On the Origin of Binary Transneptunian Objects

The observed transneptunian binaries, with components of comparable mass and large separations, cannot be the result of collisions in the present dynamical environment of the Kuiper belt. They could be produced by collision of two planetesimals within the sphere of influence of a third body during low-velocity accretion in the solar nebula. Thus, they are primordial.     

On the Origin of S0 Stellar Populations

We investigate a one-zone chemo-photometric evolutionary model of truncated spiral galaxies with and without starbursts in order to explore the origin of the spectrophotometric properties of S0s. First, we show that 1) the tight U-V colour–magnitude (CM) relation cannot reject the model with a starburst and 2) the model with a starburst can explain the difference in the I-K colour–magnitude relation between S0 galaxies and spiral galaxies. Next, we demonstrate how we can distinguish the truncated spirals with a starburst from those without a starburst by using the CaII–Hδ/λ4045 diagram (proposed by Leonardi and Rose, 1996) and the 1550-V colour. This revised version was published online in July 2006 with corrections to the Cover Date.     

On the Origin of the Last Meteorite Parent Bodies

The existence of gaps in the perihelion distribution of the orbits of multikilometer-sized asteroids that approach the orbits of terrestrial-group planets is confirmed. This property of the orbits of large asteroids suggests the existence among them of a family of last meteorite parent bodies. Astrophysical data were considered for S-asteroids of the Main Belt and those that approach terrestrial planets. The u–x color index, which is related to the position of the absorption band at 950 nm in the asteroid spectra, was chosen for a qualitative comparison of the surface composition of these asteroids (identical or differing composition). The u – x color-index distributions were analyzed statistically according to the perihelion (q) and mean heliocentric distances (a) of the S-asteroids. It is shown that these distributions are -shaped, peaking at q 1.8 AU and a 2.2 AU. The wings of the distributions can be approximated by linear regressions. A comparison of the u – x color-index mean values for S-asteroids in the regions of the Earth and Mars and of the Main Belt prompts the conclusion that the last meteorite parent bodies in the vicinity of the orbits of the Earth and Mars come primarily from various regions of the asteroid Main Belt.     

M 87核区X射线辐射起源的研究

利用耦合的吸积-喷流模型,对巨椭圆星系M 87(NGC 4486)核区的高分辨率观测到的多波段能谱分布进行了研究,重点是核区的X射线辐射起源问题.研究结果表明,M 87核区的X射线辐射是由喷流主导的,而不是此前认为的由径移主导的吸积流(ADAFs)主导的.     

Tektites: Size estimates of their source craters and implications for their origin

From estimates of the total masses of tektites in three strewnfields, calculations by Orphal et al. (1980) of the amount of melt that could be ejected from impact craters, and equations relating kinetic energy of impact to crater diameter, it is possible to calculate minimum diameters of lunar craters capable of ejecting the liquid masses that could have formed the various tektite strewnfields. No lunar craters of the requisite sizes have been found that are young enough to correlate with the dates of formations of the strewnfields and it seems clear that the Moon must be eliminated as a source of tektites on the Earth. It is concluded that the associations of the Ivory Coast tektites with the Bosumtwi crater and the moldavites with the Rieskessel are real and the tektites are of terrestrial origin. It follows that if the Ivory Coast tektites came from the 10.5-km-wide Bosumtwi crater, the larger masses in the Australasian and North American strewnfields came from craters 17 km in diameter and between 33 and 65 km in diameter, respectively. No crater has yet been proven to be the parent of the Australisian tektites. The large crater that formed the North American tektites may not yet have been found, although the Mistastin Lake Crater may eventually be proven to be the source.     

试论行星磁场强度分布的成因

行星磁场强度的分布具有规律性,中间巨行星的强度值大,两侧类地行星和远日行星的强度值小。在类地行星和远日行星中,也是中间行星磁场强度值大,如地球和海王星。两侧行星磁场强度值小,如金星、火星、天王星和冥王星。水星磁场强度值比金星大是因为水星环较早的从A组星云环中分裂出来所致。行星磁场强度大小分布的规律性与星云环级式分裂、环体物质中聚即铁磁性物质较快中聚的规律性一致。所以,铁磁性物质多少,可能是行星磁场强度大小分布的一个主要原因。     

