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1.
The electron collision excitation rates recently calculated for transitions in Si xiii by Keenan et al. (1987) are used to derive the electron temperature sensitive ratio G(=(f + i)/r and the density sensitive ratio R(=f/i), where i, f, and r are the intercombination (1s 2 1 S – 1s2p 3 P 1, 2) forbidden (1s 2 1 S – 1s2s 3 S), and resonance (1s 2 1 S – 1s2p 1 P), transitions respectively. Also estimated are the values of R in the low-density limit (R 0) as a function of electron temperature. The theoretical G ratio at the temperature of maximum emissivity for Si xiii, G(T m) = 0.70, is in much better agreement with the observed G for the 1985, May 5 flare determined by McKenzie et al. (G = 0.60 ± 0.07) than is the earlier calculation of Pradhan, who derived G(T m) = 0.85. The error in the observed R 0 ratio is so large that both our result and Pradhan's fall within the acceptable limits of uncertainty and hence one cannot estimate which of the two is the more accurate.  相似文献   

2.
Einstein's field theory of elementary particles (Einstein 1919) yields black holes with a mass M ˜ G−1 Λ−1/2c2 and a charge Q ˜ G−1/2λ−1/2c2, their curvatu re radius is Λ−1/2. Here 4Λ is an integration constant of Einstein's ‘trace-less’ gravitation equations. The choice λ = G−1h−1c3 for this constant defines Planckions and implies “strong gravity”. The choice λ = λ = 3Hinf2c−2 (where Hinf means the Hubble parameter of a final de Sitter cosmos) involves “weak gravity” and describes an electro-vac spherical universe.  相似文献   

3.
This paper considers the classical method to determine the electron temperatures t 3,O, t 2,O and t 2,N from forbidden lines of the ions O++, O+, and N+, and investigates the influence of uncertainties in atomic data on the accuracy of the determined electron temperatures. The uncertainties in atomic data (the Einstein coefficients for spontaneous transitions and electron ionization cross-sections) are estimated as discrepancies between the values computed by various authors. The error in the electron temperature caused by uncertainties in the atomic data is found to increase with the growth in the electron temperature. At a temperature 10000 K, the errors in the electron temperatures t 3,O, t 2,N, and t 2,O do not exceed 1, 3, and 7%, respectively.  相似文献   

4.
R-matrix calculations of the 11S - 23S and 11S - 23P electron excitation rates in He - like Cv, Ovii, and Mgxi by Kingston and Tayal are used to interpolate results for Neix. Adoption of these in emission line strength calculations leads to values for the density-sensitiveR ratio very similar to those of Pradhanet al. and Wolfsonet al., although the temperature-sensitiveG ratios are approximately 10 to 20 % lower than those deduced by these authors. However the present theoretical value ofG at the temperature of maximum Neix emission,G(T m) = 0.82, is in excellent agreement with those observed by the SMM and P78-1 satellites for the 1980, November5 flare (G = 0.83 ± 0.01) and nonflaring active regions (G = 0.80 ± 0.05), respectively.  相似文献   

5.
Rotational excitation cross sections and rate coefficients of AlF collisions with para-H2 are computed at low temperature, i.e., for T≤70 K. Prior to collisional calculations, a four-dimensional (4D) potential energy surface (PES) for the AlF-H2 system is calculated at the ab initio Coupled-Cluster level of the theory with an aug-cc-pVQZ Gaussian basis set. This 4D-PES is further reduced to a two-dimensional (2D) PES based on the considerations related to collisional studies with para-H2. The [Al-F] and [H-H] bond lengths are frozen at their experimental equilibrium value r e =1.654369 bohr and r e =1.4011 bohr respectively. The interaction energy presents a global minimum located ∼63 cm−1 below the AlF-H2 dissociation limit. With this PES, cross sections are determined in the Close-Coupling (CC) approach and rate coefficients are inferred by averaging the cross sections over a Maxwell-Boltzman distribution of kinetic energies. These quantities are significantly magnified in comparison with their AlF-He counterparts. The already observed propensity towards ΔJ=1 transitions for AlF-He remains.  相似文献   

6.
The gravitational instability of a nonrotating isothermal gaseous disk permeated by a uniform frozen-in magnetic field is investigated using a fourth-order perturbation technique. From the results it is found that the disk is stable whenn/B 0 < (4/33 G)–1/2, wheren andB are the column density of the disk and unperturbed magnetic field, respectively, andG is the gravitational constant. The disk is gravitationally unstable only whenn/B 0 > (4/33 G)–1/2.  相似文献   

