A photometric investigation of the asteroid (89) Julia

New photometric data of the light curve of the minor planet (89) Julia were obtained on nine nights during the 1972 opposition using the 60cm telescope at OHP. A synodic period of 11^h23^m14^s ± 7^s and an amplitude of 0.25mag were derived from the measurements. The light curve is rather unsymmetric and no plausible explanation for this has been offered so far. The measurements have been carried out in instrumental V′; the data obtained in B′ and U′ supplement all conclusions from V′ data concerning the rotation of Julia.     

Electrical coupling of the E- and F-regions and its effect on F-region drifts and winds

Electric currents, generated by thermospheric winds, flow along the geomagnetic field lines linking the E-and F-regions. Their effects on the electric field distribution are investigated by solving the electrical and dynamical equations. The input data include appropriate models of the F-region tidal winds, the thermospheric pressure distribution and the E-and F-layer concentrations. At the magnetic equator, the calculated neutral air wind at 240 km height has a prevailling eastward component of 55 m sec^-1 and the west-east and vertical ion drifts agree in their general form with incoherent scatter data from Jicamarca     

Further Evidence Suggestive of a Solar Influence on Nuclear Decay Rates

Recent analyses of nuclear decay data show evidence of variations suggestive of a solar influence. Analyses of datasets acquired at the Brookhaven National Laboratory (BNL) and at the Physikalisch-Technische Bundesanstalt (PTB) both show evidence of an annual periodicity and of periodicities with sidereal frequencies in the neighborhood of 12.25 year^?1 (at a significance level that we have estimated to be 10^?17). It is notable that this implied rotation rate is lower than that attributed to the solar radiative zone, suggestive of a slowly rotating solar core. This leads us to hypothesize that there may be an ??inner tachocline?? separating the core from the radiative zone, analogous to the ??outer tachocline?? that separates the radiative zone from the convection zone. The Rieger periodicity (which has a period of about 154 days, corresponding to a frequency of 2.37 year^?1) may be attributed to an r-mode oscillation with spherical-harmonic indices l=3,m=1, located in the outer tachocline. This suggests that we may test the hypothesis of a solar influence on nuclear decay rates by searching BNL and PTB data for evidence of a ??Rieger-like?? r-mode oscillation, with l=3,m=1, in the inner tachocline. The appropriate search band for such an oscillation is estimated to be 2.00??C?2.28 year^?1. We find, in both datasets, strong evidence of a periodicity at 2.11 year^?1. We estimate that the probability of obtaining these results by chance is 10^?12.     

Reaction rate calculation of d(α, γ)6Li process at low energy in framework of effective field theory

Reaction rate of the process d(α, γ)⁶Li has been calculated in the framework of Effective Field Theory (EFT) at low energy. Deuteron is assumed as a dibaryon in the initial state. The reaction amplitude for the initial P-wave states of deuteron-alpha and reaction rate for sum of E1 and E2 transitions are found in the framework of EFT up to NLO. Our results are in good agreement with the recent experimental data and the other theoretical works.     

d−α Radiative capture process by effective field theory

Two of the main components of nuclear fusion processes which occur in stars are the radiative capture of deuteron-alpha and its inverse reaction during which helium transforms into larger elements. One of the reactions occuring is the production of ⁶Li through the d(α, γ)⁶Li reaction that is supported by the Big Bang model. The process of radiation in the energy region 0.07 MeV ≤ E_cm ≤ 0.41 MeV has been studied in the framework of Effective Field Theory (EFT) at low energy. Further, within the EFT framework deuteron is assumed as a dibaryon and the coulomb effect between deuteron and alpha is ignored. The reaction amplitude for the P-wave initial states ³P₂, ³P₀ and ²P_3/2 and the astrophysical S-factor for sum of E₁ and E₂ transitions are found in the framework of EFT up to NLO. The results of this model for the astrophysical S-factor at low energies are comparable with the available experimental data and those of other theoretical models.     

