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1.
Simultaneous measurements of NO and NO2 in the stratosphere leading to an NOx determination have been performed by means of i.r. absorption spectrometry using the Sun as a source in the 5·2 μm band of NO and in the 6·2 μm band of NO2. The observed abundance of NOP peaks at 26 km where it is equal to (4·2 ± 1) × 109 cm?3. The volume mixing ratio of NOp was observed to vary from 1·3 × 10?9 at 20 km to 1·3 × 10?8 at 34 km.  相似文献   

2.
W.A. Traub  N.P. Carleton 《Icarus》1974,23(4):585-589
A spectroscopic search for H2O and CH4 in Comet Kohoutek (1973f) was made using a Pepsios interferometer. No evidence was found for either molecule, allowing us to set an upper limit on their production rates (on about 21 January 1974) of Q(H2O) < 6.2 × 1028 sec?1 and Q(CH4) < 2.0 × 1030 sec?1. If the cometary surface is water-ice, this production rate leads to a product (1 ? A)·(πR02) < 2.2 km2, where A is the Bond albedo, R0 is the nuclear radius, and we assume that all the absorbed solar energy is used to evaporate H2O.  相似文献   

3.
Interference filter photometry was taken of Comet Encke on June 14, 1974 (1.07 AU heliocentric distance, postperihelion) at the CTIO (Cerro Tololo Interamerican Observatory) 150-cm reflector. Production rates were calculated of 4.1 × 1023 mol sec?1 of CN, 5.3 × 1023 mol sec?1 of C3, and 4.3 × 1024 mol sec?1 of C2. These are about three times smaller than at comparable heliocentric distance preperihelion, assuming a value of 100 for the ratio H2O/ (C2 + C3 + CN). An upper limit was placed on the production of nonvolatiles at about one-third that of volatiles in mass by assuming a bulk density of 1 g cm?3, a particle geometric albedo of 0.1, and a phase function of 0.2.  相似文献   

4.
Results of the scattered solar radiation spectrum measurements made deep in the Venus atmosphere by the Venera 11 and 12 descent probes are presented. The instrument had two channels: spectrometric (to measure downward radiation in the range 0.45 < γ < 1.17 μm) and photometric (four filters and circular angle scanning in an almost vertical plane). Spectra and angular scans were made in the height range from 63 km above the planet surface. The integral flux of solar radiation is 90 ± 12 W m?2 measured on the surface at the subsolar point. The mean value of surface absorbed radiation flux per planetary unit area is 17.5 ± 2.3 W m?2. For Venera 11 and 12 landing sites the atmospheric absorbed radiation flux is ~15 W m?2 for H >; 43 km and ~45 W m?2 for H < 48 km in the range 0.45 to 1.55 μm. At the landing sites of the two probes the investigated portion of the cloud layer has almost the same structure: it consists of three parts with boundaries between them at about 51 and 57 km. The base of clouds is near 48 km above the surface. The optical depth of the cloud layer (below 63 km) in the range 0.5 to 1 μm does not depend on the wavelength and is ~29 and ~38 for the Venera 11 and 12 landing sites, respectively. The single-scattering albedo, ω0, in the clouds is very close to 1 outside the absorption bands. Below 58 km the parameter (1 ? ω0) is <10?3 for 0.49 and 0.7 μm. The parameter (1 ? ω0) obviously increases above 60 km. Below 48 km some aerosol is present. The optical depth here is a strong function of wavelength. It varies from 1.5 to 3 at λ = 0.49 μm and from 0.13 to 0.4 at 1.0 μm. The mean size of particles below the cloud deck is about 0.1 μm. Below 35 km true absorption was found at λ < 0.55 μm with the (1 ? ω0) maximum at H ≈ 15 km. The wavelength and height dependence of the absorption coefficient are compatible with the assumption that sulfur with a mixing ratio ~2 × 10?8 normalized to S2 molecules is the absorber. The upper limits of the mixing ratio for Cl2, Br2, and NO2 are 4 × 10?8, 2 × 10?11, and 4 × 10?10, respectively. The CO2 and H2O bands are confidently identified in the observed spectra. The mean value of the H2O mixing ratio is 3 × 10?5 < FH2O < 10?4 in the undercloud atmosphere. The H2O mixing ratio evidently varies with height. The most probable profile is characterized by a gradual increase from FH2O = 2 × 10?5 near the surface to a 10 to 20 times higher value in the clouds.  相似文献   