7.
The phenomenological nature of a new gravitational type interaction between two different bodies derived from Verlinde’s entropic approach to gravitation in combination with Sorkin’s definition of Universe’s quantum information content, is investigated. Assuming that the energy stored in this entropic gravitational field is dissipated under the form of gravitational waves and that the Heisenberg principle holds for this system, one calculates a possible value for an absolute minimum time scale in nature t = \frac1516 \fracL1/2(h/2p) Gc4 ~ 9.27×10-105\tau=\frac{15}{16} \frac{\Lambda^{1/2}\hbar G}{c^{4}}\sim9.27\times10^{-105} seconds, which is much smaller than the Planck time t P =(ħG/c 5)1/2∼5.38×10−44 seconds. This appears together with an absolute possible maximum value for Newtonian gravitational forces generated by matter Fg=\frac3230\fracc7L (h/2p) G2 ~ 3.84×10165F_{g}=\frac{32}{30}\frac{c^{7}}{\Lambda \hbar G^{2}}\sim 3.84\times 10^{165} Newtons, which is much higher than the gravitational field between two Planck masses separated by the Planck length F gP =c 4/G∼1.21×1044 Newtons.  相似文献   

8.
The parameter G, which is determined from the general number of sunspots groups N g according to the daily observations G=∑(1/N g )2, is offered. This parameter is calculated for the days when there is at least one sunspots group. It characterizes the minimum epoch solar activity. Parameter G mounts to the maximum during the epoch close to the minimal activity of sunspots. According to the data of the sequence of sunspots group in Greenwich–USAF/NOAA observatory format, observation data of Kislovodsk solar station and also daily Wolf number, the changes of parameter G during 100 years were reconstructed. It is demonstrated in the paper that parameter G’s amplitude in minimal solar activity n is linked with the sunspot cycle’s amplitude W n+1 or one and half cycles. The 24th activity cycle prediction is calculated, which makes W 24=135(±12).  相似文献   

9.
Svensson  L. Å.  Ekberg  J. O.  Edlén  B. 《Solar physics》1974,34(1):173-179
The levels of the configuration 3s 23 p 53d of Fe ix have been experimentally determined from their combinations with 3s3 p 63d 3 D in the region 300–400 Å. Wavelengths can now be accurately predicted for all transitions within 3s 23 p 53d, and eight of these can be identified with coronal lines from 2042 to 4585 Å. Also, identifications of solar lines from 171 to 245 Å with electric-dipole and magnetic-quadrupole transitions to the ground state, 3s 23p 6 1 S, are confirmed and extended. Solar identifications with corresponding transitions in Ni xi, both within 3s 23 p 53d and to the ground state, are proposed on the basis of a short extrapolation.  相似文献   

10.
Coral reefs are net sinks for C, principally as CaCO3 accretion. It is possible to predict quite accurately the rate of production, given adequate information about any particular reef environment. The best data set for an extensive region is that for the Great Barrier Reef (GBR). Careful analysis of this region and the incorporation of previously documented present day system calcification rates suggest net production (G) from G = 1 (kg CaCO3 m−2 yr−1) for fringing reefs, to G = 1.9 for planar (infiled platform) reefs, G = 3 for ribbon reefs and lagoonal reefs. The 20,055 km2 of reefs in the GBR are thus estimated to average G = 2.4, resulting in a total production of 50 million tonnes yr−1. In a 50–100 year Greenhouse scenario of rising sealevel, we predict that recolonisation of present day reef flats will be extensive and prolific. Production will increase substantially, and this could be by as much as 40% (ranging from 0% for deep shoals to 180% for fringing reefs) to give 70 million tonnes yr−1 if the rate of sealevel rise reaches or exceeds 6–8 mm yr−1We estimate 115,000 km2 of oceanic atolls worldwide. Drawing on points equivalence from the detailed analysis of the GBR, we estimate the atolls presently produce 160 million tonnes yr−1. We predict that a similar 40% increase could be possible in the next 100 years or so resulting in a production of 220 million tonnes.Accepting an existing estimate of 617,000 km2 for reefs worldwide, drawing from our projections from the GBR and the atolls, and making some assumptions about the remaining reef types (we suggest fringing reefs to dominate) we estimate global reef production at the present time to be 900 million tonnes yr−1. Within the next 100 years or so, we suggest this rate could almost double to 1800 million tonnes. In the long term (several centuries) we predict that the continuing trend of recolonisation, particularly of fringing and planar reefs could result in the production of > 3000 million tonnes yr−1 if rates of sealevel rise approaching or exceeding 6–8 mm yr−1 are achieved. Eventually (> 500 yr), reefs could actually “drown” due to inability to match the rate of sealevel increase if that rate significantly exceeds 6–8 mm yr−1.Thus, coral reefs at present act as a sink for 111 million tonnes C yr−1, the equivalent of 2% of present output of anthropogenic CO2. In the short term Greenhouse scenario (100 yr) we predict this could increase to the equivalent of 4% of the present CO2 output. In the much longer term (several centuries), if all trends continue, this could increase to the equivalent of as much as 9% of the present CO2 output.Unfortunately, we also predict that this considerable sink for C will be most likely of negative value in alleviating Greenhouse because of the immediate effect of CaCO3 precipitation is to raise the PCO2 of the surface oceans — ie, ot encourage CO2 efflux to the atmosphere. We do not attempt to quantify this effect.Other Greenhouse changes such as seawater temperature increase, changes in cloud cover, increased rainfall and runoff, increased storm activity, and changes in dissolved CO2 concentration and surface ocean circulation may complicate the reef response. However, we suggest that sealevel rise will be the dominant influence, at least during the next 100 years or so.  相似文献   

