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1.
The excitation, energy transfer and quenching of O2 (A3 Σu+, C3 Δu, c1 Σu?) and O(1S) are discussed, taking into account laboratory measurements and observations on the airglow of the Earth, Venus and Mars. The excitation of O(1S) occurs by the Barth mechanism with O2(c) as a precursor: the rate coefficient is 2.5 × 10?12 cm3 s?1 for υ > 0 and 2.5 × 10?12 exp(?1100T) cm3 s?1for υ = 0. The O2(c) can be formed directly by recombination or by O2(A) and O2(C) colliding with other molecules; the O2(c) yield through quenching of these states is about 0.3 in air and about 1.0 in carbon dioxide. The rate coefficients of some processes that control the molecular oxygen bands and the atomic oxygen green line are estimated.  相似文献   

2.
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   

3.
We studied the intermediate polar TVCol during and after its flare in November 1982 observed in the ultraviolet range with the International Ultraviolet Explorer. Two spectra revealing the variations of emission lines at different times are presented. We have estimated a new value of the reddening from the 2200 Å absorption feature, E (B ? V ) = 0.12 ± 0.02, and calculated the line fluxes of C IV and He II emission lines produced in the outer accretion disk. The average ultraviolet luminosity of emitting region during and after the flare is approximately 4 × 1032 erg s?1 and 9 × 1030 erg s?1, the corresponding average mass accretion rate is nearly 3 × 1015 erg s?1 (4.76 × 10?11M⊙ yr?1) and 5 × 1013 erg s?1 (7.93 × 10?13M⊙ yr?1), and the average temperature of the emitting region during and after flare is estimated to be of about 3.5 × 103 K and 2 × 103 K. We attribute this flare to a sudden increase in the mass accretion rate leading to the outburst activity.  相似文献   

4.
A radiative seasonal model which incorporates a multilayer radiative transfer treatment at wave-lengths longward of 7 μm is presented and applied to Saturn's stratosphere. Opacities due to H2-He, CH4, C2H2, and C2H6 are included. Season-dependent insolation is shown to produce a strong hemispheric asymmetry decreasing with depth at the Voyager encounter times, and seasonal amplitudes of 30°K at the poles are predicted in the high stratosphere. The ring-modulated dependence of the insolation and the orbital eccentricity are shown to have a significant effect. Calculations agree closely with the Voyager 1 and 2 radio occultation ingress profiles recorded at 76°S and 36.5°S for CH4/H2 = 3.5 + 1.4/? 1.0 × 10?3;the estimated errors include modeling systematic errors and uncertainties in the occultations profiles. The possible role of aerosols in the stratospheric heating is analyzed. The Voyager 2 egress profile recorded at 31°S cannot be reproduced by calculations. Some constraints on the C2H2 and C2H6 abundances are derived. The upper portion of the occultation profiles (p < 3mbar) can be matched for C2H2/H2 = 1.0 + 1.3/?0.6 × 10?7, C2H6/H2 = 1.5 + 1.8/?0.9 × 10?6 at 76°S and C2H2/H2 = 4 + 6/?4 × 10?8, C2H6/H2 = 6 + 9/?6 × 10?7 at 36.5°N. At the northern occultation latitude, the discrepancy with the concentrations derived from analysis of IRIS spectra by R. Courtin, D. Gautier, A. Marten, B. Bézard, and R. Hanel (1984, Astrophys. J.287) can be explained by a sharp variation of the mixing ratios of these gases with altitude in the upper stratosphere. Other interpretations are discussed.  相似文献   