5.
We present some results about the continuation of doubly-symmetric horseshoe orbits in the general planar three-body problem. This is done by means of solving a boundary value problem with one free parameter which is the quotient of the masses of two bodies μ 3=m 3/m 1, keeping constant μ 2=m 2/m 1 (m 1 represents the mass of a big planet whereas m 2 and m 3 of minor bodies). For the numerical continuation of the horseshoe orbits we have considered m 2/m 1=3.5×10?4, and the variation of μ 3 from 3.5×10?4 to 9.7×10?5 or vice versa, depending on the orbit selected as “seed”. We discuss some issues related to the periodicity and symmetry of the orbits. We study the stability of some of them taking the limit μ 3→0. The numerical continuation was done using the software AUTO.  相似文献   

6.
The radio radii of the Sun at wavelengths of 5, 10.7, 12, and 95 cm have been determined from eclipse observations as R5 ?? (1.0 ± 0.015)R ??, R 10,12 = (1.05 ± 0.003)R ??, and R 95 = (1.2 ± 0.02)R ??. The bright-ness temperatures of quiet solar disk areas at these wavelengths have turned out to be Td 5 = (22 ± 2) × 103, Td 10 = (44 ± 3) × 103, Td 12 = (47 ± 3) × 103, and Td 95 = (1000 ± 30) × 103 K. There were local sources of radio emission with angular sizes from 1.9 to 2.4 arcmin and brightness temperatures from 80 × 103 to 1.75 × 106 K above sunspot groups at short wavelengths of 5, 10.7, and 12 cm. The radio flux from the local sources at 95 cm turned out to be below the detection threshold of 1.0 × 10?22 W m?2 Hz?1. Comparison of the values obtained with the results of observations of another eclipse on August 1, 2008, occurred at the epoch of minimum of the 11-year solar cycle has shown that the radio radius of the Sun at 10.7 and 12 cm increased from 1.016 R ?? to 1.05 ± 0.003R ??, the height of the emitting layer at these wavelengths moved from 11 × 103 km to (30 ± 7) × 103 K, and the brightness temperature of the quiet Sun rose from (35.8 ± 0.4) × 103 K to (44 ± 3) × 103 K at 10.7 cm and from (37.3 ± 0.4) × 103 K to (47 ± 3) × 103 K at 12 cm. Consequently, the parameters of the solar atmosphere changed noticeably in 2 years in connection with the beginning of the new solar cycle 24. The almost complete absence of local sources at the longest wavelength of 95 cm suggests that the magnetic fields of the sunspot groups on January 4, 2011, were weak and did not penetrate to the height from where their emission could originate. If this property is inherent in most sunspot groups of cycle 24, then it can be responsible for its low flare activity.  相似文献   

7.
The results of JHKLM photometry for Nova Delphini 2013 obtained in the first sixty days after its outburst are analyzed. Analysis of the energy distribution in a wide spectral range (0.36–5 µm) has shown that the source mimics the emission of normal supergiants of spectral types B5 and A0 for two dates near its optical brightness maximum, August 15.94 UT and August 16.86 UT, respectively. The distance to the nova has been estimated to be D ≈ 3 kpc. For these dates, the following parameters have been estimated: the source’s bolometric fluxes ~9 × 10?7 and ~7.2 × 10?7 erg s?1 cm?2, luminosities L ≈ 2.5 × 105 L and ≈2 × 105 L , and radii R ≈ 6.3 × 1012 and ≈1.2 × 1013 cm. The nova’s expansion velocity near its optical brightness maximum was ~700 km s?1. An infrared (IR) excess associated with the formation of a dust shell is shown to have appeared in the energy distribution one month after the optical brightness maximum. The parameters of the dust component have been estimated for two dates of observations, JD2456557.28 (September 21, 2013) and JD2456577.18 (October 11, 2013). For these dates, the dust shell parameters have been estimated: the color temperatures ≈1500 and ≈1200 K, radii ≈6.5 × 1013 and 1.7 × 1014 cm, luminosities ~4 × 103 L and ~1.1 × 104 L , and the dust mass ~1.6 × 1024 and ~1025 g. The total mass of the material ejected in twenty days (gas + dust) could reach ~1.1 × 10?6 M . The rate of dust supply to the nova shell was ~8 × 10?8 M yr?1. The expansion velocity of the dust shell was about 600 km s?1.  相似文献   