The supernova remnant G78.2+2.1: New optical and X-ray observations

New optical and X-ray observations of the supernova remnant (SNR) G78.2+2.1 are presented. CCD Hα observations with a Fabry-Perot interferometer attached to the 125-cm reflector at the Crimean Station of the Sternberg Astronomical Institute are used to obtain the radial-velocity field toward the SNR and in its vicinity. The brightness distribution and X-ray spectrum of the SNR are obtained from archival ROSAT and ASCA X-ray data. The X-ray image of G78.2+2.1 exhibits a shell structure (ΔR/R?0.3) and is generally similar to its radio image; a comparison with the radio map at ν=1.4 GHz constructed from archival VLA data reveals the coincidence of features on scales of several arcminutes at the eastern boundary of G78.2+2.1. Weak X-ray emission (an outer shell or a halo of size ?2°) has been identified for the first time far outside G78.2+2.1. The X-ray emission from G78.2+2.1 is shown to characterize a young adiabatic SNR [M _X-ray ? 100 M _⊙, V _s?10³km s^?1, t?(5–6)×10³ years], which probably expands inside the cavity swept up by the progenitor's stellar wind. Searches for the corresponding radio structure are required to elucidate the nature of the outer X-ray shell or halo.     

Isotopic fractionation of methane in the martian atmosphere

The existence of methane in the martian atmosphere may be an indicator of subsurface life. Biological processes are known to fractionate the common isotopologues of methane, and hence measuring these isotopic ratios may yield constraints on the nature of the methane source. Any measurement of the isotopic ratios of atmospheric methane must consider the additional fractionation due to photochemistry in order to quantify the isotopic ratios of the source. Using a one-dimensional photochemical model, we find that photochemistry has a small (4.5‰) contribution to δ¹³C(CH₄) but has a large (114‰) contribution to δD(CH₄). Confirmation of these fractionation values will require additional laboratory data on key model inputs, particularly the ultraviolet absorption cross sections of ¹³CH₄ and kinetic rate coefficients for the reactions of ¹³CH₄ and CH₃D with OH and O(¹D) at pressures and temperatures relevant to the martian atmosphere.     

Polarimetric NIR reflectance measurements of regolith simulants at zero phase angle

Polarimetric reflectance measurements have been made at a wavelength of for a suite of predominantly lunar regolith simulants in support of development efforts for the BepiColombo Laser Altimeter (BELA). Measurements were made using an instrument at the University of Bern, Switzerland, that has been modified to accommodate photometric characterizations of laboratory samples down to 0^° phase angle (g) with linearly polarized illumination and a linearly polarized receiver. The data reveal opposition surges that are dominated by polarization state-conserving reflectance terms for all samples. Relative strengths of the trans-state reflectance terms are lowest for the darkest samples, suggesting that multiple scattering is responsible for state conversions. Normal albedo measurements of the lunar simulants range from 0.13 to 0.22 at zero illumination angle (i=0^°). The total reflectance of the regolith simulants at g=0^° were found to decrease with increasing i, which is inconsistent with predictions of reflectance models for Mercury. However, the g=0^° reflectance remains higher at i>0^° than would be expected for a gray Lambert surface that is scaled to the g=i=0^° reflectance value. Polarization ratios for reflectance under polarized illumination but unconstrained emission show that the samples scatter light in the in-plane polarization state more efficiently than in the transverse state at g=0^° and i>0^°. The opposite is true for g>0^° polarization ratios, which indicate that transverse polarized illumination scatters more efficiently at high g. The polarization effect appears to correlate with the sample's characteristic grain size, but the statistical basis of this trend is weak. The implications of these measurements upon the performance of the BELA instrument are discussed.     

The cascading of cosmic-ray nuclei in various media

More than a thousand interactions of primary heavy nuclei of the cosmic radiation with charge ≥10 and energy >1 GeV nucleon^?1 in nuclear emulsion have been studied with emphasis on how the primary nucleus fragments. It has been determined that the cases of multiple successive fragmentations that have been observed do not occur more frequently than expected. The fragmentation ofZ>20 nuclei does depend on the target nucleus to some extent so it is important to try to separate the interactions in emulsion by theirN _h (number of evaporation prongs). The fragmentation of ₈ ¹⁶ O at 2.1 GeV nucleon^?1 measured at the Bevalac shows a similar dependence on target nucleus. By using data from these new interactions combined with published data we have simulated on a computer nuclear cascades in both emulsion and air. Results on these cascades are given for both primary silicon and primary iron nuclei. These results are used to discuss the fluctuations expected in extensive air showers produced by heavy primary nuclei.     

