On the mass determination of collapsed objects in close binaries: Applications to black-holes and neutron stars

Observational information required for determination of the masses of collapsed objects in close binaries is examined. Assumptions commonly used to evaluate the masses or thier lower limits, in the absence of the required observational data, are critically discussed. A reliable determination of the mass of a collapsed object in X-ray emitting binaries is yet to be made. No definitive case has been made for or against the existence of a black-hole in CygX-1.     

Recovery of entire shocked samples in a range of pressure from ~100 GPa to Hugoniot elastic limit

We carried out laser shock experiments and wholly recovered shocked olivine and quartz samples. We investigated the petrographic features based on optical micrographs of sliced samples and found that each recovered sample comprises three regions, I (optically dark), II (opaque), and III (transparent). Scanning electron microscopy combined with electron backscattered diffraction shows that there are no crystal features in the region I; the materials in the region I have once melted. Moreover, numerical calculations performed with the iSALE shock physics code suggest that the boundary between regions II and III corresponds to Hugoniot elastic limit (HEL). Thus, we succeeded in the recovery of the entire shocked samples experienced over a wide range of pressures from HEL (~10 GPa) to melting pressure (~100 GPa) in a hierarchical order.     

Generalized Lyzenga's Predictor of Shallow Water Depth for Multispectral Satellite Imagery

Multispectral satellite remote sensing can predict shallow-water depth distribution inexpensively and exhaustively, but it requires many in situ measurements for calibration. To extend its feasibility, we improved a recently developed technique, for the first time, to obtain a generalized predictor of depth. We used six WorldView-2 images and obtained a predictor that yielded a 0.648 m root-mean-square error against a dataset with a 5.544 m standard deviation of depth. The predictor can be used with as few as two pixels with known depth per image, or with no depth data, if only relative depth is needed.     

Experimental study on the impact fragmentation of core-mantle bodies: Implications for collisional disruption of rocky planetesimals with sintered core covered with porous mantle

Impact experiments of inhomogeneous targets such as layered bodies consisting of a dense core and porous mantle were conducted to clarify the effect of the layered structure on impact strength. The layered structure of small bodies could be the result of the thermal evolution of planetesimals in the solar nebula. So, the impact disruption of thermally evolved bodies with core-mantle structure is important for the origin of small bodies such as asteroids. We investigated the impact strength of rocky-layered bodies with porous mantle-sintered cores, which could be formed at an initial stage of thermal evolution. Spherical targets composed of soda-lime glass or quartz core and porous gypsum mantle were prepared as an analog of small bodies with a core-mantle structure, and the internal structure was changed. A nylon projectile was impacted at the impact velocity from 1 to 5 km/s. The impact strength of the core-mantle targets decreases with the increase of the core/target mass ratio (RCM) in the specific energy range from 1×¹⁰³ to 4×¹⁰⁴ J/kg. We observed two distinct destruction modes characterized by the damage to the core: one shows a damaged core and fractured mantle, and the other shows an intact core and broken mantle. The former mode was usually observed with increasing RCM, and the boundary condition of the core destruction () was experimentally found to be , where is the specific energy required to disrupt a glass core. From this empirical equation, it might be possible to discuss the destruction conditions of a thermally evolved body with a porous mantle-sintered core structure. We speculate that the impact strength of the body could be significantly reduced with the progress of internal evolution at the initial stage of thermal evolution.     

On the possibility of a geocoronal contribution to the celestial soft X-ray background

The possibility is investigated that a significant fraction of the X-ray background in the energy range 0.2–0.28 keV originates in the geocorona through bremsstrahlung. It is concluded that the geocoronal flux must be substantial at some times and the possibility exists that an observable geocoronal background exists at all times. The existing data on the soft X-ray background is found to be compatible with the hypothesis of a geocoronal component.     

Polycyclic aromatic hydrocarbons in the atmospheres of Titan and Jupiter

Polycyclic aromatic hydrocarbons (PAHs) are important components of the interstellar medium and carbonaceous chondrites, but have never been identified in the reducing atmospheres of the outer solar system. Incompletely characterized complex organic solids (tholins) produced by irradiating simulated Titan atmospheres reproduce well the observed UV/visible/IR optical constants of the Titan stratospheric haze. Titan tholin and a tholin generated in a crude simulation of the atmosphere of Jupiter are examined by two-step laser desorption/multiphoton ionization mass spectrometry. A range of two- to four-ring PAHs, some with one to four alkylation sites are identified, with net abundance approximately 10(-4) g g-1 (grams per gram) of tholins produced. Synchronous fluorescence techniques confirm this detection. Titan tholins have proportionately more one- and two-ring PAHs than do Jupiter tholins, which in turn have more four-ring and larger PAHs. The four-ringed PAH chrysene, prominent in some discussions of interstellar grains, is found in Jupiter tholins. Solid state 13C NMR spectroscopy suggests approximately equal to 25% of the total C in both tholins is tied up in aromatic and/or aliphatic alkenes. IR spectra indicate an upper limit in both tholins of approximately equal to 6% by mass in benzenes, heterocyclics, and PAHs with more than four rings. Condensed PAHs may contribute at most approximately 10% to the observed detached limb haze layers on Titan. As with interstellar PAHs, the synthesis route of planetary PAHs is likely to be via acetylene addition reactions.     

An isentropic vertical coordinate model: Design and application to atmospheric frontogenesis studies

Summary The isentropic vertical coordinate model developed at UCLA is briefly reviewed. The review includes an outline of the approach used to overcome technical difficulties in handling model layers with small mass.The model's performance is demonstrated by simulating the evolution of a middle-latitude baroclinic disturbance. During the evolution of the disturbance, sharp frontal zones are generated in the upper and middle troposphere with realistic tropopause folding. The extent to which different dynamical processes contribute to frontogenesis is analyzed.While the model successfully simulates frontogenesis in the upper and middle troposphere, it has a difficulty in simulating surface fronts. The difficulty arises due to the lack of degrees of freedom in surface temperatures since an isentropic vertical coordinate model requires a large number ofvertical layers to obtain a highhorizontal resolution at the lower boundary. This suggests the potential of a hybrid vertical coordinate, which approaches at upper levels and at lower levels.With 12 Figures     

Breakup of liquids by high velocity flow and size distribution of chondrules

As a new approach to understanding the chondrule formation process, we carried out aerodynamic experiments in which a liquid layer was attached to solid cores, and the breakup of this layer occurred by means of the interaction with a high-velocity gas flow. The size distribution of the dispersed droplets was investigated and compared with the size distributions of chondrules. Both distributions had an exponential form. Using the experimental results, the hydrodynamic pressure to produce the chondrule size distributions was estimated to be ∼ 10⁴ Pa.