8.
Previous studies based on radio scintillation measurements of the atmosphere of Venus have identified two regions of small-scale temperature fluctuations located in the vicinity of 45 and 60 km. A global study of the fluctuations near 60 km, which are consistent with wind-shear-generated turbulence, was conducted using the Pioneer Venus measurements. The structure constants of refractive index fluctuations cn2 and temperature fluctuations cT2 increase poleward, peak near 70° latitude, and decrease over the pole; cn2 varies from 2 × 10?15 to 1.5 × 10?14m23 and cT2 from 4 × 10?3 to 7 × 10?2°K2m?23. These results indicate greater turbulent activity at the higher latitudes. In the region near 45 km the refractive index fluctuations and the corresponding temperature fluctuations are substantially lower. Based on the analysis of one representative occultation measurement, cn2 = 2 × 10?16m?23and cT2 = 7.3 × 10?4°K2m?23 in the 45-km region. The fluctuations in this region also appear to be consistent with wind-shear-generated turbulence. The turbulence level is considerably weaker than that at 60 km; the energy dissipation rate ε is 4.9 × 10?5m2sec?3 and the small-scale eddy diffusion coefficient K is 2 × 103 cm2 sec?1.  相似文献   

9.
Based on a one-dimensional hydrodynamic model, we investigate carbon burning in a thermonuclear type-Ia supernova in the approximation of unsteady convection. The relatively broad range of convective parameters, 1×10?3≤αc≤2×10?3, in which delayed detonation from the edge takes place was found to be preserved only for cases with a low boundary temperature at the presupernova stage, T b (PS) = 6.4 × 106 K, and with a high envelope mass, mex ? 2 × 10?3M. In cases with a more realistic temperature, T b (PS) = 2 × 108 K, which corresponds to helium burning in the shell source, and with a lower mass mex, delayed detonation from the edge takes place only at αc = 2 × 10?3, while at αc = 1 × 10?3, numerous model pulsations occur during t?500 s. Artificial viscosity is shown to give a determining contribution to the increase in entropy in outer model shells, which is caused by the generation of weak shock waves during pulsations. We also show that the entropies calculated by two independent methods are equal.  相似文献   

10.
The impact light flash produced by electrostatically accelerated iron particles with diameters meters ranging from 5 to 0.05 μm and velocities lying between 1 km/sec and 30 km/sec has been investigated by means of photomultipliers. As target materials mainly gold and tungsten were used. The pulse of the multiplier was registered directly and after electronic integration. The pulse height of the multiplier signal, the amplitude of the integrated signal as well as its rise time were found to be unique functions of the mass and velocity of the impacting particle. For the pulse height of the differential signal the relation I = c1 × m1.25 × v5 was obtained, and for the integrated signal the relation I = c2 × m1.25 × v3.8, with only c1 and C2 depending on the target material. The rise time of the integrated signal follows the relation T = 2.2 × 102 × v?0.4 using gold as target, and in the case of tungsten material follows the relation T = 9.8 × 102 × v?1.2, where v is expressed in km/sec and T in μsec. Using the spectral distribution of the light intensity, measured by means of calibrated photomultipliers, the total amount of light energy emitted in the visible range could be calculated. As a result we obtained that for v = 4 km/sec and m = 10?11 g about 3 × 10?4 of the kinetic energy of the particle was converted into light energy. The variation of the impact flash intensity with the target material and the measured spectral distribution allowed the temperature of the crater after the impact to be estimated as between 2000 and 3000 K.  相似文献   

