size, shape, radial density distribution, static structure factor, and scattering intensity. The size of the dendrimer increases from high solution pH to low pH. The internal structure of the dendrimer is quantified in terms of the radial atomic density profile and the terminal amine group density distribution. While the radial atomic density distribution shifts away from the core of the dendrimer with decreasing pH, a significant degree of back-folding of the outer generations is observed at high pH for higher generations of growth. Results from the structure factor and scattering intensity indicate two types of conformational transitions: (i) as a function of the solution pH, where the dendrimer evolves from an expanded structure at low pH to a highly compact one at high pH (except for higher generations), and (ii) with increasing generations, where the open structure of the dendrimer at lower generations transforms to a compact structure at higher generations at both high and low pH, characterized by a change in the fractal dimension.

Two phase cluster model in riser reactors: impact of radial density distribution on yields

Maximum values of one particle radial electronic density distribution has been calculated by using Hartree-Fock (HF)wave function with data published by[A. Sarsa et al. Atomic Data and Nuclear Data Tables 88 (2004) 163–202] for K and L shells for some Be-like ions. The Results confirm that there is a linear behavior restricted the increasing of maximum points of one particle radial electronic density distribution for K and L shells throughout some Be-like ions. This linear behavior can be described by using the nth term formula of arithmetic sequence, that can be used to calculate the maximum radial electronic density distribution for any ion within Be like ions for Z

Maximum values of one particle radial electronic density distribution has been calculated by using Hartree-Fock (HF)wave function with data published by[A. Sarsa et al. Atomic Data and Nuclear Data Tables 88 (2004) 163–202] for K and L shells for some Be-like ions. The Results confirm that there is a linear behavior restricted the increasing of maximum points of one particle radial electronic density distribution for K and L shells throughout some Be-like ions. This linear behavior can be described by using the nth term formula of arithmetic sequence, that can be used to calculate the maximum radial electronic density distribution for any ion within Be like ions for Z

The Kroll–Morton–Rosenbluth equations [IEEE J. Quantum Electron. QE-17, 1436 (1981)] for a helical-wiggler free-electron laser are generalized to treat an electron beam with a prescribed radial density profile and an equilibrium distribution function that is an arbitrary function of the longitudinal action J. The principal approximation is the assumption that betatron frequencies of beam particles are low compared with typical synchrotron frequencies. Vlasov equilibria for finite-amplitude primary waves with time-varying phase are calculated for several distribution functions. Using these equilibria, radial eigenvalue equations for the frequency and growth rate of small-amplitude sidebands are derived and solved numerically. The radial mode structure is found to have no appreciable effect on sideband growth when the beam radius is large compared with [2ks min(Ω0, dφ0/dz)]−1/2, where ks and φ0 are the wavenumber and phase of the primary wave and Ω0 is the maximum synchrotron ‘‘frequency’’ in z of trapped electrons. In these effectively one-dimensional cases, the dispersion relation depends only on the distribution function and on a dimensionless density parameter η̄=kwa2wω2b/(c2γ3rΩ30i), where kw is the wiggler wavenumber, aw=eAw/(mc2) is the dimensionless wiggler vector potential, ωb is the maximum plasma frequency of the beam, and γr is the Lorentz factor for resonant particles. Both the upper and lower sidebands for a deeply trapped distribution (J≊0) have a maximum growth rate of (31/2/2)(η̄2/2)1/3 for η̄≪1 and (31/2/2)(η̄/2)1/3 for η̄≫1, and distributions with a spread in J invariably show slower sideband growth. For beams with a smaller radius, the radial density variation causes a further reduction in the peak sideband growth rate and narrows the spectrum of unstable modes.

The impact of an inhomogeneous magnetic field generated by supplementary direct current (DC) coils on the uniformity of capacitively coupled discharges is examined utilizing a two-dimensional implicit particle-in-cell/Monte Carlo model. Typically, at low pressure, the radial density distribution of plasma is characterized by a high density at the center of the chamber and a lower density near the periphery. This results in non-uniform radial plasma density profiles and large ion impact angles at the electrode. We find that placing a DC coil above the chamber produces a non-uniform static magnetic field, which facilitates the transport of plasma species toward the electrode periphery, resulting in a more uniform plasma density distribution. Nonetheless, this approach leads to a decrease in central density and adversely affects the ion incident angles near the chamber’s center. Consequently, this compromise undermines both the efficiency and uniformity of processes occurring in the central region of the chamber. To overcome these limitations, we propose innovative coil configurations, specifically dual direct current (DC) coils comprising an inner and an outer coil. The outer coil, situated above the chamber, has a larger radius, while the inner coil, positioned either above or below the chamber, has a smaller radius. Additionally, the currents in the inner and outer coils flow in opposite directions. Our findings indicate that the outer coil predominantly governs the density distribution across the entire electrode surface, while the inner coil allows for precise adjustment of the plasma density near the discharge center. Therefore, by adjusting the currents of the outer and inner coils, significant improvements can be achieved in both the uniformity of plasma density and the vertical alignment of the ion angles above the electrode. These factors are critical for the fabrication of high aspect ratio microelectronic structures.