5.
The giant post-flare arch of 6 November 1980 revived 11 hr and 25 hr after its formation. Both these revivals were caused by two-ribbon flares with growing systems of loops. The first two brightenings of the arch were homologous events with brightness maxima moving upwards through the corona with rather constant speed; during all three brightenings the arch showed a velocity pattern with two components: a slow one (8–12 km?1), related to the moving maxima of brightness, and a fast one (～ 35 km s?1), the source of which is unknown. During the first revival, at an altitude of 100000 km, temperature in the arch peaked ～ 1 hr, brightness ～ 2 hr, and emission measure ～ 3.5 hr after the onset of the brightening. Thus the arch looks like a magnified flare, with the scales both in size and time increased by an order of magnitude. At ～ 100000 km altitude the maximum temperature was ?14 × 106K, max.n e? 2.5 × 109cm?3, and max. energy density ? 11.2 erg cm?3. The volume of the whole arch can be estimated to 1.1 × 1030 cm3, total energy ?1.2 × 1031 erg, and total mass ?4.4 × 1015g. The density decreased with the increasing altitude and remained below 7 × 109 cm?3 anywhere in the arch. The arch cooled very slowly through radiation whereas conductive cooling was inhibited. Since its onset the revived arch was subject to energy input within the whole extent of the preexisting arch while a thermal disturbance (a new arch?) propagated slowly from below. We suggest that the first heating of the revived arch was due to reconnection of some of the distended flare loops with the magnetic field of the old preexisting arch. The formation of the ‘post’-flare loop system was delayed and started only some 30–40 min later. Since that time a new arch began to be formed above the loops and the velocities we found reflect this formation.  相似文献   

6.
We report on simultaneous optical and infrared observations of the Halley Family comet 8P/Tuttle performed with the ESO Very Large Telescope. Such multi-wavelength and coordinated observations are a good example of what can be done to support space missions. From high resolution optical spectroscopy of the CN (0,0) 388 nm and NH2 (0,9,0) 610 nm bands using UVES at UT2 we determined 12C/13C = 90 ± 10 and 14N/15N = 150 ± 20 in CN and we derived a nuclear spin temperature of NH3 of 29 ± 1 K. These values are similar to those found in Oort-Cloud and Jupiter Family comets. From low resolution long slit spectroscopy with FORS1 at UT2 we determined the CN, C3 and C2 production rates and the parent and daughter scale lengths up to 5.2 105 km tailward. From high resolution IR spectroscopy with CRIRES at UT1 we measured simultaneously the production rates and mixing ratios of H2O, HCN, C2H2, CH4, C2H6, and CH3OH.  相似文献   

7.
Spectroscopic observations of Comet P/Brorsen-Metcalf were made on August 9–13, 1989. Spatial profiles extracted from long-slit spectra were analyzed to determine the lifetimes of C3 and NH2 radicals and their parents, as well as the tailward acceleration of these radicals. In our investigations we used a Monte Carlo model. The average lifetime for C3 has been found to be 6.3 × 104 s and that for the parent of C3 to 6 × 103 s. The spatial profiles of C3 were almost symmetric and we need only 0.1 cm s−2 as the tailward acceleration. According to our simulations, C3H4 (allene) can be considered as the parent for C3. We obtained the average value 7.6 × 104 s for the lifetime of NH2 and 1.1 × 104 s for the lifetime of the NH2 parent. The tailward acceleration of NH2 was not more than 0.1 cm s−2. This result does not exceed the latest theoretical calculations of NH2 and NH3 lifetimes by a factor of 1.4. So, NH3 may be considered as a parent for NH2 in the atmosphere of P/Brorsen-Metcalf.  相似文献   

8.
A review is given of the stratospheric budgets of odd oxygen, odd nitrogen, nitrous oxide, methane and carbonyl sulfide. The stratospheric column production rate of NO by the reaction N2O + O(1D) → 2 NO is 1.1–1.9 × 108 molecules cm?2 s?1. The stratospheric loss rates for N2O, CH4 and COS are equal to 0.9–1.4 × 109, 1 × 1010 and 0.5 × 107 molecules cm?2 s?1, respectively. From currently available information on the global distributions of N2O and CH4 there are some indications of about two times smaller OH concentrations below 35 km than those which are calculated based on the latest compilation of kinetic data.Most significantly, however, it is shown that photochemical models and available ozone observations cannot be reconciled and that there may be particularly severe problems in the 25–35 km region. This issue is thoroughly discussed.Volcanic emissions of SO2 to the stratosphere may locally lead to much enhanced ozone concentrations and heating rates. These may influence the dynamic behaviour of volcanic plumes before their dispersion over large volumes of the stratosphere.  相似文献   