11.
J.E. Blamont  M. Festou 《Icarus》1974,23(4):538-544
Two monochromatic pictures of the Comet Kohoutek (1973f) were taken on January 15, 1974 in the resonance light (A2Σ ? X2 ∏) of the radical OH with a photographic telescope placed on board the NASA 990 Convair airplane. From an intensity profile we derive the production rate of OH radicals QOH = 4 xsx 1028 moleculesec ?1sr?1 at 0.6 AU and the lifetime of the OH radical which is τOH = 4.5 × 104 sec at 0.6 AU. This short lifetime (very similar to the lifetime of H2O) combined with the high total production rate of gas in comets can explain the observed velocity of 8km sec?1 for the H-atoms: The H-atoms produced by photodissociation of H2O are thermalized at short distancesfrom the nucleus; the H-atoms produced by photodissociation of OH have a velocity of ?8km sec?1 and can reach the outer part of the hydrogen envelope.  相似文献   

12.
This paper presents a new family of interior solutions of Einstein–Maxwell field equations in general relativity for a static spherically symmetric distribution of a charged perfect fluid with a particular form of charge distribution. This solution gives us wide range of parameter, K, for which the solution is well behaved hence, suitable for modeling of superdense star. For this solution the gravitational mass of a star is maximized with all degree of suitability by assuming the surface density equal to normal nuclear density, ρ nm=2.5×1017 kg?m?3. By this model we obtain the mass of the Crab pulsar, M Crab, 1.36M and radius 13.21 km, constraining the moment of inertia >?1.61×1038 kg?m2 for the conservative estimate of Crab nebula mass 2M . And M Crab=1.96M with radius R Crab=14.38 km constraining the moment of inertia >?3.04×1038 kg?m2 for the newest estimate of Crab nebula mass, 4.6M . These results are quite well in agreement with the possible values of mass and radius of Crab pulsar. Besides this, our model yields moments of inertia for PSR J0737-3039A and PSR J0737-3039B, I A =1.4285×1038 kg?m2 and I B =1.3647×1038 kg?m2 respectively. It has been observed that under well behaved conditions this class of solutions gives us the overall maximum gravitational mass of super dense object, M G(max)=4.7487M with radius $R_{M_{\max}}=15.24~\mathrm{km}$ , surface redshift 0.9878, charge 7.47×1020 C, and central density 4.31ρ nm.  相似文献   

13.
The model of a presupernova’s carbon-oxygen (C-O) core with an initial mass of 1.33 M , an initial carbon abundance X C (0) =0.27, and a mean rate of increase in mass of 5 × 10?7 M yr?1 through accretion in a binary system evolved from the central density and temperature ρc=109 g cm?3 and T c=2.05 × 108K, respectively, by forming a convective core and its subsequent expansion to an explosive fuel ignition at the center. The evolution and explosion equations included only the carbon burning reaction 12C+12C with energy release corresponding to the complete conversion of carbon and oxygen (at the same rate as that of carbon) into 56Ni. The ratio of mixing length to convection-zone size αc was chosen as the parameter. Although the model assumptions were crude, we obtained an acceptable (for the theory of supernovae) pattern of explosion with a strong dependence of its duration on αc. In our calculations with sufficiently large values of this parameter, αc=4.0 × 10?3 and 3.0×10?3, fuel burned in the regime of prompt detonation. In the range 2.0×10?3≥αc≥3.0×10?4, there was initially a deflagration with the generation of model pulsations whose amplitude gradually increased. Eventually, the detonation regime of burning arose, which was triggered from the model surface layers (with m ? 1.33 M ) and propagated deep into the model up to the deflagration front. The generation of model pulsations and the formation of a detonation front are described in detail for αc=1.0 × 10?3.  相似文献   