Longitudinal variation of equatorial electrojet parameters derived from POGO satellite observations

A method of analysis has been developed making it possible to obtain electrojet parameters from vertical profiles of the POGO electrojet data. This has provided an unprecedented quantity of electrojet parameters—about 500 each of its peak eastward current intensity J₀, its total eastward current I₊, and its half width w—spanning through 360° longitude round the Earth, 5 h of daytime and September equinoctial months of the years 1967, 1968 and 1969. The daytime all-longitude averages of the parameters for the 3 years are 235 ± 14 km for w, 232 ± 63A km^?1 for J₀ and (54 ± 11) × 10³A for I₊. This first coverage round the globe shows that J₀ and I₊ vary considerably with longitude unlike w. While confirming the expected maximum of J₀ and I₊ at about 280°E longitude, we find that each of them also has an unexpected major maximum at about 100°E and a subsidiary maximum at 190°E longitude. The major maxima are found to be prominent only at hours near local noon. It is argued that the surprising longitudinal variations of J₀ and I₊ cannot be explained satisfactorily by variations in the upper mantle conductivity along the dip equator but possibly by longitudinal variations of wind systems and gradients at electrojet altitudes.     

Polarization of the H2O maser emission from Orion KL at epoch 2011.7

Polarization observations of the H₂O maser emission at 1.35 cm from the active region Orion KL were carried out at epoch 2011.7 on the Svetloe-Zelenchukskaya radio interferometer. The observational data have been processed on the correlator of the QUASAR network. Fragments of the structure have been identified; the line velocities and profile widths and the emission polarization have been determined. The component at the radial velocity V = 7.0 km s^?1 has been taken as a reference one. Its effective size in the Gaussian approximation is 1.5 mas, the axial ratio is Major/Minor = 3.3, and the orientation is PA = 11°. The component V = 7.6 km s^?1 corresponds to a bipolar outflow with an effective size of 6.2 mas, the axial ratio is Major/Minor = 5.3, and the orientation ?32°. The bipolar outflow is 10 mas away from the reference feature in the direction of 173°. The longitudinal velocity components of the NW and SE parts of the bipolar outflow in the local standard of rest are +0.15 and ?0.15 km s^?1, respectively. The degrees of polarization of the emission from the reference feature (7.0 km s^?1) and the bipolar outflow are m = 39 and 52%, respectively. The difference in polarization orientations of both components ?? _?? does not exceed 3°.     

A fast method for finding bound systems in numerical simulations: Results from the formation of asteroid binaries

We present a new code (companion) that identifies bound systems of particles in O(NlogN) time. Simple binaries consisting of pairs of mutually bound particles and complex hierarchies consisting of collections of mutually bound particles are identifiable with this code. In comparison, brute force binary search methods scale as O(N²) while full hierarchy searches can be as expensive as O(N³), making analysis highly inefficient for multiple data sets with N?¹⁰³. A simple test case is provided to illustrate the method. Timing tests demonstrating O(NlogN) scaling with the new code on real data are presented. We apply our method to data from asteroid satellite simulations [Durda et al., 2004. Icarus 167, 382-396; Erratum: Icarus 170, 242; reprinted article: Icarus 170, 243-257] and note interesting multi-particle configurations. The code is available at http://www.astro.umd.edu/zoe/companion/ and is distributed under the terms and conditions of the GNU Public License.     

Lower ionosphere electron densities from rocket measurements employing LF radio propagation and DC probe techniques

Electron densities throughout the D- and E-regions of the ionosphere have been measured during two rocket flights from Woomera, Australia; one in the daytime and one at night. The detailed distributions have a height resolution of much better than a km over the majority of the height range which was 66–175 km on the day flight and 83–184 km at night. This resolution has enabled sharp changes in electron density to be observed such as those associated with positive ion changes near 85 km (Reid 1970) and with sporadic-E layers.The detail and large dynamic range in electron density (10² to 3 × 10⁵ cm^?3) were achieved by combining the data from an LF radio propagation experiment with those from a probe experiment. The radio equipment allowed measurement of both the phase and amplitude of the wavefield above a ground transmitter. The method of deducing electron density from the phase velocity of the penetrating component of the wavefield is explained in detail. A comparison of the probe current and electron density has shown that the ratio between them varies slowly with height.     

