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31.
S. A. Lamzin 《Astrophysics and Space Science》1995,224(1-2):211-214
I argue that temperatures of spots, responsible for observed periodical light variations of T Tauri stars (TTS), are not known with reliable accuracy to discriminate between chromospheric and accretion theories of TTS 's phenomenon. The hypothesis is set up that spots on classical TTS (CTTS) are due to heating of stellar surface by radiation from a collisional accretion shock, whereas spots on weak line TTS (WTTS), at least in some cases, are connected with a collisionless accretion shock rather than chromospheric activity. Possible scenarios of WTTS interaction with circumstellar matter are discussed. 相似文献
32.
Two spectrophotometric scans of comet Levy (1990c) have been analysed to estimate Haser model column densities and production rates of CN andC
2 molecules. 相似文献
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The dynamics of the vortex lattice in the inner crust of a neutron star is considered. A general equation of motion is obtained
and solved under the assumption that there are regions of pinned and of free vortices. By comparing these solutions with observational
data for the Vela pulsar, the relative moments of inertia of regions of relaxation with the corresponding characteristic times
are calculated for two model stars with different equations of state. It is shown that the theory can be reconciled with observations
of the relaxation of pulsar angular velocity only for model stars with extremely stiff equations of state.
Translated from Astrofizika, Vol. 40, No. 1, pp. 67–76, January–March, 1997. 相似文献
37.
S. K. El-Labany 《Astrophysics and Space Science》1992,191(2):185-194
The propagation of an ion-acoustic soliton in a collisionless plasma with adiabatic positive and negative ions (with equal ion temperature) and hot non-isothermal electrons is studied by use of the renormalization method introduced by Kodama and Taniuti in the reductive perturbation method. The basic set of fluid equations describing the system is reduced to a Korteweg-de Vries (K-dV)-type equation for the first-order perturbed potential and to a linear inhomogeneous differential equation to the second-order of the perturbed potential. A stationary solution of the coupled equations is obtained. 相似文献
38.
Donald D. BOGARD Daniel H. GARRISON Jozef MASARIK 《Meteoritics & planetary science》2001,36(1):107-122
Abstract— The Monahans H‐chondrite is a regolith breccia containing light and dark phases and the first reported presence of small grains of halite. We made detailed noble gas analyses of each of these phases. The 39Ar‐40Ar age of Monahans light is 4.533 ± 0.006 Ma. Monahans dark and halite samples show greater amounts of diffusive loss of 40Ar and the maximum ages are 4.50 and 4.33 Ga, respectively. Monahans dark phase contains significant concentrations of He, Ne and Ar implanted by the solar wind when this material was extant in a parent body regolith. Monahans light contains no solar gases. From the cosmogenic 3He, 21Ne, and 38Ar in Monahans light we calculate a probable cosmic‐ray, space exposure age of 6.0 ± 0.5 Ma. Monahans dark contains twice as much cosmogenic 21Ne and 38Ar as does the light and indicates early near‐surface exposure of 13–18 Ma in a H‐chondrite regolith. The existence of fragile halite grains in H‐chondrites suggests that this regolith irradiation occurred very early. Large concentrations of 36Ar in the halite were produced during regolith exposure by neutron capture on 35Cl, followed by decay to 36Ar. The thermal neutron fluence seen by the halite was (2–4) × 1014 n/cm2. The thermal neutron flux during regolith exposure was ~0.4‐0.7 n/cm2/s. The Monahans neutron fluence is more than an order of magnitude less than that acquired during space exposure of several large meteorites and of lunar soils, but the neutron flux is lower by a factor of ≤5. Comparison of the 36Arn/21Necos ratio in Monahans halite and silicate with the theoretically calculated ratio as a function of shielding depth in an H‐chondrite regolith suggests that irradiation of Monahans dark occurred under low shielding in a regolith that may have been relatively shallow. Late addition of halite to the regolith can be ruled out. However, irradiation of halite and silicate for different times at different depths in an extensive regolith cannot be excluded. 相似文献
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