Late-time emission of the type II Supernovae powered by the radioactive decay56Ni−56Co−56Fe

A one-zone model for the late time SN II energized by the radioactive decay⁵⁶Ni–⁵⁶Co–⁵⁶Fe is presented. The model succeeds in reproducing for the late time evolution of H and [Oi] 6300 emission lines in SN1970g for the reasonable set of parameters: mass of ejecta 4M , boundary velocityv ₀=4000 km s^–1 and amount of⁵⁶NiM _Ni=0.02M . However, a one-zone model does not account for the late time continuum. In the case of SN1980k the radioactive model fits H and [Oi] 6300 emissions att250 day satisfactory but fails at very late time, e.g.,t=670 day when the predicted value of the ratioL(H)/L(6300) is two orders of magnitude smaller than the observed one. We suggest that the strong H emission in SN1980k on the 670th day is due to the interaction of the supernova envelope with the pre-SN wind. The radioactive model for the late time SN II predicts strong Mgii 2800 line and detectable Hei 10830 line in emission and absorption.     

The stability parameters of three-dimensional periodic three-body orbits

Formulae containing the elements of the variational matrix are obtained which determine the linear isoenergetic stability parameters of three-dimensional periodic orbits of the general three-boy problem. This requires the numerical integration of the variational equations but produces the stability parameters with the effective accuracy of the numerical integration. The conditions for stability, criticality, and bifurcations are briefly examined and the stability determination procedure is tested in the determination of some three-dimensional periodic orbits of low inclination bifurcating from vertical-critical coplanar orbits.     

Sub-iron to iron nuclei in low-energy (50–200 MeV nucl−1) cosmic rays as observed in the Skylab experiment

In this paper we present our most recent results on the sub-iron (Sc to Cr) to Fe nuclei abundance ratios in the low-energy cosmic rays of 50 to 250 MeV nucl.^–1 and their implications as observed in theSkylab experiment. In view of the importance of this ratio in determining the cosmic-ray pathlength in interstellar medium, we have obtained additional data in the same detector module and the results of final analysis are reported. Charge determinations in the Lexan detector were made from an average of about four independent measurements ofZ for each of the cosmic-ray events and the mean charge resolution is obtained asZ/Z0.2. From about 100 events of calcium to nickel in low-energy cosmic rays, sub-iron (Sc to Cr) to Fe–Co ratio is determined as 1.43±0.40 in 50–250 MeV nucl.^–1. This shows a large energy dependence of the ratio as compared to the value of 0.4–0.8 in 200–1000 MeV nucl.^–1 as measured by many investigators. The origin of this large enhancement of the ratios in low-energy cosmic rays is not known at present. Some possible suggestions are briefly mentioned.     

Large-scale structure of background fields and active regions

An attempt is made to study the relations between emergence of active regions and the solar background large-scale structures on the basis of Solar Geophysical Data, including Kitt-Peak magnetograms, H filtergrams, and Ca images.The emergence of 217 active regions (a.r.s) that have appeared on the solar disk not farther than ± 60° from the central meridian is studied. The a.r.s are divided into two classes A and B according to their birth location. Class A contains a.r.s emerged far (8–10°) from the background field boundaries, and class B- those emerged near to (55°) or just at the boundaries.It was found that a.r.s of class A differ appreciably from those of class B; in particular, the dimensions and the intensity (S, I) of class B a.r.s are nearly twice as large as those of class A. For class A a.r.s some alterations of the solar large-scale structure boundaries were found in 15% of all the cases, whereas for those of class B in 60%.     

The lunar geochemistry of chromium and vanadium

Crystal/liquid partition coefficients for Cr, V, Mn, and Fe have been determined experimentally between olivine, orthopyroxene, clinopyroxene and silicate melt possesing the composition of a primitive lunar green glass, at oxygen fugacities appropriate to the lunar interior. These species all behave essentially as compatible elements and possess crystal/liquid partition coefficients mostly between 0.3 and 0.9. Partition coefficients for Cr, V, and Mn are generally similar to those of Fe. This implies that crystal/liquid fractionation processes in the lunar interior which do not involve the participation of spinels would not have been effective in fractionating MnO, CrO, and VO from FeO. The well-known constancy of FeO/MnO ratios in nearly all lunar rocks is a reflection of this behaviour. It is shown that comparably strong correlations between CrO-;FeO and VO-;FeO exist for lunar highland breccias and soils from all sites and that these correlations extend to primitive lunar volcanic glasses associated with mare volcanism, strongly suggesting that the CrO/FeO and VO/FeO ratios so derived are of global importance. The observed ratios characterizing differentiated regions of the Moon can be combined with the corresponding ratios for residual refractory portions of the Moon, using measured partition coefficients for Fe, Mg, Cr, V, and Mn between olivine, orthopyroxene and liquid. Bulk Moon abundances for Cr and V have been calculated for a range of reasonable assumptions concerning the petrogenetic relationships between differentiated portions of the Moon and complementary refractory residua consisting of olivine and orthopyroxene mineralogies. Because of the small differences in crystal liquid partition coefficients between FeO, CrO, and VO, these estimates are insensitive to large variations in the models. The bulk Moon is accordingly estimated to contain 2190–2463 ppm Cr and 79–95 ppm V. These values are very similar to the Cr and V contents of the Earth's mantle, estimated as 3010 ppm Cr and 81 ppm V by Sun (1982). The geochemical implications of these similarities are discussed.     