Ion-ion recombination rates in the earth's atmosphere

The temperature dependence of the binary recombination coefficient, α₂, for the reaction NO⁺+NO₂^? → products has been obtained over the range 185–530 K. It is found that the corresponding mean cross section $\text{σ}$ is described by the power law $\text{σ}\text{? A · T}{}^{\mathrm{?0.9}}$, and that α₂ ? B · T^?0.4. Data has also been obtained for two cluster ion recombination reactions which indicate that their recombination cross sections are only about 40% larger than for the parent ions at a given temperature, the cross sections for these reactions also apparently increasing with decreasing temperature. In the light of this data and by considering the most probable positive and negative ions existing at various altitudes up to 90km in the atmosphere, the most appropriate ionic recombination coefficients in various altitude ranges are deduced. Thus, between 30 and 90 km, where the recombination process is two-body, the coefficient varies over the narrow range 5–9 × 10^?8 cm³s^?1, while below 30 km the process is predominantly three-body with an effective two-body rate increasing rapidly to a maximum value ≈3 × 10^?6 cm³s^?1 in the troposphere, these deductions being based on published laboratory determinations of three-body recombination coefficients.     

Interstellar extinction toward the ultradeep Galactic field of the Chandra observatory from 2MASS data

We have measured the interstellar extinction in the region of ultradeep Galactic-field observations by the Chandra telescope (l ^II, b ^II) ≈ 0.1–1.42 using photometric data from the 2MASS infrared allsky survey. The angular resolution of our interstellar extinction map is 1′.8. We show that the interstellar extinction has a minimum, A _V ～ 3.4, near the center of the Chandra field of view and increases to A _V ～ 5.8–6 at the edge of the field of view. In addition, we show that the bulk of the extinction is gained in the Galactic disk and is approximately the same for all bulge stars. Our results will be subsequently used to process the Chandra data and to estimate the properties of the stellar population in this region.     

Studies of microparticle impact phenomena leading to the development of a highly sensitive micrometeoroid detector

A highly sensitive device has been developed for the detection of micrometeoroids with masses extending down to and below the expected classical solar radiation pressure limit. This limit occurs at a mass of about 10⁻¹⁶ kg for a particle density of 3 × 10³ kg m⁻³. The detector operates on the principle that charge (Q) is released when a hypervelocity microparticle impacts on a solid surface. This process has previously been investigated at particle velocities (ν) greater than 1 km sec⁻¹ and the empirical relationship Q = Km^αν^β obtained where m is the particle mass and K, α and β are constants. In the present study the validity of this relationship has been demonstrated for iron particles with masses from 10⁻¹⁶ to 10⁻¹³ kg in the velocity range 0.05–1.4 km sec⁻¹ impacting on a molybdenum target. A value of α ≈ 1 is indicated and a value of β of 3.2 ± 0.4 has been obtained.     

Upper-atmosphere zonal winds determined from orbital analysis of Cosmos 482, 1972-23A

The orbit of Cosmos 482 has been determined at 55 epochs during the period August 1975–October 1977. Inclined at 52° to the Equator, of eccentricity exceeding 0.3 and perigee height near 210 km, this high drag and high eccentricity orbit is the most eccentric as yet analysed by PROP. The combination of the orbital characteristics, restricted global coverage of observational data, and the many observations of angular measurement at extreme range proved to be troublesome. Cleared of other perturbations, the inclination is analysed to determine the atmospheric rotation rate, λ rev day^?1, of the zonal winds at a height near 235 km. Results reveal a diurnal and seasonal dependence, including a summer value, averaged over local time, of λ = 0.9 and an evening value of λ = 1.4 in the winter months. The resultant wind velocities vary between 48 m s^?1 East to West and 193 m s^?1 West to East, with an average of 48 m s^?1 West to East.     