On the Origin of Pulsations of Sub-THz Emission from Solar Flares

We propose a model to explain fast pulsations in sub-THz emission from solar flares. The model is based on the approach of a flaring loop as an equivalent electric circuit and explains the pulse-repetition rate, the high-quality factor, Q≥10³, low modulation depth, pulse synchronism at different frequencies, and the dependence of the pulse-repetition rate on the emission flux, observed by Kaufmann et al. (Astrophys. J. 697, 420, 2009). We solved the nonlinear equation for electric current oscillations using a Van der Pol method and found the steady-state value for the amplitude of the current oscillations. Using the pulse rate variation during the flare on 4 November 2003, we found a decrease of the electric current from 1.7×10¹² A in the flare maximum to 4×10¹⁰ A just after the burst. Our model is consistent with the plasma mechanism of sub-THz emission suggested recently by Zaitsev, Stepanov, and Melnikov (Astron. Lett. 39, 650, 2013).     

On a Theory of the Origin of Quasi-Harmonic Bursts on the Crab Pulsar

Astronomy Letters - The propagation and conditions for the escape of microwave radio emission from the local source of quasi-harmonic bursts that is a current sheet filled with an...     

On the Origin of the 1999 Leonid Storm as Deduced from Photographic Observations

Photographic multi-station observations of 18 Leonid meteorsobtained by the Spanish Photographic Meteor Network are presented. For each meteoroidthe radiant position, trajectory data and orbital parameters are discussed and compared totheoretical radiant positions and orbital elements of particles ejected from 55P/Tempel–Tuttle in 1899.We discuss the role of mean velocity imprecision in the dispersion of some orbital parameters,specially the semimajor axis. Finally, by applying the dust trail theory we have adjusted the1999 Leonidstorm orbits to a defined semimajor axis value to test the quality of photographic observations.     

On the Origin of the Spin of Planets and Stars and its Connection with Gravitomagnetism

The origin of the spin of planets and stars is, to a certain extent, still unexplained. In general, we attribute their rotation to the swirl of their constituent primitive gases. In this paper, we try to show that the rotation of celestial bodies depends only on their mass, apparent radius and tilt of their spin axes. We reach this conclusion within the framework of gravitomagnetism, implied by the Einstein’s general relativity theory (GR). Our results show that it might possible, in principle, to calculate the mass of spinning objects by measuring their apparent radius, the speed of rotation and the tilt of the axis of rotation.     

On the Origin of the Zebra Pattern with Pulsating Superfine Structures on 21 April 2002

Through the data around 3 GHz from the Radio Spectrometer in Huairou, Beijing, zebra-pattern structures from the 21 April 2002 event have been studied. Zebra stripes consist of periodically pulsating superfine structures in this event. An analysis of temporal profiles of intensities at multiple frequency channels shows that the Gaussian temporal profiles of pulse groups on zebra stripes are caused by drifting zebra stripes with Gaussian spectral profiles. The observed quasiperiodic pulsations with about 30 ms period have a peculiar feature of oscillation near a steady state, probably resulting from relaxation oscillations, which modulate the electron cyclotron maser emission that forms the zebra stripes during the process of wave – particle interactions. All the main properties of the zebra stripes with pulsating superfine structures indicate that the double plasma resonance model might be the most suitable one, with the relaxation oscillations, to form the superfine structures. The model of LaBelle et al. (Astrophys. J. 593, 1195, 2003) could not account for the observed properties of zebra-pattern structures in this event nor for most zebra-pattern structures occupying a wide frequency range, mainly because the allowable frequency range of the zebra-pattern structures in their model is too narrow to reproduce the observed zebras.     