9.
We reduced ultraviolet spectra of Saturn from the IUE satellite to produce a geometric albedo of the planet from 1500 to 3000 Å. By matching computer models to the albedo we determined a chemical composition consistent with the data. This model includes C2H2 and C2H6 with mixing ratios and distributions of (9 ± 3) × 10?8 in the top 20 mbar of the atmosphere with none below for C2H2 and (6 ± 1) × 10?6 also in the top 20 mbar with none below for C2H6. The C2H2 and C2H6 distributions and the C2H6 mixing ratio are taken directly from the Voyager IRIS model [R. Courtin et al., Bull. Amer. Astron. Soc.13, 722 (1981), and private communication]. The Voyager IRIS model also includes PH3, which is not consistent with the uv albedo from 1800 to 2400 Å. Our model requires a previously unidentified absorber to explain the albedo near 1600 Å. After considering several candidates, we find that the best fit to the data is obtained with H2O, having a column density of (6 ± 1) × 10?3 cm-am.  相似文献   

10.
RX J1856.5–3754 is one of the brightest nearby isolated neutron stars, and considerable observational resources have been devoted to it. However, current models are unable to satisfactorily explain the data. We show that our latest models of a thin, magnetic, partially ionized hydrogen atmosphere on top of a condensed surface can fit the entire spectrum, from X-rays to optical, of RX J1856.5–3754, within the uncertainties. In our simplest model, the best-fit parameters are an interstellar column density N H≈1×1020 cm?2 and an emitting area with R ∞≈17 km (assuming a distance to RX J1856.5–3754 of 140 pc), temperature T ∞≈4.3×105 K, gravitational redshift z g ～0.22, atmospheric hydrogen column y H≈1 g cm?2, and magnetic field B≈(3–4)×1012 G; the values for the temperature and magnetic field indicate an effective average over the surface.  相似文献   

11.
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   

12.
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   

13.
Results of analysis of about 150 autocorrelation functions are presented for the period from about 2300 hr on 5 October to about 1200 hr on 7 October 1967. A large percentage concentration of helium ions are observed. It reaches a value as high as 50 per cent with a maximum at around 800 km. Downward heat fluxes deduced from the temperature variations yield a value of about 2–2.5 × 109 eV cm?2 sec?1 during the period 1200–1600 hr and a value of about 1.5 × 108 eV cm?2 sec?1 during the period 0100–0400 hr at night. These agree well with other measurements. The O+ ions are found not to be in diffusive equilibrium, and from the O+ fluxes and the electron density profiles, the O+ drift velocity has been estimated. It is found that the speed can be as high as 1–5 × 103 cm sec?1 even at altitudes as high as 700 km.  相似文献   

14.
In an updating of energy characteristics of lightnings on Venus obtained from Venera-9 and -10 optical observations, the flash energy is given as 8 × 108 J and the mean energy release of lightnings is 1 erg cm?2 s which is 25 times as high as that on the Earth. Lightnings were observed in the cloud layer. The stroke rate in the near-surface atmosphere is less than 5 s?1 over the entire planet if the light energy of the stroke exceeds 4 × 105 J and less than 15 s?1 for (1–4) × 105 J.The average NO production due to lightnings equals 5 × 108 cm?2 s?1, the atomic nitrogen production is equal to 7 × 109 cm?2s?1,the N flux toward the nightside is 3.2 × 109 cm?2s?1, the number densities [N] = 3 × 107cm?3 and [NO] = 1.8 × 106cm?3 at 135 km. Almost all NO molecules in the upper atmosphere vanish interacting with N and the resulting NO flux at 90-80 km equals 5 × 105cm?2s?1, which is negligibly small as compared with lightning production. If the predissociation at 80–90 km is regarded as the single sink of NO, its mixing ratio, fNO, is 4 × 10?8, for the case of a surface sink fNO = 0.8 × 10?9 at 50 km. Excess amounts, fNO ? 4 × 10?8, may exist in the thunderstorm region.  相似文献   

