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10.
Hydrogen is the most abundant element in the universe. Molecular hydrogen is the dominant chemical species in the atmospheres of the giant planets. Because of their low masses, neutral and ionized hydrogen atoms are the dominant species in the high atmospheres of many planets. Finally, protons are the principal heavy component of the solar wind.Here we present a critical evaluation of the current state of understanding of the chemical reaction rates and collision cross sections for several important hydrogen collision processes in planetary atmospheres, ionospheres, and magnetospheres. Accurate ab initio quantum theory will play an important role. The collision processes are grouped as follows: - (a)
- H++H charge transfer,
- (b)
- H++H2(v) charge transfer and vibrational relaxation, and
- (c)
- H2(v,J)+H2 vibrational, rotational, and ortho-para relaxation.
In each case we provide explicit representations as tabulations or compact formulas. Particularly important conclusions are that H ++H 2( v) collisions are more likely to result in vibrational relaxation than charge transfer and H 2 ortho-para conversion is at least an order-of-magnitude faster than previously assumed. 相似文献
11.
The scientific rationale of the ROY multi-satellite mission addresses multiscale investigations of plasma processes in the key magnetospheric regions with strong plasma gradients, turbulence and magnetic field annihilation in the range from electron inertial length to MHD scales.The main scientific aims of ROY mission include explorations of: - (a)
- turbulence on a non-uniform background as a keystone for transport processes;
- (b)
- structures and jets in plasma flows associated with anomalously large concentration of kinetic energy; their impact on the energy balance and boundary formation;
- (c)
- transport barriers: plasma separation and mixing, Alfvenic collapse of magnetic field lines and turbulent dissipation of kinetic energy;
- (d)
- self-organized versus forced reconnection of magnetic field lines;
- (e)
- collisionless shocks, plasma discontinuities and associated particle acceleration processes.
In the case of autonomous operation, 4 mobile spacecrafts of about 200 kg mass with 60 kg payload equipped with electro-reactive plasma engines will provide 3D measurements at the scales of 100-10000 km and simultaneous 1D measurements at the scales 10-1000 km. The latter smaller scales will be scanned with the use of radio-tomography (phase-shift density measurements within the cone composed of 1 emitting and 3 receiving spacecrafts).We also discuss different opportunities for extra measurement points inside the ROY mission for simultaneous measurements at up to 3 scales for the common international fleet.Combined influence of intermittent turbulence and reconnection on the geomagnetic tail and on the nonlinear dynamics of boundary layers will be explored in situ with fast techniques including particle devices under development, providing plasma moments down to 30 ms resolution.We propose different options for joint measurements in conjunction with the SCOPE and other missions: - •
- simultaneous sampling of low- and high-latitudes magnetopause, bow shock and geomagnetic tail at the same local time;
- •
- tracing of magnetosheath streamlines from the bow shock to near-Earth geomagnetic tail;
- •
- passing “through” the SCOPE on the inbound orbit leg;
- •
- common measurements (with SCOPE and other equatorial spacecraft) at distances of ∼ few thousand km for durations of ∼several hours per orbit.
The orbit options and scientific payload of possible common interest are discussed in this work, including FREGAT cargo opportunities for extra payload launching and the “Swarm” campaigns with ejection of nano- and pico-satellites. 相似文献
12.
We have analysed the variations of inclination in 13 satellite orbits as they pass slowly, under the action of air drag, through 15th-order resonance with the geopotential, when successive equatorial crossings are 24° apart and the ground track repeats after 15 rev. The size and form of the change in inclination are determined mainly by the values of the geopotential harmonics of 15th order and odd degree, and (with l = 15, 17, 19, …) in the usual notation. Our analysis gives values of these coefficients up to l = 33 as follows: | l | 109C?l,15 | 109S?l,15 | | 15 | ?23.5 ± 0.8 | ?7.7 ± 0.8 | | 17 | 6.3 ± 1.5 | 5.6 ± 1.5 | | 19 | ?25.1 ± 2.5 | ?7.3 ± 2.3 | | 21 | 27.8 ± 3.6 | ?0.7 ± 3.4 | | 23 | 17.1 ± 4.1 | 13.9 ± 4.8 | | 25 | ?1.1 ± 3.0 | 8.5 ± 4.2 | | 27 | 10.0 ± 3.3 | 6.7 ± 2.7 | | 29 | ?9.4 ± 3.5 | 0.1 ± 4.7 | | 31 | 10.1 ± 5.4 | 3.8 ± 5.6 | | 33 | 1.1 ± 5.7 | 3.1 ± 5.8 | 相似文献
13.