14.
In this paper, we modify our previous research carefully, and derive a new expression of electron energy density in superhigh magnetic fields. Based on our improved model, we re-compute the electron capture rates and the magnetic fields’ evolutionary timescales t of magnetars. According to the calculated results, the superhigh magnetic fields may evolve on timescales ~(106?107) yrs for common magnetars, and the maximum timescale of the field decay, t≈2.9507×106 yrs, corresponding to an initial internal magnetic field B 0=3.0×1015 G and an initial inner temperature T 0=2.6×108 K. Motivated by the results of the neutron star-supernova remnant (SNR) association of Zhang and Xie (2011), we calculate the maximum B 0 of magnetar progenitors, B max~(2.0×1014?2.93×1015) G when T 0=2.6×108 K. When T 0~2.75×108?1.75×108 K, the maximum B 0 will also be in the range of ~1014?1015 G, not exceeding the upper limit of magnetic field of a magnetar under our magnetar model. We also investigate the relationship between the spin-down ages of magnetars and the ages of their SNRs, and explain why all AXPs associated with SNRs look older than their real ages, whereas all SGRs associated with SNRs appear younger than they are.  相似文献   

15.
This paper discusses SPA's measured at long VLF propagation paths in the lower ionosphere and their association with solar X-ray bursts observed by USNRL satellites in the 0–3 Å, 0–8 Å and 8–20 Å bands. Excellent correlations were found between the SPA importances (in degrees per Mm) and the logarithm of the X-ray burst peak intensities. A hardening of the X-ray burst spectra is evident for increasing importance of SPA's; the threshold energy required for the occurrence of such anomalies was estimated, it is 4.3×10?5 ergs cm?2 sec?1 in the main ionizing band of 0–3 Å. It was also possible to derive the effective recombination coefficient at the normal D-region height of 70 km, this beingα r≈6×10?6 cm3 sec?1; furthermore ion production rates were estimated during SPA's at heights below the reference level.  相似文献   

16.
Multiaperture K photometry and 2.0- to 2.5-μm spectrophotometry of Uranus and its ring system are presented. The photometric results are used, together with a previously published measurement, to set limits on the geometric albedos of Uranus and the rings at ~2.2 μm: (0.74 ± 0.02) × 10(su?4) ≤ pK (Uranus) ≤ (1.5 ± 0.3) × 10?4, and (2.7 ± 0.6) × 10?2pK (rings) ≤ (3.4 ± 0.1) × 10?2. Reflectance spectra of Uranus and Uranus plus rings show features in the planet's spectrum which are attributed to gaseous CH4 absorption, and a 2.20-μm feature in the combined spectrum which may be due to the rings. This feature is tentatively identified with either the 2.26-μm absorption feature of NH3 frost, or the 2.2-μm OH band exhibited by certain silicate minerals. The results of JHK photometry of Uranus' satellite, Ariel (U1), indicate that the infrared colors of this object are very similar to those of the satellites U2, U3, and U4.  相似文献   

17.
G.S. Orton  H.H. Aumann 《Icarus》1977,32(4):431-436
The Q and R branches of the C2H2 ν5 fundamental, observed in emission in an aircraft spectrum of Jupiter near 750 cm?1, have been analyzed with the help of an improved line listing for this band. The line parameters have been certified in the laboratory with the same interferometer used in the Jovian observations. The maximum mixing ratio of C2H2 is found to be between 5 × 10?8 and 6 × 10?9, depending on the form of its vertical distribution and the temperature structure assumed for the lower stratosphere. Most consistent with observations of both Q and R branches are: (1) distributions of C2H2 with a constant mixing ratio in the stratosphere and a cutoff at a total pressure of 100 mbar or less, and (2) the assumption of a temperature at 10?2 bar which is near 155°K.  相似文献   

18.
We present the results of measurements of the total X-ray flux from the Andromeda galaxy (M31) in the 3-100 keV band based on data from the RXTE/PCA, INTEGRAL/ISGRI, and SWIFT/BAT space experiments. We show that the total emission from the galaxy has a multicomponent spectrum whose main characteristics are specified by binaries emitting in the optically thick and optically thin regimes. The galaxy’s luminosity at energies 20–100 keV gives about 6% of its total luminosity in the 3–100 keV band. The emissivity of the stellar population in M31 is L 2–20 keV ~ 1.1 × 1029 erg s?1 M ?1 in the 2–20 keV band and L 20–100 keV ~ 8 × 1027 erg s?1 M ?1 in the 20–100 keV band. Since low-mass X-ray binaries at high luminosities pass into a soft state with a small fraction of hard X-ray emission, the detection of individual hard X-ray sources in M31 requires a sensitivity that is tens of times better (up to 10?13 erg s?1 cm?2) than is needed to detect the total hard X-ray emission from the entire galaxy. Allowance for the contribution from the hard spectral component of the galaxy changes the galaxy’s effective Compton temperature approximately by a factor of 2, from ~1.1 to ~2.1 keV.  相似文献   