Origin of the solar system

A theory for the origin of the solar system, which is based on ideas of supersonic turbulent convection and indicates the possibility that the original Laplacian hypothesis may by valid, is presented. We suggest that the first stage of the Sun's formation consisted of the condensation of CNO ices (i.e. H₂O, NH₃, CH₄,...) and later H₂, including He as impurity atoms, at interstellar densities to from a cloud of solid grains. These grains then migrate under gravity to their common centre of mass giving up almost two orders of magnitude of angular momentum through resistive interaction with residual gases which are tied, via the ions, to the interstellar magnetic field. Grains rich in CNO rapidly dominate the centre of the cloud at this stage, both giving up almost all of their angular momentum and forming a central chemical inhomogeneity which may account for the present low solar neutrino flux (Prentice, 1976). The rest of the grain cloud, when sufficiently compressed to sweep up the residual gases and go into free fall, is not threatened by rotational disruption until its mean size has shrunk to about the orbit of Neptune. When the central opacity rises sufficiently to halt the free collapse at central density near 10^?13 g cm^?3, corresponding to a mean cloud radius of 10⁴ R _⊙, we find that there is insufficient gravitational energy, for the vaporized cloud to acquire a complete hydrostatic equilibrium, even if a supersonic turbulent stress arising from the motions of convective elements becomes important, as Schatzman (1967) has proposed. Instead we suggest that the inner 3–4% of the cloud mass collapses freely all the way to stellar size to release sufficient energy to stabilize the rest of the infalling cloud. Our model of the early solar nebula thus consists of a small dense quasi-stellar core surrounded by a vast tenuous but opaque turbulent convective envelope. Following an earlier paper (Prentice, 1973) we show how the supersonic turbulent stress \((\rho _t v_t ^2 ) = \beta \rho GM(r)/r\) , where β is called the turbulence parameter, ρ is the gas density andM(r) the mass interior to radiusr causes the envelope to become very centrally condensed (i.e. drastically lowers its moment-of-inertia coefficientf) and leads to a very steep density inversion at its photosurface, as well as causing the interior to rotate like a solid body. As the nebula contracts conserving its angular momentum the ratio θ of centrifugal force to gravitational force at the equator steadily increases. In order to maintain pressure equilibrium at its photosurface, material is extruded outwards from the deep interior of the envelope to form a dense belt of non-turbulent gases at the equator which are free of turbulent viscosity. If the turbulence is sufficiently strong, we find that when θ→1 at equatorial radiusR _e=R₀, corresponding to the orbit of Neptune, the addition of any further mass to the equator causes the envelope to discontinuously withdraw to a new radiusR _e>R₀, leaving behind the circular belt of gas at the Kepler orbitR ₀. The protosun continues to contract inwards, again rotationally stabilizing itself by extruding fresh material to the equator, and eventually abandoning a second gaseous ring at radiusR ₁, and so on. If the collapse occurs homologously the sequence of orbital radiiR _n of the system of gaseous Laplacian rings satisfy the geometric progression $$R_n /R_{n + 1} = [1 + m/Mf]^2 = constant, n = 0, 1,2, \ldots ,$$ analogous to the Titius-Bode Law of planetary distances, wherem denotes the mass of the disposed ring andM the remaining mass of the envelope. Choosing a ratio of surface to central temperature for the envelope equal to about 10^?3 and adjusting the turbulence parameter β～~0.1 so thatR _n/R_n+1 matches the observed mean ratio of 1.73, we typically findf=0.01 and that the rings of gas each have about the same mass, namely 1000M _⊕ of the solar material. Detailed calculations which take into account non-homologous behaviour resulting from the changing mass fraction of dissociated H₂ in the nebula during the collapse do not appreciably disturb this result. This model of the contracting protosun enables us to account for the observed physical structure and mass distribution of the planetary system, as well as the chemistry. In a later Paper II we shall examine in detail the condensation of the planets from the system of gaseous rings.     

Origin of the Archean Earth impactors

A survey of current near-Earth asteroids and inner solar system comets suggests C class asteroids may have been the impactors during the Archean period resulting in the formation of spherule beds because of their carbonaceous composition and large diameters.     

Models for the Origin of the Quadrantids

We present two scenarios for production of the Quadrantid stream based on two different models for its origin: the extinct model in which 2003EH1 was an active comet that released the dust particles during past 5000 years, stopping its activity abruptly in AD 1488; and the split model; in which a catastrophic disruption of an asteroid at AD 1488 released a large number of dust particles in a single event. We calculate the orbital evolution of test particles released in both cases and derive the resulting size distribution of surviving meteoroids in the current Quadrantid stream in the form of s ^−α ds, where s denotes the radius of a meteoroid. We find α = 3.1 in the extinct model and 2.0 in the split model. In addition, the radius of the surviving meteoroids is derived as s >10 μm in the both models. We propose, based on our estimation of the infrared color ratio for the Quadrantid stream derived from both models, that infrared observations of the Quadrantid stream may determine which origin model is more reasonable.     

Origin of the late heavy bombardment

Cratering data from the Moon, Mars, and Mercury have been interpreted by some as evidence that the inner solar system underwent a period of intense bombardment that ended about 4 × 10⁹ yr ago. Planetary perturbations of small objects within the solar system seem unable to account for the effect. This paper suggests that stellar perturbations from members of the original open cluster within which the Sun formed triggered the brief flux of objects responsible for the bombardment.