The Earth's gravitational potential is now usually expressed in terms of a double series of tesseral harmonics with several hundred terms, up to order and degree at least 20. The harmonics of order 14 can be evaluated by analysing changes in satellite orbits which experience 14th-order resonance, when the track over the Earth repeats after 14 revolutions.In this paper we describe our first evaluation of individual 14th-order coefficients in the geopotential from analysis of the variations in inclination and eccentricity of satellite orbits passing through 14th-order resonance under the action of air drag. Using results from eleven satellites, we find the following values for normalized coefficients of harmonics of order 14 and degree l, C?l, 14 and S?l, 14, for l=14, 154. 22: | 109C? | 109S?l,14 | | - | - | - | | 14 | ?38.5 ±2.9 | ?7.8 ±2.2 | | 15 | 4.5 ±1.1 | ?23.8 ±0.3 | | 16 | ?22.3 ±3.6 | ?36.0 ±3.8 | | 17 | ?15.0 ±2.6 | 16.8 ±1.2 | | 18 | ?24.0±4.9 | ?3.2 ±3.7 | | 19 | ?1.6 ±2.8 | ?7.6 ±1.0 | | 20 | 8.8 ±5.8 | ?15.4 ±4.6 | | 21 | 18.2 ±3.6 | ?10.6 ±1.9 | | 22 | ?14.5 ±8.1 | 9.9 ±6.4 | 相似文献
14.
When a satellite orbit decaying slowly under the action of air drag experiences 15th-order resonance with the Earth's gravitational field, so that the ground track repeats after 15 rev, the orbital inclination suffers appreciable changes due to the perturbations from the harmonics in the geopotential of order 15 and odd degree (15,17,19 …). In this paper the changes in inclination at resonance of 11 satellites at inclinations between 30° and 90° have been analysed to determine values of the geopotential coefficients of order 15 and degree and in the usual notation. The recommended solution, going up to l = 31, is: | l | 109C?l,15 | 109S?l,15 | | 15 | ?21.5 ± 0.9 | ?8.4 ± 0.9 | | 17 | 4.4 ± 1.6 | 9.0 ± 1.5 | | 19 | ?15.6 ± 2.6 | ?14.1 ± 2.7 | | 21 | 10.4 ± 3.0 | 7.3 ± 3.5 | | 23 | 22.5 ± 2.8 | 1.2 ± 4.4 | | 25 | ?0.9 ± 4.7 | ?3.8 ± 5.3 | | 27 | ?11.2 ±3.3 | 9.1 ± 3.2 | | 29 | ?20.5 ± 5.4 | ?1.2 ± 6.1 | | 31 | 17.7 ± 6.6 | ?1.0 ± 7.1 | 相似文献
15.
It is shown that, at temperatures far below the triple point and under appropriate conditions, liquid water can stably or temporarily exist in upper ice-covered surfaces of planetary bodies (like Mars) in three different types: - (i)
- undercooled interfacial water (due to freezing point depression by van der Waals forces and “premelting”),
- (ii)
- water in brines (due to freezing point depression in solutions), and
- (iii)
- sub-surface melt water (due to a solid-state greenhouse effect driven heating).
The physics behind and the related conditions for these liquid waters to evolve and to exist, and possibly related consequences, are discussed. These calculations are mainly made in view of the possible presence of these sub-surface liquids in the upper surface of the present Mars. 相似文献
16.
Published determinations of the deceleration parameter qo based on various selected subsets are reviewed and a uniform re-determination is made according to a procedure given in /1/.The resulting q0-values from 8 largely independant samples of radio quasars all fall within the 4σ range obtained in /1/, namely, 1.0 ? q0 ? 3.5. The most important assumption made is that the characteristic luminosity of radio quasars is independant of the cosmic epoch. Thus, unless radio quasars at earlier times were much more luminous than the later ones, the universe is probably closed. 相似文献
17.
Two quasars SDSS J010013.02+280225.8 and J030642.51+185315.8 with redshifts z = 6.30 and z = 5.363 were recently discovered. Their apparent magnitudes in the standard cosmological model give the luminosities of Lbol ～ 4.3 × 10 14L⊙ and Lbol ～ 3.4 × 10 14L⊙. In the framework of modern concepts it is accepted that the energy release of quasars is provided by the accretion onto black holes with masses of 1.24 ± 0.19 × 10 10M⊙ and 1.07 ± 0.27 × 10 10M⊙. As within the standard cosmological model the ages of these objects are about one billion years, this creates serious difficulties for the scenario of formation of such objects. Here we interpret the ultra-high luminosities of quasars as the effect of lensing of their radiation by the foreground globular clusters or dwarf galaxies. 相似文献
18.