11.
The galactic and Extragalactic photodissociation regions are primarily heated by photoelectrons ejected from the surface of interstellar dust grains by Far-ultraviolet (FUV) photons. But there is no direct mechanism to measure the photoelectric heating efficiency. To understand the role of dust grains in processing the Interstellar Radiation Field (ISRF) and heating the gas, we compare the intensities I CII, I CO and I FIR for (2 P 3/2→2 P 1/2) & (J = 1→ 0) line emission of CII & CO at 158 μm & 2.6 mm and integrated far-infrared from number of photodissociation regions, HII regions, planetary nebulae, reflection nebulae and high latitude translucent clouds (HLCs). It is found that I CII is linearly correlated with I FIR. In the cold medium where cloud is exposed to weak radiations temperature is low and most of the cooling is due to [CII] emissions. As a result the ratio of I CII/I FIR provide indirect method to evaluate the photoelectric heating efficiency. For the neutral cold medium it is evaluated to be ∼0.028. The FUV radiation field G 0 are estimated through the model calculation of I CII and I CO for different galactic and photodissociation regions. The intensity of FIR radiation I FIR are well represented as 1.23×10−4 G 0(ergs cm−2 s−1 sr−1) almost same as estimated for HLCs by Ingalls et al (2002). Hydrogen density for each source has also been estimated.  相似文献   

12.
Improved values of the proton impact excitation cross sections at coronal energies for all the Fe+12 ground configuration (3s 23p 2) transitions are presented. These were obtained by direct computer integration of the Schroedinger equation (with the states expressed in intermediate coupling) resulting from the semi-classical Coulomb excitation theory formulation of the process. Comparison is made with previous results. The associated rate constants at coronal temperatures are given and compared with the corresponding electron impact excitation rate constants. Some cross-section values for the Fe+13 3s 23p 2 P 1/22 P 3/2 excitation are also presented.  相似文献   

13.
This work reports theoretical infrared and electronic absorption spectra of formaldehyde and its ions in gas phase and H2O ice at different levels of theory. The vibrational frequencies from this work at B3LYP/6-311++G** level are in agreement with the experimental determinations. The gas phase dipole moment of neutral formaldehyde 2.4 D is in excellent agreement with the experimental value of 2.33 D. An influence of ice on vibrational frequencies of neutral formaldehyde molecule was obtained using Self Consistence Isodensity Polarizable Continuum Model (SCI-PCM) with dielectric constant 78.5. Significant shift in vibrational frequencies for neutral formaldehyde molecule when studied in H2O ice and upon ionization is observed. All the vibrational modes in cation and anion of formaldehyde in gas phase are red shifted than the corresponding modes in neutral formaldehyde. Two vibrational modes are blue shifted and all other modes are red shifted for neutral formaldehyde in H2O ice. Time dependent density functional theory (TDDFT) is used to study electronic absorption spectrum of neutral formaldehyde and its charged states. It is found that like neutral formaldehyde, its cation and anion also display strong σ→σ ∗ electronic transitions in vacuum and far UV regions. This study should help in detecting formaldehyde molecule and its ions in gas phase and in H2O ice in different astronomical environment.  相似文献   