Tidal structures of z ∼ 1 galaxies in the Hubble Deep Field

An analysis of the images of objects in the Northern Hubble Space Telescope Deep Field has revealed twelve galaxies with tidal tails at redshifts from 0.5 to 1.5. The integrated characteristics of the newly discovered tidal structures are found to be similar to those of the tails of local interacting galaxies. The space density of galaxies with tidal tails is found to depend on z as (1+z)^4±1(q ₀=0.05), according to the data on objects with z=0.5–1.0. The exponent decreases to 3.6 if barred galaxies are included. The change in the rate of close encounters between galaxies of comparable masses (i.e., those that produce extended tidal structures) is estimated. If the rate of galactic mergers is governed by the same process, our data are indicative of the rapid evolution of galaxy merger rate toward z ～ 1.     

Gravity field and interior of Rhea from Cassini data analysis

The Cassini spacecraft encountered Rhea on November 26, 2005. Analysis of the Doppler data acquired at and around closest approach yields the mass of Rhea and the quadrupole moments of its gravity field with unprecedented accuracy. We obtained which corresponds to a density of . Our results for J₂ and C₂₂ are (7.947±0.892)×¹⁰⁻⁴ and (2.3526±0.0476)×¹⁰⁻⁴, respectively. These values are consistent with hydrostatic equilibrium. From the value of C₂₂, we infer the non-dimensional moment of inertia C/MR²=0.3721±0.0036. Our models of Rhea's interior based on the gravity data favor an almost undifferentiated satellite. A discontinuity between a core and a mantle is possible but not required by the data. Models with a constant silicate mass fraction throughout the body cannot account for the determined quadrupole coefficients. The data exclude fully differentiated models in which the core would be composed of unhydrated silicates and the mantle would be composed of pure ice. If the mantle contains 10% in mass of silicates, the core extends to 630 km in radius and has a silicate mass fraction of 40%. A continuous model in which the silicates are more concentrated toward the center of the body than in the outer layers is allowed by the gravity data but excluded by thermal evolution considerations. The one model that fits the gravity data and is self-consistent when energy transport and ice melting are qualitatively considered is an “almost undifferentiated” Rhea, in which a very large uniform core is surrounded by a relatively thin ice shell containing no rock at all.     

The cosmic age crisis and the Hubble constant in a non-expanding universe

The present paper outlines a cosmological paradigm based upon Dirac’s large number hypothesis and continual creation of matter in a closed static (nonexpanding) universe. The cosmological redshift is caused by the tired-light phenomenon originally proposed by Zwicky. It is shown that the tired-light cosmology together with continual matter creation has a universal Hubble constant H ₀=(512π ²/3)^1/6(GC ₀)^1/3 fixed by the universal rate C ₀ of matter creation, where G is Newton’s gravitational constant. It is also shown that a closed static universe has a finite age τ ₀=(243π ⁵/8GC ₀)^1/3 also fixed by the universal rate of matter creation. The invariant relationship H ₀ τ ₀=3π ²6^1/2 shows that a closed static universe is much older (≈one trillion years) than any expanding universe model based upon Big-Bang cosmology. It is this property of a static universe that resolves any cosmic age crisis provided that galaxy formation in the universe is a continual recurring process. Application of Dirac’s large number hypothesis gives a matter creation rate C ₀=4.6×10^?48 gm?cm^?3?s^?1 depending only on the fundamental constants of nature. Hence, the model shows that a closed static universe has a Hubble constant H ₀=70 km?s^?1?Mpc^?1 in good agreement with recent astronomical determinations of H ₀. By using the above numerical value for H ₀ together with observational data for elongated cellular-wall structures containing superclusters of galaxies, it is shown that the elongated cellular-wall configurations observed in the real universe are at least one hundred billion years old. Application of the microscopic laws of physics to the large-scale macroscopic universe leads to a static eternal cosmos endowed with a matter-antimatter symmetry. It is proposed that the matter-antimatter asymmetry is continuously created by particle-antiparticle pair annihilation occurring in episodic cosmological gamma-ray bursts observed in the real universe.