15.
Having analyzed the 1999 scanning observations of the Galactic-center region with the PCA spectrometer onboard the RXTE observatory, we obtained upper limits on the flux from the microlensing black hole OGLE-1999-BUL-32 in 1999–2000. We show that the X-ray luminosity of this black hole did not exceed L x ? 3 × 1033(d/1kpc)2 erg s?1. Near the maximum amplification of the background star (on June 6, 1999), the upper limit was L x ? 7 × 1033(d/1kpc)2 erg s?1.  相似文献   

16.
The Devasthal Fast Optical Telescope (DFOT) is a 1.3 meter aperture optical telescope, recently installed at Devasthal, Nainital. We present here the first results using an Hα filter with this telescope on a Wolf–Rayet dwarf galaxy Mrk 996. The instrumental response and the Hα sensitivity obtained with the telescope are (3.3 ± 0.3) × 10???15 erg s?1 cm?2/counts s?1 and 7.5 × 10???17 erg s?1 cm?2 arcsec?2 respectively. The Hα flux and the equivalent width for Mrk 996 are estimated as (132 ± 37) × 10?14 erg s?1 cm?2 and ～96 Å respectively. The star formation rate is estimated as 0.4 ± 0.1M ⊙ yr?1. Mrk 996 deviates from the radio-FIR correlation known for normal star forming galaxies with a deficiency in its radio continuum. The ionized gas as traced by Hα emission is found in a disk shape which is misaligned with respect to the old stellar disk. This misalignment is indicative of a recent tidal interaction in the galaxy. We believe that galaxy–galaxy tidal interaction is the main cause of the WR phase in Mrk 996.  相似文献   

17.
Microrater frequencies caused by fast (? 3 km s?1) ejecta have been determined using secondary targets in impact experiments. A primary projectile (steel sphere, diam 1.58 mm, mass 1.64 × 10?2 g) was shot in Duran glass with a velocity of 4.1 km s?1 by means of a light gas gun. The angular distribution of the secondary crater number densities shows a primary maximum around 25°, and a secondary maximum at about 60° from the primary target surface. The fraction of mass ejected at velocities of ? 3 km s?1 is only a factor of 7.5 × 10?5 of the primary projectile mass. A conservative calculation shows that the contribution of secondary microcraters (caused by fast ejecta) to primary microcrater densities on lunar rock surfaces (caused by interplanetary particles) is on the statistical average below 1% for any lunar surface orientation. Calculation of the interplanetary dust flux enhancement caused by Moon ejecta turned out to be in good agreement with Lunar Explorer 35in situ measurements.  相似文献   

18.
R. P. Kane 《Solar physics》2014,289(7):2669-2675
When a Coronal Mass Ejection (CME) is ejected by the Sun, it reaches the Earth orbit in a modified state and is called an ICME (Interplanetary CME). When an ICME blob engulfs the Earth, short-scale cosmic-ray (CR) storms (Forbush decreases, FDs) occur, sometimes accompanied by geomagnetic Dst storms, if the B z component in the blob is negative. Generally, this is a sudden process that causes abrupt changes. However, sometimes before this abrupt change (FD) due to strong ICME blobs, there are slow, small changes in interplanetary parameters such as steady increases in solar wind speed V, which are small, but can last for several hours. In the present communication, CR changes in such an event are illustrated in the period 1?–?3 October 2013, when V increased steadily from ～?200 km?s?1 to ～?400 km?s?1 during 24 hours on 1 October 2013. The CR intensities decreased by 1?–?2 % during some hours of this 24-hour interval, indicating that CR intensities do respond to these weak but long-lasting increases in interplanetary solar wind speed.  相似文献   

19.
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   

20.
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   

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