14.
We address gravitation and inertia in the framework of a general gauge principle (GGP) which accounts for the gravitation gauge group G R generated by a hidden local internal symmetry implemented on the flat space. Following the method of phenomenological Lagrangians, we connect the group G R to a non-linear realization of the Lie group of the distortion G D of the local internal properties of six-dimensional flat space, M 6, which is assumed as a toy model underlying four-dimensional Minkowski space. We study the geometrical structure of the space of parameters and derive the Maurer–Cartan’s structure equations. We treat distortion fields as Goldstone fields, to which the metric and connection are related, and we infer the group invariants and calculate the conserved currents. The agreement between the proposed gravitational theory and available observational verifications is satisfactory. Unlike the GR, this theory is free of fictitious forces, which prompts us to address separately the inertia from a novel view point. We construct a relativistic field theory of inertia, which treats inertia as a distortion of local internal properties of flat space M 2 conducted under the distortion inertial fields. We derive the relativistic law of inertia (RLI) and calculate the inertial force acting on the photon in a gravitating system. In spite of the totally different and independent physical sources of gravitation and inertia, the RLI furnishes a justification for the introduction of the Principle of Equivalence. Particular attention is given to the realization of the group G R by the hidden local internal symmetry of the abelian group U loc=U(1) Y ×diag[SU(2)], implemented on the space M 6. This group has two generators, the third component T 3 of isospin and the hypercharge Y, implying Q d =T 3+Y/2, where Q d is the distortion charge operator assigning the number −1 to particles, but +1 to anti-particles. This entails two neutral gauge bosons that coupled to T 3 and Y. We address the rearrangement of the vacuum state in gravity resulting from these ideas. The neutral complex Higgs scalar breaks the vacuum symmetry leaving the gravitation subgroup intact. The resulting massive distortion field component may cause an additional change of properties of the spacetime continuum at huge energies above the threshold value.  相似文献   

15.
In a closed expanding-contracting Universe, matter will be subject to an inward acceleration large enough to prevent perpetual expansion. A closed Universe must also perform a simple harmonic motion, which might consist either of one single cycle or of an infinite series of oscillations about a central point. It is the purpose of this study to find the rate ofa 0, the cosmic acceleration, from which the gravitational constantG can be determined. It will be shown from Ampère's equation and Planck's radiation law that it is possible to derivea 0=7.623×10–12 ms–2, a value which also conforms with the uncertainty principle. The relationship betweena 0 and electromagnetic radiation is based on the concept that charges (such as electrons) must emit radiation while accelerating. The rate ofa 0 yields a universal gravitational constant ofG=6.645×10–11 N m2 kg–2.  相似文献   

16.
New electron excitation rates for O vii calculated by Tayal and Kingston using the R-matrix method are used to determine theoretical emission line strengths. Values of the electron density sensitive ratio R (forbidden line to intercombination line) are found to be very similar to those deduced by other authors. However the temperature sensitive ratios G (intercombination plus forbidden lines to resonance line) are approximately 20% lower than the best previous estimates. The observed value of G for solar active regions (G = 1.0 ± 0.1) predicts an electron temperature in the range 1.1 × 106 K < T e < 1.8 × 106 K, which overlaps that of maximum O vii emissivity, T M = 1.8 × 106 K. In addition, the theoretical G versus T e curve is in excellent agreement with that observed for a Tokamak plasma.  相似文献   

17.
The goal of this study was to explore prebiotic chemistry in a range of plausible early Earth and Mars atmospheres. To achieve this laboratory continuous flow plasma irradiation experiments were performed on N2/H2/CO/CO2 gas mixtures chosen to represent mildly reducing early Earth and Mars atmospheres derived from a secondary volcanic outgassing of volatiles in chemical equilibrium with magmas near present day oxidation state. Under mildly reducing conditions (91.79% N2, 5.89% H2, 2.21% CO, and 0.11% CO2), simple nitriles are produced in the gas phase with yield (G in molecules per 100 eV), for the key prebiotic marker molecule HCN at G∼1×10−3 (0.1 nmol J−1). In this atmosphere localized HCN concentrations possibly could approach the 10−2 M needed for HCN oligomerization. Yields under mildly oxidizing conditions (45.5% N2, 0.1% H2, 27.2% CO, 27.2% CO2) are significantly less as expected, with HCN at G∼3×10−5 (). Yields in a Triton atmosphere which can be plausibly extrapolated to represent what might be produced in trace CH4 conditions (99.9% N2, 0.1% CH4) are significant with HCN at G∼1×10−2 (1 nmol J−1) and tholins produced. Recently higher methane abundance atmospheres have been examined for their greenhouse warming potential, and higher abundance hydrogen atmospheres have been proposed based on a low early Earth exosphere temperature. A reducing (64.04% N2, 28.8% H2, 3.60% CO2, and 3.56% CH4), representing a high CH4 and H2 abundance early Earth atmosphere had HCN yields of G∼5×10−3 (0.5 nmol J−1). Tholins generated in high methane hydrogen gas mixtures is much less than in a similar mixture without hydrogen. The same mixture with the oxidizing component CO2 removed (66.43% N2, 29.88% H2, 0% CO2, and 3.69% CH4) had HCN yields of G∼1×10−3 (0.1 nmol J−1) but more significant tholin yields.  相似文献   