We present the results of spectroscopic and photometric studies of a new polar CRTS CSS130604 J 215427+155714, conducted at the telescopes of the SAO RAS. Analysis of the photometric series of observations allowed to clarify the orbital period of the system, P o = 0 . d 0672879 (±0.0000003). We build radial velocity curves and trace the intensity variations in the H β and H γ hydrogen lines and He II λ 4686 ?A ionized heliumline. Based on the H β and He II lines we build Doppler maps. It is shown that the line formation region is localized near the Lagrange point. The following parameter estimates of the system are obtained: M 1 = 0.83 ± 0.10 M ⊙, M 2 = 0.15 ± 0.01 M ⊙, q = M 2/ M 1 = 0.18 ± 0.03, i = 53? ± 5?. Based on the results of spectral, photometric and previously published polarimetric observations the possible geometric model of the system is discussed. 相似文献
19.
A summary is presented of our spectroscopic survey of comets extending for roughly 19 years from 1985 to 2004 comprising data for 92 comets of which 50 showed good emissions. All data were re-analyzed using consistent reduction techniques. Our observations of comets over several apparitions and comets observed over an extended period indicate no major changes in compositional classification. To our regret, no major unidentified cometary features were found in our surveyed spectral region of 5200-10400 Å. Absolute production rates for the dominant parent molecule H 2O and the daughter species C 2, NH 2 and CN are determined within the limits of the Haser model as are values for the dust continuum, Afρ. From these data, production rate ratios are calculated for C 2/H 2O, NH 2/H 2O, CN/H 2O and Afρ/H 2O. Excluding the odd Comets Yanaka (1988r), 43P/Wolf-Harrington and 19P/Borrelly, with unusual spectra, our set of comets exhibited relatively uniform composition. Detailed analyses of our data resulted in four taxonomic classes: - -
- Comets of typical composition (∼70%); exhibiting typical ratios with respect to water of C2, NH2, and CN.
- -
- Tempel 1 type (∼22%); having a deficiency in C2 but normal NH2 abundance.
- -
- G-Z type (∼6%); having both low C2 and NH2 ratios.
- -
- The unusual object Yanaka (1988r) (∼2%?); no detectable C2 or CN emission but normal NH2.
It is uncertain whether there is a clear separation between the comets of typical composition and those with C 2 depletion, or whether the latter consists of a group showing a continuum of decreasing C 2/CN ratios. Our spectroscopic investigations result in a visual record of the various compositional classes, which are illustrated in a number of figures. Production rate comparisons with the comet photometry program of Schleicher and A'Hearn [A'Hearn, M.F., and 4 colleagues, 1995. Icarus 118, 223-270] for 13 comets in common yielded good agreement once the different scale lengths are taken into account. An investigation into the possible origin of our compositional groups with respect to dynamical families of comets shows that the Halley family exhibits essentially no C 2 depletion. These objects were presumably formed in the region of Saturn and Uranus and scattered into the Oort cloud. Comets formed in the space near Neptune, responsible for the scattered Kuiper Belt show a mixture of “typical” and C 2 depleted objects, while we associate comets formed in-situ in the classical Kuiper belt with our C 2 depleted group. 相似文献
20.
We present the results of our processing of the first observations of extragalactic radio sources obtained with the eight-element International VLBI Network, which includes the Svetloe Russian Radio Astronomy Observatory equipped with a Mark 3A recording terminal. Our observations and their processing yielded highly accurate coordinates (in meters) of the Svetloe Observatory in the ITRF 2000 system: X = 2730173.854 ± 0.002, Y = 1562442.668 ± 0.004, Z = 5529969.069 ± 0.007. We also show that including the Svetloe Observatory in the International Network led to an appreciable improvement in the accuracy of determining the Earth’s rotation parameters (microarcseconds for the coordinates of the pole and nutation angles, microseconds for Universal Time): Xp = ?154683 ± 77, Yp = 361809 ± 59, UT1-UTC = ?325162.9 ± 2.5, Δ ψ = ?53147 ± 114, Δ ε = ?2286 ± 47. 相似文献
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