The orbital picture of shape resonances is investigated by examining the radial charge density distributions calculated from resonant Feynman–Dyson amplitudes for the 2P shape resonances in e-Be, e-Mg, and e-Ca scattering using the zeroth (bivariational self-consistent field), second order and the diagonal two particle one hole-Tamm–Dancoff approximation decouplings of the dilated electron propagator. A comparison between the radial density distributions from the highest occupied and the resonant orbital/Feynman–Dyson amplitude(s) reveals an accumulation of the electron density near the target for optimal value of the complex scaling parameter. The nodal pattern of the radial distributions differs from that expected for the lowest unoccupied p orbitals but their dominant contribution to the charge density distribution is clearly seen. A study of the difference between the radial densities obtained from various decoupling schemes highlights the role of correlation and relaxation in the characterization of these resonances. The role of coordinate space span of the primitive Gaussian-type orbital basis in characterization of these resonances is discussed.

We present a quantitative and relatively model-independent way to assess the radial structure of nearby AGN tori. These putative tori have been studied with long-baseline infrared (IR) interferometry, but the spatial scales probed are different for different objects. They are at various distances and also have different physical sizes that apparently scale with the luminosity of the central engine. Here we look at interferometric size information, or visibilities, as a function of spatial scales normalized by the size of the inner torus radius Rin. This approximately eliminates luminosity and distance dependence and, thus, provides a way to uniformly view the visibilities observed for various objects and at different wavelengths. We can construct a composite visibility curve over a wide range of spatial scales if different tori share a common radial structure. The currently available observations do suggest, independent of models, a common radial surface brightness distribution in the mid-IR that is roughly of a power-law form r −2 as a function of radius r and extends to ∼100 times Rin. Taking into account the temperature decrease toward outer radii with a simple torus model, this corresponds to the radial surface density distribution of dusty material directly illuminated by the central engine roughly in the range between r 0 and r −1 . This should be tested with further data.

The Global Seismographic Network (GSN)—a global network of ≈150 very broadband stations—is used by researchers to study the free oscillations of the Earth (≈0.3–10 mHz) following large earthquakes. Normal-mode observations can provide information about the radial density and anisotropic velocity structure of the Earth (including near the core–mantle boundary), but only when signal-to-noise ratios at very low frequencies are sufficiently high. Most normal-mode observations in the past three decades have been made using Streckeisen STS-1 vault seismometers. However, these sensors are no longer being manufactured or serviced. Candidate replacement sensors, the Streckeisen STS-6 and the Nanometrics T-360GSN, have been recently installed in boreholes, postholes, and vaults at several GSN stations and GSN testbeds. In this study, we examine normal-mode spectra following three Mw 8 earthquakes in 2021 and from one Mw 8.2 earthquake in 2014 to evaluate the change in GSN low-frequency performance on the vertical component. From this analysis, we conclude that the number of GSN stations capable of resolving normal modes following Mw 8 earthquakes has nearly doubled since 2014. The improved observational capabilities will help better understand the radial velocity and density estimates of the Earth.

We report on 13 sub-arcsecond binaries, detected by means of lunar occultations in the near-infrared at the ESO Very Large Telescope. They are all first-time detections, except for the visual binary HD~158122 which we resolved for the first time in the near infrared. The primaries have magnitudes in the range $K$=4.5 to 10.0, and the companions in the range $K$=6.8 to 11.1. The magnitude differences have a median value of 2.4, with the largest being 4.6. The projected separations are in the range 4 to 168 milliarcseconds with a median of 13 milliarcseconds. We discuss and compare our results with the available literature. With this paper, we conclude the mining for binary star detections in the volume of 1226 occultations recorded at the VLT with the ISAAC instrument. We expect that the majority of these binaries may be unresolvable by adaptive optics on current telescopes, and they might be challenging for long-baseline interferometry. However they constitute an interesting sample for future larger telescopes and for astrometric missions such as GAIA.

Surface composition and physical properties of several trans-neptunian objects from the Hapke scattering theory and Shkuratov model

Context. The study of the surface properties of Centaurs and trans-Neptunian objects (TNOs) provides essential information about the early conditions and evolution of the outer Solar System. Due to the faintness of most of these distant and icy bodies, photometry currently constitutes the best technique to survey a statistically significant number of them. Aims. Our aim is to investigate color properties of a large sample of minor bodies of the outer Solar System, and set their taxonomic classification. Methods. We carried out visible and near-infrared photometry of Centaurs and TNOs, making use, respectively, of the FORS2 and ISAAC instruments at the Very Large Telescope (European Southern Observatory). Using G-mode analysis, we derived taxonomic classifications according to the Barucci et al. (2005a, AJ, 130, 1291) system. Results. We report photometric observations of 31 objects, 10 of them have their colors reported for the first time ever. 28 Centaurs and TNOs have been assigned to a taxon. Conclusions. We combined the entire sample of 38 objects taxonomically classified in the framework of our programme (28 objects from this work; 10 objects from DeMeo et al. 2009a, A&A, 493, 283) with previously classified TNOs and Centaurs, looking for correlations between taxonomy and dynamics. We compared our photometric results to literature data, finding hints of heterogeneity for the surfaces of 4 objects.