19.
Shock wave and thermodynamic data for rock-forming and volatile-bearing minerals are used to determine minimum impact velocities (vcr) and minimum impact pressures (pcr) required to form a primary H2O atmosphere during planetary accretion from chondritelike planetesimals. The escape of initially released water from an accreting planet is controlled by the dehydration efficiency. Since different planetary surface porosities will result from formation of a regolith, vcr and pcr can vary from 1.5 to 5.8 km/sec and from 90 to 600 kbar, respectively, for target porosities between 0 and ~45%. On the basis of experimental data, hydration rates for forsterite and enstatite are derived. For a global regolith layer on the Earth's surface, the maximum hydration rate equals 6 × 1010 g H2O sec?1 during accretion of the Earth. Attenuation of impact-induced shock pressure is modeled to the extent that the amount of released water as a function of projectile radius, impact velocity, weight fraction of water in the target, target porosity, and dehydration efficiency can be estimated. The two primary processes considered are the impact release of water bound in hydrous minerals (e.g., serpentine) and the subsequent reincorporation of free water by hydration of forsterite and enstatite. These processes are described in terms of model calculations for the accretion of the Earth. Parameters which lead to a primary atmosphere/hydrosphere are: an accretion time of ? 1.6 × 108years, the use of an accretion model defined by Weidenschilling (1974, 1976), a mean planetesimal radius of 0.5 km, a hydration rate of 6 × 1010 g H2O sec?1 inferred from a mean porosity of ~ 10% for the upper 1 km of the accreting Earth, and values for the dehydration efficiency, DE, of 0.55 and 0.07 for the maximum and minimum pressure decay model, respectively. Conditions which prohibit the formation of a primary atmosphere include an accretion time much longer than 1.6 × 108 years, a hydration rate for forsterite and enstatite well in excess of 6 × 1010 g H2O sec?1, and a dehydration efficiency DE < 0.07. We conclude that the concept of dehydration efficiency is of dominant importance in determining the degree to which an accreting planet acquires an atmosphere during its formation.  相似文献   

20.
V.S. Safronov  E.L. Ruskol 《Icarus》1982,49(2):284-296
A two-stage growth of the giant planets, Jupiter and Saturn, is considered, which is different from the model of contraction of large gaseous protoplanets. In the first stage, within a time of ~3 × 107 years in Jupiter's zone and ~2 × 108 years in Saturn's zone, a nucleus forms from condensed (solid) material having the mass, ~1028 g, necessary for the beginning of acceleration. The second stage may gravitating body, and a relatively slow accretion begins until the mass of the planet reaches ~10 m. Then a rapid accretion begins with the critical radius less than the radius of the Hill lobe, so that the classical formulae for the rate of accretion may be applied. At a mass m > m1 ≈ 50 m accretion proceeds slower than it would according to these formulae. When the planet sweeps out all the gas from its nearest zone of feeding (m = m2 ≈ 130 m), the width of the exhausted zone being built13 of the whole zone of the planet) growth is provided the slow diffusion of gas from the rest of the zone (time scale increases to 105?106 years and more). The process is terminated by the dissipation of the remnants of gas. In Saturn's zone m1 > m2 ≈ 30 m. The initial mass of the gas in Jupiter's zone is estimated. Before the beginning of the rapid accretion about 90% of the gas should have been lost from the solar system, and in the planet's zone less than two Jupiter masses remain. The highest temperature of Jupiter's surface, ≈5000°K, is reached at the stage of rapid accretion, m < 100 m, when the luminosity of the planet reaches 3 × 10?3 L. This favors an effective heating of the inner parts of the accretionary disk and the dissipation of gas from the disk. The accretion of Saturn produced a temperature rise up to 2000?2400° K (at m ≈ 20?25 m) and a luminosity up to 10?4 L.  相似文献   

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