18.
The paper deals with the excitation of the helium singlet level 21 P in the homogeneous and filamentary models of quiescent prominences with following parameters: the optical thickness at the limit of helium Lyman continuum 1c M = 0.1–100, T e = 7000 K, n e = 5 × 1010 cm–3. Assuming a model He atom with seven discrete levels (11 S, 23 S, 21 S, 23 P, 21 P, 33 D, 31 D) and the continuum the steady state equations for the levels 23 S, 21 P and the continuum have been solved together with the radiative transfer equations for the line 584 Å and the continuum 504 Å. The variations with depth of the functions n 2 3 S /n 1 1 S (1 c), n 2 1 P /n 1 1 S (1c ), and n + He n e /n 1 1 S(1c ) as well as the intensities of the triplet (D3, 10830 Å) and singlet (16678, 20581 Å) lines have been calculated. Comparison with observations leads to the following conclusions: (1) The line intensities calculated for filamentary models of prominences agree better with observations than those for homogeneous ones. (2) The helium level 21 P is excited by diffuse field 584 Å being formed by recombinations and spontaneous transitions 21 P – 11 S and escaping from the prominence into the space between the filaments and to the surface. (3) Underpopulation of the singlet level 21 P may be explained by combination of weak excitation mechanism (recombinations and formation of the diffuse field 584 Å) and strong deexcitation mechanism (spontaneous transitions into the level 11 S).  相似文献   

19.
Newtonian cosmology is developed with the assumption that the gravitational constantG diminishes with time. The functional form adopted forG(t), a modification of a suggestion of Dirac, isG=A(k+t) –1, wheret is the age of the Universe and a small constantk is inserted to avoid a singularity in the two-body problem. IfR is the scale factor, normalized to unity at an epoch time , the differential equation is then . Here 0 is the mean density at the epoch time. With the above form forG(t), the solution is reducible to quadratures.The scale factorR either increases indefinitely or has one and only one maximum. LetH 0 be the present value of Hubble's constant /R and 0c the minimum density for a maximum ofR, i.e., for closure of the Universe. The conditions for a maximum lead to a boundary curve of 0c versusH 0 and the numbers indicate strongly that thisG-variable Newtonian model corresponds to an open universe. An upward estimate of the age of the Universe from 1010 yr to five times such a value would still lead to the same conclusion.The present Newtonian cosmology appears to refute the statement, sometimes made, that the Dirac model forG necessarily leads to the conclusion that the age of the Universe is one-third the Hubble time. Appendix B treats this point, explaining that this incorrect conclusion arises from using all the assumptions in Dirac (1938). The present paper uses only Dirac's final result, viz,G(k+t)–1, superposing it on the differential equation .  相似文献   

20.
We present the results of an analysis of the winds of two WC10 central stars of planetary nebulae, CPD-56°8032 and He 2-113. These two stars have remarkably similar spectra, although the former exhibits somewhat broader emission line widths. High resolution spectra (up to R=50 000) were obtained in May 1993 for both objects at the 3.9 m AAT, using the UCL Echelle Spectrograph. The fluxes in individual Cii auto-ionising multiplet components, many of which were blended, were derived. Lines originating from auto-ionising resonance states situated in the C2+ continuum are very sensitive to the electron temperature, since the population of the these levels is close to LTE. The measured widths and profile shapes of these transitions are presented and are in excellent agreement with those predicted on the basis of their calculated auto-ionising lifetimes. The wind electron temperature is derived for both stars from the ratio of the fluxes in four such transitions (T e =18 500 K±1 500 K for CPD-56° 8032 andT e =13 600 K±800 K for He 2-113). Optical depth effects are investigated using normal recombination lines to obtain an independent wind electron temperature estimate in excellent agreement with the dielectronic line analysis.  相似文献   

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