Identification of the interstellar cyanomethyl radical (CH2CN) in the molecular clouds TMC-1 and Sagittarius B2

We report the astronomical identification of the cyanomethyl radical, CH2CN, the heaviest nonlinear molecular radical to be identified in interstellar clouds. The complex fine and hyperfine structures of the lowest rotational transitions at about 20.12 and 40.24 GHz are resolved in TMC-1, where the abundance appears to be about 5 x 10(-9) relative to that of H2. This is significantly greater than the observed abundance of CH3CN (methyl cyanide) in TMC-1. In Sgr B2 the hyperfine structure is blended in the higher frequency transitions at 40, 80, and 100 GHz, although the spin-rotation doubling is clearly evident. Preliminary searches in other sources indicate that the distribution of CH2CN is similar to that for such carbon chain species as HC3N or C4H.     

Combustion as the cause of comet P/Halley's activity

The totality of the results obtained in the VEGA, GIOTTO and SUISEI projects does not lend itself to interpretation within the old sublimation models of comet activity considering solar radiation as the sole source of energy. Among them are the systematic excess of the velocity and temperature of the gas escaping from the nucleus over the theoretical values, the outflow being concentrated in several ( ~ 12–15) narrow ( ~ 300 m in size at the nucleus) hypersonic jets carrying very large amounts of remarkably fine CHON dust and located along continuous lines on the nuclear surface, intense release from the nucleus or very close to it (2 × 10³km) of CO (Q _Co/Q _{H2 O} = 0.05–0.2) with a smaller amount of CO₂ (Q _{CO 2}/ Q _{H2 O} 0.015), large near-nucleus abundances of C, C⁺ (Q _C/Q _CO 0.29), etc.The new observations, together with some earlier data still poorly understood (e.g. the appearance in the coma of large amounts of C₃) can be accounted for by assuming the cometary ices to contain, apart from hydrocarbons, nitrogen-containing compounds, etc. also of free oxygen ( ~ 15 wt.%). Under these conditions, burning should occur in the products of sublimation under deficiency of oxidizer accompanied by the production of soot, smoke, etc. The burning should propagate under the surface crust and localize primarily at a few sites.The presence of oxygen in cometary ices follows from a new eruption theory assuming the minor bodies of the Solar System to have formed in explosions of the massive ice envelopes saturated by electrolysis products on distant moonlike bodies of the type of Ganymede and Callisto.     

Space charge sheath in plasma-neutral gas interaction

A space charge sheath is found to be formed whenever a high-velocity magnetized plasma stream penetrates a gas cloud. The sheath is always located at the head of the plasma stream, and its thickness is very small compared to the length of the plasma stream. Soon after the sheath is formed it quickly slows down to the Alfvén critical velocity. The plasma behind the sheath continues to move at higher velocity until the whole plasma stream is retarded to the critical velocity. In the interaction at gas density 10¹⁹ m^–3 the sheaths are observed to be accompanied by a single loop of current with current density of 10⁵ Å m^–2. Maximum potential in the sheath ranges between 50 and 200 V.Presently available models for the sheath may explain the initiation of the sheath formation. Physical processes like heating of the electrons and ionization of the gas cloud which come into play at a later stage of the interaction are not included in these models. These processes considerably alter the potential structure in the sheath region. A schematic model of the observed sheath is presented here.Experiments reveal a threshold value of the magnetic field for plasma retardation to occur. This seems to correspond to the threshold condition for excitation of the modified two-stream instability which can lead to the electron heating. The observed current are found sufficient to account for the plasma retardation at a gas density of 10¹⁷ m^–3.     

A spectroscopic study of the microorganism model of interstellar grains

The microorganism model of interstellar grains is investigated by spectroscopy from the infrared (IR), visible to the ultraviolet (UV) wave regions.E. coli, yeast and spores ofBacillus subtilis exhibit absorption bands at =3.1 and 9.7 m; they also exhibit several absorptions at 68 m which are in agreement with the observed IS extinction curves.To obtain the extinction curves in the visible and UV regions, dry films of microorganism are prepared on a MgF₂ plate or synthesized quartz plate and their spectra measured. In the wavelength region 190400 nm, conventional spectrophotometers are adopted for the measurement. The extinction curve of the film ofE. coli is similar to the observed IS curve.For the wave-range 100<<400 nm, a vacuum UV spectrometer is adopted to avoid absorptions due to O₂ in the atmosphere. The extinction spectra by this method are in agreement with the result obtained by the conventional method where comparison is possible. The extinction curves ofE. coli and yeast are such that they incrase towards the short wavelength and exhibit a peak at -190 nm, which is different from the well-known IS peak at =220 nm. It remains to be seen whether interstellar low temperatures (1040 K) can shift the peak position in the extinction curve of biochemical materials.     

Development of a real-time algorithm for detection of solar wind discontinuities

A study is presented of an algorithm, based on the statistical analysis of interplanetary magnetic field data, for the real-time detection of discontinuities in the solar wind. The analysis is based on the application of a sliding or searching algorithm together with a minimum variance treatment. A demonstration is given for a Pioneer data set from 29 August, 1966. This particular data set was chosen because it has been extensively studied (in terms of the fast forward MHD shock wave) by previous groups who utilized the three-dimensional Rankine-Hugoniot shock equations after identifying the shock on a subjective basis. Our procedure differs in that it is perfectly objective because of its searching technique. For this particular data set we identify the original shock with excellent agreement with the earlier studies of its normal vector, as well as an additional shock and tangential discontinuity, neither of which had been identified previously.