The spectrum of comet C/2009 R1 (McNaught) in 4140–5240 Å wavelength region

The spectroscopic observations of comet C/2009 R1 (McNaught) were carried out with the 2 m Zeiss-RCC Telescope of Pik Terskol Observatory operated by the International Center for Astronomical and Medico-Ecological Research (Ukraine, Russia). The Multi Mode Cassegrain spectrometer was used to obtain spectra of moderate spectral resolving power with a wavelength coverage from 4140 to 5240 Å. The spectrum is characterized by the extremely low continuum level and strong molecular features. 192 emission lines of C₂, CN, CH, NH₂, CO⁺, and CH⁺ have been identified by the comparison of the observed and theoretical spectra of the molecules. The ratios of the gas production rates of Q(C₂)/Q(CN)=1.32, Q(CH)/Q(CN)=0.49, and Q(NH₂)/Q(CN)=0.81 were derived using a Haser model.     

Performance of the Tibet hybrid experiment (YAC-II + Tibet-III + MD) to measure the energy spectra of the light primary cosmic rays at energies 50–10,000 TeV

A new hybrid detector system has been constructed by the Tibet ASγ collaboration at Tibet, China, since 2014 to measure the chemical composition of cosmic rays around the knee in the wide energy range. They consist of an air-shower-core detector-grid (YAC-II) to detect high energy electromagnetic component, the Tibet air-shower array (Tibet-III) and a large underground water-Cherenkov muon-detector array (MD). We have carried out a detailed air-shower Monte Carlo (MC) simulation to study the performance of the hybrid detectors by using CORSIKA (version 6.204), which includes QGSJET01c and SIBYLL2.1 hadronic interaction models. Assumed primary cosmic ray models are based on helium poor, helium rich and Gaisser’s fit compositions around the knee. All detector responses are calculated using Geant4 (version 9.5) according to the real detector configurations and the MC events are reconstructed by the same procedure as the experimental data analysis. The energy determination is made by lateral density fitting (LDF) method using modified NKG function and the separation of the light components (proton, helium) is made by means of the artificial neural network (ANN) method and the random forest (RF) method. The systematic errors of the spectra of proton and helium caused by each steps of the analysis procedure are investigated including the dependence of the MC data on the hadronic interaction models and the primary composition models, and the algorithms for the primary mass identification. The systematic errors of the flux to be obtained by the new experiment are summarized as less than 30% in total. Our results show that the new hybrid experiment is powerful enough to study the chemical composition of the cosmic rays, in particular, to obtain the light-component spectra of the primary cosmic rays in 50–10,000 TeV energy range overlapping to the direct observation data at low energy side and ground-based indirect observations at high energy side. It is possible in this energy range to find the break points of the power indices of proton and helium (the knee of individual component spectrum) which are basically important parameter for the study of the cosmic-ray origin.     

A flux enhancement measured in energetic particles(E ∼ 60–100 keV) by the epona instrument aboard Giotto close to P⧸Grigg-Skjellerup,and its interpretationas the signature of a companion comet

A significant flux enhancement in energetic particles (E ∼ 60–⩾260 keV),showing internal fine structure interpreted to represent signatures produced during the traversalof various cometary boundaries in P⧸Grigg-Skjellerup, was recorded by the EPONA instrumentaboard spacecraft Giotto on 10 July 1992. A further internally structured flux enhancement withabout the same amplitude, recorded by EPONA in the energy range ∼60–100 keV but detected90×10³ km further on along the Giotto trajectory, is herein compared with theP⧸Grigg-Skjellerup record. Possible explanations for the second flux enhancement areindividually considered and it is suggested, on the basis of the available evidence, that itconstituted the signature of another smaller comet, either having a separate genesis from, ororiginating in a splitting of, the P⧸Grigg-Skjellerup nucleus.     

High fluences of low energy (10–25 MeV/amu) C,N, O and heavier ions at 450 km altitude; results from the skylab experiment

High fluences (i.e. the integrated fluxes) of C, N, O group of nuclei and some of the heavier ones, in the energy interval 10–25 MeV/amu, have been identified in a Lexan polycarbonate detector assembly exposed on the exterior of the Skylab for 73 days. The existence of large flux of low energy nuclei in the Skylab orbit is surprising since the minimum geomagnetic cut-off energy for fully stripped nuclei (A/Z=2) is 50 MeV/amu at the orbit of the satellite, and the period of exposure was a quiet one, free from significant solar particle events. We have considered two sources for these particles: (i) partly ionized interplanetary ions accelerated within the magnetosphere and (ii) heavy nuclei trapped in the Earth's radiation belt. The flux and composition of the nuclei observed by us seem to be significantly different from those in the trapped radiation as known at present; hence it seems likely that the major part of the observed flux may be interpreted, in terms of partly ionized interplanetary ions that are further accelerated in the magnetosphere.     

The behaviour of outer radiation belt electrons (> 1·5 MeV) during a geomagnetically disturbed time on 8 March 1970 and its relationship to magnetospheric processes

Omnidirectional intensities of electrons with energies E_e > 1·5 MeV detected by a low orbiting polar satellite (GRS-A/AZUR) in the outer radiation belt are examined during disturbed times including the main phase of a very strong geomagnetic storm on 8 March 1970. The particle intensity features are discussed in relationship with proposed magnetospheric processes. It is found that a superposition of the two following effects can explain the particle behavior in the trapping region:(A) Radial diffusion. After the southward turning of the interplanetary field an inward motion of both the energetic electron belt and the plasmapause took place. This effect was observed at L > 3 R_E and we attribute it to enhanced magnetospheric electric field fluctuations. Later, a strong interplanetary shock impinged upon the magnetosphere which was related to the triggering of intense magnetospheric substorms; a further inward diffusion occurred at L ? 3 R_E, accompanied by an inward movement of the electron slot. A rough estimation of the diffusion coefficient leads to a power spectrum of the electric field fluctuations which seems to be consistent with experimentally determined power spectra (Mozer, 1971).(B) Adiabatic response to ring current changes. Large energetic electron intensity decreases within the outer radiation belt are shown to be adiabatic changes due to ring current variations. The influence of the inflation of the magnetosphere due to the developing ring current is simultaneously observed by the decrease of the solar proton outoff (1·7-2·5 MeV).